Interspecific aggressive behaviour in salamanders: species-specific interference or misidentification?

Abstract

This research analyses variation in the interspecific aggressive behaviour of two salamander species, Plethodon jordani and P. glutinosus, from three localities which differ in extent of sympatry, the intensity of interspecific competition and frequency of hybridization. If interspecific aggression evolved by misidentification of species, it should either (1) vary concordantly with the frequency of hybridization, or (2) be similar in all of the localities. If selection for interspecific interference has occurred, interspecific aggression should vary concordantly with interspecific competition. Misidentification can account for variation in the interspecific aggressive behaviour of P. glutinosus, P. glutinosus from all localities did not distinguish behaviourally between heterospecifics and conspecifics. In contrast, for P. jordani, results suggest that alpha-selection has occurred under conditions of strong interspecific competition. P. jordani from the locality where interspecific competition is weak were less aggressive to heterospecifics than to conspecifics, while P. jordani from two localities where interspecific competition is strong were equally aggressive to heterospecifics and conspecifics.