Genetic Drift And Overpopulation Essay

Masatoshi et al, in their study, concluded that when small bottleneck event occurs, then as soon as populations is large enough, due to new mutations the genetic variability increases.

Genetic drift definitely did not take part whatsoever at the beginning when the population was somewhat big, but it surely started to slow down the recovery of genetic diversity once the population underwent the bottleneck event. Genetic drift only works when the population is little and there is almost no genetic variation between individuals. In other words, genetic drift should have

Founder effect: isolated individuals of a population establish a new population → limited gene pool

The founders effect can lead to a descendant population that differs greatly from its parent population over a relatively short period of time, this is referred to as genetic drift. My example goes over the Equus, which as we know was the original horse, which was as big a pony, and soft as a teddy bear. Until harsh environments, mutations through matting allowed the equus to change not only its physical appearance, but how it reacts to the change in nature. My example would be how the Equus through time started to become bigger, stronger, faster, and more deadly. This was because the Equus was very vulnerable, giving it many years to learn it weakness, and through time drifted to become stronger and more

Natural selection is the mechanism in which phenotypes and genotypes change for the population over many

Throughout the book Galapagos, by Kurt Vonnegut, the author depicts what he believes the evolution of mankind looks like and how it occurs. The four forces of evolution which can be found throughout the story are genetic drift, mutations, natural selection and gene flow. The characters of the story are on a cruise, Bahia de Darwin, heading towards Santa Rosalia in the Galapagos islands. The inhabitants on this cruise ship are the only people who remain that are capable of reproducing after an infectious outbreak which caused the rest of the population to become infertile. This is an example of genetic drift, because the outbreak of the infectious disease caused a large portion of the population to no longer

Arnold, P. (2009, December 4). Endangered Species Tasmanian Devil: Low Genetic Diversity as a Factor of the Tasmanian Devil as an Endangered Species. Retrieved March 8, 2015, from http://www.brighthub.com/science/genetics/articles/13897.aspx

Also, genetic drift can affect genetic variability in a population as well. An example of this would be the “founder effect” and the “bottleneck effect”. The founder effect is when a group of individuals become isolated from a large population, this can cause a change in allele frequencies for the already isolated individuals (Reece, 2014). For example, there are around 300 students in a classroom, if we take only 10 students to mars, they’re going to populate mars, so the entire mars colony will only depend on the alleles that those 10 people have. Another example is if a storm separates a small number of birds in a population and carries them to a separate island. The bottleneck effect is when there is a sudden decline in population size due to the environment conditions (Reece, 2014). An example of this would be if a large population of birds were mostly killed by a hurricane, leaving only a few birds

Evolution which is the ability of alleles to change within a population over time can be explained by many different forces. While some research demonstrates that variation within a population are sometimes due to survivorship (natural selection) in other scenarios, that variation happens by chance alone (genetic drift). This research focuses on the fact that natural selection and genetic drift as forces of evolution can explain the changes in an allele overtime because they are both forces of evolution. Natural selection and genetic drift were studied using beans as difference in an allele (variation of an allele in the population). It was found that in natural selection, alleles that blend well with the environment tend to survivor more. In genetic drift, some alleles are more likely to go extinct in smaller population faster than in a larger generation. These findings suggest that natural section and genetic drift as forces of evolution can explain changes in allele within a population.

The results of individual’s translocation suggested that recessive deleterious alleles were more common in the founder population, but their effects were more often masked by beneficial dominant alleles from the migrant population (Hogg et al, 2006). In some other cases heterozygosity itself is observed to have fitness advantages, while that can be highly dependent on the context of the heterozygosity. Genetic rescue also carries the risk of outbreeding depression, which can arise when populations are so divergent or locally adapted, hybrid offspring therefore have intrinsic genomic mismatches and unfit traits. Hogg et al (2006) found no evidence of outbreeding depression for any traits. In this case of population genetic rescue I think it appeared to be a success, individual with outbred pedigrees showed increases in fitness and longevity. Moreover the effective population of founder descendent that was 18.6 in 1985 has been dramatically increased, as of today the effective population of this herd is 158.26 also indicated that this population fully recovered from excessive inbreeding

Genetic drift is essentially a process in which the frequency of alleles change randomly due to sampling error between generations. It can lead to major changes in a population over a short period of time and can also lead to a fixation of alleles in that population, increasing homozygosity. Heterozygote advantage is the potential advantage that could arise out of having a single allele of a gene, even if that gene is “bad”. With a heterozygote advantage, heterozygote carriers of a certain disease will be more likely to survive than with people without the disease allele. Since it helps survival, the gene spreads more throughout the population, which is why genetic diseases are occurring more often. Hemochromatosis is most common genetic variant in people of the Western European descent because of the bubonic plague.

The bottle neck effect and the founders effect are known as the two types of genetic drift. First let us look at the bottle neck effect. Picture an empty wine bottle filled with 1000 colored marbles sitting on a kitchen table. There are three colored marbles, red, white, blue and are close to having the same amount of each inside the wine bottle. Each color represents a different genetic makeup of a species. For this example, when you turn the wine bottle upside down and 10 marbles fall out before the flow is stop. Looking at the color that fell out there are 7 red, 2 blues, and 1 white. The few marbles that fall out do not by any means represent the ratio/genetic makeup of remaining marbles inside the wine bottle. This effect happens in real life due to humans over hunting a species or by a change is the species environment.

Lastly, the differences in observed heterozygosity between the two areas may be explained by a population bottleneck. Population bottlenecks occur when a population undergoes a large reduction in size as a result of environmental events or human activities. As a result, genetic variation may decrease as certain alleles may be over presented, under presented, or completely absent, as many of the alleles that were present in the original population may be lost. Consequently, the genetic variation may continue to decline throughout subsequent generations as smaller populations, with less genetic diversity, sexually reproduce and pass on genes to future offspring. Furthermore, heterozygosity in these populations may decrease as a result of inbreeding.

Genetic drift is a deviation in the frequency of alleles in a child generation from the parental generation due to either a random event or a sampling error. A sampling error is the transmission of a nonrepresentative sample of the gene pool over space or time due to chance. Genetic drift and sampling error are similar because genetic drift is a more specific form of sampling error (Stein & Rowe, 2014).

Demography is the study of the components of population variation and change. Death rate and birth rate are two determinants of population change. Theory of Demographic Transition is comparatively recent theory that has been accepted by several scholars throughout the world. This theory embraces the observation that all countries in the world go through different stages in the growth of population. A nation's economy and level of development is directly related to that nation's birth and death rates. Population history can be divided into different stages. Some of the scholars have divided it into three and some scholars have divided it into five stages. These stages or classifications demonstrate a