Non-random food-web assembly at habitat edges increases connectivity and functional redundancy

Authors: PERALTA, GUADALUPE - Canterbury Christchurch College; FROST, CAROL - Canterbury Christchurch College; DIDHAM, RAPHAEL - Agricultural University Of Western Australia; Rand, Tatyana; TYLIANAKIS, JASON - Canterbury Christchurch College

Submitted to: Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2016
Publication Date: 4/1/2017
Publication URL: https://handle.nal.usda.gov/10113/5695436
Citation: Peralta, G., Frost, C.M., Didham, R.K., Rand, T.A., Tylianakis, J.M. 2017. Non-random food-web assembly at habitat edges increases connectivity and functional redundancy. Ecology. 98(4):995–1005. doi:10.1002/ecy.1656.

Interpretive Summary: Habitat fragmentation dramatically alters the way different habitats are laid out across the landscape, with the creation of new edges between human landuses, such as crop fields, and natural habitats. Edge associated landscape changes can have strong effects on which species are present within a community, as well as the interactions between them. Despite this, exactly how different food-webs in adjacent habitats merge at edges, and what the consequences might be for community stability and resilience, remains unknown. Here we examined whether the composition and structure of herbivore-parasitoid food webs at edges between native and plantation forests could be predicted from those of these two adjacent habitat types. We found that habitat edges did not mark a clear division in food-web composition between forest types, nor did edge food-web structure arise through a random sampling of interactions from the adjacent habitats. Instead, food-web assembly at edges was driven by shifts in the composition of parasitoids communities and changes in their interactions across habitats. The increase in edges associated with conversion of habitat for human use may thus results in novel edge food webs, that are potentially less stable than webs in either adjacent habitats.

Technical Abstract: Habitat fragmentation dramatically alters the spatial configuration of landscapes, with the creation of artificial edges affecting community structure and species interactions. Despite this, it is not known how the different food-webs in adjacent habitats merge at their boundaries, and what the consequences might be for community assembly. Here we examined whether the composition and structure of herbivore-parasitoid food webs across edges between native and plantation forests could be predicted from those of the adjacent communities. We found that habitat edges did not mark a clear division in food-web composition between forest types, nor did edge food-web structure arise through a random sample of interactions from their adjacent habitats. Instead, food-web assembly at edges was driven by discontinuities in species composition and rewiring of interactions across habitats. Proliferation of habitat edges following land-use change may increase the frequency of communities with lower stability.