Aligning conservation goals: are patterns of species richness and endemism concordant at regional scales?

Abstract

Biodiversity conservation strategies commonly target areas of high species richness and/or high endemism. However, the correlation between richness and endemism at scales relevant to conservation is unclear; these two common goals of conservation plans may therefore be in conflict. Here the spatial concordance between richness and endemism is tested using five taxa in North America: butterflies, birds, mammals, amphibians, and reptiles. This concordance is also tested using overall indices of richness and endemism (incorporating all five taxa). For all taxa except birds, richness and endemism were significantly correlated, with amphibians, reptiles, and the overall indices showing the highest correlations (r_s = 0.527-0.676). However, ‘priority sets’ of ecoregions (i.e., the top 10% of ecoregions) based on richness generally overlapped poorly with those based on endemism (< 50% overlap for all but reptiles). These results offer only limited support for the idea that richness and endemism are correlated at broad scales and indicate that land managers will need to balance these dual, and often conflicting, goals of biodiversity conservation.