Intermediate elevations support the highest tropical mammal diversity

Background/Question/Methods

Elevation is often considered an important driver of biodiversity patterns, with habitat zonation across elevation corresponding to different species assemblages. As a result, intermediate elevations may have higher richness due to their ability to host species from multiple elevational zones. However, most mammal studies on species richness-elevation relationship have focused on small mammals and showed either hump-shaped or linear relationships in temperate systems. It is therefore unclear how tropical mammal species richness, particularly for larger bodied species, varies with elevation. We used camera trap data for terrestrial mammals from 14 protected areas monitored by the Tropical Ecology Assessment and Monitoring (TEAM) Network. We employed a multi-species occupancy model to estimate each species’ occupancy as a function of camera-trap specific elevation for each protected area.

Results/Conclusions

We found that elevation was a significant predictor of community-level occupancy in many of the protected areas. Importantly, occupancy was highest at intermediate elevations in multiple protected areas as demonstrated by significant negative quadratic elevation terms, which provides evidence for the first time that community-level occupancy is generally highest at intermediate elevations for medium to large-bodied mammals in tropical regions. Mid-elevational occupancy peaks were stronger for protected areas in which camera traps sampled longer elevational gradients. Thus, our results from protected areas that cover a range of elevation gradients support the claim that relationships between elevation and species richness change from linear to quadratic as longer elevational gradients are sampled.