Leaf litter weevil richness increases with elevation in a tropical–temperate transitional forest in El Cielo Biosphere Reserve, northeastern Mexico

We studied communities of leaf litter weevils along a 2000 m elevation gradient in El Cielo Biosphere Reserve, northeastern Mexico, an area where Nearctic and Neotropical biotas overlap. After achieving high inventory completeness (0.922 site sample coverage), we encountered 81 weevil morphospecies, of which 55 were known to be leaf litter specialists. The diversity of leaf litter weevils increased with elevation. Beta diversity across the elevational gradient was mostly explained by species turnover rather than nestedness. The interaction between forest structure (measured as median DBH of trees) and precipitation seasonality explained more than 20% of the variation in weevil species richness: weevil richness showed a negative relationship with tree DBH and was positively associated with low climate seasonality variation, characteristics of tropical montane cloud forests. In contrast with insect taxa such as ants and dung beetles, which attain their highest richness at lower elevations, leaf litter weevil richness peaked at 1600 m. These results suggest that most litter weevil species are highly associated with a particular elevation range and the overall pattern of richness increasing with elevation is probably the result of an association of many weevil species with tropical montane cloud forest habitats, which occur close to the top of the mountain.

Abstract in Spanish is available with online material.