Genetik xilma-xillik sahifasining manbasini koʻrish

[[Fayl:Human_karyotype.svg|thumb|Tipik inson [[Kariotip|kariotipining]] grafik tasviri.]]
'''Genetik xilma-xillik''' ({{lang-en|Genetic diversity}}) — turning genetik tuzilishidagi [[Genetika|genetik]] xususiyatlarning umumiy soni. U turlarning sonidan tortib [[Tur|turlar]] ichidagi farqlargacha keng ko'lamda o'zgarib turadi va turning yashab qolish davomiyligi bilan bog'liq bo'lishi mumkin.<ref>{{Cite web |last=biological online dictionary |first=genetic diversity |title=genetic diversity definition and examples |date=7 October 2019 |url=https://www.biologyonline.com/dictionary/genetic-diversity}}</ref> U genetik xususiyatlarning o'zgaruvchanlik tendentsiyasini tavsiflovchi ''[[Genetik o‘zgaruvchanlik|genetik o'zgaruvchanlik]]''dan farq qiladi.

Genetik xilma-xillik populyatsiyalar uchun o'zgaruvchan muhitga moslashish vositasi bo'lib xizmat qiladi. Variatsiya qanchalik ko'p bo'lsa, populyatsiyadagi ba'zi individlarning muhitga mos keladigan [[Allel|allellar]] (alleles) variatsiyasiga ega bo'lish ehtimoli shunchalik yuqori bo'ladi. Ushbu individlarning yashab qolishi va o'sha allelni tashuvchi nasl qoldirish ehtimoli yuqoriroqdir. Ushbu individlarning muvaffaqiyati tufayli populyatsiya ko'proq avlodlar davomida saqlanib qoladi.<ref name="U.S. Geological Survey">{{cite web |title=National Biological Information Infrastructure |work=Introduction to Genetic Diversity |publisher=U.S. Geological Survey |url=http://www.nbii.gov/portal/server.pt?open=512&objID=405&PageID=0&cached=true&mode=2&userID=2 |access-date=March 1, 2011 |archive-url=https://web.archive.org/web/20110225072641/http://www.nbii.gov/portal/server.pt?open=512&objID=405&PageID=0&cached=true&mode=2&userID=2 |archive-date=February 25, 2011}}</ref>
{{Evolutsion biologiya}}
[[Populyatsiya genetikasi]] (population genetics) akademik sohasi genetik xilma-xillikka oid bir qancha gipoteza va nazariyalarni o'z ichiga oladi. [[Evolyutsiyaning neytral nazariyasi]] (neutral theory of evolution) xilma-xillik neytral almashinishlarning to'planishi natijasi ekanligini ilgari suradi. [[Dizruptiv tanlanish|Dizruptiv (xilma-xillashtiruvchi) tanlanish]] — bu turning ikkita subpopulyatsiyasi muayyan lokusda turli xil allellarni tanlab oladigan turli muhitlarda yashashini nazarda tutuvchi gipotezadir. Bu holat, masalan, tur individlarning harakatchanligiga nisbatan keng tarqalish arealiga ega bo'lganda yuz berishi mumkin. [[Chastotaga bog'liq tanlanish]] — allellar qanchalik keng tarqalgan bo'lsa, ular shunchalik zaif bo'lib qolishini ifodalovchi gipotezadir. Bu [[Xo'jayin va patogen o'zaro ta'siri|xo'jayin va patogen o'zaro ta'sirida]] kuzatiladi, bunda [[Xo'jayin (biologiya)|xo'jayin]] organizmida himoya allelining yuqori chastotada uchrashi, agar [[patogen]] ushbu [[Allel|allelni]] yenga olsa, uning tarqalish ehtimoli yuqori bo'lishini anglatadi. 

== Tur ichidagi xilma-xillik ==
[[Fayl:Maize_diversity_in_Vavilovs_office_(3421259242).jpg|thumb|Rus o'simlikshunos genetigi [[Nikolay Vavilov]] ofisidagi [[makkajo'xori]] navlari]]
2007-yilda [[Milliy fan fondi]] (National Science Foundation) tomonidan o'tkazilgan tadqiqot shuni ko'rsatdiki, genetik xilma-xillik (tur ichidagi xilma-xillik) va [[biologik xilma-xillik]] (biodiversity) bir-biriga bog'liqdir — ya'ni, turlar orasidagi xilma-xillikni saqlash uchun tur ichidagi xilma-xillik zarur va aksincha. Tadqiqotning yetakchi olimi Doktor Richard Lankau ta'kidlashicha: «Agar tizimdan biror tur olib tashlansa, tsikl buzilishi va hamjamiyatda yagona tur hukmronlik qilishi mumkin».<ref name="enn">{{cite web |url=http://www.enn.com/animals/article/23391 |title=Study: Loss Of Genetic Diversity Threatens Species Diversity |access-date=8 May 2018}}</ref> [[Genotip|Genotipik]] va [[Fenotip|fenotipik]] xilma-xillik barcha turlarda [[oqsil]], [[DNK]] va [[organizm]] darajasida aniqlangan; tabiatda bu xilma-xillik tasodifiy emas, balki kuchli tuzilishga ega hamda atrof-muhit o'zgarishlari va [[Stress (biologiya)|stress]] bilan o'zaro bog'liqdir.<ref>{{cite journal|last=Nevo|first=Eviatar|title=Evolution of Genome-Phenome Diversity under Environmental Stress|journal=Proceedings of the National Academy of Sciences of the United States of America|date=May 2001|volume=98|issue=11|pages=6233–6240|jstor=3055788|doi=10.1073/pnas.101109298|pmid=11371642|pmc=33451|doi-access=free}}</ref>

Genetik va turlar xilma-xilligi o'rtasidagi o'zaro bog'liqlik juda nozikdir. Turlar xilma-xilligidagi o'zgarishlar atrof-muhitdagi o'zgarishlarga olib keladi va bu qolgan turlarning [[Moslashuv|moslashishiga]] (adaptation) sabab bo'ladi. Genetik xilma-xillikdagi o'zgarishlar, masalan, turlarning yo'qolishi, [[Biologik xilma-xillik|biologik xilma-xillikning]] qisqarishiga olib keladi.<ref name="U.S. Geological Survey" /> Uy hayvonlari populyatsiyalarida genetik xilma-xillikning yo'qolishi ham o'rganilgan bo'lib, bu bozorlarning kengayishi va [[iqtisodiy globallashuv]] (economic globalization) bilan bog'lanadi.<ref>{{cite book |year=2006 |title=Principles of Conservation Biology |url=https://archive.org/details/principlesofcons0000groo_a7l5 |edition=3rd |publisher=Sinauer Associates |author1=Groom, M. J. |author2=Meffe, G. K. |author3=Carroll, C. R.}} Website with additional information: http://www.sinauer.com/groom/ {{Webarchive|url=https://web.archive.org/web/20061230194641/http://www.sinauer.com/groom/|date=2006-12-30}}</ref><ref>{{Cite journal|doi=10.1016/S0921-8009(03)00091-0|last1=Tisdell|first1=C.|author-link=Clem Tisdell|date=2003|title=Socioeconomic causes of loss of animal genetic diversity: analysis and assessment|journal=Ecological Economics|volume=45|issue=3|pages=365–376|bibcode=2003EcoEc..45..365T|citeseerx=10.1.1.571.7424}}</ref>

== Neytral va adaptiv genetik xilma-xillik ==
Neytral genetik xilma-xillik [[Yashovchanlik|yashovchanlikni]] (fitness) oshirmaydigan va moslashuvchanlik uchun javobgar bo'lmagan [[Gen|genlardan]] iborat.<ref name=":1">{{Cite journal|last1=Holderegger|first1=Rolf|last2=Kamm|first2=Urs|last3=Gugerli|first3=Felix|date=2006|title=Adaptive vs. neutral genetic diversity: implications for landscape genetics|url=http://link.springer.com/10.1007/s10980-005-5245-9|journal=Landscape Ecology|language=en|volume=21|issue=6|pages=797–807|doi=10.1007/s10980-005-5245-9|bibcode=2006LaEco..21..797H|issn=0921-2973|hdl=20.500.11850/36333|s2cid=2070504|hdl-access=free}}</ref> [[Tabiiy tanlanish]] ushbu neytral genlarga ta'sir ko'rsatmaydi.<ref name=":1" /> Adaptiv genetik xilma-xillik yashovchanlikni oshiradigan va atrof-muhitdagi o'zgarishlarga moslashish uchun javobgar bo'lgan genlardan tashkil topgan.<ref name=":1" /> Adaptiv genlar ekologik, morfologik va xulq-atvor belgilariga javob beradi.<ref name=":2">{{Cite journal|last1=McHugh|first1=Anne|last2=Bierzychudek|first2=Paulette|last3=Greever|first3=Christina|last4=Marzulla|first4=Tessa|last5=Van Buskirk|first5=Richard|last6=Binford|first6=Greta|date=2013|title=A molecular phylogenetic analysis of Speyeria and its implications for the management of the threatened Speyeria zerene hippolyta|url=http://link.springer.com/10.1007/s10841-013-9605-5|journal=Journal of Insect Conservation|language=en|volume=17|issue=6|pages=1237–1253|doi=10.1007/s10841-013-9605-5|bibcode=2013JICon..17.1237M|s2cid=254596041|issn=1366-638X|url-access=subscription}}</ref> Tabiiy tanlanish adaptiv genlarga ta'sir ko'rsatadi, bu esa organizmlarning evolyutsiyasiga imkon beradi.<ref name=":1" /> Tanlanish ta'siri tufayli adaptiv genlardagi [[evolyutsiya]] tezligi neytral genlarga qaraganda yuqoriroqdir.<ref name=":2" /> Biroq, adaptiv genlar uchun allellarni aniqlash qiyin bo'lib kelmoqda, shu sababli adaptiv genetik xilma-xillik ko'pincha bilvosita o'lchanadi.<ref name=":1" /> Masalan, [[irsiy o'tuvchanlik]] <math>h^2=V_A/V_P</math> sifatida yoki [[QST (genetika)|adaptiv populyatsiya differentsiatsiyasi]] <math>Q_{ST}=V_G/(V_G+2V_A)</math> sifatida o'lchanishi mumkin.<ref name=":1" /> Populyatsiya darajasidagi genom ma'lumotlarini tahlil qilish orqali [[Genom bo'ylab assotsiativ tadqiqot|genom bo'ylab assotsiativ tadqiqotlar]] yordamida adaptiv genlarni aniqlash imkoni bo'lishi mumkin.<ref name=":4">{{Cite journal|last1=Willi|first1=Yvonne|last2=Kristensen|first2=Torsten N.|last3=Sgrò|first3=Carla M.|last4=Weeks|first4=Andrew R.|last5=Ørsted|first5=Michael|last6=Hoffmann|first6=Ary A.|date=2022-01-05|title=Conservation genetics as a management tool: The five best-supported paradigms to assist the management of threatened species|journal=Proceedings of the National Academy of Sciences|language=en|volume=119|issue=1|article-number=e2105076119|doi=10.1073/pnas.2105076119|doi-access=free|issn=0027-8424|pmc=8740573|pmid=34930821|bibcode=2022PNAS..11905076W}}</ref>

Adaptiv genetik xilma-xillikni aniqlash [[Tabiatni muhofaza qilish biologiyasi|tabiatni muhofaza qilish]] uchun muhimdir. Chunki turning adaptiv salohiyati, ayniqsa [[iqlim o'zgarishi]] jarayonida, uning omon qolishi yoki [[Qirilib ketish|qirilib ketishini]] belgilab berishi mumkin.<ref name=":1" /><ref name=":3">{{Cite journal|last1=Teixeira|first1=João C.|last2=Huber|first2=Christian D.|date=2021-03-09|title=The inflated significance of neutral genetic diversity in conservation genetics|journal=Proceedings of the National Academy of Sciences|language=en|volume=118|issue=10|article-number=e2015096118|doi=10.1073/pnas.2015096118|issn=0027-8424|pmc=7958437|pmid=33608481|arxiv=2007.02569|bibcode=2021PNAS..11815096T|doi-access=free}}</ref> Bu holat past darajadagi neytral genetik xilma-xillikning yuqori [[genetik dreyf]] va yuqori [[mutatsion yuk]] bilan bog'liqligi to'g'risidagi tushunchaning yetishmasligi tufayli yanada kuchayadi.<ref name=":3" /> Mavjud tadqiqotlar tahlilida Teyşeyra va Xuber (2021) ba'zi turlar, masalan ''[[Arabidopsis]]'' turkumiga mansublar, jiddiy [[populyatsiya bo'g'zi]] (bottlenecks) tufayli umumiy genetik xilma-xillikning pastligiga qaramay, yuqori adaptiv salohiyatga ega ekanligini aniqladilar.<ref name=":3" /> Shu sababli, past neytral genetik xilma-xillikka ega turlar yuqori adaptiv genetik xilma-xillikka ega bo'lishi mumkin. Biroq, adaptiv genlarni aniqlash qiyin bo'lganligi bois, umumiy genetik xilma-xillikni o'lchash tabiatni muhofaza qilish choralarini rejalashtirishda muhim ahamiyatga ega va genetik xilma-xilligi keskin kamaygan turlar qirilib ketish xavfiga o'ta moyil bo'lishi mumkin.<ref name=":3" /><ref name=":4" />

== Genetik xilma-xillikning evolyutsion ahamiyati ==

=== Moslashuv ===
Populyatsiya genofondidagi o'zgaruvchanlik [[Tabiiy tanlanish|tabiiy tanlanishga]] populyatsiyaning o'zgaruvchan muhitga moslashishini ta'minlaydigan belgilar ustida ta'sir o'tkazish imkonini beradi. Belgini tanlash yoki inkor etish o'zgaruvchan muhitda sodir bo'lishi mumkin — bu genetik xilma-xillikning oshishiga (agar yangi [[mutatsiya]] tanlanib, saqlanib qolsa) yoki kamayishiga (agar zararli allel tanlanish natijasida chiqarib tashlansa) olib keladi.<ref name="Wright2005">{{Cite book |last=Wright |first=Alan F. |date=September 2005 |chapter=Genetic Variation: Polymorphisms and Mutations |title=Encyclopedia of Life Sciences |edition=1 |language=en |publisher=Wiley |doi=10.1038/npg.els.0005005 |isbn=978-0-470-01617-6 |s2cid=82415195}}</ref> Shu sababli, genetik xilma-xillik turning yashab qolishi va moslashuvchanligida muhim ahamiyatga ega.<ref>{{cite journal|last=Frankham|first=Richard|title=Genetics and Extinction|url=https://archive.org/details/sim_biological-conservation_2005-11_126_2/page/131|journal=Biological Conservation|date=November 2005|volume=126|issue=2|pages=131–140|quote=The rate of evolutionary change (R) is determined primarily by the quantitative genetic variation|doi=10.1016/j.biocon.2005.05.002|bibcode=2005BCons.126..131F}}</ref> Populyatsiyaning o'zgaruvchan muhitga moslashish qobiliyati zaruriy genetik xilma-xillikning mavjudligiga bog'liq bo'ladi.<ref>{{cite book |last=Pullin |first=Andrew S. |date=2002 |title=Conservation biology |url=https://archive.org/details/conservationbiol0000pull |edition=1st |publisher=Cambridge University Press |isbn=978-0-521-64482-2}}</ref><ref name="Villemereuil">{{cite journal|last1=de Villemereuil|first1=Pierre|title=Little Adaptive Potential in a Threatened Passerine Bird|journal=Current Biology|date=2019|volume=29|issue=5|pages=889–894.e3|doi=10.1016/j.cub.2019.01.072|pmid=30799244|ref=Villemereuil|doi-access=free|bibcode=2019CBio...29E.889D}}</ref> Populyatsiyada genetik xilma-xillik qanchalik yuqori bo'lsa, uning moslashish va yashab qolish ehtimoli shunchalik yuqori bo'ladi. Aksincha, genetik xilma-xillikning kamayishi bilan populyatsiyaning iqlim o'zgarishi yoki yangi [[Kasallik|kasalliklar]] kabi o'zgarishlarga nisbatan zaifligi ortadi.<ref>{{cite journal|last1=King|first1=K. C.|last2=Lively|first2=C. M.|date=June 2012|title=Does genetic diversity limit disease spread in natural host populations?|journal=Heredity|volume=109|issue=4|pages=199–203|doi=10.1038/hdy.2012.33|pmc=3464021|pmid=22713998|bibcode=2012Hered.109..199K}}</ref> Masalan, koalalarning [[Xlamidiya]] va [[Koala retrovirusi|koala retrovirusiga]] (KoRV) qarshi kurashish uchun moslasha olmasligi ulardagi past genetik xilma-xillik bilan bog'liq.<ref name=":0">{{Cite news |title=Hanging in there: Koalas have low genetic diversity |language=en |work=ScienceDaily |url=https://www.sciencedaily.com/releases/2012/10/121023204636.htm |access-date=2018-06-06}}</ref> Ushbu past darajadagi genetik xilma-xillik genetiklarda koalalarning kelajakda iqlim o'zgarishi va inson ta'sirida yuzaga keladigan atrof-muhit o'zgarishlariga moslashish qobiliyati yuzasidan xavotir uyg'otmoqda.<ref name=":0" />

=== Kichik populyatsiyalar ===
Katta populyatsiyalarda genetik materialni saqlab qolish ehtimoli yuqoriroq va shu sababli ular odatda yuqori genetik xilma-xillikka ega bo'ladi.<ref name="Wright2005" /> Kichik populyatsiyalarda vaqt o'tishi bilan tasodifiy omillar tufayli xilma-xillikning yo'qolish ehtimoli yuqori bo'lib, bu [[Genetik dreyf|genetik dreyfning]] bir misolidir. Agar [[allel]] (gen varianti) fiksatsiyaga (muqimlanishga) uchrasa, xuddi shu lokusdagi boshqa allel yo'qoladi, bu esa genetik xilma-xillikning pasayishiga olib keladi.<ref>{{cite book |year=2002 |title=Introduction to Conservation Genetics |url=https://archive.org/details/introductiontoco0000fran |publisher=Cambridge University Press |author1=Frankham, Richard |author2=Ballou, Jonathan D. |author3=Briscoe, David A.}}</ref> Kichik o'lchamli populyatsiyalarda [[inbriding]] yoki o'xshash genetik tuzilishga ega individlar o'rtasida [[chatishish]] sodir bo'lish ehtimoli yuqoriroqdir. Bu keng tarqalgan allellarning fiksatsiya darajasiga qadar saqlanib qolishiga va natijada genetik xilma-xillikning kamayishiga olib keladi.<ref>{{cite journal|last=Crow|first=James F.|date=March 2010|title=Wright and Fisher on Inbreeding and Random Drift|doi-access=free|journal=Genetics|volume=184|issue=3|pages=609–611|doi=10.1534/genetics.109.110023|pmc=2845331|pmid=20332416}}</ref> Shu sababli, genetik xilma-xillik bilan bog'liq xavotirlar, ayniqsa, yirik sutemizuvchilar uchun juda muhimdir, chunki ularning populyatsiya o'lchami kichik va inson omili ta'siri yuqoridir.<sup>[[Genetic diversity#cite note-16|[16]]]</sup>

[[Populyatsiya bo'g'zi|Genetik bo'g'iz]] populyatsiya individlari soni kam bo'lgan davrni boshdan kechirganda yuzaga kelishi mumkin, bu esa genetik xilma-xillikning tez pasayishiga olib keladi. Populyatsiya hajmi oshgan taqdirda ham, agar butun tur kichik populyatsiyadan boshlangan bo'lsa, genetik xilma-xillik pastligicha qoladi. Chunki foydali mutatsiyalar (quyiga qarang) kam uchraydi va genofond kichik boshlang'ich populyatsiya bilan cheklangan bo'ladi.<ref>{{Cite web |url=https://evolution.berkeley.edu/evolibrary/article/conservation_04 |title=Low genetic variation |publisher=Understanding Evolution |website=Relevance of evolution: conservation |url-status=live |archive-url=https://web.archive.org/web/20210724041813/https://evolution.berkeley.edu/evolibrary/article/conservation_04 |archive-date=Jul 24, 2021}}</ref> Bu genetik jihatdan sog'lom qutqarilgan populyatsiya yoki tur ustida ishlashda [[tabiatni muhofaza qilish genetikasi]] sohasidagi muhim omildir.

=== Mutatsiya ===
Tasodifiy [[Mutatsiya|mutatsiyalar]] doimiy ravishda [[Genetik o‘zgaruvchanlik|genetik o'zgaruvchanlikni]] hosil qiladi.<ref name="Wright2005" /> Mutatsiya qisqa muddatda genetik xilma-xillikni oshiradi, chunki genofondga yangi gen kiritiladi. Biroq, ushbu genning saqlanib qolishi dreyf va tanlanishga (yuqoriga qarang) bog'liq. Ko'pchilik yangi mutatsiyalar yashovchanlikka (fitness) nisbatan neytral yoki salbiy ta'sir ko'rsatadi, ba'zilari esa ijobiy ta'sirga ega.<ref name="Wright2005" /> Foydali mutatsiyaning saqlanib qolish ehtimoli yuqoriroq bo'lib, u genetik xilma-xillikka uzoq muddatli ijobiy ta'sir ko'rsatadi. Mutatsiya tezligi genom bo'ylab farq qiladi va katta populyatsiyalarda mutatsiya ko'rsatkichlari yuqoriroq bo'ladi.<ref name="Wright2005" /> Kichik populyatsiyalarda mutatsiyaning saqlanib qolish ehtimoli kamroq, chunki u dreyf tufayli yo'qolib ketish xavfiga moyil bo'ladi.<ref name="Wright2005" />

=== Genlar oqimi ===
Ko'pincha migratsiya orqali sodir bo'ladigan [[genlar oqimi]] genetik materialning harakatlanishidir (masalan, shamoldagi gul changi yoki qushlarning migratsiyasi orqali). Genlar oqimi populyatsiyaga yangi allellarni kiritishi mumkin. Ushbu allellar populyatsiyaga integratsiyalashib, genetik xilma-xillikni oshiradi.<ref>{{cite journal|last=Frankham|first=Richard|title=Genetics and Extinction|url=https://archive.org/details/sim_biological-conservation_2005-11_126_2/page/131|journal=Biological Conservation|date=November 2005|volume=126|issue=2|pages=131–140|quote=The rate of evolutionary change (R) is determined primarily by the quantitative genetic variation|doi=10.1016/j.biocon.2005.05.002|bibcode=2005BCons.126..131F}}</ref>

Masalan, Afrikaning ''[[Anopheles gambiae]]'' chivinlarida [[Insektitsid|insektitsidga]] chidamli mutatsiya paydo bo'ldi. Ba'zi ''A. gambiae'' chivinlarining ''[[Anopheles coluzziin]]'' chivinlari populyatsiyasiga migratsiyasi foydali chidamlilik genining bir turdan ikkinchisiga o'tishiga olib keldi. Genetik xilma-xillik ''A. gambiae''da mutatsiya orqali, ''A. coluzziin''da esa genlar oqimi orqali ortdi.<ref>{{cite book |last=Pullin |first=Andrew S. |date=2002 |title=Conservation biology |url=https://archive.org/details/conservationbiol0000pull |edition=1st |publisher=Cambridge University Press |isbn=978-0-521-64482-2}}</ref>

== Qishloq xo'jaligida ==

=== Ekinlarda ===
Insonlar dehqonchilik bilan shug'ullanishni boshlaganlarida, ekinlarning istalgan xususiyatlarini o'tkazish va istalmaganlarini chiqarib tashlash uchun [[Selektiv chatishtirish|selektiv chatishtirishdan]] (selective breeding) foydalanganlar. Selektiv chatishtirish [[Monokultura|monokulturalarga]] — deyarli bir xil genetikaga ega o'simliklardan iborat butun dalalarga olib keladi. Genetik xilma-xillikning kamligi yoki umuman yo'qligi ekinlarni keng tarqalgan kasalliklarga o'ta moyil qilib qo'yadi; bakteriyalar doimiy ravishda o'zgarib turadi va kasallik qo'zg'atuvchi bakteriya ma'lum bir genetik variatsiyaga hujum qilish uchun o'zgarganda, u turning katta qismini osonlikcha yo'q qilib yuborishi mumkin. Agar bakteriya hujum qilishga moslashgan genetik variatsiya insonlar tomonidan hosil olish uchun tanlab olingan nav bo'lsa, butun ekin nobud bo'ladi.<ref>{{cite journal|last1=King|first1=K. C.|last2=Lively|first2=C. M.|date=June 2012|title=Does genetic diversity limit disease spread in natural host populations?|journal=Heredity|volume=109|issue=4|pages=199–203|doi=10.1038/hdy.2012.33|pmc=3464021|pmid=22713998|bibcode=2012Hered.109..199K}}</ref>

XIX asrda Irlandiyada yuz bergan [[Buyuk ocharchilik (Irlandiya)|Buyuk ocharchilik]] qisman bioxilma-xillikning yetishmasligi tufayli kelib chiqqan. Yangi kartoshka o'simliklari urug'lanish natijasida emas, balki ona o'simlik bo'laklaridan ko'paytirilganligi sababli, genetik xilma-xillik rivojlanmaydi va butun ekin aslida bitta kartoshkaning kloni hisoblanadi. Bu esa uni epidemiyaga ayniqsa moyil qiladi. 1840-yillarda Irlandiya aholisining katta qismi oziq-ovqat sifatida kartoshkaga qaram edi. Ular asosan chirishga sabab bo'luvchi ''[[Phytophthora infestans]]'' nomli [[Oomitset|oomitsetga]] moyil bo'lgan «lumper» kartoshka navini ekishgan.<ref name="understandingEvolution">{{cite web |title=Monoculture and the Irish Potato Famine: cases of missing genetic variation |url=http://evolution.berkeley.edu/evolibrary/article/agriculture_02 |publisher=University of California Museum of Paleontology |access-date=8 May 2018}}</ref> Zamburug'simon organizm kartoshka hosilining katta qismini yo'q qildi va bir million kishining ochlikdan o'lishiga sabab bo'ldi.

Qishloq xo'jaligidagi genetik xilma-xillik nafaqat kasalliklar, balki [[o'txo'rlar]] (herbivores) bilan ham bog'liq. Yuqoridagi misolga o'xshab, monokulturali qishloq xo'jaligi butun maydon bo'ylab bir xil xususiyatlarni tanlab oladi. Agar ushbu [[genotip]] ma'lum o'txo'rlar uchun zaif bo'lsa, bu hosilning katta qismi yo'qolishiga olib kelishi mumkin.<ref name="pmid20662149">{{cite journal|author1=Matson, P. A.|author2=Parton, W. J.|author3=Power, A. G.|author4=Swift, M. J.|title=Agricultural intensification and ecosystem properties|url=https://archive.org/details/sim_science_1997-07-25_277_5325/page/504|journal=Science|volume=277|issue=5325|pages=504–9|date=July 1997|pmid=20662149|doi=10.1126/science.277.5325.504|citeseerx=10.1.1.484.4218}}</ref><ref>{{cite book |year=2002 |title=Introduction to Conservation Genetics |url=https://archive.org/details/introductiontoco0000fran |publisher=Cambridge University Press |author1=Frankham, Richard |author2=Ballou, Jonathan D. |author3=Briscoe, David A.}}</ref> Fermerlar buning oldini olish usullaridan biri sifatida [[Aralash ekish|aralash ekishdan]] (inter-cropping) foydalanadilar. O'txo'rlar va ularning afzal ko'rgan xo'jayin o'simliklari o'rtasida to'siq sifatida qarindosh bo'lmagan yoki genetik jihatdan farq qiluvchi ekin qatorlarini ekish orqali fermer o'txo'rning butun maydon bo'ylab tarqalish qobiliyatini samarali ravishda kamaytiradi.<ref>{{cite book |last=Vandermeer |year=1992 |first=John H. |title=The ecology of intercropping |publisher=Cambridge University Press |name-list-style=vanc}}</ref><ref>{{cite journal|last=Risch|first=Stephen|name-list-style=vanc|title=The population dynamics of several herbivorous beetles in a tropical agroecosystem: the effect of intercropping corn, beans and squash in Costa Rica|url=https://archive.org/details/sim_journal-of-applied-ecology_1980-12_17_3/page/592|journal=Journal of Applied Ecology|volume=17|issue=3|year=1980|pages=593–611|doi=10.2307/2402639|jstor=2402639|bibcode=1980JApEc..17..593R}}</ref><ref>{{cite journal|last1=Tonhasca|first1=Athayde|last2=Byrne|first2=David N.|name-list-style=vanc|title=The effects of crop diversification on herbivorous insects: a meta-analysis approach.|url=https://archive.org/details/sim_ecological-entomology_1994-08_19_3/page/238|journal=Ecological Entomology|volume=19|issue=3|year=1994|pages=239–244|doi=10.1111/j.1365-2311.1994.tb00415.x|bibcode=1994EcoEn..19..239T|s2cid=85239204}}</ref>

=== Chorvachilikda ===
Chorva turlarining genetik xilma-xilligi turli muhitlarda va turli maqsadlarda [[chorvachilik]] (animal husbandry) bilan shug'ullanish imkonini beradi. U [[selektiv chatishtirish]] dasturlari uchun xomashyo vazifasini o'taydi va chorva populyatsiyalariga atrof-muhit sharoitlari o'zgarganda moslashishga imkon beradi.<ref name="FAO_2015">{{cite web |publisher=United Nations Food and Agriculture Organization |date=2015 |title=The Second Report on the State of the World's Animal Genetic Resources for Food and Agriculture. |url=http://www.fao.org/publications/sowangr/en/ |location=Rome |access-date=2018-05-08 |archive-date=2018-09-18 |archive-url=https://web.archive.org/web/20180918190600/http://www.fao.org/publications/sowangr/en}}</ref>

[[Oziq-ovqat va qishloq xo'jaligi uchun hayvonlarning genetik resurslari|Chorva bioxilma-xilligi]] [[Zot|zotlarning]] qirilib ketishi va [[genetik eroziya]] (genetic erosion)ning boshqa shakllari natijasida yo'qolishi mumkin. 2014-yil iyun holatiga ko'ra, Birlashgan Millatlar Tashkilotining Oziq-ovqat va qishloq xo'jaligi tashkiloti ([[Oziq-ovqat va qishloq xo'jaligi tashkiloti|FAO]]) tomonidan yuritiladigan Uy hayvonlari xilma-xilligi bo'yicha ma'lumot tizimida ([[DAD-IS]]) qayd etilgan 8 774 zotdan 17 foizi qirilib ketish xavfi ostida, 7 foizi esa allaqachon qirilib ketgan deb tasniflangan.<ref name="FAO_2015" /> Hozirgi kunda 2007-yilda Oziq-ovqat va qishloq xo'jaligi genetik resurslari bo'yicha komissiya homiyligida ishlab chiqilgan Hayvonlarning genetik resurslari bo'yicha global harakat rejasi mavjud bo'lib, u hayvonlarning genetik resurslarini boshqarish uchun asos va ko'rsatmalarni taqdim etadi.

Hayvonlarning genetik resurslarini saqlash muhimligi haqidagi xabardorlik vaqt o'tishi bilan ortib bormoqda. FAO [[oziq-ovqat va qishloq xo'jaligi uchun dunyo hayvonlari genetik resurslarining holati]] bo'yicha ikkita hisobotni nashr etdi. Ushbu hisobotlar global chorva xilma-xilligi va ularni boshqarish hamda saqlash qobiliyatining batafsil tahlillarini qamrab oladi.

== Virusli oqibatlar ==
Vaktsinalarni loyihalashda viruslardagi yuqori genetik xilma-xillik hisobga olinishi shart. Yuqori genetik xilma-xillik maqsadli vaktsinalarni yaratishda qiyinchilik tug'diradi va viruslarga vaktsina halokatliligiga qarshilik ko'rsatish uchun tez evolyutsiyaga uchrash imkonini beradi. Masalan, bezgak vaktsinalariga oqsil antijenlaridagi genetik xilma-xillikning yuqori darajasi ta'sir ko'rsatadi.<ref>{{cite journal|last=Frankham|first=Richard|title=Genetics and Extinction|url=https://archive.org/details/sim_biological-conservation_2005-11_126_2/page/131|journal=Biological Conservation|date=November 2005|volume=126|issue=2|pages=131–140|quote=The rate of evolutionary change (R) is determined primarily by the quantitative genetic variation|doi=10.1016/j.biocon.2005.05.002|bibcode=2005BCons.126..131F}}</ref> Bundan tashqari, [[OIV kichik turlari|OIV-1]] (HIV-1) genetik xilma-xilligi hozirda mavjud bo'lgan virus yuki va rezistentlik testlaridan foydalanishni cheklaydi.<ref>{{Cite journal|last1=Peeters|first1=M.|last2=Aghokeng|first2=A.F|last3=Delaporte|first3=E.|date=October 2010|title=Genetic diversity among human immunodeficiency virus-1 non-B subtypes in viral load and drug resistance assays|journal=Clinical Microbiology and Infection|volume=16|issue=10|pages=1525–1531|doi=10.1111/j.1469-0691.2010.03300.x|pmid=20649800|doi-access=free}}</ref>

[[Koronavirus]] populyatsiyalari [[mutatsiya]] va [[gomologik rekombinatsiya]] (homologous recombination) tufayli sezilarli evolyutsion xilma-xillikka ega.<ref>{{cite journal|last1=King|first1=K. C.|last2=Lively|first2=C. M.|date=June 2012|title=Does genetic diversity limit disease spread in natural host populations?|journal=Heredity|volume=109|issue=4|pages=199–203|doi=10.1038/hdy.2012.33|pmc=3464021|pmid=22713998|bibcode=2012Hered.109..199K}}</ref> Masalan, kasallangan bemorlardan olingan 86 ta SARS-CoV-2 koronavirus namunasini sekvenlash (ketma-ketligini aniqlash) natijasida 93 ta mutatsiya aniqlandi, bu esa sezilarli genetik xilma-xillik mavjudligini ko'rsatadi.<ref>{{cite book |year=2002 |title=Introduction to Conservation Genetics |url=https://archive.org/details/introductiontoco0000fran |publisher=Cambridge University Press |author1=Frankham, Richard |author2=Ballou, Jonathan D. |author3=Briscoe, David A.}}</ref> Koronavirus [[RNK virusi|RNK genomi]] nusxalanishi [[RNKga bog'liq RNK polimeraza]] (RNA-dependent RNA polymerase) tomonidan katalizlanadi. Nusxalanish jarayonida ushbu polimeraza shablonni almashtirishi mumkin, bu gomologik rekombinatsiyaning bir shaklidir.<ref>{{cite journal|last=Frankham|first=Richard|title=Genetics and Extinction|url=https://archive.org/details/sim_biological-conservation_2005-11_126_2/page/131|journal=Biological Conservation|date=November 2005|volume=126|issue=2|pages=131–140|quote=The rate of evolutionary change (R) is determined primarily by the quantitative genetic variation|doi=10.1016/j.biocon.2005.05.002|bibcode=2005BCons.126..131F}}</ref> Shuningdek, genetik xilma-xillikni hosil qiluvchi ushbu jarayon RNK genomining shikastlanishini bartaraf etish uchun moslashuv bo'lib ko'rinadi.<ref>{{cite book |last=Pullin |first=Andrew S. |date=2002 |title=Conservation biology |url=https://archive.org/details/conservationbiol0000pull |edition=1st |publisher=Cambridge University Press |isbn=978-0-521-64482-2}}</ref>

== Past genetik xilma-xillikni bartaraf etish ==
[[Fayl:Cheetah_genetic_diversity.jpg|thumb|[[Tanzaniya gepardi]].]]

=== Tabiiy yo'llar ===
[[Fayl:Plankton_collage.jpg|left|thumb|Plankton organizmlarining [[Fotomontaj|fotomontaji]].]]
Tabiatda genetik xilma-xillikni saqlash yoki oshirishning bir necha usullari mavjud. Okean [[Plankton|planktonlari]] orasida [[Virus|viruslar]] genetik siljish jarayoniga yordam beradi. Planktonni zararlaydigan okean viruslari o'z genlaridan tashqari boshqa organizmlarning genlarini ham tashiydi. Bir hujayraning genlarini o'z ichiga olgan virus boshqasini zararlaganda, keyingisining genetik tuzilishi o'zgaradi. Genetik tuzilishning bu doimiy o'zgarishi, murakkab va oldindan aytib bo'lmaydigan atrof-muhit o'zgarishlariga qaramay, plankton populyatsiyasini sog'lom saqlashga yordam beradi.<ref>{{cite journal|last1=King|first1=K. C.|last2=Lively|first2=C. M.|date=June 2012|title=Does genetic diversity limit disease spread in natural host populations?|journal=Heredity|volume=109|issue=4|pages=199–203|doi=10.1038/hdy.2012.33|pmc=3464021|pmid=22713998|bibcode=2012Hered.109..199K}}</ref>

[[Gepard|Gepardlar]] [[xavf ostidagi turlar]] hisoblanadi. Past genetik xilma-xillik va buning natijasida sperma sifatining yomonligi gepardlar uchun ko'payish va yashab qolishni qiyinlashtirdi. Bundan tashqari, gepardlarning atigi 5 foizi voyaga yetguniga qadar yashab qoladi.<ref>{{cite book |year=2002 |title=Introduction to Conservation Genetics |url=https://archive.org/details/introductiontoco0000fran |publisher=Cambridge University Press |author1=Frankham, Richard |author2=Ballou, Jonathan D. |author3=Briscoe, David A.}}</ref> Biroq, yaqinda urg'ochi gepardlarning bir to'da bolalari uchun bittadan ortiq erkak bilan juftlashishi mumkinligi aniqlandi. Ularda induktsiyalangan ovulyatsiya kuzatiladi, ya'ni urg'ochi har safar juftlashganda yangi tuxum ishlab chiqariladi. Ona bir nechta erkak bilan juftlashish orqali bitta nasldagi bolalar ichida genetik xilma-xillikni oshiradi.<ref>{{cite web |url=http://news.bbc.co.uk/2/hi/science/nature/6701515.stm |access-date=December 12, 2008 |title=Cheating cheetahs caught by DNA |author=Fildes, Jonathan |date=May 29, 2007 |work=BBC News}}</ref>

=== Inson aralashuvi ===
Genetik xilma-xillikni oshirish orqali turning yashovchanligini oshirishga qaratilgan urinishlar genetik qutqaruv deb ataladi. Masalan, [[Texas|Texasdan]] sakkizta pantera inbriding tufayli kamayib borayotgan va [[inbriding depressiyasi]] (inbreeding depression)dan aziyat chekayotgan [[Florida]] panterasi populyatsiyasiga kiritildi. Shu tariqa genetik o'zgaruvchanlik oshirildi va bu Florida panterasi populyatsiyasining sezilarli darajada o'sishiga olib keldi.<ref>{{Cite journal|last1=Pimm|first1=S. L.|last2=Dollar|first2=L.|last3=Bass|first3=O. L.|date=May 2006|title=The genetic rescue of the Florida panther|journal=Animal Conservation|volume=9|issue=2|pages=115–122|doi=10.1111/j.1469-1795.2005.00010.x|doi-access=free|bibcode=2006AnCon...9..115P}}</ref> Populyatsiyaning uzoq umr ko'rishini ta'minlash maqsadida turlarni qutqarish ishlarida yuqori genetik xilma-xillikni yaratish yoki saqlash muhim omil hisoblanadi.

== O'lchovlar ==
Populyatsiyaning genetik xilma-xilligini ba'zi oddiy o'lchovlar yordamida baholash mumkin.

* '''Gen xilma-xilligi''' — bu [[genom]] bo'ylab [[Polimorfizm (biologiya)#Genetika|polimorf]] lokuslar nisbati.
* '''[[Zigositalik#Populyatsiya genetikasida geterozigositalik|Geterozigositalik]]''' — populyatsiyadagi ma'lum bir lokus uchun geterozigota bo'lgan individlarning ulushi.
* '''Lokus boshiga allellar''' ham o'zgaruvchanlikni namoyish qilish uchun ishlatiladi.
* '''[[Nukleotid xilma-xilligi]]''' — bu populyatsiya ichidagi nukleotid polimorfizmlarining darajasi bo'lib, odatda mikro- va minisatellit ketma-ketliklari, mitoxondrial DNK<ref>{{Cite journal|last1=Kawabe|first1=K.|last2=Worawut|first2=R.|last3=Taura|first3=S.|last4=Shimogiri|first4=T.|last5=Nishida|first5=T.|last6=Okamoto|first6=S.|date=2014-01-01|title=Genetic Diversity of mtDNA D-loop Polymorphisms in Laotian Native Fowl Populations|journal=Asian-Australasian Journal of Animal Sciences|volume=27|issue=1|pages=19–23|doi=10.5713/ajas.2013.13443|pmc=4093284|pmid=25049921}}</ref> va [[Bir nukleotidli polimorfizm|bir nukleotidli polimorfizmlar]] (SNP) kabi molekulyar markerlar orqali o'lchanadi.

Bundan tashqari, allel chastotasi va populyatsiya hajmi kabi o'lchovlar asosida populyatsiyaning kelajagini bashorat qilish uchun stoxastik simulyatsiya dasturlari keng qo'llaniladi.<ref>{{Cite journal|last=Hoban|first=Sean|date=2014-04-30|title=An overview of the utility of population simulation software in molecular ecology|journal=Molecular Ecology|volume=23|issue=10|pages=2383–2401|doi=10.1111/mec.12741|pmid=24689878|doi-access=free|bibcode=2014MolEc..23.2383H}}</ref>

Genetik xilma-xillikni ham o'lchash mumkin. Genetik xilma-xillikni o'lchashning turli qayd etilgan usullari quyidagilarni o'z ichiga oladi:<ref>{{Cite web |last=diversity |first=measuring |title=measuring species diversity |url=https://www.webpages.uidaho.edu/range357/notes/diversity.pdf}}</ref>

* [[Turlar boyligi]] — turlar sonining o'lchovi
* [[Turlar mo'lligi]] — turlar miqdorining nisbiy o'lchovi
* Turlar zichligi — birlik maydondagi turlarning umumiy sonini baholash
== Manbalar ==
{{manbalar}}
[[Turkum:Biologik xilma-xillik]]
[[Turkum:Genetik tushunchalar]]
[[Turkum:Populyatsiya genetikasi]]