Synthesizing habitat fragmentation effects on plant-antagonist interactions in a phylogenetic context

Abstract

Plant-antagonist interactions shape the structure, composition and dynamics of plant communities and ecosystems. Due to their key importance, much research has been advocated to evaluate anthropogenic habitat loss and fragmentation effects on plant-antagonist interactions but no clear response patterns have arisen. Even recent quantitative reviews have failed to provide consistent generalizations. Here we conduct the first phylogenetically independent meta-analysis along with a traditional meta-analytical approach. We examined whether characteristics of the interaction, the fragmented landscape, and methodological approaches modulate the magnitude of effects. Traditional meta-analysis showed that plants within habitat fragments suffer on average less damage from antagonists. However, when incorporating the phylogenetic relationships among plants, the overall effect and the particular effects of moderators became non-significant. Interestingly, we found a strong and consistent trend between both meta-analytical approaches in the overall effect of habitat fragmentation on folivory elicited by insects. This implies the first genuine fragmentation effect that transcends the phylogeny of plants and is not undermined by statistical problems of pseudoreplication. Decreased insect folivory will favor certain plant species, especially those with acquisitive resource use traits such as pioneer and exotic invasive, thereby affecting plant community composition in fragmented habitats. Here, we highlight the importance of incorporating the phylogeny in meta-analytical contexts. Our results imply that current studies worldwide represent a phylogenetically-conserved sample of fragmentation effects on plant-antagonist interactions. Thus, more studies on distantly phylogenetically-related plants are needed to have a broader, more representative, sample of responses across angiosperms.