Data from: Modelling the co-evolution of indirect genetic effects and inherited variability

When individuals interact, their phenotypes may be affected by genes in their social partners, a phenomenon known as Indirect Genetic Effects (IGEs). In aquaculture species and some plants, competition not only affects trait levels of individuals, but also inflates variation of trait values among individuals. Variability of trait values has been studied as a quantitative trait in itself, and is often referred to as inherited variability. Although the observed phenotypic relationship between competition and variability suggests an underlying genetic relationship, models of IGE and inherited variability do not allow for such relationship. Models of trait levels show IGEs may considerably change heritable variation in trait values. Currently, we lack the tools to investigate whether this result extends to inherited variability. Here we present a model that integrates IGEs and inherited variability. In this model, the target phenotype, say growth rate, is a function of genetic and environmental effects of the focal individual and of the difference in trait values between the social partner and the focal individual, multiplied by a regression coefficient. The regression coefficient is a genetic trait which is measure of cooperation; a negative value indicates competition, a positive value cooperation, and an increasing value due to selection indicates the evolution of cooperation. Our simulations show that the model results in increased variability of body weight with increase of competition. When competition decreases, variability becomes significantly smaller. Our findings suggest we may have been overlooking an entire level of genetic variation in variability, the one due to IGEs.当个体发生社交互动时，其表型可能会受到社交伙伴体内基因的影响，这一现象被称为间接遗传效应（Indirect Genetic Effects，IGEs）。在水产养殖物种与部分植物类群中，种间竞争不仅会影响个体的性状水平，还会放大个体间的性状值变异。性状值的变异本身已被作为一类数量性状开展研究，通常被称为遗传变异度（inherited variability）。尽管观测到的竞争与变异间的表型关联暗示了潜在的遗传关联，但现有的间接遗传效应模型与遗传变异度模型均未纳入这类关联的考量。针对性状水平的相关模型显示，间接遗传效应可能会极大地改变性状值的可遗传变异。目前，学界尚缺乏相关工具以探究这一结论是否可延伸至遗传变异度领域。本研究提出了一款整合间接遗传效应与遗传变异度的模型。在该模型中，目标表型（例如生长速率）是焦点个体自身的遗传与环境效应，以及社交伙伴与焦点个体间的性状值差值与回归系数乘积的函数。该回归系数是一类表征合作程度的遗传性状：负值对应竞争，正值对应合作，而经选择后该系数的递增则预示着合作行为的演化。我们的模拟实验结果显示，随着竞争程度加剧，该模型会导致体重的变异程度升高；而当竞争程度降低时，体重的变异程度则会显著下降。本研究的结果表明，我们此前可能忽略了一类由间接遗传效应引发的、全新的遗传变异层级——即性状变异自身的遗传变异维度。