Evolution of populations in a changing environment

A model of a system of populations (metapopulation) is presented in which a population is characterized by a mean phenotype (or equivalently a continuous character) averaged over all individuals belonging to the population. The populations interact by exchanging genetic information (gene flow) and competing in the natural selection. We show, via Monte Carlo simulations, that the extinction rate of the populations depends crucially on two factors – interactions between the populations and the changes of the external conditions. Apart from big cataclysms, increased rate of extinctions in the system of interacting populations may be also provoked by small, but correlated, changes in the environment. As in the case of a constant habitat, which leads to a steady extinction rate, there are only three possible scenarios for the fate of the metapopulation.