Animal Breeding and Genomics Centre, Wageningen University Wageningen, Netherlands.
Behavioural Ecology Group, Wageningen University Wageningen, Netherlands.
Front Genet. 2014 Nov 11;5:377. doi: 10.3389/fgene.2014.00377. eCollection 2014.
Social interactions between individuals living in a group can have both positive and negative effects on welfare, productivity, and health of these individuals. Negative effects of social interactions in livestock are easier to observe than positive effects. For example, laying hens may develop feather pecking, which can cause mortality due to cannibalism, and pigs may develop tail biting or excessive aggression. Several studies have shown that social interactions affect the genetic variation in a trait. Genetic improvement of socially-affected traits, however, has proven to be difficult until relatively recently. The use of classical selection methods, like individual selection, may result in selection responses opposite to expected, because these methods neglect the effect of an individual on its group mates (social genetic effects). It has become clear that improvement of socially-affected traits requires selection methods that take into account not only the direct effect of an individual on its own phenotype but also the social genetic effects, also known as indirect genetic effects, of an individual on the phenotypes of its group mates. Here, we review the theoretical and empirical work on social genetic effects, with a focus on livestock. First, we present the theory of social genetic effects. Subsequently, we evaluate the evidence for social genetic effects in livestock and other species, by reviewing estimates of genetic parameters for direct and social genetic effects. Then we describe the results of different selection experiments. Finally, we discuss issues concerning the implementation of social genetic effects in livestock breeding programs. This review demonstrates that selection for socially-affected traits, using methods that target both the direct and social genetic effects, is a promising, but sometimes difficult to use in practice, tool to simultaneously improve production and welfare in livestock.
个体之间的社会互动对这些个体的福利、生产力和健康可能产生积极和消极的影响。与积极影响相比，家畜社会互动的负面影响更容易观察到。例如，蛋鸡可能会出现啄癖，这可能会导致因同类相食而死亡，而猪可能会出现咬尾或过度攻击。一些研究表明，社会互动会影响一个特征的遗传变异。然而，直到最近，具有社会影响的特征的遗传改良才被证明是困难的。使用经典的选择方法，如个体选择，可能会导致与预期相反的选择反应，因为这些方法忽略了个体对其群体成员的影响（社会遗传效应）。很明显，要改善具有社会影响的特征，需要选择方法不仅要考虑个体对自身表型的直接影响，还要考虑个体对其群体成员表型的社会遗传效应，也称为间接遗传效应。在这里，我们回顾了关于社会遗传效应的理论和实证工作，重点是家畜。首先，我们介绍了社会遗传效应的理论。随后，我们通过评估直接和社会遗传效应的遗传参数估计值，评估了家畜和其他物种中社会遗传效应的证据。然后我们描述了不同选择实验的结果。最后，我们讨论了在家畜育种计划中实施社会遗传效应的问题。这篇综述表明，使用既针对直接遗传效应又针对社会遗传效应的方法来选择具有社会影响的特征，是一种很有前途的工具，但在实践中有时难以使用，可以同时提高家畜的生产和福利。
