The evolution of lifespan and ageing in response to dietary macronutrients in male and female decorated crickets

Dietary macronutrients regulate lifespan and ageing, yet little is known
about their evolutionary effects. Here, we examine the evolutionary
response of these traits in decorated crickets (Gryllodes sigillatus)
maintained on diets varying in caloric content and protein-to-carbohydrate
ratio. After 37 generations, each population was split: half remained on
the evolution diet and half switched to a standardized diet. Crickets
lived longer and aged slower when evolving on high-calorie (both sexes)
and carbohydrate-biased (females only) diets and had lower baseline
mortality on high-calorie (females only) diets. However, on the
standardized diet, crickets lived longer when evolving on high-calorie
diets (both sexes), aged slower on high-calorie (females only) and
carbohydrate-biased (both sexes) diets, and had lower baseline mortality
on high-calorie (males only) and protein-biased (both sexes) diets.
Lifespan was longer and baseline mortality lower when provided the
evolution versus the standardized diet but ageing rate was comparable.
Moreover, lifespan was longer, ageing slower (females only) and baseline
mortality lower (males only) compared to our evolved baseline suggesting
varying degrees of dietary adaptation. Collectively, we show dietary
components influence the evolution of lifespan and ageing in different
ways and highlight the value of combining experimental evolution with
nutritional geometry.