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Topic: Genetic drift


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In the News (Thu 18 Apr 19)

  
  Genetic drift - Wikipedia, the free encyclopedia
Genetic drift is the term used in population genetics to refer to the statistical drift over time of allele frequencies in a finite population due to random sampling effects in the formation of successive generations.
In a narrower sense, genetic drift refers to the expected population dynamics of neutral alleles (those defined as having no positive or negative impact on fitness), which are predicted to eventually become fixed at zero or 100% frequency in the absence of other mechanisms affecting allele distributions.
Genetic drift may be modeled as a stochastic process that arises from the role of random sampling in the production of offspring.
en.wikipedia.org /wiki/Genetic_drift   (1138 words)

  
 ScienceDaily: Genetic drift   (Site not responding. Last check: 2007-11-07)
Genetic drift is the term used in population genetics to refer to the statistical drift over time of gene frequencies in a population due to random sampling effects in the formation of successive generations.
In a narrower sense, genetic drift refers to the expected population dynamics of neutral alleles (those defined as having no positive or negative impact on reproductive fitness), which are predicted to eventually become fixed at zero or 100% frequency in the absence of other mechanisms affecting allele distributions.
Genetic drift -- Genetic drift is the term used in population genetics to refer to the statistical drift over time of gene frequencies in a population due to random sampling effects in the formation of successive...
www.sciencedaily.com /encyclopedia/genetic_drift   (2448 words)

  
 Population Genetics of Plant Pathogens | APSnet Education Center | Genetic Drift   (Site not responding. Last check: 2007-11-07)
Genetic drift is a process in which allele frequencies within a population change by chance alone as a result of sampling error from generation to generation.
Under a scenario of pure genetic drift, the probability of fixation of an allele in a population is its initial frequency in the population.
An extreme example of genetic drift due to a bottleneck is the population of the Phytophthora infestans pathogen that causes late blight of potatoes.
www.apsnet.org /education/AdvancedPlantPath/Topics/PopGenetics/Pages/geneticdrift.htm   (1683 words)

  
 Random Genetic Drift
One aspect of genetic drift is the random nature of transmitting alleles from one generation to the next given that only a fraction of all possible zygotes become mature adults.
Drift is also not confined to diploid genetics; it can explain why we all have mitochondria that are descended from those of a single women who lived hundreds of thousands of years ago.
The genetic make-up of the icelandic cattle is now different from that of their cousins in Norway but the differences agree well with those predicted by genetic drift.
www.talkorigins.org /faqs/genetic-drift.html   (1812 words)

  
 Genetic drift Info - Encyclopedia WikiWhat.com   (Site not responding. Last check: 2007-11-07)
Small populations' greater susceptibility to drift is a manifestation of the law of large numbers, which is especially easy to see in tossing coins.
Teasing apart the relative influence that drift and selection have had over the course of evolution, both with respect to individual species as well as with regard to the history of life in general, is a primary aim of evolutionary biology.
From the statistical perspective of population genetics, drift is a "sampling effect".
www.wikiwhat.com /encyclopedia/g/ge/genetic_drift.html   (1380 words)

  
 A reduction of "Species"- genetic drift and population structure
Under this scenario the pattern of genetic drift, as well as the pattern of genetic variation, among organisms may not be structured but may follow a continuous pattern over some environmental landscape.
Genetic drift may occur over a short time scale among the cells in a single colony on a petri dish, and over a longer time scale among the population of cells within the intestine of a single mammal.
Rapid genetic drift may result either from ecological circumstances that sharply curtail reproduction or from the appearance of a strongly favored mutation.
lifesci.rutgers.edu /~heylab/sconcept/population.html   (1150 words)

  
 Genetic drift - CreationWiki   (Site not responding. Last check: 2007-11-07)
Genetic drift refers to the net decrease in genetic variability and heterozygosity over time.
Genetic drift is the process by which populations are stripped of their heterozygosity over time.
In the long-run, genetic drift and natural selection cause populations to be very specialized and adapted to their particular environment, but exhibiting so little variation as to be unable to adapt to other environments.
www.nwcreation.net /wiki/index.php?title=Genetic_drift   (1242 words)

  
 Zoology 304, Evolution
In genetic drift, as in a random walk, the random change at each generation begins with the frequencies of the previous generation.
Genetic drift refers to the total set of processes wherein random sampling of allelic variation (whether by the "Mendelian lottery" or by chance survival unrelated to fitness or by chance matings unrelated to fitness) leads to changes in allele frequency from generation to generation.
Genetic drift has some considerable significance for evolutionary biology, especially for understanding and interpreting variation which may be observed at the molecular level.
www.science.siu.edu /zoology/King/304/wk3.htm   (3380 words)

  
 Evolution - A-Z - Genetic drift
Genetic drift has important consequences for the random substitution of genes and the Hardy-Weinberg equilibrium.
The rate of change of gene frequency by random drift depends on the size of the population.
On average, there would be 50% heads in both cases, but the chance of flipping 12 heads and eight tails in the small population is higher than the chance of flipping 2400 heads and 1600 tails in the large.
www.blackwellpublishing.com /ridley/a-z/Genetic_drift.asp   (256 words)

  
 Genetic Drift
Here are the figures I used in lecture on Friday, March 27, to talk about the statistical predictions for the outcomes of genetic drift.
This process of population divergence due to drift is shown in another way in the next figure.
After 10 generations, there is a loss of genetic variation of about 40% with a population size of 10, 65% with a population size of 5, and 95% with a population size of 2.
www.wooster.edu /biology/mloveless/Drift.html   (849 words)

  
 Lab Manual Exercise #6
Genetic drift is a plausible explanation for how racial differences may have first emerged in small, isolated populations when the earth was sparsely inhabited by tribes of people.
The founding colony does not have the genetic variability of the main population, and the frequency of certain traits may increase greatly by genetic drift compared with the much larger ancestral population.
Genetic disorders involving an excess accumulation of lipids or sugars inside cells are called "storage diseases." The cells become bloated and vacuolated (with enlarged vacuoles).
waynesword.palomar.edu /lmexer6.htm   (3958 words)

  
 Genetic variation - Wikipedia, the free encyclopedia
Genetic variation refers to the variation in the genetic material of a population or species, and includes the nuclear, mitochodrial, ribosomal genomes as well as the genomes of other organelles.
New genetic variation can be caused by mutations, recombinations, migration, genetic drift and alterations in the karyotype (the number, shape, size and internal arrangement of the chromosomes).
When two or more alleles of a gene are present in a gene pool, the population is said to be polymorphic.
en.wikipedia.org /wiki/Genetic_variation   (384 words)

  
 evolgen archive: William Provine and the Biological Meaning of Genetic Drift
Genetic drift refers to the change in allele frequencies due to random sampling in finite populations.
Neutral evolution and genetic drift must be viewed as different processes rather than the byproduct of a process (as the former is thought to relate to the later).
Provine's point was not that genetic drift is impossible (it clearly is not under the correct parameters), but that is not realistic because of genetic linkage.
evolgen.blogspot.com /2005/09/william-provine-and-biological-meaning.html   (2192 words)

  
 [No title]   (Site not responding. Last check: 2007-11-07)
Although genetic drift is not due to the influence of a particular trait on reproduction or survival, it can change the frequency of alleles from one generation to the next, and hence, can cause evolutionary change.
Genetic drift can, for example, cause alleles that are harmful to reach a frequency of 100% and it can cause beneficial alleles to reach a frequency of 100%.
As this example suggests, genetic drift is “blind” to the adaptive value of alleles and hence it can lead to the fixation of harmful or beneficial alleles.
www.rose-hulman.edu /class/AppBio/OldFiles/ab130/Handouts/Lab2.Drift.Sel.doc   (2314 words)

  
 genetic drift
genetic drift Change in allele frequency from one generation to another within a population, due to the sampling of finite numbers of genes that is inevitable in all finite-sized populations.
The smaller the population, the greater is the genetic drift, with the result that some alleles are lost, and genetic diversity is reduced.
First, small random genetic changes are always accumulating in a virus, a process known as genetic drift.
www.mongabay.com /igapo/biotech/genetic_drift.html   (658 words)

  
 EvoTutor: H-W Equilibrium
For this simulation the size of the population undergoing genetic drift is 400.
For obvious computational reasons, the size of the population "without drift" is 4000, instead of infinity.
Genetic drift causes the population to deviate noticeable from this line.
www.evotutor.org /EvoGen/EG1A.html   (377 words)

  
 Evolution: Library: Genetic Drift and the Founder Effect
The syndrome is commonly found among the Old Order Amish of Pennsylvania, a population that experiences the "founder effect." Genetically inherited diseases like Ellis-van Creveld are more concentrated among the Amish because they marry within their own community, which prevents new genetic variation from entering the population.
The founder effect is an extreme example of "genetic drift." Genes occurring at a certain frequency in the larger population will occur at a different frequency -- more or less often -- in a smaller subset of that population.
As in the example of human diseases, genetically determined traits that would ordinarily be uncommon in the overall gene pool might crop up with distressing frequency in a small subset of that pool.
www.pbs.org /wgbh/evolution/library/06/3/l_063_03.html   (460 words)

  
 Random Genetic Drift
The amount of drift is inversely proportional to population size.
With drift, there is some probability that the allele frequency in the next generation could be any value.
Genetic variance among individuals is proportional to 2pq.
www.zoology.ubc.ca /~whitlock/bio434/LectureNotes/04.Drift/Drift.html   (699 words)

  
 Definition For Genetic Drift Articles   (Site not responding. Last check: 2007-11-07)
Dictionary definition of genetic drift browse dictionary by alphabet 0 1 2 3 4 5 6 7 8 9 a b c d e f g h I j k l m n o p q r s t u v w x y z top words ge gean geanticlinal gear gearing gecarcinian.
Genetic drift is another mechanism by which evolutionary changes may occur.
Central to the definition of genetic drift is the assumption that genes.
www.genetics-research.info /definition-for-genetic-drift.html   (1029 words)

  
 Population Size and Genetic Drift
Genetic drift: the effect of population size alone on allele and genotype frequencies
Because of genetic drift, the variance between demes (small subpopulations) increases over time (i.e., demes will diverge, esp. if they become isolated).
The trend toward homozygosity from inbreeding and drift is offset ("balanced") by mutation and gene flow
www.nyu.edu /projects/fitch/courses/evolution/html/genetic_drift.html   (1229 words)

  
 Gene Expression: Can't have genetic drift without the other....
It isn't like genetic drift can't result in variation...but the researcher seemed to be pointing to founder effect which would homogenize alternative populations and "fix" them into alternative states.
It seems clear that as N approaches infinite there won't be a change, random genetic drift will not sift out the variation from the population because the sampling process is too weak of a force.
Long term equilibrium gene frequencies under drift & migration (between populations) is 1/(4Nm + 1), where N is effective population again, and m is the proportion of migrants within a given generation.
scienceblogs.com /gnxp/2006/04/cant_have_genetic_drift_withou.php   (1048 words)

  
 Genetic Drift
Genetic drift From Biocrawler Genetic drift is a mechanism of evolution that acts in concert with natural selection to change the characteristics of species over time.
Genetic drift Main Page Genetic drift is a mechanism of evolution that acts in concert with natural selection to change species characteristics over time.
genetic drift Genetic drift is the change in a population's gene pool that is due to chance.
www.dnalabtesting.com /genetic/geneticdrift   (1284 words)

  
 Genetic drift - The Gardens Cure
Genetic drift is a myth, there is no valid scientific reason to suggest that the genes 'decay' within the plant or drift.
Genetic drift is something that happens on populations, where certain genetic make-ups will decay based on time.
As I said before, GENETIC DRIFT IS A POPULATION PHENOMENON, which means that it relates to the overall change in the number of alleles in a population.
www.gardenscure.com /420/showthread.php?s=&threadid=7380&highlight=Shantibaba   (1347 words)

  
 Definition For Genetic Drift
This definition is from the Glossary at the conditioners, and solvents that drift to the upper stratosphere and An autosomal recessive genetic disorder that causes the >>
Genomics glossary genetic architecture: Related term: Genomics glossary complex traits genetic drift: Random fluctuations in gene frequencies, particularly in small populations.
population by random genetic drift that the delicate equipoise in the environment and in the genetic outfit of the organism (Ford explicitly excluded from the definition of genetic polymorphism by >>
www.dnalabtesting.com /dnatest/definitionforgeneticdrift   (1443 words)

  
 INBREEDING AND GENETIC DRIFT
Genetic variation was studied by means of a DNA fingerprint technique called "Amplified Fragment Length Polymorphisms" - AFLP for short.
that produces approximately the same rate of genetic drift in their simple models as does the actual population with all its complexity.
Drift may or, may not be important in evolution, but it always happens, because populations are always finite.
www.ucl.ac.uk /~ucbhdjm/courses/b242/InbrDrift/InbrDrift.html   (2317 words)

  
 Ernst Mayr's theory illustrated in genetic epidemiology studies
Mayr believed that genes interacted with one another, and that this genetic interaction in turn led to an interaction of natural selection with genetic drift that could cause genetic revolution — new directions of evolutionary change.
Because the population is very small, there is a lot of genetic randomness, and there is only a subset of the genetic variation of the ancestral population, and the frequencies of different kinds of genes can be changed dramatically.
Templeton said that there are still a lot of biologists who don't like the idea of genetic drift, but he thinks that they miss two very important concepts of Mayr's argument.
www.eurekalert.org /pub_releases/2006-02/wuis-emt013106.php   (1129 words)

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