Sexual Size Dimorphism in the Red Hills Salamander, Phaeognathus hubrichti (Caudata: Plethodontidae: Desmognathinae)

Abstract

Body size is an important variable used in life-history and sexual selection theory to predict reproductive, behavioral, and ecological traits. Except for the presence of special skin glands in males, sexual dimorphism has not been reported in the Red Hills Salamander (Phaeognathus hubrichti), the basal member of the Desmognathinae. These data provide insight into the evolution of SSD (sexual size dimorphism) in the entire subfamily. We conducted multivariate and univariate tests on eight morphological measurements of 92 preserved P. hubrichti. We also examined specimens for broken tails and U-shaped scars, which may indicate bites from conspecifics. Male salamanders were larger than females in all measurements except tail length and had more scars than either females or juveniles. This species exhibited male-biased SSD in shape and size: males were broad and bulky, females were long and thin. Regression analysis showed differences in resource allocation between male and female salamanders. Differences in life-history strategies and sexual selection in the form of male-male combat may explain these differences in body size.