Transgenerational effects of diet environment on life-history and acoustic signals of a grasshopper

Phenotypic plasticity can be due to environmental conditions experienced during an individual’s lifetime, but can also be based on parental effects, that is the responses of the parental generation to their own environment. Such transgenerational responses might be adaptive by allowing fine-tuning of offspring traits to the present environment. We examined whether the parental and offspring diet affect offspring life history and sexually selected acoustic signal traits in the grasshopper Chorthippus biguttulus. In a full factorial design, parents and offspring were reared on high-quality or poor-quality diet. We found significant positive effects of parental high-quality food on offspring developmental time, body mass, song amplitude in adult males, and weight of egg pods in adult females. In all cases, these effects were larger than direct effects of the diet environment experienced during ontogeny, even though some of these were significant, too. Interactions between parental and ontogenetic treatments were all nonsignificant, indicating that offspring traits are not adjusted to enhance performance on the same diet as the parent. We conclude that parental effects are unexpectedly stronger than effects of the offspring diet environment in C. biguttulus. These parental effects do not seem to constitute adaptive phenotypic plasticity, but nevertheless show that the nutritional environment of the parents has a large influence on traits in C. biguttulus grasshoppers.