Abstracts (first author)
Sex specific social genetic effects in parental-care behaviour
The social environment, namely conspecifics, can influence the expression of phenotypes i.e., individuals other than the one expressing the trait in question can explain some of the phenotypic variation. The genetic part of this indirect effect represents an indirect genetic effect (IGE). Not accounting for IGEs can considerably under- or over-estimate the total heritable variation available for selection to act on, and thus predict misleading evolutionary trajectories. Yet, empirical studies on wild populations often ignore IGEs. We present a quantitative genetic analysis of biparental care in a wild, genetically pedigreed, bird population. Sex-specific IGEs increased the total heritable variation. Our data suggests that the female trait could evolve through indirect selection by her mating partner, which most theoretical models explaining the evolution of biparental care do not take into account. Notably, the within-individual repeatability of female parental care was lower than the total heritable variation. Our results show that the assumption that repeatability is the upper limit of heritability should be used cautiously when applying to socially interactive traits, and highlight the importance of accounting for social effects.