Environmental stress from abiotic conditions imposes physiological limits on communities. Stressful conditions can act as environmental filters on the individuals present in an assemblage or taxa available to colonize a given habitat. This can reduce a community’s diversity and make its composition more phylogenetically clustered. I tested this prediction using rove beetles (Staphylinidae, Coleoptera) collected across an elevation gradient in northwestern Costa Rica. Using DNA barcodes and phylogenetic estimates of community structure, I found high species turnover across elevation, and that staphylinid diversity (measured both through barcodes and phylogenetically) increased linearly with elevation. This diversity was negatively related to surface area and temperature, and positively with precipitation. I suggest that historical biogeography, rather than contemporary environmental stress alone, has produced these diversity patterns.