Weighting and indirect effects identify keystone species in food webs
Academic Article
Overview
Overview
Abstract
Species extinctions are accelerating globally, yet the maintenance of local biodiversity in natural food webs remains poorly understood. ‘Hub’ species, which have many direct connections within food webs, have been traditionally regarded as facilitating community persistence, yet the importance of link weights based on material flow and indirect effects has been largely ignored. Here, we used a dynamical model based on empirical energy-budget data to simulate cascading extinctions for deletion orders considering weighted versus unweighted links, with and without indirect effects. Sequential deletion of taxa considering the magnitudes of link weight and/or indirect effects caused increased secondary extinctions and reduced food web stability more strongly than the removal of ‘hubs’. These results were robust to considering both linear and non-linear functional responses in our dynamical model and to the values chosen for the free parameters in our model. Thus, we demonstrate that both quantitative fluxes and species that dissipate their effects across many nodes should be of great concern in biodiversity conservation, and the potential for hubs to act as keystone species may have been exaggerated to date.
