Life history and behavioral responses to time constraints in a damselfly

Time constraints, imposed by seasonality, are common to life histories. Rec ent theory in evolutionary ecology predicts independent behavioral and life history responses to such constraints, but this theory remains largely unt ested. In our two experiments on the damselfly Lestes congener we experimen tally alter individual's perception of their proximity to a time constraint and ask whether their behavior and life history respond in the directions predicted by theory. We altered larval perception of their position in the season with light regime. In one group, we hatched larvae from winter diapa using eggs in a light regime that mimics a relatively early time in the sea son. In the other group we hatched larvae in a light regime that mimics a l ate time in the season. In the late (time constrained) group, larvae would have very little time to complete development and reach a large size so tha t they could attain their full reproductive potential prior to winter. In t he first experiment, the behaviors we assess are activity rate, which is an indicator of foraging effort and willingness to take risks, and cannibalis m, which is a component of the mortality risk of foraging. As predicted, ti me-constrained larvae increased their activity rates, perhaps in an attempt to increase weight gain, and as a result they suffered higher rates of can nibalism. In the second experiment, we measured development rate as the rat e of molting and age at maturity. As predicted, time-constrained larvae acc elerated development rate and thereby matured at a significantly earlier ag e and smaller size. Our analysis demonstrates that the behavioral and life history responses of these larvae were independent, in the sense that the l ife history responses did not result from the behavioral responses.