Functional responses can’t unify invasion ecology
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Dick et al. (Biol Invasions, 2017) propose that the comparative functional response framework provides a unifying approach for the study of invasive species. We agree that functional responses are an important and powerful quantitative description of consumer effects on resources, and co-opting classical ecological theory to better predict invasive species impacts is a laudable move for invasion biology. However, we fear that the early successes of select examples of the comparative functional response (CFR) approach has led Dick et al. to exaggerate the generality of its utility, and about its ability to unify the field. Further, they fail to provide a convincing argument why CFR is better than existing tools such as invasion history or impact indices, even when considering emerging or potential invaders. In this response we provide details of three conceptual issues stemming from classical ecological theoretical frameworks and two practical problems that Dick et al. and other CFR proponents need to address.
KeywordsFunctional responses Impact prediction Impact indices Resource–consumer Prey–predator Invasion hypotheses
We gratefully acknowledge the support of the DST-NRF Centre of Excellence for Invasion Biology, for a CIB fellowship to MM, hosting JV, funding JM and for facilitating a workshop on Functional Responses in Invasion Biology at Stellenbosch University, South Africa, in November 2015. In addition, we thank Jaimie Dick and colleagues for their stimulating Flashpoint.
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