Lineage diversification and rampant hybridization among subspecies explain taxonomic confusion in the endemic Hawaiian fern Polypodium pellucidum.

Premise: Polypodium pellucidum, a fern endemic to the Hawaiian Islands, encompasses five ecologically and morphologically variable subspecies, suggesting a complex history involving both rapid divergence and rampant hybridization.

Methods: We employed a large target-capture data set to investigate the evolution of genetic, morphological, and ecological variation in P. pellucidum.