Colonization in metapopulations: a review of theory and observations

In metapopulation dynamics turnover of populations in isolated patches may be frequent. Regional survival of aspecies in such a system with frequent extinctions hinges on its colonization ability. Colonization is more than justdispersal; when a propagule reaches a new patch it faces higher extinction probabilities than does an established population. Extinction models as well as empirical data suggest that a large propagule with a potential for rapid increase in a varyingenvironment, or with a low mortality rate in an environment perceived as constant, has a higherprobability of successful colonization. Large variation in population size when it is still small increases the risk offailure. Factors introducing such variation are demographic stochasticity and environmental variation. It is hard to singleout demographic traits that ensure good colonizing ability, since colonization can be achieved in many different ways, butgeneralists and species with self-fertilization seem to be superior.