1 July 2009 How to Measure Indirect Genetic Effects: The Congruence of Trait-Based and Variance-Partitioning Approaches
Joel W. McGlothlin, Edmund D. Brodie
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Indirect genetic effects (IGEs), which occur when phenotypic expression in one individual is influenced by genes in another conspecific individual, may have a drastic effect on evolutionary response to selection. General evolutionary models of IGEs have been developed using two distinct theoretical frameworks derived from maternal effects theory. The first framework is trait-based and focuses on how phenotypes are influenced by specific traits in a social partner, with the strength of interactions defined by the matrix Ö. The second framework partitions total genetic variance into components representing direct effects, indirect effects, and the covariance between them, without identifying specific social traits responsible for IGEs. The latter framework has been employed more commonly by empiricists because the methods for estimating variance components are relatively straightforward. Here, we show how these two theoretical frameworks are related to each other and derive equations that can be used to translate between them. This translation leads to a generalized method that can be used to estimate Ψ via standard quantitative genetic breeding designs or pedigrees from natural populations. This method can be used in a very general set of circumstances and is widely applicable to all IGEs, including maternal effects and other interactions among relatives.

© 2009 The Society for the Study of Evolution.
Joel W. McGlothlin and Edmund D. Brodie "How to Measure Indirect Genetic Effects: The Congruence of Trait-Based and Variance-Partitioning Approaches," Evolution 63(7), 1785-1795, (1 July 2009). https://doi.org/10.1111/j.1558-5646.2009.00676.x
Received: 15 December 2008; Accepted: 1 February 2009; Published: 1 July 2009

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animal model
interacting phenotypes
Maternal effects
social evolution
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