10/3/2023 0 Comments Genetic drift and gene flow![]() In this example, the brown coat color allele (B) is dominant over the white coat color allele (b).Ī scenario in which populations might experience a strong influence of genetic drift is during a natural disaster that kills a large portion of the population randomly and results in a large portion of the genome suddenly being wiped out is known as the bottleneck effect.Īnother situation is if some portion of the population leaves to start a new population in a new location or if a population gets divided by a physical barrier of some kind. Genetic drift in a population can lead to the elimination of an allele from that population by chance. Through random sampling, or the survival of and reproduction of a random sample of individuals within a population, allele frequencies within a population may change. Genetic drift describes the effect of a change on populations in the absence of positive or negative selection pressures. ► Natural selection strives to bring about speciation (give rise to a new species) by increasing the genetic variations in the population, whereas a constant gene flow between two populations is usually required to maintain homogeneity of the alleles in the population.ĭespite the differences in their mechanisms, these processes are constantly and simultaneously occurring in nature to drive evolution in the forward direction.Genetic drift is the change in allele frequencies of a population due to random chance events, such as natural disasters. Difference Between Gene Flow and Natural Selection Genetic drift, on the other hand, may or may not reduce the genetic variation. ► A constant genetic flow is usually required to reduce genetic variation in a population, i.e., it increases that homogeneity between the two populations in which a constant genetic flow is maintained. ► Although, the migration of alleles is observed in the founder effect, it must be noted that unlike in gene flow, where individuals migrate from one population to another, the individuals of a population migrate to a geographical region that is not inhabited by any other population. Difference Between Genetic Drift and Gene Flow Natural selection will always result in introducing more genetic variations in a population. ► Genetic drift may sometimes lead to the reduction of genetic variations, or may sometimes be responsible for introducing genetic variation in a population. ► Genetic drift is largely influenced by the population size, whereas natural selection is not. ► Natural selection will always result in the selection of allele that give an advantage to its possessor, while genetic drift may cause advantageous genes to be removed in the following generations. These new individuals make up the gene pool and are a representation of the original population in the new habitat, but in a smaller proportion. ![]() ![]() This population size will reduce further as interbreeding between the survivors may increase the chances of homozygosity of an allele that may have deleterious effect.įounder effect: When individuals of one population migrate to a new isolated geographical area (that is not inhabited by any other population) to constitute the gene pool of that area. There are two mechanisms that may give rise to genetic drift.īottleneck effect: A drastic effect (such as a natural calamity) that may cause a drastic change in the allele frequencies due to reduced population size this will lead to over representation of certain alleles in the population. Thus, an increase in the population of yellow birds is seen. As the number of yellow birds is greater than the number of green birds, there is a higher chance of the yellow birds interbreeding to give rise to more offspring as compared to that of green birds. The new generation has say, 13 yellow birds and 9 green birds. Due to some reason, yellow birds mated more successfully than the green ones. Example: In a population of ten green birds and ten yellow birds, all have equal chances of mating successfully to produce equal number of offspring.
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