Admin: 1 версия импортирована

2025-11-13T17:59:03Z

1 версия импортирована

← Предыдущая версия		Версия от 17:59, 13 ноября 2025
(нет различий)

ru>Trappist the monk: cite repair (Category:CS1 maint: article number as page number);

2025-09-24T00:31:40Z

cite repair (Category:CS1 maint: article number as page number);

Новая страница

{{Main|Natural selection}}
'''Genetic viability''' is the ability of the genes present to allow a cell, organism or population to survive and reproduce.<ref name=":1">{{cite book| vauthors = Hartl DL |url= https://oxford.universitypressscholarship.com/view/10.1093/oso/9780198862291.001.0001/oso-9780198862291 |title=A Primer of Population Genetics and Genomics|date=2020 |publisher=Oxford University Press |isbn=978-0-19-886229-1|edition=4th |doi=10.1093/oso/9780198862291.001.0001 }}</ref><ref>{{cite journal | vauthors = Luo L, Zhang YM, Xu S | title = A quantitative genetics model for viability selection | journal = Heredity | volume = 94 | issue = 3 | pages = 347–355 | date = March 2005 | pmid = 15536483 | doi = 10.1038/sj.hdy.6800615 | doi-access = free }}</ref> The term is generally used to mean the chance or ability of a [[population]] to avoid the problems of [[inbreeding]].<ref name=":1" /> Less commonly genetic viability can also be used in respect to a single cell or on an individual level.<ref name=":1" />

Inbreeding depletes [[heterozygosity]] of the genome, meaning there is a greater chance of identical alleles at a locus.<ref name=":1" /> When these alleles are non-beneficial, homozygosity could cause problems for genetic viability.<ref name=":1" /> These problems could include effects on the individual [[Fitness (biology)|fitness]] (higher mortality, slower growth, more frequent developmental defects, reduced mating ability, lower fecundity, greater susceptibility to disease, lowered ability to withstand stress, reduced intra- and inter-specific competitive ability) or effects on the entire population fitness (depressed population growth rate, reduced regrowth ability, reduced ability to adapt to environmental change).<ref name=":2">{{cite journal| vauthors = Lacy RC |date=1997-05-21|title=Importance of Genetic Variation to the Viability of Mammalian Populations |journal=Journal of Mammalogy |volume=78|issue=2|pages=320–335|doi=10.2307/1382885 |jstor=1382885|doi-access=free}}</ref> See [[Inbreeding depression]]. When a population of plants or animals loses their genetic viability, their chance of going extinct increases.<ref name=":3">{{cite journal | vauthors = Robert A | title = Find the weakest link. A comparison between demographic, genetic and demo-genetic metapopulation extinction times | journal = BMC Evolutionary Biology | volume = 11 | issue = 1 | page = 260 | date = September 2011 | pmid = 21929788 | pmc = 3185286 | doi = 10.1186/1471-2148-11-260 | doi-access = free | bibcode = 2011BMCEE..11..260R }}</ref>

== Necessary conditions ==
To be genetically viable, a population of plants or animals requires a certain amount of [[genetic diversity]] and a certain [[population size]].<ref>{{cite journal| vauthors = Tensen L, van Vuuren BJ, Du Plessis C, Marneweck DG |date=2019-06-01|title=African wild dogs: Genetic viability of translocated populations across South Africa |journal=Biological Conservation|language=en|volume=234|pages=131–9|doi=10.1016/j.biocon.2019.03.033 |bibcode=2019BCons.234..131T |hdl=2263/70709|hdl-access=free}}</ref> For long-term genetic viability, the population size should consist of enough breeding pairs to maintain genetic diversity.<ref>{{cite journal| vauthors = Cegelski CC, Waits LP, Anderson NJ, Flagstad O, Strobeck C, Kyle CJ |date=2006-04-01|title=Genetic diversity and population structure of wolverine (Gulo gulo) populations at the southern edge of their current distribution in North Americawith implications for genetic viability |journal=Conservation Genetics|language=en|volume=7|issue=2|pages=197–211|doi=10.1007/s10592-006-9126-9 |bibcode=2006ConG....7..197C |s2cid=44217068}}</ref> The precise [[effective population size]] can be calculated using a [[minimum viable population]] analysis.<ref>{{cite journal | vauthors = Nunney L, Campbell KA | title = Assessing minimum viable population size: Demography meets population genetics | journal = Trends in Ecology & Evolution | volume = 8 | issue = 7 | pages = 234–9 | date = July 1993 | pmid = 21236157 | doi = 10.1016/0169-5347(93)90197-W | bibcode = 1993TEcoE...8..234N }}</ref> Higher genetic diversity and a larger population size will decrease the negative effects of [[genetic drift]] and inbreeding in a population.<ref name=":2" /> When adequate measures have been met, the genetic viability of a population will increase.<ref name="pmid17513881">{{cite journal | vauthors = Zhang B, Li M, Zhang Z, Goossens B, Zhu L, Zhang S, Hu J, Bruford MW, Wei F | display-authors = 6 | title = Genetic viability and population history of the giant panda, putting an end to the "evolutionary dead end"? | journal = Molecular Biology and Evolution | volume = 24 | issue = 8 | pages = 1801–10 | date = August 2007 | pmid = 17513881 | doi = 10.1093/molbev/msm099 | doi-access = free }}</ref>

== Causes for decrease ==
[[File:Population bottleneck.svg|thumb|250x250px|Population bottleneck can decrease genetic viability leading to possible extinction <ref name=":2" />]]
The main cause of a decrease in genetic viability is loss of [[habitat]].<ref name=":3" /><ref>{{cite journal | vauthors = Vonholdt BM, Stahler DR, Smith DW, Earl DA, Pollinger JP, Wayne RK | title = The genealogy and genetic viability of reintroduced Yellowstone grey wolves | journal = Molecular Ecology | volume = 17 | issue = 1 | pages = 252–74 | date = January 2008 | pmid = 17877715 | doi = 10.1111/j.1365-294X.2007.03468.x | bibcode = 2008MolEc..17..252V | s2cid = 9222840 }}</ref><ref>{{cite book |title=Agroforestry and biodiversity conservation in tropical landscapes|date=2004|publisher=Island Press|last=Schroth |first=G. |isbn=1-4237-6551-6|location=Washington|pages=290–314|oclc=65287651}}</ref> This loss can occur because of, for example [[urbanization]] or deforestation causing [[habitat fragmentation]].<ref name=":3" /> Natural events like earthquakes, floods or fires can also cause loss of habitat.<ref name=":3" /> Eventually, loss of habitat could lead to a [[population bottleneck]].<ref name=":2" /> In a small population, the risk of inbreeding will increase drastically which could lead to a decrease in genetic viability.<ref name=":2" /><ref name=":3" /><ref>{{cite book| vauthors = Young AG, Clarke GM, Clarke GM, Cowlishaw G |url=https://books.google.com/books?id=hk452JHmPrcC&q=population+bottleneck+genetic+viability&pg=PP1|title=Genetics, Demography and Viability of Fragmented Populations|date=2000-10-12|publisher=Cambridge University Press|isbn=978-0-521-79421-3 }}</ref> If they are specific in their diets, this can also lead to habitat isolation and reproductive constraints, leading to greater population bottleneck, and decrease in genetic viability.<ref name="pmid17513881" /> Traditional [[artificial propagation]] can also lead to decreases in genetic viability in some species.<ref>{{cite journal | vauthors = Reisenbichler RB, Rubin SP |title=Genetic changes from artificial propagation of Pacific salmon affect the productivity and viability of supplemented populations |journal=ICES Journal of Marine Science |date=August 1, 1999 |volume=56 |issue=4 |pages=459–466|doi=10.1006/jmsc.1999.0455 |doi-access=free |bibcode=1999ICJMS..56..459R }}</ref><ref>{{cite journal | vauthors = McClure MM, Utter FM, Baldwin C, Carmichael RW, Hassemer PF, Howell PJ, Spruell P, Cooney TD, Schaller HA, Petrosky CE | display-authors = 6 | title = Evolutionary effects of alternative artificial propagation programs: implications for viability of endangered anadromous salmonids | journal = Evolutionary Applications | volume = 1 | issue = 2 | pages = 356–75 | date = May 2008 | pmid = 25567637 | pmc = 3352443 | doi = 10.1111/j.1752-4571.2008.00034.x | bibcode = 2008EvApp...1..356M }}</ref>

===Genetic viability of particular wolf populations===

A small highly [[inbreeding|inbred]] population of gray wolves (''Canis lupus'') residing in [[Isle Royale National Park]], Michigan, USA has been undergoing population decline and is nearing extinction.<ref name = Robinson2019>{{cite journal |vauthors=Robinson JA, Räikkönen J, Vucetich LM, Vucetich JA, Peterson RO, Lohmueller KE, Wayne RK |title=Genomic signatures of extensive inbreeding in Isle Royale wolves, a population on the threshold of extinction |journal=Sci Adv |volume=5 |issue=5 |article-number=eaau0757 |date=May 2019 |pmid=31149628 |pmc=6541468 |doi=10.1126/sciadv.aau0757 |bibcode=2019SciA....5..757R }}</ref> These gray wolves have been experiencing severe [[inbreeding depression]] primarily determined by the [[zygosity|homozygous]] expression of strongly deleterious recessive [[mutation]]s leading to decreased genetic viability.<ref name = Robinson2019/><ref>{{cite journal |vauthors=Robinson JA, Räikkönen J, Vucetich LM, Vucetich JA, Peterson RO, Lohmueller KE, Wayne RK |title=Genomic signatures of extensive inbreeding in Isle Royale wolves, a population on the threshold of extinction |journal=Sci Adv |volume=5 |issue=5 |article-number=eaau0757 |date=May 2019 |pmid=31149628 |pmc=6541468 |doi=10.1126/sciadv.aau0757 |bibcode=2019SciA....5..757R }}</ref> Reduced genetic viability due to severe inbreeding was expressed as reduced reproduction and survival as well as specific defects such as malformed vertebrae, probable cataracts, syndactyly, an unusual "rope tail," and anomalous fur phenotypes. A separate inbred Scandinavian population of gray wolves (''Canis lupus''), also suffering from loss of genetic viability, is experiencing inbreeding depression likely due to the homozygous expression of deleterious recessive mutations.<ref name = Robinson2019/>

== Population conservation ==
Habitat protection is associated with more allelic richness and heterozygosity than in unprotected habitats.<ref name=":0" /> Reduced habitat fragmentation and increased landscape permeability can promote allelic richness by facilitating gene flow between populations that are isolated or smaller.<ref name=":0">{{cite journal | vauthors = Dellinger JA, Gustafson KD, Gammons DJ, Ernest HB, Torres SG | title = Minimum habitat thresholds required for conserving mountain lion genetic diversity | journal = Ecology and Evolution | volume = 10 | issue = 19 | pages = 10687–96 | date = October 2020 | pmid = 33072289 | doi = 10.1002/ece3.6723 | pmc = 7548186 | doi-access = free | bibcode = 2020EcoEv..1010687D }}</ref>

The minimum viable population needed to maintain genetic viability is where the loss of genetic variation because of small population size ([[genetic drift]]) is equal to genetic variation gained through [[mutation]].<ref>{{cite journal| vauthors = Traill LW, Brook BW, Frankham RR, Bradshaw CJ |date=January 2010|title=Pragmatic population viability targets in a rapidly changing world|journal=Biological Conservation|volume=143|issue=1|pages=28–34|doi=10.1016/j.biocon.2009.09.001|bibcode=2010BCons.143...28T }}</ref> When the numbers of one sex is too low, there may be a need for crossbreeding to maintain viability.<ref>{{cite journal| vauthors = Piyasatian N, Kinghorn BP |date=2003|title=Balancing genetic diversity, genetic merit and population viability in conservation programmes |journal=Journal of Animal Breeding and Genetics |volume=120|issue=3|pages=137–149|doi=10.1046/j.1439-0388.2003.00383.x }}</ref>

== Analyzing ==
When genetic viability seems to be decreasing within a population, a [[population viability analysis]] (PVA) can be done to assess the risk of extinction of this species.<ref name=":4">{{cite journal| vauthors = Menges ES |date=1990|title=Population Viability Analysis for an Endangered Plant |journal=Conservation Biology|language=en|volume=4|issue=1|pages=52–62|doi=10.1111/j.1523-1739.1990.tb00267.x|bibcode=1990ConBi...4...52M |issn=0888-8892}}</ref><ref>{{cite book | vauthors = Beissinger SR, McCullough DR |title=Population viability analysis|date=2002|publisher=University of Chicago Press|isbn=0-226-04177-8 |oclc=48100035}}</ref><ref>{{cite journal| vauthors = Boyce MS |date=1992-11-01|title=Population Viability Analysis |journal=Annual Review of Ecology and Systematics|language=en|volume=23|issue=1|pages=481–497|doi=10.1146/annurev.es.23.110192.002405|issn=0066-4162}}</ref> The result of a PVA could determine whether further action is needed regarding the preservation of a species.<ref name=":4" />

== Applications ==
Genetic viability is applied by wildlife management staff in zoos, aquariums or other such ex situ habitats.<ref name=":5" /> They use the knowledge of the animals' genetics, usually through their pedigrees, to calculate the PVA and manage the population viability.<ref name=":5">{{cite journal | vauthors = Lacy RC | title = Lessons from 30 years of population viability analysis of wildlife populations | journal = Zoo Biology | volume = 38 | issue = 1 | pages = 67–77 | date = January 2019 | pmid = 30585658 | doi = 10.1002/zoo.21468 }}</ref>

== References ==
{{Reflist|30em}}

[[Category:Genetics]]

Genetic viability - История изменений

Admin: 1 версия импортирована

ru>Trappist the monk: cite repair (Category:CS1 maint: article number as page number);