Offspring viability benefits but no apparent costs of mating with high quality males

Abstract

Traditional models of sexual selection posit that male courtship signals evolve as indicators of underlying male genetic quality. An alternative hypothesis is that sexual conflict over mating generates antagonistic coevolution between male courtship persistence and female resistance. In the scarabaeine dung beetle Onthophagus taurus, females are more likely to mate with males that have high courtship rates. Here, we examine the effects of exposing females to males with either high or low courtship rates on female lifetime productivity and offspring viability. Females exposed to males with high courtship rates mated more often and produced offspring with greater egg-adult viability. Female productivity and lifespan were unaffected by exposure to males with high courtship rates. The data are consistent with models of sexual selection based on indirect genetic benefits, and provide little evidence for sexual conflict in this system.

Figure 1.

Effect of the number of males a female mated with and male quality on offspring viability (proportion of broods from which an adult beetle emerged). Females exposed to males with high courtship rates are depicted as solid symbols with a black least squares slope, and those exposed to males with low courtship rates are depicted as open symbols with a grey least squares slope.