Fragments, extinction, and recolonization: The genetics of metapopulations

Abstract

The idea of a metapopulation - a group of local populations in a patchy habitat - recurs in both ecology and evolutionary biology. Although the metapopulation concept is at least 50-75 years old, it has recently resurged, as natural habitats become fragmented and are lost because of humans' use of resources. However, fragmentation is not the same as habitat loss per se, and patchy habitats do not necessarily make metapopulations. Some populations may behave naturally as metapopulations and are characterized by extinction of some local populations and recolonization of empty patches from the occupied patches. Alternatively, other populations may be forced into a metapopulation dynamic by human-caused habitat fragmentation or other introduced disturbances. The genetic effects of habitat fragmentation or introduced disturbance are subtle and depend on frequency of migration between patches, rates of recolonization of empty patches, and levels of genetic variation before fragmentation began. Other than generally reducing population sizes, the effects of metapopulations on breeding practices or adaptive evolution depend on the amount of genetic variation remaining within local populations, how genetically differentiated from each other local populations become as a result of local extinctions and recolonization, the strength of natural or artificial selection, and whether selection is locally strong enough to result in adaptation to local conditions. We offer limber pine (Pinus flexilis James) as an example of a forest tree species that experiences metapopulation dynamics.

Citation

Antolin, Michael F.; Schoettle, Anna W. 2001. Fragments, extinction, and recolonization: The genetics of metapopulations. In: Joyce, D.; Simpson, J. D., eds. Proceedings of the Twenty-Seventh Meeting of the Canadian Tree Improvement Association: Genetic resource management : Building strategies for the new millennium; Sault Ste. Marie, Ontario; August 15-17, 2000. Natural Resources Canada, Canadian Forest Service. p. 37-46.