Meeting Abstract
46.3 Wednesday, Jan. 5 Measuring Sexual Selection from Genetic Estimates of Effective Population Size in Lekking Manakins (Aves: Pipridae) MUSSER, J.M.*; BARKER, F.K.; PRUM, R.O.; Yale University; Univ. of Minnesota; Yale University jacob.musser@yale.edu
Members of the Neotropical manakins (Aves: Pipridae) have evolved lek mating systems with highly diverse characteristics including size, density, and a diverse repertoire of sound and visual displays employed by advertising males. Understanding the evolution of these systems requires knowledge of their underlying mechanics and intensity of sexual selection. However, measuring sexual selection in the field is challenging. Here, we take a novel population genetics approach to estimating the degree of sexual selection in manakin populations. Population genetics theory predicts that, in birds, an increase in the variance of male reproductive success is expected to have differential impacts on levels of genetic diversity in Z (sex) chromosomes versus autosomes. This is the result of an unequal distribution of Z chromosomes between the sexes (a majority residing in ZZ males) versus a more uniform distribution of autosomes. We tested this prediction by sequencing 10 autosomal and 10 Z-linked genetic loci to evaluate the impact of sexual selection in seven lekking manakin species, one lekking Cotingidae, and a putatively monogamous member of Tyrannidae. We find that all species show patterns of genetic diversity consistent with higher male reproductive skew than expected under monogamy. Additionally, species with concentrated leks (i.e. high densities of males) exhibit the greatest degree of sexual selection. Interestingly, the putatively monogamous Tyrannidae also shows patterns inconsistent with monogamy, however this result is complicated by evidence of recent selection in the Z chromosome. Our study is relevant for elucidating the evolution and mechanics of avian mating systems, and has implications for understanding the effect of sexual selection on genomes.
