European Neogene rodent communities: explaining family-level replacements through a spatiotemporal approach

We analyse the changes in rodent regional assemblages based on 657 fossil-bearing western European localities distributed ranging from ca. 27 Ma (Late Oligocene) to ca. 3 Ma (Late Pliocene). We compare temporal and spatial patterns in order to identify the factors that drive the evolutions of communities. Regional assemblages are analysed based on the distribution of species richness among families. First, communities are temporally analysed to identify significant changes in their composition. Second, regional communities are spatially compared to indentify diversity gradients. The temporal analysis reveals that communities' evolution is marked by several breaks in their composition, related to either migration or environmental/climatic events. This evolution can be summarised in terms of shifts in the relative abundances of glirids, cricetids and murids within assemblages. In contrast, spatial analysis shows that only environmental changes induce long-lasting changes in diversity gradients. Some observations made on cricetids and murids extant relatives indicate that they have undergone a large dietary diversification enabled by a specific digestive tract (along with the diversification of other life-history traits), whereas glirids are more specialised. The opposite diversity dynamics of these groups emphasises the importance of family-level adaptive potential in diversity conservation issues when facing environmental changes.