Reid Jane M, Arcese Peter, Keller Lukas F, Germain Ryan R, Duthie A Bradley, Losdat Sylvain, Wolak Matthew E, Nietlisbach Pirmin
School of Biological Sciences, Institute of Biological and Environmental Sciences, Zoology Building, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, Scotland.
Evolution. 2015 Jan;69(1):59-74. doi: 10.1111/evo.12557. Epub 2014 Dec 3.
Extra-pair reproduction is widely hypothesized to allow females to avoid inbreeding with related socially paired males. Consequently, numerous field studies have tested the key predictions that extra-pair offspring are less inbred than females' alternative within-pair offspring, and that the probability of extra-pair reproduction increases with a female's relatedness to her socially paired male. However, such studies rarely measure inbreeding or relatedness sufficiently precisely to detect subtle effects, or consider biases stemming from failure to observe inbred offspring that die during early development. Analyses of multigenerational song sparrow (Melospiza melodia) pedigree data showed that most females had opportunity to increase or decrease the coefficient of inbreeding of their offspring through extra-pair reproduction with neighboring males. In practice, observed extra-pair offspring had lower inbreeding coefficients than females' within-pair offspring on average, while the probability of extra-pair reproduction increased substantially with the coefficient of kinship between a female and her socially paired male. However, simulations showed that such effects could simply reflect bias stemming from inbreeding depression in early offspring survival. The null hypothesis that extra-pair reproduction is random with respect to kinship therefore cannot be definitively rejected in song sparrows, and existing general evidence that females avoid inbreeding through extra-pair reproduction requires reevaluation given such biases.
人们普遍假设，配偶外繁殖能使雌性避免与有社会配偶关系的近亲雄性进行近亲繁殖。因此，许多野外研究检验了两个关键预测：配偶外后代的近亲繁殖程度低于雌性的配偶内后代，以及配偶外繁殖的概率会随着雌性与其社会配偶雄性的亲缘关系增加而上升。然而，此类研究很少能足够精确地测量近亲繁殖或亲缘关系以检测细微影响，也很少考虑到因未能观察到在早期发育阶段死亡的近亲后代而产生的偏差。对多代歌带鹀（Melospiza melodia）谱系数据的分析表明，大多数雌性有机会通过与邻近雄性进行配偶外繁殖来增加或降低其后代的近亲繁殖系数。实际上，观察到的配偶外后代的近亲繁殖系数平均低于雌性的配偶内后代，而配偶外繁殖的概率会随着雌性与其社会配偶雄性之间的亲缘系数大幅增加。然而，模拟结果表明，此类影响可能仅仅反映了早期后代存活中近亲繁殖衰退所导致的偏差。因此，关于配偶外繁殖在亲缘关系方面是随机的零假设在歌带鹀中无法被明确拒绝，鉴于此类偏差，现有的关于雌性通过配偶外繁殖避免近亲繁殖的普遍证据需要重新评估。
