The role of social effects in selection for animal improvement

• Main Author: Jason B. Wolf
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Zootecnia 2008-07-01
• Series: Revista Brasileira de Zootecnia
• Subjects: associate effects; group selection; indirect genetic effects; social effects; social environment
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982008001300017
• ISSN: 1516-3598; 1806-9290

Quantitative genetics can be used to understand how traits will respond to artificial selection regimes, and therefore, it can be an important tool in the development of selective breeding programs for animal improvement. In order to predict the response to selection, the traditional approach in quantitative genetics partitions phenotypic variation into a heritable genetic component that contributes to the response and a non-heritable environmental component that does not. However, there is an increasing recognition that environmental variation contributed by the social environment provided by conspecifics can ultimately originate from genetically heritably traits in a population of interacting individuals, blurring the distinction between genetic and environmental variation. The presence of these 'social effects' on trait expression means the environment can provide a source of heritable variation that can contribute to trait evolution. Under some conditions, such as when there is competition, the social effects of genotypes on the phenotypes of other individuals may oppose their direct effects on their own phenotypes and, as a result, the evolution of social effects can oppose the evolution of direct genetic effects and thereby can impede the response to selection. Furthermore, when the social effects of genotypes are uncorrelated with their direct effect, the heritable variance contributed by social effects will not contribute to a response to selection on individuals, meaning that a major part of the genetic variance in a population can be unavailable to selective breeding. These constraints can be overcome by using populations of related individuals or through group selection approaches that allow for the social effects to contribute to a response to selection.