Sympatric species of the salamander genus Desmognathus are distributed ecologically in a way that represents a typical example of species packing in response to interspecific competitive pressure. The series D. quadramaculatus-D. monticola-D. ochrophaeus-D. wrighti, or the same with D. aeneus substituted for D. wrighti, shows two trends: one toward increasing terrestrialism, and a parallel one toward decreasing size. The failure of D. fuscus to enter the series at White Top Mountain, Virginia, without replacing either D. quadramaculatus or D. monticola has been used as evidence that the community is saturated. The present paper presents evidence that questions previous interpretations and indicates that predation in and near streams has been more important than competition as the significant force in determining the evolution of the genus and the present structure of the community. The evidence consists of the size relationships, which are the reverse of what would be expected if competition had required increasing efficiency, the relative abundance of salamander predators in aquatic and terrestrial environments, and the failure of a majority of predictions about habitat shifts and size relationships when the predictions are based on the assumption of interspecific competition.
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Nelson G. Hairston (1980) studied this question.