Meeting Abstract
Males often display ornaments that have presumably evolved as a result of sexual selection. Although male-male competition and female choice may favor the same or different ornaments, we expect that female choice will act on the ornament that is more revealing of male quality. We studied common yellowthroats (Geothlypis trichas) in two populations that differ in the male plumage ornament associated with female choice and male reproductive success. In Wisconsin females favor males with a larger black facial mask, a trait that is also related to immune function, survival and variation at immunity genes of the major histocompatibility complex (MHC). In New York females favor males with larger and brighter yellow bibs, a trait that is also associated with greater antibody production and survival. In this study, we examined whether the size and brightness of the yellow bib also reveals MHC variation for NY males. Using 454 pyrosequencing, we found that bib brightness was positively related to the number of MHC class II alleles with intermediate frequency and negatively related to the number of rare class II alleles, as predicted if the frequency of MHC alleles is influenced by host-parasite coevolution. Furthermore, males with more MHC class I alleles that were unique to NY had greater apparent survival, and resistance to malaria infection was associated with the presence of a particular MHC class II allele. Thus, similar to the black mask in WI, the yellow bib provides a signal to NY females that males have immunity genes that are related to parasite resistance and survival, consistent with good genes models of sexual selection.
