The rise of polyploids during environmental upheaval.

Polyploidy, or whole-genome duplication (WGD), serves as both a significant evolutionary force and a potential evolutionary dead end, particularly among angiosperms. Despite the prevalence of polyploid organisms, instances of ancient polyploidy are surprisingly rare, presenting a paradox that remains poorly understood. In this study, we constructed a comprehensive genomic dataset of 470 angiosperm species and dated 132 ancient WGD events that are non-randomly distributed, revealing a clustering around pivotal periods of environmental upheaval and extinction. Notably, our findings highlight a strong correlation between waves of paleopolyploidization and significant events such as the Middle Miocene Disruption, the Eocene-Oligocene Transition (EOT), the Paleocene-Eocene Thermal Maximum (PETM), the Cretaceous-Paleogene (K-Pg) extinction, and different oceanic anoxic events (OAEs). We propose that polyploid organisms have an increased chance of survival during times of great environmental turmoil, a conclusion with important implications in the context of contemporary climate change and rapid global warming.