Abstract
Overexploitation can lead to a rapid collapse of consumers that is difficult to reverse if ecosystems exhibit alternative stable states. However, support for this phenomenon remains predominantly limited to simple models, whereas food webs might dissipate the feedback loops that create alternative stable states through species-specific demography and interactions. Here we develop a general model of consumer-resource interactions with two types of processes: either specialized feedbacks where individual resources become unpalatable at high abundance or aggregate feedbacks where overall resource abundance reduces consumer recruitment. We then quantify how the degree of interconnectedness and species differences in demography affect the potential for either feedback to produce consumer- or resource-dominated food web states. Our results highlight that such alternative stable states could be more likely to happen when aggregate feedbacks or lower species differences increase redundancy in species contributions to persistence of the consumer guild. Conversely, specialized palatability feedbacks with distinctive species roles in guild persistence reduce the potential for alternative states but increase the likelihood that losing vulnerable consumers cascades into a food web collapse at low stress levels, a fragility absent in few-species models. Altogether, we suggest that species heterogeneity has a greater impact on whether feedbacks prevent consumer recovery than on the presence of many-species collapses.
Competing Interest Statement
The authors have declared no competing interest.