Age-related shifts in dietary and oviposition preferences and steep costs of modest parental ageing in Drosophila melanogaster

Oonagh Barker, Tracey Chapman, Alexei A. Maklakov, Edward Ivimey-Cook, Wilfried Haerty

Nutritional requirements vary across sexes and throughout an organism’s lifetime, and are predicted to influence dietary preferences to maximise fitness. However, the consequences of age-related changes in dietary preferences within and across generations are unknown. This is an important omission, as age-related changes in nutrient intake could have direct, sex-specific effects on offspring. We addressed this using the fruitfly Drosophila melanogaster to measure age-specific choice among three protein:carbohydrate (P:C) diets in both sexes. Simultaneously, we measured age-specific oviposition site choices and tracked offspring development, survival and dietary preferences. Older females showed stronger preferences for protein than younger females, and older males spent less time on balanced and high protein diets than younger males. Females preferred to oviposit on balanced P:C, however preference for high carbohydrate increased with age. Third instar larvae of older parents preferred balanced P:C, while larvae of younger parents showed no overall preference. Unexpectedly, offspring of 15-day-old parents showed slower development and higher preadult mortality than those of 5-day-old parents, revealing novel effects of only a modest increase in parental age. These findings highlight interdependence between reproductive ageing and nutrient selection, and suggest an underappreciated interaction between parental age and early nutrition in shaping offspring life history.