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Extinction

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Bufo periglenes, the Gowden Taid, wis last recordit on 15 Mey 1989
Extinct
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In biology an ecology, extinction is the end o an organism or o a group o organisms (taxon), normally a speshies. The moment o extinction is generally conseedert tae be the daith o the last individual o the species, awtho the capacity tae breed an rekiver mey hae been lost afore this pynt. Acause a species' potential range mey be verra lairge, determinin this moment is difficult, an is uisually duin retrospectively. This difficulty leads tae phenomena sic as Lazarus taxa, whaur a speshies presumed extinct abruptly "reappears" (teepically in the fossil record) efter a period o apparent absence.

Mair nor 99 percent o aw speshies, amoontin tae ower five billion speshies,[1] that iver leeved on Yird are estimatit tae hae dee'd oot.[2][3][4] Estimates on the nummer o Yird's current species range frae 10 million tae 14 million,[5] o that aboot 1.2 million hae been documentit an ower 86 percent hae nae yet been descrived.[6] In 2016, scientists reportit that 1 trillion speshies are estimatit tae be on Yird the noo wi anerly ane thoosandt o ane percent descrived.[7]

Throu evolution, speshies arise throu the process o speciation—whaur new varieties o organisms arise an thrive whan thay are able tae find an exploit an ecological niche—an speshies become extinct whan thay are nae langer able tae survive in chyngin condeetions or agin superior competeetion. The relationship atween ainimals an thair ecological niches haes been firmly established.[8] A teepical speshies becomes extinct within 10 million years o its first appearance,[4] awtho some speshies, cried leevin fossils, survive wi little tae nae morphological chynge for hunners o millions o years.

Mass extinctions are relatively rare events; houiver, isolatit extinctions are quite common. Anerly recentlik hae extinctions been recordit an scientists hae become alairmed at the current heich rate o extinctions.[9][10][11][12] Maist speshies that become extinct are niver scienteefically documentit. Some scientists estimate that up tae hauf o presently existin plant an ainimal speshies mey become extinct bi 2100.[13] A 2018 report indicatit that the phylogenetic diversity o 300 mammalian speshies erased in the human era syne the Late Pleistocene wad require 5 tae 7 million years tae rekiver.[14]

Accordin tae the 2019 Global Assessment Report on Biodiversity an Ecoseestem Services bi IPBES, the biomass o wild mammals haes fawen bi 82%, naitural ecoseestems hae lost aboot hauf thair area an a million speshies are at risk o extinction—aw lairgely as a result o human actions. Twinty-five percent o plant an ainimal species are threitent wi extinction.[15][16][17]

In Juin 2019, ane million speshies o plants an ainimals war at risk o extinction. At least 571 speshies are lost syne 1750 but likely mony mair. The main cause o the extinctions is the destruction o naitural habitats bi human acteevities, sic as cuttin doun forests an convertin laund intae fields for fermin.[18]

A dagger seembol (†) placed next tae the name o a speshies or ither taxon normally indicates its status as extinct.

References

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  1. ↑ Kunin, W.E.; Gaston, Kevin, eds. (1996). The Biology of Rarity: Causes and consequences of rare–common differences. ISBN 978-0412633805. Retrieved 26 Mey 2015.
  2. ↑ Stearns, Beverly Peterson; Stearns, S.C.; Stearns, Stephen C. (2000). Watching, from the Edge of Extinction. Yale University Press. p. preface x. ISBN 978-0-300-08469-6. Retrieved 30 Mey 2017.
  3. ↑ Novacek, Michael J. (8 November 2014). "Prehistory's Brilliant Future". The New York Times. Retrieved 25 December 2014.
  4. ↑ a b Newman, Mark (1997). "A model of mass extinction". Journal of Theoretical Biology. 189 (3): 235–252. arXiv:adap-org/9702003. doi:10.1006/jtbi.1997.0508. PMID 9441817.
  5. ↑ G. Miller; Scott Spoolman (2012). Environmental Science – Biodiversity Is a Crucial Part of the Earth's Natural Capital. Cengage Learning. p. 62. ISBN 978-1-133-70787-5. Retrieved 27 December 2014.
  6. ↑ Mora, C.; Tittensor, D.P.; Adl, S.; Simpson, A.G.; Worm, B. (23 August 2011). "How many species are there on Earth and in the ocean?". PLOS Biology. 9 (8): e1001127. doi:10.1371/journal.pbio.1001127. PMC 3160336. PMID 21886479.
  7. ↑ Staff (2 Mey 2016). "Researchers find that Earth may be home to 1 trillion species". National Science Foundation. Retrieved 6 Mey 2016.
  8. ↑ Sahney, S.; Benton, M.J.; Ferry, P.A. (2010). "Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land". Biology Letters. 6 (4): 544–547. doi:10.1098/rsbl.2009.1024. PMC 2936204. PMID 20106856.
  9. ↑ Species disappearing at an alarming rate, report says. NBC News. Retrieved July 26, 2006.
  10. ↑ The Sixth Extinction on YouTube (PBS Digital Studios, November 17, 2014)
  11. ↑ Ceballos, Gerardo; Ehrlich, Paul R.; Barnosky, Anthony D.; García, Andrés; Pringle, Robert M.; Palmer, Todd M. (2015). "Accelerated modern human–induced species losses: Entering the sixth mass extinction". Science Advances. 1 (5): e1400253. Bibcode:2015SciA....1E0253C. doi:10.1126/sciadv.1400253. PMC 4640606. PMID 26601195.
  12. ↑ Ripple WJ, Wolf C, Newsome TM, Galetti M, Alamgir M, Crist E, Mahmoud MI, Laurance WF (13 November 2017). "World Scientists' Warning to Humanity: A Second Notice". BioScience. 67 (12): 1026–1028. doi:10.1093/biosci/bix125. Moreover, we have unleashed a mass extinction event, the sixth in roughly 540 million years, wherein many current life forms could be annihilated or at least committed to extinction by the end of this century.
  13. ↑ Wilson, E.O., The Future of Life (2002) (ISBN 0-679-76811-4). See also: Leakey, Richard, The Sixth Extinction : Patterns of Life and the Future of Humankind, ISBN 0-385-46809-1
  14. ↑ Davis M, Faurby S, Svenning JC (2018). "Mammal diversity will take millions of years to recover from the current biodiversity crisis". Proc Natl Acad Sci U S A. 115 (44): 11262–11267. doi:10.1073/pnas.1804906115. PMC 6217385. PMID 30322924.
  15. ↑ Watts, Jonathan (6 Mey 2019). "Human society under urgent threat from loss of Earth's natural life". The Guardian. Retrieved 6 Mey 2019.
  16. ↑ Plumer, Brad (6 Mey 2019). "Humans Are Speeding Extinction and Altering the Natural World at an 'Unprecedented' Pace". The New York Times. Retrieved 6 Mey 2019.
  17. ↑ Staff (6 Mey 2019). "Media Release: Nature's Dangerous Decline 'Unprecedented'; Species Extinction Rates 'Accelerating'". Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Retrieved 6 Mey 2019.
  18. ↑ "'Frightening' number of plant extinctions found in global survey". The Guardian. 10 Juin 2019.
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