Meeting Abstract
Some territorial animals recognize and respond less aggressively towards familiar neighbors relative to strangers. This common form of social recognition is not found in all territorial species and the social and ecological factors that favor its evolution, as well as the proximate mechanisms that make it possible, are poorly understood. We present results from a comparative study of two closely related species of rocket frogs (Aromobatidae) that defend different types of territories. We quantified habitat use and territory size of individual frogs over a four-year period and found that male golden rocket frogs (Anomaloglossus beebei) defend bromeliads for several years, which serve as reproductive resources for eggs and tadpoles. These resources are spatially clumped, putting males in close contact with neighbors. In contrast, male kai rocket frogs (A. kaiei), defend single-season calling territories on the forest floor that are not constrained by the distribution of reproductive resources. We tested for neighbor-stranger discrimination in these species with an aggressive threshold playback experiment and found that golden rocket frogs tolerate the calls of familiar neighbors at higher amplitudes than the calls of strangers, whereas kai rocket frogs do not behaviorally discriminate between the calls of neighbors and strangers. Whether neighbor-stranger discrimination in golden rocket frogs evolved in response to the greater value of the defended resource itself, or the greater social complexity that results from defense of clumped resources, is still an open question. Regardless, this system presents a great opportunity to examine the mechanisms of an independently evolved recognition system.
