Increased bivalve cosmopolitanism during the mid-Phanerozoic mass extinctions

Abstract

The impact of mass extinctions on biogeographic patterns remains unclear. Analysis of large-scale biogeographic patterns can provide insights into macroevolutionary processes. Here, we aim to trace the biogeographic dynamics of bivalves from the Middle Permian to the Early Jurassic based on an updated dataset, including 25,891 bivalve occurrence data, by using biogeographic connectedness (BC) and multiple-site β-diversity measures. The results reveal a significant bivalve cosmopolitanism event following the Permian–Triassic mass extinction (PTME) and a possible cosmopolitanism event after the Triassic–Jurassic mass extinction (TJME). Analysis of the BC of survivors and newcomers in each event reveals that both potential cosmopolitanism events were related to the selective extinction of endemic taxa, suggesting that endemics are more vulnerable during mass extinctions. The geographic expansion of survivors also possibly contributed to the cosmopolitanism in the aftermath of the PTME, supporting the ecological release hypothesis following the PTME. Finally, we found that the spatial sampling heterogeneity can bias biogeographic patterns, for instance, bivalve cosmopolitanism after the TJME.