A longstanding question in community ecology is what makes for a stable community. The study of food webs has sought to answer this question by assessing how different food web architectures impact community stability. Food web structure not only impacts the dynamics of the community, the population dynamics in the community in turn alter food web structure. Structure may change as a result of altered interactions through prey switching or through the local extinction/invasion of participating species. Previous work has suggested that some food web structures (e.g., short trophic chains, and motifs) are so commonly observed because they are more likely to be stable and thus less likely to be lost via extinction of participating species. I seek to determine how commonly observed food web structures change as a result of species loss and introduction. To answer this question I simulated dynamics for model food webs following species removals and introductions to determine the effect of cahnges in topological structure on the stability of the community.
Results/Conclusions
I assess how species deletions and introductions alter food web structure and determine how those changes affect either the persistence of the web or the success of the invasion using principle components regression. I found substantial variation in the results affected by the model structure and parameterization. Some generalities included significant effects of individual species’ properties on the outcome, as well as variable but significant effects of the change in the motif profile for both persistence following deletion and invasion success. Thus while there is support for some selection on stability process leading to observed patterns in the number of trophic levels, there is a more complicated story for three species motifs.