Abstract:
Ecological communities are often characterised by many species occupying the same trophic level
and competing over a small number of vital resources. The mechanisms maintaining high biodiversity
in such systems are still poorly understood. Here, we revisit the role of prey selectivity by
generalist predators in promoting biodiversity. We consider a generic tri-trophic food web, consisting
of a single limiting resource, a large number of primary producers and a generalist predator.
We suggest a framework to describe the predator functional response, combining food
selectivity for distinctly different functional prey groups with proportion-based consumption of
similar prey species. Our simulations reveal that intermediate levels of prey selectivity can explain
a high species richness, functional biodiversity, and variability among prey species. In contrast,
perfect food selectivity or purely proportion-based food consumption leads to a collapse of prey
functional biodiversity. Our results are in agreement with empirical phytoplankton rank-abundance
curves in lakes.
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