Exposing males to female scent increases the cost of controlling Salmonella infection in wild house mice
Source: Behavioral Ecology and Sociobiology, Volume 62, Number 6, April 2008 , pp. 895-900(6)
Abstract:Secondary sexual characters often provide indicators of a male's resistance to infectious diseases to rivals and potential mates, but it is unclear why. It is often suggested that males honestly signal their health due to energetic and other physiological trade-offs between investing into secondary sexual traits vs resistance to infectious diseases. Our aim was to determine whether such a trade-off exists using wild-derived male house mice (Mus domesticus). We exposed male mice to female scent, a manipulation that induces elevations in testosterone concentration and the expression of a variety of testosterone-mediated secondary sexual traits, and tested whether this sexual stimulation impaired the males' ability to resolve or cope with an experimental infection (Salmonella enterica). We kept the males on a controlled diet to prevent them from compensating by eating more food. We found that sexually stimulated males were able to control bacterial growth as effectively as sham-stimulated controls; however, to do so, they lost more body mass during infection compared to the controls. In contrast, we found no evidence that sexual stimulation reduced the body mass of uninfected male mice. These results indicate that males' responses to female odor are not immunosuppressive per se, yet they increase the energetic costs of controlling infection. Our findings support the idea that there is a physiological trade-off between secondary sexual signaling vs resistance to infectious diseases and suggest that studies using only immunocompetence assays might fail to detect such energetic trade-offs.
Document Type: Research article
Affiliations: 1: Konrad Lorenz Institute for Ethology, Austrian Academy of Sciences, Savoyenstraße 1a, 1160, Vienna, Austria, Email: S.Zala@klivv.oeaw.ac.at 2: Department of Biology, University of Utah, 257 S. 1400 E., Salt Lake City, UT, 84112, USA 3: Konrad Lorenz Institute for Ethology, Austrian Academy of Sciences, Savoyenstraße 1a, 1160, Vienna, Austria
Publication date: 2008-04-01