User:Sheela624/Conservation

Introduction
The human population hit seven billion people at the end of October in 2011. This number is only expected to increase, and estimations of our future population size indicate that the Earth will house nine billion humans by the year 2050. As the human population continues to increase, we simultaneously manipulate the environment around us, whether unintentionally or intentionally, to meet our growing needs. With a population so large, we require an even larger resource base. This base is so large that if every person lived a similar lifestyle to those in North America, we would need an extra two Earths to meet our needs. Humans exploit the globe’s available land, waterways, nutrient cycles, and the organisms that inhabit these areas to a large extent. Studies have shown that humans have altered up to fifty percent of the Earth’s land surface, humans have consumed more than fifty percent of the fresh water supply, and humans have caused the demise of twenty five percent of the world’s bird species. Though extinction is a natural activity, the human-mediated loss exceeds the natural rate.

Scholars argue that every single ecosystem on our planet has in some shape or form been altered by human influences. Our advancement through time has resulted in an advancement of technology, which has modified the environment in drastically unnatural ways. Human ventures such as the industrialization of agriculture, international trade, medicine, and fishing are just a few ways that we have altered the Earth as well as sustained our own species at the same time. The frequency and speed of anthropogenically-facilitated evolution sometimes surpasses those of natural selection by a great deal. These evolutionary changes can be seen in a variety of examples such as agents of disease, economically important organisms, commercially important pests, introduced species, and domesticated animals. Due to our global pervasiveness and its genetic consequences, humans have been labeled as the “world’s greatest evolutionary force”.

Disease Organisms
Antibiotics are a common means of defense against disease organisms. However, they have become so widely and sometimes carelessly used, that a number of bacteria have developed resistance to many powerful antibiotics. During the 1940’s, almost all Gram-positive bacteria, such as Staphylococcus aureus, were penicillin sensitive. However, sixty years later, these bacteria are now impervious to penicillin, and in fact, up to half of this category of bacteria have developed endurance against more potent antibiotics, such as methicillin. This specific development of resistance is commonly known as MRSA (Methicillin Resistant Staphylococcus aureus), and its increasing prevalence has prompted many reports in the media. Staphylococcus bacteria are resistant to a number of antibiotics. They developed resistance to vancomycin in 1986, and then in 1999, this genus developed resistance to Zyvox, which is an even stronger antibiotic. It is because of this continuous resistance that researchers have begun to search for more potent antibiotics and alternatives.

One reason that antibiotic resistance is so prevalent is because patients are not following through with a complete dosage. By treating a bacterial infection with only a partial amount of medication, you cannot ensure that all of the bacterial cells have been killed in your body. If any bacteria remain, they can evolve resistance to the antibiotic. In addition, a study has reported that up to thirty three percent of pediatricians in the United States alone, prescribe antibiotics to their patients even though the child has a viral illness that cannot be treated by an antibiotic. Resistance of antibiotics is also prevalent because bacterial cells are highly efficient in the process of conveying genes to other cells. In fact, bacteria have the ability to engage in conjugation as well as horizontal gene transfer, which mediate the transmission of novel genes.

Commercially Important Organisms
Humans can be very influential agents of selection when it comes to commercially important organisms. Cows and their genetic disposition have been greatly altered at the hands of humans. Due to an increased demand in milk production as well as the need for economic stability, dairymen around the world have drastically altered the composition of their herds. In the past thirty years, the UK has converted their herds from Friesian cattle to Holstein cows because these black and white cattle provide higher milk yields than other cows. In fact, ninety percent of herds in the UK are comprised of this North American breed. The availability of global Estimated Breeding Values, the worldwide trade of semen, as well as the efficiency of transporting Holsteins have all contributed to this high percentage of Holsteins not only in the UK, but around the world. The problem with this high occurrence of Holsteins is that there is a higher probability of inbreeding, which can result in a phenomenon known as inbreeding depression, random drift, and a decline in genetic diversity. In fact, in the United States, inbreeding occurs at a 0.2 percent rate every year, which leads to an incredibly low effective population size of fifty. In addition, this can have negative effects on the overall health, fecundity, and immunity of the entire cow population

About sixty percent of the world’s population is can be found around oceanic coastal areas. It is no surprise that humans also mediate evolutionary changes within the organisms that reside in these areas. The harvesting of seafood, especially fish, is a huge commercial enterprise. However, many fisheries are exploiting fish in such a way that it is deemed unsustainable. The reason for this is because commercial fisheries are extracting top predators, specifically larger sized fish, from these environments. In addition, the vast majority of fish are captured before they reach the age of eight years, and older fish are uncommon within these harvested communities. Studies have also discovered that death due to human-mediated harvesting exceeds natural means of death. Since commercial fishing is based upon size selection, it has caused fish populations to be comprised of both smaller sized and younger fish that reach sexual maturity at an earlier age. In addition, populations that have been subject to size selection are also examples of deteriorated genetic diversity, which can lead to more sensitivity in terms of environmental conditions or health maladies. All of these changes in life history traits are characteristics of stress, and they could suggest a possible dramatic downfall for fish populations in the future.

Commercially Important Pests
Chemicals play a large role in our modern lives. Seventy thousand different organic chemical compounds, which translates to one hundred million tons of chemicals overall, are produced each and every year. The United States alone uses seven hundred million pounds of pesticides every year in order to combat insects and other unwanted pests that could harm the nation’s agricultural industry This extensive use of pesticide is questionable due to the fact that most insects will develop resistance to a novel pesticide within ten years. In addition, in spite of the substantial reliance on pesticides, the United States still loses somewhere between ten and thirty-five percent of its agricultural production to insects Some may think that a new, stronger pesticide is the answer to solve such quick resistance, but the problem with this mode of action is that a number of insects are resistant to a variety of chemical compounds, so it proves extremely problematic. The same pattern of resistance holds true for the relationship between herbicides and weeds, except that weeds usually evolve resistance within ten to twenty-five years.

Costs
The total cost for human-mediated evolutionary change falls somewhere between thirty-three and fifty million dollars a year. However, economic costs as well as the genetic costs that are previously discussed on this page aren’t the only consequences of humans as pervasive agents of selection. The global community will also have to face social costs. Large sums of money are required to develop innovative and stronger pesticides, pharmaceuticals, and other agents of defense. As these costs rise, the consumers of such products will have to foot the bill, and those who reside within a lower socioeconomic status will not be able to pay for such expensive items. Therefore, the cycle of social inequality will continue to turn

Solutions
In terms of disease organisms, a method known as drug overkill can be employed to reduce to rate of evolutionary change. With this method, a variety of medications are used to completely hinder the productivity of any agent of infection or disease. By thoroughly hindering the fitness of these agents, there is no opportunity for evolution. This solution is also known as pyramiding when treating pests Another way to slow down evolution is through direct observation therapy. In this method, single amounts of medication are personally delivered to patients. In addition, the medical personnel will watch the patient ingest the medication. Therefore, this therapy allows for a higher probability of accordance. Testing for resistance before employing any method of action is another way to reduce the rate evolution. By testing for resistance, a physician can be more knowledgeable about which medications would be best for such circumstances, and better choices can be made.

In order to decrease resistance to herbicides, the agricultural industry should employ a new herbicide every two years, and when this change occurs, the new herbicide should have a different method of control. If this process is followed, any resistant strains that are formed in the first generation will not be preferential in the forthcoming generation. Mosaic selection, which utilizes various chemicals at distinct positions in the same area, is a modification of this cyclic scheme. Integrated pest management is another means to reduce the rate of evolution. In this method, chemical control is not the sole means of regulation. Instead, it is combined with other means of control, such as physical control, to combat pests and weeds. When these two controls are used, dependency on chemical compounds decreases. In addition, when physical control is employed, the population size becomes smaller, which means less individuals are subject to the chemical compound.

Possible Illustrations
1.) graph showing difference in price of grocery items before and after the boom of artificial selection

2.) flow chart showing the gradual resistance of viruses or bacteria to medications

3.) some illustration showing the difference in breeds of cows or dogs before and after artificial selection