Abstract
The theory of trade-off suggest that limited resources should lead to trade-off in resource intensive traits such as immunity related and sexually selected traits in males. Alternatively, sexual exaggerations can also act as an honest indicator of underlying immunocompetence, leading to positive correlations between these traits. Several studies have addressed this question using experimental evolution. However, they have rarely used ecologically relevant pathogens and fitness measurement (e.g., measuring post-infection survivorship) to find correlations between sexual selection and immunity. Here we attempt to address this caveat by evolving populations of Drosophila melanogaster under differential sexual selection. After more than hundred generations, we infected virgin and mated males from each population with three pathogenic bacteria: Pseudomonas entomophila (Pe), Staphylococcus succinus (Ss) and Providentia rettgeri (Pr). Fitness was measured as either post-infection survivorship (Pe and Ss) or bacterial clearance ability (Pr). Contrary to expectations, sexual selection had no evolutionary effect on male fitness against any of the pathogens. Moreover, mating had a beneficial effect against Pe and Pr, but no effect against Ss, suggesting pathogen specific phenotypic correlations between mating and immunity. Following these results, we discuss the significance of using ecologically relevant pathogens and quantifying host fitness while studying sexual selection-immunity correlations.
Footnotes
Conflict of Interest Statement: The authors have no conflict of interest.
Data archival location upon acceptance: Dryad
