Population bottleneck

Last updated
Population bottleneck followed by recovery or extinction Population bottleneck.svg
Population bottleneck followed by recovery or extinction

A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as genocide, speciocide, widespread violence or intentional culling. Such events can reduce the variation in the gene pool of a population; thereafter, a smaller population, with a smaller genetic diversity, remains to pass on genes to future generations of offspring. Genetic diversity remains lower, increasing only when gene flow from another population occurs or very slowly increasing with time as random mutations occur. [1] [ self-published source ] This results in a reduction in the robustness of the population and in its ability to adapt to and survive selecting environmental changes, such as climate change or a shift in available resources. [2] Alternatively, if survivors of the bottleneck are the individuals with the greatest genetic fitness, the frequency of the fitter genes within the gene pool is increased, while the pool itself is reduced.

Contents

The genetic drift caused by a population bottleneck can change the proportional random distribution of alleles and even lead to loss of alleles. The chances of inbreeding and genetic homogeneity can increase, possibly leading to inbreeding depression. Smaller population size can also cause deleterious mutations to accumulate. [3]

Population bottlenecks play an important role in conservation biology (see minimum viable population size) and in the context of agriculture (biological and pest control). [4]

Minimum viable population size

In conservation biology, minimum viable population (MVP) size helps to determine the effective population size when a population is at risk for extinction. [5] [6] The effects of a population bottleneck often depend on the number of individuals remaining after the bottleneck and how that compares to the minimum viable population size.

Founder effects

A slightly different form of bottleneck can occur if a small group becomes reproductively (e.g., geographically) separated from the main population, such as through a founder event, e.g., if a few members of a species successfully colonize a new isolated island, or from small captive breeding programs such as animals at a zoo. Alternatively, invasive species can undergo population bottlenecks through founder events when introduced into their invaded range. [7]

Examples

Humans

According to a 1999 model, a severe population bottleneck, or more specifically a full-fledged speciation, occurred among a group of Australopithecina as they transitioned into the species known as Homo erectus two million years ago. It is believed that additional bottlenecks must have occurred since Homo erectus started walking the Earth, but current archaeological, paleontological, and genetic data are inadequate to give much reliable information about such conjectured bottlenecks. [8] Nonetheless, a 2023 genetic analysis discerned such a human ancestor population bottleneck of a possible 100,000 to 1000 individuals "around 930,000 and 813,000 years ago [which] lasted for about 117,000 years and brought human ancestors close to extinction." [9] [10]

A 2005 study from Rutgers University theorized that the pre-1492 native populations of the Americas are the descendants of only 70 individuals who crossed the land bridge between Asia and North America. [11]

The Neolithic Y-chromosome bottleneck refers to a period around 5000 BC where the diversity in the male y-chromosome dropped precipitously, to a level equivalent to reproduction occurring with a ratio between men and women of 1:17. [12] Discovered in 2015 [13] the research suggests that the reason for the bottleneck was not a reduction in the number of males, but a drastic decrease in the percentage of males with reproductive success.

Toba catastrophe theory

The controversial Toba catastrophe theory, presented in the late 1990s to early 2000s, suggested that a bottleneck of the human population occurred approximately 75,000 years ago, proposing that the human population was reduced to perhaps 10,000–30,000 individuals [14] when the Toba supervolcano in Indonesia erupted and triggered a major environmental change. Parallel bottlenecks were proposed to exist among chimpanzees, gorillas, rhesus macaques, orangutans and tigers. [15] The hypothesis was based on geological evidence of sudden climate change and on coalescence evidence of some genes (including mitochondrial DNA, Y-chromosome DNA and some nuclear genes) [16] and the relatively low level of genetic variation in humans. [14]

However, subsequent research, especially in the 2010s, appeared to refute both the climate argument and the genetic argument. Recent research shows the extent of climate change was much smaller than believed by proponents of the theory. [17]

In 2000, a Molecular Biology and Evolution paper suggested a transplanting model or a 'long bottleneck' to account for the limited genetic variation, rather than a catastrophic environmental change. [8] This would be consistent with suggestions that in sub-Saharan Africa numbers could have dropped at times as low as 2,000, for perhaps as long as 100,000 years, before numbers began to expand again in the Late Stone Age. [18]

Other animals

YearAmerican
bison (est)
Before 149260,000,000
1890750
2000360,000

European bison, also called wisent (Bison bonasus), faced extinction in the early 20th century. The animals living today are all descended from 12 individuals and they have extremely low genetic variation, which may be beginning to affect the reproductive ability of bulls. [19]

The population of American bison (Bison bison) fell due to overhunting, nearly leading to extinction around the year 1890, though it has since begun to recover (see table).

Overhunting pushed the northern elephant seal to the brink of extinction by the late 19th century. Although they have made a comeback, the genetic variation within the population remains very low. Northern Elephant Seal, San Simeon2.jpg
Overhunting pushed the northern elephant seal to the brink of extinction by the late 19th century. Although they have made a comeback, the genetic variation within the population remains very low.

A classic example of a population bottleneck is that of the northern elephant seal, whose population fell to about 30 in the 1890s. Although it now numbers in the hundreds of thousands, the potential for bottlenecks within colonies remains. Dominant bulls are able to mate with the largest number of females—sometimes as many as 100. With so much of a colony's offspring descended from just one dominant male, genetic diversity is limited, making the species more vulnerable to diseases and genetic mutations.

The golden hamster is a similarly bottlenecked species, with the vast majority of domesticated hamsters descended from a single litter found in the Syrian desert around 1930, and very few wild golden hamsters remain.

An extreme example of a population bottleneck is the New Zealand black robin, of which every specimen today is a descendant of a single female, called Old Blue. The Black Robin population is still recovering from its low point of only five individuals in 1980.

The genome of the giant panda shows evidence of a severe bottleneck about 43,000 years ago. [20] There is also evidence of at least one primate species, the golden snub-nosed monkey, that also suffered from a bottleneck around this time. An unknown environmental event is suspected to have caused the bottlenecks observed in both of these species. The bottlenecks likely caused the low genetic diversity observed in both species.

Other facts can sometimes be inferred from an observed population bottleneck. Among the Galápagos Islands giant tortoises—themselves a prime example of a bottleneck—the comparatively large population on the slopes of the Alcedo volcano is significantly less diverse than four other tortoise populations on the same island. DNA analyses date the bottleneck to around 88,000 years before present (YBP). [21] About 100,000 YBP the volcano erupted violently, deeply burying much of the tortoise habitat in pumice and ash.

Another example can be seen in the greater prairie chickens, which were prevalent in North America until the 20th century. In Illinois alone, the number of greater prairie chickens plummeted from over 100 million in 1900 to about 46 in 1998. [22] These declines in population were the result of hunting and habitat destruction, but the random consequences have also caused a great loss in species diversity. DNA analysis comparing the birds from 1990 and mid-century shows a steep genetic decline in recent decades. Management of the greater prairie chickens now includes genetic rescue efforts including the translocation prairie chickens between leks to increase each populations genetic diversity. [22]

Population bottlenecking poses a major threat to the stability of species populations as well. Papilio homerus is the largest butterfly in the Americas and is endangered according to the IUCN. The disappearance of a central population poses a major threat of population bottleneck. The remaining two populations are now geographically isolated and the populations face an unstable future with limited remaining opportunity for gene flow. [23]

Genetic bottlenecks exist in cheetahs. [24] [25]

Selective breeding

Bottlenecks also exist among pure-bred animals (e.g., dogs and cats: pugs, Persian) because breeders limit their gene pools by a few (show-winning) individuals for their looks and behaviors. The extensive use of desirable individual animals at the exclusion of others can result in a popular sire effect.

Selective breeding for dog breeds caused constricting breed-specific bottlenecks. [26] These bottlenecks have led to dogs having an average of 2–3% more genetic loading than gray wolves. [27] The strict breeding programs and population bottlenecks have led to the prevalence of diseases such as heart disease, blindness, cancers, hip dysplasia, and cataracts. [26]

Selective breeding to produce high-yielding crops has caused genetic bottlenecks in these crops and has led to genetic homogeneity. [28] This reduced genetic diversity in many crops could lead to broader susceptibility to new diseases or pests, which threatens global food security. [29]

Plants

Research showed that there is incredibly low, nearly undetectable amounts of genetic diversity in the genome of the Wollemi pine (Wollemia nobilis). [30] The IUCN found a population count of 80 mature individuals and about 300 seedlings and juveniles in 2011, and previously, the Wollemi pine had fewer than 50 individuals in the wild. [31] The low population size and low genetic diversity indicates that the Wollemi pine went through a severe population bottleneck.

A population bottleneck was created in the 1970s through the conservation efforts of the endangered Mauna Kea silversword (Argyroxiphium sandwicense ssp. sandwicense). [32] The small natural population of silversword was augmented through the 1970s with outplanted individuals. All of the outplanted silversword plants were found to be first or subsequent generation offspring of just two maternal founders. The low amount of polymorphic loci in the outplanted individuals led to the population bottleneck, causing the loss of the marker allele at eight of the loci.

See also

Related Research Articles

<span class="mw-page-title-main">Inbreeding</span> Reproduction by closely related organisms

Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and other consequences that may arise from expression of deleterious recessive traits resulting from incestuous sexual relationships and consanguinity. Animals avoid incest only rarely.

Small populations can behave differently from larger populations. They are often the result of population bottlenecks from larger populations, leading to loss of heterozygosity and reduced genetic diversity and loss or fixation of alleles and shifts in allele frequencies. A small population is then more susceptible to demographic and genetic stochastic events, which can impact the long-term survival of the population. Therefore, small populations are often considered at risk of endangerment or extinction, and are often of conservation concern.

Population genetics is a subfield of genetics that deals with genetic differences within and among populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as adaptation, speciation, and population structure.

Phylogeography is the study of the historical processes that may be responsible for the past to present geographic distributions of genealogical lineages. This is accomplished by considering the geographic distribution of individuals in light of genetics, particularly population genetics.

<span class="mw-page-title-main">Gene flow</span> Transfer of genetic variation from one population to another

In population genetics, gene flow is the transfer of genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent allele frequencies and therefore can be considered a single effective population. It has been shown that it takes only "one migrant per generation" to prevent populations from diverging due to drift. Populations can diverge due to selection even when they are exchanging alleles, if the selection pressure is strong enough. Gene flow is an important mechanism for transferring genetic diversity among populations. Migrants change the distribution of genetic diversity among populations, by modifying allele frequencies. High rates of gene flow can reduce the genetic differentiation between the two groups, increasing homogeneity. For this reason, gene flow has been thought to constrain speciation and prevent range expansion by combining the gene pools of the groups, thus preventing the development of differences in genetic variation that would have led to differentiation and adaptation. In some cases dispersal resulting in gene flow may also result in the addition of novel genetic variants under positive selection to the gene pool of a species or population

<span class="mw-page-title-main">Founder effect</span> Effect in population genetics

In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1942, using existing theoretical work by those such as Sewall Wright. As a result of the loss of genetic variation, the new population may be distinctively different, both genotypically and phenotypically, from the parent population from which it is derived. In extreme cases, the founder effect is thought to lead to the speciation and subsequent evolution of new species.

<span class="mw-page-title-main">Genetic diversity</span> Total number of genetic characteristics in a species

Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species, it ranges widely from the number of species to differences within species and can be attributed to the span of survival for a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary.

<i>Argyroxiphium</i> Genus of plants

Argyroxiphium is a small genus of plants in the family Asteraceae. Its members are known by the common names silversword or greensword due to their long, narrow leaves and the silvery hairs on some species. The silverswords belong to a larger radiation of over 50 species, including the physically different genera Dubautia and Wilkesia. This grouping is often referred to as the silversword alliance. Botanist P. H. Raven referred to this radiation as "the best example of adaptive radiation in plants".

In population genetics and population ecology, population size is a countable quantity representing the number of individual organisms in a population. Population size is directly associated with amount of genetic drift, and is the underlying cause of effects like population bottlenecks and the founder effect. Genetic drift is the major source of decrease of genetic diversity within populations which drives fixation and can potentially lead to speciation events.

<span class="mw-page-title-main">Conservation genetics</span> Interdisciplinary study of extinction avoidance

Conservation genetics is an interdisciplinary subfield of population genetics that aims to understand the dynamics of genes in a population for the purpose of natural resource management, conservation of genetic diversity, and the prevention of species extinction. Scientists involved in conservation genetics come from a variety of fields including population genetics, research in natural resource management, molecular ecology, molecular biology, evolutionary biology, and systematics. The genetic diversity within species is one of the three fundamental components of biodiversity, so it is an important consideration in the wider field of conservation biology.

Genetic viability is the ability of the genes present to allow a cell, organism or population to survive and reproduce. The term is generally used to mean the chance or ability of a population to avoid the problems of inbreeding. Less commonly genetic viability can also be used in respect to a single cell or on an individual level.

<span class="mw-page-title-main">Molecular ecology</span> Field of evolutionary biology

Molecular ecology is a field of evolutionary biology that is concerned with applying molecular population genetics, molecular phylogenetics, and more recently genomics to traditional ecological questions. It is virtually synonymous with the field of "Ecological Genetics" as pioneered by Theodosius Dobzhansky, E. B. Ford, Godfrey M. Hewitt, and others. These fields are united in their attempt to study genetic-based questions "out in the field" as opposed to the laboratory. Molecular ecology is related to the field of conservation genetics.

Inbreeding depression is the reduced biological fitness that has the potential to result from inbreeding. The loss of genetic diversity that is seen due to inbreeding, results from small population size. Biological fitness refers to an organism's ability to survive and perpetuate its genetic material. Inbreeding depression is often the result of a population bottleneck. In general, the higher the genetic variation or gene pool within a breeding population, the less likely it is to suffer from inbreeding depression, though inbreeding and outbreeding depression can simultaneously occur.

<span class="mw-page-title-main">Human genetic variation</span> Genetic diversity in human populations

Human genetic variation is the genetic differences in and among populations. There may be multiple variants of any given gene in the human population (alleles), a situation called polymorphism.

<span class="mw-page-title-main">Masatoshi Nei</span> Japanese-American geneticist (1931–2023)

Masatoshi Nei was a Japanese-born American evolutionary biologist.

A genetic isolate is a population of organisms with little genetic mixing with other organisms within the same species due to geographic isolation or other factors that prevent reproduction. Genetic isolates form new species through an evolutionary process known as speciation. All modern species diversity is a product of genetic isolates and evolution.

<span class="mw-page-title-main">Introduction to evolution</span> Non-technical overview of the subject of biological evolution

In biology, evolution is the process of change in all forms of life over generations, and evolutionary biology is the study of how evolution occurs. Biological populations evolve through genetic changes that correspond to changes in the organisms' observable traits. Genetic changes include mutations, which are caused by damage or replication errors in organisms' DNA. As the genetic variation of a population drifts randomly over generations, natural selection gradually leads traits to become more or less common based on the relative reproductive success of organisms with those traits.

Genetic monitoring is the use of molecular markers to (i) identify individuals, species or populations, or (ii) to quantify changes in population genetic metrics over time. Genetic monitoring can thus be used to detect changes in species abundance and/or diversity, and has become an important tool in both conservation and livestock management. The types of molecular markers used to monitor populations are most commonly mitochondrial, microsatellites or single-nucleotide polymorphisms (SNPs), while earlier studies also used allozyme data. Species gene diversity is also recognized as an important biodiversity metric for implementation of the Convention on Biological Diversity.

<span class="mw-page-title-main">Mauna Kea silversword</span> Subspecies of flowering plant

Argyroxiphium sandwicense subsp. sandwicense, the Mauna Kea silversword, is a highly endangered flowering plant endemic to the island of Hawaiʻi of Hawaii. It is the "crown jewel" of the volcanic mountain Mauna Kea, from which it derives its English name. The Hawaiian name is ʻahinahina; it applies to silverswords more broadly. The Mauna Kea silversword was once common on the volcano, and extraordinary conservation efforts are being made to preserve the species.

Genetic rescue is seen as a mitigation strategy designed to restore genetic diversity and reduce extinction risks in small, isolated and frequently inbred populations. It is largely implemented through translocation, a type of demographic rescue and technical migration that adds individuals to a population to prevent its potential extinction. This demographic rescue may be similar to genetic rescue, as each increase population size and/or fitness. This overlap in meaning has led some researchers to consider a more detailed definition for each type of rescue that details 'assessment and documentation of pre- and post-translocation genetic ancestry'. Not every example of genetic rescue is clearly successful and the current definition of genetic rescue does not mandate that the process result in a 'successful' outcome. Despite an ambiguous definition, genetic rescue is viewed positively, with many perceived successes.

References

  1. ↑ William R. Catton, Jr. "Bottleneck: Humanity's Impending Impasse" Xlibris Corporation, 2009. 290 pp. ISBN   978-1-4415-2241-2 [ page needed ][ self-published source ]
  2. ↑ Lande, R. (1988). "Genetics and demography in biological conservation". Science. 241 (4872): 1455–1460. Bibcode:1988Sci...241.1455L. doi:10.1126/science.3420403. PMID   3420403.
  3. ↑ Lynch, M.; Conery, J.; Burger, R. (1995). "Mutation accumulation and the extinction of small populations". The American Naturalist. 146 (4): 489–518. doi:10.1086/285812. S2CID   14762497.
  4. ↑ Hufbauer RA, Bogdanowicz SM, Harrison RG (February 2004). "The population genetics of a biological control introduction: mitochondrial DNA and microsatellie variation in native and introduced populations of Aphidus ervi, a parasitoid wasp". Molecular Ecology. 13 (2): 337–48. doi:10.1046/j.1365-294X.2003.02084.x. PMID   14717891. S2CID   45796650.
  5. ↑ Gilpin, M.E.; Soulé, M.E. (1986). "Minimum viable populations: The processes of species extinctions". In Soulé, Michael E. (ed.). Conservation biology: The science of scarcity and diversity. Sunderland Mass: Sinauer Associates. pp. 13–34. ISBN   978-0-87893-794-3.
  6. ↑ Soulé, Michael E., ed. (1987). Viable populations for conservation . Cambridge: Cambridge Univ. Press. ISBN   978-0-521-33657-4.[ page needed ]
  7. ↑ Lee, C. E. (2002). Evolutionary genetics of invasive species. Trends in ecology & evolution, 17(8), 386-391.
  8. 1 2 Hawks J, Hunley K, Lee SH, Wolpoff M (January 2000). "Population bottlenecks and Pleistocene human evolution". Molecular Biology and Evolution. 17 (1): 2–22. doi: 10.1093/oxfordjournals.molbev.a026233 . PMID   10666702.
  9. ↑ Zimmer, Carl (31 August 2023). "Humanity's Ancestors Nearly Died Out, Genetic Study Suggests - The population crashed following climate change about 930,000 years ago, scientists concluded. Other experts aren't convinced by the analysis". the New York Times . Archived from the original on 31 August 2023. Retrieved 2 September 2023.
  10. ↑ Hu, Wangjie; et al. (31 August 2023). "Genomic inference of a severe human bottleneck during the Early to Middle Pleistocene transition". Science . 381 (6661): 979–984. Bibcode:2023Sci...381..979H. doi:10.1126/science.abq7487. PMID   37651513. S2CID   261396309. Archived from the original on 1 September 2023. Retrieved 2 September 2023.
  11. ↑ "North America Settled by Just 70 People, Study Concludes". LiveScience. 2005-05-25. Retrieved 2010-04-01.
  12. ↑ Starr, Michelle (31 May 2018). "Something Weird Happened to Men 7,000 Years Ago, And We Finally Know Why". sciencealert.com. Retrieved 12 September 2023.
  13. ↑ Karmin; et al. (2015). "A recent bottleneck of Y chromosome diversity coincides with a global change in culture". Genome Research. 25 (4): 459–466. doi: 10.1101/gr.186684.114 . PMC   4381518 . PMID   25770088.
  14. 1 2 Dawkins, Richard (2004). "The Grasshopper's Tale". The Ancestor's Tale, A Pilgrimage to the Dawn of Life. Boston: Houghton Mifflin Company. p. 416. ISBN   0-297-82503-8.
  15. ↑ Prothero, Donald R. (2013-08-01). Reality Check: How Science Deniers Threaten Our Future. Indiana University Press. p. 263. ISBN   9780253010360.
  16. ↑ Ambrose SH (June 1998). "Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans". Journal of Human Evolution. 34 (6): 623–51. doi:10.1006/jhev.1998.0219. PMID   9650103. S2CID   33122717.
  17. ↑ "Doubt over 'volcanic winter' after Toba super-eruption. 2013". Phys.org. 2013-05-02. Retrieved 2015-10-31.
  18. ↑ Behar DM, Villems R, Soodyall H, et al. (May 2008). "The dawn of human matrilineal diversity". American Journal of Human Genetics. 82 (5): 1130–40. doi:10.1016/j.ajhg.2008.04.002. PMC   2427203 . PMID   18439549.
  19. ↑ Luenser, K.; Fickel, J.; Lehnen, A.; Speck, S.; Ludwig, A. (2005). "Low level of genetic variability in European bisons (Bison bonasus) from the Bialowieza National Park in Poland". European Journal of Wildlife Research. 51 (2): 84–7. doi:10.1007/s10344-005-0081-4. S2CID   34102378.
  20. ↑ Zhang, Ya-Ping; Wang, Xiao-xia; Ryder, Oliver A.; Li, Hai-Peng; Zhang, He-Ming; Yong, Yange; Wang, Peng-yan (2002). "Genetic diversity and conservation of endangered animal species". Pure and Applied Chemistry. 74 (4): 575–84. doi: 10.1351/pac200274040575 . S2CID   13945117.
  21. ↑ Beheregaray LB, Ciofi C, Geist D, Gibbs JP, Caccone A, Powell JR (October 2003). "Genes record a prehistoric volcano eruption in the Galápagos". Science. 302 (5642): 75. doi:10.1126/science.1087486. PMID   14526072. S2CID   39102858.
  22. 1 2 Mussmann, S. M.; Douglas, M. R.; Anthonysamy, W. J. B.; Davis, M. A.; Simpson, S. A.; Louis, W.; Douglas, M. E. (February 2017). "Genetic rescue, the greater prairie chicken and the problem of conservation reliance in the Anthropocene". Royal Society Open Science. 4 (2): 160736. doi:10.1098/rsos.160736. ISSN   2054-5703. PMC   5367285 . PMID   28386428.
  23. ↑ Lehnert, Matthew S.; Kramer, Valerie R.; Rawlins, John E.; Verdecia, Vanessa; Daniels, Jaret C. (2017-07-10). "Jamaica's Critically Endangered Butterfly: A Review of the Biology and Conservation Status of the Homerus Swallowtail (Papilio (Pterourus) homerus Fabricius)". Insects. 8 (3): 68. doi: 10.3390/insects8030068 . PMC   5620688 . PMID   28698508.
  24. ↑ Menotti-Raymond, M.; O'Brien, S. J. (Apr 1993). "Dating the genetic bottleneck of the African cheetah". Proc Natl Acad Sci U S A. 90 (8): 3172–6. Bibcode:1993PNAS...90.3172M. doi: 10.1073/pnas.90.8.3172 . PMC   46261 . PMID   8475057.
  25. ↑ O'Brien, S.; Roelke, M.; Marker, L; Newman, A; Winkler, C.; Meltzer, D; Colly, L; Evermann, J.; Bush, M; Wildt, D. (March 22, 1985). "Genetic basis for species vulnerability in the cheetah" (PDF). Science. 227 (4693): 1428–1434. Bibcode:1985Sci...227.1428O. doi:10.1126/science.2983425. PMID   2983425. Archived from the original (PDF) on 2006-05-07.
  26. 1 2 Lindblad-Toh, K.; Wade, C. M.; Mikkelsen, T. S.; Karlsson, E. K. (2005). "Genome sequence, comparative analysis and haplotype structure of the domestic dog". Nature. 438 (7069): 803–819. Bibcode:2005Natur.438..803L. doi: 10.1038/nature04338 . PMID   16341006.
  27. ↑ Marsden, C. D.; Ortega-Del Vecchyo, D.; O'Brien, D. P.; et al. (2016). "Bottlenecks and selective sweeps during domestication have increased deleterious genetic variation in dogs". Proceedings of the National Academy of Sciences. 113 (1): 152–157. Bibcode:2016PNAS..113..152M. doi: 10.1073/pnas.1512501113 . PMC   4711855 . PMID   26699508.
  28. ↑ National Research Council. (1972). Genetic vulnerability of major crops. National Academies.
  29. ↑ Hyten, D. L.; Song, Q.; Zhu, Y.; et al. (2006). "Impacts of genetic bottlenecks on soybean genome diversity". Proceedings of the National Academy of Sciences. 103 (45): 16666–16671. Bibcode:2006PNAS..10316666H. doi: 10.1073/pnas.0604379103 . PMC   1624862 . PMID   17068128.
  30. ↑ Peakall, R.; Ebert, D.; Scott, L. J.; Meagher, P. F.; Offord, C. A. (2003). "Comparative genetic study confirms exceptionally low genetic variation in the ancient and endangered relictual conifer, Wollemia nobilis (Araucariaceae)". Molecular Ecology. 12 (9): 2331–2343. doi:10.1046/j.1365-294X.2003.01926.x. PMID   12919472. S2CID   35255532.
  31. ↑ Thomas, P. (2011). "Wollemia nobilis". The IUCN Red List of Threatened Species. doi: 10.2305/IUCN.UK.2011-2.RLTS.T34926A9898196.en .
  32. ↑ Robichaux, R. H.; Friar, E. A.; Mount, D. W. (1997). "Molecular Genetic Consequences of a Population Bottleneck Associated with Reintroduction of the Mauna Kea Silversword (Argyroxiphium sandwicense ssp. sandwicense [Asteraceae])". Conservation Biology. 11 (5): 1140–1146. doi:10.1046/j.1523-1739.1997.96314.x. S2CID   83819334.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.