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个体能够依据主要组织相容性复合体（major histocompatibility complex，MHC）基因，选择性地与雄性进行交配。由于雄激素介导的母体效应对成体表型具有持久影响，因此交配与繁殖成功率可能取决于MHC基因型与个体发育早期暴露于雄激素的联合效应。本研究探讨了实验性提升卵内睾酮（testosterone，T）水平对环颈雉（Phasianus colchicus）基于MHC的择偶行为的影响。研究未发现确凿证据表明，卵内睾酮处理会依据MHC基因型差异对择偶行为产生差异化影响，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。雌性还倾向于规避与自身MHC完全相同的雄性，尽管该趋势未达到统计学显著水平。上述研究结果表明，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求偶饰羽的表达情况与社会支配等级。由此可见，环颈雉中基于MHC的择偶偏好似乎并非通过求偶饰羽的表达来介导，其演化主要可能是为了降低子代MHC位点高杂合性带来的相关成本，例如自身免疫疾病风险升高或共适应基因库遭到破坏。