Institute of Biological and Environmental Sciences, School of Biological Sciences, Zoology Building, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK.
Proc Biol Sci. 2011 Nov 7;278(1722):3251-9. doi: 10.1098/rspb.2011.0173. Epub 2011 Mar 9.
It is widely hypothesized that the evolution of female extra-pair reproduction in socially monogamous species reflects indirect genetic benefits to females. However, a critical prediction of this hypothesis, that extra-pair young (EPY) are fitter than within-pair young (WPY), has rarely been rigorously tested. We used 18 years of data from free-living song sparrows, Melospiza melodia, to test whether survival through major life-history stages differed between EPY and WPY maternal half-siblings. On average, survival of hatched chicks to independence from parental care and recruitment, and their total lifespan, did not differ significantly between EPY and WPY. However, EPY consistently tended to be less likely to survive, and recruited EPY survived for significantly fewer years than recruited WPY. Furthermore, the survival difference between EPY and WPY was sex-specific; female EPY were less likely to survive to independence and recruitment and lived fewer years than female WPY, whereas male EPY were similarly or slightly more likely to survive and to live more years than male WPY. These data indicate that extra-pair paternity may impose an indirect cost on females via their female offspring and that sex-specific genetic, environmental or maternal effects may shape extra-pair reproduction.
广泛假设表明，在社会一夫一妻制物种中，雌性的额外交配繁殖反映了对雌性的间接遗传利益。然而，该假设的一个关键预测是，与配对内幼崽（WPY）相比，额外交配幼崽（EPY）更具适应性，但这一预测很少被严格检验。我们使用了 18 年来自自由生活的歌雀（Melospiza melodia）的数据，来检验 EPY 和 WPY 半同胞幼崽在主要生命史阶段的存活率是否存在差异。平均而言，孵化雏鸟到独立于亲代养育和招募的存活率，以及它们的总寿命，在 EPY 和 WPY 之间没有显著差异。然而，EPY 始终倾向于存活下来的可能性较小，而且招募的 EPY 存活的年限明显少于招募的 WPY。此外，EPY 和 WPY 之间的存活率差异具有性别特异性；雌性 EPY 独立和招募的存活率较低，寿命也比雌性 WPY 短，而雄性 EPY 存活和寿命较长的可能性与雄性 WPY 相似或略高。这些数据表明，通过其雌性后代，额外交配的父亲身份可能会对雌性造成间接成本，并且性别特异性的遗传、环境或母体效应可能会塑造额外交配的繁殖。
