An Ecosystem Model with Evolutionary Adaptive Trophic Structure

Philip J. Underwood
Doctorate of Philosophy
The School of Environmental Sciences
University of East Anglia
September 2013

We live in an era of rapid change in ecosystems and their environments, that all scales up to the global. The contemporary view is that the interactions between life and the environment are bidirectional: the environment creates life and life creates the environment. However, most ecosystem models have an inbuilt rigidity such that the degrees to which they can mimic structural change in response to environmental cues is very limited. In an effort to capture the plasticity of life we present a new theoretical individual-based ecosystem model in the context of previous classical and experimental modelling approaches. The aim is to develop a deeper understanding of the factors determining trophic structure. The individual-based approach permits the inclusion of traits to model heritable attributes. Population-level models implement a mean-field approximation that led to the competitive exclustion principle. The addition of a trait to dene specic feeding strategy permits the model exploration of this problem. Life history theory predicts that reduced juvenile mortality selects for delayed maturity and decreased reproductive effort, and reduced adult mortality will select for the opposite. Through the inclusion of a different trait to represent relative parental investment in offspring, we explore the predictions of life history theory and hypotheses for clutch size.