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drift in Biological Definition

Evolution

... mechanisms: natural selection , genetic drift or changes in population structure ( gene flow ... 1.3.1 Natural selection 1.3.2 Genetic drift 1.3.3 Gene flow 1.4 Microevolution and ... the frequency of an allele: Genetic drift Gene flow Natural selection ...

Genetic drift

... Genetic drift is a mechanism of evolution that acts in ... and changing the diversity of the group. drift is observed most strongly in small populations ... 1 Allele frequencies 2 drift versus selection 3 ...

Hardy-Weinberg principle

... (or effectively so, so as to eliminate genetic drift ) sexually reproducing randomly mating ... , assortative mating , selection , or genetic drift . Assortative mating will only change the ... of those genes that are desired. Genetic drift is particularly active in small population sizes ...

Natural selection

... . Other mechanisms of evolution include genetic drift and gene flow . Mutations create the genetic ... into an offspring), gene flow and genetic drift are also important mechanisms. Competition ... evolution Fitness genetic drift negative selection selection ...

Neutral theory of molecular evolution

... The theory attributes a large role to genetic drift . Contents showTocToggle("show","hide") ... evolutionary change is the result of genetic drift acting on neutral alleles . A new allele arises ... that is, genes that are affected mostly by drift or mostly by selection depending on the effective ...

Antigenic shift

... may be highly dangerous. Antigenic shift is contrasted with antigenic drift which is the natural mutation over time of known strains of influenza ... things, in a more general sense) to evade the immune system. Antigenic drift occurs in all types of influenza including influenza A, B and C. Antigenic ...

Molecular evolution

... allele (variant of a gene ): Mutation detailed above. Genetic drift describes changes in gene frequency that cannot be ascribed to selective ... . See also Neutral theory of molecular evolution Genetic drift Parsimony Selection Molecular clock References ...

Population genetics

... influence of the four evolutionary forces: natural selection , genetic drift , mutation and migration . It also takes account of population ... disagreements and a controversy about the relative roles of selection and drift continued for much of the century between the Americans and the British. ...

Sewall Wright

... synthesis . In a long career, he invented much of the theory of genetic drift (also known as the "Sewall Wright effect") and developed the inbreeding ... ), and he emphasized the importance of the interaction of genetic drift and natural selection in determining the outcome of evolution . He ...

Allele frequency

... lead to changes in the distribution and frequencies of alleles -- in other words, to evolution . Besides selection, these forces include genetic drift , mutation and migration . Compare genotype frequency . Example If there are ten individuals in a population and at a given locus there ...

Biology

... its driving force: natural selection . ( Alfred Russell Wallace is commonly recognized as the co-discoverer of this concept). Genetic drift was embraced as an additional mechanism in the so-called modern synthesis . The evolutionary history of a species —which tells the ...

Diffusion

... . Charge carriers (usually electrons ) move randomly in the absence of an electric field . When an electric field is applied, carriers drift preferentially in the field, causing a net current. The rate of transport is governed by the electrical conductivity of the conductor and the ...

Ewens's sampling formula

... n is small by comparison to the size of the whole population, and (2) the population is in statistical equilibrium under mutation and genetic drift and the role of selection at the locus in question is negligible, and (3) every mutant allele is novel. This is a probability distribution on ...

Extinction

... weaknesses. However, it is sometimes possible for a deleterious mutation to be spread throughout a population through the effect of genetic drift . A diverse or "deep" gene pool gives a population a higher chance of surviving an adverse change in conditions. Effects that cause or reward a ...

Fitness landscape

... rates this picture is somewhat simplistic. A population may not be able to climb a very sharp peak if the mutation rate is too high, or it may drift away from a peak it had already found. The process of drifting away from a peak is often referred to as Muller's ratchet . Fitness landscapes ...

Gene pool

... is said to be polymorphic with respect to that gene or locus. When no variation exists, it is labelled monomorphic . See also genetic drift small population size population genetics For the guitarist named Gene Pool , see Greg Flesch . ...

Genetics

... the distribution of and change in allele frequencies of genes under the influence of the four evolutionary forces: natural selection , genetic drift , mutation and migration . It is the theory that attempts to explain such phenomena as adaptation and speciation . The related subfield of ...

Isozyme

... unimportant part of the enzyme, for example a long way from the active site then the mutation may be selectively neutral and subject to genetic drift . (3) In rare cases the mutation may result in an enzyme that is more efficient, or one that can catalyse a slightly different chemical reaction ...

Microevolution

... few generations, also known as change at or below the species level. These changes may be due to several processes: mutation , gene flow , genetic drift , as well as natural selection . Population genetics is the branch of biology that provides the mathematical structure for the study of the ...

Modern evolutionary synthesis

... meiosis ). Evolution consists primarily of changes in the frequencies of alleles between one generation and another as a result of genetic drift , gene flow and natural selection . Speciation occurs gradually when populations are reproductively isolated by geographic barriers. ...

Plant

... thoughout several continents of the southern hemisphere , a fact that gave support to Alfred Wegener 's early ideas regarding Continental drift theory. References and further reading Thomas N Taylor and Edith L Taylor. The Biology and Evolution of Fossil Plants . Prentice Hall, ....

Plant

... thoughout several continents of the southern hemisphere , a fact that gave support to Alfred Wegener 's early ideas regarding Continental drift theory. References and further reading Thomas N Taylor and Edith L Taylor. The Biology and Evolution of Fossil Plants . Prentice Hall, ....

Speciation

... evolutionarily over many generations as a) they become subjected to dissimilar selective pressures and b) they independently undergo genetic drift ; particularly when one of the subpopulations is small (a scenario that leads to the " founder effect "). This kind of speciation is evident in ...
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