Data from: MHC genotype predicts mate choice in the ring-necked pheasant Phasianus colchicus

Females of several vertebrate species selectively mate with males on the basis of the major histocompatibility complex (MHC) genes. As androgen-mediated maternal effects have long-lasting consequences for the adult phenotype, both mating and reproductive success may depend on the combined effect of MHC genotype and exposure to androgens during early ontogeny. We studied how MHC-based mate choice in ring-necked pheasants (Phasianus colchicus) was influenced by an experimental in ovo testosterone (T) increase. There was no conclusive evidence of in ovo T treatment differentially affecting mate choice in relation to MHC genotype. However, females avoided mating with males with a wholly different MHC genotype compared with males sharing at least one MHC allele. Females also tended to avoid mating with MHC-identical males, though not significantly so. These findings suggest that female pheasants preferred males with intermediate MHC dissimilarity. Male MHC heterozygosity or diversity did not predict the expression of ornaments or male dominance rank. Thus, MHC-based mating preferences in the ring-necked pheasant do not seem to be mediated by ornaments’ expression and may have evolved mainly to reduce the costs of high heterozygosity at MHC loci for the progeny, such as increased risk of autoimmune diseases or disruption of coadapted gene pools.

多种脊椎动物的雌性会依据主要组织相容性复合体（MHC）基因选择性地与雄性交配。由于雄激素介导的母体效应对成年表型具有持久影响，交配与繁殖成功率可能取决于MHC基因型与个体在早期个体发育阶段暴露于雄激素的联合效应。我们研究了卵内睾酮（T）实验性升高如何影响环颈雉（Phasianus colchicus）基于MHC的配偶选择。尚无确凿证据表明，卵内睾酮处理会基于MHC基因型对配偶选择产生差异化影响。不过，相较于至少共享一个MHC等位基因的雄性，雌性会避免与MHC基因型完全迥异的雄性交配。雌性也倾向于避免与MHC完全相同的雄性交配，尽管这一趋势未达到显著水平。这些发现表明，雌性环颈雉更偏好MHC相似性处于中等水平的雄性。雄性的MHC杂合度或多样性无法预测其装饰性羽毛的表达与雄性优势等级。因此，环颈雉基于MHC的配偶偏好似乎并非通过装饰性羽毛的表达介导，其演化主要可能是为了降低后代MHC位点高杂合性带来的成本，例如自身免疫疾病风险升高或共适应基因库遭到破坏。