Behavioral and Physiological Differentiation between the Color Morphs of the Salamander, Plethodon cinereus

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Abstract
It is postulated that fitness differences between the color morphs of the salamander Plethodon cinereus are produced through selection on correlated characters and that character covariation plays an important role in the maintenance of the color polymorphism. A difference in temperature-dependent foraging behavior of the morphs was detected as a correlation between temperature and morph frequency on the ground surface at two sites near Princeton, New Jersey [(USA]). The standard metabolic rate of the morphs differs at 15.degree. C, at which the morphs'' behavior is most dissimilar. Age specific morph frequencies suggest that the striped morph suffers higher mortality in a warm locality whereas higher mortality of the black morph has been reported from other, colder, localities. These results, along with previous studies strongly support the hypothesis that the maintenance of this polymorphism is associated with fitness differences produced by temperature-related selection on characters correlated with coloration, namely metabolic rate and foraging behavior. The proportions of autotomized tails in the black and striped morphs in the study site were 21% and 4%, respectively, perhaps indicating higher predation on the black morph in this population. A previous hypothesis of protective coloration of the black morph is rejected on the basis of age-specific mortality and tail autotomy data.