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.

雌性会借助传递健康与活力信号的雄性性状来选择优质配偶，但部分种群间雌性偏好的雄性性状存在差异。若两种雄性性状均能如实反映雄性质量，则可通过雌性择偶偏好维持多种雄性性状，但针对这一推论的实证检验较为匮乏。雌性通过此类性状选择雄性，可直接从雄性处获得育雏协助等收益；但当雌性基于这些性状选择婚外配偶时，仅能获取雄性精子，或为后代带来间接遗传收益。在黄喉地莺（common yellowthroat, Geothylpis trichas）中，雌性对婚外配偶的择偶偏好指向两种不同的羽饰装饰：威斯康星种群偏好黑色面罩，纽约种群则偏好黄色胸斑。此前我们的研究发现，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类基因变异水平相关，而该变异水平恰恰预示着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。正如研究预期，纽约种群的黄色胸斑与MHC变异水平关联最为紧密，而该变异水平同样预示着更强的生存能力与血液寄生虫抗性。由此可见，两个种群的雌性所偏好的装饰性状存在差异，但这些不同的装饰所传递的雄性健康与遗传质量的信息维度高度相似，具体而言，均包含与MHC变异水平相关的信息，以及可为雌性带来潜在间接遗传收益的信号。