The role of recent speciation in present-day patterns of tetrapod phylogenetic relatedness

AimBiodiversity is distributed unevenly among lineages and regions, and understanding the processes generating these global patterns is a central goal in evolutionary research, particularly in light of the current biodiversity crisis. Here, we integrate phylogenetic relatedness with species diversity patterns in four major clades of living tetrapods (amphibians, squamates, birds, and mammals) to approach this challenge. LocationGlobal. Time period300 million years ago - Present. Major taxa studiedTetrapods. MethodsWe studied geographic patterns of richness-corrected phylogenetic diversity (residual PD), identifying regions where species are phylogenetically more closely or distantly related than expected by richness. We explored the effect of different factors in residual PD: recent speciation rates, temporal trends of lineage accumulation, and environmental variables. Specifically, we searched for evolutionary and ecological differences between regions of high and low residual PD. ResultsOur results show heterogeneous spatial patterns of diversity dynamics across tetrapods. They reveal an overall negative relationship between recent speciation rates and residual PD, underscoring the role of recent speciation events in structuring current biogeographic patterns. Furthermore, we found differences between endothermic and ectothermic tetrapods in response to temperature and precipitation, highlighting the pivotal role of thermal physiology in shaping diversity dynamics. Main conclusionsGeographic patterns of diversity dynamics are heterogeneous across tetrapod clades and help us disentangle the evolutionary and ecological processes underlying them. By illuminating the multifaceted factors underpinning global diversity patterns, our study represents a significant advancement towards better understanding of how the present-day diversity of tetrapods was formed and how speciation rates influenced their species and phylogenetic diversity across clades and regions.