Parasites and sexual selection: separating causes and effects

Hamilton and Zuk proposed a novel good genes mechanism of female choice based on heritable variation in resistance to parasites as indicated by male ornaments or showiness. This process predicts that 1) among different species, parasite levels should correlate with showiness, and 2) within any one species, males preferred by females should have low parasite burdens and exaggerated ornaments. A series of reports primarily assessing the second prediction provides evidence largely consistent with the Hamilton and Zuk mechanism, but this evidence does not exclude other possible processes of female choice. Future studies will need to address 1) the precise nature of the relationship between ornament development and parasite burdens independent of overall effects on host viability from parasites; 2) whether resistance to the parasites affecting ornament development is heritable; and 3) how host-parasite genotypes coevolve. -Author