Disentangling genetic and prenatal sources of familial resemblance across ontogeny in a wild passerine.

Cross-fostering experiments are widely used by quantitative geneticists to study genetics and by behavioral ecologists to study the effects of prenatal in- vestment. Generally, the effects of genes and prenatal investment are confounded and the interpretation given to such experiments is largely dependent on the in- terests of the researcher. Using a large-scale well controlled experiment on a wild population of blue tits (Cyanistes caeruleus) we are able to partition variation in body mass across ontogeny into the effects of genes and the effects of between- clutch variation in egg characteristics. We show that although egg effects are important early in ontogeny they quickly dissipate, suggesting that the genetic interpretation of cross-fostering experiments may be preferable for many types of trait. However, the heritability of body mass is smaller than has previously been reported. Our results suggest that this is due to a combination of control- ling postnatal environmental effects more carefully and accounting for viability selection operating early in ontogeny.

交叉抚育实验（cross-fostering experiments）被数量遗传学家广泛用于遗传学研究，同时也被行为生态学家用以探究产前投入的效应。通常而言，基因效应与产前投入效应往往存在混淆，对这类实验的解读很大程度上取决于研究者的研究侧重。本研究基于对野生蓝山雀（Cyanistes caeruleus）种群开展的大规模严格对照实验，将个体发育（ontogeny）全过程中的体重变异分解为两大来源：基因效应，以及不同窝次间卵性状差异带来的效应。研究结果表明，尽管卵相关效应在个体发育早期较为显著，但会快速消退，这表明针对多数性状，采用遗传学视角解读交叉抚育实验或许更为合理。不过，本次研究测得的体重遗传力（heritability）低于既往报道的水平。我们的分析显示，这一现象源于两方面因素的共同作用：一是对产后环境效应的控制更为严谨，二是纳入了个体发育早期发挥作用的存活性选择。