peciation and functional differentiation driven by polyploidization in Microhyla fissipes

Whole-genome duplications (WGDs) plays a significant role in evolution. In vertebrates, polyploids that survive after WGDs often obtain genome evolution and increased adaptability. However, it is rarely reported that how a recently formed polyploid population, especially autopolyploids, survive and compete with their diploid relatives. In this study, we report a newly discovered autopolyploid population of Microhyla fissipes on Hainan Island. Karyotyping and genomic sequencing analysis suggest that these tetraploids have derived from the polyploidization event of the diploid Microhyla fissipes ancestor around 4.04 million years ago. The differences in mating calls and the sterility of hybrid F1 offspring provide evidence of reproductive isolation between diploid and tetraploid M. fissipes. Compared to diploid M. fissipes, tetraploids possess a larger body size. The morphological and organ size adjustments, as well as the transcriptomic and metabolomic changes, contribute to the ability of autopolyploids to survive and adapt. Tetraploids exhibit the capacity to compete with diploids and establish themselves in the northeastern region of Hainan Island with plentiful rainfall. Meanwhile, their distribution is constrained by the high temperatures in the southwestern region due to the metabolic burden imposed by their body size. Our study will promote the understanding of the formation, survival, of autopolyploids and evolutionary significance of homologous polyploidy in vertebrates.