Genetic admixture explained

Genetic admixture occurs when previously isolated populations interbreed resulting in a population that is descended from multiple sources. It can occur between species, such as with hybrids, or within species, such as when geographically distant individuals migrate to new regions. It results in gene pool that is a mix of the source populations.^{[1] [2] [3]}

Examples

Climatic cycles facilitate genetic admixture in cold periods and genetic diversification in warm periods.^[4] Natural flooding can cause genetic admixture within populations of migrating fish species.^[5] Genetic admixture may have an important role for the success of populations that colonise a new area and interbreed with individuals of native populations.^[6]

Mapping

Admixture mapping is a method of gene mapping that uses a population of mixed ancestry (an admixed population) to find the genetic loci that contribute to differences in diseases or other phenotypes found between the different ancestral populations. The method is best applied to populations with recent admixture from two populations that were previously genetically isolated. The method attempts to correlate the degree of ancestry near a genetic locus with the phenotype or disease of interest. Genetic markers that differ in frequency between the ancestral populations are needed across the genome.^[7]

Admixture mapping is based on the assumption that differences in disease rates or phenotypes are due in part to differences in the frequencies of disease-causing or phenotype-causing genetic variants between populations. In an admixed population, these causal variants occur more frequently on chromosomal segments inherited from one or another ancestral population. The first admixture scans were published in 2005 and since then genetic contributors to a variety of disease and trait differences have been mapped.^[8] By 2010, high-density mapping panels had been constructed for African Americans, Latino/Hispanics, and Uyghurs.

See also

• Chloroplast capture
• Gene cluster
• Gene flow
• Haplogroup
• Human genetic variation
• Hybrid
• Hybrid vigor
• Interbreeding between archaic and modern humans
• Introgression
• Population groups in biomedicine

Further reading

• Book: Balding. Handbook of statistical genetics, Volume 1 . 2007 . Glossary of Genetic Terms . https://books.google.com/books?id=hFjNvMWBk14C&q=genetic+admixture+glossary&pg=PR37 . 978-0-470-05830-5 . John Wiley & Sons .
• Book: Foulkes . Applied Statistical Genetics With R: For Population-based Association Studies . Glossary of Terms . 28 April 2009 . https://books.google.com/books?id=gwW8jArHnwwC&q=genetic+admixture+glossary&pg=PT250. 978-0-387-89553-6 . 250. Springer .
• Book: Stone . Genes, culture, and human evolution: a synthesis . 2007 . Glossary of Terms . https://books.google.com/books?id=zdeWdF_NQhEC&pg=PA298 . 978-1-4051-5089-7 . Wiley . etal.
• Kolbe JJ, Glor RE, Schettino LR, Lara AC, Losos AL, Losos JB (2004) Genetic Variation Increases during Biological Invasion by a Cuban Lizard. Nature 431: 171-181
• Lenormand T (2002). Gene flow and the limits to natural selection. Trends in Ecology and Evolution. 17:183-189
• Shriner 2013, "Overview of Admixture Mapping"

Notes and References

1. Korunes . Katharine L. . Goldberg . Amy . Human genetic admixture . PLOS Genetics . Public Library of Science (PLoS) . 17 . 3 . 2021-03-11 . 1553-7404 . 10.1371/journal.pgen.1009374 . e1009374 . free . 7951803 .
2. Rius, M. . Darling, J.A. . How important is intraspecific genetic admixture to the success of colonising populations? . 2014 . Trends in Ecology & Evolution . 29 . 4 . 233−242 . 10.1016/j.tree.2014.02.003 . 24636862.
3. Yang . Melinda A. . Fu . Qiaomei . Insights into Modern Human Prehistory Using Ancient Genomes . Trends in Genetics . March 2018 . 34 . 3 . 184–196 6y . 10.1016/j.tig.2017.11.008 . 29395378.
4. Lv X, Cheng J, Meng Y, Chang Y, Xia L, Wen Z, Ge D, Liu S, Yang Q . 2018 . Disjunct distribution and distinct intraspecific diversification of Eothenomys melanogaster in South China . BMC Evolutionary Biology . 18 . 1 . 50 . 10.1186/s12862-018-1168-3 . 29636000 . 5894153 . free .
5. Jaisuk, C. . Senanan, W. . 2018 . Effects of landscape features on population genetic variation of a tropical stream fish, Stone lapping minnow, Garra cambodgiensis, in the upper Nan River drainage basin, northern Thailand . PeerJ . 6 . e4487. 10.7717/peerj.4487 . 29568710 . 5845392 . free .
6. Kolbe JJ, Larson A, Losos JB, de Queiroz K . 2008 . Admixture determines genetic diversity and population differentiation in the biological invasion of a lizard species . Biology Letters . 4 . 4 . 434−437 . 10.1098/rsbl.2008.0205 . 18492644 . 2610154.
7. Shriver . MD . etal . Skin pigmentation, biogeographical ancestry and admixture mapping . Human Genetics . April 2003 . 112 . 4 . 387–99 . 10.1007/s00439-002-0896-y . 12579416 . 7877572 .
8. 10.1146/annurev-genom-082509-141523 . Winkler . C. A. . Nelson . G. W. . Smith . M. W. . Admixture mapping comes of age . Annu Rev Genom Hum Genet . 11 . 65–89 . 2010 . 20594047 . 7454031 .