Department or Program
complementarity, high-throughput sequencing, mate choice, monophyly, Oceanodroma leucorhoa, seabird
Genes of the major histocompatibility complex (MHC) exhibit heterozygote advantage in immune defence, which in turn can select for MHC-disassortative mate choice. However, many species lack this expected pattern of MHC-disassortative mating. A possible explanation lies in evolutionary processes following gene duplication: if two duplicated MHC genes become functionally diverged from each other, offspring will inherit diverse multilocus genotypes even under random mating. We used locus-specific primers for high-throughput sequencing of two expressed MHC Class II B genes in Leach's storm-petrels, Oceanodroma leucorhoa, and found that exon 2 alleles fall into two gene-specific monophyletic clades. We tested for disassortative vs. random mating at these two functionally diverged Class II B genes, using multiple metrics and different subsets of exon 2 sequence data. With good statistical power, we consistently found random assortment of mates at MHC. Despite random mating, birds had MHC genotypes with functionally diverged alleles, averaging 13 amino acid differences in pairwise comparisons of exon 2 alleles within individuals. To test whether this high MHC diversity in individuals is driven by evolutionary divergence of the two duplicated genes, we built a phylogenetic permutation model. The model showed that genotypic diversity was strongly impacted by sequence divergence between the most common allele of each gene, with a smaller additional impact of monophyly of the two genes. Divergence of allele sequences between genes may have reduced the benefits of actively seeking MHC-dissimilar mates, in which case the evolutionary history of duplicated genes is shaping the adaptive landscape of sexual selection.
Dearborn DC, Gager AB, McArthur AG, Gilmour ME, Mandzhukova E, and Mauck RA. 2016. Gene duplication and divergence produce diverse MHC genotypes without disassortative mating. Molecular Ecology 25:4355-4367. https://doi.org/10.1111/mec.13747
Copyright © 2016 John Wiley & Sons Ltd. This is the author's version of the work. This publication appears in Bates College's institutional repository by permission of the copyright owner for personal use, not for redistribution.
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This is the peer reviewed version of the following article: Gene duplication and divergence produce diverse MHC genotypes without disassortative mating. Molecular Ecology 25:4355-4367, which has been published in final form at: https://doi.org/10.1111/mec.13747. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.