Interference Competition in Postmetamorphic Salamanders: Interspecific Differences in Aggression by Coexisting Species

Abstract

I examined whether interference competition occurred among the terrestrial juveniles of two pond—breeding salamanders, Ambystoma maculatum and A. talpoideum. In a laboratory experiment, I observed intra— and interspecific agonistic behavior between pairs of recently metamorphosed individuals by staging encounters between resident salamanders (i.e., possessors of a refugium) and (1) conspecific, (2) heterospecific, and (3) surrogate (control) intruders. Resident A. maculatum exhibited significantly more threat and submissive behavior to live intruders than to surrogates, with more agonistic behavior direct toward conspecifics than to heterospecifics. Intruders likewise exhibited significantly more threat and submissive behavior to conspecific residents than to heterospecific residents. In contrast, neither resident nor intruding A. talpoideum altered their behavior in response to differing types of opponents. These results indicate that interference competition may operate in the terrestrial environment. Further, the agonistic behavior of terrestrial Ambystoma is the antithesis of that of the larvae of these two species, which suggests an ontogenetic switch in behavior at metamorphosis. These data are the first indication of such a shift in competitive abilities in amphibians. This behavioral switch may sustain coexistence between these two species by counterbalancing the competitive advantage of one species in the aquatic stage with that of the other species in the terrestrial stage.

Coexistence of competitive species with a stage‐structured life cycle

“…There is some empirical evidence of reciprocal competitive abilities in the developmental stages of coexisting competing species with complex life cycles (Walls 1990;Mores et al 1999). Some scientists have postulated that such antagonism in competitive abilities may sustain coexistence of species by achieving a balanced interaction in which one species is competitively superior in the juvenile environment and the other species has a competitive advantage in the adult environment (Istock 1966;Zwolfer 1971;Schroder 1974;Briggs 1993;Holt and Polis 1997;Amarasekare 2000aAmarasekare , b, 2003.…”

The effects of food level and conspecific density on biting and cannibalism in larval long-toed salamanders, Ambystoma macrodactylum

“…Intraspecific aggression in animals can be influenced by a variety of factors including competition for food (Persson 1988;Drummond and Chavelas 1989), mates (Ovaska 1987), and space (Crowley et al 1987;Ducey and Ritsema 1988;Mathis 1990;Walls 1990). Intraspecific aggression, including cannibalism, has been documented in numerous amphibian species (see reviews in Fox 1975;Polis 1981;Polis and Meyers, 1985;Crump 1992;Mathis et al 1994).…”

The effects of conspecifics on burrow selection in juvenile spotted salamanders (Ambystoma maculatum)

“…However, few studies have focused on agonistic behavior between conspecifics of juvenile A. maculatum (Walls 1990;Smyers et al 2002).…”