Phenotypic and Evolutionary Consequences of Social Behaviours: Interactions among Individuals Affect Direct Genetic Effects

Barbora Trubenová,Reinmar Hager,Yury E Khudyakov

doi:10.1371/journal.pone.0046273

Barbora Trubenová, Reinmar Hager + Show 1 more

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https://doi.org/10.1371/journal.pone.0046273

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Journal: PloS one	Publication Date: Nov 30, 2012
Citations: 8	License type: CC BY 4.0

Affiliation: University of Manchester

Abstract

Traditional quantitative genetics assumes that an individual's phenotype is determined by both genetic and environmental factors. For many animals, part of the environment is social and provided by parents and other interacting partners. When expression of genes in social partners affects trait expression in a focal individual, indirect genetic effects occur. In this study, we explore the effects of indirect genetic effects on the magnitude and range of phenotypic values in a focal individual in a multi-member model analyzing three possible classes of interactions between individuals. We show that social interactions may not only cause indirect genetic effects but can also modify direct genetic effects. Furthermore, we demonstrate that both direct and indirect genetic effects substantially alter the range of phenotypic values, particularly when a focal trait can influence its own expression via interactions with traits in other individuals. We derive a function predicting the relative importance of direct versus indirect genetic effects. Our model reveals that both direct and indirect genetic effects can depend to a large extent on both group size and interaction strength, altering group mean phenotype and variance. This may lead to scenarios where between group variation is much higher than within group variation despite similar underlying genetic properties, potentially affecting the level of selection. Our analysis highlights key properties of indirect genetic effects with important consequences for trait evolution, the level of selection and potentially speciation.

Highlights

Complex social interactions are widespread among animals and are of considerable interest to both behavioural ecologists [1,2,3] and quantitative geneticists [4,5,6]
Understanding the role of interactions among individuals for phenotypic variation and fitness is crucial for the study of such diverse areas as behavioural ecology, where indirect genetic effect (IGE) are implicated in the evolution of cooperation and social dominance [2,7,8,9,10,11] and agriculture [12,13]
As we want to investigate the potential role of social interactions on direct and indirect genetic effects, we will not consider environmental effects other than those caused by social interactions in the following analysis

Summary

Introduction

Complex social interactions are widespread among animals and are of considerable interest to both behavioural ecologists [1,2,3] and quantitative geneticists [4,5,6]. Cooperation, altruism, and aggression and spite are social behaviours, and traits underlying these behaviours are influenced by interactions with conspecifics [15,16,17,18]. Standard quantitative genetics theory assumes that the phenotype, or trait values of an individual, are affected by its genes and the environment. Every individual living in a social environment is affected by the social behaviours of conspecifics, which is partly given by their genotypes. The environment provided by conspecifics is often the most important component of the environment experienced by individuals, frequently having profound effects on trait expression and fitness [19]

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