Does hybridization between divergent progenitors drive whole-genome duplication?

Hybridization and whole-genome duplication are both potential mechanisms of rapid speciation which sometimes act in concert. Recent surveys, showing that homoploid hybrid species tend to be derived from parents that are less evolutionarily divergent than parents of polyploid hybrid species (allopolyploids), have been interpreted as supporting a hypothesis that high divergence between hybridizing species drives whole-genome duplication. Here, we argue that such conclusions stem from problems in sampling (especially the omission of autopolyploids) and null model selection, and underestimate the importance of selection. The data simply demonstrate that hybridization between divergent parents has a higher probability of successfully producing a species if followed by polyploidization.