Genetic drift can completely eliminate an allele from a population. Genetic drift is one of the mechanisms of evolution, along with descent with modification, mutation, migration, and natural selection (Mechanisms: The Processes of Evolution). Benefits and drawbacks can come from genetic drift.
When a population's genetic makeup is changed randomly, it is called genetic drift. In natural selection, environment is the selection agent but in genetic drift, chance is the selection agent (Nowicki 305). Since genetic drift is controlled by chance, smaller populations are more prone to being affected by genetic drift. If someone flips a coin six times, the results will not always be split between heads and tails at fifty percent. Although if someone flips a coin one thousand times, the percentage of heads and tails will be closer to fifty percent (Small Population Side Effects). Genetic drift can start from things called the bottleneck effect or the founder effect (Nowicki 336).
The bottleneck effect can make a population small enough for genetic drift to affect it. Nowicki writes, "The bottleneck effect is genetic drift that occurs after an event greatly reduces the size of a population." (Nowicki 336). These events could include natural disasters like earthquakes, or it could be overhunting. In the 1890's northern elephant seals were massively hunted, much less than the southern elephant seals. This hunting brought the northern elephant seal count down to approximately 20 seals. Even now, you can see the effects from that occurrence of the bottleneck effect. The southern elephant seals, who were not hunted as much, are extremely more genetically diverse than the northern elephant seals. After the event, some of the alleles become fixe...
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Why is genetic variation necessary in a population in order for natural selection to occur?
Biological evolution is a change in the characteristics of living organisms over generations (Scott, 2017). A basic mechanism of evolution, the genetic drift, and mutation is natural selection. According to Darwin's theory of evolution, natural selection is a process in nature in which only the organisms best adapted to their environmental surroundings have a higher chance of surviving and transmitting their genetic characters in increasing numbers to succeeding generations while those less adapted tend to be eliminated. There has been many experimental research projects that relate to the topic of natural selection and evolution.
Evolution is the process by which organisms develop unique derived traits. Evolved traits that decrease an organism’s survival rate are selected against in a population. Traits that increase an organism’s survival rate, on the other hand, are often selected for, meaning that those traits will appear more frequently in the genetic codes of members in a population. This process of selection can take several forms, one of them called sexual selection. Sexual selection occurs when one member of a particular species selects a mate with more favorable traits than other members of their species. An example of sexual selection would be the evolution of “hairlessness” in modern humans. Modern humans do not have a single coat of undiversified hair, unlike
When it comes to genetic diversity and migration, migration is known as the movement of genetic diversity within a species. Migration of genes not only happens in animals but also in plants through pollen dispersal, vegetative propagules like rhizomes and suckers among others. Migration or in other term gene flow, is said to take place both with the proceeding front of a population when it is colonizing new areas. This happens when genes of two or more populations mix through pollen and seed dispersal. In this case, migration rate is mainly related to the frequency of reproduction and the distance over which seeds and pollen usually disperse.
Natural selection is associated with the phrase “survival of the fittest.” This basically means that the fittest individuals can not only survive, but are also able to leave the most offspring. The selection of phenotypes affects the genotypes. For example, if tall pea plants are favored in the environment, then the tall pea plants would leave more offspring behind, meaning that the offspring will carry tall alleles. Phenotypes that are successful have the best adaptations (characteristics that help an individual to survive and reproduce) to their environment. These adaptation arise from the interactions with living and nonliving aspects of the environment. Some nonliving aspects of the environment are climate, water availability, and concentration of mineral sin the
In the Genetic Drift Experiment, I was unable to learn much. This is mostly because in the second sub-experiment, I was only able to record one of ten trials. The directions stated to not record any extinctions that happened after 500 generations. Only one of the trials fit the requirements. Therefore, I could not thoroughly compare the two sets of data. However, I can draw from one of the readings to support my hypothesis. Dawkins states that all living things result from genes creating “survival machines” in order to ensure their survival (Dawkins, blah blah). If these survival machines have a bigger population, then they can continue to pass on their survival genes even if a terrible random mechanism takes out a large chunk of their population. This is because even though it kills off a large portion; there is still a large population left to reproduce. For the second experiment, I had three hypotheses. The first was that a population with a higher fertility rate will be less likely to become extinct. The data on this did not back up my hypothesis. Instead, as one can see in the data above and attached in the packet, any group, large or small, has the advantage of not going extinct as long as they have a higher fertility rate than another competing group. After giving this some thought, I have found that this makes a lot of sense and can be backed up by the reading regarding Darwin’s finches. In the newer study of his finches, they have found that those who were able to survive drastic changes and continued to reproduce were the ones who evolved to keep their species alive for longer. The next sub-experiment had required another hypothesis: if the size of the difference in fertility is slightly higher, then that will become more apparent overtime. This hypothesis can be proven true my referring to the tables that I have listed above. In the tables, it is
Acquired Immune Deficiency Syndrome (AIDS) was first recognized as a new disease in 1981 when increasing numbers of young homosexual men succumbed to unusual opportunistic infections and rare malignancies (Gallant49).During this time, many people were contacting this disease because it was not discovered yet and people did not have knowledge about it.Scientists believe HIV came from a particular kind of chimpanzee in Western Africa. Humans contracted this disease when they hunted and ate infected animals. A first clue came in 1986 when a morphologically similar but antigenically distinct virus was found to cause AIDS in patients in western Africa (Goosby24). During this time, scientists had more evidence to support their claim about this disease. Once discovered this disease was identified as a cause of what has since become one of the most devastating infectious diseases to have emerged in recent history (Goosby101). This disease was deadly because it was similar to the Black Death, it was killing majority of the population. Since its first identification almost three decades ago, the pandemic form of HIV-1 has infected at least 60 million people and caused more than 25 million deaths ...
Evolution is a on going process and the evolution is made up of many different processes. It allows species to become what they are, how they act, and what they will become. It also allows species to be able to survive. It produces new and different species through ancestral populations of organisms and moves them to new population. Both natural selection and genetic drift decrease genetic variation. If they were the only mechanisms of evolution, populations would eventually become homogeneous and further evolution would be impossible. There are, however, mechanisms that replace variation depleted by selection and drift (Colby).
HIV is a lentivirus, and like all viruses of this kind, it attacks the immune system. Lentiviruses are in turn part of a bigger group of viruses known as retroviruses. The name 'lentivirus' literally means 'slow virus' because they take such a long time to create any unfavorable effects in the body. They have been found in plenty of different animals, including cats, sheep, horses and cattle. However, the most appealing lentivirus in terms of the investigation into the origins of HIV is the Simian Immunodeficiency Virus (SIV) that affects monkeys, which is believed to be at least 32,000 years old(7).
...generations. If it is a beneficial mutation, then it will likely not only pass on through reproduction, but those offspring will have better odds of reproducing in order to “spread” that trait onto future offspring. This is the process of natural selection. If there are enough changes or the change is drastic enough, a new species can evolve. So, evolution comes about as a result of changes to DNA and some of those changes to DNA can come from external factors such as environment, climate, and culture.
According to Darwin and his theory on evolution, organisms are presented with nature’s challenge of environmental change. Those that possess the characteristics of adapting to such challenges are successful in leaving their genes behind and ensuring that their lineage will continue. It is natural selection, where nature can perform tiny to mass sporadic experiments on its organisms, and the results can be interesting from extinction to significant changes within a species.
Many scientists in the past, such as Aristotle and Plato, believed that there were no changes in populations; however, other scientists, such as Darwin and Wallace, arose and argued that species inherit heritable traits from common ancestors and environmental forces drives out certain heritable traits that makes the species better suited to survive or be more “fit” for that environment. Therefore, species do change over a period of time and they were able to support their theory by showing that evolution does occur. There were four basic mechanisms of evolution in their theory: mutation, migration, genetic drift, and natural selection. Natural selection is the gradual process by which heritable traits that makes it more likely for an organism to survive and successfully reproduce increases, whereas there is a decline in those who do have those beneficial heritable traits (Natural Selection). For example, there is a decrease in rain which causes a drought in the finches’ environment. The seeds in the finches’ environment would not be soft enough for the smaller and weaker beak finches to break; therefore, they cannot compete with the larger and stronger beak finches for food. The larger and stronger beak finches has a heritable trait that helps them survive and reproduce better than others for that particular environment which makes them categorized under natural selection (Freeman, 2002).
The Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome, commonly known as HIV/AIDS is a disease, with which the human immune system, unlike in other disease, cannot cope. AIDS, which is caused by the HIV virus, causes severe disorder of the immune system and slowly progresses through stages which disable the body’s capability to protect and instead makes it vulnerable for other infections. The first blood sample to contain HIV was drawn in 1959 in Zaire, Africa while molecular genetics have suggested that the epidemic first began in the 1930s (Smallman & Brown, 2011). Currently, according to the Joint UN Program on HIV/AIDS, 35.3 million people worldwide are living with HIV. In 2012, an estimated 2.3 million people became newly infected with the virus and 1.6 million people lost their lives to AIDS (Fact Sheet, UNAIDS). It is due to the globalized international society that a disease which existed in one part of the world has managed to infect so many around the world. Globalization is narrowly defined by Joseph Stiglitz as "the removal of barriers to free trade and the closer integration of national economies" (Stiglitz, 2003). Globalization has its effects in different aspects such as economy, politics, culture, across different parts of the world. Like other aspects, globalization affects the health sector as well. In a society, one finds different things that connect us globally. As Barnett and Whiteside point out (2000), “health and wellbeing are international concerns and global goods, and inherent in the epidemic are lessons to be learned regarding collective responsibility for universal human health” (Barnett & Whiteside, 2000). Therefore, through all these global connections in the international society, t...
There are many inequities in this global world; should there be such gross inequities in the health of people around the world? We hear words like health gap, health care inequality and sustainability. What can be done to eliminate the health gap, health care inequities and maintain sustainability? The World Health Organization (WHO) and other organizations, private and public are working towards eliminating these disparities. Healthy People 2020 are one such goal that has achieved considerable progress in attaining sustainability in the pursuit of global health goals (Gostin et al., 2013). The health gap can be minimized through health strategies. Among them are essentials for all in this global world; clean air, water, healthy food and adequate housing with hygienic living conditions. Primary, secondary, tertiary prevention and care services should be available to all who seek health care services.
Another mechanism is a hereditable type of evolution is mutations. Mutations are alterations to a gene. Mutation can be harmful, beneficial or neutral. Mutations are the origin of the source of genetic diversity (9).Mutation that are harmful, hinders the chances of the organism chances of survival and are likely to die along with the mutations. Beneficial mutations increase the chances of the individual to survive in its environment, and they will be more likely to reproduce and pass on the gene to future generations (9).