Igor V Bartish

Salomé Bonnefoi

Abdelkader Aïnouche

Helge Bruelheide

Mark Bartish

Andreas Prinzing
email: andreas.prinzing@univ-rennes1.fr

Fewer chromosomes, more co-occurring species within plant lineages -a likely effect of local survival and colonization

Keywords: chromosome number, ecological niche, genome size, life-history traits, polyploidy, species richness of lineages chromosome number, coexistence, ecological genetics and ecogenomics, genome size, life-history traits, locally species-rich families, polyploidy, species communities, species richness of lineages

Plant lineages differ markedly in species richness globally, regionally, and locally.

Differences in whole-genome characteristics (WGCs) such as monoploid chromosome number, genome size, and ploidy level may explain differences in global species richness through speciation or global extinction. However, it is unknown whether WGCs drive species richness within lineages also in a recent, postglacial regional flora, or in local plant communities, through local extinction or colonization and regional species turn-over.

Methods

We tested for relationships between WGCs and richness of angiosperm families across the Netherlands/Germany/Czechia as a region, and within 193449 local vegetation plots.

Key results

Families that are species-rich across the region have lower ploidy levels and small monoploid chromosomes numbers or both (interaction terms), but the relationships disappear after accounting for continental and local richness of families. Families that are species-rich within occupied localities have small numbers of polyploidy and monoploid chromosome numbers or both, independent of their own regional richness and the local richness of all other locally cooccurring species in the plots. Relationships between WGCs and family species-richness persisted after accounting for niche characteristics and life histories.

Conclusions

Families that have few chromosomes, either monoploid or holoploid, succeed in maintaining many species in local communities and across a continent and, as indirect consequence of both, across a region. We suggest evolutionary mechanisms how small chromosome numbers and ploidy levels might decrease rates of local extinction and increase rates of colonization.

The genome of a macroevolutionary lineage may ultimately control whether its species can ecologically coexist.

INTRODUCTION

Plant lineages differ dramatically in species richness and at global geographic scale such differences have often been explained by whole-genome characteristics (WGC). Specifically, some plant lineages are rich in species and others are poor, such as the emblematic contrast between a single extant species of Amborellaceae and more than 250 000 species of its sister clade, the remaining Angiosperms [START_REF] Chase | Phylogenetics of seed plants: an analysis of nucleotide sequences from the plastid gene rbcL[END_REF]Christenhusz and Byng 2016). The richness of a lineage across the globe obviously increases with rates of speciation and decreases with rates of extinction. Lineages differ among others in WGC with respect to ploidy level, monoploid chromosome number and monoploid genome size [START_REF] Soltis | Phylogeny and evolution of Angiosperms[END_REF]Soltis et al., 2014;[START_REF] Bromham | Exploring the relationships between mutation rates, life history, genome size, environment, and species richness in flowering plants[END_REF], and WGC of lineages have often been used to explain rates of speciation, global extinction and richness of lineages [START_REF] Wood | The frequency of polyploid speciation in vascular plants[END_REF][START_REF] Kraaijveld | Genome size and species diversification[END_REF][START_REF] Mayrose | Recently formed polyploid plants diversify at lower rates[END_REF]Soltis et al., 2014;[START_REF] Puttick | Size is not everything: rates of genome size evolution, not C-value, correlate with speciation in angiosperms[END_REF]. For genome size and numbers of chromosomes results were partly inconclusive [START_REF] Fawcett | Significance and biological consequences of polyploidization in land plants[END_REF][START_REF] Greilhuber | Genome Size and the Phenotype[END_REF][START_REF] Husband | The incidence of polyploidy in natural plant populations: major patterns and evolutionary processes[END_REF] for reviews; [START_REF] Tank | Nested radiations and the pulse of angiosperm diversification: increased diversification rates often follow whole genome duplications[END_REF], and see Kapralov and Filatov, 2011 studying archipelagos). In contrast, for ploidy level results often indicate that high ploidy fosters speciation and diversification [START_REF] Parisod | Impact of transposable elements on the organization and function of allopolyploid genomes[END_REF][START_REF] Jiao | Ancestral polyploidy in seed plants and angiosperms[END_REF]Vannestre et al., 2014;Soltis et al., 2014;[START_REF] Wendel | The wondrous cycles of polyploidy in plants[END_REF][START_REF] Van De Peer | The fowering world: a tale of duplications[END_REF], 2017, 2021;Nieto Feliner et al., 2020;Wu et al., 2020), and possibly reduced extinction rates during deep past mass extinctions [START_REF] Bottini | Relationship among genome size, environmental conditions and geographical distribution in natural population of NW Patagonian species of Berberis[END_REF][START_REF] Fawcett | Plants with double genomes might have had a better chance to survive the Cretaceous-Tertiary extinction event[END_REF][START_REF] Fawcett | Significance and biological consequences of polyploidization in land plants[END_REF][START_REF] Van De Peer | The evolutionary significance of polyploidy[END_REF], but see Soltis et al., 2014;Nieto Feliner et al., 2020;[START_REF] Van De Peer | Polyploidy: an evolutionary and ecological force in stressful times[END_REF].

15372197, ja, Downloaded from https://bsapubs.onlinelibrary.wiley.com/doi/10.1002/ajb2.16139 by Université De Rennes 1 BU Campus Beaulieu -Bât. 40, Wiley Online Library on [10/02/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Plant linages differ in species richness also regionally and locally, but we do not know whether this depends on WGC. Globally species-rich lineages may be species-poor within several regions (like Moraceae in temperate regions) or globally relatively poor lineages may be regionally rich (like Cycadaceae in SE-Asia). Finally, within a given region some lineages may be species-rich but be represented at any occupied locality by only a single species, or inversely, regionally species-poor lineages succeed in maintaining multiple coexisting species in any locality occupied, a phenomenon only relatively recently recognized (Prinzing et al. Accepted Article 2016, [START_REF] Večeřa | Mapping species richness of plant families in European vegetation[END_REF]. In young regional floras, such as those resulting from postglacial recolonization, speciation will be of comparatively little importance for explaining why some lineages are more species-rich than others [START_REF] Kadereit | Quaternary diversification in European alpine plants: pattern and process[END_REF][START_REF] Willis | The role of Quaternary environmental change in plant macroevolution: the exception or the rule? -Philosophical Transactions of the Royal Society of London B[END_REF][START_REF] Kadereit | The role of in situ species diversification for the evolution of high vascular plant species diversity in the European Alps -A review and interpretation of Accepted Article phylogenetic studies of the endemic flora of the Alps. -Perspectives in Plant Ecology[END_REF], but see [START_REF] Abbott | History and evolution of the arctic flora: in the footsteps of Eric Hulten[END_REF][START_REF] Smyčka | Tempo and drivers of plant diversification in the European mountain system[END_REF]. Moreover, speciation will be of practically no importance for explaining why in some lineages more species locally co-occur than in others. In contrast, local and regional richness of lineages will be driven by the rate of local extinction, local colonization and turn-over of species compositions between localities. As we will show below, each of these drivers may in theory strongly depend on WGC. But we do not know whether WGC explains richness of lineages within young regions and within localities occupied.

Local diversity depends on local extinction and local colonization, and WGC might drive both. Specifically, for each site occupied by a given lineage the richness of species that can co-occur will increase with a decrease in local extinction rate and an increase in local colonization rate. Extinction is low in species that can maintain even small populations and can persist under local stress or disturbance, or enemy pressure. Colonization rates are high in species producing many descendants of high dispersal capacities. Each of these characteristics may be driven by WGC. First, polyploidization might reduce the risk of local extinctions given the high survival of polyploids after environmental disturbance [START_REF] Te Beest | The more the better? The role of polyploidy in facilitating plant invasions[END_REF][START_REF] Van De Peer | The evolutionary significance of polyploidy[END_REF], 2021). However, polyploidization might also increase the risk of local extinction as it accelerates the rate of genetic and genomic mutations due to transposable elements [START_REF] Hedges | From the margins of the genome: mobile elements shape primate evolution[END_REF][START_REF] Pennisi | Jumping genes into the evolutionary limelight[END_REF]Šímová and Herben, 2012), and most of these mutations will be deleterious [START_REF] Krasileva | Uncovering hidden variation in polyploid wheat[END_REF]. Moreover, the genomic shock following whole-genome merger and doubling (i.e. allopolyploidization) may temporarily trigger disadvantageous and detrimental effects in the early stages of the polyploids formation [START_REF] Comai | The advantages and disadvantages of being polyploid[END_REF][START_REF] Mayrose | Recently formed polyploid plants diversify at lower rates[END_REF][START_REF] Douglas | Hybrid origins and the earliest stages of diploidization in the highly successful recent polyploid Capsella bursa-pastoris[END_REF]and refs above). Also, polyploidization increase cell size, potentially slowing down life history [START_REF] Comai | Do the different parental 'heteronomes' cause genomic shock in newly formed allopolyploids?[END_REF] and increasing the risk of not surviving until maturity. This increase in cell size in polyploids

Accepted Article

Regional richness increases with local richness and with the turn-over of species among localities, and WGC might also drive this turn-over. For a given region, the richness of a lineage will increase with its local richness and with the turn-over of species between localities. This species turn-over will be large if different species within a lineage are adapted to different environments. Such a capacity to develop adaptations to different environments may depend on WGC. First, polyploids frequently differ markedly from their diploid progenitors and exhibit novel morphological, physiological and life-history traits, which are often associated with increased vigour and ability to successfully adapt to novel ecological conditions [START_REF] Schierenbeck | The role of evolutionary genetics in studies of plant invasion[END_REF][START_REF] Fawcett | Significance and biological consequences of polyploidization in land plants[END_REF][START_REF] Mounger | Epigenetics and the success of invasive plants[END_REF][START_REF] Lopez-Jurado | Polyploidy promotes divergent evolution across the leaf economics spectrum and plant edaphic niche in the Dianthus broteri complex[END_REF] for review), likely facilitating the differentiation of species among environments within a region. In contrast, polyploidization may render natural selection less efficient because any given allele of a gene might be masked by multiple other copies might ultimately reduce the number of diaspores produced per year, and thereby, reduce the rate at which localities are colonized. Second, a large monoploid number of chromosomes might increase the risk of local extinction by increasing the risk of chromosome mutations during mitosis [START_REF] Mayr | Animal Species and Evolution[END_REF]. Finally, a large monoploid genome size (quantified as 1Cxvalue) might also increase the risk of local extinctions by reducing photosynthetic rate [START_REF] Knight | The large genome constraint hypothesis: evolution, ecology and phenotype[END_REF][START_REF] Simonin | Genome downsizing, physiological novelty, and the global dominance of flowering plants[END_REF] and creating a saturation DNA "surplus", potentially constraining the evolution of phenotypes [START_REF] Knight | The large genome constraint hypothesis: evolution, ecology and phenotype[END_REF][START_REF] Greilhuber | The origin, evolution and proposed stabili be nuclear DNA contents[END_REF][START_REF] Faizullah | Exploring environmental selection on genome size in angiosperms[END_REF] for reviews on effects of genome size). Large monoploid genome size combined with high ploidy gives a heavy total holoploid genome, potentially increasing the number of lethal alleles in small populations (LaBar and Adami, 2020), and thereby, the risk of extinction [START_REF] Vinogradov | Selfish DNA is maladaptive: evidence from the plant Red List[END_REF][START_REF] Organ | Origin of avian genome size and structure in non-avian dinosaurs[END_REF][START_REF] Kang | Adaptive and nonadaptive genome size evolution in Karst endemic flora of China[END_REF][START_REF] Souza | Do tropical plants have smaller genomes? Correlation between genome size and climatic variables in the Caesalpinia Group (Caesalpinioideae, Leguminosae). -Perspectives in Plant Ecology[END_REF]but see Qiu et al., 2019), and consequently, again potentially increasing the rate of local extinctions and thereby possibly the local richness of lineages. Overall, we hypothesize that large monoploid chromosome number or genome size or their combination reduce local species richness of lineages, and that polyploidy either increases or decreases local richness.

Accepted Article

Testing for statistical effects of WGC on local and regional species richness of plant linages within a region requires exceptionally rich information across many species in many lineages.

It requires information on the richness of these lineages across the entire region and for each lineage across many localities occupied by this lineage. Such testing also requires information on covarying richness of the same lineages across the continental species pool. The continental species pool is likely strongly influenced by speciation, possibly resulting in a pseudocorrelation between of WGC with regional richneess via the effect of WGC on continental species richness. Testing such statistical effects of WGC on local and regional species richness further requires information on covarying richness of other lineages in the same localities as some lineages might be locally rich simply because they occupy sites that harbour many species in general of all lineages. Finally, such testing requires information on [START_REF] Stebbins | Chromosomal Evolution in Higher Plants[END_REF][START_REF] Mayrose | Recently formed polyploid plants diversify at lower rates[END_REF]Soltis et al., 2014), thereby possibly preventing adaptations of different species to different environments within a region. Second, a large monoploid chromosome number might facilitate the adaptation of species to different environments within a region: large monoploid chromosomes number decrease coupling of genes on the same chromosome and increase genome-wide recombination rate, in particular when combined with a low genome size (Mayr 1963, Trickett and[START_REF] Trickett | Recombination suppressors and the evolution of new species[END_REF]. Finally, a small monoploid genome size combined with low ploidy level might increase the capacity to establish new populations given the comparatively higher invasion success of species with such small holoploid genome size (Grotkop et al., 2004;[START_REF] Pandit | The contrasting effects of genome size, chromosome number and ploidy level on plant invasiveness: a global analysis[END_REF], In addition, small genomes might evolve faster than large ones after a genome duplication [START_REF] Levin | Rates of evolution in seed plants: Net increase in diversity of chromosome numbers and species numbers through time[END_REF]. Again, these processes might facilitate adaptation of different species within lineages to different environments, thereby increasing beta diversity across environments within region and regional species richness of lineages. Overall, we hypothesize that regional species richness of lineages depends on WGCs: it increases with monoploid chromosome number, decreases with monoploid or polyploid genome size and might either increase or decrease with ploidy level.

Accepted Article

niche characteristics and life history characters that might mediate the relationships between WGC and species richness of lineages, as indicated above, involving life span [START_REF] Grotkopp | Evolution of genome size in pines (Pinus) and its life-history correlates: Supertree analyses[END_REF][START_REF] Beaulieu | On the Tempo of Genome Size Evolution in Angiosperms[END_REF], life form, stress and disturbance tolerance [START_REF] Hedges | From the margins of the genome: mobile elements shape primate evolution[END_REF][START_REF] Pennisi | Jumping genes into the evolutionary limelight[END_REF]Šímová and Herben, 2012) and extreme ecological distributions (e.g., [START_REF] Grime | Variation in genome size-an ecological interpretation[END_REF][START_REF] Knight | The large genome constraint hypothesis: evolution, ecology and phenotype[END_REF][START_REF] Beaulieu | Genome size evolution to leaf strategy and metabolic rates revisited[END_REF][START_REF] Organ | Origin of avian genome size and structure in non-avian dinosaurs[END_REF][START_REF] Fawcett | Significance and biological consequences of polyploidization in land plants[END_REF][START_REF] Greilhuber | Genome Size and the Phenotype[END_REF]; for reviews). For instance, species with a large (holoploid) C-value or chromosome number have been reported to be restricted to temperate and humid regions [START_REF] Grime | Variation in genome size-an ecological interpretation[END_REF][START_REF] Jacob | The considerable genome size variation of Hordeum species is linked to phylogeny, life form, ecology and speciation rates[END_REF]and references herein), and threatened plant and animal species have been reported to have high C-values [START_REF] Vinogradov | Selfish DNA is maladaptive: evidence from the plant Red List[END_REF][START_REF] Organ | Origin of avian genome size and structure in non-avian dinosaurs[END_REF][START_REF] Kang | Adaptive and nonadaptive genome size evolution in Karst endemic flora of China[END_REF][START_REF] Souza | Do tropical plants have smaller genomes? Correlation between genome size and climatic variables in the Caesalpinia Group (Caesalpinioideae, Leguminosae). -Perspectives in Plant Ecology[END_REF]but see Qiu et al., 2019). Finally, polyploidization has been reported to facilitate naturalization and invasion of introduced species [START_REF] Pandit | Ploidy influences rarity and invasiveness in plants[END_REF][START_REF] Te Beest | The more the better? The role of polyploidy in facilitating plant invasions[END_REF][START_REF] Moura | Polyploidy and high environmental tolerance increase the invasive success of plants[END_REF], and niche expansion in space and time [START_REF] Hegarty | Genomic clues to the evolutionary success of polyploid plants[END_REF][START_REF] Veselý | Genome size and DNA base composition of geophytes: the mirror of phenology and ecology?[END_REF][START_REF] Peruzzi | x" is not a bias, but a number with real biological significance[END_REF].

Here we use exceptionally rich data from Western Central-Europe to test the above hypotheses on statistical effects of WGC on the numbers of species that lineages can maintain regionally and locally. We profit from extensive databases from Czech Republic, Germany, and The Netherlands, on WGC, life histories, niche positions, as well as the local species composition across hundreds of thousands of local plots (e.g. [START_REF] Ellenberg | Indicator values of Central-European plants[END_REF][START_REF] Klotz | BIOLFLOR: Eine Datenbank mit biologischökologischen Merkmalen zur Flora von Deutschland[END_REF][START_REF] Jandt | German Vegetation Reference Database (GVRD)[END_REF]. The family level is a particularly appropriate level to capture the variation of genome characteristics [START_REF] Soltis | Phylogeny and evolution of Angiosperms[END_REF] and largely avoids difficulties due to insufficient resolution or reticulate evolution at finer taxonomic levels (Soltis et al., 2014). We hence used these databases to characterize families by the average ploidy level, monoploid C-value (i.e., 1Cx), and monoploid chromosome number of their species. We accounted for randomly expected relationships between species numbers and genomic characters: largest families may approach overall averages for any traits, including genomic ones. For this we calculated standardized effect sizes of WGCs. Our main aim was to use these standardized WGCs to test whether the number of species a family maintains within

Accepted Article

a region and its localities increases or decreases with ploidy level, monoploid C-value, and monoploid chromosome number. We statistically accounted for phylogenetic nonindependence among families. We supplemented our main tests by a set of relevant secondary tests. In these tests we accounted for the possibility that richness patterns at a finer scale might just reflect sampling from broader-scale patterns, or broad-scale pattern might emerge as the sum of fine-scale patterns, without any relationships genuine to the intermediate scale. We finally explored whether the effect of WGCs on species richness can be explained by the effect of the WGCs on ecological distribution and life history, i.e., the former becoming insignificant once the latter are included into the model. We stress that this study is an exploration of macroecological patterns consistent with particular groups of the abovementioned processes that influence performance and survival of species. This study cannot, and does not, aim at isolating and proving individual aspects of these processes such as local extinction.

METHODS

Characterization of species

Genome characters --Monoploid chromosome number (x) and ploidy level of German species were taken from Biolflor [START_REF] Klotz | BIOLFLOR: Eine Datenbank mit biologischökologischen Merkmalen zur Flora von Deutschland[END_REF]; https://wiki.ufz.de/biolflor/index.jsp, database last accessed July 14 2022), of species from Czech Republic from Šmarda et al. (2019), and of species from Dutch flora from Zonneveld (2019). Together, from these three floras chromosome numbers were available for 3473 species and ploidy levels for 3542 species, of the 72 families for which all variables had been available, representing 94% and 96%, respectively, of all species. We calculated the monoploid chromosome number as total chromosome number divided by ploidy levels. Since in Zonneveld (2019) ploidy levels were not provided for most of species, we used two other databases to infer ploidy levels for

Accepted Article

species in this flora, using total chromosome numbers in correspondent species for reference. Monoploid genome size was first defined as 1Cx-value [START_REF] Greilhuber | The origin, evolution and proposed stabili be nuclear DNA contents[END_REF], which is equivalent to 2C-values divided by the ploidy level. 1Cx-values were available for 2812 (77%) species in the combined data set of the three floras (available from all three mentioned above sources) with added data from The Plant DNA C-values database (release 7.1) [START_REF] Pellicer | The Plant DNA C-values database (release 7.1): an updated online repository of plant genome size data for comparative studies[END_REF] on species listed in the three floras. We used the data on 1Cx in picograms from Šmarda et al. (2019), and as 2C divided by ploidy levels of specimens with correspondent measurements from Bioflor. For the Dutch data we again needed a more complicated approach. To get 1Cx values from 2C values in Zonneveld ( 2019) we used information on ploidy and chromosome numbers from the other two sources. When multiple data were available for a character of a species, we calculated the arithmetic mean.

We note that 21% of species with ploidy data had variable ploidy levels, and 10% of species with chromosome number data had variable monoploid chromosome numbers. It may be argued that if within a species WGC parameters vary, the species should be split. However, splitting was not appropriate in our case: it would result in circularity between using WGC to define species and using WGC to explain the richness of these species. It would also lead to more splitting in species for which WGC have been more frequently studied increasing the probability of finding different WGC. And it would define species that botanists and ecologists cannot identify in the field when documenting local richness of families. Moreover, we could show that within-species variation of WGC is unlikely to have any impact on results of our analyses: We characterized average WGC per family across species based on either the per-species minimum, mean or maximum. We calculated for each family standardized effect sizes (SES) from these values as explained below. We finally compared for a given WGC the SESs based on per-species minima, means and maxima and found them to be very highly correlated (Pearson correlation: 0.995-0.999). The only exception was a relatively weak correlation (0.61) between SES of ploidy calculated from minimal and mean values per species. Overall, whatever extreme one takes from a within-species variation to calculate

Accepted Article

Characterization of families

family averages, the relative values are mostly practically identical, and at least similar, suggesting that the within-species variation did not bias our analyses. Finally, families with many species of unknown genomic variables did not score differently for means of the three genomic variables than more completely known families (correlations of means against completeness = -0.1006 to 0.0483), so that "correcting" for completeness is not needed and would even render the analyses less representative of the more poorly studied, rare families.

Life-history traits --We extracted 10 life-history traits (Tab. 1, including references) related to dispersal ability, reproductive capacities and responses to environmental variation. The selected traits are known to be related either to genome characteristics (such as stress tolerance or life span, e.g., [START_REF] Grime | Variation in genome size-an ecological interpretation[END_REF][START_REF] Grime | Plant Strategies, Vegetation Processes, and Ecosystem Properties[END_REF][START_REF] Husband | The incidence of polyploidy in natural plant populations: major patterns and evolutionary processes[END_REF] or to the ecological success of species and hence possibly to the numbers of species maintained per family [START_REF] Durka | Eine Datenbank mit biologisch-ökologischen Merkmalen zur Flora von Deutschland[END_REF][START_REF] Klotz | BIOLFLOR: Eine Datenbank mit biologischökologischen Merkmalen zur Flora von Deutschland[END_REF]. For life form we followed [START_REF] Veselý | Genome size and DNA base composition of geophytes: the mirror of phenology and ecology?[END_REF][START_REF] Veselý | Nutrient reserves may allow for genome size increase: evidence from comparison of geophytes and their sister non-geophytic relatives[END_REF][START_REF] Veselý | Environmental pressures on stomatal size may drive plant genome size evolution: evidence from a natural experiment with Cape geophytes[END_REF] in focusing on geophytes including in the definition of geophytes the presence of subterranean storage organs as such geophytes often have large genome sizes. Storage organs were bulb, hypocotyl bulb, shoot tuber, root tuber, runner with tuberous tip, primary storage root, secondary storage root, rhizome, or rhizome-like pleiocorm.

Distributions in ecological space --We characterized distributions along six abiotic environmental gradients, such as temperature, using Ellenberg indicator values (Tab. 1, [START_REF] Ellenberg | Indicator values of Central-European plants[END_REF]. Although they are based on expert knowledge (itself based on hundreds of original publications), these values have proven useful as a descriptor of species abiotic niches (see for instance, Diekmann, 2003, for a review). In addition, the relative position of species along these gradients has proven surprisingly constant across continents (Niinemets and Valladares, 2006). Such indicator values appear to be the only practical solution to account for niche axes related to soil reaction, moisture or light requirements when characterizing thousands of species of an entire flora.

Accepted Article

Traits -The appropriate level of phylogenetic resolution must ensure a sufficient number of species per phylogenetic lineage and a sufficiently large sample of lineages. These precautions help to avoid uncertainties due to incomplete sampling or reticulate evolution (Introduction).

We hence selected the family-level to conduct our core analyses. Angiosperm families are mostly monophyletic (APG IV, 2016) but, like any taxonomic level, to some degree arbitrary, as some families represent much older units than others and may have accumulated more species than others [START_REF] Wiens | The causes of species richness patterns across space, time, and clades and the role of "ecological limits[END_REF], but see [START_REF] Tank | Nested radiations and the pulse of angiosperm diversification: increased diversification rates often follow whole genome duplications[END_REF]. However, we note that our analyses control for phylogenetic non-independence among families (see next section), which identifies cases where families have similar species richness only because they are closely related and have similar age. There were 72 families for which information on all traits was available (details in Appendix S1, see the Supplementary Data with this article). Using the above-mentioned databases we characterized families by their regional mean values for WGC, life-history traits, and niche positions.

Species richness -We recorded for each family the number of species across the continental pool from which the regional flora is sampled. We defined this pool as Europe+Middle East +Mediterranean following The Euro+Med PlantBase (https://www.emplantbase.org/home.html), one of the main resources on current taxonomy and ranges of species and intraspecific taxa in the biogeographic realm to which the West Eurasian flora belongs. We calculated continental species richness in each Angiosperm family listed in the database using species lists available on the web-site and adjusted taxonomies of continental and regional floras according to The Euro+Med PlantBase. We log 2 -transformed species richness in order to ensure residual normality and homogeneity. We recorded "regional" species richness of families from the German database Biolflor (Biolflor online version at www.ufz.de/biolflor). Some local plots contained species not listed in Bioflor and many plots were close to Czechia or The Netherlands, two comparatively much smaller countries covered exclusively by vegetation formations and subformations also present in Germany [START_REF] Bohn | Map of the Natural Vegetation of Europe[END_REF][START_REF] Bohn | Map of the Natural Vegetation of Europe[END_REF]. We hence decided to include into the regional richness also species from Czechia and The Netherlands (from the respective complete databases of Šmarda et al. 2019 andZonneveld, 2019), just like it had been done for the genomic data. Regional richness was again log 2 -transformed. Databases at local to regional to continental (and up to global) scales may treat the same taxon differently: as accepted species (of hybrid origin) and include it, or as hybrid and then possibly exclude. They may also be more or less open to hybrids species as such. We nevertheless found that continental richness was by far the strongest predictor of regional richness (t>14.0, p <0.0001, Tab. 3), and regional richness was by far the strongest predictor of local richness (t>7.6, p <0.0001, Tab. 3). We finally recorded the mean local richness of species for each family across 193,449 plots, representing 2,195,946 species observations, of the German Vegetation Reference Database (GVRD, Jandt and Bruelheide, 2012). For each family, we included only plot records in which the respective family was present, as absence in the remaining plots reflects limited regional distribution rather than low local richness. Plot sizes follow standards in vegetation science (Mueller-Dombois and Ellenberg 1974), i.e. increase with the size of the dominant plants (ranging from few centimetres to many meters). A given family might maintain many species locally only because it grows in a location where most families maintain many species due to favorable environment or simply because the sampling plot in that location was excessively large. We hence recorded for each plot and target family also the local species richness of all other locally co-occurring species in the plot. We accounted for this "local richness of non-family members" as explanatory variables in the models explaining local species richness as depicted in Tables 3D, E, F. Throughout we accounted for both, native and exotic species, as many species may be introduced to a given locality but native to the region or introduced to the region but native to the continent. The issue of inclusion of exotics has likely little relevance as regional species richness of families without exotics related strongly to richness with exotics (r = 0.98), similarly to continental flora.

Accepted

Article

Phylogeny. A largely resolved, ultrametric, dated phylogeny of angiosperms for the study region based on rbcL gene was described in [START_REF] Hermant | Disparate relatives: Life histories vary more in genera occupying intermediate environments[END_REF] and further resolved in [START_REF] Bartish | Different habitats within a region contain evolutionary heritage from different epochs depending on the abiotic environment[END_REF]. To account for the families not included into the earlier phylogeny, we inferred a new phylogeny by adding the correspondent sequences of rbcL gene. We also

Accepted Article

Statistical analyses

Null models. Any relationship of a trait to richness risks suffering from a purely numerical bias: families of larger species richness are likely to converge on the overall mean tendency of a given trait. Despite the often highly asymmetric distributions of raw values, we found strong hump-shaped relationships between means of randomized trait values and the richness of families across which these trait values were randomized. Such a null-expected relationship will bias relationships between any trait and richness and such a shared bias will introduce major collinearities among explanatory variables, with tolerance values far below 0.1. For instance, using all three WGCs and their interaction terms (Tab. 3b) result in tolerances between 0.009 and 0.066. Such tolerances quantify the amount of variation in a given independent variable non-explained by other independent variables, and values of >= 0.1 are extended the data set by adding sequences of matK and ndhF genes for all the families, because increasing the sample of sequences improved the phylogenetic resolution and statistical support for the topology of the tree. We note that some poorly supported nodes in the tree were not congruent with the topology of the recently published tree based on Angiosperms353 genes [START_REF] Baker | A comprehensive phylogenomic platform for exploring the Angiosperm Tree of Life[END_REF]. Because the tree we obtained was similar to APGIV tree (Angiosperm Phylogeny Group 2016), these incongruencies were similar with those between Angiosperm353 and APGIV trees (see Supplementary Fig. S6 in Baker et al., 2016). According to [START_REF] Baker | A comprehensive phylogenomic platform for exploring the Angiosperm Tree of Life[END_REF], the nodes of incongruence between the trees were at the level of orders in APGIV and were generally weakly supported (mean LPP 0.75) in the Angiosperm353 tree. A list of species representing each family and Gene Bank codes for each of the species and genes we included in our phylogenetic analyses is provided in Appendix S2. We inferred the dated phylogeny following the same approach as used by [START_REF] Bartish | Different habitats within a region contain evolutionary heritage from different epochs depending on the abiotic environment[END_REF], i.e. employing Bayesian method and dating the tree by secondary calibrations available from literature for the main clades. The dated tree of all families included into our analyses is available in Appendix S3.

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considered tolerable; [START_REF] Dormann | Collinearity: a review of methods to deal with it and a simulation study evaluating their performance[END_REF]. In contrast, analyses based on the approach described below of standardizing by null-expectation yielded much lower multicollinearities and hence higher tolerances: 0.335-0.921. We hence opted to build our analyses entirely on trait values that were corrected for the hump shaped trait/richness relationship that occurs from random expectation. We did so by randomizing 1000 times trait values across species, calculating means and SDs of these randomized values for each family and then using these statistics to standardize observations by calculating standardized effect sizes (SES) as:

(observedmean randomized )/SD randomized ). For these randomizations, we used a Macro script for Excel (available from the first author). The SES calculations for all families and traits are reported in Appendix S1.

Relating genome characteristics to richness. All our analyses accounted for possible phylogenetic non-independence among families using a phylogenetic generalized least squared (PGLS) approach [START_REF] Grafen | The Phylogenetic Regression[END_REF], using the R package phytools [START_REF] Revell | phytools: an R package for phylogenetic comparative biology (and other things)[END_REF] and its default settings. PGLS has the advantage of not imposing corrections where phylogenetic nonindependence does not bias observed relationships between dependent and independent variables. In addition, data points represent families and not relative differences among families as in phylogenetically independent contrasts, which especially facilitates interpretation of interaction terms (interaction terms turned out to be essential). We tested multiple relationships of increasing complexity (head of Tab. 2). For consistency, we present all analyses only using the 72 families for which we have information on all variables used in the most complete analyses. We note, first, that "1Cx * ploidy level" and "basic chromosome number * ploidy level" correspond to holoploid C-value and holoploid chromosome number, respectively, while "1Cx * basic chromosome number" has no such equivalent. For all analyses, we graphically inspected the residual distribution (notably quantile-quantile, and predicted-vs.-observed) plots and excluded outliers where needed. We report results with and without residual outliers, and the identity of these outliers.

RESULTS

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After including interaction terms (Tab. 3B; Fig. 1a), regional richness declined with monoploid number of chromosomes, ploidy level and their combination (short expression for a negative interaction term, i.e. one variable intensifying the negative effect of another).

Regional richness also marginally significantly declined with high Cx combined with high ploidy (but only when the residual outliers Cyperaceae and Rosaceae were included).

Including richness of the continental pool (Tab. 3C) into the model maintained the decline of richness with ploidy level and with ploidy level combined with monoploid chromosome number.

Local species richness of families, i.e. means across localities where the respective family was present, ranged from 1 (multiple families) to 4.53 (Poaceae), i.e. log 2 = 0 to 2.18, (coefficient of variation of 131; coefficients of variation permit comparisons between variation around means that are bound to be very different). Regional species richness of the same families ranged from 1 (Portulacaceae) to 516 (Rosaceae), i.e. log 2 = 0 to 9.01 (coefficient of variation of 50). Within-family means of ploidy level ranged from 2 to 6 (multiple families each), within-family means of monoploid genome size ranged from 0.2 pg (Lentibulariaceae) to 22.07 pg (Liliaceae), within-family means of monoploid chromosome number from 4.75 (Callitrichaceae) to 21.50 (Oleaceae).

A qualitative summary of the observed relationships between WGCs of families and their regional or mean local richness is given in Tab. 2, which guides through the full analyses as provided in Tab. 3.

Regional richness

We first aimed d that without accounting for interactions between WGCs (Tab. 3A), regional species richness declined with the monoploid number of chromosomes but only when the residual outliers Liliaceae, Orchidaceae and Cyperaceae were excluded.

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Including mean local richness (rather than richness of the continental pool, Tab. 3D) maintained the decline of richness with ploidy, alone and in combination with high Cx.

After including both, continental and mean local richness (Tab. 3E), none of the relationships of regional richness to WGCs were maintained, while both continental and mean local richness were highly significant. This result suggests that the above relationships of WGCs to regional richness is to a large degree reflecting relationships at larger (continental) and smaller (local) scales.

Accounting in addition for niche characteristics and life histories of species (Tab. 3F) again showed no relationship between regional richness and WGCs.

After including interaction terms (Tab. 3B, Fig. 1b), mean local richness declined with ploidy level (independent of outlier exclusion) and with monoploid number of chromosomes and its combination with monoploid genome size (after exclusion of residual outliers Poaceae, Asteraceae, Fabaceae, Rosaceae and Cyperaceae).

Including richness of the regional pool (Tab. 3C) maintained the negative relationships of mean local richness to WGCs, most consistently with ploidy level and monoploid number of chromosomes: Across all data points, mean local richness declined with a large monoploid number of chromosomes and with a large monoploid chromosome number combined with a high ploidy level. After excluding the residual outliers Poaceae and Asteraceae, mean local

Mean local species richness

We then aimed at explaining mean local richness by WGCs. We found that without accounting for interactions between WGCs (Tab. 3A), mean local richness declined with ploidy level but only when the residual outliers Rosaceae, Poaceae, and Cyperaceae were excluded.

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richness declined with high ploidy and with high ploidy combined with high 1Cx as well as with high 1Cx combined with high monoploid chromosome number.

Including mean local richness of non-family members (rather than richness of the regional pool, Tab. 3D) maintained the negative relationships of mean local richness to WGCs, most consistently with ploidy level and monoploid numbers of chromosomes: Across all data points, mean local richness declined with monoploid chromosome number, ploidy level, and their combination. After excluding Poaceae, Asteraceae, Rosaceae, Liliaceae as residual outliers, mean local richness again declined with ploidy level, and with the combination of high ploidy level and high 1Cx value. Mean local richness also declined with monoploid numbers of chromosomes when combined with high 1Cx value, and declined with high 1Cx as such.

Including both, richness of the regional pool and mean local richness of non-family members (Tab. 3E), maintained the negative relationships of mean local richness to WGCs, most consistently with ploidy and monoploid numbers of chromosomes: Across all data points, mean local richness declined with monoploid numbers of chromosomes, alone and in combination with ploidy. After excluding Poaceae and Asteraceae as residual outliers, mean local richness declined with monoploid numbers of chromosomes combined with 1Cx. Mean local richness then also declined with ploidy level, alone or in combination with 1Cx.

Accounting in addition for species niche characteristics and life histories (Tab. 3F) did not change the conclusions, with ploidy level being significantly negatively related to mean local richness both alone and in combination with 1Cx, and monoploid chromosome number being negatively related to species richness in combination with 1Cx (analyses excluding Poaceae and Asteraceae as residual outliers, without exclusion no niche characteristics or life history traits had been selected).

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DISCUSSION

To our knowledge our study is the first to characterize the relationship between wholegenome characters (WGC) of lineages and the species richness of the same lineages at scales at which speciation is of little importance: within a young regional flora, and within the local species communities in which the respective families are present. While the fact that lineages differ in richness across an entire region is obvious and has been documented since centuries, the variation among lineages in the numbers of species that can co-occur in local ecological communities has only received little attention so far (see also [START_REF] Prinzing | High cooccurrence genera": weak but consistent relationships to global richness, niche partitioning, hybridization and decline[END_REF][START_REF] Večeřa | Mapping species richness of plant families in European vegetation[END_REF]. We here show that the coefficient of variation of mean local richness of families is even much higher than of regional richness. Families that are species-rich within occupied localities have low levels of ploidy, small numbers of monoploid chromosomes, intensified by the interaction of both. This relationship was independent of regional richness of these families and total richness of all locally co-occurring families. Across the entire region, we found that Angiosperm families that are regionally species-rich have a low level of ploidy and small monoploid chromosome numbers or both, but relationships disappeared after accounting for both the continental and mean local richness of families. Relationships between WGCs and species richness of families were maintained or even reinforced by accounting for niche characteristics or life histories.

There is the risk that the relationships we tested are biased by random effects of sampling small or large numbers of species from a trait distribution, or by phylogenetic nonindependence of families. We avoided both types of biases by standardizing trait means by a null model and applying phylogenetical generalized least squared models. In addition, variation of WGC within some of the species might suggest that, strictly, each of them consists of multiple biological species differing in WGC. However, such a definition of species based on WGC is inapplicable for vegetation scientists in the field [START_REF] Benton | Stems, nodes, crown clades, and rank-free lists: is Linnaeus dead?[END_REF][START_REF] Hillis | Constraints in naming parts of the Tree of Life[END_REF][START_REF] Majesky | How apomictic taxa are treated in current taxonomy: A review[END_REF], rendering any analysis of local richness impossible, and such a definition risks to introduce other biases as explained in Methods. To explore the

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impact of within-species variation of WGC on our analyses, we recalculated family values by averaging the within-species minima or maxima, and found that these per-family averages were almost always perfectly correlated to those obtained by averaging within-species means (Methods). Moreover, mean local richness was quantified based on vegetation plot records.

Vegetation plot records are snapshots that do not necessarily represent all species present across the year, in particular among short-lived species and life forms with dormant buds below the soil surface (Mueller-Dombois and [START_REF] Mueller-Dombois | Tolerance to shade, drought, and waterlogging of temperate northern hemisphere trees and shrubs[END_REF]. However, we found that including these (and other) species traits did not change the conclusions. Moreover, we here only consider families for which information on all traits and niche preferences is available, i.e., families well established in the region since at least many decades and observed in many plots, providing a robust data basis for quantifying mean local richness.

Finally, we note that our analyses are only valid for a given region and a given level of taxonomic resolution, the family. Our analyses should be repeated in other regions, notably such whose floras are older and may have been shaped more strongly by speciation (e.g., [START_REF] Rull | Speciation timing and neotropical biodiversity: the Tertiary-Quaternary debate in the light of molecular phylogenetic evidence[END_REF]. Analyses may also be repeated at coarser or finer levels of classification. Finer levels of classification such as that of genera likely show less variation in species richness than that of families, and recognition of apomictic species sometimes makes relatively small or even non-existent genera becoming comparatively more species-rich genera (e.g., Hieracium pilosella became a species-rich genus of its own, [START_REF] Jäger | anzen: Grundband[END_REF]. Coarser levels of classification might show a stronger signal of the continental species pool as an ultimate limit to maximum species richness. The family level might be the one at which units are particularly well established as monophyletic with strong statistical support (Durka and Michalski, 2012;[START_REF] Hermant | Disparate relatives: Life histories vary more in genera occupying intermediate environments[END_REF] for our flora), reflecting recent re-definitions based on molecular phylogenies (Angiosperm Phylogeny Group 2016).

Accounting for species richness of families from continental pools to local communities permitted interesting insights into the scale at which genomic characteristics might affect species richness. When analysing regional species richness of families, we found that

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accounting for either the continental pool or the mean local richness decreased the signal of monoploid number of chromosomes, and accounting for both made disappear also the number vs ploidy interaction. Therefore, the high regional species richness of families with few monoploid chromosomes and high ploidy might be explained by the high richness of the same families across the continental pool and locally. At the continental level, speciation probably contributes strongly to species richness (e.g., [START_REF] Rull | Speciation timing and neotropical biodiversity: the Tertiary-Quaternary debate in the light of molecular phylogenetic evidence[END_REF], at the local level richness is likely controlled by mechanisms of coexistence [START_REF] Prinzing | High cooccurrence genera": weak but consistent relationships to global richness, niche partitioning, hybridization and decline[END_REF][START_REF] Večeřa | Mapping species richness of plant families in European vegetation[END_REF]), which we will discuss below. When analysing mean local species richness of families, we found that accounting for the regional pool or for the richness of other co-occurring species did only result in minor changes, suggesting that processes operate indeed at the local level. We will hence focus our below discussion on the mean local richness of families, and on processes that may drive such local richness: the rate of local extinction and of local colonization. We will not further consider regional richness and the process that explains richness only at regional level: an increase in species turn-over between localities. We will also not further consider effects of genome size as the statistical signal of genome size was dependent on exclusion of residual outliers, i.e. outliers being particularly species-rich.

We found that mean local species richness of families decreases with an increase in ploidy level, alone or in interaction with an increased monoploid number of chromosomes. This result appears broadly consistent with the fact that in the study region and other temperate regions of the world polyploids are proportionally more frequent than in warmer regions (Rice et al., 2019), whereas species richness is lower than in warmer regions [START_REF] Mittelbach | Evolution and the latitudinal diversity gradient: speciation, extinction and biogeography[END_REF][START_REF] Qian | Phylogenetic trends and environmental correlates of nuclear genome size variation in Helianthus sunflowers[END_REF]. In contrast, this result seems inconsistent with the widely shared view that across the globe polyploidy fosters diversification and in particular extinction [START_REF] Wood | The frequency of polyploid speciation in vascular plants[END_REF][START_REF] Kraaijveld | Genome size and species diversification[END_REF][START_REF] Mayrose | Recently formed polyploid plants diversify at lower rates[END_REF]Soltis et al., 2014;[START_REF] Puttick | Size is not everything: rates of genome size evolution, not C-value, correlate with speciation in angiosperms[END_REF]. There is indeed growing evidence that, following severe biotic and abiotic environmental changes, polyploidization may provide selective advantages to descendants in the long run, such as higher survival than their preadapted diploid progenitors in the new environmental range [START_REF] Te Beest | The more the better? The role of polyploidy in facilitating plant invasions[END_REF][START_REF] Van De Peer | The evolutionary significance of polyploidy[END_REF], 2021). However,

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consistently with our results, it is known that the genomic shock following whole-genome merger and doubling (i.e. allopolyploidization) may temporarily trigger disadvantageous and detrimental effects in the early stages of the polyploids formation [START_REF] Comai | The advantages and disadvantages of being polyploid[END_REF][START_REF] Mayrose | Recently formed polyploid plants diversify at lower rates[END_REF]and refs above), and not all polyploids will be able to succeed and diversify in the long term (Van de Peer et al., 2017, 2021, andrefs therein). Previous studies argued that polyploidization might temporarily favour extinctions due to decreased individual fitness resulting from increasing cell size and hence slow life cycles of cells and the entire organism (Šimova and Herben, 2012;[START_REF] De La Torre | Contrasting Rates of Molecular Evolution and Patterns of Selection among Gymnosperms and Flowering Plants[END_REF], or from increased mutation rates [START_REF] Hedges | From the margins of the genome: mobile elements shape primate evolution[END_REF][START_REF] Pennisi | Jumping genes into the evolutionary limelight[END_REF]. Polyploid species also might suffer from inefficient natural selection due to the masking of each allele by multiple other copies [START_REF] Stebbins | Chromosomal Evolution in Higher Plants[END_REF][START_REF] Whitney | A role for nonadaptive processes in plant genome size evolution?[END_REF][START_REF] Mayrose | Recently formed polyploid plants diversify at lower rates[END_REF]. In consequence, polyploidy might at least temporarily have lower diversification rates through increasing extinction rates in the recent Quaternary past [START_REF] Mayrose | Recently formed polyploid plants diversify at lower rates[END_REF], albeit rates of global extinctions in polyploid species still remain under debate (see Soltis et al., 2014;Nieto Feliner et al., 2020;Wu et al., 2020;[START_REF] Van De Peer | Polyploidy: an evolutionary and ecological force in stressful times[END_REF]. Such extinctions might still be ongoing locally today. Among the above mechanisms affecting local extinction those operating via ecological performance such as increased stress or disturbance tolerance or slow life cycles may not be pertinent: accounting for stress or disturbance tolerance and life span did not change the negative relationships of polyploidy to mean local species richness (Tab. 3F). This leaves more evolutionary mechanisms involving mutation rates and efficiency of selection as possible mechanisms.

We found that mean local species richness of families decreases with an increase in chromosome number, alone or in combination with an increased ploidy level. We might imagine that a large number of chromosomes is disadvantageous through increasing the risk of chromosome mutations during mitosis [START_REF] Mayr | Animal Species and Evolution[END_REF], but the opposite would also be plausible: having many chromosomes is advantageous for the adaptive capacity of species as it decreases coupling of genes on the same chromosome [START_REF] Trickett | Recombination suppressors and the evolution of new species[END_REF].

However, little is known so far on how monoploid chromosome number affects the diversity

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that a lineage can maintain across the globe or within a region or locally. Across the globe, a large chromosome number has been shown to be related to increased invasiveness of species [START_REF] Pandit | The contrasting effects of genome size, chromosome number and ploidy level on plant invasiveness: a global analysis[END_REF]. In contrast, a large chromosome number is not related to speciation [START_REF] Levin | Rates of evolution in seed plants: Net increase in diversity of chromosome numbers and species numbers through time[END_REF]. The negative interaction term between monoploid chromosome number and ploidy level might reflect a disproportionally increased risk of mutations in chromosome number (aneuploidy, being highly deleterious) when chromosome number explodes due to polyploidization of a large monoploid chromosome number. In addition, in such a situation, cell cycles may be slowed down disproportionally (Torres et al., 2008). The negative effects of interaction terms between genomic variables might also potentially reflect reduced evolvability of each of the variables involved: chromosome number might more easily evolve if not replicated multiple times in a polyploid genomes, or if chromosomes are small. Ploidy might more easily evolve if the monoploid genome consists of only few chromosomes (Zenil-Ferguson et al., 2016). Such evolutionary changes, in turn, may contribute to local survival of populations (or at larger scales to speciation, [START_REF] Puttick | Size is not everything: rates of genome size evolution, not C-value, correlate with speciation in angiosperms[END_REF]. Other than invasiveness, the above mechanisms do not invoke ecological but evolutionary performance and hence cannot be controlled for including niche or life-history characteristics (Tab. 3F). Consistently, the statistical effects of monoploid number of chromosomes on mean local richness were maintained after including niche characteristics and life histories. We stress however, that these interpretations of our results remain speculative, and each needs to be tested explicitly in the future.

Small monoploid chromosome numbers and low ploidy levels ultimately corresponded to increased local co-occurrence of species within families, and such co-occurrence of related species may have consequences [START_REF] Webb | Phylogenies and community ecology[END_REF][START_REF] Prinzing | High cooccurrence genera": weak but consistent relationships to global richness, niche partitioning, hybridization and decline[END_REF][START_REF] Prinzing | Benefits from living together? Clades whose species use similar habitats may persist as a result of eco-evolutionary feedbacks[END_REF]. Cooccurrence among related species may require niche niche differentiation in space and time (MacArthur and Levins 1976), it may increase the load of natural enemies (Yguel et al., 2011) or permit sharing of defences against natural enemies [START_REF] Gerhold | The deep past controls the phylogenetic structure of present, local communities[END_REF], it may permit sharing of specialist mutualists or trigger competition for specialist mutualists [START_REF] Gerhold | Phylogenetic patterns are not proxies of community assembly mechanisms (they are far better)[END_REF], or nutrient recycling decomposers [START_REF] Pan | Larger phylogenetic distances in litter mixtures: Lower microbial biomass and higher C/N ratios but equal mass loss[END_REF], but see [START_REF] Barbe | Functionally or phylogenetically distinct neighbors turn antagonism among decomposing litter species into synergy[END_REF], and it

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increases the probability of hybridization [START_REF] Prinzing | High cooccurrence genera": weak but consistent relationships to global richness, niche partitioning, hybridization and decline[END_REF]. All these interactions are usually explained by particular functional relationships among the related species such as character displacement (Dyan and Simberloff, 2005;[START_REF] Prinzing | Less lineagesmore trait variation: Accepted Article phylogenetically clustered plant communities are functionally more diverse[END_REF][START_REF] Hermant | Disparate relatives: Life histories vary more in genera occupying intermediate environments[END_REF]. The present study suggests that such local co-occurrence of numerous species within particular families may in part result from these families having few chromosomesthrough low number of monoploid chromosomes or low ploidy numbers or both. Overall, the genomics of macroevolutionary lineages of plants might ultimately explain why species can ecologically coexist and interact in some lineages but not in others.

Conclusion

The major variation of species richness among angiosperm families within a region is a macroecological phenomenon (Martin and Husband, 2009), and so is the major variation in local species richness among families [START_REF] Večeřa | Mapping species richness of plant families in European vegetation[END_REF]. Obviously, much of this variation will reflect factors other than WGCs, such as environmental tolerances. Nevertheless, our study suggests that genome characteristics do play an important role, in particular the monoploid chromosome number and ploidy level, often independently of life histories or niche characteristics. Our results are consistent with existing theories on negative effects of high ploidy level or large numbers of chromosomes, mediated via evolutionary processes such as inefficient selection, increased number of lethal alleles, or selfish DNA. Our results suggest new hypotheses on the detrimental effects of having many chromosomes and contribute to understanding non-ecological drivers of ecological coexistence of species. Our study remains correlative and future case studies on individual lineages may help to identify true causation by inferring, for a lineage in a given region, the evolutionary sequence and hence possible causality among changes in WGCs, in niche occupation and in cladogenesis. Obviously, these studies should also involve other regions.

Table 2. Models explaining log 2 of species richness of families across the study region ("Regional"), and log 2 of mean richness within local vegetation plot records ("Local") by whole-genome characteristics (WGCs). This table shows only the direction of significant trends, while the parameter estimates and p-values are provided in Tab. 3 A to F, as specified in the last line. Explanatory variables are genomic characters without and with pairwise statistical interactions between these variables. The model involving interaction terms is then expanded by including other variables that might mediate or hide the statistical effect of WGCs on species richness per family: species richness of the same families in the respective species pool; mean local species richness of the same families or of co-occurring families, and life-histories and niche characteristics of the same families. 1Cx = Monoploid genome size; NbC = Number of monoploid chromosomes; Pl = Ploidy level; "-" = negative at p<0.05 (all significant results are negative), () = marginally significant 0.05 < p < 0.1, "0" = p ≥ 0.1. Where needed, results without │ with residual outliers are given. SES = standardized effect sizes. NA = not applicable. All analyses were carried out with phylogenetic generalized linear models to account for phylogenetic non-independence among families.

0│0 0│0 0│0 NA 0 N A 0 0 NbC -│0 -│- 0│0 NA 0 N A 0 0 Pl 0│0 -│- (-)│- NA (- ) N A 0 0 1Cx:Pl NA 0│(-) 0│0 NA - N A 0 0 NbC:Pl NA -│- -│- NA 0 N A 0 0 1Cx:NbC NA 0│0 0│0 NA 0 N A 0 0 Local: Mean species 1Cx 0│0 0│0 NA (- )│0 N A - │0 0│0 0│
0│0 0│- NA 0│- N A (- )│ -0│-0│ 1) Pl -│0 -│- NA - │0 N A - │--│0 -│ 1) 1Cx:Pl NA 0│0 NA - │0 N A - │0 -│0 -│ 1) NbC:Pl NA 0│- NA 0│- N A 0│ -0│-0│ 1) 1Cx:NbC NA 0│0 NA - │0 N A - │0 -│0 -│ 1)
full analysis in:

Tab. 3A

Tab. 3B, Fig. 1 Tab. 3C

Tab. 3D

Tab. 3E

Tab. 3F 1) analysis including outliers does not retain niche characteristics and traits Table 3. Models explaining species richness of families across the study region or within localities occupied by families within that region by monoploid size of genome (1Cx), monoploid number of chromosomes (NbC) and ploidy level (Pl). A-F show different models as outlined in Tab. 2. Some analyses suffer from residual outliers, often these residuals are major families. To provide comprehensive information we present analyses with and without outliers. The independent variable "pool richness" refers to the species richness of the respective families across the continental pool in the analyses explaining regional species richness of families, and it refers to the regional richness in the analyses explaining mean local richness of families. The independent variable "mean local richness" refers to the mean local richness of the respective family in analyses explaining regional species richness of families, and it refers to the mean local richness of co-occurring families in the analyses explaining mean local richness of families. Richness variables are log 2 -transformed. Trait and genomic variables are standardized effect sizes (SES, hence avoiding spurious random relationships resulting from randomly sampling a given number of species from a given trait distribution, see Methods). All analyses apply phylogenetic generalized linear models to account for phylogenetic non-independence among families. For WGC: Bold indicates p <0.05, underlined -0.05 ≤ p < 0.1. Note that in the analyses in F the following traits were never retained and are hence not presented: light preferences, continentality preferences, moisture preferences, pH preferences, lifespan, type of reproduction, breeding system, begin of flowering, duration of flowering, geophytes with storage organ, disturbance strategy, stress strategy, ln seed-mass, seed width, seed length. Results on WGC are qualitatively summarized in Tab. 2.

Figure 1 :

 1 Figure 1: Relationship between log 2 richness of species within families of angiosperms and standardized effect sizes (SES) of monoploid chromosome numbers, ploidy, and monoploid

Acknowledgements: IB and AP profited from an "ATIP" funding by CNRS. Valérie Briand provided technical support. We acknowledge the contribution of Ute Jandt in curating the

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German Vegetation Reference Database (GVRD), provided by institutional funds of Martin Luther University Halle-Wittenberg. The manuscript was considerably improved by thorough comments from Hanno Schaefer and two anonymous referees.

Author contributions: IVB, SB, AA and AP conceptualized and supervised the study, IVB and AP developed methodology, IVB, SB, HB and AP collected data and evidence, HG provided data, IVB, SB and HG curated data, MB developed software, IVB, SB and AP analysed the data, IVB and AP wrote the first draft of the manuscript, to which all authors contributed.

Data availability: Data used are from publicly available databases and are given in Appendices. In addition, a database is available at https://doi.org/10.25829/idiv.3532-fh8eya with all traits at species level, including information on whole-genome characters of 3906 species from Germany, The Netherlands and the Czech Republic.

Additional Supporting Information may be found online in the supporting information section at the end of the article Appendix S 1. Continental, regional and mean local richnesses of families and of locally co-occurring families (first to fourth variables); standardized effect sizes (SES) of WGCs (fifth to seventh variable) and of other traits considered (eighth to 24 th variable). Appendix S 2. List of species representing families in the inference of family phylogeny. Appendix S 3. A dated tree of all families included into our analyses.

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Literature cited

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Life-history traits

Stress tolerance

Ordinal, 0, 0.5, 1

Sensu [START_REF] Grime | Plant Strategies, Vegetation Processes, and Ecosystem Properties[END_REF] inferred from life histories 1)

Disturbance tolerance Ordinal, 0, 0.5, 1

Sensu [START_REF] Grime | Plant Strategies, Vegetation Processes, and Ecosystem Properties[END_REF]