Bonneaud Camille, Chastel Olivier, Federici Pierre, Westerdahl Helena, Sorci Gabriele
Laboratoire de Parasitologie Evolutive, CNRS UMR 7103, Université Pierre et Marie Curie Paris 6, 7 quai St Bernard, bât. A 7ème étage, case 237, Paris 75252 Cedex 05, France.
Proc Biol Sci. 2006 May 7;273(1590):1111-6. doi: 10.1098/rspb.2005.3325.
The extreme polymorphism of the vertebrate major histocompatibility complex (Mhc) is famous for protecting hosts against constantly evolving pathogens. Mate choice is often evoked as a means of maintaining Mhc variability through avoidance of partners with similar Mhc alleles or preference for heterozygotes. Evidence for these two hypotheses mostly comes from studies on humans and laboratory mice. Here, we tested these hypotheses in a wild outbred population of house sparrows (Passer domesticus). Females were not more or less closely related to the males they paired with when considering neutral genetic variation. However, males failed to form breeding pairs when they had too few Mhc alleles and when they were too dissimilar from females at Mhc loci (i.e. had no common alleles). Furthermore, pairs did not form at random as Mhc diversity positively correlated in mating pairs. These results suggest that mate choice evolves in response to (i) benefits in terms of parasite resistance acquired from allelic diversity, and (ii) costs associated with the disruption of co-adapted genes.
脊椎动物主要组织相容性复合体（Mhc）的极端多态性以保护宿主抵御不断进化的病原体而闻名。配偶选择常被认为是通过避免与具有相似Mhc等位基因的伴侣配对或偏好杂合子来维持Mhc变异性的一种方式。这两种假说的证据大多来自对人类和实验室小鼠的研究。在这里，我们在野生远交家麻雀（Passer domesticus）群体中对这些假说进行了测试。考虑中性遗传变异时，雌性与它们配对的雄性之间的亲缘关系并无远近之分。然而，当雄性的Mhc等位基因过少以及它们在Mhc基因座上与雌性差异过大（即没有共同等位基因）时，它们无法形成繁殖对。此外，配偶对并非随机形成，因为配偶对中的Mhc多样性呈正相关。这些结果表明，配偶选择的进化是为了应对：（i）从等位基因多样性中获得的寄生虫抗性益处，以及（ii）与共适应基因破坏相关的成本。
