Establishment of an allotetraploid fern species, Lepisorus yamaokae Seriz., between two highly niche-differentiated parental species.

Range shifts of the parental species during climatic oscillations in the Quaternary likely facilitated the formation and establishment of L. yamaokae. Further, the genetic intermediacy of L. yamaokae may have enabled a niche shift in its microenvironment, resulting in its successful establishment without a macroclimatic niche shift in L. yamaokae.