Tara-Lyn Camilleri, Matthew D.W. Piper, Rebecca L. Robker, Damian K. Dowling
This is a plain language summary of a Functional Ecology research article which is published here.
We altered the diets of fruit fly parents to observe how diet alters the fitness of parents and their offspring. Evidence so far demonstrates that when the diet of the parent is altered, effects are passed from parent to offspring—beyond the transfer of genes alone. It remains unknown, however, whether diets that are optimal for parents are likewise optimal for their offspring. Traditional theory suggests an advantage for offspring if they have an environment that matches their parents, but evidence for this concept so far is mixed. If we expect that offspring that have a diet that matches their parents might live longer or have higher reproductive success, will that be true for all diet combinations? Furthermore, it remains unclear which parent passes on the strongest effects (especially since most studies don’t consider both parents). We sought to answer these questions by challenging both the parents and both sexes of offspring with a diet of either higher or lower sucrose, so that we could observe the effects of all possible combinations of diets represented in our study.
We found no evidence that offspring lived longer if they ate a diet that matched one or more of their parents. Instead, we found that if the diets of the parents matched (i.e. female and male both ate either high or low sucrose), then each parent lived longer than if the parental diets were mismatched. Offspring from these “matched” parental combinations, however, did not live as long as offspring from combinations where parental diets were mismatched. This highlights to us that a diet combination optimal for parents may not actually be optimal for their offspring. Similarly, we found that more eggs were produced by the daughters of parents who ate mismatched diet combinations.
Future studies should investigate whether these effects are consistently transmitted across further generations, and whether they are specific to the dietary conditions (sucrose manipulation) used in our study, or extend more broadly across other contexts such as protein modification. Our work highlights the need for future studies to consider both maternal and paternal effects together if we hope to understand how the interaction between the two affects the health and fitness of subsequent generations.