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Encyclopedia > Gene flow
Part of the Biology series on
Evolution
Mechanisms and processes

Adaptation
Genetic drift
Gene flow
Mutation
Natural selection
Speciation For the song by Girls Aloud see Biology (song) Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle Biology (from Greek: Βιολογία - βίος, bio, life; and λόγος, logos, speech lit. ... This article is about evolution in biology. ... Image File history File links Tree_of_life. ... For other uses, see Adaptation (disambiguation). ... In population genetics, genetic drift is the statistical effect that results from the influence that chance has on the success of alleles (variants of a gene). ... For linguistic mutation, see Apophony. ... For other uses, see Natural selection (disambiguation). ... Charles Darwins first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837) Speciation is the evolutionary process by which new biological species arise. ...

Research and history

Evidence
Evolutionary history of life
History
Modern synthesis
Social effect / Objections While on board HMS Beagle, Charles Darwin collected numerous specimens, many new to science, which supported his later theory of evolution by natural selection. ... The evolutionary history of life and the origin of life are fields of ongoing geological and biological research. ... Evolutionary thought has roots in antiquity as philosophical ideas conceived during the Ancient Greek and Roman eras, but until the 18th century, biological thought was dominated by essentialism, the idea that living forms are static and unchanging in time. ... The modern evolutionary synthesis refers to a set of ideas from several biological specialities that were brought together to form a unified theory of evolution accepted by the great majority of working biologists. ... The theory of transmutation had early origins in the speculations and hypotheses of Erasmus Darwin, and Jean-Baptiste Lamarck. ... There have been numerous objections to evolution since alternative evolutionary ideas came to be hotly debated around the start of the nineteenth century. ...

Evolutionary biology fields

Cladistics
Ecological genetics
Evolutionary development
Human evolution
Molecular evolution
Phylogenetics
Population genetics
It has been suggested that Clade be merged into this article or section. ... Ecological genetics is the study of genetics (itself a field of biology) from an ecological perspective. ... Evolutionary developmental biology (evolution of development or informally, evo-devo) is a field of biology that compares the developmental processes of different animals in an attempt to determine the ancestral relationship between organisms and how developmental processes evolved. ... For the history of humans on Earth, see History of the world. ... Molecular evolution is the process of the genetic material in populations of organisms changing over time. ... Phylogenetic groups, or taxa, can be monophyletic, paraphyletic, or polyphyletic. ... Population genetics is the study of the distribution of and change in allele frequencies under the influence of the four evolutionary forces: natural selection, genetic drift, mutation, and migration. ...

Biology Portal · v  d  e 

In population genetics, gene flow (also known as gene migration) is the transfer of alleles of genes from one population to another. Population genetics is the study of the distribution of and change in allele frequencies under the influence of the four evolutionary forces: natural selection, genetic drift, mutation, and migration. ... An allele is any one of a number of alternative forms of the same gene occupying a given locus (position) on a chromosome. ... For other uses, see Gene (disambiguation). ...


Migration into or out of a population may be responsible for a marked change in allele frequencies (the proportion of members carrying a particular variant of a gene). Immigration may also result in the addition of new genetic variants to the established gene pool of a particular species or population. Allele frequency is a term of population genetics that is used in characterizing the genetic diversity of a species population, or equivalently the richness of its gene pool. ... The gene pool of a species or a population is the complete set of unique alleles that would be found by inspecting the genetic material of every living member of that species or population. ...


There are a number of factors that affect the rate of gene flow between different populations. One of the most significant factors is mobility, as greater mobility of an individual tends to give it greater migratory potential. Animals tend to be more mobile than plants, although pollen and seeds may be carried great distances by animals or wind.


Maintained gene flow between two populations can also lead to a combination of the two gene pools, reducing the genetic variation between the two groups. It is for this reason that gene flow strongly acts against speciation, by recombining the gene pools of the groups, and thus, repairing the developing differences in genetic variation that would have led to full speciation and creation of daughter species. Charles Darwins first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837) Speciation is the evolutionary process by which new biological species arise. ...

Contents

Barrier to gene flow

Physical barriers to gene flow are usually, but not always, natural. They may include impassable mountain ranges, oceans, or vast deserts. In some cases, they can be artificial, man-made barriers, such as the Great Wall of China, which has hindered the gene flow of native plant populations[1]. Samples of the same species which grow on either side have been shown to have developed genetic differences, because there is no gene flow to provide recombination of the gene pools. The Great Wall of China (simplified Chinese: ; traditional Chinese: ; pinyin: ; literally Long wall) or (simplified Chinese: ; traditional Chinese: ; pinyin: ; literally The long wall of 10,000 Li (里)[1]) is a series of stone and earthen fortifications in China, built, rebuilt, and maintained between the 5th century BC and the 16th...


Barriers to gene flow need not always to be physical. Species can live in the same environment, yet show very limited gene flow due to limited hybridization or hybridization yielding unfit hybrids.


Gene flow in humans

Gene flow has been observed in humans. For example, in the United States, gene flow was observed between a white European population and a black West African population, which were recently brought together. In West Africa, where malaria is prevalent, the Duffy antigen provides some resistance to the disease, and this allele is thus present in nearly all of the West African population. In contrast, Europeans have either the allele Fya or Fyb, because malaria is almost non-existent. By measuring the frequencies of the West African and European groups, scientists found that the allele frequencies became mixed in each population because of movement of individuals. It was also found that this gene flow between European and West African groups is much greater in the Northern U.S. than in the South.[citation needed] Human beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. ... Malaria is a vector-borne infectious disease caused by protozoan parasites. ... Discovery In 1950 the Duffy antigen was discovered in a multiply transfused hemophiliac in whose serum contained the first example of anti-Fya. ...


Gene flow between species

Gene flow can occur between species, either through hybridization or gene transfer from bacteria or virus to new hosts. This article is about a biological term. ...


Gene transfer, defined as the movement of genetic material across species boundaries, which includes horizontal gene transfer, antigenic shift, and reassortment is sometimes an important source of genetic variation. Viruses can transfer genes between species [2]. Bacteria can incorporate genes from other dead bacteria, exchange genes with living bacteria, and can exchange plasmids across species boundaries [3]. "Sequence comparisons suggest recent horizontal transfer of many genes among diverse species including across the boundaries of phylogenetic "domains". Thus determining the phylogenetic history of a species can not be done conclusively by determining evolutionary trees for single genes." [4] Transformation is the genetic alteration of a cell resulting from the introduction, uptake and expression of foreign genetic material (DNA or RNA). ... Horizontal gene transfer (HGT), also Lateral gene transfer (LGT), is any process in which an organism transfers genetic material to another cell that is not its offspring. ... Antigenic shift is the process by which two different strains of influenza combine to form a new subtype having a mixture of the surface antigens of the two original strains. ... Reassortment is the exchange of DNA between viruses inside a host cell. ... Figure 1: Illustration of a bacterium with plasmids enclosed showing chromosomal DNA and plasmids. ... For other uses, see Gene (disambiguation). ... For other uses, see Species (disambiguation). ... A phylogeny (or phylogenesis) is the origin and evolution of a set of organisms, usually of a species. ...


Biologist Gogarten suggests "the original metaphor of a tree no longer fits the data from recent genome research". Biologists [should] instead use the metaphor of a mosaic to describe the different histories combined in individual genomes and use the metaphor of an intertwined net to visualize the rich exchange and cooperative effects of horizontal gene transfer. [5]


"Using single genes as phylogenetic markers, it is difficult to trace organismal phylogeny in the presence of HGT [horizontal gene transfer]. Combining the simple coalescence model of cladogenesis with rare HGT [horizontal gene transfer] events suggest there was no single last common ancestor that contained all of the genes ancestral to those shared among the three domains of life. Each contemporary molecule has its own history and traces back to an individual molecule cenancestor. However, these molecular ancestors were likely to be present in different organisms at different times." [6] For other uses, see Gene (disambiguation). ... In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... Coalescence is the process by which two or more droplets (or bubbles) merge during contact to form a single daughter droplet (or bubble). ... Cladogenesis is an evolutionary splitting event in which each branch and its smaller branches is a clade; an evolutionary mechanism and a process of adaptive evolution that leads to the development of a greater variety of animals or plants. ... Dad does not seem too surprised; perhaps this has happened to him before! Last Common Ancestor (LCA) is the most recent common ancestor of two populations that came to be separated by a species barrier. ... This article is about life in general. ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ...


Genetic pollution

Main article: Genetic pollution

Purebred, naturally-evolved, region-specific, wild species can be threatened with extinction in a big way[2] through the process of genetic pollution i.e. uncontrolled hybridization, introgression and genetic swamping which leads to homogenization or replacement of local genotypes as a result of either a numerical and/or fitness advantage of introduced plant or animal[3]. Nonnative species can bring about a form of extinction of native plants and animals by hybridization and introgression either through purposeful introduction by humans or through habitat modification, bringing previously isolated species into contact. These phenomena can be especially detrimental for rare species coming into contact with more abundant ones where the abundant ones can interbreed with them swamping the entire rarer gene pool creating hybrids thus driving the entire original purebred native stock to complete extinction. Attention has to be focused on the extent of this under appreciated problem that is not always apparent from morphological (outward appearance) observations alone. Some degree of gene flow may be a normal, evolutionarily constructive process, and all constellations of genes and genotypes cannot be preserved however, hybridization with or without introgression may, nevertheless, threaten a rare species' existence[4][5]. Genetic pollution, genetic contamination or genetic swamping happens when original set of naturally evolved (wild) region specific genes / gene pool of wild animals and plants become hybridized with domesticated and feral varieties or with the genes of other nonnative wild species or subspecies from neighboring or far away regions. ... For other uses, see Species (disambiguation). ... Genetic pollution, genetic contamination or genetic swamping happens when original set of naturally evolved (wild) region specific genes / gene pool of wild animals and plants become hybridized with domesticated and feral varieties or with the genes of other nonnative wild species or subspecies from neighboring or far away regions. ... In genetics, hybridisation is the process of mixing different species or varieties of organisms. ... Introgression is a term used in genetics, particularly plant genetics, to describe the movement of a gene from one species into the gene pool of another by backcrossing an interspecific hybrid with one of its parents. ... The genotype is the specific genetic makeup (the specific genome) of an individual, usually in the form of DNA. It codes for the phenotype of that individual. ... Fitness (often denoted in population genetics models) is a central concept in evolutionary theory. ... The term morphology in biology refers to the outward appearance (shape, structure, colour, pattern) of an organism or taxon and its component parts. ... For other uses, see Gene (disambiguation). ... The genotype is the specific genetic makeup (the specific genome) of an individual, usually in the form of DNA. It codes for the phenotype of that individual. ...


Models of gene flow

Models of gene flow can be derived from population genetics, e.g. Sewall Wright's neighborhood model, Wright's island model and the stepping stone model. Population genetics is the study of the distribution of and change in allele frequencies under the influence of the four evolutionary forces: natural selection, genetic drift, mutation, and migration. ... Sewall Green Wright ForMemRS (December 21, 1889 – March 3, 1988) was an American geneticist known for his influential work on evolutionary theory. ...


Gene flow mitigation

When cultivating genetically modified (GM) plants or livestock, it becomes necessary to prevent "genetic pollution" i.e. their genetic modification from reaching other conventionally hybridized or wild native plant and animal populations by using gene flow mitigation usually through unintentional cross pollination and crossbreeding. Reasons to limit gene flow may include biosafety or agricultural co-existence, in which GM and non-GM cropping systems work side by side. Elements of genetic engineering Genetic engineering, recombinant DNA technology, genetic modification/manipulation (GM) and gene splicing are terms that are applied to the direct manipulation of an organisms genes. ... Sheep are commonly bred as livestock. ... Genetic pollution, genetic contamination or genetic swamping happens when original set of naturally evolved (wild) region specific genes / gene pool of wild animals and plants become hybridized with domesticated and feral varieties or with the genes of other nonnative wild species or subspecies from neighboring or far away regions. ... Cross pollination is a form of pollination in which pollen from one plant pollinates another. ... Crossbreeding is the process of creating hybrids (also known as crossbreeds, or a description of the lineage of that which has undergone hybridization. ... Biosafety: prevention of large-scale loss of biological integrity, focusing both on ecology and human health. ... In the context of agriculture and food and feed production, co-existence means using cropping systems with and without genetically modified organisms (GMOs) in parallel. ...


Scientists in several large research programmes are investigating methods of limiting gene flow in plants. Among these programmes are Transcontainer, which investigates methods for biocontainment, SIGMEA, which focuses on the biosafety of genetically modified plants, and Co-Extra, which studies the co-existence of GM and non-GM product chains. Biological containment (or biocontainment) describes measures aimed at preventing genetically modified organisms (GMOs) and their transgenes from spreading into the environment (for containment methods in closed research environments, see Biosafety level). ... Co-Extra is a EU-funded research programme on co-existence and traceability of genetically modified crops and their edible derivatives. ...


Generally, there are three approaches to gene flow mitigation: keeping the genetic modification out of the pollen, preventing the formation of pollen, and keeping the pollen inside the flower.

  • The first approach requires transplastomic plants. In transplastomic plants, the modified DNA is not situated in the cell's nucleus but is present in plastids, which are cellular compartments outside the nucleus. An example for plastids are chloroplasts, in which photosynthesis occurs. In some plants, the pollen does not contain plastids and, consequently, any modification located in plastids cannot be transmitted by the pollen.
  • The second approach relies on male sterile plants. Male sterile plants are unable to produce functioning flowers and therefore cannot release viable pollen. Cytoplasmic male sterile plants are known to produce higher yields. Therefore, researchers are trying to introduce this trait to genetically modified crops.
  • The third approach works by preventing the flowers from opening. This trait is called cleistogamy and occurs naturally in some plants. Cleistogamous plants produce flowers which either open only partly or not at all. However, it remains unclear how reliable cleistogamy is for gene flow mitigation: a Co-Extra research project on rapeseed investigating the matter has published preliminary results which cast doubt on the attainment of a high degree of reliability.

The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... Plant cells with visible chloroplasts. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Photosynthesis splits water to liberate O2 and fixes CO2 into sugar The leaf is the primary site of photosynthesis in plants. ... SEM image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis). ... Male sterility is defined as the failure of plants to produce functional anthers, pollen, or male gametes. ... Cleistogamy describes the trait of certain plants to propagate by using non-opening, self-pollinating flowers. ...

See also

This article does not cite any references or sources. ... Genetic pollution, genetic contamination or genetic swamping happens when original set of naturally evolved (wild) region specific genes / gene pool of wild animals and plants become hybridized with domesticated and feral varieties or with the genes of other nonnative wild species or subspecies from neighboring or far away regions. ... Wikipedia does not yet have an article with this exact name. ...

External links

  • Co-Extra research on gene flow mitigation
  • Transcontainer research on biocontainment
  • SIGMEA research on the biosafety of GMOs: http://sigmea.dyndns.org

References

  1. ^ Su, H et al. (2003) "The Great Wall of China: a physical barrier to gene flow?." Heredity, Volume 9 Pages 212-219
  2. ^ Hybridization and Introgression; Extinctions; from "The evolutionary impact of invasive species; by H. A. Mooney and E. E. Cleland" Proc Natl Acad Sci U S A. 2001 May 8; 98(10): 5446–5451. doi: 10.1073/pnas.091093398. Proc Natl Acad Sci U S A, v.98(10); May 8, 2001, The National Academy of Sciences
  3. ^ Glossary: definitions from the following publication: Aubry, C., R. Shoal and V. Erickson. 2005. Grass cultivars: their origins, development, and use on national forests and grasslands in the Pacific Northwest. USDA Forest Service. 44 pages, plus appendices.; Native Seed Network (NSN), Institute for Applied Ecology, 563 SW Jefferson Ave, Corvallis, OR 97333, USA
  4. ^ EXTINCTION BY HYBRIDIZATION AND INTROGRESSION; by Judith M. Rhymer , Department of Wildlife Ecology, University of Maine, Orono, Maine 04469, USA; and Daniel Simberloff, Department of Biological Science, Florida State University, Tallahassee, Florida 32306, USA; Annual Review of Ecology and Systematics, November 1996, Vol. 27, Pages 83-109 (doi: 10.1146/annurev.ecolsys.27.1.83), [1]
  5. ^ Genetic Pollution from Farm Forestry using eucalypt species and hybrids; A report for the RIRDC/L&WA/FWPRDC; Joint Venture Agroforestry Program; by Brad M. Potts, Robert C. Barbour, Andrew B. Hingston; September 2001; RIRDC Publication No 01/114; RIRDC Project No CPF - 3A; ISBN 0 642 58336 6; ISSN 1440-6845; Australian Government, Rural Industrial Research and Development Corporation
  • Su, H et al. (2003) "The Great Wall of China: a physical barrier to gene flow?." Heredity, Volume 9 Pages 212-219
While on board HMS Beagle, Charles Darwin collected numerous specimens, many new to science, which supported his later theory of evolution by natural selection. ... For other uses, see Adaptation (disambiguation). ... Macroevolution refers to evolution that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population. ... Microevolution is the occurrence of small-scale changes in allele frequencies in a population, over a few generations, also known as change at or below the species level. ... Charles Darwins first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837) Speciation is the evolutionary process by which new biological species arise. ... Population genetics is the study of the distribution of and change in allele frequencies under the influence of the four evolutionary forces: natural selection, genetic drift, mutation, and migration. ... For other uses, see Natural selection (disambiguation). ... In population genetics, genetic drift is the statistical effect that results from the influence that chance has on the success of alleles (variants of a gene). ... For linguistic mutation, see Apophony. ... Evolutionary developmental biology (evolution of development or informally, evo-devo) is a field of biology that compares the developmental processes of different animals in an attempt to determine the ancestral relationship between organisms and how developmental processes evolved. ... We dont have an article called Phenotypic plasticity Start this article Search for Phenotypic plasticity in. ... Norms of reaction for two genotypes. ... Many organisms consist of modules, both anatomically and in their metabolism. ... A number of different Markov models of DNA sequence evolution have been proposed. ... The evolution of sex is a major puzzle in modern evolutionary biology. ... Enquiry into the evolution of ageing aims to explain why almost all living things weaken and die with age. ... The nature and origins of hominid intelligence is a much-studied and much-debated topic, of natural interest to humans as the most successful and intelligent hominid species. ... Diagram of major stages in the eyes evolution. ... Plant evolution is an aspect of the study of biological evolution, involving predominantly the evolution of plants suited to live on land, the greening of the various land masses by the filling of their niches with land plants, and the diversification of the groups of land plants. ... The evolutionary history of life and the origin of life are fields of ongoing geological and biological research. ... For the history of humans on Earth, see History of the world. ... Anagenesis is the progressive evolution of species involving a change in gene frequency in an entire population rather than a cladogenetic branching event. ... Catagenesis is an archaic term from evolutionary biology referring to evolutionary directions that were considered retrogressive. ... Cladogenesis is an evolutionary splitting event in which each branch and its smaller branches is a clade; an evolutionary mechanism and a process of adaptive evolution that leads to the development of a greater variety of animals or plants. ... Evolutionary thought has roots in antiquity as philosophical ideas conceived during the Ancient Greek and Roman eras, but until the 18th century, biological thought was dominated by essentialism, the idea that living forms are static and unchanging in time. ... For other people of the same surname, and places and things named after Charles Darwin, see Darwin. ... The 1859 edition of On the Origin of Species First published in 1859, The Origin of Species (full title On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life) by British naturalist Charles Darwin is one of the pivotal... The modern evolutionary synthesis refers to a set of ideas from several biological specialities that were brought together to form a unified theory of evolution accepted by the great majority of working biologists. ... The gene-centered view of evolution, gene selection theory or selfish gene theory holds that natural selection acts through differential survival of competing genes, increasing the frequency of those alleles whose phenotypic effects successfully promote their own propagation. ... This article is about life in general. ... Ecological genetics is the study of genetics (itself a field of biology) from an ecological perspective. ... Molecular evolution is the process of the genetic material in populations of organisms changing over time. ... Phylogenetic groups, or taxa, can be monophyletic, paraphyletic, or polyphyletic. ... Biological systematics is the study of the diversity of life on the planet earth, both past and present, and the relationships among living things through time. ... This is a list of topics in evolutionary biology and evolution. ... Life on Earth  â€¢  â€¢  | Axis scale: millions of years ago. ...

  Results from FactBites:
 
Gene flow Summary (1816 words)
Gene flow is also a method by which advantageous genes or alleles can be spread throughout a population, making them more common and more likely to remain within the population.
Gene flow (also known as migration) is the transfer of genes from one population to another.
Gene flow has been observed in humans, for example in the United States, where a white European population and a fl West African population were recently brought together.
Gene Flow in Alfalfa (2397 words)
Pollen flow was estimated as 1.39, 0.32, 0.07, 0.00% at 500, 1000, 1500 and 2000 ft, respectively.
The importance of unintended gene flow between adjacent seed fields and to feral alfalfa is receiving renewed attention as the U. alfalfa seed industry prepares for commercialization of the first transgenic alfalfa varieties.
Total gene flow potential is estimated by multiplying the %RR seed observed in the trap plots by an adjustment factor of 1.72 (i.
  More results at FactBites »

 
 

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