Tuesday, March 9, 2010
evolution stopping
Coyne writes that "every species is pretty well adapted, which means that selection has already brought it into sync with its environment" (133). Since species of animals are becoming so well adapted to the environment, will there eventually not be any more selective advantages in animals, leading to the end of evolution?
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I do not believe that evolution will stop because our environment is constantly changing, and many imperfections exist among all species, which leaves room for adaption and natural selection to allow them to further evolve. Our environment today has changed tremendously from what it was 4 million years ago when there was very little oxygen and no life forms, which shows that the environment is constantly changing and in order for species to survive and reproduce they must adapt to the environment they live in. It has also been argued over the past couple of years that global warming may become a problem in the near future. If this theory is correct, then the environment will change drastically from what it is today over the next several years. According to, http://www.stopglobalwarming.org/sgw_learnmore.asp, "super powerful hurricanes, fueled by warmer ocean temperatures are the “smoking gun” of global warming. Since 1970, the number of category 4 and 5 events has jumped sharply. Human activities are adding an alarming amount of pollution to the earth’s atmosphere causing catastrophic shifts in weather patterns. These shifts are causing severe heat, floods and worse." Also, there are many imperfections that are still present in species today. Many vestigial traits lack essential function in many species and can sometimes cause a potential injury to individuals due to their existence then if they were not present at all. Overtime these traits, if they are a large enough threat to a species, could become less present in the population due to natural selection that could possibly cause a species to evolve if enough years elapse. In some species with smaller wings, "if the wings are unnecessary, you can avoid injury by reducing them. In both situations, selection would directly favor mutations that led to progressively smaller wings, resulting in an inability to fly" (pg. 59). If these mutations were large enough to make a big difference in the species, then overtime, that species could evolve into a completely new species. Another issue that could cause evolution among species is the constant mutation of bacteria due to prescription drugs. Bacteria is constantly mutating, and drugs that were once effective towards certain diseases are no longer useful. "Scientists are dismayed to discover that some bacteria have become resistant to antibiotics through various alterations, or mutations, in their DNA. Hospitals have become a breeding ground for antibiotic resistant bacteria. These bacteria proliferate in an environment filled with sick people who have poor immune systems and where antibiotics have eliminated competing bacteria that are not resistant." (http://www.answersingenesis.org/articles/am/v2/n3/antibiotic-resistance-of-bacteria)If we cannot develop drugs quick enough to fight diseases caused by bacterial infections, then those individuals with genes that can fight off these infections could over time be selected by the environment to pass on their genes through reproduction, which could potentially evolve humans over thousands of generations. For these reasons, I believe evolution will not come to a stop anytime soon.
ReplyDeleteEvolution will not stop because, as Lexi said above, our environment is always being altered in some way. One way that we are currently changing our environment is with the development of new technologies that modify the genomes of different animals and plants. Genetic engineering is defined by the EPA as "a process of inserting new genetic information into existing cells in order to modify a specific organism for the purpose of changing one of its characteristics." Genetic engineering is especially popular in modifying our foods, called GMO's (genetically modified organisms). While there are many benefits that have been seen in genetically engineering foods such as increased resistance to pesticides, increased size, and increased nutritional value in plants and increased productivity in animals, there are some risks in genetically engineering foods. According to Nathan Batalion, ND, our ability to redesign organisms' genomes interferes with the process and the products of many years of evolution, and could potentially "breed new animal and plant diseases, new sources of cancer, and novel epidemics." Genetic engineering, however, goes beyond just food. It could also affect our ability to fight certain diseases and create new cures that are effective against current strains of antibiotic-resistant bacteria. According to evolutionist Johnjoe McFadden, "the role of genetic engineering means that we will be soon be entering a period of evolutionary dynamism – a result of being able to tweak our genome to, for instance, remove cancer and other genetic diseases." Therefore, our ability to change the genomes of different organisms will lead to some significant evolutionary changes in the future.
ReplyDeletehttp://www.epa.gov/OCEPATERMS/gterms.html
http://www.raw-wisdom.com/50harmful.
http://www.guardian.co.uk/commentisfree/2008/oct/08/evolution.genetics
Luckily, it is unrealistic that evolution would ever stop. Evolution is caused by adaptations over generations, while adaptations are genetic mutations that allow for increased survival. Since there are a finite amount of resources on the planet, there will always be competition for survival. With the exception of photosynthetic and chemosynthetic organisms, every living creature obtains its energy by consuming another living organism. Essentially, this creates an arms race between the consumer and the consumed. Over time, the prey adapts by building up defenses to the predators attack while the predator enhances its abilities that allow it to obtain the food. As an example, the matured Californian Ground Squirrel shows some resistance to the venom of the Rattlesnake, but not enough to survive consistent attacks. Over time, the squirrels with more resistance were able to survive, propagating the immunity gene; however, at the same time, the rattlesnakes with the most potent venom also were allowed to spread their genes. This arms race will go on until something else interferes with the two species and throws off this balance.
ReplyDeleteHumans are very good in disrupting the balance among species. People, as a group, have expanded into new ecosystems so rapidly that there is very little time for organisms to adjust to our presence. Although people are not there with the intent to kill other species, the competition for resources has immediately threatened the survival of other organisms. The organisms that are equipped with the talents most suitable for survival in our presence will be permitted to reproduce, which over time will lead to adaptations and eventually evolution. On the other hand, the weaker organisms will die out and their gene pool will cease to exist. Unfortunately, the rapid migration of people, as well as other invasive species (transported by people), has caused the extinction of some species. This is proof that the environments are constantly shifting, posing new problems in the survival and reproduction of many species. As well evolved as some species might appear to be to their current ecosystem, the constantly changing ecosystem means they wont necessarily be prepared to survive in the future, unless they adapt alongside the ecosystem. Therefore, unless the species desires death, evolution will never stop.