Nongenetic parental effects can contribute to the adaptation of species to changing environments by circumventing some of the limitations of genetic inheritance. A clearer understanding of the influence of nongenetic inheritance and its potentially sex-specific responses in daughters and sons is needed to better predict the evolutionary trajectories of species. However, whereas nongenetic maternal effects have long been recognized and widely studied, comparatively little is known about corresponding paternal effects. Here, by following 30 isogenic lines of Drosophila melanogaster across two generations, each reared under two dietary regimes in each generation, we tested how protein restriction during larval development of the fathers affects the fitness and health of their daughters and sons. We then quantified genetic and non-genetic paternal, and direct environmental, effects across multiple axes of offspring fitness. Daughters and sons responded differently to their father's developmental history. While isolines differed in mean trait values, their specific responses to protein restriction generally varied little. The sex- and trait-specific responses to paternal effects emphasize the complexity of inter-generational parental effects, which raise important questions about their mode of transmission and adaptive value, including the potential for conflict between the sexes.
Keywords: G×E interaction; intergenerational effects; nongenetic inheritance; paternal effects; sex-specific effects.
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