Mathematical Biology Seminar

Date: November 22, 2021

Time: 3:00PM - 4:00PM

Location: BLOC 302

Speaker: Colton Watts, Texas A&M University

Title: The evolution of sexual signaling in female animals

Abstract: Sexual selection theory predicts that costly sexual signals can evolve if they provide an advantage in competing for limited mating opportunities. However, this framework struggles to explain empirical systems in which sexual signals have evolved in the limiting sex, such as in females of polygynous species. We explore whether a sexual signal can evolve in females of polygynous species if it increases the likelihood of associating with "high-quality" males that provide social benefits (e.g., increased survival) to their partners. Using a population genetic approach, we show that such a signal can spread in the population if there is variation in male quality and the marginal social benefit of mating with high-quality males is much larger than the costs to females of signaling. However, the ultimate fate of the signal depends on the costs to males of providing social benefits to their partners. If these costs are low enough that the high-quality male genotype can approach fixation, then the benefit of female signaling becomes negligible because even non-signalers are likely to associate with benefit-providing males. In this case, any costs of the signal will lead to its extinction following an initial increase in frequency. If, however, the costs to high-quality males are large enough to prevent fixation, the quality and signal loci can undergo damped oscillations to a coevolutionary equilibrium characterized by a low frequency of signaling genotypes and a high frequency of high-quality genotypes. Thus, our model demonstrates that sexual signals may evolve in the limiting sex by increasing access to high-quality partners, though the conditions under which this occurs are somewhat restrictive.