Meeting Abstract
Genes of the Major Histocompatibility Complex (MHC) have been implicated in mate choice in a wide range of vertebrate taxa, with females of many species tending to prefer mates with MHC genotypes dissimilar to one�s own. However, this preference has not been observed in all taxa studied, and the factors that influence MHC-based mate choice in vertebrates is still an open question. We hypothesized that differing reproductive behaviors between species may affect whether females make MHC-based mate choices and what their preferences may be. We tested this hypothesis using two co-occurring species of Darters (small North American native fish) with differing reproductive behaviors. In Fantail Darters (Etheostoma flabellare), males provide parental care, while in Rainbow Darters (Etheostoma caeruleum) no parental care is provided. We performed mate choice experiments in which we presented females of both species with pairs of identical painted male models along with olfactory stimuli from live males with differing MHC genotypes, one with an MHC genotype similar to the focal individual�s and one with a dissimilar genotype. We measured the focal individuals� preference for the males using the amount of time the individual spent in each of two preference zones. Our early results indicate that female E. flabellare tend to prefer the scent of males with a similar MHC genotype while E. caeruleum females are split in their preferences, and the strength of preference differs between the species. We are currently evaluating our follow-up experiment testing whether females of either species prefer males with rare or common MHC genotypes within their local populations. Our research will provide insight into whether female MHC-mediated mate choice is influenced by differing reproductive behaviors and differing criteria for mates.
