Gillingham Mark A F, Richardson David S, Løvlie Hanne, Moynihan Anna, Worley Kirsty, Pizzari Tom
Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, OX1 3PS, UK.
Proc Biol Sci. 2009 Mar 22;276(1659):1083-92. doi: 10.1098/rspb.2008.1549.
An increasing number of studies test the idea that females increase offspring fitness by biasing fertilization in favour of genetically compatible partners; however, few have investigated or controlled for corresponding preferences in males. Here, we experimentally test whether male red junglefowl, Gallus gallus, prefer genetically compatible females, measured by similarity at the major histocompatibility complex (MHC), a key gene complex in vertebrate immune function. Theory predicts that because some degree of MHC heterozygosity favours viability, individuals should prefer partners that carry MHC alleles different from their own. While male fowl showed no preference when simultaneously presented with an MHC-similar and an MHC-dissimilar female, they showed a 'cryptic' preference, by allocating more sperm to the most MHC-dissimilar of two sequentially presented females. These results provide the first experimental evidence that males might respond to the MHC similarity of a female through differential ejaculate expenditure. By revealing that cryptic male behaviours may bias fertilization success in favour of genetically compatible partners, this study demonstrates the need to experimentally disentangle male and female effects when studying preferences for genetically compatible partners.
越来越多的研究检验了这样一种观点，即雌性通过偏向于与基因相容的配偶受精来提高后代的适应性；然而，很少有研究调查或控制雄性相应的偏好。在这里，我们通过实验来检验雄性原鸡（Gallus gallus）是否更喜欢基因相容的雌性，这是通过主要组织相容性复合体（MHC）的相似性来衡量的，MHC是脊椎动物免疫功能中的一个关键基因复合体。理论预测，由于一定程度的MHC杂合性有利于生存能力，个体应该更喜欢携带与自己不同的MHC等位基因的配偶。虽然雄性原鸡在同时面对MHC相似和MHC不相似的雌性时没有表现出偏好，但当依次面对两只雌性时，它们会将更多的精子分配给MHC差异最大的那只，从而表现出一种“隐性”偏好。这些结果提供了首个实验证据，表明雄性可能通过不同的射精投入来对雌性的MHC相似性做出反应。通过揭示雄性的隐性行为可能会使受精成功偏向于基因相容的配偶，这项研究表明在研究对基因相容配偶的偏好时，有必要通过实验来区分雄性和雌性的影响。
