Meeting Abstract
Sexual signals are usually strongly linked to reproductive success and fitness. Because these signals are often but not always expressed more highly in one sex than the other, they can impose a sex-specific cost of reproduction. One mechanism whereby sexual signal expression can inflict a cost of reproduction is parasitism, which can reduce performance, survival, and reproduction. We tested the relationship between expression of a sexual signal (the dewlap) and ecological, morphological, and energetic factors mediating ectoparasite (mite) load in the Panamanian slender anole (Anolis apletophallus), using a combination of field and laboratory studies. We found that males were more highly parasitized than females, and that this relationship was driven by the preponderance of ectoparasites on the larger dewlap of males. Indeed, ectoparasite infection increased with both body size and dewlaps size in males but not females. We found no relationship between ectoparasite load and either habitat use or field-active body temperature. Energetics was related to parasite infection in a sex-specific fashion, as male anoles with smaller fat stores had higher mite loads, whereas there was no relationship between mite infection and fat body mass in females. In contrast, we found that the size of the gonads was positively associated with the number of mites in females, but not in males. Our results suggest that the expression of the sexual signal could incur a sex-specific fitness cost that is distinct from testosterone-based immunosuppression and may play a role in structuring life-history tradeoffs.
