Keanekaragaman hayati: Perbedaan antara revisi
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[[Berkas:River gambia Niokolokoba National Park.gif|jmpl|Hutan hujan adalah contoh keanekaragaman hayati di planet ini, dan biasanya memiliki /banyak keanekaragaman spesies. Ini adalah Sungai Gambia di Taman Nasional Niokolokoba, Senegal.]]
'''Keanekaragaman hayati''' atau '''biodiversitas''' adalah variasi dan [[Variabilitas genetik|variabilitas]] [[Kehidupan|kehidupan di Bumi]]. Keanekaragaman hayati biasanya merupakan ukuran variasi pada tingkat [[Genetika|genetik]], [[spesies]], dan [[ekosistem]].<ref name="UN">{{cite web |url=http://www.unesco.pl/fileadmin/user_upload/pdf/BIODIVERSITY_FACTSHEET.pdf |title=What is biodiversity? |publisher=[[United Nations Environment Programme]], World Conservation Monitoring Centre}}</ref> Biodiversitas terestrial biasanya lebih besar di sekitar khatulistiwa,<ref>{{cite journal |last=Gaston |first=Kevin J. |title=Global patterns in biodiversity|journal=Nature|date=11 May 2000 |volume=405 |issue=6783 |pages=220–227 |doi=10.1038/35012228 |pmid=10821282}}</ref> akibat [[iklim]] yang hangat dan [[Produksi primer|produktivitas primer]] ([[aliran energi]]) yang tinggi.<ref>{{cite journal | last=Field | first=Richard | author2=Hawkins, Bradford A. |author3=Cornell, Howard V. |author4=Currie, David J. |author5=Diniz-Filho, J. |others=Alexandre F.; Guégan, Jean-François; Kaufman, Dawn M.; Kerr, Jeremy T.; Mittelbach, Gary G.; Oberdorff, Thierry; O’Brien, Eileen M.; Turner, John R. G.|title=Spatial species-richness gradients across scales: a meta-analysis|journal=Journal of Biogeography|date=1 January 2009|volume=36|issue=1|pages=132–147|doi=10.1111/j.1365-2699.2008.01963.x| url=https://semanticscholar.org/paper/fc7ef261a9e652f23b9638f14cc1ecbcb8cba086 }}</ref> Keanekaragaman hayati tidak terdistribusi secara merata di Bumi, dan paling bervariasi di daerah [[Tropika|tropis]].<ref>{{Cite book|last=Gaston|first=Kevin J.|url=https://books.google.ca/books?hl=en&lr=&id=0Bjp2o5CVnQC&oi=fnd&pg=PT6&dq=biodiversity&ots=Y02cZSibGx&sig=05jb5PGTllW1YN721tNuh9lYuN4#v=onepage&q=biodiversity&f=false|title=Biodiversity: An Introduction|last2=Spicer|first2=John I.|date=2013-04-22|publisher=John Wiley & Sons|isbn=978-1-118-68491-7|language=en}}</ref> Meskipun ekosistem hutan tropis hanya mencakup 10 persen dari permukaan Bumi, tapi memiliki sekitar 90 persen spesies yang ada di dunia.<ref>Young, Anthony. "Global Environmental Outlook 3 (GEO-3): Past, Present and Future Perspectives." ''The Geographical Journal'', vol. 169, 2003, p. 120.</ref> [[Biologi kelautan|Keanekaragaman hayati laut]] biasanya tertinggi di sepanjang pantai di [[Samudra Pasifik|Pasifik]] Barat, tempat [[suhu permukaan laut]] paling tinggi, dan di pita pertengahan-lintang di semua lautan. Ada gradien
Perubahan lingkungan yang cepat biasanya menyebabkan [[kepunahan massal]].<ref name="CockellKoeberl2006">{{cite book |title=Biological Processes Associated with Impact Events |author1=Charles Cockell |author2=Christian Koeberl |author3=Iain Gilmour |last-author-amp=yes |url={{google books |plainurl=y |id=lWUPfhXPm4MC}} |date=18 May 2006 |publisher=Springer Science & Business Media|isbn=978-3-540-25736-3|pages=197–219|edition=1|bibcode=2006bpai.book.....C }}</ref><ref>{{cite journal|last=Algeo|first=T. J.|author2=Scheckler, S. E.|title=Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events|journal=Philosophical Transactions of the Royal Society B: Biological Sciences|date=29 January 1998|volume=353|issue=1365|pages=113–130|doi=10.1098/rstb.1998.0195|pmc=1692181}}</ref><ref>{{cite journal|last=Bond|first=David P.G.|author2=Wignall, Paul B.|title=The role of sea-level change and marine anoxia in the Frasnian–Famennian (Late Devonian) mass extinction|journal=Palaeogeography, Palaeoclimatology, Palaeoecology|date=1 June 2008|volume=263|issue=3–4|pages=107–118|doi=10.1016/j.palaeo.2008.02.015|url=http://eprints.whiterose.ac.uk/3460/1/bondb2.pdf}}</ref> Lebih dari 99,9 persen dari semua spesies yang pernah hidup di Bumi, yang berjumlah lebih dari lima miliar spesies,<ref name="Book-Biology">{{cite book |editor1=Kunin, W.E. |editor2=Gaston, Kevin |title=The Biology of Rarity: Causes and consequences of rare—common differences|url={{google books |plainurl=y |id=4LHnCAAAQBAJ|page=110}}|date=31 December 1996 |isbn=978-0-412-63380-5 |accessdate=26 May 2015 }}</ref> diperkirakan telah [[Kepunahan|punah]].<ref name="StearnsStearns2000">{{cite book |last=Stearns |first=Beverly Peterson |last2=Stearns |first2=S. C. |last3=Stearns |first3=Stephen C. |title=Watching, from the Edge of Extinction |url=https://books.google.com/books?id=0BHeC-tXIB4C&q=99%20percent#v=onepage&q=99%20percent&f=false |year=2000 |publisher=[[Yale University Press]] |isbn=978-0-300-08469-6|page=preface x |accessdate=30 May 2017 }}</ref><ref name="NYT-20141108-MJN">{{cite news |last=Novacek |first=Michael J. |title=Prehistory's Brilliant Future |url=https://www.nytimes.com/2014/11/09/opinion/sunday/prehistorys-brilliant-future.html |date=8 November 2014 |work=[[The New York Times]] |accessdate=25 December 2014 }}</ref> Perkiraan jumlah spesies Bumi saat ini berkisar antara 10 juta hingga 14 juta;<ref name="MillerSpoolman2012">{{cite book|author1=G. Miller|author2=Scott Spoolman |title=Environmental Science – Biodiversity Is a Crucial Part of the Earth's Natural Capital |url={{google books |plainurl=y |id=NYEJAAAAQBAJ|page=62}} |date=2012 |publisher=[[Cengage Learning]] |isbn=978-1-133-70787-5 |page=62 |accessdate=27 December 2014 }}</ref> sekitar 1,2 juta spesies telah didokumentasikan, dan lebih dari 86 persen di antaranya belum dideskripsikan.<ref name="PLoS-20110823">{{cite journal |last1=Mora |first1=C. |last2=Tittensor |first2=D.P. |last3=Adl |first3=S. |last4=Simpson |first4=A.G. |last5=Worm |first5=B. |title=How many species are there on Earth and in the ocean? |date=23 August 2011 |journal=[[PLOS Biology]] |doi=10.1371/journal.pbio.1001127 |pmid=21886479 |pmc=3160336 |volume=9 |issue=8 |pages=e1001127}}</ref> Pada Mei 2016, para ilmuwan melaporkan bahwa diperkirakan ada 1 triliun spesies yang berada di Bumi saat ini, dan hanya seperseribu dari satu persen yang telah dideskripsikan.<ref name="NSF-2016002">{{cite news |author=Staff |title=Researchers find that Earth may be home to 1 trillion species |url=https://www.nsf.gov/news/news_summ.jsp?cntn_id=138446 |date=2 May 2016 |work=[[National Science Foundation]] |accessdate=6 May 2016 }}</ref> Jumlah total [[pasangan basa]] [[Asam deoksiribonukleat|DNA]] terkait di Bumi diperkirakan 5,0 x 10<sup>37</sup> dengan berat 50 miliar ton.<ref name="NYT-20150718-rn">{{cite news |last=Nuwer |first=Rachel |date=18 July 2015 |title=Counting All the DNA on Earth |url=https://www.nytimes.com/2015/07/21/science/counting-all-the-dna-on-earth.html |work=The New York Times |location=New York |publisher=The New York Times Company |issn=0362-4331 |accessdate=18 July 2015}}</ref> Sebagai perbandingan, total [[Biomassa (ekologi)|massa]] [[biosfer]] diperkirakan sebanyak 4 TtC (triliun ton [[karbon]]).<ref name="AGCI-2015">{{cite web |url=http://www.agci.org/classroom/biosphere/index.php |title=The Biosphere: Diversity of Life |author=<!--Staff writer(s); no by-line.--> |work=Aspen Global Change Institute |location=Basalt, CO |accessdate=19 July 2015}}</ref> Pada Juli 2016, para ilmuwan mengidentifikasi satu set yang terdiri atas 355 [[gen]] dari [[leluhur universal terakhir]] (LUCA) dari semua [[Makhluk hidup|organisme]] yang hidup di Bumi.<ref name="NYT-20160725">{{cite news |last=Wade |first=Nicholas |authorlink=Nicholas Wade |title=Meet Luca, the Ancestor of All Living Things |url=https://www.nytimes.com/2016/07/26/science/last-universal-ancestor.html |date=25 July 2016 |work=[[The New York Times]] |accessdate=25 July 2016 }}</ref>
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