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 continu ous character) averaged over all individuals belonging to the population. T he populations interact by exchanging genetic information (gene flow) and c ompeting in the natural selection. We show, via Monte Carlo simulations, th at the extinction rate of the populations depends crucially on two factors - interactions between the populations and the changes of the external cond itions. Apart from big cataclysms, increased rate of extinctions in the sys tem of interacting populations may be also provoked by small, but correlate d, 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. (C) 1999 Elsevier Science B.V. All righ ts reserved.