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Genetic admixture occurs when previously diverged or isolated genetic lineages mix. Admixture results in the introduction of new genetic lineages into a population.


Examples

Climatic cycles facilitate genetic admixture in cold periods and genetic diversification in warm periods. Natural
flood A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrolog ...
ing can cause genetic admixture within populations of migrating fish species. Genetic admixture may have an important role for the success of populations that colonise a new area and
interbreed In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in ...
with individuals of native populations.


Mapping

Admixture mapping is a method of
gene mapping Gene mapping describes the methods used to identify the locus of a gene and the distances between genes. Gene mapping can also describe the distances between different sites within a gene. The essence of all genome mapping is to place a c ...
that uses a
population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...
of mixed ancestry (an admixed population) to find the genetic loci that contribute to differences in diseases or other
phenotypes In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological prope ...
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. 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. By 2010, high-density mapping panels had been constructed for African Americans, Latino/Hispanics, and Uyghurs.


See also

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Chloroplast capture Chloroplast capture is an evolutionary process through which inter-species hybridization and subsequent backcrosses yield a plant with new genetic combination of nuclear and chloroplast genomes. For instance, 1) species A's (having chloroplast gen ...
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Gene cluster A gene family is a set of homologous genes within one organism. A gene cluster is a group of two or more genes found within an organism's DNA that encode similar polypeptides, or proteins, which collectively share a generalized function and ar ...
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Gene flow In population genetics, gene flow (also known as gene migration or geneflow and allele 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 a ...
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Haplogroup A haplotype is a group of alleles in an organism that are inherited together from a single parent, and a haplogroup (haploid from the el, ἁπλοῦς, ''haploûs'', "onefold, simple" and en, group) is a group of similar haplotypes that share ...
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Human genetic variation 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. No two humans are genetically identical. Even m ...
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Hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two dif ...
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Hybrid vigor Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions o ...
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Interbreeding between archaic and modern humans There is evidence for interbreeding between archaic and modern humans during the Middle Paleolithic and early Upper Paleolithic. The interbreeding happened in several independent events that included Neanderthals and Denisovans, as well as sever ...
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Introgression Introgression, also known as introgressive hybridization, in genetics is the transfer of genetic material from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. Intro ...
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Population groups in biomedicine Race and health refers to how being identified with a specific race influences health. Race is a complex concept that has changed across chronological eras and depends on both self-identification and social recognition. In the study of race and ...


References


Further reading

* * * * 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"
{{Authority control Applied genetics Evolutionary biology concepts Genetic mapping Population genetics