Dispersal governs the reorganization of ecological networks under environmental change

Abstract

Ecological networks, such as food webs, mutualist webs and host-parasite webs, are reorganizing as species abundances and spatial distributions shift in response to environmental change. Current theoretical expectations for how this reorganization will occur are available for competition or for parts of interaction networks, but these may not extend to more complex networks. Here we use metacommunity theory to develop new expectations for how complex networks will reorganize under environmental change, and show that dispersal is crucial for determining the degree to which networks will retain their composition and structure. When dispersal between habitat patches is low, all types of species interactions act as a strong determinant for whether species can colonize suitable habitats. This colonization resistance drives species turnover, which breaks apart current networks and leads to the formation of new networks. However, when dispersal rates are increased, colonists arrive in high abundance in habitats where they are well adapted, so interactions with resident species contribute less to colonization success. Dispersal ensures that species associations are maintained as they shift in space, so networks retain similar composition and structure. The crucial role of dispersal reinforces the need to manage habitat connectivity to sustain species and interaction diversity into the future.

Molecular characterization of nodule worm in a community of Bornean primates

“…Continuous parasite gene flow between host species suggests a high transmission potential enabled by host movement (Blouin, Yowell, Courtney, & Dame, ). From a metapopulation perspective, the dispersal abilities of parasite species through host movement play a key role in parasite local adaptation and the resilience of host–parasite associations to habitat disturbance, providing a buffer against local parasite extinctions (Gandon & Michalakis, ; Legrand et al, ; Thompson & Gonzalez, ). Finally, although our sampling and analyses did not include the human population, we do not discard the possibility of O. aculeatum having a zoonotic potential in the same fashion that O. bifurcum and O. stephanostomum do.…”

Towards a multi‐trophic extension of metacommunity ecology

“…). Despite the fact that we know that trophic level is a key predictor of how species will respond to such changes, we have limited theory that links this response to movement within a food web context (but see Thompson & Gonzalez ). Theoretical models offer the opportunity for developing expectations of how different patterns of spatial use properties affect the response of food webs to different forms of environmental change or habitat loss.…”

Spatial insurance in multi‐trophic metacommunities

“…For example, environmental change can alter the strength of top‐down vs. bottom‐up effects (Kratina et al ), the flux of biomass through food webs (Ledger et al ), and the shape of biomass pyramids (O'Connor et al ; de Sassi & Tylianakis ). Metacommunity theory predicts that dispersal, by maintaining species diversity, can maintain food web properties such as number of interactions per species and number of trophic levels (Thompson & Gonzalez ). However, maintenance of food web structure may be contingent on whether immigrating species perform the same functions as the species they replace.…”