Canario L, Lundeheim N, Bijma P
Department of Animal Genetics, INRA French National Institute for Agricultural Research, Castanet-Tolosan, France.
Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Heredity (Edinb). 2017 Jun;118(6):534-541. doi: 10.1038/hdy.2017.3. Epub 2017 Mar 22.
Social interactions among individuals are abundant, both in natural and domestic populations, and may affect phenotypes of individuals. Recent research has demonstrated that the social effect of an individual on the phenotype of its social partners may have a genetic component, known as an indirect genetic effect (IGE). Little is known, however, of nongenetic factors underlying such social effects. Early-life environments often have large effects on phenotypes of the individuals themselves later in life. Offspring development in many mammalian species, for example, depends on interactions with the mother and siblings. In domestic pigs, individuals sharing the same juvenile environment develop similar body weight later in life. We, therefore, hypothesized that offspring originating from the same early-life environment also develop common social skills that generate early-life social effects (ELSEs) that affect the phenotypes of their social partners later in life. We, therefore, quantified IGEs and ELSEs on growth in domestic pigs. Results show that individuals from the same early-life environment express similar social effects on the growth of their social partners, and that such ELSEs shape the growth rate of social partners more than IGEs. Thus, the social skills that individuals develop in early life have a long-lasting impact on the phenotypes of social partners. Early-life and genetic social effects were independent of the corresponding direct effects of offspring on their own growth, indicating that individuals may enhance the growth of their social partners without a personal cost. Our findings also illustrate how research devoted to quantifying IGEs may miss nongenetic and potentially confounded social mechanisms which may bias the estimates of IGEs.
个体之间的社会互动在自然种群和家养种群中都很丰富，并且可能影响个体的表型。最近的研究表明，个体对其社会伙伴表型的社会效应可能具有遗传成分，即间接遗传效应（IGE）。然而，对于这种社会效应背后的非遗传因素知之甚少。早期生活环境通常对个体后期的表型有很大影响。例如，许多哺乳动物物种的后代发育依赖于与母亲和兄弟姐妹的互动。在家养猪中，共享相同幼年环境的个体在后期生活中体重增长相似。因此，我们假设来自相同早期生活环境的后代也会发展出共同的社交技能，从而产生影响其社会伙伴后期表型的早期生活社会效应（ELSE）。因此，我们对家猪生长中的IGE和ELSE进行了量化。结果表明，来自相同早期生活环境的个体对其社会伙伴的生长表现出相似的社会效应，并且这种ELSE对社会伙伴生长速率的塑造作用大于IGE。因此，个体在早期生活中发展的社交技能对社会伙伴的表型有持久影响。早期生活和遗传社会效应独立于后代自身生长的相应直接效应，这表明个体可能在不付出自身代价的情况下促进其社会伙伴的生长。我们的研究结果还说明了致力于量化IGE的研究可能如何忽略非遗传且可能混淆的社会机制，这些机制可能会使IGE的估计产生偏差。
