Institute of Biological and Environmental Sciences, School of Biological Sciences, Zoology Building, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK.
Proc Biol Sci. 2012 Nov 22;279(1747):4652-60. doi: 10.1098/rspb.2012.1835. Epub 2012 Sep 19.
The evolutionary forces that underlie polyandry, including extra-pair reproduction (EPR) by socially monogamous females, remain unclear. Selection on EPR and resulting evolution have rarely been explicitly estimated or predicted in wild populations, and evolutionary predictions are vulnerable to bias due to environmental covariances and correlated selection through unmeasured traits. However, evolutionary responses to (correlated) selection on any trait can be directly predicted as additive genetic covariances (cov(A)) with appropriate components of relative fitness. I used comprehensive life-history, paternity and pedigree data from song sparrows (Melospiza melodia) to estimate cov(A) between a female's liability to produce extra-pair offspring and two specific fitness components: relative annual reproductive success (ARS) and survival to recruitment. All three traits showed non-zero additive genetic variance. Estimates of cov(A) were positive, predicting evolution towards increased EPR, but 95% credible intervals overlapped zero. There was therefore no conclusive prediction of evolutionary change in EPR due to (correlated) selection through female ARS or recruitment. Negative environmental covariance between EPR and ARS would have impeded evolutionary prediction from phenotypic selection differentials. These analyses demonstrate an explicit quantitative genetic approach to predicting evolutionary responses to components of (correlated) selection on EPR that should be unbiased by environmental covariances and unmeasured traits.
导致一妻多夫制的进化力量，包括社会一夫一妻制雌性的额外交配（EPR），仍不清楚。EPR 的选择以及由此产生的进化在野生种群中很少被明确估计或预测，而且由于环境协方差和通过未测量特征的相关选择，进化预测容易产生偏差。然而，对任何特征（相关）选择的进化反应都可以通过适当的相对适合度成分直接预测为加性遗传协方差（cov(A)）。我使用了来自歌雀（Melospiza melodia）的综合生活史、亲子关系和系谱数据，来估计雌性产生额外后代的倾向与两个特定的适合度成分之间的 cov(A)：相对年生殖成功率（ARS）和招募时的存活率。所有三个特征都表现出非零的加性遗传方差。cov(A)的估计值为正，预测了向更多 EPR 的进化，但 95%置信区间与零重叠。因此，由于通过雌性 ARS 或招募进行（相关）选择，EPR 没有明显的进化变化预测。EPR 和 ARS 之间的负环境协方差会阻碍从表型选择差异中进行进化预测。这些分析证明了一种明确的定量遗传方法，可以预测对 EPR 的（相关）选择组成部分的进化反应，这种方法不应受到环境协方差和未测量特征的影响。
