Data from: MHC, parasites and antler development in red deer: no support for the Hamilton & Zuk hypothesis

The Hamilton-Zuk hypothesis proposes that the genetic benefits of preferences for elaborated secondary sexual traits have their origins in the arms race between hosts and parasites, which maintains genetic variance in parasite resistance. Infection, in turn, can be reflected in the expression of costly sexual ornaments. However, the link between immune genes, infection, and the expression of secondary sexual traits has rarely been investigated. Here, we explored whether the presence and identity of functional variants (supertypes) of the highly polymorphic major histocompatibility complex (MHC), which is responsible for the recognition of parasites, predict the load of lung and gut parasites and antler development in the red deer (Cervus elaphus). While we found MHC supertypes to be associated with infection by a number of parasite species, including debilitating lung nematodes, we did not find support for the Hamilton-Zuk hypothesis. On the contrary, we found that lung nematode load was positively associated with antler development. We also found that the supertypes that were associated with resistance to certain parasites at the same time cause susceptibility to others. Such tradeoffs may undermine the potential genetic benefits of mate choice for resistant partners.

汉密尔顿-祖克假说（Hamilton-Zuk hypothesis）提出，偏好复杂次级性征所带来的遗传益处，起源于宿主与寄生虫之间的军备竞赛——该竞赛维持了宿主抗寄生虫抗性的遗传变异。反之，寄生虫感染状况可通过高成本性饰特征的表达得以体现。然而，免疫基因、感染与次级性征表达三者之间的关联，迄今鲜有研究探讨。本研究旨在探究：高多态性的主要组织相容性复合体（major histocompatibility complex, MHC）——其负责识别寄生虫——的功能变异体（超型，supertypes）的存在与否与类型，能否预测马鹿（Cervus elaphus）的肺部与肠道寄生虫负荷以及鹿角发育状况。研究结果显示，MHC超型与多种寄生虫物种的感染存在关联，其中包括致病性肺部线虫；但本研究未发现支持汉密尔顿-祖克假说的证据。与之相反，我们发现肺部线虫负荷与鹿角发育呈正相关关系。此外，我们还观察到，与部分寄生虫产生抗性的MHC超型，同时会导致宿主对其他寄生虫易感。这类权衡效应可能会削弱通过选择抗寄生虫配偶所获得的潜在遗传益处。