Elevation is a stronger predictor of morphological trait divergence than competition in a radiation of tropical lizards

1. Adaptations for efficient performance are expected to shape animal morphology based on selection for microhabitat use and ecological forces. The presence of competitor species is predicted to cause niches to contract and enhance trait divergence. Therefore, increased species richness is expected to lead to greater trait divergence, and to result in reduced overlap and similarity between morphologies of sympatric species.

2. We examined patterns of morphospace occupancy and partitioning in the skink fauna of New Guinea, the world’s largest tropical island. Because skink species richness is largely decoupled from elevation in New Guinea, we could examine the effects of both factors (as proxies for competition and abiotic conditions), on morphospace occupancy and partitioning.

3. We measured 1860 specimens from 79 species of skinks throughout Papua New Guinea, and examined their morphospace occupancy in a spatial context. We calculated for each assemblage within equal-area cells, ...