Jean-Pierre Suc
email: jeanpierre.suc@gmail.com

Speranta-Maria Popescu

Séverine Fauquette

Mostefa Bessedik

Gonzalo Jiménez-Moreno

Naima Bachiri Taoufiq

Zhuo Zheng

Frederic Medail

Stefan Klotz

Naima Bachiri Taoufiq

Frédéric Médail

Reconstruction of Mediterranean flora, vegetation and climate for the last 23 million years based on an extensive pollen dataset

Keywords: palynology and botany, history of taxa and plant ecosystems, climate quantifications

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

(figure 4). Le domaine sud-méditeranéen était différent avec des environnements ouverts, subdésertiques (avec Lygeum, Calligonum, Neurada, Nitraria, Ziziphus), où Avicennia persista jusqu'au Pliocène inférieur avant l'invasion généralisée par les steppes à Artemisia. Les xérophytes méditerranéennes (Olea, Phillyrea, Ceratonia, Pistacia, Nerium, Quercus type ilex, etc.), présentes dès le début du Miocène, bénéficièrent de cette évolution puis, lors de refroidissements, tirèrent peutêtre partie de certaines phases de grande instabilité dans la saisonnalité et de faible variabilité de la chaleur reçue en relation avec certains paramètres astronomiques (respectivement, forte amplitude de l'obliquité et faible amplitude de l'excentricité) (figures 5-7). Avant sa disparition du domaine nord-méditerranéen, Microtropis fallax (Celastraceae), vivant aujourd'hui dans la forêt sempervirente à larges feuilles du Viêt-Nam mais sous sécheresse estivale, doit être considéré pour illustrer les groupements xérophytiques primitifs. En Camargue, l'expansion des xérophytes méditerranéennes est intervenue plus de 2 000 ans avant les premiers signes d'activité anthropique, apportant un nouvel argument dans le débat sur le rôle respectif du climat et de l'action humaine dans leur récente expansion qui, comme pour les steppes, peut être due d'abord au climat avant d'être encouragée par la pression anthropique (figure 8). L'évolution climatique déduite des flores polliniques peut être subdivisée en trois phases majeures : du Miocène au début du Pliocène supérieur 37 Ma), un certain rythme climatique existait avec une saison sèche (avec des variantes selon l'âge et la situation géographique) dans un contexte subtropical à faible saisonnalité thermique ; la période 3,37 -2,6 Ma peut être regardée comme une phase de transition au cours de laquelle un rythme saisonnier méditerranéen (à sécheresse estivale et froids hivernaux) a été expérimenté ; la mise en place des glaciations de l'hémisphère Nord à 2,6 Ma entraînèrent la généralisation de la xéricité et du froid avec des saisons très contrastées tandis que les interglaciaires étaient plus doux et plus humides. Les quantifications confirment l'existence dès le Miocène moyen d'un gradient latitudinal très marqué, à la fois en température et en sécheresse-humidité (figure 9). Peu après le gradient thermique latitudinal connut une augmentation vers sa valeur actuelle. La by a significant increase in the late Miocene towards its modern value. In the late Pliocene, climate evolved from overall warm temperatures and dry seasons to cooler winters and dry summers. General dryness and colder conditions developed during glacial periods, alternating with moister and warmer conditions during interglacials. Present refuges of Zelkova and Pterocarya are discussed. Desiccation of the Mediterranean led subdesertic plants and cedar to migrate in opposite ways. The present distribution of Cedrus illustrates its weakness against coolings although it seems to have been saved by geodynamic events.

Version abrégée

Cette synthèse, qui repose sur l'analyse de plus de 220 flores polliniques (figure 1), résume trente-sept années de collaboration avec Pierre Quézel (1926Quézel ( -2015)), Professeur à l'univesité d'Aix-Marseille, qui ont été marquées par vingt-huit travaux académiques (table 1). Après un effort unique en vue de l'identification botanique des grains de pollen du Néogène, plus de 260 taxa (dont 74 nouveaux) sont aujourd'hui inventoriés dans le Cénozoïque supérieur de Méditerranée (table 2). Il est désormais démontré qu'il s'agit de la meilleure approche à même de retracer l'histoire de la flore et de la végétation des derniers 23 millions d'années (Ma), favorisant en plus la comparaison avec les macroflores. Cet article se veut un plaidoyer pour l'abandon par quelques palynologues d'une approche inadaptée et dont on devrait mettre en cause la forte homogénéité des résultats incompatible avec l'hétérogénéité des paléoenvironnements. Le caractère diachrone des extinctions de taxa thermophiles et hygrophiles est détaillé selon la latitude et la longitude. Les flores polliniques de Méditerranée nord-occidentale fournissent un exemple significatif des remplacements successifs des écosystèmes végétaux (figures 2 & 3) : la mangrove appauvrie à Avicennia remplacée sur les littoraux du Serravallien par les marécages à Glyptostrobus qui disparaîtront à leur tour au Pliocène ; le relais des forêts sclérophylles par les groupements xérophytiques au Pliocène supérieur ; l'invasion par les steppes à

Introduction

This paper summarizes 37 years of collaboration with Pierre Quézel, former Professor at Aix-Marseilles University and famous specialist of ecology and biogeography of plants in the Mediterranean region [START_REF] Médail | Pierre Quézel (1926-2015), une vie et oeuvre scientifiques entre Méditerranée et Sahara[END_REF], marked by several important papers aiming to decipher the onset of the modern Mediterranean flora, vegetation and climate on the basis of pollen records from the last 23 million years (Ma). Resulting from a new approach to Neogene palynology [START_REF] Suc | A methodology for Neogene palynostratigraphy[END_REF], this synthesis considers more than 220 localities (figure 1) studied within the frame of 29 analytic major analytical works (10 Master theses; 15 PhD theses; 4 State theses) (table 1; see also : Suc et al., 1999;[START_REF] Suc | Pollen records and climatic cycles in the North Mediterranean region since 2.7 Ma[END_REF]Jiménez-Moreno & Suc, 2007;Jiménez-Moreno et al., 2007;[START_REF] Popescu | Pliocene and Lower Pleistocene vegetation and climate changes at the European scale: Long pollen records and climatostratigraphy[END_REF][START_REF] Suc | The Crotone series: A synthesis and new data[END_REF].

Collected data has increased in recent years (e.g.: [START_REF] Jiménez-Moreno | Integrated stratigraphy of the Early Miocene lacustrine deposits of Pag island (SW Croatia): Palaeovegetation and environmental changes in the Dinaride Lake System[END_REF], 2013, 2015;[START_REF] Bertini | Pliocene to Pleistocene palynoflora and vegetation in Italy: State of the art[END_REF][START_REF] Combourieu-Nebout | Climate changes in the central Mediterranean and Italian vegetation dynamics since the Pliocene[END_REF]Suc & Popescu, studies in progress), making this school unquestionably the most suitable one for past reconstructions of the Neogene Mediterranean flora and vegetation. In addition, most of the data are quantified climatically by applying a method based on dessiccation quasi totale de la Méditerranée à la fin du Miocène (5,6 -5,46 Ma) ne s'est pas traduite par des bouleversements climatiques drastiques dans cette région et, du point de vue de la végétation, semble se résumer en l'état de nos connaissances encore partielles (1) à la migration des éléments subdésertiques vers des milieux septentrionaux moins défavorables et (2) à l'opportunité offerte à Cedrus atlantica d'un passage en Afrique du Nord. L'aire relictuelle actuelle de Zelkova (Ulmaceae) est en adéquation complète avec les derniers témoignages polliniques recensés dans le golfe du Lion et en Adriatique centrale. Au contraire, celle de Pterocarya (Juglandaceae) est sujette à discussion. La distribution très disjointe de Cedrus (Pinaceae) est le résultat des vicissitudes climatiques sur le continent eurasiatique où, semble-t-il, trois événements géodynamiques ont permis sa survie (figure 10) : le soulèvement du Tibet pendant l'orogenèse himalayenne pour C. deodara, l'extrusion de la péninsule anatolienne pour C. libani, la dessiccation momentanée de la Méditerranée pour C. atlantica. L'extinction du Cèdre sur le continent nordaméricain demeure par contre très insuffisamment documentée et sans explication si ce n'est à cause des péjorations climatiques qui, pourtant, n'en ont pas éliminé Tsuga. [START_REF] Lobreau-Callen | Présence de pollens de Microtropis fallax (Celastraceae) dans le Pléistocène inférieur de Celleneuve (Hérault)[END_REF][START_REF] Suc | Étude palynologique des marnes de Celleneuve (Pléistocène inférieur)[END_REF][START_REF] Suc | Pollens attribuables aux Agavaceae dans le Pliocène du Languedoc[END_REF]Suc, , 1976aSuc, , 1976bSuc, , 1978aSuc, , 1978b;;[START_REF] Naud | Contribution à l'étude paléofloristique des Coirons (Ardèche): premières analyses polliniques dans les alluvions sous-basaltiques et interbasaltiques de Mirabel (Miocène supérieur)[END_REF][START_REF] Bruguès | Analyse pollinique des dépôts lacustres du Pléistocène inférieur de Banyoles (Bañolas, site de la Bòbila Ordis -Espagne): un élément nouveau dans la reconstitution de l'histoire paléoclimatique des régions méditerranéennes d'Europe occidentale[END_REF][START_REF] Cravatte | Climatic evolution of North-Western Mediterranean area during Pliocene and Early Pleistocene by pollen-analysis and forams of drill Autan 1. Chronostratigraphic correlations[END_REF][START_REF] Bessedik | Le genre Buxus L. (Nagyipollis Kedves 1962) au Tertiaire en Europe occidentale : évolution et implications paléogéographiques[END_REF][START_REF] Suc | Analyse pollinique de lignites néogènes des Landes: Arjuzanx et Hostens (France)[END_REF][START_REF] Bessais | Les écosystèmes végétaux pliocènes de Catalogne méridionale. Variations latitudinales dans le domaine nord-ouest méditerranéen[END_REF][START_REF] Zheng | Végétations et climats néogènes des Alpes maritimes franco-italiennes d'après les données de l'analyse palynologique[END_REF][START_REF] Suc | L'investigation palynologique du Cénozoïque passe par les herbiers[END_REF]Jiménez-Moreno & Suc, 2007;[START_REF] Popescu | Pliocene and Lower Pleistocene vegetation and climate changes at the European scale: Long pollen records and climatostratigraphy[END_REF][START_REF] Biltekin | Anatolia: A long-time plant refuge area documented Graham A[END_REF].

For building synthetic pollen diagrams, taxa are mostly grouped according to a global "ecological niche" corresponding to the mean annual temperature (MAT) under which their present-day representatives are living [START_REF] Nix | Environmental determinants of biogeography and evolution in Terra Australis[END_REF] plus other climatic (mainly linked to xericity) or edaphic considerations, and their status that can be deduced from variations in their pollen records over time ( present-day pollen records and plant distribution (Fauquette et al., 1998a(Fauquette et al., & b, 2007)). This paper does not aim to provide a complete review of all the available pollen data from the Late Cenozoic in the Mediterranean region. The displayed pollen records are all characterized by the same level of quality in identifying pollen grains and can be statistically analyzed as we have all the detailed counts. In particular, the Pleistocene and Holocene times are represented by only few (often long) records, covering the last 2.6 Ma.

Overall, these data are the results of our intense collaboration with Pierre Quézel that justifies this synthesis in the issue dedicated to his memory. After a recap of the main aspects of the methods used, we synthesize the most significant results at the whole Mediterranean scale with focus on (1) floral -vegetation changes, (2) quantified climatic evolution, and (3) biogeographical history of selected taxa.

Methods

Following [START_REF] Zagwijn | Aspects of the Pliocene and Early Pleistocene vegetation in The Netherlands[END_REF] and [START_REF] Pons | Contribution palynologique à l'étude de la flore et de la végétation pliocènes de la région rhodanienne[END_REF], the most impressive palaeoecological progress reached in the 1970's lies in the botanical identification of fossil pollen grains, which was possible due to detailed morphological analyses and accurate comparisons with modern taxa. In this way, identifications are usually done at the genus level for tree pollen with some examples at the species level, and at the family level for herb pollen except for some genera and species. This successful botanical approach severely contrasts with the previously used artificial nomenclature, which unfortunately is still considered by some palynologists for the Neogene (e.g. [START_REF] Bruch | The botanical and the morphological approach in Neogene palynology -a practical comparison[END_REF]Barron et al., 2016). This artificial nomenclature supports the myth of a superficial morphological analysis of the pollen while the botanical approach is based on accurately documented pollen morphology.

In addition, the artificial nomenclature keeps alive the faith in species level identification by using a pseudo-binomial such as Subtriporopollenites simplex (Pot.) Th. & Pf.

or Tetracolporopollenites manifestus (Pot.) Th. & Pf. This method evokes only one simple morphological character (triporate pollen and tetracolporate pollen, respectively) so far from the complex morphological description of any one pollen grain. Sometimes, the used

+ + + + + + 1998a
). The method which also takes into account the modern bioclimatic requirements of taxa (Fauquette et al., 1998b), is built on the statistical comparison between each past pollen assemblage and a database of more than 8,000 modern pollen records from various latitudes and longitudes in the Northern Hemisphere, thus allowing the transposition of the relative abundances of each taxon into climatic values. under various environmental conditions or by considering the low potential of their pollen identification. Additional improvements also contribute to an optimal achievement of pollen analysis such as gentle techniques in processing sediments, mounting of the residue between cover-slip and microscope slide in glycerol (allowing examination of all the pollen faces by rotation and thus its reliable botanical identification), development of extensive photographic databases and modern pollen collections, use of modern pollen atlases, and when necessary examination of the pollen using scanning electron microscope (SEM). Finally, counting of at least 100-150 pollen grains, excluding Pinus because it is often over-represented in marine or lacustrine sediments, makes our palynological approach fully comparable to that performed for late Quaternary studies. The results are shown in synthetic pollen diagrams (with the above mentioned groups), which suitably illustrate the vegetation changes [START_REF] Suc | Origin and evolution of the Mediterranean vegetation and climate in Europe[END_REF]. Most of the studied localities correspond to coastal marine (often prodeltaic) sediments supplied by rivers, which, in addition to their independent dating by marine microplankton, are very appropriate to record the Mediterranean sclerophyllous plants as they inhabited the nearby hinterland. The "Climatic Amplitude Method" was developed to specifically quantify climatic parameters of the Mediterranean lowlands during the Late Cenozoic (Fauquette et al.,

Northwestern Mediterranean vegetation

The Northwestern Mediterranean region is rich in pollen data that can be used successfully for reconstructing the vegetation during the last 23 Ma (figure 1). Pollen counts provide reliable information for estimating palaeovegetation structures and the relative importance of ecological groups, supported by modern pollen records obtained from marine coastal deposits in the Gulf of Lions (Beaudouin et al., 2005b[START_REF] Beaudouin | The significance of pollen signal in present-day marine terrigenous sediments: The example of the Gulf of Lions (western Mediterranean Sea)[END_REF]. Fifty-four localities were selected, distributed from the area between Barcelona and Nice (figure 2) and these are dated from the earliest Miocene to Holocene (figure 3). The following major vegetation changes can be addressed for this region (figure 3): -The impoverished mangrove composed of Avicennia (megatherm element; [START_REF] Bessedik | Une mangrove à Avicennia L. en Méditerranée occidentale au Miocène inférieur et moyen. Implications paléogéographiques[END_REF][START_REF] Bessedik | Le couple récif-mangrove à Sant Pau d'Ordal (Vallès-Penedès, Espagne), témoin du maximum transgressif en Méditerrranée nord-occidentale (Burdigalien supérieur-Langhien inférieur)[END_REF]

Main flora and vegetation changes

Flora

There has been a high diversity and heterogeneity of the Mediterranean flora since the beginning of Miocene, with a lot of megatherm and mega-mesotherm plants in addition to a large pool of taxa still present in the region today (table 2). Extinction of 108 thermophilous and hygrophilous taxa from the Mediterranean region is recorded, mostly during the Miocene and Pliocene, a few during the Quaternary. At the scale of a long-time range as the entire Late Cenozoic, successive extinctions can be regarded to have occurred according to latitude mainly and to longitude secondarily, while some refuge areas were established and persisted up to nowadays [START_REF] Médail | Glacial refugia influence plant diversity patterns in the Mediterranean basin[END_REF][START_REF] Biltekin | Anatolia: A long-time plant refuge area documented Graham A[END_REF]. Basically, extinctions were forced by repeated coolings in the mid-Miocene (13.6 Ma), just after the early-late Pliocene transition (3.6 Ma) and from the earliest Quaternary (onset of the Northern Hemisphere glaciations at 2.6 Ma) (e.g., [START_REF] Svenning | Deterministic Plio-Pleistocene extinctions in the European cool-temperate tree flora[END_REF][START_REF] Suc | L'investigation palynologique du Cénozoïque passe par les herbiers[END_REF]. The Mediterranean physiography is characterized by West-East oriented barriers (mountains, the sea itself, and desert; figure 1). As a consequence, the thermophilous plants could not easily move southward during the climatic deteriorations and recolonize during the warmer phases the spaces previously abandoned. The Mediterranean floral history contrasts to that of North America where natural barriers are North-South oriented. Simultaneously, the East African monsoon exerted some influence that preserved some moisture in the Northeastern Mediterranean region [START_REF] Popescu | Early Pliocene vegetation changes forced by eccentricityprecession: Example from Southwestern Romania[END_REF][START_REF] Suc | Pollen records and climatic cycles in the North Mediterranean region since 2.7 Ma[END_REF][START_REF] Biltekin | Anatolia: A long-time plant refuge area documented Graham A[END_REF]. The Mediterranean sclerophyllous plants (Olea, Ceratonia, Phillyrea, Pistacia, Nerium, Quercus ilex-type, etc.) were already present in the earliest Miocene. According to several syntheses [START_REF] Kovar-Eder | Late Miocene to Early Pliocene vegetation of southern Europe (7-4 Ma) as reflected in the megafossil plant record[END_REF]Barrón et al., 2010;[START_REF] Velitzelos | Review of the Cenozoic floras and vegetation of Greece[END_REF]Martinetto et al., 2015), macrofloras (leaves, fruits, seeds, cuticle, wood) appear richer than pollen floras from the viewpoint of thermophilous taxa which inhabited the Mediterranean region during the Miocene and Pliocene. The macrofloras have, however, a significance mainly restricted to moist places and a relatively limited representation for the herbs. 1976a[START_REF] Suc | Distribution latitudinale et étagement des associations végétales au Cénozoïque supérieur dans l'aire ouest-méditerranéenne[END_REF][START_REF] Bessedik | The early Aquitanian and upper Langhian -lower Serravallian environments in the Northwestern Mediterranean region[END_REF][START_REF] Zheng | Végétations et climats néogènes des Alpes maritimes franco-italiennes d'après les données de l'analyse palynologique[END_REF]Jiménez-Moreno & Suc, 2007). In addition, the high heterogeneity in the Mediterranean physiography [START_REF] Meulenkamp | Tertiary palaeogeography and tectonostratigraphic evolution of the Northern and Southern peri-Tethys platforms and the intermediate domains of the African-Eurasian convergent plate boundary zone[END_REF][START_REF] Jolivet | Lithospheric-scale geodynamic context of the Messinian salinity crisis[END_REF] with coastal reliefs, large islands and/or long peninsulas and episodic wide oceanic connections infers a high diversity of landscapes, supported by a large variety of soils, and therefore probably some mosaic distribution of plant communities. For a large part, the Miocene and Pliocene Northern Mediterranean forests evoke the modern evergreen broad-leaved and mixed mesophytic forests of Southern China [START_REF]The forests of China with a survey of grassland and desert vegetation[END_REF][START_REF] Hou | Vegetation of China with reference to its geographical distribution[END_REF], the pollen representation of which is well-known today [START_REF] Zheng | Comparison of climatic threshold of geographical distribution between dominant plants and surface pollen in China[END_REF][START_REF] Zheng | Comparison of climatic threshold of geographical distribution between dominant plants and surface pollen in China[END_REF]. The Late Cenozoic Southern Mediterranean open vegetation evokes the modern vegetation of the Middle East [START_REF] Zohary | Geobotanical foundations of the Middle East[END_REF][START_REF] White | The Vegetation of Africa[END_REF].

All throughout the last 23 Ma, lands bordering the northern part of the Mediterranean Sea were inhabited by forests while the southern part was occupied by open vegetation, emphasizing the longterm persisting contrast between these realms which probably results from the onset of the Sahara Desert prior to the early Miocene [START_REF] Lancelot | Étude morphologique et radiochronologique de zircons détritiques des flyschs "numidien" et "gresomicacé[END_REF] thesis n° 6, table 1; [START_REF] Suc | Structure of West Mediterranean vegetation and climate since 5.3 Ma[END_REF][START_REF] Fauquette | Latitudinal climatic gradients in Western European and Mediterranean regions from the Mid-Miocene (c. 15 Ma) to the Mid-Pliocene (c. 3.5 Ma) as quantified from pollen data[END_REF]Jiménez-Moreno et al., 2007[START_REF] Bertini | Pliocene to Pleistocene palynoflora and vegetation in Italy: State of the art[END_REF][START_REF] Taoufiq | Les environnements continentaux du corridor rifain (Maroc) au Miocène supérieur d'après la palynologie[END_REF][START_REF] Feddi | Histoire plio-pléistocène des écosystèmes végétaux de Méditerranée sud-occidentale: apport de l'analyse pollinique de deux sondages en mer d'Alboran[END_REF]. Such a contrasting context climatically predisposed the Mediterranean sclerophyllous assemblages in some welldrained environments despite a climatic context that was, on the whole, humid [START_REF] Suc | Neogene vegetation changes in West European and West circum-Mediterranean areas[END_REF].

Vegetation of the entire Mediterranean region

This regional process of major vegetation changes and its timing must be reconsidered at the entire Mediterranean scale (figure 4):

-The Avicennia mangrove disappeared earlier from the North Hungarian -Austrian (i.e. Pannonian) Basin and later from the South Mediterranean shorelines, ending with some residual locations in the southern Black Sea [START_REF] Biltekin | Anatolia: A long-time plant refuge area documented Graham A[END_REF]; -Significantly younger, the disappearance of Glyptostrobus swamps followed in a similar way [START_REF] Biltekin | Anatolia: A long-time plant refuge area documented Graham A[END_REF]; -More or less simultaneously depending of the region, the Artemisia steppe spread over the lands bordering the Mediterranean Basin [START_REF] Suc | Structure of West Mediterranean vegetation and climate since 5.3 Ma[END_REF][START_REF] Popescu | Pliocene and Lower Pleistocene vegetation and climate changes at the European scale: Long pollen records and climatostratigraphy[END_REF][START_REF] Feddi | Histoire plio-pléistocène des écosystèmes végétaux de Méditerranée sud-occidentale: apport de l'analyse pollinique de deux sondages en mer d'Alboran[END_REF]. Such a pattern of the main vegetation changes with a North-South succession implies a latitudinal organisation of the vegetation (i.e. zonation) since the earliest Miocene. The simultaneous presence of meso-microtherm (Cathaya, Cedrus, Tsuga) and microtherm (Abies, Picea) trees attests to an altitudinal belting of vegetation on higher ground (Suc, determinism into those with thermic determinism occurred at around 1 Ma [START_REF] Suc | Structure of West Mediterranean vegetation and climate since 5.3 Ma[END_REF]. This is also the age considered for the onset of modern steppic environments in the Iberian Peninsula (Gonzalez-Sampériz et al., 2010). Improvements are being made in the distinction of Artemisia species or species groups using pollen grains, as initiated by [START_REF] Suc | L'investigation palynologique du Cénozoïque passe par les herbiers[END_REF]. During glacial-interglacial cycles, Artemisia steppes and mesophilous forests were in competition for occupation of the lowlands.

Mediterranean sclerophyllous plants

Early Pliocene pollen floras from the eastern part of the Iberian Peninsula require special attention: they show a latitudinal succession of prevalent taxa among the Mediterranean sclerophyllous plants which resembles the present-day zonation of Mediterranean vegetation. From the Roussillon area southwards to Barcelona, Quercus ilex-type and Phillyrea are indicated by frequent pollen grains with few Olea and Cistus and rare Pistacia (Suc, 1976a;[START_REF] Suc | Étude palynologique du Pliocène de Catalogne (nord-est de l'Espagne)[END_REF].

From Barcelona to south of the Ebre Delta, Olea is prevalent with Phillyrea and Cistus, Quercus ilex-type decreases and Pistacia is better represented in the pollen flora which also includes Nerium [START_REF] Bessais | Les écosystèmes végétaux pliocènes de Catalogne méridionale. Variations latitudinales dans le domaine nord-ouest méditerranéen[END_REF]. Some subdesertic elements, such as Ziziphus, Calligonum, Lygeum and Nitraria are also present and Arecaceae (maybe corresponding to Chamaerops and/or Phoenix p.p.) increase [START_REF] Bessais | Les écosystèmes végétaux pliocènes de Catalogne méridionale. Variations latitudinales dans le domaine nord-ouest méditerranéen[END_REF]. The pollen flora from Andalucia is similar and also includes Ceratonia [START_REF] Feddi | Histoire plio-pléistocène des écosystèmes végétaux de Méditerranée sud-occidentale: apport de l'analyse pollinique de deux sondages en mer d'Alboran[END_REF]. Equally, herbs increase from North to South [START_REF] Jiménez-Moreno | Miocene to Pliocene vegetation reconstruction and climate estimates in the Iberian Peninsula from pollen data[END_REF]. Such a latitudinal succession resembles the presentday replacement of meso-Mediterranean populations by thermo-Mediterranean populations, becoming progressively enriched in subdesertic plants [START_REF] Quézel | Écologie et biogéographie des forêts du bassin méditerranéen[END_REF].

According to pollen records, Mediterranean sclerophyllous plants increased when megamesotherm plants became progressively rarer and then disappeared: it has been hypothesized that sclerophyllous Mediterranean ecosystems somewhat similar to the modern ones developed for the first time in a sustained way between 3.34 and 2.6 Ma [START_REF] Suc | Origin and evolution of the Mediterranean vegetation and climate in Europe[END_REF] but this time-interval is not yet well enough documented by pollen data to allow a detailed reconstruction of vegetation evolution at this time. However, according to Tzedakis Sea to be desiccated as soon as the last gateway connecting to the Atlantic Ocean closed [START_REF] Fauquette | How much did climate force the Messinian salinity crisis? Quantified climatic conditions from pollen records in the Mediterranean region[END_REF] between 5.6 and 5.46 Ma due to tectonic activity (peak of the Messinian Salinity Crisis; [START_REF] Bache | Messinian evaporite deposition during sea level rise in the Gulf of Lions (Western Mediterranean)[END_REF]. Ecological consequences of the sealevel drop of the Mediterranean Sea at this time are still poorly known due to the lack of sedimentary records. However, a significant northward migration of the subdesertic plants is documented as a response to desiccation of the central basins [START_REF] Fauquette | How much did climate force the Messinian salinity crisis? Quantified climatic conditions from pollen records in the Mediterranean region[END_REF][START_REF] Popescu | Earliest Zanclean age for the Colombacci and uppermost Di Tetto formations of the "latest Messinian" northern Apennines: New palaeoenvironmental data from the Maccarone section (Marche Province, Italy)[END_REF]. Only one deep pollen record provides information on the vegetation of desiccated lands near Sardinia at the last evaporitic episode (5.47 Ma): open vegetation rich in halophytes and subdesertic plants with Mediterranean sclerophyllous plants probably inhabited the lowlands while a forest cover existed on the nearby massifs [START_REF] Popescu | Lago Mare episodes around the Messinian-Zanclean boundary in the deep southwestern Mediterranean[END_REF].

Mediterranean steppes

Mediterranean steppes today constitute a crucial topic of discussion, probably because of their duality with respect to their xeric or thermic determinism [START_REF] Quézel | Essais de corrélations phytosociologiques et bioclimatiques entre quelques structures actuelles et passées de la végétation méditerranéenne[END_REF][START_REF] Subally | Glacial or interglacial: Artemisia, a plant indicator with dual responses[END_REF][START_REF] Quézel | Écologie et biogéographie des forêts du bassin méditerranéen[END_REF]. Evidence of steppe assemblages, mainly composed of Ephedra, is rare in the early Miocene of the Northwestern Mediterranean region, as illustrated at Vilobi del Penedès and at La Rierussa (figure 3). Such ecosystems were controlled by a xeric determinism. Later, a first discrete development of the Anatolian steppes, composed of Artemisia mainly and Ephedra, occurred at about 6.2 Ma and was followed by more pronounced expansion at 5.8 -5.6 Ma, probably related to Antarctic glaciation and later with the desiccation phase of the Mediterranean Sea [START_REF] Popescu | Late Miocene and early Pliocene environments in the southwestern Black Sea region from high-resolution palynology of DSDP Site 380A (leg 42B)[END_REF][START_REF] Popescu | Pliocene and Lower Pleistocene vegetation and climate changes at the European scale: Long pollen records and climatostratigraphy[END_REF][START_REF] Popescu | Objective utilization of data from DSDP Site 380 (Black Sea)[END_REF]. At 5.2 Ma, Anatolian steppes crossed a critical threshold in their spreading that probably transformed them into a "regional pool" for their forthcoming wide expansion around the Mediterranean Sea [START_REF] Popescu | Late Miocene and early Pliocene environments in the southwestern Black Sea region from high-resolution palynology of DSDP Site 380A (leg 42B)[END_REF][START_REF] Popescu | Pliocene and Lower Pleistocene vegetation and climate changes at the European scale: Long pollen records and climatostratigraphy[END_REF][START_REF] Popescu | Objective utilization of data from DSDP Site 380 (Black Sea)[END_REF]. This affected the southern Mediterranean region at 3.34 Ma, related to cooling following the Zanclean -Piacenzian transition, then the northern Mediterranean region at 2.6 Ma when the Northern Hemisphere glaciations commenced (figure 4). As shown by some plants associated with Artemisia -Ephedra steppes, the turnover from steppes with xeric Time-interval 3.6 -0.9 Ma (figure 6):

-peaks 'a -c' coincide with relative minima of the ratio of "thermophilous/steppe elements" and are thus correlated with cooler phases corresponding to marine isotope stages (MIS) M2, KM2 and G10, respectively; -location of peak 'd' is somewhat ambiguous as it coincides with a minor maximum of the ratio of "thermophilous/steppe elements" within a general lowering trend, and is correlated with the warmer MIS G3; -the cluster of peaks 'e' corresponds for the most prominent peaks to a colder phase identified as MIS 98; -the cluster 'f' shows its most important maxima in its upper part, i.e. in correspondence with the minimum of the ratio of "thermophilous/steppe elements" correlated with MIS 86; -the most important peaks of cluster 'g' belong to a colder phase correlated with MIS 82; -cluster 'h' is located within a minor cooling during a warm phase identified as MIS 45; -cluster 'i' shows its major peaks located within a warmer phase correlated with MIS 39 while minor peaks correspond to a cooling correlated with MIS 38; -at least two isolated peaks (between 'e' and 'f' and above 'i') correspond to coolings, MIS 90 and 36 respectively.

(2007), several transient episodes with the Mediterranean seasonal pattern of rainfall may have occurred before the Pliocene that progressively led the sclerophyllous plants becoming more adapted to a dry season. Conversely, data for analysing the development of the Mediterranean sclerophyllous ecosystems during glacial-interglacial cycles are abundant for the last 2.5 Ma. A lot of surface marine, lagoonal or lacustrine sediments from the Northwestern Mediterranean region illustrate that nowadays the Mediterranean sclerophyllous plants account for between 3 and 28% of the total pollen sum (Pinus excluded) [START_REF] Cambon | Modern pollen deposition in the Rhône delta area (lagoonal and marine sediments), France[END_REF][START_REF] Dantec | Évolution floristique des abords de la mare de Grammont (Montpellier, sud de la France) depuis un siècle: disparition d'Isoetes setacea Lam[END_REF][START_REF] Suc | Neogene vegetation changes in West European and West circum-Mediterranean areas[END_REF][START_REF] Beaudouin | The significance of pollen signal in present-day marine terrigenous sediments: The example of the Gulf of Lions (western Mediterranean Sea)[END_REF]. A borehole covering the years 1950-1991, cored in the Rhône prodelta where sedimentation rate is fast (ca. 60 cm/year in the absence of disturbances as storms and/or floods), shows that the seasonal representation of Mediterranean sclerophyllous plants during their blooming period comprised between 3.79 and 8.52% of the total pollen sum, Pinus being excluded (Beaudouin et al., 2005b).

Considering the large surface nowadays occupied by the meso-Mediterranean vegetation back of coastal ecosystems in Southern France, it is obvious that Mediterranean sclerophyllous plants are under-represented in coastal marine or lagoonal sediments. Therefore, we consider that a value higher than 3% in past pollen records is significant, outweighing potential biases due to pollen transport and/or preservation, and means an important development of Mediterranean sclerophyllous plants. In order to determine the relationship which may have existed since 3.6 Ma between climate evolution and development of the Mediterranean vegetation, we use the percentage curves in 13 accurately dated pollen localities (figure 5). These curves are plotted using the pollen ratio of "thermophilous/steppe elements" (figures 6-8), which is a reliable index of climatic changes in lowlands of the Mediterranean region as shown by long records, and correlated with reference to the oxygen isotope curve [START_REF] Popescu | Pliocene and Lower Pleistocene vegetation and climate changes at the European scale: Long pollen records and climatostratigraphy[END_REF][START_REF] Joannin | Vegetation changes during the late Early Pleistocene at Montalbano Jonico (province of Matera, southern Italy) based on pollen analysis[END_REF][START_REF] Suc | The Crotone series: A synthesis and new data[END_REF]. Special attention is paid to significant peaks (>3%) of the Mediterranean sclerophyllous plants in figures 6-8, indicated by grey bands.

In particular, the isolated peaks significantly greater than 3% and those grouped in clusters, even though of brief duration, are examined (indexed 'a -i' in figure 6; 'j -l' in figure 7; 'm -r' in figure 8): and are related to decreases in the GISP2 record at ca. 10,200, 8,700, 7,200 and 5,200 yrs cal. BP, respectively. For the interval 3.6 -0.9 Ma, the peaks or clusters are irregularly paced, but most of them occurred during periods with decreases in temperature (figure 6). In the Garraf 1 record, the main pollen contributors to peaks 'a-d' are Olea, Phillyrea and evergreen Quercus [START_REF] Suc | Étude palynologique du Pliocène de Catalogne (nord-est de l'Espagne)[END_REF]. In the lower part of the Crotone series (peaks 'e-g'), they are Pistacia, Olea and evergreen Quercus; in its upper part (peak 'h'), Olea and evergreen Quercus [START_REF] Combourieu-Nebout | Les cycles glaciairesinterglaciaires en région méditerranéenne de 2,4 à 1,1 Ma : analyse pollinique de la série de Crotone (Italie méridionale)[END_REF]). In the Camerota record [START_REF] Brenac | Végétation et climat de la Campanie du Sud (Italie) au Pliocène final d'après l'analyse pollinique des dépôts de Camerota[END_REF], the warm phase (lower part of cluster 'i') shows a predominance of Ceratonia and Olea replaced by that of Olea, Phillyrea and evergreen Quercus; the following cooler phase (middle part of cluster 'i') displays a minimum occurrence of Olea and evergreen Quercus; the uppermost warming phase (uppermost part of cluster 'i'), shows a minor presence of evergreen Quercus. Olea is the main component of the minor peak of the lowermost part of the Montalbano Jonico series [START_REF] Joannin | Vegetation changes during the late Early Pleistocene at Montalbano Jonico (province of Matera, southern Italy) based on pollen analysis[END_REF]. Peaks or clusters from the interval 640 -15 ka are also irregularly paced; some of them can be referred to a cooling period, others to a warming phase (figure 7). The upper interglacial phase of Vallo di Diano (cluster 'j') shows predominance of evergreen Quercus and, at a lesser level, of Pistacia and Olea (Russo [START_REF] Ermolli | Analyse pollinique de la succession lacustre pléistocène du Vallo di Diano (Campanie, Italie)[END_REF]. In the PRGL1-4 record, clusters 'k' and 'l' and secondary peaks show predominantly Olea, Phillyrea and evergreen Quercus (Suc et al., in progress). Most of the isolated peaks and clusters from the interval 11,200 -0 years are correlated with cooler episodes (figure 8). Evergreen Quercus prevails in the isolated peaks and in clusters 'm -o'. Subsequently, Olea and sometimes evergreen Quercus or Phillyrea are the most important representatives of Mediterranean sclerophyllous plants in clusters 'p -r'. In a first approximation, it seems that the Mediterranean sclerophyllous plants were advantaged during cooling phases, maybe because of the opening of forested vegetation. However, these isolated peaks or clusters are not uniformly distributed through time (figures 6-8), indicating that temperature falls and correlative dryness increases are not the only forcings. Indeed, there is no direct relationship with the insolation curve at 60°N Time-interval 640 -15 ka (figure 7): -cluster 'j' coincides with a warm period correlated with MIS 13; -cluster 'k' corresponds to a cold phase correlated with MIS 12; -cluster 'l' shows its minor peaks during a warm phase correlated with MIS 9 and its major peak during a warmer episode within MIS 8; -an isolated peak between clusters 'k' and 'l' belongs to a cold phase related to early MIS 10; -the three isolated and minor peaks following cluster 'l' occurred during moderate warmings within cold MIS 8 (lower peak) and MIS 6 (two upper peaks); -the last isolated minor peak is recorded in correspondence with a moderate warming correlated with MIS 5c (i.e. the Saint-Germain 1 interstadial).

Time-interval 11,200 -0 years for which climatic correlations are made with reference to the Greenland isotope curve GISP2 (figure 8):

-cluster 'm' is located during a phase of weak decrease in temperature correlated with a transitional phase in the GISP2 curve characterized by low fluctuations around 4,500 yrs cal. BP; -each of the three peaks of cluster 'n' match a cooler episode within a fluctuating period with prevalent cooler episodes in the GISP2 curve between 4,000 and 3,600 yrs cal. BP; -the same observation is made for most of the peaks of cluster 'o' in relation with a phase of greater amplitude fluctuations in the GISP2 curve between ca. 3,500 and 2,900 yrs cal. BP; -a similar interpretation concerns peaks of cluster 'p' equating, on the whole, to a cooler period corresponding to prevalent coolings in the GISP2 curve (2,300 -1,700 yrs cal. BP); -the two peaks of cluster 'q' correspond to a cooling trend expressed by the ratio of "thermophilous/steppe elements" and to repeated decreases in temperature in the GISP2 record between 800 and 500 yrs cal. BP; -peaks of cluster 'r' resemble those of cluster 'p' and are correlated with a cooler phase in the GISP2 curve between 400 and 200 yrs BP; -the four isolated peaks before cluster 'm' match relative cooler phases according to the ratio of "thermophilous/steppe elements" heat (low amplitude of eccentricity) [START_REF] Berger | Paleo-insolation at the Plio-Pleistocene boundary[END_REF] may have advantaged the Mediterranean sclerophyllous plants competing with other ecosystems within opening low altitude landscapes during colder periods. Mediteranean sclerophyllous ecosystems were widely developed in the Southen Italian Peninsula but some correlations coincide with phases of relative higher amplitude of obliquity and simultaneously with phases of relative lower amplitude of eccentricity: e.g. peaks or clusters 'c -g', 'i' and 'k' (figures 6-7). Such phases of increased instability in seasonality (high amplitude of obliquity) and low variability in 1. Same explanations as for Figure 6 without the eccentricity and obliquity amplitudes not illustrated here.

, 2005a); 92K08 and 92K04 (thesis n° 1), Piton (thesis n° 3); Saint-Ferréol (thesis n° 11), BF6 (thesis n° 27) -thesis references are in Table

(figure 7; [START_REF] Laskar | A long-term numerical solution for the insolation quantities of the Earth[END_REF]. As an additional argument, we emphasize that Olea pollen is abundant in the youngest records from 92K08 and 92K04 cores (location in figure 5). These results highlight that pollen analyses at high time resolution are strongly needed. The evolution of Mediterranean vegetation during the last 23 Ma can be summarized as follows: surface reduction of some plant ecosystems was counterbalanced by the spread of other ones: Avicennia mangrove vs. Glyptostrobus swamps, evergreen subtropical forests vs. Mediterranean sclerophyllous ecosystems, herb ecosystems vs. Artemisia steppes, and lastly mesophilous forests vs. Artemisia steppes during climatic cycles.

Climatic evolution

The climatic evolution of the Mediterranean region can be synthetically subdivided into three major phases:

-During the entire Miocene, the early Pliocene and the beginning of late Pliocene (i.e., from 23 to 3.37 Ma), a climatic rhythm existed with some seasonal dryness that could vary according to age and geography; low amplitude in seasonal temperature variation is also assumed in a subtropical context [START_REF] Bessedik | The early Aquitanian and upper Langhian -lower Serravallian environments in the Northwestern Mediterranean region[END_REF]Jiménez-Moreno & Suc, 2007;Jiménez-Moreno et al., 2007); -The time interval 3.37 -2.6 Ma can be regarded as a transitional period characterized by the emergence of a Mediterranean seasonal rhythm with summer drought and cooler winters [START_REF] Suc | Origin and evolution of the Mediterranean vegetation and climate in Europe[END_REF][START_REF] Popescu | Pliocene and Lower Pleistocene vegetation and climate changes at the European scale: Long pollen records and climatostratigraphy[END_REF]; -From 2.6 Ma, the earliest glaciations in the Northern Hemisphere caused generalized dryness and colder conditions during glacials with highly contrasting seasons. On the contrary, moister and warmer conditions developed during interglacials. Such climatic trends were repeated during secondary fluctuations (Suc, 1978;[START_REF] Combourieu-Nebout | What was the late Pliocene Mediterranean climate like: a preliminary quantification from vegetation[END_REF]. A strong North-South gradient was continuously superimposed on this general context, characterized by a southward dryness and temperature increase during warmer periods, and a decreasing climatic contrast during colder periods [START_REF] Suc | Structure of West Mediterranean vegetation and climate since 5.3 Ma[END_REF]Jiménez-Moreno & Suc, 2007). Palaeoclimatic quantifications allow an estimation of this dual between 2.6 and 1.2 Ma as illustrated by the Crotone and Camerota successions (figure 6). Pollen records from Crotone and Montalbano Jonico document a similar palaeoclimatic evolution to those from Camerota and Vallo di Diano although their sedimentary context differs. The younger records, Montalbano Jonico and Vallo di Diano, exhibit a distinct retreat of the Mediterranean sclerophyllous plants [START_REF] Combourieu-Nebout | Climate changes in the central Mediterranean and Italian vegetation dynamics since the Pliocene[END_REF]. This retreat may be considered as a consequence of the mid-Pleistocene revolution (at about 1 Ma) during which prevalent 41 kyr glacial-interglacial cycles were replaced by 100 kyr ones [START_REF] Head | Early-Middle Pleistocene transitions: An overview and recommendation for the defining boundary[END_REF]. As emphasized by [START_REF] Leroy | Progress in palynology of the Gelasian-Calabrian Stages in Europe: Ten messages[END_REF] and [START_REF] Tzedakis | Seven ambiguities in the Mediterranean palaeoenvironmental narrative[END_REF], the relative shortness of glacials (although frequently repeated) compared to the length of interglacials before the mid-Pleistocene revolution may have advantaged the Mediterranean sclerophyllous plants in their expansion. Subsequently, during the last 900 ka, this expansion may have been slowed down by the significantly increased length of glacials with respect to interglacials [START_REF] Leroy | Progress in palynology of the Gelasian-Calabrian Stages in Europe: Ten messages[END_REF][START_REF] Tzedakis | Seven ambiguities in the Mediterranean palaeoenvironmental narrative[END_REF]. The Rhône Delta (Camargue) is rich in pollen records showing close and almost continuous climatostratigraphic relationships with the oxygen isotope curve of the GISP2 ice-core (figure 8). Percentages of Mediterranean sclerophyllous plants show episodic maxima in the lower part of the series which are clustering after 5,000 years cal. BP, the highest ones of which (mostly composed of Quercus ilex-type) precede, by more than 2,000 years the onset of human activity dated at 3245 years cal. BP in the area (figure 8) [START_REF] Arnaud-Fassetta | Evidence for an early land use in the Rhône delta (Mediterranean France) as recorded by late Holocene fluvial paleoenvironments (1640-100 B.C.) Geodyn[END_REF]. This is in agreement with the observations in the nearby Languedoc by [START_REF] Jalut | Holocene circum-Mediterranean vegetation changes: Climate forcing and human impact[END_REF] who propose some aridification process since 5,500 years cal. BP. The new Camargue data contribute to the debate on the climatic vs. anthropogenic forcing of the recent spreading of Mediterranean sclerophyllous plants [START_REF] Beaulieu | Vegetation dynamics in northwestern Mediterranean regions: Instability of the Mediterranean bioclimate[END_REF]. A similar contrast in the representation of Mediterranean sclerophyllous plants is obvious in Southern Spain between the early mid-Pleistocene [START_REF] Joannin | Vegetation response to obliquity and precession forcing during the Mid-Pleistocene Transition in Western Mediterranean region (ODP site 976)[END_REF] and the Holocene [START_REF] Combourieu-Nebout | Rapid climatic variability in the west Mediterranean during the last 25 000 years from high resolution pollen data[END_REF]. As in the case of steppes, the development of Mediterranean sclerophyllous plants is probably first due to climatic forcing and then accentuated by anthropogenic pressure. One must note that the last 50 kyrs correspond to high amplitude of obliquity and low amplitude of eccentricity decreased. The thermic gradient was clearly weaker than the modern one. On the basis of the reconstructed values from pollen data, the thermic gradient in Western Europe is estimated to have been around 0.48°C per degree in latitude during the middle Miocene [START_REF] Fauquette | Latitudinal climatic gradients in Western European and Mediterranean regions from the Mid-Miocene (c. 15 Ma) to the Mid-Pliocene (c. 3.5 Ma) as quantified from pollen data[END_REF]. During the Tortonian (11.63 -7.24 Ma), the climate was warm and humid in Northwestern Europe (MAT 4 to 9°C and MAP 100 to 600 mm higher than today) and warm and dry in the South Mediterranean region (MAT 3 to 4°C higher and MAP less than 200 mm higher than today) (figure 9b). The climatic estimates show that the North-South climatic gradient that existed during the Tortonian was similar to that of the present-day, with increasing gradient, in humidity and temperature, over time [START_REF] Fauquette | Latitudinal climatic gradients in Western European and Mediterranean regions from the Mid-Miocene (c. 15 Ma) to the Mid-Pliocene (c. 3.5 Ma) as quantified from pollen data[END_REF]. However, the precipitation seasonality is not quantified through this method. The results of the climatic quantification based on pollen samples covering the middle Miocene period show that mean annual temperatures (MAT) were higher than today at all sites (~2 to 8°C higher) and that mean annual precipitation (MAP) was higher than today in Southern France, Corsica and North Eastern Spain (between 400 mm and 700 mm higher) and almost equivalent to modern values (maximum 200 mm higher) in Southwestern Europe (figure 9a; [START_REF] Fauquette | Latitudinal climatic gradients in Western European and Mediterranean regions from the Mid-Miocene (c. 15 Ma) to the Mid-Pliocene (c. 3.5 Ma) as quantified from pollen data[END_REF]. From North to South, annual temperatures increased but annual precipitation the last spreading of Mediterranean sclerophyllous plants due to climate significantly preceded the onset of human activity.

History of some emblematic plant taxa

This synthesis would not be complete without considering the biogeographical history of some woody taxa. As a complement to the reviews published by [START_REF] Biltekin | Anatolia: A long-time plant refuge area documented Graham A[END_REF] and [START_REF] Magri | Quaternary disappearance of tree taxa from Southern Europe: Timing and trends[END_REF], we pay attention to three taxa, the behaviour of which over time may significantly complete our understanding of the history of peri-Mediterranean vegetation and the onset of the modern ecosystems.

Microtropis fallax Pitard (Celastraceae)

This pollen grain is one of the few to benefit from identification at the species level because its morphology is very specific within the genus Microtropis and itself within the Celastraceae family, as argued by [START_REF] Lobreau-Callen | Présence de pollens de Microtropis fallax (Celastraceae) dans le Pléistocène inférieur de Celleneuve (Hérault)[END_REF]. That fact should not be lost by Bertini & Martinetto (2011: p. 240) in their claim that the correct identification of this taxon may require observation by SEM.

Although we have SEM photographs, their publication is of little value in the identification of pollen of Microtropis fallax because the decisive characters concern the inner structure of the pollen membrane and not its surface ornamentation. The species is rarely but continuously recorded around the entire Mediterranean Sea s.l. (figure 1) from the early Miocene to early Pleistocene inclusive (table 2) (detailed distribution in theses n° 2-4-5-6-7-9-10-13-14-16-17-21-23-25-26-29: table 1). Today, Microtropis fallax is confined to two localities from Vietnam [START_REF] Merrill | The Old Word species of the Celastraceous genus Microtropis Wallich[END_REF] where it is a constituent of the evergreen broad-leaved forest living under warm climate with dry summer (3 months) and very moist autumn, strongly influenced by the nearby sea [START_REF] Vidal | La végétation du Laos, 2 e partie[END_REF]. It can be hypothesized that M. fallax participated with Mediterranean sclerophyllous plants within ecosystems adapted to dry soils during the Miocene and early Pliocene, then disappeared when the temperature fall became too intense. M. fallax is not reported in the European macrofloras that are mainly documenting the temperature and decreasing precipitation, but with higher temperatures. On the basis of the reconstructed MAT, [START_REF] Fauquette | Latitudinal climatic gradients in Western European and Mediterranean regions from the Mid-Miocene (c. 15 Ma) to the Mid-Pliocene (c. 3.5 Ma) as quantified from pollen data[END_REF] showed that the thermic gradient was around 0.6°C per degree in latitude.

During the earliest Pliocene (5.3 -5 Ma), the climatic reconstructions show that the average climate was warm and humid in Europe and the North Mediterranean region (MAT 1 to 4°C and MAP 400 to 700 mm higher than today), and warm and dry in the South Mediterranean region (1 to 5°C warmer and at least as dry as today) (figure 9c; Fauquette et al., 1998a[START_REF] Fauquette | Climate and biomes in the West Mediterranean area during the Pliocene[END_REF][START_REF] Fauquette | Latitudinal climatic gradients in Western European and Mediterranean regions from the Mid-Miocene (c. 15 Ma) to the Mid-Pliocene (c. 3.5 Ma) as quantified from pollen data[END_REF][START_REF] Fauquette | Quantification of the northern Italy Pliocene climate from pollen dataevidence for a very peculiar climate pattern[END_REF]. A North-South climatic gradient existed at the beginning of the Pliocene with, as today, increasing temperatures and decreasing precipitation. The thermic gradient is estimated to have been around 0.6°C per degree in latitude [START_REF] Fauquette | Climate and biomes in the West Mediterranean area during the Pliocene[END_REF][START_REF] Fauquette | Latitudinal climatic gradients in Western European and Mediterranean regions from the Mid-Miocene (c. 15 Ma) to the Mid-Pliocene (c. 3.5 Ma) as quantified from pollen data[END_REF].

Our results thus confirm the existence of a North to South temperature gradient and a South to North precipitation gradient during the Neogene, but it appears that clearly the thermic gradient changed through time. Our results place the transition from the weak thermic gradient of the middle Miocene to the modern-like gradient of the Pliocene during the late Miocene, just before or during the Tortonian. The precipitation gradient was more pronounced during the Neogene than it is today. The transition to the modern gradient seems to have occurred during the lower Pleistocene, at the time of the earliest Northern Hemisphere glacial-interglacial cycles. The climate of these first cycles has been reconstructed based on the Semaforo pollen sequence (lower part of the Crotone series: figures 5-6; [START_REF] Combourieu-Nebout | Vegetation response to upper Pliocene glacial/interglacial cyclicity in the central Mediterranean[END_REF] which covers the period between 2.46 and 2.11 Ma, i.e. nine glacial/interglacial cycles [START_REF] Klotz | Seasonality intensification and long-term winter cooling as a part of the late Pliocene climate development[END_REF]. Our estimates indicate higher temperatures and precipitation than today during interglacials (MAT ~3°C higher, MAP 500 mm higher), but temperatures were equivalent to or lower than today and precipitation equivalent to modern levels during glacials. Moreover, throughout consecutive interglacials, a trend toward a reduction in annual and winter temperatures and toward higher seasonality is observed. During consecutive glacials, a trend toward a reduction in all temperature parameters is evident. Finally, the climatic amplitudes of the interglacial-glacial transitions progressively increased through time [START_REF] Klotz | Seasonality intensification and long-term winter cooling as a part of the late Pliocene climate development[END_REF]. In the Rhône Delta, a distribution has never been successfully explained. According to molecular clock estimates, C. deodara diverged at about 55 Ma, C. atlantica between 20 and 17 Ma while C. libani and C. brevifolia separated between 8 and 5 Ma [START_REF] Qiao | Phylogeny and biogeography of Cedrus (Pinaceae) inferred from sequences of seven paternal chloroplast and maternal mitochondrial DNA regions[END_REF].

A first synthesis of the history of Cedrus was attempted by [START_REF] Pons | L'histoire du genre Cedrus d'après les données paléobotaniques disponibles[END_REF] despite only a limited documentation of macroremains and insufficient information from pollen records. However, the ancient origin (Lower Cretaceous?) of the genus seems to be established as attested by the occurrence of some Cedrus-like pollen grains in Upper Cretaceous deposits from central France [START_REF] Bassil | Investigation of the nature and origin of the geological matrices rich in selenium within the Hydrogeological Experimental Site of Poitiers, France[END_REF]. The Cedrus bisaccate pollen is easily identifiable thanks to the jointed shape of its air-sacs and thickness of its cappa [START_REF] Van Campo-Duplan | Recherches sur la phylogénie des Abiétinées d'après leurs grains de pollen[END_REF] and the long walls of the large alveoli of the air-sacs [START_REF] Sivak | Les caractères de diagnose des grains de pollen à ballonnets[END_REF]. Such an homogenous pollen morphology makes it difficult to identify isolated pollen grains at the species level for which [START_REF] Aytug | Étude des pollens du genre Cèdre (Cedrus Link.)[END_REF] [START_REF] Magri | exhumation and uplift of the Internal Zone of the Rif chain: Insights from low temperature thermochronometry and basin analysis[END_REF] and completed by [START_REF] Magri | Quaternary disappearance of tree taxa from Southern Europe: Timing and trends[END_REF], leading to a reconstruction of its history around the Mediterranean Basin. A few Cedrus pollen grains have been recorded on both sides of the Arctic Ocean, in the New Siberian Islands [START_REF] Suan | Subtropical climate conditions and mangrove growth in Arctic Siberia during the early Eocene[END_REF] and the Mackenzie Delta (Salpin et al., accepted) where it confirms a first presence, observed by [START_REF] Rouse | Palynological zonation of Cretaceous and Early Tertiary rocks of the Bonnet Plume Formation, Northeastern Yukon, Canada[END_REF], during cooler phases surrounding the early Eocene Climatic Optimum, i.e. at 58 -54 Ma and 50 -38 Ma (Suc, unpublished).

These findings reveal a high potential on the American and Eurasian continents for unravelling the history of Cedrus (figure 10).

North America

The Cenozoic history of Cedrus in North America is poorly documented: about ten localities are reported by [START_REF] Thompson | Pliocene environments and climates in the Western United States[END_REF] and Graham (1999), mostly in the Western moister forest ecosystems. Its absence may be explained by its ecological requirements for seasonally dry environments.

Zelkova (Ulmaceae)

The history of Zelkova was reported at the Northeastern Mediterranean scale by [START_REF] Biltekin | Anatolia: A long-time plant refuge area documented Graham A[END_REF]. The recent discovery of the living plant in Sicily (Z. sicula di Pasquale, Garfi & Quézel: di Pasquale et al., 1992;[START_REF] Quézel | Découverte d'un Zelkova en Sicile sud-orientale. Incidences biogéographiques et historiques[END_REF] requires us revisit its pollen records in the Northwestern Mediterranean region. [START_REF] Follieri | Late Pleistocene Zelkova extinction in Central Italy[END_REF] provided evidence of its last record in pollen successions from the Rome area at about 31,000 years BP.

Recently, two offshore cores provided long pollen records, PRGL1-4 in the Gulf of Lions (Suc et al., in progress) and PRAD1-2 near the Gargano Peninsula (thesis n° 12: table 1) (figure 5). In the PRGL1-4 core, Zelkova occurs during each warm phase whatever its intensity, accompanied by Pterocarya, up to the end of the Last Interglacial (ca. 70 ka). They are both absent from all the colder phases since 500 ka, and that shows their extreme frailty during the recent glacial-interglacial cycles. In the PRAD1-2 core, at a latitude closer to Sicily, they are both present during the Last Interglacial and recorded episodically during the Last Glacial and the Holocene up to 6,000 years cal. BP., a little younger age than considered by [START_REF] Magri | Quaternary disappearance of tree taxa from Southern Europe: Timing and trends[END_REF], suggesting its elimination in the Gargano Peninsula was caused by Man. Such recent evidence supports the continued survival of Zelkova up until today in Sicily. [START_REF] Quézel | Découverte d'un Zelkova en Sicile sud-orientale. Incidences biogéographiques et historiques[END_REF] [START_REF] Zhou | Neogene paleoenvironmental changes and their role in plant diversity in Yunnan, South-Western China[END_REF]. In addition, it cannot be excluded that this cedar may have had a larger extent to the West according to the occurrence of some pollen grains close to those of C. deodara up to the early Pliocene in the Northwestern Mediterranean region. Accordingly, a reduction of area similar to that of Cathaya and Tsuga may have affected this species.

Western Asia

Eastern Asia

The history of Cedrus deodara, today restricted to the southern slope of the Himalayas, is better constrained (figure 10).

According to [START_REF] Hsü | Late Cretaceous and Cenozoic vegetation in China, emphasizing their connections with North America[END_REF], Cedrus seems to have been widespread during the Paleogene (from the Sakhalin Island to Inner Mongolia and Eastern China) and Miocene (from the Tibet Plateau to Eastern China). It has also been recorded from the early Miocene of Southern Myanmar (Popescu, unpublished). [START_REF] Hsü | Late Cretaceous and Cenozoic vegetation in China, emphasizing their connections with North America[END_REF] showed the restriction of Cedrus to the Tibet Plateau during the Pliocene and early Pleistocene and discussed its migration to the southern slopes of the Himalayas during the Pliocene. However, Cedrus could have occupied a larger area on both sides of [START_REF] Popescu | Lago Mare episodes around the Messinian-Zanclean boundary in the deep southwestern Mediterranean[END_REF]. A second possibility is migration from the Calabrian and/ or Sicilian mountains [START_REF] Suc | Pérennité d'un climat thermo-xérique en Sicile, avant, pendant, après la crise de salinité messinienne[END_REF][START_REF] Fauquette | How much did climate force the Messinian salinity crisis? Quantified climatic conditions from pollen records in the Mediterranean region[END_REF], despite the substantial distance to cross (figure 10). Contrasting with the hypothesis of [START_REF] Qiao | Phylogeny and biogeography of Cedrus (Pinaceae) inferred from sequences of seven paternal chloroplast and maternal mitochondrial DNA regions[END_REF] and [START_REF] Alba-Sánchez | Paleobiogeografía de Abies spp. y Cedrus atlantica en el Mediterráneo occidental (península ibérica y Marruecos)[END_REF], migration of Cedrus to North Africa was probably impossible via the Alboran domain because it was partly covered by oceanic waters during the paroxysm of the Messinian Salinity Crisis [START_REF] Bache | A two-step process for the reflooding of the Mediterranean after the Messinian Salinity Crisis[END_REF][START_REF] Bache | Messinian evaporite deposition during sea level rise in the Gulf of Lions (Western Mediterranean)[END_REF] probably because of the preexistence of the Gibraltar Strait [START_REF] Capella | Palaeogeographic evolution of the late Miocene Rifian Corridor (Morocco): reconstructions from surface and subsurface data[END_REF]. As a last hypothesis, Cedrus could have already existed, albeit not significantly, in the Rif Mountains (a pollen grain was recorded in the Tortonian sediments of the Irhachâmene section, in Northern Morocco; [START_REF] Achalhi | The late Miocene Mediterranean-Atlantic connections through the North Rifian Corridor: New insights from the Boudinar and Arbaa Taourirt basins (northeastern Rif, Morocco)[END_REF] and would have benefited from the closure of the Rifian corridor at about 7 Ma [START_REF] Capella | Palaeogeographic evolution of the late Miocene Rifian Corridor (Morocco): reconstructions from surface and subsurface data[END_REF] for colonizing the Middle and Tell Atlas mountains (figure 10). In this particular case, movement of Cedrus into North Africa could have occurred prior to the Messinian Salinity Crisis, and would have been assisted by the Rif orogen [START_REF] Capella | Thick-skinned tectonics closing the Rifian Corridor[END_REF]. In the Alboran Sea, there is weak evidence of Cedrus pollen offshore Algeria and Morocco in the latest Pliocene [START_REF] Suc | Distribution latitudinale et étagement des associations végétales au Cénozoïque supérieur dans l'aire ouest-méditerranéenne[END_REF][START_REF] Feddi | Histoire plio-pléistocène des écosystèmes végétaux de Méditerranée sud-occidentale: apport de l'analyse pollinique de deux sondages en mer d'Alboran[END_REF] while it is rarely recorded that probably fragmented the tree populations. Maybe the Middle East cedar resulted from an isolation process of the Anatolian Peninsula forced by intense tectonic extrusion since ca. 10 Ma (figure 10; [START_REF] Barka | The North Anatolian fault zone[END_REF][START_REF] Meulenkamp | Tertiary palaeogeography and tectonostratigraphic evolution of the Northern and Southern peri-Tethys platforms and the intermediate domains of the African-Eurasian convergent plate boundary zone[END_REF][START_REF] Jolivet | Lithospheric-scale geodynamic context of the Messinian salinity crisis[END_REF].

During the late Miocene, propagation of the North Anatolian fault halted, that resulted in relief uplift [START_REF] Armijo | Westward propagation of the North Anatolian fault into the northern Aegean: Timing and kinematics[END_REF]Karaca et al., 2018) et al., 2011). C. atlantica is also indicated by the same authors as present during the late Miocene and early Pliocene. C. deodara would have persisted in the South Caucasus area up to the Last Glaciation [START_REF] Shatilova | The history of the flora and vegetation of Georgia (South Caucasus)[END_REF] and is replaced today by re-introduced C. libani [START_REF] Denk | Vegetational patterns and distribution of relict taxa in humid temperate forests and wetlands of Georgia (Tanscaucasia)[END_REF]. This illustrates how complex the history of Cedrus is in Eurasia due to the co-existence of fossil species and the emergence of the modern ones; the history is arduous to decipher because of the lack of fossil macroremains and difficulty in distinguishing the species using pollen morphology alone.

Europe and North Africa

The history of cedar in Europe is also complex. Cedrus was pointed out in relation to the occurrence of Mediterranean massifs since the Oligocene [START_REF] Fauquette | Quantifying the Eocene to Pleistocene topographic evolution of the southwestern Alps, France and Italy[END_REF], that confirms its ancient presence on the continent [START_REF] Ferguson | On the phytogeography of coniferales in the European Cenozoic[END_REF]. In Southern France (Languedoc), a rich early Pliocene assemblage suggests the existence of a dominant fossil Cedrus species, indicated by a coarser pollen grain (with thick cappa and dense alveolate network in the air-sacs) [START_REF] Suc | La végétation et le climat du Languedoc (sud de la France) au Pliocène moyen d'après la palynologie[END_REF], consistent with the assumption of [START_REF] Pons | Contribution palynologique à l'étude de la flore et de la végétation pliocènes de la région rhodanienne[END_REF]. In addition, several other pollen grains show a morphology close to that of C. atlantica and rare specimens are similar to C. deodara. Progressively, Cedrus disappeared during the Neogene from the higher latitudes to survive

Conclusion

This review shows how much high quality pollen records are needed for reliable past reconstructions of flora, vegetation and climate. In this synthesis, the pollen data show that large number of thermophilous (from megatherm to mesotherm) and hygrophilous taxa successively disappeared from the Mediterranean area throughout the Neogene. However, the great plant biodiversity was not really affected because plant extinctions were rapidly balanced by diversification of new taxa, especially among herbs and shrubs, that maintained the region as an hotspot of plant diversity [START_REF] Médail | Hot-Spots analysis for conservation of plant biodiversity in the Mediterranean Basin[END_REF][START_REF] Médail | Hotspots revisited: Earth's biologically richest and most endangered terrestrial ecoregions[END_REF]. The North Mediterranean plant ecosystems have been deeply modified during the last 23 Ma, evolving from forest conditions to open landscapes: Avicennia mangrove disappeared, Glyptostrobus swamps disappeared later too, Mediterranean sclerophyllous ecosystems replaced subtropical evergreen forests, and lastly Artemisia steppes alternated with mesophilous forests during glacialinterglacial cycles. In contrast, the South Mediterranean plant ecosystems continuously sustained an open structure of vegetation with subdesertic associations where the Avicennia mangrove persisted up to the early Pliocene before invasion by the Artemisia steppe. The Mediterranean sclerophyllous plants, already present in the early Miocene, benefited first from the extinction of thermophilous-hygrophilous elements, then fluctuated in relation with temperature variations. They appear, however, to have been advantaged during some phases of high instability in seasonality (high amplitude of obliquity) and low variability in heat (low amplitude of eccentricity). Before its regional extinction, Microtropis fallax can be regarded as a reliable indicator of primitive Mediterranean sclerophyllous populations. At the scale of the whole Late Cenozoic, plant extinctions appear to have been mostly driven along a North-South latitudinal gradient despite some influence of longitude effects (e.g. diversification of rainfall). This general process cannot hide more complex modes that the detailed study of Quaternary glacials-interglacials allows us to decipher [START_REF] Magri | Quaternary disappearance of tree taxa from Southern Europe: Timing and trends[END_REF]. These include the protective or destructive effects of peculiar geographic situations (e.g. some azonal and irregular strengthening of continental ice during glacials; Tzedakis et al., 2013) or in Southern Spain since the mid-Miocene (thesis n° 17, table 1; [START_REF] Jiménez-Moreno | Miocene to Pliocene vegetation reconstruction and climate estimates in the Iberian Peninsula from pollen data[END_REF]Suc, unpublished). This hypothesis, supported by new data, offers reliable solutions to the questions asked by [START_REF] Magri | exhumation and uplift of the Internal Zone of the Rif chain: Insights from low temperature thermochronometry and basin analysis[END_REF] and [START_REF] Magri | Quaternary disappearance of tree taxa from Southern Europe: Timing and trends[END_REF]. Especially, it provides robust information because most of the pollen data come from prodeltaic sediments forced by river supply and undisturbed by long-distance wind transport, suspected to have biased some late Quaternary European lacustrine records [START_REF] Magri | Late Quaternary western Mediterranean pollen records and African winds[END_REF][START_REF] Magri | exhumation and uplift of the Internal Zone of the Rif chain: Insights from low temperature thermochronometry and basin analysis[END_REF][START_REF] Magri | Quaternary disappearance of tree taxa from Southern Europe: Timing and trends[END_REF]. Otherwise, the persistence of Cedrus in Southern Spain during the late Pleistocene is still debated (Postigo-Mijarra et al., 2010;[START_REF] Joannin | Vegetation response to obliquity and precession forcing during the Mid-Pleistocene Transition in Western Mediterranean region (ODP site 976)[END_REF][START_REF] Alba-Sánchez | Paleobiogeografía de Abies spp. y Cedrus atlantica en el Mediterráneo occidental (península ibérica y Marruecos)[END_REF]. Once established in Morocco, Cedrus was helped by the uplifting Rif Mountains that peaked during the Pliocene [START_REF] Romagny | Cryptic or mystic? Glacial tree refugia in northern Europe[END_REF] and led, at mid to high altitude, to wetter and cooler climatic conditions more suitable for this conifer. Cedrus atlantica was probably saved from extinction by its migration from Europe to North Africa which offered new habitats protecting it from the forthcoming glacials (figure 10), especially from those of the late Pleistocene which decimated the European cedar populations and made the North African ones highly unstable [START_REF] Cheddadi | Putative glacial refugia of Cedrus atlantica deduced from Quaternary pollen records and modern genetic diversity[END_REF]. Cedrus almost disappeared during medieval times from most of the pollen records, indicating its regression to its present-day stands on mountain crests in the Rif and Atlas [START_REF] Muller | Vegetation history of the western Rif mountains (NW Morocco): Origin, late-Holocene dynamics and human impact[END_REF].

To summarize, it appears that the greatly disconnected geographic distribution of Cedrus species mainly results from the progressive but unavoidable restriction of their habitat area caused by decreasing temperatures in the Northern Hemisphere (figure 10). However, it seems that the three surviving species may have been saved by strong geodynamic events: uplift of the Himalayas (including the Tibet Plateau) for C. deodara, extrusion of the Anatolian Peninsula for C. libani, and brief desiccation of the Mediterranean Sea and maybe Rif orogen for C. atlantica (figure 10). Maybe the geodynamical passive the North American craton did not provide sufficient mountain habitats and boost enough cedar populations there to allow its survival during the Northern Hemisphere glaciations.

progressively acquired ability of some plants or ecosystems to survive in hard conditions (Svenning et al., 2015). Climatic interpretation of pollen records and their quantification in terms of palaeoclimate parameters emphasize a latitudinal contrast in temperature and in humidity/ dryness, the thermic latitudinal gradient being characterized by a significant increase in the late Miocene towards its modern value.

Characterized by elevated temperatures and some seasonality in dryness from 23 to 3.37 Ma, climate evolved with cooler winters and drought concentrated in summers when earliest glacials occurred at 2.6 Ma with generalized dryness and colder conditions alternating with moister and warmer conditions during interglacials. The present-day refuges of some mesophilous taxa, such as the "climate relicts" Zelkova and Pterocarya, may be considered as representative of this highly contrasted history, both from a biogeographical and climatic point of view. The desiccation phase of the Messinian Salinity Crisis did not severely impact the region but forced the subdesertic elements to momentarily migrate northward [START_REF] Fauquette | How much did climate force the Messinian salinity crisis? Quantified climatic conditions from pollen records in the Mediterranean region[END_REF][START_REF] Popescu | Earliest Zanclean age for the Colombacci and uppermost Di Tetto formations of the "latest Messinian" northern Apennines: New palaeoenvironmental data from the Maccarone section (Marche Province, Italy)[END_REF] and offered cedar the opportunity to reach North Africa. The present-day patchy distribution of Cedrus seems to have been influenced by geodynamic events, which offered opportunities to persist, despite repeated coolings.

Figure 1 -

 1 Figure 1 -Geographic location of the studied Late Cenozoic pollen floras in the Mediterranean region considered in this paper. Larger dots correspond to long pollen records. The present-day limits of the Mediterranean climate are from Quézel & Médail (2003). The maximum expansion of the Mediterranean Sea (early Miocene) is from Meulenkamp & Sissingh (2003). All the maps are elaborated using GeoMapApp from Ryan et al. (2009).

Figure 2 -

 2 Figure 2 -Location map of selected significant pollen floras from the Northwestern Mediterranean region.From Northeastern Spain to Southeastern France: 1, Vilobi del Penedès; 2, Sant Pau d'Ordal; 3, La Rierussa; 4, Papiol; 5, Torrente del Terme; 6, Garraf 1; 7, Ciurana; 8, Can Cateura; 9, Banyoles; 10, Can Vilella; 11, Sampsor; 12, Sanavastre; 13, Vivès; 14, Le Boulou; 15, Leucate SC1; 16, Portel -Sigean; 17, Narbonne: V. Hugo College; 18, Lespignan; 19, Montredon; 20, Montady; 21, Cessenon; 22, Bernasso; 23, Cap d'Agde 1; 24, Issanka; 25, Poussan; 26, Montbazin; 27, Caunelle; 28, Montpellier; 29, Pichegu; 30, Pierrefeu 1; 31, Fournès; 32, Vacquières; 33, Mirabel; 34, Autan 1; 35, Estagel -Bayanne; 36, Les Tamaris; 37, Carry-le-Rouet; 38, Aix-en-Provence -Venelles; 39,Vaugines; 40, La Motte-d'Aigues; 41, Fabrègues; 42, Oraison (Flour); 43, Villeneuve; 44, Les Mées (Périgoite); 45, Les Mées 1; 46, Le Rochassas; 47, Châteauredon; 48, Escaravatier; 49, Vence; 50, Le Gourg; 51, Carros; 52, Saint-Paul-de-Vence; 53, Saint-Isidore; 54, Saint-Martin-du-Var.

Figure 3 -

 3 Figure 3 -Synthetic pollen diagrams distributed from West to East with respect to chronology and climatostratigraphy correlated with the reference oxygen isotope records. MIS, Marine isotope stages. Site numbers in brackets refer to Figure 2.

Figure 4 -

 4 Figure 4 -Heterogeneity of the Mediterranean region with regard to the evolution of some plantecosystems.

Figure

  Figure 5 -Location map of pollen sites considered for reconstructing the history of the Mediterranean sclerophyllous plants since 3.6 Ma and the two sites showing last occurrences of Zelkova. 1, Garraf 1; 2, MD99-2348 and PRGL1-4; 3, 92K19; 4, Saint-Ferréol; 5, Piton; 6, Fangassier; 7, BF6; 8, 92K04; 9, 92K08; 10, Camerota; 11, Vallo di Diano; 12, Montalbano Jonico; 13, Crotone; 14, PRAD1-2.

Figure 6 -

 6 Figure 6 -History of the Mediterranean sclerophyllous plants between 3.6 and 0.9 Ma according to pollen records from four localities: Garraf 1 (Cravatte & Suc, 1981), Crotone (Suc et al., 2010), Camerota (Brenac, 1984), Montalbano Jonico (Joannin et al., 2008). The curve of percentages of Mediterranean sclerophyllous plants (Ceratonia, Nerium, Myrtaceae, Olea, Quercus ilex-type, Rhamnaceae, Pistacia, Phillyrea, Cistus, Phlomis cf. fruticosa, Rhus cf. cotinus), based on the total pollen sum (Pinus excluded), is plotted with the curve of the ratio "thermophilous/steppe elements", a reliable indicator of climatic changes. Chronostratigraphic relationships with the reference oxygen isotope curve are indicated by dotted lines according to already established cyclostratigraphic correlations (Suc & Popescu, 2005; Joannin et al., 2008; Suc et al., 2010). Grey bands display isolated peaks or clusters of peaks of Mediterranean sclerophyllous plants exceeding 3% of the pollen sum and correlate them with the other proxies. The amplitude curves of eccentricity and obliquity are constructed thanks to a mathematical calculation of their envelope, respectively.

Figure 7 -

 7 Figure 7 -History of the Mediterranean sclerophyllous plants between ca. 600 and 0.013 ka according to pollen records from three localities: Vallo di Diano (Russo Ermolli, 1994; Russo Ermolli & Cheddadi, 1997), PRGL1-4 (Suc et al., in progress), MD99-2348 (Beaudouin et al., 2005a). Same explanations as for Figure 6.

Figure 8 -

 8 Figure 8 -History of the Mediterranean sclerophyllous plants since ca. 11,2000 years cal. BP according to pollen records from six localities: 92K19 (Beaudouin et al., 2005a); 92K08 and 92K04 (thesis n° 1), Piton (thesis n° 3); Saint-Ferréol (thesis n° 11), BF6 (thesis n° 27) -thesis references are in Table1. Same explanations as for Figure6without the eccentricity and obliquity amplitudes not illustrated here.

Figure 9 -

 9 Figure 9 -Climatic reconstructions from pollen data (climatic interval and most likely value) in Western Europe and Mediterranean region showing the gradients of temperature (mean annual temperature in °C) and precipitation (mean annual precipitation in mm) for (a) the middle Miocene (Langhian/Serravallian, ~14 -15 Ma), (b) the late Miocene (Tortonian, ~10 Ma), (c) the early Pliocene (Zanclean, ~5.3 -5 Ma). Modern values are indicated by a cross to show the differences between modern and past latitudinal gradients (modified from Fauquette et al., 2007).

Biltekin

  et al. (2015) assume that the early to mid-Miocene cedar from Anatolia refers to the C. libani -C. brevifolia lineage while the late Miocene -early Pliocene cedar is referable to C. libani. They show that Cedrus continuously inhabited the Anatolian reliefs up until the development of Artemisia steppes USA along the Rocky Mountains, the most important of them concerings the late Miocene (Leopold & Denton, 1987) and the youngest the mid-Pliocene (Graham, 1999). The conditions and timing of the extinction of Cedrus from North America are enigmatic. Is there some relationship with the North-South alignment of the Rocky Mountains? Was the competition too hard with Tsuga still alive on the two sides of the continent?

Figure 10 -

 10 Figure 10 -North planisphere showing (1) the present-day distribution (in black) of the three living species of Cedrus, (2) the highest latitudinal places where the genus is recorded from early Eocene deposits, (3) the climatic forcing causing its weakening and surface regression, and (4) the intense geodynamic events which could be at the origin of the present refuges.

table 2

 2

	):

Table 1 -Listing of the 29 pollen analytic theses that contributed to establish the Mediterranean flora during the Late Cenozoic. Authors of Master theses are underlined, those of PhD theses are in normal characters, those of State theses are in bold characters.

 1

	Thesis N°N ame	Year Title

Les premiers cycles glaciaires-interglaciaires en région méditerranéenne d'après l'analyse palynologique de la série plio-pléistocène de Crotone (Italie méridionale)

Table 2 -Listing of taxa (at the family, genus and sometimes species level) identified at the Mediterranean scale according to pollen grains from the Late Cenozoic deposits, distributed according to the main chronostratigraphic subdivisions. Taxa identified for the first time in the Mediterranean Late Cenozoic are underlined in grey.

 2

	Family	Genus	Species		Miocene		Pliocene		Quaternary
				early	middle	late	early	late	early	middle	late	Holocene
	Megatherm plants:
	Acanthaceae			+	+	+	+	+	+
		Avicennia		+	+	+	+		+
		Blepharis							+
	Bombacaceae	Bombax		+	+	+	+		+
	Buxaceae	Buxus	bahamensis-type	+	+	+	+
	Cucurbitaceae						+
	Euphorbiaceae			+	+	+	+	+
		Alchornea		+	+	+	+	+
		Amanoa				+	+
		Claoxylon-type		+	+
		Croton		+	+	+	+	+	+
		Jatropha		+	+
		Phyllanthus-type			+	+
	Leguminosae Caesalpinioideae			+	+	+
		Sindora			+	+	+
	Mimosoideae			+	+	+	+
		Acacia		+	+
		Prosopis	cf. farcta	+	+	+	+	+	+
	Hamamelidaceae	Altinghia				+
		Fothergilla		+	+	+	+
	Icacinaceae			+	+	+	+
		Mappianthus		+	+
	Malpighiaceae			+	+	+			+
		Malpighia		+	+
	Malvaceae	Grewia -Corchorus		+	+	+
	Melastomataceae			+	+	+
	Meliaceae			+	+	+	+
	Passifloraceae			+	+	+	+	+
	Rubiaceae			+	+	+
		Canthium-type				+		+
	Rutaceae			+	+	+	+
	Simaroubaceae	(Pentapollenites: fossil genus)		+	+	+
		Picrasma		+	+
	Mega-mesotherm plants:
	Asparagaceae				+	+	+
		Cordyline		+	+
		cf. Dracaena					+
		Nolina				+	+		+
	Alangiaceae	Alangium			+		+
	Anacardiaceae			+	+	+	+	+	+	+

From Northeastern Spain to Southeastern France: 1, Vilobi del Penedès; 2, Sant Pau d'Ordal; 3, La Rierussa; 4, Papiol; 5, Torrente del Terme; 6, Garraf 1; 7, Ciurana; 8, Can Cateura; 9, Banyoles; 10, Can Vilella; 11, Sampsor; 12, Sanavastre; 13, Vivès; 14, Le Boulou; 15, Leucate SC1; 16, Portel -Sigean; 17, Narbonne: V. Hugo College; 18, Lespignan; 19, Montredon; 20, Montady; 21, Cessenon; 22, Bernasso; 23, Cap d'Agde 1; 24, Issanka; 25, Poussan; 26, Montbazin; 27, Caunelle; 28, Montpellier; 29, Pichegu; 30, Pierrefeu 1; 31, Fournès; 32, Vacquières; 33, Mirabel; 34, Autan 1; 35, Estagel -Bayanne; 36, Les Tamaris; 37, Carry-le-Rouet; 38, Aix-en-Provence -Venelles; 39,Vaugines; 40, La Motte-d'Aigues; 41, Fabrègues; 42, Oraison (Flour); 43, Villeneuve; 44, Les Mées (Périgoite); 45, Les Mées 1; 46, Le Rochassas; 47, Châteauredon; 48, Escaravatier; 49, Vence; 50, Le Gourg; 51, Carros; 52, Saint-Paul-de-Vence; 53, Saint-Isidore; 54, Saint-Martin-du-Var.

  , however, indicated some distinctive characters: slightly thicker cappa in C. deodara, thinner cappa in C. atlantica, and with lateral crests in C. libani. In addition, the longest walls of the large alveoli of the airsacs can be observed in C. deodara.

	Now we have at disposal enough high-quality
	pollen data to reconstruct a reliable history
	of Cedrus for the Late Cenozoic, particularly
	for the Mediterranean region s.l. A thorough
	review of Quaternary Cedrus records (pollen
	grains and macroremains) in Southern
	Europe was provided by

  were surprised by the modern occurrence of Zelkova in Sicily. Surprising too is the present-day absence of living remnants of Pterocarya in the Central Mediterranean region.

	Cedrus (Pinaceae)
	Three species are now accepted within the
	Cedrus genus: C. deodara (Roxb. Ex D.
	Don) G. Don, C. atlantica (Endl.) Manetti ex
	Carrière, and C. libani A. Rih. (The Plant List,
	2013). These species live today in disjunct
	distribution areas (Quézel, 1998): C. deodara
	in the Himalayas realm, from Afghanistan

to Nepal; C. atlantica in Northern Africa (Morocco and Algeria); C. libani in the Eastern Mediterranean region (Turkey to Lebanon) including C. brevifolia (Hook. f.) Henry, a taxon restricted to Cyprus (figure 10). Such the Himalayas before the uplift of the Tibet Plateau. Uplift started in the mid-Eocene, with repeated strong phases, mainly in the early Oligocene and since the mid-Miocene (15 Ma; Wang et al., 2012), during which time Cedrus was eliminated from the northern part of the mountain chain. Cedrus persisted in Southwestern China up until the late Pliocene from where it was probably eliminated by the onset of dry winters and early springs

herbariums (Montpellier, Lyon, Geneva and Paris) to provide flowers for reference pollen. Two anonymous reviewers are particularly thanked for their constructive comments, which significantly improved the manuscript. Dr Keith Richards is warmly acknowledged for editing the English text. This paper is the ISEM contribution n°2018-109 SUD.

Ackowledgements

We express a grateful tribute to Pierre Quézel who still supported our researches with enthusiasm and significantly contributed to them by providing so much information and advices. Some data were provided by E. Russo Ermolli, and information by A. Graham and R.S. Thompson. Since the 1970's, our investigations have been supported and funded by many national (IFB, CNRS, ANR, MISTRALS, Actions Marges, PhD theses) and international (ESF, PROMESS, PhD theses) programs in addition to academic (Universities of Montpellier II and Lyon I) and private support (TOTAL). Many botanical identifications of pollen grains were possible thanks to (1) the use of the Montpellier modern pollen collection (ISEM) and to the continuous availability of its ex-manager J. Chambon, and (2) the willingness of several