Reid Jane M, Wolak Matthew E
School of Biological Sciences University of Aberdeen Aberdeen United Kingdom.
Department of Biological Sciences Auburn University Auburn Alabama 36849.
Evol Lett. 2018 Jun 15;2(3):159-168. doi: 10.1002/evl3.56. eCollection 2018 Jun.
One key hypothesis explaining the evolution and persistence of polyandry, and resulting female extra-pair reproduction in socially monogamous systems, is that female propensity for extra-pair reproduction is positively genetically correlated with male reproductive fitness and consequently experiences positive cross-sex indirect selection. However, key genetic correlations have rarely been estimated, especially in free-living populations experiencing natural (co)variation in reproductive strategies and fitness. We used long-term life-history and pedigree data from song sparrows () to estimate the cross-sex genetic correlation between female propensity for extra-pair reproduction and adult male lifetime reproductive success, and thereby test a key hypothesis regarding mating system evolution. There was substantial additive genetic variance in both traits, providing substantial potential for indirect selection on female reproductive strategy. However, the cross-sex genetic correlation was estimated to be close to zero. Such small correlations might arise because male reproductive success achieved through extra-pair paternity was strongly positively genetically correlated with success achieved through within-pair paternity, implying that the same successful males commonly sire offspring produced by polyandrous and monogamous females. Cross-sex indirect selection may consequently have limited capacity to drive evolution of female extra-pair reproduction, or hence underlying polyandry, in systems where multiple routes to paternity success exist.
解释一妻多夫制的进化与延续以及在社会一夫一妻制系统中由此产生的雌性婚外繁殖现象的一个关键假说是，雌性婚外繁殖倾向与雄性繁殖适合度呈正遗传相关，因此经历正向的跨性别间接选择。然而，关键的遗传相关性很少得到估计，尤其是在经历繁殖策略和适合度自然（共同）变异的自由生活种群中。我们利用歌带鹀的长期生活史和系谱数据来估计雌性婚外繁殖倾向与成年雄性一生繁殖成功率之间的跨性别遗传相关性，从而检验一个关于交配系统进化的关键假说。这两个性状都存在大量的加性遗传方差，为对雌性繁殖策略的间接选择提供了很大潜力。然而，估计的跨性别遗传相关性接近于零。如此小的相关性可能是因为通过婚外父权获得的雄性繁殖成功与通过婚内父权获得的成功呈强正遗传相关，这意味着同样成功的雄性通常使一妻多夫制和一夫一妻制雌性所产的后代父系化。因此，在存在多种获得父权成功途径的系统中，跨性别间接选择推动雌性婚外繁殖进化的能力可能有限，进而推动一妻多夫制进化的能力也有限。
