Origin of the complex (Athyriaceae).

We analyzed the phylogeny of the complex using plastid and low-copy nuclear marker DNA sequences. Based on allele constitution, triploid apogamous species of the complex appeared to have originated from the hybridization of triploid apogamous species and diploid sexual species by recurrent hybridization events. These results suggested that triploid apogamous ferns can achieve hybridization with diploid sexual species by producing diploid spores with irregular meiosis in sporogenesis. Furthermore, the present study predicted the involvement of several unknown species associated with hybridization. More sampling of species from China and adjacent areas is required to determine the relationships among unknown species and the complex.