Article

Is mate choice in humans MHC-Dependent?

Department of Statistics, University of Oxford, Oxford, United Kingdom.
PLoS Genetics (Impact Factor: 8.17). 10/2008; 4(9):e1000184. DOI: 10.1371/journal.pgen.1000184
Source: PubMed

ABSTRACT In several species, including rodents and fish, it has been shown that the Major Histocompatibility Complex (MHC) influences mating preferences and, in some cases, that this may be mediated by preferences based on body odour. In humans, the picture has been less clear. Several studies have reported a tendency for humans to prefer MHC-dissimilar mates, a sexual selection that would favour the production of MHC-heterozygous offspring, who would be more resistant to pathogens, but these results are unsupported by other studies. Here, we report analyses of genome-wide genotype data (from the HapMap II dataset) and HLA types in African and European American couples to test whether humans tend to choose MHC-dissimilar mates. In order to distinguish MHC-specific effects from genome-wide effects, the pattern of similarity in the MHC region is compared to the pattern in the rest of the genome. African spouses show no significant pattern of similarity/dissimilarity across the MHC region (relatedness coefficient, R = 0.015, p = 0.23), whereas across the genome, they are more similar than random pairs of individuals (genome-wide R = 0.00185, p<10(-3)). We discuss several explanations for these observations, including demographic effects. On the other hand, the sampled European American couples are significantly more MHC-dissimilar than random pairs of individuals (R = -0.043, p = 0.015), and this pattern of dissimilarity is extreme when compared to the rest of the genome, both globally (genome-wide R = -0.00016, p = 0.739) and when broken into windows having the same length and recombination rate as the MHC (only nine genomic regions exhibit a higher level of genetic dissimilarity between spouses than does the MHC). This study thus supports the hypothesis that the MHC influences mate choice in some human populations.

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    • "There is increasing support for the suggestion that MHC constitution is olfactorily perceptible in a variety of taxa (Leinders-Zufall et al., 2004; Milinski et al., 2005; Radwan et al., 2008); hence, individual odour profiles are often predicted to be the cues for MHC dissimilarity. Major histocompatibility complex-based disassortative mating preferences have been reported across taxa, both in model species (Potts et al., 1991; Ober et al., 1997; Chaix et al., 2008) and in wild populations of nonmodel species (Consuegra & Garcia de Leaniz, 2008; Juola & Dearborn, 2011; – but see Huchard et al., 2010a). Although a number of studies suggested that females target MHC per se, by mating with MHC dissimilar (Landry et al., 2001; Miller et al., 2009) or optimally dissimilar males (Forsberg et al., 2007; Eizaguirre et al., 2009), other studies could not differentiate the role of inbreeding avoidance or MHC diversity on mate choice decisions (Freeman-Gallant et al., 2003; Setchell et al., 2010). "
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    ABSTRACT: Genes of the major histocompatibility complex (MHC) are regarded as a potentially important target of mate choice due to the fitness benefits that may be conferred to the offspring. According to the complementary genes hypothesis, females mate with MHC dissimilar males to enhance the immunocompetence of their offspring or to avoid inbreeding depression. Here, we investigate whether selection favours a preference for maximally dissimilar or optimally dissimilar MHC class I types, based on MHC genotypes, average amino acid distances and the functional properties of the antigen-binding sites (MHC supertypes); and whether MHC type dissimilarity predicts relatedness between mates in a wild great tit population. In particular, we explore the role that MHC class I plays in female mate choice decisions while controlling for relatedness and spatial population structure, and examine the reproductive fitness consequences of MHC compatibility between mates. We find no evidence for the hypotheses that females select mates on the basis of either maximal or optimal MHC class I dissimilarity. A weak correlation between MHC allele sharing and relatedness, and between MHC supertype sharing and relatedness suggests that MHC dissimilarity at functional variants may not provide an effective index of relatedness. Moreover the reproductive success of pairs did not vary with MHC dissimilarity. Our results provide no support for the suggestion that selection favours, or that mate choice realises, a preference for complimentary MHC types. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Journal of Evolutionary Biology 02/2015; 28(3). DOI:10.1111/jeb.12600 · 3.48 Impact Factor
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    • "The null results of previous studies might simply be attributed to lack of power due to small sample sizes in attempting to determine a complex human behavior with multiple intervening variables. Most recently Chaix et al. (2008) showed that MHC mate selection is apparent in European and American populations, but not in African Yoruba populations. However, the statistical methods of testing their hypothesis was criticized, because the significance could be attribute to extreme mate pairs within the groups, as well as for not correctly adjusting their statistical thresholds for multiple hypothesis testing (Derti et al., 2010). "
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    ABSTRACT: Qualitative-consciousness arises at the sensory level of olfactory processing and pervades our experience of smells to the extent that qualitative character is maintained whenever we are aware of undergoing an olfactory experience. Building upon the distinction between Access and Phenomenal Consciousness the paper offers a nuanced distinction between Awareness and Qualitative-consciousness that is applicable to olfaction in a manner that is conceptual precise and empirically viable. Mounting empirical research is offered substantiating the applicability of the distinction to olfaction and showing that olfactory qualitative-consciousness can occur without awareness, but any olfactory state that we are aware of being in is always qualitative. Evidence that olfactory sensory states have a qualitatively character in the absence of awareness derives from research on mate selection, the selection of social preference for social interaction and acquaintances, as well as the role of olfactory deficits in causing affective disorders. Furthermore, the conservation of secondary processing measures of olfactory valence during olfactory imagery experiments provides verification that olfactory awareness is always qualitatively conscious-all olfactory consciousness smells phenomenal.
    Frontiers in Psychology 07/2014; 5:713. DOI:10.3389/fpsyg.2014.00713 · 2.80 Impact Factor
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    • "It would be interesting to see whether individuals not only look to recognize and help relatives, but also under what circumstances it is relevant whether this relatedness is recent or ancestral. Furthermore, there is conflicting evidence about whether selection leads to mating patterns that encourage heterozygosity at major histocompatibility complex (MHC) loci, which would improve the immune response in the offspring (Chaix et al. 2008), and it would be interesting to find out whether a clearer picture could be derived using our segment-based coancestry . We therefore believe that this new measure of coancestry could be contrasted with other measures of coancestry under a variety of scenarios, especially those where the recent history of the population may alter the results, like in the estimation of recent effective population size or number of breeders from molecular coancestry (Nomura 2008). "
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    ABSTRACT: Conservation programmes aim at maximising the survival probability of populations, by minimising the loss of genetic diversity, which allows populations to adapt to changes, and controlling inbreeding increases. The best known strategy to achieve these goals is optimising the contributions of the parents, to minimise global coancestry in their offspring. Results on neutral scenarios showed that management based on molecular coancestry could maintain more diversity than management based on genealogical coancestry when a large number of markers is available. However, if the population has deleterious mutations, managing using optimal contributions can lead to a decrease in fitness, especially using molecular coancestry, because both beneficial and harmful alleles are maintained, compromising the long-term viability of the population. We introduce here two strategies to avoid this problem: The first one uses molecular coancestry calculated removing markers with low minor allele frequencies, as they could be linked to selected loci. The second one uses a coancestry based on segments of identity by descent, which measures the proportion of genome segments shared by two individuals because of a common ancestor. We compare these strategies under two contrasting mutational models of fitness effects, one assuming many mutations of small effect and another with few mutations of large effect. Using markers at intermediate frequencies maintains a larger fitness than using all markers, but leads to maintaining less diversity. Using the segment-based coancestry provides a compromise solution between maintaining diversity and fitness, especially when the population has some inbreeding load. This article is protected by copyright. All rights reserved.
    Molecular Ecology 10/2013; 22(24). DOI:10.1111/mec.12560 · 5.84 Impact Factor
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