Evolution and dispersal under climatic instability: a simple evolutionary algorithm

Abstract

It has long been known that temporally unstable environments are likely to promote the evolution of plastic adaptations, whilst it is equally clear that such adaptations are precisely those that characterize successful colonizers. These two established findings, however, are rarely related within a single framework. This article bridges this gap via the development of a very simple evolutionary algorithm that tracks both directional selection and the evolution of plasticity under various synthetic climatic regimes. The output of the model allows for the construction of a dispersal index that provides a measure of population-level dispersal potential under each particular climatic regime. The output thus establishes both the timing and extent of selection for plasticity and the consequences of that plasticity for the timing of probable dispersal events in the context of climatic instability. Results suggest that periods of low climatic instability abruptly following extended periods of higher climatic instability are particularly conducive to dispersal, leading to the formulation of the Accumulated Plasticity Hypothesis. These results, and the hypothesis they support, are discussed in relation to the varied manifestations of plasticity in biological systems and their relevance to human evolution.