Institut de Biologie Intégrative et des Systèmes, Pavillon Charles-Eugène-Marchand, 1030 Avenue de la Médecine, Université Laval, Québec, Canada.
Proc Biol Sci. 2012 Jan 22;279(1727):379-86. doi: 10.1098/rspb.2011.0909. Epub 2011 Jun 22.
Major histocompatibility complex (MHC)-dependent mating preferences have been observed across vertebrate taxa and these preferences are expected to promote offspring disease resistance and ultimately, viability. However, little empirical evidence linking MHC-dependent mate choice and fitness is available, particularly in wild populations. Here, we explore the adaptive potential of previously observed patterns of MHC-dependent mate choice in a wild population of Atlantic salmon (Salmo salar) in Québec, Canada, by examining the relationship between MHC genetic variation and adult reproductive success and offspring survival over 3 years of study. While Atlantic salmon choose their mates in order to increase MHC diversity in offspring, adult reproductive success was in fact maximized between pairs exhibiting an intermediate level of MHC dissimilarity. Moreover, patterns of offspring survival between years 0+ and 1+, and 1+ and 2+ and population genetic structure at the MHC locus relative to microsatellite loci indicate that strong temporal variation in selection is likely to be operating on the MHC. We interpret MHC-dependent mate choice for diversity as a likely bet-hedging strategy that maximizes parental fitness in the face of temporally variable and unpredictable natural selection pressures.
主要组织相容性复合体（MHC）依赖性交配偏好已在脊椎动物类群中观察到，这些偏好有望提高后代的疾病抵抗力，并最终提高其生存能力。然而，目前几乎没有关于 MHC 依赖性择偶与适应性之间联系的经验证据，特别是在野生种群中。在这里，我们通过检查 MHC 遗传变异与成年生殖成功率和 3 年研究期间后代存活率之间的关系，探讨了先前在加拿大魁北克的野生大西洋鲑种群中观察到的 MHC 依赖性择偶模式的适应潜力。尽管大西洋鲑为了增加后代的 MHC 多样性而选择配偶，但实际上，在 MHC 相似度处于中等水平的配偶之间，其成年生殖成功率达到了最大值。此外，在 0+年和 1+年之间、1+年和 2+年之间的后代存活率模式，以及相对于微卫星基因座的 MHC 基因座的种群遗传结构，都表明 MHC 上可能存在强烈的选择时间变化。我们将 MHC 依赖性多样性择偶解释为一种可能的风险对冲策略，它在面对时空变化和不可预测的自然选择压力时，使亲代的适应性最大化。
