Experimental Evaluation of Population Interactions among Three Sympatric Species of Desmognathus

Population interactions among three species of salamanders in the genus Desmog- nathus (D. quadramaculatus, D. monticola, and D. ochrophaeus) were studied in the laboratory using an artificial stream system. These salamanders occur sympatrically and are known to partition the habitat along an aquatic-terrestrial gradient. The presence of D. quadramaculatus decreased the activity of D. monticola, but the reverse was not true. D. monticola negatively affected the spatial distribution of D. ochrophaeus. D. ochrophaeus depressed the level of activity of similarly sized D. monticola only. Larger species may represent a predatory threat to smaller species while com- petitive effects may be present among the smaller individuals of each species.