Data from: No evidence for MHC class I based disassortative mating in a wild population of great tits

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.

主要组织相容性复合体（major histocompatibility complex，MHC）基因因可赋予后代适合度收益，被视作配偶选择的潜在关键靶标。根据互补基因假说，雌性会选择与自身MHC相异的雄性交配，以提升后代的免疫能力或规避近交衰退。本研究基于MHC基因型、平均氨基酸距离以及抗原结合位点的功能特性（MHC超型），旨在探究自然选择是否青睐于雌性对最大化相异或最优相异MHC I类类型的择偶偏好，并在野生大山雀种群中检验MHC类型相异性能否预测配偶间的亲缘关系。具体而言，我们在控制亲缘关系与空间种群结构的前提下，剖析MHC I类在雌性配偶选择决策中的作用，并考察配偶间MHC相容性对繁殖适合度的影响。我们未发现证据支持雌性基于最大化或最优MHC I类相异性选择配偶的假说。MHC等位基因共享与亲缘关系之间、MHC超型共享与亲缘关系之间仅存在微弱相关性，这表明功能变异层面的MHC相异性或许并非有效的亲缘关系指标。此外，配偶对的繁殖成功率并未随MHC相异性发生显著变化。本研究结果不支持‘自然选择青睐互补MHC类型的择偶偏好，或配偶选择实现了此类偏好’这一观点。