Endemism

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This article is about the ecological meaning of "endemic". For the epidemiological meaning, see Endemic (epidemiology).
The orange-breasted sunbird (Nectarinia violacea) is exclusively found in fynbos vegetation.

Endemism is the ecological state of a species being unique to a defined geographic location, such as an island, nation, country or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. The extreme opposite of endemism is cosmopolitan distribution. Another term for a species that is endemic is precinctive, which applies to species (and subspecific categories) that are restricted to a defined geographical area.

Etymology[edit]

The word endemic entered the English language in the 17th century. It comes from the New Latin word endēmicus, which is the latinisation of the Greek word endēmos, meaning "native." Endēmos is formed of the words en, "in," and dēmos, "the people."[1]

Overview[edit]

Physical, climatic, and biological factors can contribute to endemism. The orange-breasted sunbird is exclusively found in the fynbos vegetation zone of southwestern South Africa. The glacier bear is found only in limited places in Southeast Alaska. Political factors can play a part if a species is protected, or actively hunted, in one jurisdiction but not another.

There are two subcategories of endemism – paleoendemism and neoendemism. Paleoendemism refers to a species that was formerly widespread but is now restricted to a smaller area. Neoendemism refers to a species that has recently arisen such as a species that has diverged and become reproductively isolated, or one that has formed following hybridization and is now classified as a separate species. This is a common process in plants, especially those that exhibit polyploidy.

Endemic types or species are especially likely to develop on biologically isolated areas such as islands because of their geographical isolation. This includes remote island groups, such as Hawaii, the Galápagos Islands, and Socotra, biologically isolated but not island areas such as the highlands of Ethiopia, or large bodies of water like Lake Baikal.

Endemics can easily become endangered or extinct if their restricted habitat changes, particularly but not only due to human actions, including the introduction of new organisms. There were millions of both Bermuda petrels and "Bermuda cedars" (actually junipers) in Bermuda when it was settled at the start of the seventeenth century. By the end of the century, the petrels were thought extinct. Cedars, already ravaged by centuries of shipbuilding, were driven nearly to extinction in the twentieth century by the introduction of a parasite. Bermuda petrels and cedars, although not actually extinct, are very rare today, as are other species endemic to Bermuda.

Origin of the term precinctive[edit]

Precinctive seems to have been coined by eminent biogeographer and systematist David Sharp when he was discussing the Hawaiian fauna.[2] He stated: “I use the word precinctive in the sense of ‘confined to the area under discussion … precinctive forms’ means those forms that are confined to the area specified.” That definition excludes artificial confinement of examples by humans in far-off botanical gardens or zoological parks.

Sharp coined the word precinctive because he objected to use of the word ‘endemic’ for such use, writing that “I use the word precinctive in preference to endemic or peculiar – both of which are in common use – in the sense of confined to the area under discussion. The word endemic has been objected to on the grounds that its definition does not indicate geographical restriction and that it is actually used in medicine to signify constant, but not necessarily exclusive presence in a locality.”

Sharp’s criticism of use of the word ‘endemic’ in the biogeographic sense was valid. When the word endemic was first used in English (from French, and originally spelled ‘endemique’ and given as the antonym of ‘epidemique’[3]) it dealt with populations of human pathogens. Later the spelling was changed to ‘endemick’ but the subject still was epidemiology and the prevalence of pathogens, not geographic restriction.[4] Biogeography is a discipline distinct from ecology.[5] The ecological use of ‘endemic’ became expanded to plant pathogens and plants and animals, and is exemplified by Southwood and Comins: “The change from epidemic to endemic level may occur because…”[6] and by Price “When the effect of enemies is disrupted or environmental conditions become particularly favorable for reproduction, the population escapes the stabilizing influence of enemies … and increases to epidemic proportions … However, shortage of food and disease may lead to massive mortality and low natality causing the population to crash to … endemic levels.”[7] In ecology, endemic is the antonym of epidemic. It applies to populations of any kind of organism in which very high densities can alternate with very low ones.

Most biologists ignored Sharp’s coining of the word precinctive, and continued ‘thundering down the wrong track’ in using the late 19th century use of ‘endemic’ in a biogeographic sense instead of its original ecological sense. The result is that there are two major uses of the word ‘endemic’: (1) its original ecological sense (epidemiology and population dynamics, dating back to the early 17th century), and (2) its biogeographic sense dating back to the late 19th century. A third meaning arose when some 20th century writers began to confuse the term ‘indigenous’ with the biogeographic concept of ‘endemic’.

Some of the subsequent uses of the word precinctive can be found in Sharp, D. and Scott, H. 1908,[8] Cockerell, T.D.A. 1914,[9] MacCaughey, V. 1916,[10] Bequaert, J. 1921 [11] and 1940,[12] Gressitt, J.L. 1960,[13] Snelling, R.R. 1966,[14] Mackerras, I.M. 1970,[15] Liebherr, J.K. 1997,[16] Whitehead, D.R. and Ball, G.E. 1997,[17] McCoy, E.D. and Mushinsky, H.R. 1999,[18] Bossart, J.L. and Carlton, C.E. 2002,[19] Majka, C.G. and Sikes, D.S. 2009,[20] and Hughes, M.A., Shin, K., Eickwort, J. and Smith, J.A. 2012.[21]

Precinctivity vs. precinction[edit]

Precinctivity (a noun) is the condition of being restricted to a specified geographical area. Apparently first used by MacCaughey in 1917. It is the equivalent of the word ‘endemism’, which was based on the misappropriated word ‘endemic’ in its biogeographical sense.[22]

Precinction (a noun) is the condition of being restricted to a geographical area. Perhaps first used by Frank and McCoy (based on a word that had been used in English in 1730 meaning girdled about) who apparently failed to notice the earlier use of ‘precinctivity’ by MacCaughey 1917 in the botanical literature.[23][24]

Ecoregions with high endemism/precinctivity[edit]

According to the World Wildlife Fund, the following ecoregions have the highest percentage of endemic plants:

Threats to highly endemistic regions[edit]

Some of the principal causes of habitat degradation and loss in these ecosystems are:

  • Agriculture
  • Urban growth
  • Surface mining
  • Mining of oil, metals and minerals
  • Large scale logging operations[41][42]
  • Slash-and-burn techniques employed by some cultures.

See also[edit]

References[edit]

  1. ^ "Endemic". Reference.com. Retrieved 6 december 2014.
  2. ^ Sharp, D. 1900. Coleoptera. I. Coleoptera Phytophaga, p. 91-116 in D. Sharp [ed.]. Fauna Hawaiiensis, Being the Land-Fauna of the Hawaiian Islands. Cambridge Univ. Press; Cambridge, vol. 2 part 3 [see p. 91].
  3. ^ Lodge, T. 1603. A treatise of the plague: Containing the nature, signes, and accidents of the same, with the certaine and absolute cure of the fevers, botches and carbuncles that raigne in these times: And above all things most singular experiments and preservatives in the same, gathered by the observation of divers worthy travailers and selected out of the writings of the best learned phisitians in this age. Edward White and N.L., London [reprinted 1979, Theatrum Orbis Terrarum, Amsterdam].
  4. ^ Malthus, T.R. 1803. An essay on the principle of population; Or, a view of its past and present effects on human happiness; With an inquiry into our prospects respecting the future removal or mitigation of the evils which it occasions. J. Johnson, London, xi+610 pp.
  5. ^ Krebs, C.J. 1972. Ecology. Harper and Row, New York.
  6. ^ Southwood, T.R.E. and Comins, H.N. 1976. A synoptic population model. Journal of Animal Ecology 45: 949-965.
  7. ^ Price, P.W. 1984. Insect Ecology. John Wiley, New York.
  8. ^ Sharp, D. and Scott, H. 1908. Coleoptera Cleridae to Hydrophilidae, p. 367-578 in D. Sharp [ed.] Fauna Hawaiiensis, Being the Land-Fauna of the Hawaiian Islands. Cambridge Univ. Press; Cambridge, vol. 3 part 5. [see p. 435]
  9. ^ Cockerell, T.D.A. 1914. The endemic mammals of the British Islands. American Naturalist 48: 177-184 [see p. 177].
  10. ^ MacCaughey, V. 1916. Precinctive flora of the Waianae Mountains, Oahu: An annotated reference list of seventy species and varieties. Hawaiian Forester 13: 85-89.
  11. ^ Bequaert, J. 1921. On Eumenes alluaudi Perez, a precinctive wasp of the Seychelles (Hymenoptera). Psyche 28: 160-164 http://dx.doi.org/10.1155/1921/78616
  12. ^ Bequaert, J. 1940. The Tabanidae (Dipt.) of the Antilles. Revista de Entomologia, Rio de Janeiro 11: 253-369. [see p. 256]
  13. ^ Gressitt, J.L. 1960. Hispine beetles from New Caledonia (Chrysomelidae). Pacific Insects 2: 101-121 [see p. 101]
  14. ^ Snelling, R.R. 1966. Studies on North American bees of the genus Hylaeus 1. Distribution of the western species of the genus Prosopis with description of new forms (Hymenoptera: Colletidae). Contributions in Science, Los Angeles County Museum 98: 1-18.
  15. ^ Mackerras, I.M. 1970. Composition and distribution of the fauna p. 187-203 in The Insects of Australia. Melbourne Univ. Press, Carlton, Victoria [see p. 192].
  16. ^ Liebherr, J.K. 1997. Review of Antillean Glyptolenus Bates (Coleoptera: Carabidae), with description of a new species precinctive to St. Vincent. Studies on Neotropical Fauna and Environment 32: 89-99. http://dx.doi.org/10.1080/01650521.1997.9709610
  17. ^ Whitehead, D.R. and Ball, G.E. 1997. The Middle American genus Onypterygia Dejean (Insecta: Coleoptera: Carabidae: Platynini): A taxonomic revision of the species, with notes about their way of life and geographical distribution. Annals of Carnegie Museum 66: 289-409. [also uses word precinction]. http://www.ots.ac.cr/bnbt/15276.html
  18. ^ McCoy, E.D. and Mushinsky, H.R. 1999. Habitat fragmentation and the abundances of vertebrates in the Florida scrub. Ecology 80: 2526-2538 [see p. 2530].
  19. ^ Bossart, J.L. and Carlton, C.E. 2002. Insect conservation in America: Status and perspectives. American Entomologist 48: 82-92. [see p. 88] http://www.entsoc.org/PDF/Pubs/Periodicals/AE/AE-2002/summer/Feature-Bossart.pdf
  20. ^ Majka, C.G. and Sikes, D.S. 2009. Thomas L. Casey and Rhode Island’s precinctive beetles Taxonomic lessons and the utility of distributional lists. ZooKeys 22: 267-283. http://www.pensoft.net/J_FILES/1/articles/93/93-G-1-layout.pdf
  21. ^ Hughes, M.A., Shin, K., Eickwort, J. and Smith, J.A. 2012. First report of laurel wilt disease caused by Raffaelea lauricola on silk bay in Florida. Plant Disease 96: 910-911. http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-02-12-0149-PDN
  22. ^ MacCaughey, V. 1917. A survey of the Hawaiian land flora. Botanical Gazette 64: 89-114 [see p. 92]. http://www.jstor.org/stable/2469367
  23. ^ Frank, J.H. and McCoy, E.D. 1990. Endemics and epidemics of shibboleths and other things causing chaos. Florida Entomologist 73: 1-9. http://journals.fcla.edu/flaent/article/view/58577/56256
  24. ^ Frank, J.H. and McCoy, E.D. 1995. Precinctive insect species in Florida. Florida Entomologist 78: 21-35. [also uses word precinction]. http://journals.fcla.edu/flaent/article/view/74657/72315
  25. ^ "Lowland fynbos and renosterveld". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  26. ^ "Hawaii tropical dry forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  27. ^ "Hawaii tropical moist forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  28. ^ "Swan Coastal Plain Scrub and Woodlands". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  29. ^ "Madagascar dry deciduous forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  30. ^ "Madagascar lowland forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  31. ^ "New Caledonia dry forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  32. ^ "New Caledonia rain forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  33. ^ "Sierra Madre de Oaxaca pine-oak forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  34. ^ "Sierra Madre del Sur pine-oak forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  35. ^ "Luzon montane rain forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  36. ^ "Luzon rain forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  37. ^ "Luzon tropical pine forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  38. ^ "Mindanao montane rain forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  39. ^ "Mindanao-Eastern Visayas rain forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  40. ^ "Palawan rain forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 26 January 2010. 
  41. ^ Fred Smiet (1982). Threats to the Spice Islands. Oryx, 16 , pp 323-328 doi:10.1017/S0030605300017774
  42. ^ Frontiers in Ecology and the Environment 5: 25–32.

Further reading[edit]

  • CDL Orme, RG Davies, M Burgess, F Eigenbrod, et al. (18 August 2005). "Global hotspots of species richness are not congruent with endemism or threat". Nature 436 (7053): 1016–9. doi:10.1038/nature03850. PMID 16107848.