- Anchorage, AK (online)
The ferns and lycophytes of Japan (721 native taxa, including subspecies and varieties) are one of the best-studied pteridofloras in the world due to decades of research by both scientists and amateurs. Available datasets include distribution maps to 10-km resolution (covering nearly 100% of taxa), a plastid phylogeny (98%), morphological traits (98%), and chromosome counts (75%). However, most analyses of Japanese pteridophytes have been limited to patterns of species richness, and none have combined these datasets in an evolutionary context. Here, we integrate these data sources to explore the biodiversity of Japanese pteridophytes in depth. We find that different aspects of biodiversity are decoupled, varying across Japan in different ways. Although species richness is highest on Yakushima Island in southern Japan, phylogenetic diversity is greatest on the far southern islands of Okinawa, likely due to their tropical affinities. Furthermore, we observe correlations between sexual mode and phylogenetic endemism that may reflect evolutionary processes shaping pteridophyte biodiversity in Japan. Taken together, our analyses provide the most detailed picture to date of this remarkably diverse flora.