Explain genetic drift and it's importance on gene pools?

Answer 1

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). The effect may cause an allele and the biological trait that it confers to become more common or more rare over successive generations. Ultimately, the drift may either remove the allele from the gene pool or remove all other alleles. Whereas natural selection is the tendency of beneficial alleles to become more common over time (and detrimental ones less common), genetic drift is the fundamental tendency of any allele to vary randomly in frequency over time due to statistical variation alone, so long as it does not comprise all or none of the distribution.

Chance affects the commonality or rarity of an allele, because no trait guarantees survival or a given number of offspring. This is because survival depends on non-genetic factors (such as the possibility of being in the wrong place at the wrong time). In other words, even when individuals face the same odds, they will differ in their success. A rare succession of chance events — rather than natural selection — can thus bring a trait to predominance, causing a population or species to evolve.

An important aspect of genetic drift is that its rate is expected to depend strongly on population size. This is a consequence of the law of large numbers. When many individuals carry a particular allele, and all face equal odds, the number of offspring they collectively produce will rarely differ from the expected value, which is the expected average per individual times the number of individuals. But with a small number of individuals, a lucky break for one or two causes a disproportionately greater deviation from the expected result. Therefore small populations drift more rapidly than large ones. This is the basis for the founder's effect, a proposed mechanism of speciation.

By definition, genetic drift has no preferred direction. A neutral allele may be expected to increase or decrease in any given generation with equal probability. Given sufficiently long time, however, the mathematics of genetic drift (cf. random walk) predict the allele will either die out or be present in 100% of the population, after which time there is no random variation in the associated gene. Thus genetic drift tends to sweep gene variants out of a population over time, such that all members of a species would eventually be homozygous for this gene. In this regard, genetic drift opposes genetic mutation which introduces novel variants into the population according to its own random processes.

hope it helps.

Answer 2

The flu virus of 1918 went thru both genetic drift and genetic shift. The drift occurred with the chaotic replication of the virus, which is normal in RNA based viruses. Very few of new viruses have the identical nine genes of the orginal. This drift was not important in the first flu wave, lots of sick people, but most recovered, some deaths. Then a shift occurred when two virus reproduce in a single host cell, now eighteen genes recompose to form some of the new viruses. This virus was virulent and lethal and in a 24 week period from September 1918 to March 1919 almost 450,000 Americans died of the flu, most of the victims were in the 20 to 30 year old age group. 50,000 young army soldiers were killed in the epidemic in 1918 and 1919 before the epidemic died out. The devastation of this epidemic set up the world wide flu virus watch network which almost instantly studies and acts when a flu threat is identified. Good for us, but hard on birds from which the 1918 virus orginated.

Answer 3

Very basically, genetic drift is the gradual change of the genes in a population that is isolated from other populations. As little changes accumulate, the gene pool becomes more and more different from that of other populations as time goes by.

My students always confuse this with gene flow - which is what happens when individuals with different genes move into a population or when individuals move out of a population taking their genes with them. Gene flow has a much bigger impact in small populations than in big populations.

Answer 4

Sorry t. mcgee, you have at a loss for words genetic drift with gene bypass. BioLiz, mutation truly has no longer something to do with this. Genetic drift is the tendency for one gene version to alter into "fastened" in a inhabitants. this suggests that via completely random methods (alongside with mutation, drift is the only random technique in evolution), purely one gene version is composed of exist in a inhabitants, so its frequency is one hundred% (the different variations are at 0% frequency). So in this feeling drift subtracts from the gene pool because of the fact different variations are eradicated over the years. the end result would be a inhabitants with much less genetic version, and consequently an increasing style of project to extinction because of environmental replace (like illnesses). luckily, genetic drift has a great result purely in small populations the place inbreeding is intense and genetic recombination nonetheless produces little version. it isn't the case in great populations.