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The population-dynamic consequences of feeding on multiple prey at a time.

The population-dynamic consequences of feeding on multiple prey at a time.

Start: Friday, May 26, 2023 10:00 am
End: Friday, May 26, 2023 11:00 am

Mark Novak

Oregon State University

There is a common belief among empirically-minded ecologists that the linear and rectilinear forms of the Holling type I functional response are an unrealistic and artifactual way of characterizing predator feeding rates. Thus, despite being a cornerstone of dynamical models in population and community ecology, the type I model is typically dismissed a priori from both empirical and theoretical efforts to mechanistically characterize predator feeding rates. Here, my goal will be to consider a mechanism for functional responses to exhibit linear prey dependence that has received only scant attention in the literature: the ability of predator individuals to handle, search for and capture more than just one prey individual at a time ("multi-prey" feeding). I will (1) discuss the interpretation of handling times as it relates to the presumed exclusivity of searching and handling, (2) provide a derivation of a multi-prey functional response to evidence the emergence of Holling's linear and rectilinear type I forms from Holling's type II disc equation without the difficult-to-justify assumption that handling times are negligibly short, and (3) incorporate it into the foundational ``paradox of enrichment'' population-dynamic model to assess the influence of multi-prey feeding on the stability of predator-prey interactions. My analyses demonstrate that small increases in the number of prey that a predator can handle at a time can lead to qualitatively different coexistence and dynamical outcomes. These altered outcomes include the appearance of long-term, many-generation transient dynamics and a partial resolution to the paradox of enrichment.

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