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Genetic admixture occurs when individuals from two or more previously separated populations begin interbreeding. Admixture results in the introduction of new genetic lineages into a population. It has been known to slow local adaptation by introducing foreign, unadapted genotypes (known as gene swamping). It also prevents
speciationSpeciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...
by homogenizeing populations.
Genetic admixture often occurs when a geographic barrier separating populations ,such as a river or
isthmusAn isthmus is a narrow strip of land connecting two larger land areas usually with waterforms on either side.Canals are often built through isthmuses where they may be particularly advantageous to create a shortcut for marine transportation...
, is removed or when anthropogenic activities result in movement of populations (for example invasive species).
One example of genetic admixture resulting from the introduction of an invasive species is provided by the Cuban
brown anoleThe Brown Anole is a lizard native to Cuba and the Bahamas. It has been widely introduced elsewhere, and is now found in Florida and as far north as southern Georgia, Texas, Taiwan, Hawaii, Southern California, and other Caribbean islands.This species is highly invasive...
. Several isolated populations of this species exist in the native range of
CubaThe Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
. However in the introduced range of
FloridaFlorida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, these populations freely interbreed, forming an admixed population.
See also
- Racial admixture
- Gene flow
In population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...
- Hybrid
- Admixture mapping
Admixture mapping is a method of gene mapping that makes use of a population of mixed ancestry to find the genetic loci that contribute to differences in diseases or other phenotypes found between the different ancestral populations...