Optimal resource allocation to survival and reproduction in parasitic wasps foraging in fragmented habitats

Expansion and intensification of human land use represents the major cause of habitat fragmentation. Such fragmentationcan have dramatic consequences on species richness and trophic interactions within food webs. Although the associatedecological consequences have been studied by several authors, the evolutionary effects on interacting species havereceived little research attention. Using a genetic algorithm, we quantified how habitat fragmentation and environmentalvariability affect the optimal reproductive strategies of parasitic wasps foraging for hosts. As observed in real animal species,the model is based on the existence of a negative trade-off between survival and reproduction resulting from competitiveallocation of resources to either somatic maintenance or egg production. We also asked to what degree plasticity along thistrade-off would be optimal, when plasticity is costly. We found that habitat fragmentation can indeed have strong effectson the reproductive strategies adopted by parasitoids. With increasing habitat fragmentation animals should invest ingreater longevity with lower fecundity; yet, especially in unpredictable environments, some level of phenotypic plasticityshould be selected for. Other consequences in terms of learning ability of foraging animals were also observed. Theevolutionary consequences of these results are discussed