Pedia View . com

Open Source Encyclopedia

Refugium (population biology)

European LGM refugia, 20 kya.

In biology, a refugium (plural: refugia), sometimes termed simply a refuge or a fuge, is a location of an isolated or relict population of a once more widespread species. This isolation (allopatry) can be due to climatic changes, geography, or human activities such as deforestation and over-hunting.

Present examples of refuge species are the mountain gorilla, isolated to specific mountains in central Africa, and the Australian Sea Lion, isolated to specific breeding beaches along the south-west coast of 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.

In anthropology, refugia often refers specifically to Last Glacial Maximum refugia, where some ancestral human populations may have been forced back to glacial refugia, similar small isolated pockets in the face of the continental ice sheets during the last ice age. Going from west to east, suggested examples include the Franco-Cantabrian region (in northern Iberia), the Italian, and Balkan peninsulas, Ukrainian LGM refuge, and the Bering land bridge.

Contents

Speciation

As an example of a locale refugia study, Jürgen Haffer first proposed the concept of refugia to explain the biological diversity of bird populations in the Amazonian river basin. Haffer suggested that climatic change in the late Pleistocene led to reduced reservoirs of habitable forests in which populations become allopatric. Over time, this led to speciation - populations of the same species which found themselves in different refugia evolved differently, creating parapatric sister-species. As the Pleistocene ended, the arid conditions gave way to the present humid rainforest environment, reconnecting the refugia.

Scholars have since expanded the idea of this mode of speciation and used it to explain population patterns in other areas of the world, such as Africa, Eurasia, and North America.However this model of speciation remains highly controversial. Theoretically, current biogeographical patterns can be used to infer past refugia: where several unrelated species follow concurrent range patterns, the area may have been a refugium. Moreover, current distribution of species with narrow ecological requirements tend to be associated with the spatial position of glacial refugia [1]

Simple environment examples of temperature

One can provide a simple explanation of refugia involving core temperatures and exposure to sunlight. In the northern hemisphere, north-facing sites on hills or mountains, and places at higher elevations count as cold sites. The reverse are sun- or heat-exposed, lower-elevation, south-facing sites: hot sites. (The opposite directions apply in the southern hemisphere.) Each site becomes a refugium, one as a "cold-surviving refugium", and the other as a "hot-surviving refugium". Canyons with deep hidden areas - the opposite of hillsides, mountains, mesas, etc., or other exposed areas - lead to these separate types of refugia.

A concept not often referenced is that of "sweepstakes colonization":[2] when a dramatic ecological event occurs, for example a bolide strike, and global, multiyear effects occur, the sweepstake-winning species happens to already be living in a fortunate site, and their environment is rendered even more advantageous, as opposed to the "losing" species, which immediately fail to reproduce.[3]

See also

Notes

  1. ^ Tarkhnishvili D, Gavashelishvili A, Mumladze L. 2012. Palaeoclimatic models help to understand current distribution of Caucasian forest species. Biol. J. Linn. Soc. 105:231-248
  2. ^ Forests of the Past. ("sweepstake dispersal"); Gulf of Guinia Islands Biodiverstiy Project. ("sweepstakes colonization")
  3. ^ Forests of the Past. ("sweepstake dispersal"); Gulf of Guinia Islands Biodiverstiy Project. ("sweepstakes colonization")
  4. ^ "Unepscs.org". Refugia.unepscs.org. Retrieved 2012-03-12.

References

Source

Content is authored by an open community of volunteers and is not produced by or in any way affiliated with ore reviewed by PediaView.com. Licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License, using material from the Wikipedia article on "Refugium (population biology)", which is available in its original form here:

http://en.wikipedia.org/w/index.php?title=Refugium_(population_biology)