ABSTRACT
Simulation results obtained with an individual-based model describing spatial movement and interactions of predators and prey within a closed rectangular habitat are represented. Movement of each individual animal is determined by local conditions only, thus any collective behaviour emerges due to self-organization. It is shown that the pursuit of the prey by predators leads to the emergence of predator interference manifesting itself at the population level as the dependence of the trophic function on predator abundance (predator-dependence). The stabilizing effect of predator dependence on the dynamics of a predator-prey system has been discussed. The inclusion of prey evasion induces predators' cooperation that further distorts the functional response (the trophic function), leading to a strong Allee effect, i.e. extinction of predator population dropping below a critical threShold. Thus, we propose a simple mechanistic explanation of important but still poorly understood behavioural phenomena that underlie functioning of natural trophic systems.
Subject(s)
Food Chain , Models, Theoretical , Predatory Behavior , Animals , Ecosystem , Population DynamicsABSTRACT
Three predator-dependent trophic functions have been fitted to experimental data on individual ration of two phytophagous rotifers (Brachionus calyciflorus and Philodina acuticornis) in laboratory monocultures of microalgae (Chlorella vulgaris Beyer, Scenedesmus quadricauda Brev. and Synechocistis sp.). The best fit was obtained with theoretical dependence proposed in that generalises the Arditi-Ginzburg ratio-dependent trophic function, approaching the Holling type II expression when either predator or prey density becomes low. At the same time the obtained results suggest that the original ratio-dependent function of Arditi-Ginzburg can be effectively used for modelling trophic interactions in the considered systems, because individual ration of rotifers is determined by the ratio of microalgae to consumer abundances.
