A global phylogeny of turtles reveals a burst of climate-associated diversification on continental margins

Biodiversity is unevenly distributed across the tree of life. Understanding the factors that led to this unevenness can illuminate how macroevolutionary processes have interacted with changing global environments to shape patterns of biodiversity. By developing a comprehensive phylogeny for extant turtles and analyzing the diversification dynamics of the group, we show that species-level diversity is strongly associated with historical climate shifts. Our findings indicate that newly exposed continental margins created during a period of cooling and drying are important evolutionary cradles for turtle speciation, explain why turtle biodiversity is orders of magnitude more depauperate than the remaining major lineages of amniotes, and reconcile the seemingly contradictory insights that fossils and extant species suggest into a single picture of evolutionary diversification.