Webster Joanne P, Hoffman Joseph I, Berdoy Manuel
Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3SY, UK.
Proc Biol Sci. 2003 Jul 22;270(1523):1481-5. doi: 10.1098/rspb.2003.2354.
Parasites have been proposed to be fundamental in the evolution of mate choice because differential mating on the basis of heritable disease resistance is expected to lead to progeny with a better genome-environment match than random mating. However, direct empirical data in support of this hypothesis are often lacking, and the relative influences of current and potential infection status (i.e. resistance genotype), and of mate choice versus mate conflict, remain largely unknown. We demonstrate experimentally, using simultaneous hermaphroditic snails (Biomphalaria glabrata) artificially selected for resistance or susceptibility to Schistosoma mansoni infection, that mate choice is influenced by a combination of current and potential parasitic infection status. As predicted by game-theory models, we also found a picture of conflict and cooperation: resistant and susceptible genotypes copulated in either gender and reciprocated (i.e. switched gender) equally when faced with an uninfected partner, but, by contrast, resistant snails actively refused to copulate as females with an infected partner. Such recognition and discrimination has implications for the maintenance of sex and the evolution of recognition systems.
寄生虫被认为在配偶选择的进化中至关重要，因为基于可遗传的抗病性进行差异交配，预计会产生比随机交配的后代具有更好的基因组与环境匹配度的子代。然而，通常缺乏支持这一假设的直接实证数据，并且当前和潜在感染状态（即抗性基因型）以及配偶选择与配偶冲突的相对影响在很大程度上仍不清楚。我们通过实验证明，使用人工选择出对曼氏血吸虫感染具有抗性或易感性的雌雄同体蜗牛（光滑双脐螺），配偶选择受到当前和潜在寄生虫感染状态的综合影响。正如博弈论模型所预测的，我们还发现了冲突与合作的情况：抗性和易感基因型在任何性别中都进行交配，并且在面对未感染的配偶时同等程度地进行性别互换（即角色转换），但相比之下，抗性蜗牛作为雌性会主动拒绝与感染的配偶交配。这种识别和歧视对性别的维持以及识别系统的进化具有重要意义。
