Diet-induced plasticity of life-history traits and gene expression in outbred Drosophila melanogaster population

Food is fundamental for the survival of organisms, governing growth,
maintenance, and reproduction through the provision of essential
macronutrients. However, access to food with optimum macronutrient
composition, which will maximize the evolutionary fitness of an organism,
is not always guaranteed. This leads to dietary mismatches with potential
impacts on organismal performance. To understand the consequences of such
dietary mismatches, we examined the effects of isocaloric diets varying in
macronutrient composition on eight key organismal traits spanning across
the lifespan of a large outbred Drosophila melanogaster population (n ~
2500). Our findings reveal that carbohydrate-reduced isocaloric diets
correlates to accelerated pre-adult development and boosts reproductive
output without impacting pre-adult viability and body size. Conversely, an
elevated dietary carbohydrate content correlated to reduced lifespan in
flies, evidenced by accelerated functional senescence including
compromised locomotor activity and deteriorating gut integrity.
Furthermore, transcriptomic analysis indicated a substantial difference in
gene regulatory landscapes between flies subject to high carbohydrate vs
high protein diet, with elevated protein levels indicating transcriptomes
primed for reduced synthesis of fatty acids. Taken together, our study
helps advance our understanding of the effect of macronutrient composition
on life history traits and their interrelations, offering critical
insights into potential adaptive strategies that organisms might adopt
against the continual dietary imbalances prevalent in the rapidly evolving
environment.