Part I -Turbinal bones 1. Turbinal bones 2. Turbinals in amniotes

Olfactory and thermoregulatory capacities in small terrestrial mammals: a turbinal bone approach

Message in a bottle for passionate students

To all students who do not view themselves in a highly competitive system, be assured that if you are motivated you will always find your place in science.

After a technical degree in conservation biology, I was not up to the standard university level.

Despite some OK grades, I was ranked last of my first year of master. Therefore, I did not qualify for the 2nd year of the master's degree. At that time, it was a big deal but I found another master.

Despite the difficulty to find a PhD position in France, I was accepted in two positions, thanks to my motivation and hard work.

Finally, I still get some hope that one day, the French government will stop cutting research budgets and understand that education and research are key to get us out of the current health, environmental, and social crises.

Corrected version of the PhD manuscript from the 29/07/2021.

Illustration of the subterranean rodent Cryptomys mechowi created from turbinals and skull surfaces generated in the following studies, with the original draw of Martina Nacházelová and the background picture of Raymond Mendez. Illustration: Quentin Martinez.

environmental, l, and social crises.

Turbinal bones

Turbinals (= turbinates) are bony structures involved in olfaction, heat, and moisture conservation, as well as protection of the respiratory tract (e.g. [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF]. First works on turbinals probably refers to human medicine where turbinals were named conchae (e.g. [START_REF] Bourgery | Traité complet de l'anatomie de l'homme: comprenant la médecine opératoire, avec planches lithographiées d'après nature[END_REF]. During the last decades, turbinals were largely understudied in comparison to other parts of the skull [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]. Indeed, turbinals are thin perforated and scrolled bony or cartilaginous plates (Fig. 1). Therefore, they are fragile and difficult to extract from the skull.

Past anatomists spent a lot of time to access these structures using tedious protocols such as saw band, fancy transparency projector, cardboard models, and different types of casts [START_REF] Watson | XXV. Further notes on the skull, brain, and organs of special sense of Diademodon[END_REF][START_REF] Dawes | The course of the nasal airstreams[END_REF][START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Folkow | Anatomical and functional aspects of the nasal mucosal and ophthalmic retia of phocid seals[END_REF][START_REF] Morgan | Airflow, gas deposition, and lesion distribution in the nasal passages[END_REF]. In this context, we may recognize the astonishing works of Simon Paulli and Sir Victor Negus (Paulli 1900a, b, c, Negus 1958) that became landmarks for the field.

Invented in the 80's, high-resolution X-ray micro-computed tomography (micro computed tomography, micro-CT, µCT) was first extremely expensive and dedicated to exceptional projects. Then, the improvements and popularization of this tool resulted in a significant cost reduction. Micro-CT completely revolutionized the sensory ecology field and especially for turbinals. Moreover, in a context where biodiversity drastically decreased, museum specimens became rare and highly valuable material. Therefore, micro-CT that is non-destructive, enables acquiring data from rare specimens such as holotypes or specimens from extinct or endangered species. It is also possible to perform micro-CT on alive animals (anesthetized) and even during movements (cineradiography). One of the first work on turbinals that used micro-CT was probably [START_REF] Ruben | The metabolic status of some Late Cretaceous dinosaurs[END_REF] who investigated respiratory turbinals in birds, crocodilians, and theropods. Since, the number of publications related to turbinals has exponentially increased.

However, the nasal cavity (and therefore turbinals) is probably still the least studied region of the mammalian skull despite its large volume occupancy [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]. Van Valkenburg and her team widely developed quantitative analyses based on turbinal data, acquired by micro-CT (e.g. Van Valkenburg et al. 2004, 2011, 2014a, Green et al. 2012). One of the biggest challenges is now the required time to process the data and in particular the segmentation (= isolation of an area of interest). In mammals, segmentation ranges from half a day to several days to properly extract all turbinals from one side (e.g. left side in the following studies). This process is longer in the case of noisy micro-CT images, fossils (Fig. 2), or for the species with highly complex turbinals (e.g. amphibious species). In the next few years, deep learning technology may considerably reduce this segmentation time. To date, some freeware already does exceptional interpolation jobs in structures such as endocasts (e.g. Biomedisa, Losel et al. 2020), but will need some customized protocols for structures such as turbinals. The number of studies related to mammalian turbinals are high and keep growing.

However, studies remain rare in other tetrapods (e.g. birds or lizards) where most of their turbinals are cartilaginous and therefore not visible with micro-CT. Recent development of staining methods (e.g. iodine or acid) provide further avenues in this field by enabling the contrast enhancement of soft tissue and therefore make them visible in micro-CT [START_REF] Pauwels | An exploratory study of contrast agents for soft tissue visualization by means of high resolution X[END_REF][START_REF] Gignac | Diffusible metazoan soft tissues[END_REF]).

Turbinals in amniotes

Turbinals are present in most amniotes with the exception of turtles and some fully aquatic mammals [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF][START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF]). However, these structures largely differ between groups in their relative size, complexity, location, and epithelial cover [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF][START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF][START_REF] Owerkowicz | Respiratory turbinates and the evolution of endothermy in mammals and birds. Great transformations in vertebrate evolution[END_REF]. A common dichotomy is made between respiratory and olfactory turbinals (e.g. [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF]. The first involved heat and moisture conservation whereas the latter involved olfaction (Fig. 3). Turbinals are mostly cartilaginous in sauropsids (e.g. lizards and birds) whereas they are mostly ossified in synapsids (e.g. extant mammals, [START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF].

In lizards and snakes (= extant lepidosaurs) turbinals are generally represented by a simplified lamella mostly covered by sensory epithelium (= olfactory turbinal) and therefore involved in smell [START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF]. Again, some reductions are known in aquatic and arboreal forms (Parson 1971). Three turbinals are present in crocodilians that are mostly covered by sensory epithelium [START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF]. Apparently, turtles are the only amniote to lack turbinals even at a very early embryonic stage [START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF]. In general, turbinals are more developed in endotherms and therefore have a huge morphological disparity related to their phylogenetic relationships, skull morphology, and ecology [START_REF] Bang | The surface pattern of the nasal mucosa and its relation to mucous flow a study of chicken and herring gull nasal mucosae[END_REF], 1964[START_REF] Bang | Anatomical adaptations for olfaction in the snow petrel[END_REF][START_REF] Bang | Olfaction in Rallidae (Gruiformes), a morphological study of thirteen species[END_REF][START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF][START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF], Van Valkenburg et al. 2004, 2011, 2014a, Green et al. 2012, Ruf 2014, 2020, Martinez et al. 2018, 2020, in prep. b). Birds generally possess two respiratory and one olfactory turbinals. The olfactory turbinal that is located in the posterior part varies from highly complex in kiwi to highly reduced in pigeons [START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF].

In mammals, turbinals generally occupied a large portion of the nasal cavity [START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF][START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF], Van Valkenburg et al. 2004, 2011, 2014a, Martinez et al. in prep. b, c, Fig. 1, 2, 3). Mammalian turbinals are usually discriminated in two distinct functional parts: the anterior respiratory turbinals and the posterior olfactory turbinals (Fig. 3). However, some turbinals (e.g. ethmo-tubinal I (etI) or naso-turbinal (nt), Fig. 1) may have a dual function. The number of respiratory turbinals in terrestrial mammals varies from 1 in the naked mole rat (Heterocephalus glaber) to 3 or 4 in some other rodent species (Martinez et al. in prep. a,[START_REF] Hofer | The external anatomy of the oro-nasal region of primates[END_REF]Fig. 4). The number of olfactory turbinals in terrestrial mammals varies from 1 or 2 in humans to about thirty in some perissodactyls or anteaters (Paulli 1900b, Hautier et al. 2019, pers. obs.). Fully aquatic mammals may lack turbinals [START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF]), but further investigations on these organisms are still awaited. In addition to the relative number of turbinals, their relative size and complexity highly vary between mammalian species [START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF][START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF], Van Valkenburg et al. 2004, 2011, 2014a, Green et al. 2012, Ruf 2014, 2020, Martinez et al. 2018, 2020, in prep. a, b, c). As a result, and in the light of the lack of developmental studies, there are difficulties to determine clear homology hypotheses in the turbinal of extant amniotes. This work is even more complicated in fossils and to date the origin of turbinals is not fully elucidated [START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF].

Maxillo-turbinal (one of the respiratory turbinals) might be one of the only turbinals for which the homology hypothesis was clearly identified in the amniote clade [START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF].

In synapsids, bony scars are interpreted as potential respiratory turbinals in the upper Permian therapsid Glanosuchus (~ 260 Mya, [START_REF] Hillenius | The evolution of nasal turbinates and mammalian endothermy[END_REF][START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF]. Respiratory ridges are also found in subsequent mesozoic therocephalians and cynodonts (= theriodonts, Hillenius 1994).

Olfactory turbinal ridges are described in some cynodonts, Diademodon and Thrinaxodon [START_REF] Watson | XXV. Further notes on the skull, brain, and organs of special sense of Diademodon[END_REF][START_REF] Brink | Speculations on some advanced mammalian characteristics in the higher mammal-like reptiles[END_REF][START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF][START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF] whereas hadrosaur dinosaurs may have large olfactory turbinals [START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF]. Evidence of respiratory and olfactory turbinals in the nasal cavity of non-mammaliaform cynodonts suggested that in the upper Triassic, turbinals may have been already similar to those in extant mammals [START_REF] Ruf | Nasal anatomy of the non-mammaliaform cynodont Brasilitherium riograndensis (Eucynodontia, Therapsida) reveals new insight into mammalian evolution[END_REF].

Since turbinals are mostly cartilaginous in sauropsids, fossil evidence is still unclear and highly debated. Concerning respiratory turbinals, paleontologists extrapolate on the shape and the cross section of the nasal cavity of sauropsids [START_REF] Ruben | The metabolic status of some Late Cretaceous dinosaurs[END_REF][START_REF] Ruben | Selective factors associated with the origin of fur and feathers[END_REF]. For example, late cretaceous ornithurine Hesperornis (~ 80 Mya) presents a nasal cavity similar to the one of extant birds [START_REF] Witmer | The evolution of the antorbital cavity of archosaurs: a study in soft-tissue reconstruction in the fossil record with an analysis of the function of pneumaticity[END_REF]. Therefore, [START_REF] Hillenius | The evolution of endothermy in terrestrial vertebrates: Who? When? Why?[END_REF] hypothesized that this genus may have similar respiratory turbinals than extant birds. Based on the absence of respiratory turbinals in theropod dinosaurs (e.g. Archaeopteryx), [START_REF] Ruben | Selective factors associated with the origin of fur and feathers[END_REF] hypothesized that early birds may have been ectotherms. Also, some scars found in Tyrannosaurus (~ 75 Mya) may be interpreted as potential olfactory turbinals [START_REF] Ruben | The metabolic status of some Late Cretaceous dinosaurs[END_REF].

Synapsids and sauropsids probably diverged in the Carboniferous (~ 319 310 Mya, Reisz & Muller 2004[START_REF] Van Tuinen | Error in estimation of rate and time inferred from the early amniote fossil record and avian molecular clocks[END_REF] whereas recent studies suggested that mammals evolved from the late Triassic [START_REF] Bi | Three new Jurassic euharamiyidan species reinforce early divergence of mammals[END_REF]. Therefore, giving an age to the origins of turbinals is not possible and we do not know if it originates from a single event or from a convergence between synapsids and sauropsids [START_REF] Gauthier | Amniote phylogeny and the importance of fossils[END_REF]).

Turbinals in mammals

Among extant tetrapods, mammals have on average, the largest turbinals relative to their skull length (e.g. [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF], Parson 1971). Despite some studies in primates, Carnivora, bats, lagomorphs as well as rodents, the homology of turbinals remains unclear in several species of mammals with a lack of studies in some orders [START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF]. The difficulty of turbinal homology is mainly associated with olfactory turbinals (= fronto-and ethmo-turbinals, Fig. 1)

where increasing in turbinal complexity may increase the number of small and potentially independent lamellae. Even in rodents, the homology in olfactory turbinals is sometimes unclear, with some fronto-turbinal numbers ranging from 0 to 3 (Martinez et al. in prep. c,Fig. 4). In the light of variation in shape, location and number of these fronto-turbinals, some proper developmental studies must be done before providing some homological hypotheses that could be used into a phylogenetic framework. Similarly, it is difficult to distinguish between interturbinals and the potential lamellae of the olfactory-turbinals [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]. It is especially true for species with complex olfactory turbinal bones such as armadillos, elephants or tapirs (e.g. Paulli 1900b, Hautier et al. 2019, pers. obs.). In some cases, examinations of young individuals are enough because turbinals are often less complex in younger stages. However, in most cases precise developmental studies are necessary. To date, developmental studies remain rare and limited to some families (e.g. [START_REF] Ruf | Vergleichend-ontogenetische Untersuchungen an der Ethmoidalregion der Muroidea (Rodentia, Mammalia). Ein Beitrag zur Morphologie und Systematik der Nagetiere[END_REF], 2020[START_REF] Smith | Ontogeny and microanatomy of the nasal turbinals in lemuriformes[END_REF], 2020[START_REF] Smith | Nasal fossa of mouse and dwarf lemurs (Primates, Cheirogaleidae)[END_REF][START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF]. Therefore, more developmental studies will be necessary in the near future to further test hypotheses of turbinal homologies.

During the development of mammals, turbinals emerge from the nasal capsule [START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF][START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]. At early developmental stages, turbinals have three centers of chondrification: the pars anterior, the pars intermedia (= lateralis), and the pars posterior (Reinbach 1952b, Van Valkenburg et al. 2014[START_REF] Smith | Nasal fossa of mouse and dwarf lemurs (Primates, Cheirogaleidae)[END_REF], Maier and Ruf 2014, Ruf 2020). Anteriorly, turbinals are generally separated in the nasal cavity from left to right by the nasal septum. This structure that arises early in the ontogeny (from neural crest cells), remains mostly cartilaginous [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF], Ruf 2020). The posterior part, that will be ossified in adult stages is name mesethmoid [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]. Turbinals from the left and right side are symmetric and apart from some rare exceptions (Martinez et al. in prep. a, c), intra-individual variation (left to right) is rare [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF], Martinez et al. 2018, 2020, in prep. a, c).

Turbinal bones are generally discriminated in two categories, the (1) heat and moisture conservation on the one hand, and the (2) olfaction on the other hand (e.g. [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF][START_REF] Hillenius | The evolution of nasal turbinates and mammalian endothermy[END_REF]). These categories often fit with an antero-posterior discrimination with turbinals that are functionally named as respiratory and olfactory turbinals (Fig. 3). These bony structures exponentially increase the surface area of the nasal cavity covered by epithelium [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]. However, epithelial composition worn by turbinals varies between species.

Therefore, extensive histological studies in rats and mice (e.g. [START_REF] Gros | The projection of the olfactory epithelium on the olfactory bulb in the rabbit[END_REF][START_REF] Ressler | A zonal organization of odorant receptor gene expression in the olfactory epithelium[END_REF][START_REF] Harkema | Normal morphology of the nasal passages in laboratory rodents[END_REF][START_REF] Harkema | The nose revisited: a brief review of the comparative structure, function, and toxicologic pathology of the nasal epithelium[END_REF][START_REF] Barrios | Anatomy, histochemistry, and immunohistochemistry of the olfactory subsystems in mice[END_REF][START_REF] Herbert | Nose, larynx, and trachea[END_REF] and in some non-model species (e.g. [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Maier | Nasal structures in Old and New World primates[END_REF][START_REF] Smith | Distribution of olfactory epithelium in the primate nasal cavity: are microsmia and macrosmia valid morphological concepts?. The Anatomical Record Part A: Discoveries in Molecular[END_REF], 2012[START_REF] Smith | Nasal fossa of mouse and dwarf lemurs (Primates, Cheirogaleidae)[END_REF][START_REF] Eiting | The role of the olfactory recess in olfactory airflow[END_REF][START_REF] Yee | Comparative morphology and histology of the nasal fossa The[END_REF], Martinez et al. 2020) allow us to detail the distinct functions of turbinals.

In the two following parts, we will discuss anatomy of the turbinals from the anterior portion where the nares are located (= respiratory turbinals) to the posterior part that reaches the limit between the cribriform plate and the olfactory bulb (= olfactory turbinals, Fig. 3). In the respiratory turbinals we will discuss several structures that are named (1) margino-and atrio-, (2) maxillo-, and (3) naso-turbinals. In the olfactory turbinals we will discuss (1) lamina semicircularis, (2) fronto-, (3) ethmo-, and (4) inter-turbinals.

a. Respiratory turbinals

Respiratory turbinals are involved in heat and moisture conservation. During inhalation, the air is warmed up to body temperature with the contact of the vascularised anterior part of the respiratory turbinals. Simultaneously, the air in contact with nasal mucus is moistened. During subsequent exhalation, this warmed air is cooled down by the anterior portion of the respiratory turbinals that were previously cooled down by inspired air. This process condensates water from the nasal cavity and therefore conserves on average 66% of the humidity of the exhaled air (Fig. 6, [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Walker | Heat and water exchange in the respiratory tract[END_REF][START_REF] Jackson | Countercurrent heat exchange in the respiratory passages[END_REF][START_REF] Schmidt-Nielsen | Counter-current heat exchange in the respiratory passages: effect on water and heat balance[END_REF][START_REF] Collins | A model of respiratory heat transfer in a small mammal[END_REF][START_REF] Hillenius | The evolution of nasal turbinates and mammalian endothermy[END_REF][START_REF] Ruben | The metabolic status of some Late Cretaceous dinosaurs[END_REF][START_REF] Hillenius | The evolution of endothermy in terrestrial vertebrates: Who? When? Why?[END_REF]).

Respiratory turbinals are mostly covered to transitional and respiratory epithelium. By simplification, and in opposition to olfactory epithelium, several authors merged transitional and respiratory epithelium and only refer to the latter to describe the epithelium that lines respiratory turbinals. Respiratory epithelium is composed of six cell types: ciliated columnar, nonciliated columnar, mucous, brush, cuboidal, and basal cells. The variation in the composition of these cell types will change the properties of the respiratory epithelium in production of mucus, capacity to retain macro-and microscopic elements as well as enzyme activities [START_REF] Herbert | Nose, larynx, and trachea[END_REF]. The lamina propria (= most ventral part of the epithelium) of the respiratory epithelium is highly vascularized and contains many mucous glands. The transitional epithelium is a thin layer composed of cuboidal or low columnar cells that vary in their degree of ciliation.

Finally, respiratory turbinals are involved in the protection of the lower respiratory tract and of the posterior neuroepithelium. Indeed, respiratory turbinals filter, absorb, and dispose of both macro-and microscopic elements but also volatile elements causing injuries (e.g. [START_REF] Morgan | Airflow, gas deposition, and lesion distribution in the nasal passages[END_REF][START_REF] Harkema | The nose revisited: a brief review of the comparative structure, function, and toxicologic pathology of the nasal epithelium[END_REF]. These processes are performed thanks to the ciliated morphology of the respiratory epithelium but also by its absorption and regeneration properties.

We will discuss respiratory turbinals following: (1) margino-and atrio-, (2) maxillo-, and

(3) naso-turbinals.

i. Margino-and atrio-turbinals

In mammals the most anterior portion of the nasal cavity houses a cartilaginous structure named the outer nasal cartilage [START_REF] Maier | A neglected part of the mammalian skull: The outer nasal cartilages as progressive remnants of the chondrocranium[END_REF], Ruf 2020). This structure makes up the junction between the external nares and the nasal bones. Therefore, species with elongated rhinariums or trunks (e.g. shrews or macroscelides) bears a long outer nasal cartilage [START_REF] Maier | A neglected part of the mammalian skull: The outer nasal cartilages as progressive remnants of the chondrocranium[END_REF].

Anteriorly, the two first turbinals are fully cartilaginous at the adult stage and respectively named margino-and atrio-turbinals. In rodents, these turbinals are formed by the pars anterior (Ruf 2020). Due to their cartilaginous composition, these two turbinals are difficult to identify without precise histology. Therefore, in mammals, the mentions of margino-and atrio-turbinals are rare (e.g. [START_REF] De Beer | IX. The development of the skull of the shrew[END_REF], Reinbach 1952a, b, Maier 1980, 2000, 2020[START_REF] Ruf | Vergleichend-ontogenetische Untersuchungen an der Ethmoidalregion der Muroidea (Rodentia, Mammalia). Ein Beitrag zur Morphologie und Systematik der Nagetiere[END_REF], 2014, 2020[START_REF] Rossie | Ontogeny of the nasolacrimal duct in primates: functional and phylogenetic implications[END_REF][START_REF] Macrini | Comparative morphology of the internal nasal skeleton of adult marsupials based on x-ray computed tomography[END_REF], 2014, Maier & Ruf 2014), especially in group like rodents (e.g. [START_REF] Fawcett | The primordial cranium of microtus amphibius (water-rat), as determined by sections and a model of the 25mm stage. With comparative remarks[END_REF][START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF][START_REF] Ruf | Vergleichend-ontogenetische Untersuchungen an der Ethmoidalregion der Muroidea (Rodentia, Mammalia). Ein Beitrag zur Morphologie und Systematik der Nagetiere[END_REF], 2020). Because they are directly in contact with the exterior environment, margino-and atrio-turbinals are composed of lightly keratinized and squamous epithelium that may protect the posterior epithelium (Ruf 2014, 2020[START_REF] Herbert | Nose, larynx, and trachea[END_REF]. Margino-and atrio-turbinals are extremely complicated to discriminate and some authors refer to the first or the latter without clear homology, or even wrongly (see result section in Ruf 2020). Rare studies with very precise histology are able to differentiate between margino-, atrio-, and maxillo-turbinals by an incisura (e.g. Reinbach 1952a, b, in armadillo and Ruf 2004, 2020 in rodents). [START_REF] Maier | Ontogeny of the nasal capsule in cercopithecoids: a contribution to the comparative and evolutionary morphology of catarrhines[END_REF] identified a lack of atrio-turbinals in cercopithecoids and therefore a gap between margino-and maxillo-turbinals. In addition to their role in heat and moisture conservation, margino-and atrio-turbinals may also play a role in the shape of the nostril. Finally some link with facial muscles may imply a role in airflow direction into upper and lower components and even in the sniffing process [START_REF] Hofer | The external anatomy of the oro-nasal region of primates[END_REF], Gobbel 2000, Maier & Ruf 2014). Due to the difficulty to identify these two cartilaginous turbinals even with dice-ct scans, these turbinals remain widely understudied.

ii. Maxillo-turbinals Maxillo-turbinals start at the end of the atrio-turbinals when both atrio-and marginoturbinals are present [START_REF] Maier | Ontogeny of the nasal capsule in cercopithecoids: a contribution to the comparative and evolutionary morphology of catarrhines[END_REF], Ruf 2020). Maxillo-turbinals originate from the pars anterior and are generally fully ossified with the exception of the tip of the turbinal that remains cartilaginous in some species (Ruf 2020). Maxillo-turbinals are thought to be the largest respiratory turbinal, however there is a significant variation at the mammalian scale (Martinez et al. in prep. a,[START_REF] Hofer | The external anatomy of the oro-nasal region of primates[END_REF]c,Fig. 7).

iii. Naso-turbinals Naso-turbinals are located dorsally to the maxillo-turbinals and also originate from the pars anterior. In rodents, it is a distinct turbinal with no connection to other turbinals. In some mammals, the naso-turbinal is connected to the lamina semicircularis and therefore reaches the posterior part of the olfactory recess. In this case, some authors (mostly old literature) do not discriminate between the naso-turbinals and the lamina semicircularis (e.g. [START_REF] Gros | The projection of the olfactory epithelium on the olfactory bulb in the rabbit[END_REF] with the rabbit). The medio-posterior part of the naso-turbinal is often covered by olfactory epithelium, inducing a dual function in respiratory and olfactory processes. However, the epithelial cover of the naso-turbinals greatly varies between species [START_REF] Smith | Distribution of olfactory epithelium in the primate nasal cavity: are microsmia and macrosmia valid morphological concepts?. The Anatomical Record Part A: Discoveries in Molecular[END_REF], 2012[START_REF] Smith | Nasal fossa of mouse and dwarf lemurs (Primates, Cheirogaleidae)[END_REF][START_REF] Yee | Comparative morphology and histology of the nasal fossa The[END_REF][START_REF] Herbert | Nose, larynx, and trachea[END_REF].

Finally, naso-turbinals have a key function in directing the anterior airflow to the posterior olfactory recess and the olfactory turbinals. At least in placentals, the passage of the air through the naso-turbinal results in a decreasing airflow velocity in the olfactory recess that may increase absorption and therefore the correct detection of volatile odorant molecules (e.g. [START_REF] Craven | The fluid dynamics of canine olfaction: unique nasal airflow patterns as an explanation of macrosmia[END_REF]).

b. Olfactory turbinals

Olfactory turbinals are responsible for olfaction in supporting olfactory epithelium and neurons [START_REF] Ressler | A zonal organization of odorant receptor gene expression in the olfactory epithelium[END_REF][START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF][START_REF] Harkema | The nose revisited: a brief review of the comparative structure, function, and toxicologic pathology of the nasal epithelium[END_REF][START_REF] Barrios | Anatomy, histochemistry, and immunohistochemistry of the olfactory subsystems in mice[END_REF][START_REF] Herbert | Nose, larynx, and trachea[END_REF].

Olfactory turbinals chondrified and ossified antero-posteriorly and are generally fully ossified in adult stages ( Van Valkenburg et al. 2014[START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF]. It is well known that the relative size and complexity of olfactory turbinals significantly vary between species. Developmentally, extreme reduction is attributed to the merging of embryonic structures whereas extreme development may result from repetitive mesenchymal growth ( Van Valkenburg et al. 2014 b).

Olfactory turbinals are almost completely covered by olfactory epithelium. The olfactory epithelium is pseudostratified and composed of olfactory neurons, supporting cells, and basal cells [START_REF] Herbert | Nose, larynx, and trachea[END_REF]. At the dorsal surface of the olfactory epithelium, the olfactory vesicles of the olfactory neurons participate in increasing the surface area for the reception of odorant molecules. Olfactory neurons are ventrally extended by an axon that joins other axons and nerve fascicles. These nerve fascicles traverse the perforated cribriform plate to join glomeruli from the olfactory bulb (Fig. 5). The olfactory neurons are constantly regenerated with an estimated turnover rate of 30 days in the laboratory rat [START_REF] Graziadei | Continuous nerve cell renewal in the olfactory system[END_REF]. The lamina propria (= most ventral part of the epithelium) of the olfactory epithelium includes submucosal glands) which participates in moistening the olfactory epithelium and secrete a solvent between volatile odorant molecules and olfactory receptors. Some parts of the nasal roof, the nasal septum and the lateral wall of the olfactory recess, are also covered by olfactory epithelium [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF][START_REF] Herbert | Nose, larynx, and trachea[END_REF], Ruf 2020).

We will discuss olfactory turbinals following: (1) lamina semicircularis, (2) fronto-, (3) ethmo-, and (4) inter-turbinals (Fig. 1).

i. Lamina semicircularis

Because the lamina semicircularis is mostly covered by olfactory epithelium, it is often considered functionally as an olfactory turbinal (e.g. Martinez et al. 2018Martinez et al. , 2020)). However, it is not a turbinal but a part of the anterior paries nasi (pars anterior, Ruf 2014Ruf , 2020)). Here, we also consider the ventral projection named the uncinate process. The presence of this process and its size significantly varies between species without any particular phylogenetic or ecological pattern identified so far [START_REF] Macrini | Comparative morphology of the internal nasal skeleton of adult marsupials based on x-ray computed tomography[END_REF], 2014, Ruf 2014, 2020, Martinez et al. in prep. c).

ii. Fronto-turbinals

Fronto-turbinals are defined as turbinals located in the frontal recess and therefore do not meet the lamina transversalis [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF], Ruf 2020). The fronto-turbinals originate from the pars intermedia ( Van Valkenburg 2014[START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF] and are the first turbinals to ossify in Tupaia (Scandentia, Ruf 2020 citing [START_REF] Spatz | Beitrag zur Kenntnis der Ontogenese des Cranium von Tupaia glis[END_REF]. Fronto-turbinals can be attached to the lamina horizontalis (Ruf 2020) and are also described as turbinals that do not develop medially and remain far from the nasal septum [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]citing Allen 1882).

iii. Ethmo-turbinals Ethmo-turbinals originate from the pars posterior and therefore from the ethmoid bone ( Van Valkenburg 2014[START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF]. The ethmoid bone comprises several sub-structures: the ethmo-turbinals, the nasal septum, the cribriform plate, and the crista galli (Fig. 1, 3, Ruf 2020).

Ethmo-turbinals attached to the lamina horizontalis or on the sidewall of the olfactory recess (Ruf 2020). These turbinals are often connected posteriorly to the cribriform plate and therefore to the olfactory bulb via olfactory nerves (Fig. 5, [START_REF] Herbert | Nose, larynx, and trachea[END_REF], Ruf 2020). Ethmo-turbinals are generally more developed than fronto-turbinals and therefore considered as the structures that are most involved into olfactory processes.

Among ethmo-turbinals, the ethmo-turbinal I (etI) received much more attention than the others. Indeed, by its anterior projection and its division in two distinct pars (the pars anterior and posterior, Fig. 1), it is easy to identify the etI in divergent species [START_REF] Ruf | Ontogenetic transformations of the ethmoidal region in Muroidea (Rodentia, Mammalia): new insights from perinatal stages[END_REF], Hautier et al. 2019, pers. obs., turbinals in red in the Fig. 4). The etI is generally the largest ethmo-turbinal and the first ethmo-turbinal that appears in ontogeny [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]. EtI is the olfactory turbinal that reaches the most anterior part of the nasal cavity. In rodents, etI anteriorly originates just before, at the limit or with a small overlap to the respiratory turbinals (Martinez et al. in prep. c).

In other orders such as Eulipotyphla (e.g. shrews and moles), Afrosoricida (e.g. tenrecs), and scandentia (e.g. the treeshrew Ptilocercus lowii), the pars anterior of the etI originates in the anterior part of the respiratory turbinals and highly overlaps them [START_REF] Ruf | The ethmoidal region of the skull of Ptilocerus lowii (Ptiloceridae, Scandentia, Mammalia)a contribution to the reconstruction of the cranial morphotype of primates[END_REF][START_REF] Valkenburg | [END_REF]. In these species and similarly to the naso-turbinal of some species, the etI may have a dual function as a respiratory and olfactory turbinal. Indeed, a part of the pars anterior is covered of respiratory epithelium and the rest is covered by olfactory epithelium (Martinez et al. 2020).

Using histology and micro-CT-scan images, Martinez et al. (2020) identified in most Eulipotyphla and Afrosoricida investigated, a small incisura that may be used to precisely estimate the antero-posterior functional subdivision.

iv. Inter-turbinals

Inter-turbinals are olfactory turbinals that can develop between both fronto-and ethmoturbinals. In rodents, lagomorphs, and Carnivora, inter-turbinals develop later than fronto-and ethmo-turbinals (Ruf 2014, 2020[START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF]. Apparently inter-turbinals never extend as far medially as the fronto-and ethmo-turbinals (Ruf 2020) but some exceptions may occur (Macrini 2012, Martinez et al. in prep. c). In mammals, the number of inter-turbinals varies greatly between species (Paulli 1900, a, b, c, Ruf 2014, Martinez et al. 2018, 2020, in prep. c) and their homology is unclear in some order with highly complex olfactory turbinals (e.g. cingulata or proboscidea, Paulli 1900, a, b, c, Hautier et al. 2019, pers. obs.).

However, one particular inter-turbinal located between ethmo-turbinal I (etI) and II (etII) received more attention and may be homologous in mammals. In the common fronto-ethmoturbinals terminology, this inter-primates (e.g. Ruf 2014, 2020[START_REF] Ruf | The ethmoidal region of the skull of Ptilocerus lowii (Ptiloceridae, Scandentia, Mammalia)a contribution to the reconstruction of the cranial morphotype of primates[END_REF], Martinez et al. 2018, Fig. 1). However, the presence of additional inter-turbinals before this homologous inter-turbinal, complicates the anatomical nomenclature (e.g. [START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF], 2020). These additional inter-turbinals are probably the most variable turbinals in the mammalian clade and do not seem to follow a particular pattern. For example, in rodents, intra-individual (left to right), intra-and inter-specific variations were observed in these additional inter-turbinals (Martinez et al. 2018, in prep. c).

Finally, we must notice that in some rodents, new turbinals have been identified between naso-and maxillo-turbinals and may be also considered as inter-turbinals (Martinez et al. 2020, Martinez et al. in prep. c, Fig. 4).

c. Other terminologies

As usual in anatomy, the finding of clear homology hypotheses is complexified by heterogeneous terminologies that keep continuing to be used [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]) and even to evolve (e.g. with "rostroturbinal" in Macrini 2014). To this problem, we must add the difficulty of identifying certain published errors (see results and discussion in [START_REF] Ito | On the development of the nasal capsule and turbinate homology in Laurasiatherians, with special reference to bats[END_REF], Ruf 2020).

Most variations in employed terminology occured for the olfactory turbinals. In the past, comparative studies of turbinal bones do not have access to precise developmental studies preventing them to identify proper homology (e.g. Le Gros Clark 1951 who named in the rabbit, --turbinals without naming them accurately (e.g. [START_REF] Voit | Das Primordialcranium des Kaningchens[END_REF]. Others used the endo-and ecto-turbinal terminology mixed with reference to the ethmo-tubinal bone (e.g. Paulli 1900a, b, c, Negus 1958).

As an example, [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF] named in Boselaphus tragocamelus (Artiodactyla) the pars anterior of the ethmo-thmo-Tupaia (tree shrew) the pars posterior of the ethmo--Progressively, two terminologies emerged, which have been confronted to one another:

(1) the fronto-, ethmo-turbinal terminology and ( 2) the endo-, ecto-turbinal one (see also discussion of the terminology in [START_REF] Macrini | Comparative morphology of the internal nasal skeleton of adult marsupials based on x-ray computed tomography[END_REF], Maier & Ruf 2014). The fronto-, ethmo-turbinal terminology is mostly based on homology determined by developmental studies, which is the most widespread approach in comparative and systematic studies. The endo-, ecto-turbinal terminology is based on the observation of adult specimens and by the order of appearance of the turbinals. It presents the advantage to be easy to understand and to illustrate, but has rather poor significance in evolutionary biology. This last terminology makes the comparison and discussion about particular turbinals between species difficult. In most cases, ecto-turbinals correspond to the turbinals found in the frontal recess (fronto-and inter-turbinals) whereas endo-turbinals correspond to the rest of olfactory turbinals (lamina semicircularis and ethmo-turbinals) with the exception for some authors of the inter-turbinal located between ethmo-turbinal I (etI) and II (etII, [START_REF] Macrini | Comparative morphology of the internal nasal skeleton of adult marsupials based on x-ray computed tomography[END_REF], but see Paulli 1900, a, b, c). We can also notice that some authors mixed both terminologies (e.g. [START_REF] Rossie | Ontogeny and homology of the paranasal sinuses in Platyrrhini (Mammalia: Primates)[END_REF] or duplicate their captions to be didactic [START_REF] Macrini | Development of the ethmoid in Caluromys philander (Didelphidae, Marsupialia) with a discussion on the homology of the turbinal elements in marsupials[END_REF].

Here (see above), and in the following articles we used the fronto-, ethmo-turbinal terminology which is meaningful from an evolutionary perspective (Fig. 1). We mostly studied groups where some development studies exist and who do not have weird or rather complex olfactory turbinals that would require extensive embryological studies to disentangle a proper terminology. Furthermore, our results will be easily comparable to recent studies (Martinez et al. 2018, 2020, Lundeen & Kirk 2019[START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF], 2020, Ruf 2020[START_REF] Curtis | Maxilloturbinal aids in nasophonation in horseshoe bats (Chiroptera: Rhinolophidae)[END_REF], which employed the fronto-, ethmo-turbinal terminology adapted from Paulli (1900, a, b, c).

However, all these studies do not refer to mammals with complex olfactory turbinals and with a large number of inter-and ethmo-turbinals. Homology of olfactory turbinals is not elucidated in species with highly complex olfactory turbinals such as Carnivora, perissodactyls or anteaters (e.g. Paulli 1900b, Van Valkenburg et al. 2014a, Hautier et al. 2019). Therefore, we must admit that for these species, it may be hazardous to accurately name olfactory turbinals with the fronto-, ethmo-turbinal terminology. However, to date, no recent study investigated the question.

d. Selective pressures affecting turbinals

It was widely hypothesized that the number and the shape of turbinal bones are conserved across orders while their relative size and complexity are more labile, with variation related to species ecology (e.g. Van Valkenburg et al. 2011, 2014a, b, Green et al. 2012[START_REF] Macrini | Comparative morphology of the internal nasal skeleton of adult marsupials based on x-ray computed tomography[END_REF], Ruf 2014, 2020[START_REF] Yee | Comparative morphology and histology of the nasal fossa The[END_REF][START_REF] Curtis | Unique turbinal morphology in horseshoe bats (Chiroptera: Rhinolophidae)[END_REF], Martinez et al. 2018, 2020, Lundeen & Kirk 2019[START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF]. However, few studies have tackled the question using proper statistics, geometric morphometrics, evolutionary models or developmental approaches.

At a higher taxonomic scale, turbinals are thought to carry a phylogenetic signal and several studies identified in turbinal bones potential characters linked to phylogenetic relationships (Paulli 1900a, b, c, Negus 1958). However, in some cases, characters were later found to be wrong. As an example, [START_REF] Gardiner | Tetrapod classification[END_REF] described synapomorphies related to turbinal morphologies that were later refuted (see examples in [START_REF] Gauthier | Amniote phylogeny and the importance of fossils[END_REF]. In mammalian orders or families, the gross turbinal anatomy generally does not significantly vary. For example, Ruf (2020) identified a rodent grundplan for olfactory turbinals that comprises two fronto-turbinals, three ethmo-turbinals, and one inter-turbinal between ethmo-turbinal I and II (see also dog grundplan in [START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF]. [START_REF] Maier | Ontogeny of the nasal capsule in cercopithecoids: a contribution to the comparative and evolutionary morphology of catarrhines[END_REF] also suggested that the marginoturbinal is histological investigation to be properly used in quantitative analysis. This is for example the case of the naked mole rat (Heterocephalus glaber), some porcupines (e.g. Hystrix), or some anomaluromorpha (Martinez et al. in prep. a,c,Fig. 4). Other studies attempted to score some characters in turbinal bones from adult mammals (e.g. [START_REF] Voss | Phylogenetic studies on didelphid marsupials II. Nonmolecular data and new IRBP sequences: separate and combined analyses of didelphine relationships with denser taxon sampling[END_REF][START_REF] Macrini | Comparative morphology of the internal nasal skeleton of adult marsupials based on x-ray computed tomography[END_REF], Ruf 2014, 2020, Lundeen & Kirk 2019). However, at least in rodents the story is more complicated than expected. Indeed, potential characters previously identified as phylogenetically informative, were proven to be wrong or present numerous exceptions with an exhaustive taxon sampling (Martinez et al. in prep. c;Fig. 4). Considering mammals, the shape, complexity and relative size of maxillo-turbinals greatly varies with phylogenetic relationships [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF], Martinez et al. 2020, in prep. a, b, Fig. 7). For example, in Carnivora, Van Valkenburg et al. (2014 a) demonstrated that the complexity of maxillo-turbinal differs between caniforms and feliforms with apparent similar ecologies (e.g. terrestrial).

Developmental constraints are also hypothesized to impact turbinal evolution (e.g. [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]. Indeed, turbinals and other structures or organs may be in conflict for space in the nasal cavity. This hypothesis was widely discussed for eyes and some good evidence may have been found in Carnivora ( Van Valkenburg et al. 2014[START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF]. Rodents have ever growing incisors with roots occupying an important part of the nasal cavity. Therefore, it is likely that the variation of shape and orientation of their incisors constrained the shape and development of turbinals (Martinez et al. in prep c,Fig. 4). The geometric organization of the masticatory apparatus that starts earlier in the development than the ossification of the ethmoid complex, supports this hypothesis (e.g. [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]). However, an example found in the naked mole rat (Heterocephalus glaber) may contradict this hypothesis. Indeed, we identified in the naked mole rat, the loss of the maxillo-turbinal resulting in the presence of a partially empty nasal cavity (Martinez et al. in prep. a). The absence of replacement of this empty space by other structures leads us to assume that there is not a strong conflict for space between different structures in the nasal cavity. An alternative hypothesis is that the loss of this structure is ongoing (as suggested by the intra-individual and intra-specific variations) and that there is a delay between the loss and the replacement of these structures. However, this question needs to be addressed using covariations and / or landmark-based geometric morphometric approaches that remain extremely rare in the field (e.g. [START_REF] Martinez | Convergent evolution and adaptations of fossorial lifestyle: a study of rodents turbinates[END_REF]master thesis, Curtis et al. 2020). Finally, the loss of the maxillo-turbinal in the naked mole rat (Heterocephalus glaber) also suggests that in mammals, maxillo-turbinals may be energetically costly to maintain. Indeed, it is expected that structures or functions that are not costly to maintain may be conserved even if they are no longer under strong selective pressures [START_REF] Jeffery | Adaptive evolution of eye degeneration in the Mexican blind cavefish[END_REF][START_REF] Lahti | Relaxed selection in the wild[END_REF][START_REF] Charles | Under pressure? Dental adaptations to termitophagy and vermivory among mammals[END_REF].

We previously introduced that turbinal bones may vary with phylogenetic relationships and developmental constraints. However, they cannot explain all the differences observed along the mammalian diversity. Indeed, it is now well known that the relative surface area and complexity of turbinals greatly varies with species ecology. In the following two sections, we will discuss the evolution of olfaction and heat and moisture conservation in the light of species ecology. However, our following discussion will be non-exhaustive. Indeed, species ecology have different meanings (e.g. habitat, diet, sociality) and both olfaction and, heat and moisture conservation may be tackled by different approaches (e.g. morphology, histology, genomics) and anatomical proxies (e.g. turbinals, olfactory bulb, vomeronasal organ).

Back to summary

Part II -Olfaction

Picture of Mus mattheyi with superimposed skull and turbinals. Illustration: Quentin Martinez.

From a human perspective

From a human perspective, smell has something mysterious that through invisible particles evokes a remembrance of past things [START_REF] Dugan | The ephemeral history of perfume: Scent and sense in early modern England[END_REF]). As often with unexplained phenomena, mystic interpretations and representations flourished and evolved with societies and cultures. First references of use of products for perfumery may be attributed to ancient Egypt [START_REF] Dugan | The ephemeral history of perfume: Scent and sense in early modern England[END_REF]. In Europe, it mostly developed in ancient Rome then later in France during the eighteen century with the birth of modern perfume industries [START_REF] Dugan | The ephemeral history of perfume: Scent and sense in early modern England[END_REF]). In the Greek myths the women of Lemnos were rejected by their husbands because Aphrodite had caused the women to omit a foul odor. This example reflects how most humans perceive the scent of smell: a nonessential scent that gives them comfort in their daily life. However, anosmia, or the loss of the sense of smell is a psychological trauma where people suffer from depression, eating disorders, or sexual problems (e.g. [START_REF] Toller | Assessing the impact of anosmia: review of a questionnaire's findings[END_REF][START_REF] Boesveldt | Anosmia a clinical review[END_REF]. For example, olfaction plays a key role in the fact that most humans enjoy eating. Indeed, olfaction is responsible for most of what people popularly called taste. However, in medical term, taste is only the discrimination between salt, sweet, sour, bitter, and umami. From a medical perspective, the mix between odors and taste are called flavors. Because the senses of smell and taste have similar receptors, the alteration of the sense of smell will directly affect the sense of taste (e.g. [START_REF] Rouby | Olfaction, taste, and cognition[END_REF][START_REF] Labbe | Impact of olfaction on taste, trigeminal, and texture perceptions[END_REF].

Despite the recent media coverage for this trouble linked to the COVID-19, anosmia has various origins such as injuries, viruses, genetic, or neuronal disorders (e.g. [START_REF] Toller | Assessing the impact of anosmia: review of a questionnaire's findings[END_REF][START_REF] Boesveldt | Anosmia a clinical review[END_REF]. Despite our anthropocentric vision in our industrial world, the scent of smell may have been of major importance in the evolution of the hominid lineage. Indeed, humans discriminate at least 1 trillion olfactory stimuli that is more than the number of colors (several millions) or tones (half a million, [START_REF] Bushdid | Humans can discriminate more than 1 trillion olfactory stimuli[END_REF]). Also, olfactory receptor genes (ORs) form the largest multigene family in the human genome [START_REF] Niimura | Evolution of olfactory receptor genes in the human genome[END_REF].

To date, olfaction is a highly dynamic field. In 2004, Linda B. Buck and Richard Axel received the nobel prize in physiology or medicine for their work on olfactory receptors [START_REF] Buck | A novel multigene family may encode odorant receptors: a molecular basis for odor recognition[END_REF]. Indeed, they participated in the discovery, the estimation, and the description of the olfactory receptor gene superfamily (ORs). For example, they revealed the specialization of the different olfactory receptors that can only detect a limited number of odorant molecules. They also discovered the connection to the olfactory neurons to specific glomeruli from the olfactory bulb that will later process the information in other parts of the brain, allowing for example the association between the odor and a past experience. Therefore, they significantly contributed to clarify our understanding of odor recognition.

Studies on olfactory neurons participated to change long term dogma indicating that neurons are not replaceable in adult vertebrates [START_REF] Graziadei | Neuronal regeneration in frog olfactory system[END_REF][START_REF] Graziadei | Continuous nerve cell renewal in the olfactory system[END_REF]. Indeed, olfactory neurons are naturally replaced during vertebrate adult life but also after injury [START_REF] Graziadei | Continuous nerve cell renewal in the olfactory system[END_REF]. Since these seminal discoveries, other studies demonstrated that these neuronal replacements may have been underestimated through different parts of the nervous system. As an example, neuronal replacement was highlighted in the high vocal center (HVC) of songbirds, a region associated with song learning [START_REF] Alvarez-Buylla | Birth of projection neurons in the higher vocal center of the canary forebrain before, during, and after song learning[END_REF][START_REF] Scharff | Targeted neuronal death affects neuronal replacement and vocal behavior in adult songbirds[END_REF]. In shrews, neuronal number and neocortex width varied with seasons [START_REF] Ray | Seasonal plasticity in the adult somatosensory cortex[END_REF]. The reasons for neuronal replacement are not well understood [START_REF] Nottebohm | Neuronal replacement in adult brain[END_REF] but may be advantageous in the case of olfactory epithelium that is widely exposed to injuries (e.g. [START_REF] Harkema | The nose revisited: a brief review of the comparative structure, function, and toxicologic pathology of the nasal epithelium[END_REF][START_REF] Herbert | Nose, larynx, and trachea[END_REF]. Indeed, it was demonstrated that the nasal cavity and its olfactory pathway was a reservoir but also an entry to the central nervous system for several viruses and pathogens (e.g.

Olfaction in mammals a. Olfactory organs

Paleontological discoveries indicated that early cynodonts may have had low olfactory capacities [START_REF] Rowe | Fossil evidence on origin of the mammalian brain[END_REF]. In comparison to the basal cynodonts (~260 Mya), Morganucodon (~220-200 Mya), has a significant higher encephalization quotient (+ 50%) partially due to the enlargement of the olfactory bulb [START_REF] Rowe | Fossil evidence on origin of the mammalian brain[END_REF]. These observations approximately correspond to the expansion of some ethmo-turbinals [START_REF] Ruf | Nasal anatomy of the non-mammaliaform cynodont Brasilitherium riograndensis (Eucynodontia, Therapsida) reveals new insight into mammalian evolution[END_REF]. Therefore, it is hypothesized that somewhere between 260 and 220 Mya, cynodonts and mammaliaforms started to significantly rely on olfactory cues. Later, a second pulse of encephalization and increase of the olfactory bulb occurred in Hadrocodium (~195 Mya, [START_REF] Rowe | Fossil evidence on origin of the mammalian brain[END_REF]. A third expansion is described with the development of several olfactory turbinals hypothesized to develop in concomitance to the large mammalian repertoire of olfactory receptor genes [START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF][START_REF] Niimura | On the origin and evolution of vertebrate olfactory receptor genes: comparative genome analysis among 23 chordate species[END_REF][START_REF] Rowe | Fossil evidence on origin of the mammalian brain[END_REF]. Extant mammals largely relied on olfaction and centuries of naturalist observations have highlighted a countless number of examples ranging from the detection of a prey scent track, to mating courtship, or defensive behavior [START_REF] Stoddart | The ecology of vertebrate olfaction[END_REF][START_REF] Evans | Vomeronasal chemoreception in vertebrates. A Study of the Second Nose[END_REF]. Some examples also demonstrated that in an odorant world, mammal olfaction might be tricked or impacted by plants and animals (e.g. [START_REF] Miller | An ambusher's arsenal: chemical crypsis in the puff adder (Bitis arietans)[END_REF].

Prior to giving an overview of mammalian olfaction, we need to define what olfactory capacities are (= capabilities). Olfactory performances are mostly discriminated in two major components: (1) the sensitivity (= sensibility, threshold of perception) that is the ability to detect odors at low concentration or at long distance and ( 2) the discrimination that is the ability to distinguish between two similar odors (e.g. Van Valkenburg et al. 2011[START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF]. Some authors

et al. 2005) that is
sometimes defined as the range of odors that can be detected (e.g. Van Valkenburg et al. 2011[START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF]. However, olfactory acuity is sometime inconsistently employed in reference to olfactory discrimination, sensitivity and of the overall olfactory capacities (e.g. Eayrs & Moulton 1960, Moulton et al. 1960[START_REF] Jones | Acute and chronic exposure to ammonia and olfactory acuity for n-butanol in the pig[END_REF][START_REF] Fletcher | Experience modifies olfactory acuity: acetylcholine-dependent learning decreases behavioral generalization between similar odorants[END_REF].

Historically, olfaction was mostly discriminated between two systems: (1) the main olfactory system (including olfactory turbinals) covered by bowman's glands and connected to the main olfactory bulb and ( 2) the vomeronasal organ (= Jacobson's organ or accessory olfactory organ), without bowman's glands and connected to the accessory olfactory bulb (e.g. [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF]). These two systems were hypothesized to participate in the detection of distinct components: volatile odorant molecules for the main olfactory system and non-volatile pheromones for the vomeronasal organ. To date, we know that the distinction of the odorant components is more complex and varied between species. Indeed, it was demonstrated that there exists some bridges between these two olfactory apparatuses. In addition, we currently know that the olfactory system is subdivided in more than two systems (Fig. 5).

As discussed in the first section, the olfactory turbinals are considered as the main olfactory system (with some part of the nasal cavity including roof, floor, and sidewalls). Olfactory neurons from these parts project posteriorly via olfactory nerves through the cribriform plate and join the glomeruli from the main olfactory bulb (Fig. 5). Comparative work demonstrated a relation between the relative size of turbinals and species ecology such as diet (e.g. earthworm consumption, scavengers) or lifestyle (e.g. amphibious, terrestrial, e.g. Van Valkenburg et al. 2004, 2011, 2014a, Green et al. 2012, Martinez et al. 2018, 2020). Based on other studies Van Valkenburg et al. (2011, citing Laska et al. 2005[START_REF] Kowalewsky | High olfactory sensitivity for dimethyl sulphide in harbour seals[END_REF]) hypothesized that the relative surface area of turbinals may not be correlated to olfactory capacity nor sensitivity.

Therefore, they hypothesized that it may characterize the diversity of odorants that can be perceived (herein defined as acuity). However, Martinez et al. (2018) demonstrated that highly specialised worm-eating rodents have significantly higher relative surface area and complexity of olfactory turbinals as compared to their close omnivorous and carnivorous relatives. This gave new insights suggesting that the relative size of olfactory turbinals may be linked to olfactory sensitivity. However, the very small number of studies linking olfactory performance and the relative size of olfactory organs leaves many open questions. Therefore, it might be possible that olfactory proxies based on bony structures inform us on potential olfactory capacities but not on its components namely: sensitivity, acuity, and discrimination. It is likely that it might be essentially impacted by the nature of the olfactory receptors. New evidence will probably emerge from medical studies. Indeed, pathologies of the scent of smell are numerous and include the reduction or the loss of the scent of smell (hyposmia, microsmia, or anosmia), the increase of olfactory sensitivity (hyperosmia), the inability to correctly associated a smell to its nature (parosmia), or even smelling odors that are not actually there (phantosmia). Therefore, by crosschecking the information of these pathologies in relation to neuronal pathways, causes, and organ differences, it will likely be possible to fine tune our knowledge on these olfactory components of the olfactory capacities.

Another well studied organ related to olfaction is the vomeronasal organ. In mammals, the vomeronasal organ is a tubular organ that may be included in a bony or cartilaginous cast in the rostrum (Fig. 5). The vomeronasal organ is mainly composed of olfactory receptors and blood vessels [START_REF] Evans | Vomeronasal chemoreception in vertebrates. A Study of the Second Nose[END_REF]. Olfactory receptors from the vomeronasal organ morphologically differ from those of the main olfactory epithelium [START_REF] Stoddart | The ecology of vertebrate olfaction[END_REF], Villamayor et al. 2018). Its highly vascularized system participates in a pumping mechanism that fills and empties the cavity with air during an active process [START_REF] Allison | The morphology of the olfactory system in the vertebrates[END_REF]. The vomeronasal organ is present or absent in several species without a clearly identified pattern [START_REF] Evans | Vomeronasal chemoreception in vertebrates. A Study of the Second Nose[END_REF]. Species without a vomeronasal organ in the adult stage generally have it early in the development, such as humans [START_REF] Evans | Vomeronasal chemoreception in vertebrates. A Study of the Second Nose[END_REF]. The vomeronasal organ is associated with the spectacular flehmen response (= flehmane, flehman)

well known in Perissodactyla and Carnivora and that consists of curling back the lips to exposed nasopalatine opening (= ductus, canal). This mechanism may facilitate the inhalation of volatile and nonvolatile molecules through the vomeronasal organ and may be seen as a sniffing process in relation to the vomeronasal organ [START_REF] Evans | Vomeronasal chemoreception in vertebrates. A Study of the Second Nose[END_REF]. Not all mammals present the main flehmen response with the curling back of the lips and there is a large diversity of active processes related to this response such as mouth opening, direct contact of the nares, lapping, and tongue protrusion.

The vomeronasal organ allows the detection of pheromones (= intraspecific level) and kairomones (= interspecific level). It has been demonstrated to have an active role in mating preferences, conspecific recognition as well as aggressivity induction [START_REF] Evans | Vomeronasal chemoreception in vertebrates. A Study of the Second Nose[END_REF][START_REF] Chamero | From genes to social communication: molecular sensing by the vomeronasal organ[END_REF]).

Therefore, it plays an important role in sexual and social behaviors. Extensive studies in house mice suggested that the discrimination of major urinary proteins (MUPs) by the vomeronasal organ may be responsible for assortative mating and therefore involves in speciation (e. ) is an olfactory subsystem that was eneberg 1973). This is the smallest of all olfactory organs with for example in mice, a sized range from 300 to 500 cells. It is located anteriorly in the nasal cavity where margino-and atrio-turbinals develop (Fig. 5). In coronal view, the Grueneberg ganglion is located on the dorsal part of the nasal septum with the junction of the wall of the nasal cavity. The Grueneberg ganglion is a cluster of neurons that project posteriorly via olfactory nerves to a specific area of the main olfactory bulb (Fig. 5, [START_REF] Fleischer | Olfactory receptors and signalling elements in the Grueneberg ganglion[END_REF][START_REF] Roppolo | Projection of the Grüneberg ganglion to the mouse olfactory bulb[END_REF], Salazar & Sanchez-Quinteiro 2009). Therefore, some authors have considered this organ to be part of the main olfactory system [START_REF] Storan | Septal organ of Grüneberg is part of the olfactory system[END_REF] but since it also expresses vomeronasal cell types, the question remains open [START_REF] Fleischer | Olfactory receptors and signalling elements in the Grueneberg ganglion[END_REF]. This organ presents a particular morphology for an olfactory organ because the cilia are not visible in the exterior environment and are included in cells that have a permeable envelope (Brechbuhl et al. 2008). The Grueneberg ganglion seems to have a specific role in the detection of the poorly known alarm pheromones (APs, Brechbuhl et al. 2008). These pheromones signal conspecific, injury, distress, or the presence of predators (Brechbuhl et al. 2008). Outside the seminal work of Grueneberg (1973), very few studies attempt to investigate this organ in other species [START_REF] Tachibana | The ultrastructure of the ganglionated nerve plexus in the nasal vestibular mucosa of the musk shrew (Suncus murinus, insectivora)[END_REF], Brechbuhl et al. 2014).

The septal organ is a very small organ located on the ventral part of the nasal septum and posteriorly to the vomeronasal organ (Fig. 5). In the mouse, the septal organ is located ventrally to the anterior part of the pars anterior of the etmo-turbinal I (etI). This organ has a ciliated epithelium with olfactory receptors that project posteriorly to a specific area of the main olfactory bulb (Fig. 5, [START_REF] Ma | Olfactory signal transduction in the mouse septal organ[END_REF]. The septal organ expresses olfactory receptor genes of the main olfactory system and not from the vomeronasal organ [START_REF] Kaluza | Olfactory receptors in the mouse septal organ[END_REF][START_REF] Tian | Molecular organization of the olfactory septal organ[END_REF]).

However, the septal organ is probably the least studied olfactory organ and to date, it is attributed to general odor detection, inducing food detection and social interactions [START_REF] Ma | Encoding olfactory signals via multiple chemosensory systems[END_REF].

The olfactory bulb is a key organ that encodes information that converges from all olfactory organs through olfactory nerves. It is now well known that the olfactory bulb is partitioned in specific areas dedicated to olfactory nerves from different olfactory organs (Fig. 5, Salazar & Sanchez-Quinteiro 2009). This is the case for the main olfactory bulb which is subdivided into specific areas that host olfactory nerves from the Grueneberg ganglion, septal organ, and olfactory turbinals (Fig. 5). The accessory olfactory bulb (AOB) is an area that encodes information from the vomeronasal organ, distinct from the main olfactory process (Fig. 5 Despite some rare exceptions, the brain region and therefore the olfactory bulb is probably the most studied and understood organ related to olfaction.

b. Chemosensory receptors and genes

The discovery of a superfamily of olfactory receptor genes (ORs, [START_REF] Buck | A novel multigene family may encode odorant receptors: a molecular basis for odor recognition[END_REF] was quickly followed by the identification of the vomeronasal receptor gene family (VRs, Dulac & Axel 1995). Later, the raw data of the human genome were simultaneously published by a private company and a public research consortium [START_REF] Venter | Morphological and immunohistochemical study of the rabbit vomeronasal organ[END_REF], International Human Genome Sequencing Consortium 2001). In 2004, a more accurate human genome was available (International Human Genome Sequencing Consortium 2004). To date, the number and the quality of mammalian genomes have increased exponentially, with more than 400 genomes currently available (e.g. Allio et al. 2020 bioRxiv). These resources provide an extraordinary possibility to study the evolution of olfaction.

Chemosensory receptors and therefore genes that coded for these are clustered in four different classes: (1) the olfactory receptors (ORs), ( 2) the vomeronasal receptors (VNRs), ( 3) the trace amine associated receptors (TAARs), and ( 4) the membrane-spanning 4A receptors (MS4As). Olfactory receptors are mostly expressed in the main olfactory epithelium (= olfactory turbinals, septum nasal, sidewalls, roof, and floor of the nasal cavity). They represent the largest olfactory surface within the nasal cavity and for example, as compared to the vomeronasal neuroepithelium. This observation matches with the fact that ORs are the most represented chemosensory receptors in mammals. A gross estimation in 32 mammals gave 1259 ORs genes in mammals [START_REF] Hayden | The molecular biology of vertebrate olfaction[END_REF]. However, ORs gene composition and number highly vary across mammalian phylogeny [START_REF] Niimura | Extensive gains and losses of olfactory receptor genes in mammalian evolution[END_REF][START_REF] Hayden | Ecological adaptation determines functional mammalian olfactory subgenomes[END_REF]) and species ecology (e.g. [START_REF] Kishida | The olfactory receptor gene repertoires in secondary-adapted marine vertebrates: evidence for reduction of the functional proportions in cetaceans[END_REF], 2015, Hayden et Trace amine associated receptors (TAARs) are expressed in the main olfactory epithelium and in the Grueneberg ganglion. They are thought to be involved in social interactions, aversion, and fear detection [START_REF] Dewan | Non-redundant coding of aversive odours in the main olfactory pathway[END_REF][START_REF] Hayden | The molecular biology of vertebrate olfaction[END_REF]. Five TAARs sub-families are known (I to V) and in mice sixteen genes were identified. However, they remain poorly studied in other mammals [START_REF] Hashiguchi | Evolution of trace amine associated receptor (TAAR) gene family in vertebrates: lineagespecific expansions and degradations of a second class of vertebrate chemosensory receptors expressed in the olfactory epithelium[END_REF].

As ORs, Membrane-spanning 4A receptors (MS4As) are also expressed in the main olfactory epithelium. However, they may be marginally expressed and are poorly known. One of their particularities is that they projected posteriorly in an area named the glomeruli) located at the interface between the main olfactory bulb and the accessory olfactory bulb [START_REF] Juilfs | A subset of olfactory neurons that selectively express cGMP-stimulated phosphodiesterase (PDE2) and guanylyl cyclase-D define a unique olfactory signal transduction pathway[END_REF], Shinoda et al. 1989[START_REF] Greer | A family of non-GPCR chemosensors defines an alternative logic for mammalian olfaction[END_REF][START_REF] Poncelet | The evolutionary origins of the vertebrate olfactory system[END_REF].

Despite this apparent distinction of chemosensory receptors, several gene expression and performance studies demonstrated that the clustering is less strict than previously thought.

Therefore, some pheromone-based receptors (e.g. VRs) are known to be expressed in the main olfactory epithelium (e.g. turbinals). Some environmental based receptors (e.g. ORs) are expressed in the accessory olfactory epithelium (e.g. vomeronasal organ, [START_REF] Mandiyan | Deficits in sexual and aggressive behaviors in Cnga2 mutant mice[END_REF][START_REF] Yoon | Olfactory inputs to hypothalamic neurons controlling reproduction and fertility[END_REF][START_REF] Kelliher | The combined role of the main olfactory and vomeronasal systems in social communication in mammals[END_REF][START_REF] Wang | Are pheromones detected through the main olfactory epithelium?[END_REF], Salazar & Sanchez-Quinteiro 2009). However, we do not know if these systems work independently [START_REF] Kelliher | The combined role of the main olfactory and vomeronasal systems in social communication in mammals[END_REF]).

Here we gave an overview of the olfactory organs including olfactory turbinals. However, turbinals also play other important functions such as heat and moisture conservation. Physiological studies related to heat and moisture conservation capacities were legion during the 20 th century but have been rarely linked to respiratory turbinals. As an example, experiments tested and demonstrated physiological performance in many animals (e.g. [START_REF] Martin | Thermal adjustment and respiratory exchange in monotremes and marsupials. A study in the development of homaeothermism[END_REF], Schmidt-Nielsen 1965[START_REF] Collins | A model of respiratory heat transfer in a small mammal[END_REF][START_REF] Whittow | Comparative physiology of thermoregulation[END_REF]. As with olfactory turbinals, the field underwent a renewal with the development of micro-CT [START_REF] Ruben | The metabolic status of some Late Cretaceous dinosaurs[END_REF]. However, since the last decade, the number of studies linking respiratory turbinals to both heat and moisture conservation capacities has drastically decreased. This phenomenon might be partially explained by the retirement or the death of some eminent researchers in the field (e.g. Knut Schmidt-Nielsen 1915 2 -

Respiratory turbinals (= naso-and maxillo-turbinals) are covered with an epithelium that is highly vascularized and made up of several mucus glands. These participate in the warming and humidifying the nasal cavity. In most cases, the inspired air is warmed up and humidified.

During the expiration, the air that came from the respiratory tract is at body temperature and fully saturated with water. The temperature of this expired air will decrease in the contact to the anterior part of the respiratory turbinals that were previously cooled down by the inspired air (e.g. [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Jackson | Countercurrent heat exchange in the respiratory passages[END_REF][START_REF] Collins | A model of respiratory heat transfer in a small mammal[END_REF]. This heat reduction will condensate water from the nasal cavity and allow the expiration of drier air (Fig. 6). Therefore, respiratory turbinals play a key role in heat and moisture conservation. This back and forth exchange system is a widespread physiological system often referred as a countercurrent heat exchange system (Fig. 6, e.g. [START_REF] Jackson | Countercurrent heat exchange in the respiratory passages[END_REF]. In rabbits and in some rodent species, it was properly demonstrated that during inhalation, the maxillo-turbinal participated in increasing temperature through the nasal cavity and reach the body temperature [START_REF] Jackson | Countercurrent heat exchange in the respiratory passages[END_REF][START_REF] Schmidt-Nielsen | The neglected interface: the biology of water as a liquid-gas system[END_REF][START_REF] Schmidt-Nielsen | Counter-current heat exchange in the respiratory passages: effect on water and heat balance[END_REF][START_REF] Caputa | Temperature gradients in the nasal cavity of the rabbit[END_REF]). However, in vertebrates, heat and water saving during exhalation, widely varies between species (Schmidt- [START_REF] Schmidt-Nielsen | Desaturation of exhaled air in camels[END_REF].

Kangaroo rats (Dipodomys spectabilis) live in hot environments where water resources are limited. This species mostly relies on food for its water needs [START_REF] Jackson | Countercurrent heat exchange in the respiratory passages[END_REF]). In the absence of intense activity, sweating evaporation is relatively low, therefore the most important source of water loss is breathing. Several studies demonstrated that this species has more efficient heat and moisture conservation capacities than other species of rodents (e.g.

Rattus norvegicus).

For example, they are able to recover between 54% and 75% of the exhaled water (Schmidt- [START_REF] Schmidt-Nielsen | Counter-current heat exchange in the respiratory passages: effect on water and heat balance[END_REF][START_REF] Schmidt-Nielsen | Desaturation of exhaled air in camels[END_REF][START_REF] Collins | A model of respiratory heat transfer in a small mammal[END_REF]. Surprisingly, they are also able to exhale air 14°C below their body temperature and even below the exterior temperature [START_REF] Jackson | Countercurrent heat exchange in the respiratory passages[END_REF][START_REF] Schmidt-Nielsen | The neglected interface: the biology of water as a liquid-gas system[END_REF]. In a similar environment, experimentations were performed on highly dehydrated camels with presumed drier nasal cavity. They demonstrated that the water saving process works similarly compared to normal conditions (Schmidt- [START_REF] Schmidt-Nielsen | Desaturation of exhaled air in camels[END_REF]. However, in hot environments, variations were observed in the efficiency of respiratory turbinals between day and night. Indeed, camels recovered 70% of the water loss during night exhalation whereas this recovery fell to 25% during the day. Similar variations were observed for heat cooling efficiency. These variations may be explained by the variation in blood pressure intensity and airflow current [START_REF] Langman | Respiratory water and heat loss in camels subjected to dehydration[END_REF][START_REF] Schmidt-Nielsen | Desaturation of exhaled air in camels[END_REF].

Unexpectedly, cold deserts such as in arctic regions have generally drier air than hot deserts (e.g. [START_REF] Langman | Nasal heat exchange in a northern ungulate, the reindeer (Rangifer tarandus)[END_REF]. Experimental studies on reindeer demonstrated that this species exhaled relatively cold and dry air. Therefore, it was estimated that this species was required to drink only 73 ml of water per day (resting at -5 °C, [START_REF] Langman | Nasal heat exchange in a northern ungulate, the reindeer (Rangifer tarandus)[END_REF]. However, if this species had been exhaling saturated and warm air (as humans do) it would require to drink 17 times more (1.24l, Langman 1985). [START_REF] Langman | Nasal heat exchange in a northern ungulate, the reindeer (Rangifer tarandus)[END_REF] also estimated that during expiration, this species recovered 75% of heat that was previously added to the inspired air. Therefore, this species, that experiences drastic climatic conditions, presents some adaptation to save energy. In a similar context, due to the high thermal inertia of water, mammals lose heat quicker in water than in air of the same temperature [START_REF] Molnar | Survival of hypothermia by men immersed in the ocean[END_REF][START_REF] Smith | Skinfolds and resting heat loss in cold air and water: temperature equivalence[END_REF]. Therefore, amphibious and aquatic mammals may be adapted to limit heat loss with for example an efficient heat exchanger (e.g. large respiratory turbinals, Van Valkenburg et al. 2011, Martinez et al. 2020).

To date, the correlation between the relative size of respiratory turbinals and the capacity of heat and moisture conservations was not properly tested. However, preliminary investigation supported this correlation (Martinez et al. in prep. b,Fig. 7). For example, the reindeer (Rangifer tarandus) has the largest relative surface area of maxillo-turbinals (Maxillo RSA) of any investigated mammals (Martinez et al. in prep. a,[START_REF] Hofer | The external anatomy of the oro-nasal region of primates[END_REF]Fig. 7). This arctic species is known to have efficient heat and moisture conservation capacities [START_REF] Langman | Nasal heat exchange in a northern ungulate, the reindeer (Rangifer tarandus)[END_REF]. Similarly, Pinnipedia that are known to have extremely complex and well developed maxillo-turbinals ( Van Valkenburg et al. 2011, Mason et al. 2020, Martinez et al. in prep. b) have a high efficiency in their moisture conservation capacities that may be an adaptation to a salty environment [START_REF] Lester | Water conservation in fasting northern elephant seals (Mirounga angustirostris)[END_REF].

Humans (Homo sapiens) that are known to expire fully saturated air at a temperature close to the body temperature [START_REF] Walker | Heat and water exchange in the respiratory tract[END_REF][START_REF] Schmidt-Nielsen | The neglected interface: the biology of water as a liquid-gas system[END_REF]) have a medium-size Maxillo RSA as compared to other mammalian orders (Martinez et al. in prep. a, b). Finally, the naked mole rat (Heterocephalus glaber) has among the highest evaporative water loss recorded in mammals [START_REF] Collins | A model of respiratory heat transfer in a small mammal[END_REF][START_REF] Buffenstein | Thermoregulation and metabolism in the smallest African gerbil, Gerbillus pusillus[END_REF][START_REF] Buffenstein | Is the naked mole-rat Hererocephalus glaber an endothermic yet poikilothermic mammal?[END_REF] and also the lowest thermoregulatory capacities among terrestrial mammals [START_REF] Martin | Thermal adjustment and respiratory exchange in monotremes and marsupials. A study in the development of homaeothermism[END_REF]. This species presents a unique pattern of the reduction of maxillo-turbinals (Martinez et al. in prep. a, b).

Lastly, a positive correlation was found between metabolic rate and the residuals of respiratory turbinal surface area to body mass (based on 10 species, Owerkowics et al. 2015).

However, using the relative surface area of maxillo-turbinals (Maxillo RSA), preliminary investigations across mammalian orders (424 individuals from 310 species, Martinez et al. in prep. b, Fig. 7) seem to not recover this pattern. This is especially true for species known to have poor temperature regulation, low body temperature and / or low rates of metabolism such as some marsupials, monotremes, Xenarthra and anteaters [START_REF] Martin | Thermal adjustment and respiratory exchange in monotremes and marsupials. A study in the development of homaeothermism[END_REF][START_REF] Wislocki | Location of the testes and body temperature in mammals[END_REF][START_REF] Enger | Heat regulation and metabolism in some tropical mammals and birds[END_REF][START_REF] Mcnab | The metabolism of fossorial rodents: a study of convergence[END_REF].

Despite their additional protective role against abrasive and toxic external elements (e.g. [START_REF] Morgan | Airflow, gas deposition, and lesion distribution in the nasal passages[END_REF][START_REF] Harkema | The nose revisited: a brief review of the comparative structure, function, and toxicologic pathology of the nasal epithelium[END_REF], respiratory turbinals are also assumed to participate in cooling brain temperature via the carotid rete [START_REF] Baker | The influence of the nasal mucosa and the carotid rete upon hypothalamic temperature in sheep[END_REF][START_REF] Langman | Respiratory water and heat loss in camels subjected to dehydration[END_REF][START_REF] Schmidt-Nielsen | Desaturation of exhaled air in camels[END_REF]. As with olfaction, the heat and moisture conservation capacities are multifactorial processes and other factors than turbinals have to be considered. This Finally, despite the title of this PhD thesis and the published papers, we mostly focused our research and our discussion on the olfactory aspect of turbinals. Ongoing and future work will more precisely explore these questions (Martinez et al. in prep. a, b).

Back to summary

Part IV -Discussion and perspectives

Skeleton and turbinals of a young naked mole rat (Heterocephalus glaber). Illustration: Quentin Martinez.

Skeleton and turbinals of a young naked mole rat (Heterocephalus glaber ( ( ). Illustration: Quentin Martinez.

Refining quantification

Since the very beginning of comparative studies on turbinals, authors have described turbinal complexity with their own words (e.g. Paulli 1900, a, b, c, Negus 1958[START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF], Schreider & Raabe 1981[START_REF] Hillenius | The evolution of nasal turbinates and mammalian endothermy[END_REF]). To date, the increasing of turbinal complexity is described as the development of infolding and small lamellae called epiturbinals and resulting from repetitive mesenchymal growth (e.g. Van Valkenburg et al. 2014[START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF]. From a statistical perspective, turbinal complexity is often described as the degree of details in a predefined area (e.g. Martinez et al. 2018). This definition is often considered close to the fractal dimension (or fractal pattern), an index of complexity (e.g. [START_REF] Craven | Reconstruction and morphometric analysis of the nasal airway of the dog (Canis familiaris) and implications regarding olfactory airflow[END_REF], Martinez et al. 2018[START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF]. Turbinal complexity is rarely quantified and always in 2D. Recent methodological advances allow to study the 3D complexity directly on segmented surfaces (Martinez et al. 2018, method developed by Renaud Lebrun and implemented in MorphoDig freeware, www.morphomuseum.com/morphodig, Lebrun 2018). In rodents, results do not significantly change between 2D and 3D methodologies (Martinez et al. 2018). However, in some species, turbinal complexity differs antero-posteriorly, and therefore may be problematic for 2D complexity quantification. Therefore, we recommend the use of 3D complexity that is also more convenient and less sensitive (Martinez et al. 2018, pers. obs.). In rodents, Martinez et al. (2018) demonstrated that there is a significant correlation between complexity and surface area.

However, at least for olfactory turbinals, the significance and the R are low. Nevertheless, the use of one proxy or another in statistical analyses provides similar results. These results support the functional significance of most turbinal studies that only used the surface area proxy.

However, similar work has to be made for all other mammalian clade where strong differences exist. In Monotrema, the surface area of the maxillo-turbinal of the platypus (Ornithorhynchus anatinus) and echidnas (Tachyglossus aculeatus) only differs by a factor of 4 (that is not huge for mammals) but their morphology is remarkably different (Martinez et al. in prep. a b,Fig. 7). The platypus has a very complex maxillo-turbinal with several small lamellae originating from the main three branches, being similar to some Carnivora and aquatic/amphibious species (e.g. Van Valkenburg et al. 2011, Martinez et al. 2020, in prep. b). In contrast, the echidna has no additional lamellae to the main three branches but an unusual thickening that is proportionally thicker than pachyostosis turbinals found in giant and amphibious sloths [START_REF] Amson | Evolutionary adaptation to aquatic lifestyle in extinct sloths can lead to systemic alteration of bone structure[END_REF]. In these examples, complexity tests (e.g. fractal dimension) and work on airflow dynamics may significantly improve our knowledge of how turbinal complexity improves performances. Indeed, we do not know how turbinal complexity changes the airflow dynamics and the odorant deposition. It is known that increasing turbinal surface area will consistently increase the surface area of epithelium and potentially olfactory performance. Based on fluid dynamic principles, Martinez et al. (2018) hypothesized that the increase in turbinal complexity may increase the proportion of air in contact with epithelium. Therefore, the increasing in turbinal complexity may facilitate an increase in air temperature and the absorption of odorant molecules to olfactory receptors.

As previously introduced, the epithelia (e.g. respiratory and olfactory epithelium) do not only line turbinals but the complete nasal cavity that includes turbinals, nasal roof, floor, recess, sidewalls, and laminae [START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF][START_REF] Herbert | Nose, larynx, and trachea[END_REF], Ruf 2020). Therefore, to estimate the intrinsic olfactory, and heat and moisture conservation capacities, we need to precisely estimate the extent of epithelial cover. However, this presents some problems. First, the exact composition and localization of the epithelium is only known in a few species, which is a major methodological limitation while using a micro-CT-scan bony inference. Unlike turbinals or laminae, the nasal roof, floor, and some parts of the sidewalls do not present a clear bony delimitation that matches with their epithelium. Therefore, which bone and how thick a bone structure must be segmented? Even using a mean value based on the mean epithelial thickness covering the nasal cavity, it is likely that there will be significant variation between segmentation sessions and users. Using additional histological data, Martinez et al. (2020) refined the anteroposterior discrimination of the ethmo-turbinal I (etI) in rodents, Afrosoricida, and Eulipotyphla.

However, the inclusion or the exclusion of the anterior part of the pars anterior of the etI, does not significantly affect quantitative results and conclusions (Martinez et al. 2020, pers. obs.).

Similar observations were made with naso-turbinals and the uncinate process of the lamina semicircularis (Martinez et al. 2018(Martinez et al. , 2020, pers. obs.), pers. obs.). Consequently, we believed that the most important in comparative studies is to be consistent. Indeed, in the light of our current knowledge and since some olfactory organs are complicate to quantify, it is very delicate to estimate the true intrinsic size of all structures related to one particular function (e.g. olfaction).

Concerning mammalian brains, the limits of the different anatomical parts are well known and rarely debated. Therefore, analyses using brain endocast volumes or encephalization quotients (EQ) issued from different studies, may be performed with a good degree of confidence.

However, for turbinals where delimitations are still debated and with an important heterogeneity in the quality of scans, we do not recommend to employ turbinal datasets issued from different segmentation sources. Indeed, as other small bony structures, turbinal bones are sensitive to the resolution, the quality of the acquired images, and to the segmentation. Our experience and our control tests in small terrestrial mammals demonstrated that differences are marginal for scans of the skull acquired with a good resolution (pers. obs.). However, for large mammals presenting highly complex olfactory turbinals (e.g. artiodactyls) the scan of the skull is not enough and required a proper scan of their ethmoidal area. For more complex structures such as the cribriform plate and despite the use of different proxies (e.g. the number and the surfaces of holes, the complete surface area, and the surface area from a single view), our personal experience demonstrated that there is an extremely high sensitivity to the resolution, the quality of the acquired images (e.g. contrast, blur or noise) and the segmentation (Hautier et al. 2019, pers. obs.). Indeed, the cribriform plate is a very thin bony structure with sutures only visible in high resolution. In addition to the main large foramina, the cribriform plate is composed of several very small foramina that are only visible with very well acquired images (Fig. 3).

The last aspect of an accurate estimation of the turbinal surface area is the condition of the scanned specimens. Cleaned skulls using dermestid beetles have generally well preserved turbinals [START_REF] Voss | Phylogenetic studies on didelphid marsupials II. Nonmolecular data and new IRBP sequences: separate and combined analyses of didelphine relationships with denser taxon sampling[END_REF] but this is not the case for other methods of preparation (e.g. maceration, boiling). In museums, a significant portion of the skull manually cleaned presents damaged respiratory turbinals. Therefore, it is sometimes challenging to find proper specimens with undamaged turbinals and for some rare species these may not exist. The identification of partially damaged respiratory turbinals may be very delicate in some species or between orders (Martinez et al. in prep. a, b, c, pers. obs.) and therefore, some prior studies used or kept specimens with broken turbinals (e.g. Pang 2017). Also, macroscopic inspection did not always prevent the selection of undamaged specimens. Olfactory turbinals may also be damaged due to trapping methods or brain extraction. In some individuals, agglomerates of dry epithelium may be difficult to discriminate from bony turbinals. The use of fluid preserved heads or full body specimens generally avoids bad surprises, however it will decrease scan quality and resolution.

Lastly, the high number of papers related to turbinals, largely demonstrates the scientific value of this bony structure. However, we must notice that turbinal bones are still employed for DNA extraction, sometimes in rare and historical specimens (Martinez et al. 2018).

Integration

Olfaction is a complicated function relying on multifactorial processes, under many different selective pressures. For example, a single odorant molecule can be detected by a specialized receptor or multiple receptors operating independently or in combination. However, a single olfactory receptor could also bind several odorant molecules. In addition, odorant molecules with different structures may be perceived as a single odor and different odorant molecules with a similar structure may be perceived as different odors (reviewed in [START_REF] Niimura | Olfactory receptor multigene family in vertebrates: from the viewpoint of evolutionary genomics[END_REF][START_REF] Hayden | The molecular biology of vertebrate olfaction[END_REF][START_REF] Yohe | Evolutionary ecology of chemosensation and its role in sensory drive[END_REF]. Therefore, without a clear understanding of the covariation between olfactory organs, it is difficult to confidently discuss the intrinsic olfactory capacities of a species. Concerning mammalian brains, extensive tests were implemented using different brain areas and different anatomical layers (e.g. encephalization, neurons) mainly including the olfactory bulbs both for model and non-model species (e.g. [START_REF] Ribeiro | Greater addition of neurons to the olfactory bulb than to the cerebral cortex of eulipotyphlans but not rodents, afrotherians or primates[END_REF][START_REF] Mcgann | Poor human olfaction is a 19th-century myth[END_REF]. Relative brain volume and other brain proxies, may not always correlate with the actual performance in comparison to more accurate proxies such as neuronal activity or the absolute neuron number (e.g. [START_REF] Herculano-Houzel | The elephant brain in numbers[END_REF][START_REF] Oliveira-Pinto | Sexual dimorphism in the human olfactory bulb: females have more neurons and glial cells than males[END_REF].

Based on alternative non-brain proxies, researchers have discussed patterns related to olfaction (e.g. Martinez et al. 2020). However, few studies have properly tested co-variation between different organs or proxies related to olfaction. One of the first works investigating covariation in olfactory-related organs was probably [START_REF] Bhatnagar | Cribriform plate of ethmoid, olfactory bulb and olfactory acuity in forty species of bats[END_REF]. Using forty species of bats, they found interesting correlations between the number of perforations of the cribriform plate and its surface area, between the diameter of the olfactory bulb and the cerebral hemisphere, and finally between the volume of the olfactory bulb and the surface area of the cribriform plate. Investigating sixteen mammal species, Pihlstrom et al. (2005) found a relation between the surface area of the cribriform plate (estimated by linear measurements) and the surface area of olfactory epithelium of the nasal cavity (therefore, including olfactory turbinals).

Based on eight species, they also found a relation between olfactory sensitivity to butyric acid and the estimated surface area of the cribriform plate. However, this relation turned out to be nonsignificative while considering the relative surface area of the cribriform plate. Because the cribriform plate is linked to the olfactory bulb (being part of the brain endocast), the olfactory sensitivity may be linked to the absolute size of the cribriform plate and the olfactory bulb. Despite the quality of this paper and the fact it became a landmark for the field, we believe that similar work must be done with the current technologies and estimations (see also [START_REF] Bird | Olfaction written in bone: cribriform plate size parallels olfactory receptor gene repertoires in Mammalia[END_REF].

Indeed, the estimation of the cover of olfactory epithelium methodologically differs among studies and it is unclear what is considered as the ethmoid bone. Moreover, since the class of odorant molecules is highly diverse it may not be sufficient to isolate which component of the olfactory performance is related to morphological variation (e.g. sensitivity vs discrimination).

For example, faunivorous mammal predators (e.g. Carnivora, Eulipotyphla, and sanguivorous bats) may be highly sensitive to carboxylic acids whereas frugivorous species (e.g. squirrel monkey) are highly sensitive to acetate and 1,8-cineole (Laska et al. 2000).

In 2014, Garrett & Steiper pushed the boundaries of the field in studying genetic and morphology [START_REF] Garrett | Strong links between genomic and anatomical diversity in both mammalian olfactory chemosensory systems[END_REF]. They found a positive correlation of the absolute size of the cribriform plate (there, named ethmoid bone) and the total number of functional OR genes.

This correlation turned out non-significant while correcting the cribriform plate for size. They did not find a correlation between the functional V1R genes and both the relative and the absolute length of the vomeronasal groove (from the vomeronasal organ). However, they decided to present the positive correlation between the proportion of functional V1R genes (= functional genes / all genes) and the relative length of the vomeronasal groove. In spite of the novelty of this integrative study, several methodological and conceptual problems can be pointed out. First, quantitative data of morphological proxies originated from several different studies with divergent methodological protocols. Then, the study made the inference that linear measurements of the cribriform plate positively correlated with the total surface area of the main olfactory epithelium (therefore based on Pihlstrom et al. 2005). Finally, and this is our major concern, they decided to present (1) the positive correlation between the functional OR genes and the cribriform plate proxy and ( 2) the positive correlation between the proportion of functional V1R genes (= functional genes / all genes) and the vomeronasal organ proxy. Since, there is no correlation between the absolute number of functional V1R genes and the morphological proxy (Garrett & Steiper 2014 supplementary data), the proportion of the functional V1R genes does not provide any information about potential functions and performance. Therefore, the reader needs to carefully read the supplementary data to avoid misinterpretations. Using available data on the olfactory receptor genes (ORs, from [START_REF] Hayden | Ecological adaptation determines functional mammalian olfactory subgenomes[END_REF][START_REF] Matsui | Degeneration of olfactory receptor gene repertories in primates: no direct link to full trichromatic vision[END_REF][START_REF] Hughes | Using Illumina next generation sequencing technologies to sequence multigene families in de novo species[END_REF][START_REF] Montague | Comparative analysis of the domestic cat genome reveals genetic signatures underlying feline biology and domestication[END_REF][START_REF] Niimura | Extreme expansion of the olfactory receptor gene repertoire in African elephants and evolutionary dynamics of orthologous gene groups in 13 placental mammals[END_REF], [START_REF] Bird | Olfaction written in bone: cribriform plate size parallels olfactory receptor gene repertoires in Mammalia[END_REF] demonstrated in 26 mammalian species a correlation between the relative surface area of the cribriform plate and the functional ORs genes. In Carnivora the surface area of the cribriform plate but also the estimated cross section of their foramina correlated with the surface area of the olfactory turbinals [START_REF] Bird | Quantifying the cribriform plate: influences of allometry, function, and phylogeny in Carnivora[END_REF]. Therefore, based on the mammalian correlation between the cribriform plate and the functional olfactory receptor genes (ORs), we may hypothesise that turbinals may correlate with ORs. However, this must be further tested. Indeed, a correlation was found in myrmecophagous mammals between the cribriform plate and olfactory turbinals, but also between the cribriform plate and the respiratory turbinals where no apparent functional hypothesis exists (Hautier et al. 2019). Interestingly, they found similar correlations with the olfactory bulb, the olfactory turbinals, and the cribriform plate (Hautier et al. 2019). Comparing four phyllostomid species, Yohe et al. (2018) described a reduction or loss of the vomeronasal organ. These observations not always matched the pseudogenization of a gene that generally encodes for vomeronasal neuronal transduction (TRPC2). Similarly, they described the covariation between the vomeronasal organ and olfactory turbinals without finding a clear pattern.

Despite some limits, we believe that all these studies significantly contribute to this very complicated field by studying covariation. In addition, we may notice that some organs were never quantified in a comparative and inter-specific approach such as Grueneberg or septal organs and our understanding of the mechanisms is limited. Also, in this section we do not discuss organs related to the heat and moisture conservation capacities. However, it is clear that similar integrative studies may improve our understanding of these functional processes.

Two of our ongoing projects try to refine current functional hypotheses in studying covariation in olfactorynasal cavity of non-model rodents and on the quantification (= semi-quantification) of the olfactory receptors in the olfactory epithelium (Martinez et al. d,Fig. 8). To do so, we worked on fluorescent immunostaining that detects olfactory neurons and their axons (= goat anti olfactory marker protein, OMP, Wako, cat#019-22291, 1:8000). Contrary to classical histology and staining (e.g. HES, hematoxylin, eosin, and safran) where we differentiate epithelia from the morphology and the composition of their cells, immunohistochemistry reveals the expression and provides actual proof of function (e.g. for olfactory neurons in this case). In order to increase the repeatability of the protocol and the accuracy of our results, our goal was to adapt the immunostaining protocol on an automated staining instrument (VENTANA Discovery Ultra, Ventana Medical Systems). We succeeded in the development of the OMP protocol and its adaptation on an automated system in inbreed and wild mice (Fig. 8). We are currently working to adapt it to non-model rodent species with different conditions of tissue fixation. Using this methodology, we will be able to map the nasal cavity of several rodent species across the phylogeny and include in addition, species with contrasted ecological lifestyles. This work may improve our understanding of the variation in mammalian orders and help us to refine quantitative approaches based turbinal proxies. In addition, we should be able to study the neuronal density of homologous areas in order to test the potential correlation with turbinal or epithelial surface area. In collaboration with Marie-Ka Tilak and Rémi Allio, we are currently working on the transcriptomics of olfactory turbinals in two non-model species (Martinez et al. e,Fig. 9). Indeed, Martinez et al. (2020) demonstrated that the amphibious Myocastor coypus has highly reduced olfactory turbinals (= relative surface area and the number of olfactory turbinals) in comparison to one of its close terrestrial relative, the Proechimys genus. Therefore, we sampled olfactory turbinals in Myocastor coypus and Proechimys cuvieri and we succeeded to obtain good quality transcriptomes. These data will allow us to test for potential differential expression of coding genes in the olfactory turbinals. We will test whether these results match the relative surface area of the olfactory turbinals. In addition, we plan to correlate these results with quantitative data extracted from other olfactory-related organs such as the vomeronasal organ, cribriform plate, and olfactory bulb (Fig. 9).

Proofs of concepts and performances

It is common to read in popular press or even in research articles that a particular species has an x time higher scent of smell than another one. For example, in [START_REF] Brooker | Non-visual camouflage[END_REF]:

However, such affirmations are extremely imprecise and complicated to demonstrate. Do the authors refer to the relative size of an olfactory organ or to accurate olfactory performances in sensitivity or discrimination?

The major paradigm of olfaction that persists since more than a century, contrasts macrosmatic and microsmatic organisms (e.g. [START_REF] Turner | The convolutions of the brain: a study in comparative anatomy[END_REF][START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF][START_REF] Stoddart | The ecology of vertebrate olfaction[END_REF]). The first having good olfactory capacities and the latter, poor ones. Following these misleading terms, researchers inconsistently described vertebrates as macrosmatic, and for example contrasted microsmatic birds to the macrosmatic mammals (e.g. [START_REF] Stoddart | The ecology of vertebrate olfaction[END_REF]). One of the most popular of humans. This common affirmation probably originated to the quantification of the olfactory epithelium that lines the nasal cavity (e.g. [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Harkema | Normal morphology of the nasal passages in laboratory rodents[END_REF].

To date, this statement is admitted as a fact and by extension several authors extrapolated it affirming for example that Carnivora and mammals have a good sense of smell (e.g. [START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF][START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF]). However, the question is still highly debated and, in the absence of exhaustive and integrative studies, it remains open (e.g. McGann 2017). As an example, it is true that the relative size of olfactory organs (olfactory turbinals, vomeronasal organs, and olfactory bulbs) significantly differs between dogs and humans (e.g. [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Adams | The canine vomeronasal organ[END_REF]. Moreover, dogs have twice the number of functional olfactory receptor genes compared to humans (Niimura et al. 2017). On the other hand, some olfactory capacities may be linked to the absolute number of neurons and for example, humans have better discriminatory and sensitivity capacities than dogs for particular odorant molecules [START_REF] Herculano-Houzel | The elephant brain in numbers[END_REF], Oliveirapinto et al. 2014[START_REF] Mcgann | Poor human olfaction is a 19th-century myth[END_REF]. Experimental studies in dogs and humans suggested that the apparently poor human olfaction may be partially due to the current absence of behavioral demands. Indeed, humans are able to follow a scent-track as dogs and significantly improved with training [START_REF] Porter | Mechanisms of scent-tracking in humans[END_REF]. Similarly, olfactory performance tests in squirrel monkeys s dis [START_REF] Laska | Olfactory discrimination ability for aliphatic esters in squirrel monkeys and humans[END_REF], Laska et al. 2000). Another good example of these apparent lack of olfactory organs in odontocetes (= toothed whales) that are often considered as anosmic mammals [START_REF] Turner | The convolutions of the brain: a study in comparative anatomy[END_REF][START_REF] Parsons | Anatomy of nasal structures from a comparative viewpoint[END_REF]. However, due to the difficulty of studying odontocetes, these affirmations are based on the gross anatomy and precise anatomical and developmental investigations may tell a different story [START_REF] Klima | Cetacean phylogeny and systematics based on the morphogenesis of the nasal skull[END_REF], 1999[START_REF] Mead | The therian skull: a lexicon with emphasis on the odontocetes[END_REF][START_REF] Berta | Review of the cetacean nose: form, function, and evolution[END_REF]. In addition, it was recently demonstrated that bottlenose dolphins (Tursiops truncatus) may be able to detect and even discriminate olfactory composants, suggesting that they may rely on olfaction for their diet [START_REF] Kremers | Sensory perception in cetaceans: Part II Promising experimental approaches to study chemoreception in dolphins[END_REF][START_REF] Bouchard | Do bottlenose dolphins display behavioural response to fish taste?[END_REF]. In a similar environment, recent discoveries demonstrated that some amphibious shrews and desmans (= Eulipotyphla) are able to detect odorant molecules underwater using bubbling behavior [START_REF] Catania | Underwater 'sniffing' by semi-aquatic mammals[END_REF][START_REF] Catania | Water shrews detect movement, shape, and smell to find prey underwater[END_REF][START_REF] Ivlev | The use of olfaction by the Russian desman (Desmana moschata L.) during underwater swimming[END_REF]. This behavior may be underestimated in amphibious mammals.

Therefore, are these macrosmatic and microsmatic 19th-century terms (Turner 1890) still valid concepts? Probably not (see also Laska et al. 2000[START_REF] Smith | Distribution of olfactory epithelium in the primate nasal cavity: are microsmia and macrosmia valid morphological concepts?. The Anatomical Record Part A: Discoveries in Molecular[END_REF][START_REF] Mcgann | Poor human olfaction is a 19th-century myth[END_REF].

Indeed, it is not too hazardous to realise some comparisons and even extrapolations to potential olfactory capacities between similar organs in relatively closely related taxa (e.g. family, order).

However, is it relevant for highly divergent species, with different ecology, and selective pressures (e.g. shark vs human)? Also, precise terminology (e.g. olfactory performance component or class of odorant molecules) may be used to avoid strong hypothetical interpretations.

In an era where the cost for scanning specimens and acquiring genomic data constantly decreased, the number of available data exponentially increase. The explosion of data in biology and in science in general faced the big challenge of how to handle and analyze them (e.g. Marx 2013). However, it provides us a unique opportunity to unravel the last mysteries of vertebrate rostrum evolution with unprecedented integrative studies. In 2014, Van Valkenburg et al. (2014 this is still the case. (2020) demonstrated a differential pattern between the relative surface area of olfactory turbinals.

b. Les turbines chez les mammifères

Parmi les tétrapodes actuels, les mammifères ont en moyenne les turbines les plus développées (p. ex. [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF], Parson 1971). Malgré quelques études chez les primates, les carnivores, les chauves-souris, les lagomorphes ainsi que les rongeurs, l'homologie des turbines reste floue au sein de certains groupes [START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF]. La difficulté à déterminer l'homologie des turbines est principalement associée aux turbines olfactives (= turbines intervenant dans la détection des odeurs). En effet, l'augmentation de la complexité (= augmentation du nombre de lamelles indépendantes. Même chez les rongeurs, l'homologie des turbines olfactives est parfois incertaine (Martinez et al. es de mammifères (p. ex. Ruf 2004, 2020[START_REF] Smith | Ontogeny and microanatomy of the nasal turbinals in lemuriformes[END_REF], 2020[START_REF] Smith | Nasal fossa of mouse and dwarf lemurs (Primates, Cheirogaleidae)[END_REF][START_REF] Valkenburg | Cependant, peu d'études abordent la question en utilisant des approches statistiques, de A une échelle taxonomique relativement large, les turbines sont supposées être porteuses d'un signal phylogénétique[END_REF].

Les turbines sont généralement divisées en deux catégories : les turbines respiratoires et olfactives. Les turbines respiratoires participent à la conservation de la chaleur et de l'humidité alors que les turbines olfactives interviennent dans les processus de détection des odeurs. Cette discrimination correspond souvent à une localisation antéro-postérieure dans la cavité nasale (Fig. 3).

Les turbines respiratoires sont impliquées dans la conservation de la chaleur et de l'humidité. Lors de l'inhalation, l'air est réchauffé à la température du corps par contact avec la ensément vascularisé. Simultanément, l'air en contact avec le mucus nasal est humidifié. Lors de l'expiration, cet air précédemment réchauffé est désormais refroidi par la partie antérieure des turbines respiratoires qui a été précédemment refroidi par l'air inspiré (Fig. 6). Ce processus condense l'eau des fosses nasales et conserve en moyenne 66 % de l'humidité de l'air expiré [START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Walker | Heat and water exchange in the respiratory tract[END_REF][START_REF] Jackson | Countercurrent heat exchange in the respiratory passages[END_REF][START_REF] Schmidt-Nielsen | Counter-current heat exchange in the respiratory passages: effect on water and heat balance[END_REF][START_REF] Collins | A model of respiratory heat transfer in a small mammal[END_REF][START_REF] Hillenius | The evolution of nasal turbinates and mammalian endothermy[END_REF][START_REF] Ruben | The metabolic status of some Late Cretaceous dinosaurs[END_REF][START_REF] Hillenius | The evolution of endothermy in terrestrial vertebrates: Who? When? Why?[END_REF]). Les turbines respiratoires sont également impliquées dans la protection des voies respiratoires profondes et du neuro-épithélium (= épithélium composé de neurones) des turbines olfactives localisées postérieurement. En effet, les turbines respiratoires filtrent, absorbent et éliminent des éléments macro et microscopiques mais également les composés volatils pouvant provoquer des lésions (p. ex. [START_REF] Morgan | Airflow, gas deposition, and lesion distribution in the nasal passages[END_REF][START_REF] Harkema | The nose revisited: a brief review of the comparative structure, function, and toxicologic pathology of the nasal epithelium[END_REF]. Ces processus sont rendus possibles grâce à la morphologie ciliée de l'épithélium respiratoire mais aussi du fait de ses propriétés d'absorption et de régénération.

Les turbines olfactives participent à la détection des odeurs. En effet, elles sont et [START_REF] Ressler | A zonal organization of odorant receptor gene expression in the olfactory epithelium[END_REF][START_REF] Hillenius | Turbinates in therapsids: evidence for Late Permian origins of mammalian endothermy[END_REF][START_REF] Harkema | The nose revisited: a brief review of the comparative structure, function, and toxicologic pathology of the nasal epithelium[END_REF][START_REF] Barrios | Anatomy, histochemistry, and immunohistochemistry of the olfactory subsystems in mice[END_REF][START_REF] Herbert | Nose, larynx, and trachea[END_REF]. Ces neurones olfactifs sont prolongés ventralement par des axones qui se ramifient et rejoignent des faisceaux de nerfs. Ces nerfs traversent la plaque cribriforme perforée pour rejoindre les glomérules du bulbe cérébral olfactif (Fig. 5). Ainsi, quand une molécule odorante est inspirée, elle est détectée via des récepteurs olfactifs localisés sur les turbines c. Pressions sélectives affectant les turbines Il a été largement admis que le nombre et la forme des turbines sont conservés en fonction turbines pourraient être plus labiles et varier en fonction de l'écologie des espèces (p. ex. Van moyenne par rapport aux autres mammifères (Martinez et al. in prep. b,Fig. 7). Enfin, le rat taupe nu (Heterocephalus glaber aussi de thermorégulation jamais enregistré chez un mammifère [START_REF] Martin | Thermal adjustment and respiratory exchange in monotremes and marsupials. A study in the development of homaeothermism[END_REF][START_REF] Collins | A model of respiratory heat transfer in a small mammal[END_REF][START_REF] Buffenstein | Thermoregulation and metabolism in the smallest African gerbil, Gerbillus pusillus[END_REF][START_REF] Buffenstein | Is the naked mole-rat Hererocephalus glaber an endothermic yet poikilothermic mammal?[END_REF]. Cette espèce présente une perte unique des maxillo-turbines (Martinez et al. in prep. a,[START_REF] Hofer | The external anatomy of the oro-nasal region of primates[END_REF]Fig. 4,7). performances, nous avons apporté de nouvelles évidences quant au rôle fonctionnel des turbines respiratoires (Martinez et al. in prep. a).

mifères (Martinez et al. in prep. b,Fig. 7). En effet, nous essayons de comprendre les facteurs évolutifs qui expliquent les importantes variations observées (p. ex. taille, écologie et relation de parenté entre espèces). Un second projet vise à caractériser l'anatomie des turbines des rongeurs avec un échantillonnage exhaustif comprenant la plupart des sous-familles (Martinez et al. in prep. c,Fig. 4). Ce travail nous permettra de savoir s'il existe réellement des caractères informatifs sur les turbine (Fig. tomographes à rayons X, outils de séquençage par nanopores) et l'explosion des données les processus liés aux fonctions de la cavité nasale.

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Abstract

In most tetrapods, the nasal cavity houses a bony or a cartilaginous system (i.e. turbinals or turbinates) supporting epithelium and sensory organs involved in either olfaction or heat and moisture conservation. Among extant tetrapods, mammals have on average, the largest turbinals to skull length ratio. Despite some studies in primates, Carnivora, bats, lagomorphs as well as rodents, our understanding of the selective pressures affecting turbinals remains imprecise.

This PhD aims to unravel the evolutionary processes responsible for the large anatomical and morphological variations of turbinals among mammals. In the course of our work we acquired an extensive dataset of three-dimensional micro-computed tomography scans (micro-CT) in rodents and other small terrestrial mammals. We were then able to statistically test hypotheses linking turbinal morphology to ecology (e.g. diet or ecotype) and evolutionary patterns such as convergence or evolutionary trade-off (e.g. conflict for space in the nasal cavity between different organs).

The present dissertation provides a non-exhaustive review of the olfaction. In the light of our works, we discussed the methodological and conceptual limits of the field. Indeed, olfaction is a complex function relying on multifactorial processes, under various selective pressures. Olfaction may be tackled by resorting to different approaches (e.g. morphology, histology, genomics) and anatomical proxies (e.g. turbinals, olfactory bulb, vomeronasal organ). In this context, our ongoing projects try to refine current functional hypotheses in studying covariation in olfactory-related organs using different anatomical proxies, immunohistochemistry, and transcriptomic.

Résumé

La plupart des tétrapodes actuels, possède dans leur cavité nasale, des rouleaux osseux que l'on appelle les turbines (= turbinaux). Parmi eux, les mammifères ont en moyenne les turbines les plus développées et, qui sont généralement divisées en deux catégories : les turbines respiratoires et olfactives. Les turbines respiratoires participent à la conservation de la chaleur et de l'humidité alors que les turbines olfactives interviennent dans les processus de détection des odeurs. Malgré quelques études chez les primates, Carnivora, chauves-souris, lagomorphes ainsi que chez les rongeurs, notre compréhension globale des pressions de sélection affectant les turbines reste incomplète.

Cette thèse avait pour objectif de caractériser les facteurs évolutifs expliquant la grande diversité anatomique, morphologique mais également de taille et de complexité des turbines. A destructive, la tomographie à rayons X (= micro-CT), nous avons généré un jeu de données sans précédent sur les turbines de rongeurs et les petits mammifères terrestres. Ainsi, nous avons pu tester statistiquement des hypothèses évolutives en lien avec l'écologie (p. ex. régime alimentaire ou milieu de vie), la convergence (= acquisition la lumière de nos travaux, nous discutons des limites méthodologiques et conceptuelles de ces être abordée par différentes approches méthodologiques (p. ex. morphologie, histologie, génomique) et via différents proxies anatomiques (p. ex. turbines, bulbe olfactif, organe -histochimie et en passant par la transcriptomique.

  Maxillo-turbinals: Mus musculus domesticus (left) and Castor canadensis (right).

Figure 1 :

 1 Figure 1: (Up) Sagittal views of the skull of Mus musculus domesticus with 3D representations of turbinals. Colors follow turbinal homology. (Down) Five coronal sections along the nasal cavity. Figure extracted from Martinez et al. in prep. (c).

Figure 2 :

 2 Figure 2: Exceptional turbinal preservation in fossils. (Left) Sagittal views of the skull of Paradelomys sp. (Theridomyidae, UM-ACQ-6619 Quercy France) with superimposed 3D representations of turbinals. The segmentation of respiratory turbinals is still ongoing. (B) Coronal section of the nasal cavity showing the olfactory turbinals. This rodent probably occurred between the Eocene and the Oligocene ( 33.9 to 28.4 mya). Figure extracted from Martinez et al. in prep. (c).

Figure 3 :

 3 Figure 3: Sagittal views of the skull of Mus musculus domesticus with 3D representations of organs and structures related to olfaction and heat and moisture conservation. (A) Sagittal view of respiratory turbinals (cyan), olfactory turbinals (yellow), cribriform plate (dark blue), olfactory bulb (red), and vomeronasal organ (green). (B) View of the connection between olfactory turbinals, cribriform plate, and olfactory bulb. (C) Posterior view of cribriform plate illustrating the foramina of the olfactory nerves. Illustration: Quentin Martinez.

Figure 4 :

 4 Figure 4: Evolution of turbinals along the rodent phylogeny. Sagittal views of skulls with superimposed 3D representations of turbinals. Ongoing view of the 80 planned species. Colors represent the hypothesised turbinal homologies. Some alternative hypotheses will be presented in the final version. Figure extracted from Martinez et al. in prep. (c).

Figure 5 :

 5 Figure 5: The olfactory system. Grueneberg ganglion (pink), olfactory turbinals (yellow), cribriform plate (dark blue), vomeronasal organ (green), septal organ (red), and their respective nerves connected to the main or the accessory olfactory bulb. Illustration: Quentin Martinez based on Kaluza et al. 2004, Storan & Key 2006, Roppolo et al. 2006, Ekberg et al. 2011, Salazar & Sanchez-Quinteiro 2011.

  g.Smadja & Ganeme 2002[START_REF] Smadja | On the scent of speciation: the chemosensory system and its role in premating isolation[END_REF][START_REF] Hurst | Molecular heterogeneity in major urinary proteins of Mus musculus subspecies: potential candidates involved in speciation[END_REF]. Despite some histological and descriptive works (e.g.[START_REF] Cooper | Comparative anatomy of the vomeronasal organ complex in bats[END_REF][START_REF] Bhatnagar | Development of the vomeronasal organ in Rousettus leschenaulti (Megachiroptera, Pteropodidae)[END_REF], Salazar & Sanchez- Quinteiro 2009, 2011, Villamayor et al. 2018), a proper quantification of the vomeronasal organ is rare in a comparative context(Yohe et al. 2018).The Grueneberg ganglion (GG, = septal organ of Grueneberg (SOG),[START_REF] Storan | Septal organ of Grüneberg is part of the olfactory system[END_REF] terminal endings of the nervus terminalis,[START_REF] Stoddart | The ecology of vertebrate olfaction[END_REF]

  , Larriva-Sahd 2008). The accessory olfactory bulb is probably mostly present in species with a welldeveloped vomeronasal organ (Salazar & Sanchez-Quinteiro 2009, Yohe & Davalos 2018).However, some details about the identification and the presence of the accessory olfactory bulb (even in humans) remain controversial(Larriva-Sahd 2008, Salazar & Sanchez-Quinteiro 2009).

(

  [START_REF] Mezler | Characteristic features and ligand specificity of the two olfactory receptor classes from Xenopus laevis[END_REF][START_REF] Zhang | The olfactory receptor gene superfamily of the mouse[END_REF][START_REF] Hayden | Ecological adaptation determines functional mammalian olfactory subgenomes[END_REF]. As with the turbinal terminology, ORs classification and terminology also differ between authors and the phylogenetic scale of the study[START_REF] Hayden | The molecular biology of vertebrate olfaction[END_REF].Vomeronasal receptors (VNRs) are subdivided in three subfamilies: vomeronasal type-1 receptors (V1Rs), vomeronasal type-2 receptors (V2Rs), and formyl peptide receptors (FPRs).They are mostly expressed in the vomeronasal organ and marginally in the main olfactory epithelium. As previously discussed, VRs are supposed to mostly involve social interactions. The role of the FPRs remains more ambiguous and could be involved in the detection of contaminated compounds such as spoiled food or unhealthy conspecifics(Riviere et al. 2009).

  An amphibious shrew Neomys fodiens preying Phoxinus fayollarum. Illustration: Quentin Martinez. An amphibious shrew Neomys fodiens preying Phoxinus fayollarum. Illustration: Quentin Martinez.

Figure 6 :

 6 Figure 6: Principle of heat and moisture conservation along the respiratory tract. Heat transfers are the result of convection, whereas water transfers are driven by evaporation and condensation. In this example, performances of the respiratory tract allow to save 15°C and 40% of humidity at expiration. Illustration: Quentin Martinez based on Walker & Wells 1961, Jackson & Schmidt-[START_REF] Schmidt-Nielsen | Desert animals: physiological problems of heat and water[END_REF][START_REF] Collins | A model of respiratory heat transfer in a small mammal[END_REF]

  is for example the case of the efficiency of oxygen extraction (Schmidt-Nielsen 1969), body surface evaporation[START_REF] Burch | Rate of insensible perspiration (diffusion of water) locally through living and through dead human skin[END_REF], efficient renal mechanism for water conservation[START_REF] Schmidt-Nielsen | Water balance in a carnivorous desert rodent the grasshopper mouse[END_REF], lung structure (e.g. alveoli and exchange surface,[START_REF] Lester | Water conservation in fasting northern elephant seals (Mirounga angustirostris)[END_REF], or the fur and keratinous cover of the skin.

Figure 7 :

 7 Figure 7: Evolution of maxillo-turbinal at the mammalian scale. Phylogeny of the sampled species with barplots of the relative surface area of maxillo-turbinals (log). Blue and red circles respectively represent the minimum and the maximum logged values from the naked mole rat (Heterocephalus glaber) and the reindeer (Rangifer tarandus). Barplot legend colors: beige = terrestrial, red = arboreal, blue = amphibious, black = subterranean, and yellow = flying species.

Figure

  Figure based on 424 individuals and 310 species and extracted from Martinez et al. in prep. (b).

Figure 8 :

 8 Figure 8: Sagittal sections of the head of Mus musculus domesticus -turbinal III. (A) Haematoxilin-Eosin-Saffron (HES) staining. (B) Superimposition of two fluorescent spectra (cy5 in red and DAPI in blue) from the combination of two antibodies (= multiplex staining, OMP x PCK): the olfactory marker protein (OMP, goat anti OMP Wako, cat#019-22291, 1:8000) and the Pan-Cytokeratin (PanCK). Therefore, olfactory receptors are marked in red and cell nuclei in blue. Figure extracted from Martinez et al. in prep. (d).

Figure 9 :

 9 Figure 9: Ongoing investigation of the covariation between the gene expression (= transcriptomic) of olfactory turbinals and different anatomical proxies related to olfaction. These investigations compare the amphibious Myocastor coypus and the terrestrial Proechimys cuvieri. (A) Heatmap (= cluster analysis) of the gene expression of olfactory turbinals respectively in three and two Myocastor coypus and Proechimys cuvieri. Each line represents a gene and each column a RNA sample. Colors from red to blue indicate the degree of gene expression level from high to low. (B) Sagittal views of the skull of Myocastor coypus and Proechimys cuvieri with 3Drepresentations of organs and structures related to olfaction: vomeronasal organ (green), olfactory turbinals (yellow), cribriform plate (dark blue), and olfactory bulb (red). These preliminary results demonstrated that there is a differential pattern in gene expression of olfactory turbinals between two closely related rodents with different ecological lifestyles. In these species,Martinez et al.

2 .

 2 Objectifs des travaux de thèse Cette thèse avait pour objectif de caractériser les facteurs évolutifs expliquant la grande diversité anatomique, morphologique mais également de taille et de complexité des turbines. Cela res mammifères. Pour ce faire, et provenant de collections de différentes régions géographiques. Les étapes de traitement des scans et notamment la segmentation (= isolation des structures d'intérêt) ont été les travaux les plus chronophages de cette thèse. En effet, ils ont démarré avant la thèse (stages de master 1 et 2) et se sont poursuivis de manière quotidienne au cours des trois années suivantes. Cela nous a données est de pouvoir tester de manière statistique et robuste des hypothèses évolutives telles non directement apparentées) ou de compromis évolutifs (p. ex. conflits entre deux structures ce dans la cavité nasale). Par ces travaux, nous avons pu démontrer statistiquement des adaptations convergentes liées par exemple à la colonisation du milieu aquatique ou à un régime alimentaire hyperspécialisé (Martinez et al. 2018, 2020). Nous avons p et al. 2020). Nous avons proposé une nouvelle méthodologie afin de quantifier la complexité des turbines en 3 dimensions et avons testé sa relation avec la surface relative des turbines (Martinez et al. 2018). Nous avons également permis de raffiner la discrimination antero-posterieure des turbines respiratoires et et al. 2020).

  2). En collaboration avec Nelly Pirot du Réseau d'Histologie Expérimentale de Montpellier, nous travaillons actuellement sur la cartographie de la cavité nasale des rongeurs et sur la quantification (= semi-quantification) des récepteurs olfactifs dans l'épithélium olfactif (Martinez et al. -histochimie qui révèle par fluorescence les neurones olfactifs et leurs axones (Fig. 8). Enfin, en collaboration avec Marieolfactives (= transcriptomique) chez deux espèces de rongeurs non modèles (Martinez et al. e). En effet, Martinez et al. (2020) ont démontré que le ragondin amphibie (Myocastor coypus) possédait des turbines olfactives réduites (= surface relative et nombre de turbines) par rapport à son proche parent terrestre, le rat épineux (Proechimys guyannensis). Nous avons donc échantillonné les turbines olfactives de ces deux espèces proches parents et avons réalisé leurs transcriptomes (Fig. 9). Ces données nous permettront de tester une potentielle expression différentielle des gènes codants dans les turbines olfactives. Nous vérifierons si ces résultats correspondent à ceux obtenus sur la surface relative des turbines olfactives. Dans un second temps, nous comparerons ces proxies avec d'autres organes liés à l'olfaction tels que l'organe voméronasal, la plaque cribriforme et le bulbe cérébral olfactif (Fig. 9). La discussion du manuscrit de thèse présentée ici aborde les limites méthodologiques et domaine (p. ex. sur les performances olfactives), la terminologie non-uniforme des turbines ou encore la sensibilité de certains proxies anatomiques. ar différentes approches méthodologiques (p. ex. morphologie, histologie, génomique) et via différents proxies anatomiques (p. ex. turbines, bulbe olfactif, organe voméronasal). De plus, l'olfaction est une fonction complexe qui repose sur des processus multifactoriels avec des pressions sélectives distinctes. Par exemple, une seule molécule odorante peut être détectée par un seul ou par plusieurs récepteurs olfactifs. Cependant, un seul récepteur olfactif peut également détecter plusieurs molécules odorantes. En outre, des molécules odorantes ayant des structures différentes peuvent être perçues comme une seule odeur et différentes molécules odorantes ayant une structure similaire peuvent être perçues comme des odeurs différentes (Niimura 2012, Hayden & Teeling 2014, Yohe & Brand 2018). Ainsi, l'homme peut distinguer au moins mille milliards de stimuli olfactifs différents (Bushdid et al. 2014). Par conséquent, sans une compréhension claire de la covariation entre les différents organes olfactifs, il est difficile de discuter en toute confiance des capacités olfactives intrinsèques d'une espèce.

  [START_REF] Harberts | Human herpesvirus-6 entry into the central nervous system through the olfactory pathway[END_REF]. Olfactory ensheathing cells (OECs) are the main target for viruses in the nasal cavity and potentially for COVID-19[START_REF] Butowt | SARS-CoV-2: olfaction, brain infection, and the urgent need for clinical samples allowing earlier virus detection[END_REF][START_REF] Yazdanpanah | Anosmia: a missing link in the neuroimmunology of coronavirus disease 2019 (COVID-19)[END_REF]. However, OECs are essential in olfactory neuron

neurogenesis in guiding olfactory axons but also in dead cell clearance (e.g.

[START_REF] Lankford | Olfactory ensheathing cells exhibit unique migratory, phagocytic[END_REF][START_REF] Harberts | Human herpesvirus-6 entry into the central nervous system through the olfactory pathway[END_REF]

. In this context, goblet cells (= mucous glands) may play a key role in protection, enzyme activity, and potential immune response (e.g.

[START_REF] Harkema | The nose revisited: a brief review of the comparative structure, function, and toxicologic pathology of the nasal epithelium[END_REF][START_REF] Birchenough | New developments in goblet cell mucus secretion and function[END_REF][START_REF] Herbert | Nose, larynx, and trachea[END_REF]

). be exhaustively listed herein. For example, research and development links to odors are found in evolution, conservation biology, engineering, agro-industry, pest-control, marketing, and public safety (e.g.

[START_REF] Stoddart | The ecology of vertebrate olfaction[END_REF][START_REF] Hayden | The molecular biology of vertebrate olfaction[END_REF][START_REF] Nielsen | A nose for lizards; can a detection dog locate the endangered pygmy bluetongue lizard (Tiliqua adelaidensis)?[END_REF]

.

  al. 2010[START_REF] Hayden | The molecular biology of vertebrate olfaction[END_REF][START_REF] Hughes | The birth and death of olfactory receptor gene families in mammalian niche adaptation[END_REF], Yohe et al. 2021 bioRxiv, Courcelle et al. in prep.). This is for example the case for diet (e.g.[START_REF] Hayden | The molecular biology of vertebrate olfaction[END_REF][START_REF] Hughes | The birth and death of olfactory receptor gene families in mammalian niche adaptation[END_REF], Yohe et al. 2021 bioRxiv) or lifestyle (e.g.Stathopoulos et al. 2014, Courcelle et al. in prep.). An astonishing number of studies demonstrated that amphibious or aquatic mammals have a larger number of pseudogene and / or

a different ORs genes composition than terrestrial species

[START_REF] Freitag | Olfactory receptors in aquatic and terrestrial vertebrates[END_REF][START_REF] Kishida | The olfactory receptor gene repertoires in secondary-adapted marine vertebrates: evidence for reduction of the functional proportions in cetaceans[END_REF], 2015[START_REF] Niimura | On the origin and evolution of vertebrate olfactory receptor genes: comparative genome analysis among 23 chordate species[END_REF][START_REF] Zhou | Baiji genomes reveal low genetic variability and new insights into secondary aquatic adaptations[END_REF][START_REF] Springer | Inactivation of the olfactory marker protein (OMP) gene in river dolphins and other odontocete cetaceans[END_REF][START_REF] Hughes | The birth and death of olfactory receptor gene families in mammalian niche adaptation[END_REF][START_REF] Beichman | Aquatic adaptation and depleted diversity: a deep dive into the genomes of the sea otter and giant otter[END_REF]

. ORs genes are classified in two major classes (Class I, II) and are supposed to detect general odors such as environmental conditions and food. Class I is composed of four families of ORs genes specialised in water-soluble odorants

[START_REF] Mezler | Characteristic features and ligand specificity of the two olfactory receptor classes from Xenopus laevis[END_REF][START_REF] Zhang | The olfactory receptor gene superfamily of the mouse[END_REF][START_REF] Hayden | Ecological adaptation determines functional mammalian olfactory subgenomes[END_REF]

. Class II is composed of 9 to 15 families specialised in volatile odorants

Article 1 -Convergent evolution of an extreme dietary specialisation, the olfactory system of worm-eating rodents Article 2 -Convergent evolution of olfactory and thermoregulatory capacities in small amphibious mammals

  Beyond the scientific production and life experience of achieving a PhD, the most important thing to me is to thank all those people who during the last years trust in me, help me, inspire me and help me to learn and grow. projets parfois envahissants. Également à ma famille plus élargie ainsi qu'à ma belle-famille.Merci à mes amis sans qui le quotidien ne serait pas le même, notamment : Loic Nouet, RémiAllio, Sergio Ferreira Cardosso, Emmanuel Pontet, Arnaud Aguilar, Vincent Goanec, Gopal Billy, Maxime Goineau, Chrystale Giraud, Celestine Roder. Une pensée toute particulière pour I would like to thank my previous supervisors who always transmit me their unconditional passion for their respective fields: Vincent Vedel, Jean-Pierre Vacher and Antoine Fouquet. A particular thanks to Antoine Fouquet who clearly influenced my career choice and actively en I was ten years old and who later became a friend.Thanks to the ISEM lab that was a wonderful place to work. In this lab all people can interact and collaborate without any hierarchical and social barriers between students, technicians and permanent researchers. Thanks to Nicolas Galtier, head of the ISEM lab who tries to give a new dynamic to the research carried out in the lab by promoting open and ethical science while caring for the future of young researchers. A special thanks for some lab members such as: Renaud Pierre-Henri is a key element who has the intellectual background and the research experience to collaborate and make bridges between two teams and two fields that were before rivals: morphology and genetics. Besides his inspirational integrative scientific work, Pierre-Henri contributed to a variety of scientific fields including biogeography, molecular evolution, phylogeny, taxonomy, paleontology, anatomy, sensory ecology and ecology (and in various organisms such as birds, mammals, and insects). Increasingly rare fact (especially in Europe), he collected raw data during his own scientific expeditions, in sometimes difficult conditions. In 2018, Pierre-Henri almost died in Peru at high elevation. Taxonomy being dear to him, to date, Pierre-Henri described several rodent new species, one new genus and one new subfamily. During a plenary talk given by Pierre-Henri for the Centennial Celebration of the American Society of Mammalogists (ASM), two mammalogists were discussing. Scott J. Steppan Since we met for a bachelor project, and thanks to his unfailing enthusiasm I slowly turned my back on the amphibian world for these beloved rodents. Spoiler alert, rodents are one of the most difficult animal orders to study in the wild. During my PhD, Pierre-Henri gave me all the liberty and the support that I needed to develop the projects that I want, explore different leads

	In the ISEM lab, Is this guy even sleeping?
	Lebrun, Lionel Hautier, Marie-Ka Tilak, Frédéric Delsuc, Julien Claude, François Bonhomme,
	François Catzeflis, Carole Smadja, and Ricardo Araújo.
	I am grateful to all the students I have the chance to supervised or co-supervised on
	various topics such as Benjamin Dubourguier, Mark Wright, Theo Corbet, Elodie Conte, Emilie
	Eveque, Soraya Bengattat, Elisa Emily Davis, and, Arthur Naas.
	Thanks to Marie-Ka Tilak and Remi Allio for their patience and their invaluable work for
	our super integrative project!
	Thanks to Emmanuel Douzery and Maxime Courcelle for their interesting discussions,
	with the hope that we will finish our ongoing project.
	Thanks to Nelly Pirot for her help and interest in our exotic project. Despite surprises and
	setbacks, I b
	for her incredible skills and patience.
	Thanks to all our collaborators. A special thought to Renaud Lebrun, Julien Clavel, Jake
	Esselstyn and Radim Sumbera.
	Thanks to Roberto Portela Miguez, from the Natural History Museum London (NHMUK)
	for his help and trust. Similarly,
	inferna

and start collaborations with different students, researchers and teams. To date Pierre-Henri became a friend much more than a PhD supervisor and I will always be grateful to him for the trust he has placed in me. Hopefully we will do some field work together one day! Finally, I apologize for all those whom I forgot or did not have the space to bring here and yet who mattered to me at one time or another. ai pu oublier. Crocidura suaveolens eating goat moth caterpillar (Cossus cossus); shrew caravaning (Crocidura russula); Mus pahari eating a Locusta sp.; Crocidura russula and its cubs; Mus caroli and its cubs; Arvicola amphibius (fossorial morph) eating some roots; wild Myocastor coypus diving; and Micromys minutus. Pictures: Quentin Martinez and Cécile Molinier.

Extended abstract in French / Résumé étendu en français : Capacités olfactives et thermorégulatrices des petits mammifères terrestres : une étude des turbines nasale

  Dans ce contexte, nous pouvons saluer les éminents travaux de Simon Paulli et de Sir Victor Negus(Paulli 1900 a, b, c, Negus 1958) qui sont devenus des références pour le domaine. 'espèces menacées voire éteintes. Il est également possible d'effectuer des scans à rayons X sur des animaux vivants anesthésiés ou en mouvement (cinéradiographie). L'un des premiers travaux sur les turbines utilisant la microtomographie à rayons X est probablement celuide Ruben et al.

	(1996) qui a étudié les turbines respiratoires chez les oiseaux, les crocodiliens et les théropodes.
	Depuis, le nombre de publications relatives aux turbines a augmenté de façon exponentielle.
	Cependant, la cavité nasale (et donc les turbines) est probablement encore la région la
	moins étudiée	et al.
	2005). Van Valkenburg et son équipe ont largement participé à la démocratisation des analyses
	quantitatives basées sur les turbines (p. ex. Van Valkenburg et al. 2004, 2011, 2014 a, Green et
	1. al.
	Inventée dans les années 80, la tomographie à rayons X (= scanner à rayons X, micro-
	Cette technologie était dans un premier temps extrêmement coûteuse et uniquement consacrée à
	le domaine de l'écologie sensorielle et notamment dans le cas des études sur les turbines. Dans un

a. Les turbines osseuses

Les mammifères ont dans leur cavité nasale, des rouleaux osseux que l'on appelle les turbines (= turbinaux, Fig.

1

). Ces structures participent aux processus olfactifs, à la conservation de la chaleur et de l'humidité, ainsi qu'à la protection des voies respiratoires (p. ex.

[START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF]

.

Les premiers travaux sur les turbines font probablement référence à la médecine humaine où les turbines étaient nommées conques (= conces, p. ex.

[START_REF] Bourgery | Traité complet de l'anatomie de l'homme: comprenant la médecine opératoire, avec planches lithographiées d'après nature[END_REF]

. Au cours des dernières décennies, les turbines ont été largement sous-étudiées par rapport aux autres parties du crâne

[START_REF] Rowe | Organization of the olfactory and respiratory skeleton in the nose of the gray short-tailed opossum Monodelphis domestica[END_REF]

. En effet, étant de fines plaques osseuses perforées, les turbines sont très fragiles et difficiles à extraire du crâne. Les anatomistes des siècles passés ont rivalisé ingéniosité afin de pouvoir accéder à ces structures. Ils ont notamment inventé de fastidieux protocoles de découpe du crâne, réalisés des projections sur transparents, des moulages en plastique ou en métaux ou encore des modèles en carton (p. ex.

[START_REF] Watson | XXV. Further notes on the skull, brain, and organs of special sense of Diademodon[END_REF][START_REF] Dawes | The course of the nasal airstreams[END_REF][START_REF] Negus | The Comparative Anatomy and Physiology of the Nose and Paranasal Sinuses[END_REF][START_REF] Folkow | Anatomical and functional aspects of the nasal mucosal and ophthalmic retia of phocid seals[END_REF][START_REF] Morgan | Airflow, gas deposition, and lesion distribution in the nasal passages[END_REF]

. contexte de diminution drastique de la biodiversité, les spécimens de musées sont devenus rares et de grandes valeurs. Par conséquent, la tomographie à rayons X qui est un processus non destructif, pe dsegmentation (= isolement d'une zone d'intérêt). En effet, chez les mammifères, il faut entre une demi-journée et plusieurs jours pour extraire correctement toutes les turbines d'un côté. Ce processus est encore plus long dans le cas d'images bruitées, pour des scans de fossiles, ou très complexes (p. ex. les espèces amphibies). Dans les prochaines deep learning réduire le temps de segmentation. À ce jour, certains logiciels (p. ex. Biomedisa, Losel et al. 2020) réalisent déjà d'exceptionnels travaux d'interpolation dans des structures telles que les endocastes à des structures aussi complexes et fines que les turbines. croître. Cependant, ces études restent rares chez d'autres tétrapodes (p. ex. oiseaux ou lézards) où la plupart de leurs turbines sont cartilagineuses et donc non visibles aux tomographes à rayons X.

Le récent développement de méthodes de colorations (p. ex. iode ou acide) permet d'améliorer le contraste des tissus mous et donc de les rendre visibles aux tomographes à rayons X

[START_REF] Pauwels | An exploratory study of contrast agents for soft tissue visualization by means of high resolution X[END_REF][START_REF] Gignac | Diffusible metazoan soft tissues[END_REF]

.

Scientific contribution

References

Back to summary

Back to summaryScientific contribution

Scientific contributionScientific contribution

Acknowledgements / Remerciements

Extended abstract in French / Résumé étendu en français :

Acknowledgements / Remerciements

Acknowledgements / Remerciements

Back to summary Article 3 -in preparation -

The mammalian maxilloturbinal evolution: when maxilloturbinal does not reflect thermal abilities

Supplementary informations Article 1

Supplementary informations Article 2

Supplementary informations Article 3

Thanks to Jon Nations, Heru Handika, Amsyari Morni, Finaz, Syam and all other members of the Gunung Murud mission. A special thought for the weird church camp! Thanks to Jake Esselstyn and Pierre-Henri Fabre who let me be part of this mission. Thanks to all the people who contributed to the mouse project. François Bonhomme for his trust and because the project started from his work. Anthony Herrel for his expertise, trust, logistic support, and without whom the project could not have been restarted. Cecile Molinier who accepted and helped the less fun parts of this project and who was an invaluable support for it. Julien Claude and Pierre-Henri Fabre for their logistic support. Remi Allio and Sergio Cardoso for their constant support and trust in the project. Thanks to all our catchers: Sebastien Puechmaille and his family, Severine Berard, Cecile Molinier, Remi Allio, Fabien Condamine, Emmanuel Pontet, Sergio Cardoso, and some anonymous people from Minerve. A very special thought to Anthony Herrel, Remi Allio, and Cecile Molinier who significantly contributed that this project was not abandoned.

Some additional thanks to Sabrina Renaud, Irina Ruf, Fabrice Darinot, Eliane Ramuz, Françoise Poitevin, Emmanuel Desouhant, and Bruno Guinand.

Unconditional thanks to Cecile Molinier, my awesome, adventurer-scientist-partner who has been an unfailing support over the last few years. For five years, we shared field work, wildlife photography and scientific projects. Hopefully, it is just the beginning of a long journey.

How would it be possible to finish my PhD without mentioning my incredible PhD supervisor? In spite of the false brutality of his language and anarchic discourses which may surprise at first sight, Pierre-Henri Fabre is a humanist who altruistically contributed to science and ecology by: participatory science, data collection, financial and logistical support for projects that he does not always co-sign, opening access to these data and giving its time to these students.