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

Abstract

Male traits that signal health and vigour 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 (Geothylpis 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 major histocompatibility complex (MHC) class II variation, which in turn signals better survival and disease resistance. In this study, we examined the signalling 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.

Extra‐pair mating in a passerine bird with highly duplicated major histocompatibility complex class II: Preference for the golden mean

“…On the other hand, if females are not capable of self‐referencing, they might choose mates with an optimal MHC diversity. Choice of the most MHC‐diverse males has also been demonstrated in several taxa (e.g., fish [Reusch, Häberli, Aeschlimann, & Milinski, ], mammals [Ditchkoff, Lochmiller, Masters, Hoofer, & Bussche, ; Winternitz, Abbate, Huchard, Havlíček, & Garamszegi, ] and birds [Bonneaud et al, ; Dunn, Bollmer, Freeman‐Gallant, & Whittingham, ; Richardson, Komdeur, Burke, & von Schantz, ; Whittingham, Freeman‐Gallant, Taff, & Dunn, ]), while other studies have supported selection for males with an intermediate MHC diversity (e.g., Jäger et al, ; Slade, Watson, & MacDougall‐Shackleton, ). In contrast, Dearborn et al () suggested that the benefits of MHC‐based mate choice will be reduced in species with duplicated and diverged MHC loci, because diverse multilocus genotypes will then be inherited also under random mating.…”

MHC‐mediated sexual selection on birdsong: Generic polymorphism, particular alleles and acoustic signals

“…In birds, despite a list of evidence for MHC‐dependent mating (e.g., Dunn et al., ; Griggio et al., ; von Schantz et al., ; Whittingham et al., ), candidate mechanisms for MHC signalling remain yet to be explored (Slade et al., , ). This strikingly contrasts with our knowledge in other vertebrate taxa.…”

“…In animals that only partially rely on olfactory cues, condition‐dependent visual or behavioural traits can signal genetic resistance, because only males with high immunocompetence (as determined by their MHC genotype) can bear the costs of elaborated sexual displays (Folstad & Karter, ; Hamilton & Zuk, ). Accordingly, several studies in different taxa have shown that the expression of showy displays in males is related to MHC allelic diversity, heterozygosity or the presence of particular alleles or allele combinations (Ditchkoff, Lochmiller, Masters, Hoofer, & Van Den Bussche, ; Dunn, Bollmer, Freeman‐Gallant, & Whittingham, ; Griggio, Biard, Penn, & Hoi, ; von Schantz, Wittzell, Goransson, & Grahn, ; Setchell, Charpentier, Abbott, Wickings, & Knapp, ; Whittingham, Freeman‐Gallant, Taff, & Dunn, ).…”

Reciprocal translocation of small numbers of inbred individuals rescues immunogenetic diversity

“…; Whittingham et al . ). Starting from the 5' end, forward primer design included an 18‐bp partial MiSeq adapter (5′‐ACGACGCTCTTCCGATCT‐3′) followed by a 4‐bp index (individual barcode/tag; six different barcodes were used), and the MHC‐specific forward primer.…”