The response of life-history traits to a new species in the community: A story of Drosophila parasitoids from the Rhône and Saône valleys

Abstract

In the present study, we investigated the evolution of life-history traits in the main species of a community, after the arrival of a new competitor. Two parasitoid species, Leptopilina heterotoma and Asobara tabida, are present throughout the Rhône and Saône valleys, whereas a third species, Leptopilina boulardi, is slowly extending its distribution northwards. In the presence of L.boulardi, competing parasitoids experience a higher mortality and lower host availability. Resources should thus be re-allocated between traits according to these new factors. We compared life-history traits of populations of L.heterotoma and A.tabida in areas with and without L.boulardi. As predicted by both Price's balanced mortality hypothesis and the theory of life-history traits, we found that investment in reproduction is higher in southern populations for both native species, coupled with higher travelling abilities. However, only A.tabida paid their higher fecundity by a lower longevity. The absence of a clear trade-off between these traits in L.heterotoma may be explained by a lower metabolic rate in southern populations. These results highlight the importance of the community change over climate in the evolution of life-history traits in this parasitoid community. © 2012 The Linnean Society of London.