Compare Directional Selection And Disruptive Selection

Resistant bacteria form from the overuse of antibiotics. What happens is, an antibacterial drug is

Most of the ill-causing bacteria will be killed but the ones that don’t die, carry a gene or genes that allows them to withstand the antibiotic. These bacteria are better adapted to deal with the antibiotic. This adaptation will become stronger as it is passed. When these bacteria reproduce, they will pass the genes on to the next generation and the next generation bacteria better adapted against the antibiotic. The more they reproduce, the more antibiotic resistant bacteria will be in the individual eventually becoming totally resistant. This is an example of directional selection in the natural selection process. The bacteria with the resistant genes would become the favored extreme phenotype.

Many pathogenic bacteria species are becoming resistant to antibiotic. Explain how such adaptations can develop through the process of natural selection.

Directional selection and disruptive selection have quite a bit in common; however, they also have some contraries. Their biggest likeness is that they are both subcategories of natural selection. Natural selection is the process that results in adaptation of a population to the biotic and abiotic atmospheres. Directional selection takes place when an exaggerated phenotype is favored and the distribution curve alters in that direction. Such a shift can happen when a population is adjusting to a changing environment. Disruptive selection occurs when two or more extreme phenotypes are favored over any other ordinary phenotype. These two selections differ in that directional requires only one extreme phenotype whereas disruptive requires at least two. A prime example of a directional selection, is resistance to antibiotic treatment as well as insecticides. The extensive application of antibiotics and pesticides eventually develops populations of bacteria and insects that have grown resistant to the chemicals. When an antibiotic is employed, some bacteria may survive because they are genetically defiant to the treatment. These particular bacteria are likely to provide such genes for the next generation. As an outcome, the number of bacterial defiance continues to increase. Disruptive selection favors polymorphism, which is the happenings of different forms in a population of the exact same species. With thatstatement made, a classic example of disruptive selection would be that

Predatory selection demonstrated heavily on how the predators prefered brighter males and how females then resorted to whatever was left. From my data of mostly drab and mostly bright guppies with the simulation having 30 rivulus, 30 acara, and 30 cichlids, I could see a clear trend. For the mostly drab guppies, in a mere 7 generations or 141 weeks, showed that the predators had wiped out the brighter guppies having a split demographic of 0% of the brightest and bright guppies, 30% for drab guppies and 70% for the drabbest of guppies. In the mostly bright guppy test, it was more even but showed an obvious lean towards the drabber guppies having 20% and 17% for brightest and bright guppies, and 17% and 46% for the drab and drabbest guppies respectively. With all this data, the trend leaned towards having the bright guppies

Natural selection involves the adaptation of a species to better survive in their designated environment. When organisms reproduce, they pass down their DNA to their offspring. For example, a child that is tall is the result of their parent being tall as well. Parents pass down traits to their children. When it comes to survival, some organisms are better at it than others based on the traits that they have acquired. Some organisms can camouflage from predators while members of the same species do not obtain that same trait. With that in mind, the ones that can camouflage will most likely survive in certain environments and they will then pass on that trait when they reproduce. Since these traits are advantageous, they are passed on to more and more offspring through time and it will eventually overcome any original traits that species first started out with. It’s kind of like the current state of sexual misconduct in Hollywood. We have our directors, actors, agents, and so forth. However, as time goes on, some do not survive in the business based on their inherently evil traits and they get weeded out just like some species in the wild. As generations pass, these organisms have then adapted to fit the environment and better survive based on their inherited traits.

Directional selection is one of the types of natural selection. In directional selection, one extreme of a trait in a population experiences pressure against it. This causes a shift in the population’s genetic variance to a trait with less pressure against it. This then results in the population gradually shifting from the pressured extreme trait to the unpressured extreme trait on the other side of the spectrum. Giraffe necks are a familiar example. There was environmental pressure against the giraffes with short necks, because the individuals couldn’t reach as far to feed. Therefore, the variance of neck length shifted towards long necks from short necks. Another example is the evolution of the peppered moth in 18th to 19th century England.

There are many different types of breeding, but two main types are selective and natural breeding. Both of these types of breddings are involved in something else and are nothing like each other. Each breeding causes something else, and is involved with another part of their environment.

Antibiotic resistance evolves in bacteria. Charles Darwin created the theory of evolution which focused on natural selection being the key factor of how things change. Natural selection is when organisms that are better suited to the environment are able to reproduce successfully. Evolution is descent with modification. Bacteria can become resistant to antibiotics by a mutation. The bacteria that did not die from the antibiotic inherited the gene from an ancestor that made it resistant. Since the other bacteria is dying faster than the resistant bacteria, the resistant bacteria are able to multiply

Both directional and disruptive selection is a type of natural selection. Natural selection is the differential survival and/or reproduction of organisms as a function of their physical attributes. (phenotype) This results in evolution over many generations. Each mode of selection alters the mean or variance of a phenotypic trait in a population or species. These distributions can be represented in bell curves. Both selection processes can be influenced by human interaction.

· Be able to describe how antibiotic resistant genes are able to transfer, and identify the transformed cells that are antibiotic resistant

aureus would have to adapt to the toxin in its' environment or become extinct. By 1950, the bacteria gained immunity to the toxins, penicillin would no longer be an effective source of killing the bacteria; and a new antibiotic would soon be used to fight the penicillin resistant bacteria. Methicillin became the preferred drug to destroy S. aureus. Consequently, the overuse and misuse of antibiotics has allowed S. aureus to undergo natural selection again. The bacteria has mutated and adapted; it is resistant to methicillin. Thus, S. aureus ensures its survival and portrays the relevance of natural selection in the 21st century (http://www.niaid.nih.gov/topics/antimicrobialResistance/Examples/mrsa/Pages/history.aspx).

The evolutionary advantage theory proposes that symmetric individuals are attractive because they are particularly healthy, and the perceptual bias theory proposes that symmetric individuals are attractive because the human visual system can process symmetric stimuli of any kind more easily than it can process asymmetric

In doing research for an example of natural selection, I came across antibiotic resistant bacteria. This has become one of the biggest threats to the healthcare community and Center for Disease Control. Through the use of antibiotics in treatments that are not necessarily bacterial infections, as well as the over use and misuse of antibiotics, bacteria have evolved in ways making the antibiotics used against them useless. If a bacteria manages to survive through a dose of an antibiotic, they are capable of mutating and can transfer their DNA to other bacteria. The new bacteria multiply quickly and spread to other parts of your body or outside of your body to a new host. Once the bacteria have mutated and its DNA has been transferred to

Antibiotics was developed to combat bacteria by zero in on the bacteria’s structure. As time goes by bacteria can defeat antibiotics in their natural selection. Natural selection plays an important role in the progression of antibiotic resistance. Most of the bacteria dies when it is exposed to antibiotics they are sensitive to. Therefore, it creates more space and availability of nutrients for the surviving antibiotic-resistant bacteria. Subsequently,