Refugia
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In the most basic biological sense refugia (singular: refugium) refer to locations of isolated or relict populations of once widespread animal or plant species. This isolation (allopatry) can be the result of human activities - such as deforestation, over hunting, etc. - or climatic changes. Present examples of such refuge species may be the mountain gorilla, now isolated to specific mountains in central Africa, and the Australian Sea Lion, presently isolated to specific breeding beaches in south Australia due to over hunting. This isolation, in many cases, can be seen as only a temporary state; however, some refugia may be long-standing, thereby having many endemic species, not found elsewhere, which survive as relict populations.
More specifically, however, Jürgen Haffer first proposed the concept of refugia to help explain the biological diversity of bird populations in the Amazonian river basin. Haffer forwarded that climatic change in the late Pleistocene led to reduced reservoirs of habitable forests in which populations become allopatric. Over time the various species in these refugia evolved differently from their counterpart species in different refugia. As the Pleistocene came to an end, the more arid conditions gave way to the present humid rainforest environment, reconnecting the refugia. However, the period of isolation was sufficient to cause speciation events, turning these once unified species into parapatric sister species.
This mode of speciation has since been expanded, being used to explain population patterns in other areas of the world, such as Africa and North America. Theoretically, current biogeographical patterns can be used to infer past refugia: where several unrelated species follow concurrent range patterns, it may be the case that that area was once a refugium. Speciation by this model is still highly controversial, however.
[edit] See also
[edit] References
- Coyne, Jerry A. & Orr, H. Allen. 2004. Speciation. Sunderland: Sinauer Associates, Inc. ISBN 0-87893-091-4
- Haffer, Jurgen. 1969. Speciation in Amazonian Forest Birds. Science. Vol. 165:131-137.
