Predators that benefit prey and prey that harm predators: unusual effects of interacting foraging adaptations

Article Abstract:

Models of four-trophic-level food webs were studied to determine how the adaptive balancing of food intake with risk of predation in two or more species affects the food chain. It was shown that adaptive foraging behaviors reach a stable equilibrium. Differential equations of population dynamics based on this stable equilibrium were very different from Lotka-Volterra food web models. Increased predator density could increase prey fitness, while increased prey density could reduce predator fitness. Each species affects the per capita growth rate of every other species in the food web, and the effects may be larger the more distant a species is in the food web.

Food chains (Ecology), Food chains

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Overestimation versus underestimation of predation risk: a reply to Bouskila et al

Article Abstract:

There is no substantial proof that overestimation is preferable to underestimation for most animal fitness functions. This is due to the scarcity of relationship studies on foraging strategies. Suggestions of overestimation cannot be properly supported due to limited information on whether animals underestimate or overestimate risk. On the other hand, the deterministic model is the best way to understand stochastic models instead of a stochastic model that adopts the wrong type of stochasticity.

Evaluation, Stochastic processes, Predator hunting

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Limits to the similarity of competitors under hierarchical lottery competition

Article Abstract:

S.W. Pacala and D. Tilman's series of hierarchical lottery competition models between plants demonstrates that there is a bounded restriction to the similarity of rival species. Too many similarities between species will result in at least one being driven to extinction. However, an analysis of their models reveals a misinterpretation of the definition of limiting similarity and a roughly correct invasion criterion, which, however, is invalid for many-species societies.

Plants, Plants (Organisms), Competition (Biology), Plant competition

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