Local extinction in a metapopulation context: an empirical evaluation



Metapopulations are classically viewed as sets of populations persisting in a balance between local extinction and colonization. When this is true, regional persistence depends critically upon parameters influencing extinction and colonization rates, e.g. the number of habitat patches and populations, the rates and patterns of interpatch migration, and propagule establishment probabilities. A review of relevant empirical literature identifies few metapopulations which fit this description well. Instead, three qualitatively different situations are found to be more common: (1) mainland-island and source-sink metapopulations, in which persistence depends on the existence of one or more extinction-resistant populations; (2) patchy populations, in which dispersal between patches or sub-populations is so high that the system is effectively a single extinction-resistant population; (3) non-equilibrium metapopulations, in which local extinction occurs in the course of a species' overall regional decline. This suggests a modified view of metapopulation dynamics in which local extinction is more an incidental than a central feature.