Natural History Constrains the Macroevolution of Foot Morphology in European Plethodontid Salamanders

The natural history of organisms can have major effects on the tempo and mode of evolution, but few examples show how unique natural histories affect rates of evolution at macroevolutionary scales. European plethodontid salamanders (Plethodontidae: Hydromantes) display a particular natural history relative to other members of the family. Hydromantes commonly occupy caves and small crevices, where they cling to the walls and ceilings. On the basis of this unique and strongly selected behavior, we test the prediction that rates of phenotypic evolution will be lower in traits associated with climbing. We find that, within Hydromantes, foot morphological traits evolve at significantly lower rates than do other phenotypic traits. Additionally, Hydromantes displays a lower rate of foot morphology evolution than does a nonclimbing genus, Plethodon. Our findings suggest that macroevolutionary trends of phenotypic diversification can be mediated by the unique behavioral responses in taxa related to particular attributes of their natural history.