Meeting Abstract
The seasonal regulation and social responsiveness of androgens have been modeled by the Challenge Hypothesis, and one of the primary suggestions is that maintaining high levels of androgens can be costly. Indeed, many studies have suggested that high levels of androgens can reduce parental care, be immunosuppressive, and increase mortality rates. However, one potential cost of testosterone that has yet to be considered is that of reduced cooperative behavior. In many species, cooperation is key to reproduction and/or survival. Male wire-tailed manakins (Pipra filicauda), for example, perform coordinated male-male courtship displays, and males engage in long-term display partnerships with other males. Individual variation in cooperative behavior has fitness consequences, as more cooperative individuals have higher reproductive success. Here, we use both observational and experimental approaches to determine whether and how androgens mediate variation in cooperative behavior among male wire-tailed manakins. Observationally, we measured the relationship among display behavior, cooperative behavior, and circulating androgen levels. Experimentally, we measured display and cooperative behaviors before and after administering a testosterone implant. Our observational results show that individuals with higher levels of androgens engage in relatively fewer cooperative displays. Similarly, experimentally increased testosterone levels reduced the proportion of an individual’s displays that were cooperative. Our findings suggest that androgens mediate variation in male cooperative display behavior and that reduced cooperative behavior is a potential cost of high testosterone.
