Meeting Abstract
Chemical ecology of birds is a new and exciting area of research, and we have been exploring molecular signals contributing to odor profile and mate choice focusing on genes of the Major Histocompatibility Complex (MHC). The relationship between MHC, personal odor and mate choice has been the subject of heated controversy in natural populations, in part, due to the requirement for sufficiently large sample sizes to avoid Type I errors. To test whether MHC Class IIB plays a role in scent-based mate choice decisions, we have conducted a large-scale, multi-year study of Leach’s storm-petrels (Oceanodroma leucorhoa). We genotyped partial genomic fragments of two MHC Class IIB gene duplicates (Ocle-DAB1 and Ocle-DAB2) in nearly 1500 birds to characterize the MHC variability in a natural population and test for evidence of MHC-based disassortative mating. We used randomization tests to compare observed and bootstrapped medians of 4 MHC similarity metrics (pairwise heterozygosity differences, band-sharing coefficients, mean amino-acid substitutions, maximum amino acid substitutions) in 327 established pairs and found no significant evidence of disassortative mating (HZ: p=0.47; band-sharing: p=0.32; mean AA: p=0.27; maximum AA: p= 0.35). This sample size is unprecedented in any MHC study investigating disassortative mating in a wild population. We further show that test subjects can discriminate personal odors of conspecifics when MHC class IIB genotype is held constant (n=24, p<0.01, binomial test), suggesting that factors other than MHC class IIB contribute to personal odor discrimination in this species. These results provide one of the most definitive characterizations to date of the role (or lack thereof) of MHC Class IIB in individual odor discrimination and mate choice in a natural population.
