Sizing up Strangers: Sexual Selection and Vocal Signals in Gelada Males.

[摘要] Sexual selection has led to the evolution of sexually-dimorphic traits, including ornaments, vocalizations, and displays, that reliably signal the condition or quality of the sender. By attending to these signals, animals gain information about the quality of a mate or the strength of a rival. Although sexually-selected signals are widespread across the animal taxa, signals in primates are rare. Primates typically rely on individual recognition, rather than signals, when assessing group mates. Consequently, our understanding of how primates convey, receive, and integrate information from signals into reproductive decisions remains poorly developed.This research examines a putative signal for male geladas (Theropithecus gelada) living in the Simien Mountains National Park, Ethiopia: a loud call given during male displays. The unusually large groups found in gelada society may have favored the evolution of signals as a way for males to quickly assess the competitive ability of unknown rivals. Determining if loud calls are sexually-selected signals requires establishing that: (1) variation exists across males of different quality, (2) males are able to distinguish between high and low quality males based on these calls, (3) receivers base reproductive decisions on these calls, and (4) males with high quality calls have higher reproductive success. To address these criteria, this research combines acoustic, experimental, hormonal, and behavioral analyses in a comprehensive study of a sexually-selected signal in a primate. This research has three main findings that further our understanding of the role of signals in primate communication. First, the rate of which males display and the acoustic properties of a male;;s call function as quality signals of a male;;s condition, androgen levels, and competitive ability. Second, gelada males, but not females, attend to differences in loud calls and do so with respect to both their own quality and the quality of the caller. Third, males with the highest quality calls sired the most offspring. These results indicate that gelada males attend to these loud calls when deciding which males to challenge.Geladas may be the exception among primates in relying exclusively on signals, rather than individual recognition, to assess rivals.

[发布机构] University of Michigan

[效力级别] sexual selection

[关键词] Theropithecus gelada;sexual selection;signals;assessment strategies;primate behavior;primate cognition;Anthropology and Archaeology;Psychology;Science;Social Sciences;Anthropology & Psychology PhD