Summary: Adams & Rohlf (2000)

Ecological character displacement describes the differences in morphology that occur between sympatric species due to interspecific competition, which allows them to coexist. In this study, Adams & Rohlf (2000) describe ecological character displacement between 2 terrestrial salamander species, Plethodon cinereus and P. hoffmani from two geographic transects in the USA. They quantified morphology of individuals from both allopatric and sympatric populations using linear measurements and landmark-based geometric morphometric methods. They also quantified food resource use by assaying stomach contents. Adams and Rohlf (2000) found morphological differences between sympatric, but not allopatric, populations in terms of prey consumption and segregation of prey according to size, although the resource bases for each population were similar. The reduction in prey consumption implied competition for food resources. The major anatomical difference was in relation to the functional and biomechanical properties of jaw closure. P. hoffmani has a faster, but weaker, jaw in contrast to P. cinereus, which has a slower but more powerful jaw. Adams & Rohlf's (2000) findings provide evidence that character displacement could the causal mechanism driving morphological differences between sympatric populations and provides an example of how anatomical differences can be identified among populations using geometric morphometrics.