Artificial Selection

Artificial selection has resulted in plants that are more disease-resistant, cows that produce more milk, and racehorses that run faster. One must wonder what will come next. In the blog entry answer the following question - Under what circumstances should humans be artificially selecting plants or animals, if any?

Artificial selection is human intervention in animal or plant reproduction to ensure that certain desirable traits are represented in successive the next offspring and future generations. Because the offspring also carry the genes for these traits, this process causes the genes for advantageous traits to become more common in populations and the genes for disadvantageous traits to become less common in populations. This process is the exact opposite of natural selection. A specific plant or animal is chosen because it has a specific trait that the breeder desires and the offspring will inherit. The plant or animal is then bred with another of its kind with a similar trait, resulting in offspring with a higher potential to display the specific trait. Artificial selection is also known as selective breeding.

Charles Darwin used the term artificial selection twice in his book, On the Origin of Species. Charles wrote about the complex and beautiful things he believes that humans can create through artificial selection (first reference) and described the reasons for differences in animal breeds in countries with different development levels (second reference). Charles Darwin never plainly defined the term artificial selection in his book. Artificial selection can have great effects on population of a species and their ability to adapt to living standards, and alter their behaviour and appearance is nothing similiar to their ancestors. I feel when we alter or create species for our own benefit, it is as if we are playing God. We’ve gotten so used to animals performing to our liking, and developing to our preferance that at this point in time to change this would be a disruption in our lifestyles.

Inbred offspring are one of the dangers of too much artificial selection. Some traits may be so rare that they only exist in 1-2 family lines. If this occurs, two members of the same line (meaning relatives) may have to be bred together in order for the trait to be expressed. In animals, this can result in genetic defects and health problems. By artificially selecting, we aren’t doing any good for most animals; they lose traits we think might be useless but in the long run mean a lot.

I think under certain circumstances artificial selection is okay, as long as it is not to the extent where the genetic changes are harmful to the development of the species. There is no need for us to stop artificial selection entirely because in some cases it is not harmful to an extreme or at all. Even though it may seem selfish of us to alter different species to behave in a manner that is convenient for us, it is for the benefit of the human race that we do these things, but also what we do must be in harmony with the environtment. So we should be able to select artifically, but only to a certain extent.

Sources:

http://www.wisegeek.com/what-is-artificial-selection.htm

http://evolution.berkeley.edu/evosite/lines/IVAartselection.shtml

http://en.wikipedia.org/wiki/Artificial_selection

http://en.wikipedia.org/wiki/Cockapoo

Are Humans Stewards of the World?

Question: Many scientists consider humans as the most invasive species, as humans can greatly change an environment and impact living things that reside there. Are we being stewards of the world? Take a look at an issue in which human intervention has positively or negatively affected the biodiversity of our ecosystems.

Humans, stewards of the world? I'd say humans are "stewards of the world - in training" ! I believe that most humans do not understand the extent of the damage we cause to the earth on a daily basis. We are now starting understand and realize that what we are doing is extremely harmful, and will eventually lead to the complete destruction of the Earth. ONe major issue we are having with our environment is one that most people have heard something about, which is "global warming".

Global warming is an increase in the earth's atmospheric and oceanic temperatures widely predicted to occur due to an increase in the greenhouse effect resulting especially from pollution (www.mdbc.gov.au/subs/The_River/glossary.html).

Carbon dioxide, methane, nitrous oxide, refrigerants, and other gasses create a greenhouse effect by trapping heat in the troposphere. This increases Earths heat because the sun's rays are allowed into the troposphere but the heat from these rays aren't able to escape.

The Earth's atmosphere is consists of five different layers. The layer closest to the surface is called the troposphere. The second is the stratosphere, the ozone layer is also found here. The ozone layer is Earth's natural protection for all life forms, shielding our planet from harmful ultraviolet-B (UV-B) radiation. UV-B radiation is harmful to humans, animals, and plant life. The third layer is the mesosphere. Most meteors burn up when they enter this atmosphere. The fourth layer is the thermosphere; this is where the International Space Station orbits. Auroras also occur in the thermosphere. The final layer is the exosphere; it is mainly composed of hydrogen and helium.

Certain industrial chemicals including ozone depleting refrigerants, and methyl bromide, a deadly pesticide used on crops, are destroying the ozone layer. When the stratosphere is very cold, ozone depletion gets worse. Because global warming traps heat in the troposphere, less heat reaches the stratosphere, which makes the stratosphere colder. Greenhouse gases act like a blanket for the troposphere and make the stratosphere colder. In other words, global warming can make ozone depletion much worse. Minor problems of ozone depletion can have

major effects; every time a small amount of the ozone layer is lost, more ultraviolet light from the sun reaches the Earth. This increase in ultraviolet light radiation (UV-B) causes skin cancer, cataracts and immune suppression in both animals and humans. UV-B also damages plants including forests. Oceans will be affected as well. The most basic microscopic organisms such as phytoplankton (an alga is a type of phytoplankton which is the building block of the oceanic food chain) may not be able to survive. If phytoplanktons are unable to survive, all of the other animals that branch off from phytoplankton in the food chain would become extinct aswell. The planet's climate could also be affected by depletion of the ozone layer. Wind patterns could change, resulting in climatic changes throughout the world.

The ozone layer has been discussed multiple times by millions of people. Depletion of the ozone layer is due to the release of CFCs (chlorofluorocarbons). CFCs are used in refrigerators, home insulation, plastic foam and throwaway food containers. People began to realize that CFCs caused a disturbance in the stratosphere. In the stratosphere, the chlorine atom is removed from the CFC and attracts one of the three oxygen atoms found in the ozone molecule. This process continues, and just a single chlorine atom can destroy over 100,000 molecules of ozone. In 1984, an ozone layer “hole” was discovered over Antarctica. It threatened the living things found there. Even if CFCs were to be banned there would still be problems. There is no way to remove the CFCs that are present in the environment.

There are so many things affecting our ozone layer, if we never began using CFCs would there still be holes in the ozone layer? Well we'll never know. The best we can do is stop using CFCs, and do everything we can to keep our planet clean of harmful toxins.

We are on our way towards become good stewards of the world, it just takes time.