Exploring dimensions of biodiversity in Japanese ferns

Abstract Aim To characterize multiple facets and drivers of biodiversity and understand how these relate to bioregions and conservation status. Location Japan Taxon Ferns Methods We used data from >300,000 fern specimens in Japan to compile a community dataset of 1,240 0.2° grid-cells including 674 native, non-hybrid taxa. We combined this with a phylogenetic tree and functional trait data to analyze taxonomic, phylogenetic, and functional diversity, and modeled the distribution of biodiversity in response to environmental factors and reproductive mode. We conducted categorical analysis of neo- and paleo-endemism to identify areas of significant phylogenetic endemism. We used hierarchical clustering of taxonomic and phylogenetic distances to analyze bioregions. We compared the overlap of significantly diverse grid-cells with existing conservation zones to assess conservation status. Results We observe three major patterns in the spatial distribution of biodiversity: that of taxonomic richness, which is highest at mid-latitudes, that of phylogenetic and functional diversity and phylogenetic endemism, which are highest in small southern islands, and that of relative phylogenetic and functional diversity, which are high at both high and low latitudes, and low at mid-latitudes. Grid-cells were grouped in to three (phylogenetic) or four (taxonomic) major bioregions. Temperature and apomixis were identified as likely drivers of patterns of taxonomic and phylogenetic diversity. Conservation status (% protected area) is generally higher than the overall rate for grid-cells with significantly high biodiversity. Main conclusions The integrative approach used here reveals previously undetected patterns and drivers of biodiversity in the ferns of Japan. The different distributions of each diversity type reflect the major bioregions. Although peak areas of different diversity types are largely non-overlapping, each one has a relatively high protection status. Despite this, future conservation efforts must be cognizant of dangers not addressed here such as climate change and herbivory by deer.