An evaluation of sexual dimorphism in head size and shape of Red Salamanders (Pseudotriton ruber)

Abstract

For many secretive species of amphibians and reptiles, observations of reproductive behavior are limited to sparse anecdotes from the field or to animals held in captivity. However, a careful examination of morphological differences between the sexes can help shape hypotheses about behaviors with which they may be correlated. For example, sexual dimorphism in head size and shape are correlated with courtship, territoriality, and mate-defense behaviors in some salamanders. One widespread species with a poorly described reproductive natural history is the Red Salamander (Pseudotriton ruber). Here, we measure head size and employ geometric morphometric methods to evaluate head shape in P. ruber, with the goals of: 1) quantifying and visualizing sexual variation; 2) forming hypotheses about reproductive behavior. We found preliminary evidence for differences in head size and shape that are consistent with mate-guarding behavior, and we remark upon directions for future research.