Megafauna

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The mammoths constitute an extinct genus of megafauna.
The mammoths constitute an extinct genus of megafauna.

Megafauna are species of large animals (Greek μεγας, large, + modern Latin fauna, animal).

Definitions of what constitutes 'large' vary, with some authors using a 40 kg minimum,[1] others 44 kg,[2][3] 45 kg,[4] 100 kg,[5] or 250 kg.[6] In the last case, they may be further subdivided into small (250–500 kg), medium (500–1,000 kg) and large (over 1,000 kg) megafauna.[6] Others say that any particular limit is arbitrary, and do not favour a single minimum weight.[7]

The term is also used to refer to particular groups of large animals, both to extant species and, more often, those that have become extinct in the geologically recent Quaternary period.

Megafauna animals are generally K-strategists, with great longevity, slow population growth rates, low death rates, and few or no natural predators capable of killing adults. These characteristics make megafauna highly vulnerable to human exploitation. Some authors have argued that this reproductive capacity and ecological behaviour are more important than size alone, with some much smaller animals with very low reproductive rates showing 'megafauna' characteristics, such as all Tachyglossidae (echidnas) and Megatherioidea (two-toed sloths) above 7 kg and 6 kg respectively, having become extinct in late Quaternary megafaunal extinctions.[8]

Contents

[edit] Recent extinctions

Main article: Pleistocene megafauna

Many species of megafauna have become extinct within the last million years, and, although some biologists dispute it, human hunting is often cited as the cause.[9] Other theories for the cause of the extinctions are climatic change associated with glaciation and the questionable hyperdisease hypothesis.[10]

[edit] Examples of megafauna

[edit] Domestic megafauna

[edit] Freshwater megafauna

[edit] Oceanian megafauna

[edit] See also

[edit] References

  1. ^ Defense of the Earth. Past consequences of climate change: Evolutionary history of the mammals.
  2. ^ Stuart, A. J. (1991). Mammalian extinctions in the Late Pleistocene of northern Eurasia and North America. Biol. Rev. 66: 453–562.
  3. ^ Anon. Quaternary Paleobiology Update. The Quaternary Times 29 (1): (1999).
  4. ^ Corlett, R. T. (2006). Megafaunal extinctions in tropical Asia. Tropinet 17 (3): 1–3.
  5. ^ Martin, P. S. & Steadman, D. W. (1999). Prehistoric extinctions on islands and continents. In: Extinctions in near time: causes, contexts and consequences (MacPhee, R. D. E., ed.), pp. 17–56. New York: Kluwer/Plenum.
  6. ^ a b Choquenot, D., & Bowman, D. M. J. S. (1998). Marsupial Megafauna, Aborigines and the Overkill Hypothesis: Application of Predator-Prey Models to the Question of Pleistocene Extinction in Australia. Global Ecology and Biogeography Letters 7 (3): 167-180.
  7. ^ Wroe, S., Field, J., Fullagar, R., & Jermiin, L. S. (2004). Megafaunal extinction in the late Quaternary and the global overkill hypothesis. Alcheringa 28: 291-331.
  8. ^ Johnson, C. N. (2002). Determinants of loss of mammal species during the Late Quaternary 'megafauna' extinctions: life history and ecology, but not body size. Proc. Biol. Sci. 269 (1506): 2221–2227.
  9. ^ Diamond, J. (1997). Guns, Germs and Steel. Vintage ISBN 0-09-930278-0.
  10. ^ Grayson, D. K., & Meltzer, D. J. (2003). A requiem for North American overkill. Journal of Archaeological Science 30: 585–593.