Example Of Natural Selection

When non-resistant bacteria are exposed to an antibiotic, most of them die. But due to the increase of mutations some of the bacteria are becoming resistance to the antibiotic. The bacteria are all subject to natural selection. Natural selection is as simple as saying that the bacteria that have not developed a mutation or resistance that helps them to survive die. The ones that do, survive and pass on the mutation to the next generation. This means that we are constantly having to adapt our antibiotics because so much of the mutation is getting passed along. The flu vaccination is a good example of how mutations are carried over and how the vaccine had to be changed every year to fight the ever changing virus. Some strains

Evolutionary biology has always interested me, specifically the mechanisms of natural selection and how species adapt to their environment. It started with my love for animals and nature when I was little. I spent my summers working with horses at a local corral, where I would ride around the surrounding wilderness areas. My favorite part about riding in the mountains was watching the change in plant and animal species as the elevation changed. It never ceased to amaze me how the alpine tree line was always so sudden. Humongous pine trees would give way to the short, shrubby plants of the alpine tundra so uniformly and noticeably. I have always wondered about the environmental conditions that cause species to distribute themselves in

Another crucial element to consider is the emergence of bacterial strains resistant to antibiotics,given the widespread use of these drugs as a prophylactic or a therapeutic regimen.

Darwin came up with a good idea but the animals he compared were a bit too farfetched. Using a whale as an example of evolution by natural selection is an example which is still used today.

Darwin: Well in that case I suppose that it could affect natural selection in that if a food source or necessity is changed that it could encourage recessive phenotypes but overall the ones best suited for the environment would be able to survive.

The root of this problem lies in what Charles Darwin called the “survival of the fittest” in which organisms eventually adapt and evolve in response to their environment and its impending threats in order to survive. Bacteria is now doing this in response to antibiotics, which are purposed to kill bacteria so as to eliminate infections and diseases. However, now more and more bacteria are evolving to form antibiotic-resistant strains that there are no or very expensive antibiotics or treatments for yet, even if they were once easily treated diseases. Often this is a result of overuse or improper use of antibiotics by both medical professionals and patients. Overuse, such as attempting to use antibiotics for infections that do not warrant them, such as the common cold, allows existing bacteria to devise mechanisms such as “neutralizing” antibiotics, removing antibiotics, adapting their structure so as to become impenetrable to the antibiotics, or improving upon their genetics. Improper use of bacteria, such as beginning an antibiotic, but failing to use it to completion, also allows bacteria to do the

I certainly remember sitting in high school biology class and reaching the point in the year when microbial and bacterial genetics and replication is covered. That topic was always capped with the unfortunate fact that a unnerving amount of diseases, whether they be bacterial, fungal, parasitic, and on the rare occasion, viral, are becoming resistant to the commonplace pharmaceuticals used to remedy them. Disease such as tuberculosis, MRSA, gonorrhea, and CDIFF, that have proven to be fatal, have a new trick up their molecular sleeve to further bring harm to patients everywhere. They have grown resistant to their typical medicines – usually antibiotics – making the disease harder to get treat, get rid of, and prevent from spreading.

Resistance is easily spread, either ‘horizontally’, through gene exchange within bacteria, or ‘vertically’, through sequential mutation and formation of antibiotic resistance through new generations. (State Government of Victoria 2015) A massive 80-90% of antibiotics ingested are excreted as waste because they are not broken down inside the body. They then enter the environment, allowing gene transfer to occur and facilitating resistance in more bacteria. Therefore, as resistance is spread so easily, the risks become even higher. Additionally, if antibiotics continue to be used so abundantly, the majority will be made resistant due to the widespread use. Moreover, as the current degree of antibiotic use continues, then society’s ability to treat common infectious diseases sharply increase. Those infected with superbugs are unable to respond to standard medicine, thus are ill for a longer period of time, accumulate higher health care costs, and have a greater risk of mortality. According to the World Health Organisation, people with MRSA (methicillin-resistant Staphylococcus aureus), a common infection in hospitals, are 64% more likely to die in comparison with people with the non-resistant form of Staphylococcus aureus. Additionally, as individuals are

Today, the use of antibiotics is very common. The gene that causes antibiotic resistance typically arises naturally or from a mutation. When bacteria are exposed to antibiotics, the bacteria with antibiotic resistance genes within the plasmid survive; this is called selective advantage. This process of the survival of bacteria that are resistant to antibiotics is a method of natural selection, causing more antibiotic resistant bacteria to be reproduced. They are rapidly reproduced by binary fission, conjugation, transformation,

Bacteria that develop resistance to antibiotics are mutations that have evolved through the adaptation of their environment (Bethel). Scientific research has shown that the with evolution of bacteria that infectious diseases, such as tuberculosis, are re-emerging (Hassan). The bacteria Mycobacterium tuberculosis did not evolve alone because we have evolved ourselves. Scientists and many humans, after the discovery of penicillin in 1928 by Alexander Fleming, thought that the era of infectious diseases was over, but that era lasted only about 50 years.

Antibiotics have been an important instrument in public health since 1928, saving the lives of people around the world. According to the Centers for Disease Control and Prevention (2015), about half of antibiotics used in human and animals are unnecessarily and inappropriately prescribed, leading to the emergence of drug resistance in bacteria (CDC, 2015). The CDC estimates that drug-resistant bacteria cause two million illnesses and approximately 23,000 deaths each year in the United States alone (2015).

The second scenario is an example of evolution because evolution has to have a change in the gene frequency. The first scenario doesn’t show a change in gene frequency. The first picture in the second scenario shows the green beetle population to be the dominant type of beetle, taking up 90%, while the brown beetle population took up 10%. Over the years, things started to shift; the brown beetle population took up 70% of the population and the original dominant, the green beetle, took up 30% of the population. This is an example of evolution because the color of the beetles is a modification caused by a change in gene

For many years people have wondered why the antibiotics that are used so commonly nowadays are not as effective as they once were. Just like organisms evolve throughout time, resistance to certain things can also evolve. This resistance however is not something that happens naturally but rather is a man-made process which was caused via the misuse, overuse, and/or underuse of antibiotics (Davies 2010). The author Davies explains that there is no better example of the Darwinian notions of selection and survival than the spread of antibiotic resistance and how the bacteria have evolved with traits that make them that way. The more people use antibiotics, especially when not necessary, the higher the chance of bacteria in the body growing resistant to those antibiotics. Major problems have arisen such as cells becoming resistant to antibiotics because its selection pressure is reduced or eliminated. This means that one must counteract this by continually increasing the antibiotic concentration in proportion to the increased resistance (Rosenthal and Elowitz 2012).

Take for example MRSA (Methicillin-resistant Staphylococcus aureus), a S. aureus strain that was discovered in 1961 to be resistant to the antibiotic methicillin. Webmd indicates that MRSA has now grown its resistance from methicillin to “amoxicillin, penicillin, oxacillin and many other common antibiotics” (MRSA). This increase in resistance of a methicillin-resistant strain of S. aureus can be attributed to the increasing use and overuse of antibiotics, not only in the doctor’s office but also in agriculture. MRSA is only one of many antibiotic resistant strains of bacteria. New resistant strains are evolving rapidly. According to Dr. Ed Warren, “there are high levels of antibiotic resistance in bacteria causing common infections (e.g. urinary tract infections, pneumonia, bloodstream infections) in all regions of the world” (21).

Antibiotics have been the answer to many bacterial infections for the past 70 years (Antibiotic/ Antimicrobial Resistance). Antibiotics are “medicines used to treat infections or diseases caused by bacteria” (“What are Antibiotics?”). Antibiotics were prescribed to cure many diseases. Doctors prescribed many antibiotics during World War II. World War II was the start of the antibiotic era. Just when antibiotics were being greatly produced, bacteria started to evolve and became resistant to these medicines. What is antibiotic resistance? According to the U.S. Centers for Disease Control and Prevention, “Antibiotic resistance occurs when an antibiotic has lost its ability to effectively control or kill bacterial growth” (“General Background”). Improper use of antibiotics causes antibiotic resistance and has many effects associated with it. People may be drug abusers and this can cause resistance in the body. Some people will only take antibiotics because they believe it is the only way they will get better. When a person uses drugs to get rid of a sickness they may start to overcompensate, but when they do, the drug may have less of an effect because the body has become so used to the drugs medicine. That is because the bacteria has found a way to avoid the effects of the antibiotic.