Dietary Zinc Limitation Dictates Lifespan and Reproduction Trade-Offs of Drosophila Mothers.

Dietary metal ions significantly influence the lifespan and reproduction of Drosophila females. In this study, we show that not adding any of the metal ions to the diet adversely affects reproduction and lifespan. By contrast, food with no added Zn negatively impacts reproduction but does not adversely affect maternal lifespan, indicating it can dictate resource reallocation between key fitness traits. Specifically, it indicates that female flies stop producing eggs to conserve their body Zn for somatic maintenance. Although these data show that flies can sense varying dietary Zn levels to adjust their physiology, they cannot maximise egg production when faced with a choice between food with no added Zn or food with sufficient Zn to support maximum reproduction. Nonetheless, they can choose to preferentially oviposit on Zn-containing food, perhaps indicating a strategy to assure offspring survival. We also uncovered a role for the white gene in sustaining high levels of egg viability when Zn is diluted in the diet. These insights into the role of dietary metal ions, particularly Zn, point to a central role for these dietary micronutrients to indicate environmental quality and so govern trade-offs between lifespan and reproduction in flies.