Data from: Different ornaments signal male health and MHC variation in two populations of a warbler

Male traits that signal health and vigour are used by females to choose better quality mates, but in some cases the male trait selected by females differs among populations. Multiple male traits can be maintained through female mate choice if both traits are equally honest indicators of male quality, but tests of this prediction are rare. By choosing males based on such traits, females could gain direct benefits from males (assistance with parental care), but when females choose extra-pair mates based on these traits, females gain only male sperm, and potentially indirect genetic benefits for their offspring. In common yellowthroats (Geothylpis trichas), female choice of extra-pair mates targets two different plumage ornaments: the black mask in a Wisconsin population and the yellow bib in a New York population. Previously, we found that the black mask in Wisconsin is related to greater major histocompatibility complex (MHC) class II variation, which in turn signals better survival and disease resistance. In this study, we examined the signalling function of the yellow bib in New York to test whether it signals the same aspects of male quality as the black mask in Wisconsin. As predicted, we found that the yellow bib in New York is most closely associated with MHC variation, which also signals survival and resistance to blood parasites. Thus, the ornament preferred by females differs between the two populations, but the different ornaments signal similar aspects of male health and genetic quality, specifically information regarding MHC variation and potential indirect genetic benefits to females.

雌性个体可通过彰显健康与活力的雄性性状筛选品质更优的配偶，但不同种群间雌性偏好的雄性性状往往存在差异。若两种雄性性状均可如实反映雄性质量，则雌性配偶选择机制可维持多种雄性性状的共存，然而针对该推论的实证检验仍较为罕见。雌性基于此类性状选择配偶时，可从雄性处获得直接收益（例如育幼协助）；但当雌性选择婚外配偶时，仅能获取雄性精子，仅可能为后代带来间接遗传收益。在黄喉地莺（Geothylpis trichas）中，雌性对婚外配偶的选择偏好两种不同的羽饰：威斯康星种群青睐黑色面罩，而纽约种群则偏好黄色胸斑。此前本团队的研究显示，威斯康星种群的黑色面罩与更高的主要组织相容性复合体（major histocompatibility complex, MHC）Ⅱ类基因多态性相关，而该多态性可预示更强的生存能力与抗病性。本研究针对纽约种群的黄色胸斑的信号功能展开探究，以验证其是否与威斯康星种群的黑色面罩一样，能够反映雄性质量的相同维度。结果正如预期，纽约种群的黄色胸斑与MHC基因多态性高度相关，而该多态性同样可预示更强的生存能力与血液寄生虫抗性。综上，两个种群的雌性偏好不同的雄性装饰物，但这些差异化的装饰物所传递的雄性健康与遗传质量信息高度相似，具体均包含MHC基因多态性相关信息，以及可为雌性带来潜在间接遗传收益的信号。