The quantitative genetics of indirect genetic effects: a selective review of modelling issues

Abstract

Indirect genetic effects (IGE) occur when the genotype of an individual affects the phenotypic trait value of another conspecific individual. IGEs can have profound effects on both the magnitude and the direction of response to selection. Models of inheritance and response to selection in traits subject to IGEs have been developed within two frameworks; a trait-based framework in which IGEs are specified as a direct consequence of individual trait values, and a variance-component framework in which phenotypic variance is decomposed into a direct and an indirect additive genetic component. This work is a selective review of the quantitative genetics of traits affected by IGEs, with a focus on modelling, estimation and interpretation issues. It includes a discussion on variance-component vs trait-based models of IGEs, a review of issues related to the estimation of IGEs from field data, including the estimation of the interaction coefficient W (psi), and a discussion on the relevance of IGEs for response to selection in cases where the strength of interaction varies among pairs of individuals. An investigation of the trait-based model shows that the interaction coefficient W may deviate considerably from the corresponding regression coefficient when feedback occurs. The increasing research effort devoted to IGEs suggests that they are a widespread phenomenon, probably particularly in natural populations and plants. Further work in this field should considerably broaden our understanding of the quantitative genetics of inheritance and response to selection in relation to the social organisation of populations.

Heterospecific Nest Site Copying Behavior in a Wild Bird: Assessing the Influence of Genetics and Past Experience on a Joint Breeding Phenotype

“…Such non-additive genetic effects arise when (1) the phenotype of a focal individual is affected by interactions with other individuals and (2) this effect is heritable. This defines socalled indirect genetic effects, that are effects of genotypes of other individuals on the phenotype of the focal individual (reviewed by Moore et al, 1997;Bijma, 2014). Among indirect genetic effects are the well-studied maternal effects, i.e., the effects of the mother's genotype on the phenotype of its offspring (McAdam et al, 2014).…”

“…Indirect genetic effects are often overlooked in quantitative genetics studies in the wild, but ignoring these effects can result in over-or under-estimating heritability estimates and can therefore impact predictions about the micro-evolutionary potential of the trait considered (Wolf et al, 1998;Bijma, 2014;McAdam et al, 2014;Wolak and Keller, 2014). Indirect genetic effects may particularly be expected for joint phenotype as they are likely affected by the genotypes of both pair members.…”

Indirect genetic effects in behavioral ecology: does behavior play a special role in evolution?

“…A substantial literature explores the mathematical approaches used to study IGEs. For general overviews see Bleakley et al (2010), McAdam et al (2014); for a treatment of quantitative modeling and parameter estimation issues, see Bijma (2010Bijma ( , 2014.…”

“…IGEs have been documented across a range of additional social traits, including paternal care (Head et al 2012), social dominance (Moore et al 2002;Wilson et al 2011), agonistic encounters (Wilson et al 2009;Santostefano et al 2016), group antipredator behavior (Bleakley et al 2009;Edenbrow et al 2017), and breeding date in birds (Germain et al 2016). In the mosquitofish Gambusia holbrooki, direct genetic effects (DGEs) influence the number of social partners that males of different color morphs encounter, illustrating how DGEs and IGEs can covary (Kraft et al 2016), a critical parameter influencing evolutionary dynamics (Bijma 2014).…”

“…Under such conditions a variance-partitioning approach is informative. Extensive mathematical treatments of IGEs have been published elsewhere, and interested readers are encouraged to consult these resources to learn more about the practicalities of experimental and breeding designs (e.g., Moore et al 1997;Bijma 2010Bijma , 2014Bleakley et al 2009;McGlothlin and Brodie 2009). Here, we focus on parameters of key interest that are accessible to researchers for quantifying the existence, prevalence, magnitude, and potential consequences of IGEs.…”