Comparative phylogeography investigates species’ recent histories, including range formation and long-term geographical isolation of populations. Thus, phylogeography is an important bridge between species history at evolutionary time-scales and population interactions at ecological time-scales and is an essential component of a unified and integrative view of ecological and evolutionary processes, especially for considering the spatial variability of those mechanisms at the continental scale. Phylogeographic break zones, or regions where turnover among intraspecific genetic lineages occurs for multiple species, have been proposed as critical regions where eco-evolutionary processes (e.g. dispersal limitation, drift, niche sorting) may be continuously acting over time. To determine whether this is true, and to tease apart the historical versus contemporary processes that shaped North American amphibian diversity and their consistency over time, we compiled amphibian survey data for >1200 North American assemblages and intraspecific phylogeographic data for 87 species. We first described taxonomic and phylogenetic diversities for North American amphibian assemblages. Then, we used variance partitioning methods to decouple the effect of environmental, spatial and phylogeographic structures on community diversity.
Results/Conclusions
First, although patterns of taxonomic and phylogenetic turnover were spatially consistent, our preliminary results highlighted spatial and taxon-specific variation in the factors explaining the largest amount of variance. Overall, we observed a significant influence of the phylogeographic structure on taxonomic and phylogenetic diversities. This effect was always observed for Urodela while it was not the case for Anura. In particular, community structure in eastern North America is jointly explained by phylogeography, environment and space while community diversity in the west is mainly influenced by the abiotic conditions. This result is consistent with the fact that the Eastern North America is well known to present a strong phylogeographic structure and thus our results suggest that the underlying processes of this structure have also resulted in divergence at higher levels. Overall, our results suggest a strong interplay between the different mechanisms underlying the current diversity structure, indicating that phylogeographic, environment and space need to be considered simultaneously if we are to better understand the structuring processes of the contemporary diversity.