Institute of Biological and Environmental Sciences, School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen AB24 2TZ, UK.
Proc Biol Sci. 2011 Apr 7;278(1708):1114-20. doi: 10.1098/rspb.2010.1704. Epub 2010 Oct 27.
The forces driving the evolution of extra-pair reproduction in socially monogamous animals remain widely debated and unresolved. One key hypothesis is that female extra-pair reproduction evolves through indirect genetic benefits, reflecting increased additive genetic value of extra-pair offspring. Such evolution requires that a female's propensity to produce offspring that are sired by an extra-pair male is heritable. However, additive genetic variance and heritability in female extra-pair paternity (EPP) rate have not been quantified, precluding accurate estimation of the force of indirect selection. Sixteen years of comprehensive paternity and pedigree data from socially monogamous but genetically polygynandrous song sparrows (Melospiza melodia) showed significant additive genetic variance and heritability in the proportion of a female's offspring that was sired by an extra-pair male, constituting major components of the genetic architecture required for extra-pair reproduction to evolve through indirect additive genetic benefits. However, estimated heritabilities were moderately small (0.12 and 0.18 on the observed and underlying latent scales, respectively). The force of selection on extra-pair reproduction through indirect additive genetic benefits may consequently be relatively weak. However, the additive genetic variance and non-zero heritability observed in female EPP rate allow for multiple further genetic mechanisms to drive and constrain mating system evolution.
导致社会一夫一妻制动物中外群繁殖进化的驱动力仍存在广泛争议和未解决。一个关键假设是，雌性的外群繁殖是通过间接的遗传利益进化而来的，反映了外群后代的加性遗传价值增加。这种进化要求雌性产生由外群雄性受精的后代的倾向是可遗传的。然而，雌性的外群亲代（EPP）率的加性遗传方差和遗传力尚未被量化，这使得间接选择力的准确估计变得不可能。通过对社会一夫一妻制但遗传上多雄多雌的歌雀（Melospiza melodia）进行了长达 16 年的综合亲子关系和系谱数据研究，发现雌性后代中由外群雄性受精的比例具有显著的加性遗传方差和遗传力，构成了通过间接加性遗传利益进化外群繁殖所需的遗传结构的主要组成部分。然而，估计的遗传力适中较小（观察到的和潜在的隐性尺度上分别为 0.12 和 0.18）。因此，通过间接加性遗传利益对外群繁殖的选择力可能相对较弱。然而，在雌性 EPP 率中观察到的加性遗传方差和非零遗传力允许多种进一步的遗传机制来驱动和限制交配系统的进化。
