Proulx Research

OLDER MALES SIGNAL MORE RELIABLY Proulx, S.R., Day, T., and Rowe, L. Proceedings:Biological Sciences 269:2291-2299.

Abstract
The hypothesis that females prefer older males because they have higher mean fitness than younger males has been the center of recent controversy. These discussions have focused on the success of a female who prefers males of a particular age class when age cues, but not quality cues, are available. Thus, if the distribution of male quality changes with age such that older male shave on average genotypes with higher fitness than younger males, then a female who mates with older males has fitter offspring allowing the female preference to spread through a genetic correlation. We develop a general model for male display in a species with multiple reproductive bouts which allows us to identify the conditions which promote reliable signalling within an age class. Because males have opportunities for future reproduction,they will reduce their levels of advertising compared to a semelparous species. In addition, because higher quality males have more future reproduction, they will reduce their advertising more than low quality males. Thus, the conditions for reliable signalling in a semelparous organism are generally not sufficient to produce reliable signalling in species with multiple reproductive bouts. This result is due to the possibility of future reproduction, so that as individuals age and the opportunities for future reproduction fade signalling becomes more reliable. This provides a novel rationale for female preference for older mates: Older males reveal more information in their sexual displays.

<< Download this paper as a PDF >>