Assessment of the Distribution of Seed Plants Endemic to the Lesser Antilles in Terms of Habitat, Elevation, and Conservation Status
The Lesser Antilles is part of the Caribbean biodiversity hotspot and a priority for conservation of its flora is its endemic taxa. Using data from herbarium specimen labels, we recently carried out a preliminary conservation assessment of the 263 seed plant taxa unique to these islands, reporting that 70% of them are potentially threatened. In an effort to make conservation recommendations for the threatened species, we have further analyzed the specimen data for patterns in their distribution. We found that just over ⅓ of the region’s endemics are restricted to a single island, and the majority of these are only found at a single location, whereas the others are found at multiple sites on each island. Diversity of regional endemics appears to be associated with larger islands, and while there appears to be a loose correlation between areas of high diversity of regional endemics and local endemism, there are a number of isolated centers of local endemism scattered across the island chain that may be of particular conservation concern. We also detected a relationship between diversity and elevation, with a peak in the number of endemic species occurred at midelevations (400–800 m). This correlation translates to a relationship between endemism and habitat type, with elevated numbers of endemics found in rainforest and elfin woodland, both communities that typically occur at mid- to high elevations, respectively. The highest proportion of threatened taxa is found in restricted and fragmented communities (elfin woodland, summit-herb vegetation, river bank, and moist forest) and the lowest proportion is found in the largest, most contiguous community (rainforest). Focused conservation action should occur in these important areas where plant endemism is locally high and habitat types are restricted and fragmented.