Data from: Different ornaments signal male health and MHC variation in two populations of a warbler

Male traits that signal health and vigor are used by females to choose better quality mates, but in some cases, the male trait selected by females differs among populations. Multiple male traits can be maintained through female mate choice if both traits are equally honest indicators of male quality, but tests of this prediction are rare. By choosing males based on such traits, females could gain direct benefits from males (assistance with parental care), but when females choose extra-pair mates based on these traits, females gain only male sperm, and potentially indirect genetic benefits for their offspring. In common yellowthroats (Geothlypis trichas) female choice of extra-pair mates targets two different plumage ornaments; the black mask in a Wisconsin population and the yellow bib in a New York population. Previously we found that the black mask in Wisconsin is related to greater MHC class II variation, which in turn signals better survival and disease resistance. In this study we examined the signaling function of the yellow bib in New York to test whether it signals the same aspects of male quality as the black mask in Wisconsin. As predicted, we found that the yellow bib in New York is most closely associated with MHC variation, which also signals survival and resistance to blood parasites. Thus, the ornament preferred by females differs between the two populations, but the different ornaments signal similar aspects of male health and genetic quality, specifically, information regarding MHC variation and potential indirect genetic benefits to females.