Marsit_et_al_Ploidy_data_2020

Hybridization and polyploidy are powerful mechanisms of speciation. Hybrid speciation often coincides with whole genome duplication (WGD). This suggests that WGD may impact the fate of hybrids by increasing access to adaptive mutations and/or restoring fertility. Alternatively, it has also been suggested that hybridization itself may increase the probability of WGD. Testing these models requires that we examine the rate of WGD in hybrids without the confounding effect of natural selection. By measuring the spontaneous rate of WGD of more than a thousand yeast crosses evolved under relaxed selection, we show that WGD can be triggered by hybridization. We also find that higher WGD rate correlates with higher genomic instability, and that WGD increases fertility and genetic variability. These results provide evidence that hybridization itself can promote WGD.