Adaptation to developmental diet influences the response to selection on age at reproduction in the fruit fly

Abstract

Experimental evolution (EE) is a powerful tool for addressing how environmental factors influence life‐history evolution. While in nature different selection pressures experienced across the lifespan shape life histories, EE studies typically apply selection pressures one at a time. Here, we assess the consequences of adaptation to three different developmental diets in combination with classical selection for early or late reproduction in the fruit fly Drosophila melanogaster. We find that the response to each selection pressure is similar to that observed when they are applied independently, but the overall magnitude of the response depends on the selection regime experienced in the other life stage. For example, adaptation to increased age at reproduction increased lifespan across all diets; however, the extent of the increase was dependent on the dietary selection regime. Similarly, adaptation to a lower calorie developmental diet led to faster development and decreased adult weight, but the magnitude of the response was dependent on the age‐at‐reproduction selection regime. Given that multiple selection pressures are prevalent in nature, our findings suggest that trade‐offs should be considered not only among traits within an organism, but also among adaptive responses to different—sometimes conflicting—selection pressures, including across life stages.

Distinct genomic signals of lifespan and life history evolution in response to postponed reproduction and larval diet inDrosophila

“…The setup of the EE study is described in detail in May et al. (). In short, to maximize the amount of standing genetic variation on which selection could act, the EE base population was generated by combining flies from six populations collected across Europe that had been maintained in the laboratory for 40 generations (May et al.…”

“…Life history phenotypes (lifespan, development time, fecundity, and adult weight) were measured after multiple intervals of selection (May et al. ).…”

“…These observations suggest that the two selective regimes could act relatively independent of each other (May et al. ). However, the magnitude of the lifespan and life history responses to each selective regime did depend on the other regime.…”

“…To address these questions, we studied a set of 24 experimental evolution (EE) populations of D. melanogaster that diverged in lifespan and life history in response to a factorial combination of two selection regimes: developmental diet (“low” [L], “control” [C], or “high” [H] diet) and reproductive age (“early” [E] vs. “postponed” [P] reproduction), that is, six regime combinations with four replicate populations each (May et al. ; Fig. ).…”

“…Also the decrease in development time and adult weight on the “low” diet was most pronounced for early reproducing populations (May et al. ). This indicated that the two selection regimes also interacted in affecting the evolution of lifespan and correlated traits.…”