1 Max Planck Institute for Evolutionary Biology , August-Thienemann-Strasse 2, 24306 Plön , Germany.
2 Department of Developmental Immunology, Max-Planck-Institute for Immunobiology and Epigenetics , Stübeweg 51, 79108 Freiburg , Germany.
Biol Lett. 2018 Dec 21;14(12):20180730. doi: 10.1098/rsbl.2018.0730.
During mate choice decisions, females of many vertebrates use male olfactory cues to achieve immunogenetic optimality of their offspring. Three-spined sticklebacks ( Gasterosteus aculeatus) populating habitats that differ in their parasite communities evolve locally adapted combinations of genetic variants encoded at the major histocompatibility complex (MHC). Such adaptation confers optimal resistance to the local parasite fauna. Immunogenetic signatures co-evolved with local parasites favour population-specific assortative mate choice behaviour. Previous studies have shown that female sticklebacks evaluate male MHC-associated olfactory cues during the process of mate choice, but how habitat-specific information is exchanged between males and females has remained elusive. Here, we directly demonstrate the molecular nature of the olfactory cue providing habitat-specific information. Under controlled laboratory conditions, females that are ready to mate prefer mixtures of synthetic MHC peptide ligands mimicking the optimal allele number of their original population. These results imply that female sticklebacks can determine the number of MHC alleles of their prospective mates, compare it to their own immunogenetic status, and, if optimal with respect to the immunogenetic complementarity, accept the male as mate. Our results suggest a potentially common mechanism of ecological speciation in vertebrates that is based on the olfactory assessment of habitat-specific immunogenetic diversity.
在配偶选择决策中，许多脊椎动物的雌性利用雄性的嗅觉线索来实现后代的免疫遗传最佳状态。 三刺鱼（Gasterosteus aculeatus）生活在寄生虫群落不同的栖息地，它们会在主要组织相容性复合体（MHC）上的遗传变异体中进化出局部适应的组合。这种适应赋予了对当地寄生虫区系的最佳抗性。与当地寄生虫共同进化的免疫遗传特征有利于特定种群的有选择的配偶选择行为。先前的研究表明，雌性三刺鱼在配偶选择过程中会评估与 MHC 相关的雄性嗅觉线索，但雄性和雌性之间是如何交换特定栖息地信息的仍然难以捉摸。在这里，我们直接证明了提供栖息地特定信息的嗅觉线索的分子性质。在受控的实验室条件下，准备交配的雌性更喜欢模拟其原始种群最佳等位基因数量的合成 MHC 肽配体混合物。这些结果表明，雌性三刺鱼可以确定其潜在伴侣的 MHC 等位基因数量，将其与自己的免疫遗传状况进行比较，如果与免疫遗传互补性最佳，则接受该雄性作为伴侣。我们的研究结果表明，基于对特定栖息地免疫遗传多样性的嗅觉评估，这是脊椎动物中生态物种形成的一种潜在共同机制。
