Download Biology Final Paper BIOL 1010

Artificial Selection
Summer McNeely
Evolution can happen through natural selection or artificial selection. In order to understand
artificial selection, we must first understand natural selection. Changes occur when a species has to
adapt to its environment to survive. Thomas Malthus proposed the idea that death and famine are
inevitable. Humans and animals reproduce at a rate that creates a constant struggle for resources.
Nature then takes over and only the strongest can find food, fight off competition, and reproduce.
Mother Nature may seem cruel to kill off the unadaptable, but it is for the best interest of the future
inhabitants. The next generation becomes strong and better adapted to the environment.
Charles Darwin (1809-1882), studied Finches in the Galapagos Islands and discovered that the
sizes of the bird’s beaks varied according to the living conditions. As the birds moved from island to
island, their environment changed. They needed to adapt to the seeds, nuts, and insects they were
eating. Long pointy beaks were better for eating soft food, such as fruit whereas the bigger tougher
beaks were better from cracking seeds open. Through natural selection, the birds who were better
suited for the environment lived and reproduced. Through many generations, the birds had changed so
much from the birds they originally descended from that they evolved into different species. Today
there are 14 different species of Darwin’s Finches. They don’t just vary in beaks sizes, they also vary in
diet and in the songs they sing.
Natural and Artificial selection happens in response to a selective agent. Tin natural selection,
the selective agent is the environment; it chooses those who have advantages over others to survive. In
artificial selection, humans become the selective agent. Humans choose which genes will be passed
down to the next generation of offspring.
A perfect example of Artificial Selection is Dog Breeding. Dogs have been domesticated for
somewhere around 15,000 or 20,000 years. They descended from wolves. The remarkable thing about
our society’s obsession with breeding dogs is that in just the past couple hundred years, between 350
and 400 dog breeds have emerged.
Dog Breeding has undermined natural selection and given birth to a plethora of variations.
Traits and mutations that would have died off in the wild have been fostered. Think of the variation of
sizes in different dog breeds, from Great Danes, Mastiffs, Saint Bernards, to Pugs, Terriers, and Shih
Tzus. If humans had the same range of variation in height as dogs did, the tallest would be about 31 feet
tall, and the smallest only about 2 feet tall. Part of the reason why such drastic differences are bred in
dogs is for the fame of the breeder. The more distinct the dogs appeared, the better the likelihood was
that it would be named an official new breed.
While human have been tampering with dog breeds for ages, we have also been playing with
genetics. Dog genes with large impact have been favored over smaller genes with less impact. So, genes
in dogs are much easier to manipulate because they are controlled by less gene regions than humans.
For example, the trait for floppy ears instead of erect ears is a difference in only one gene region.
Human height, on the other hand, is controlled by around 200 gene regions. Scientists have seized this
opportunity and have mapped mutations in particular genes in dogs, many of which have human
counter parts.
In some areas of the world like Egypt, Uganda, and Namibia, there are partially domesticated
dogs. The DNA of these dogs are as closely related to wolves as they are to fully domesticated dogs.
These dogs give us a unique look at what dogs looked like thousands of years ago, before so much
selective breeding had taken place. Adam Boyko was a post doc a Cornell University who studied these
interesting dogs. He described, “When you are looking at village dogs you have something more akin to
natural selection, albeit in an environment that’s managed by humans.” Studies on the genetic diversity
of these village dogs gives us a better understanding of where the earliest dog breeding began.
Originally we believed it began in East Asia, but after Boyko’s studies in 2009 he found that village dogs
of Africa were just as diverse as the East Asia ones.
Another interesting experiment of artificial selection took place in the Soviet Union in the
1950’s. Two brothers, Dmitry and Nikolay Belyaev had questions about how dogs were domesticated
from wolves. However, since the biology establishment was under Joseph Stalin, Mendelian Genetics
research was forbidden. At the time, the study of genetics was considered a fake science. When they
defiantly continued their research, Nikolay was exiled to a labor camp where he died years later. Dmitry
Belyaev was determined to continue, but he had to do so in secret. Stalin died in 1953, but Belyaev
remained discreet because the strict Communist control could still jeopardize his genetic experiments.
Belyaev thought the best way to find answers to the questions he had would be to try to duplicate the
process with an animal similar to a wolf: the Silver Fox.
Through the process of selective breeding, Belyaev looked through groups and groups of foxes
to find just 130 that were the calmest to humans. Most were aggressive, biting and snarling, but there
were very few that were not. The docile foxes were then bred with other docile foxes. After only four
generations the foxes were tame enough to jump into the arms of the researchers. The similarity
between the tame foxes and tame dogs was uncanny. One of the researchers took a fox home with him
in the 1970’s and let it off the leash. When the man whistled and yelled the fox’s name, it quickly came
back. The foxes did not just tolerate the human interaction, they craved it! One of the researchers
described them as treating all humans the same way: as a potential companion. The experiment shows
that domestication of foxes is nature, not nurture. If a wild fox cub was raised by a tame mother, it
would never learn to be tame. It is a process of generations of selective breeding.
As the foxes became tame through the generations, their physical traits changed as well. Their
ears got floppy, they got white spots on their coats, they would bark, and their tails got bushy. This was
something that Charles Darwin had noted. Domesticated animals tend to look more juvenile and
appealing to humans. These domestic phenotypes exist in other animals also, like pigs, cows, chickens,
and even fish.
The Merriam-Webster Dictionary defines evolution as a process of continuous change
from a lower, simpler, or worse to a higher, more complex, better state. Jean -Baptiste de Lamark
studied fossils and saw that species have changed from simple, to complex. Whales, for example, at one
time lived on the land. We can see this from the fossil history. The study of fossils can seem so hard to
grasp because the geologic time scale is hard to grasp. The first humans appeared about 1.8 million
years ago. The first life forms appeared about 3.9 billion years ago. Trying to wrap your mind around
the time frame of the earth’s history can be incomprehensible. That’s why artificial selection can be such
a useful tool. We can watch history in fast forward.
Artificial Selection has greatly benefited our society. It has been used in animals to study
domestication, as we saw with the Russian Fox Experiment. Studying genes in dogs have helped us to
learn about the human body. Selective breeding in farm animals has allowed for better quantity of food
production. Plants have been artificially bred for thousands of years. Advances in crop breeding has
hugely helped combat world hunger, and help with the production of medicine.
Works Cited
Cromie, William J. "How Darwin's Finches got their Beaks." How Darwin's finches got their
beaks. July 2006. Harvard University Gazette. 11 Apr. 2013
<http://www.news.harvard.edu/gazette/2006/08.24/31-finches.html>.
Ratliff, Evan. "Taming the Wild." National Geographic. Mar. 2011. The National Geographic
Society. 10 Apr. 2013 <http://ngm.nationalgeographic.com/2011/03/taming-wildanimals/ratliff-text/1>.
Ratliff, Evan. "Mix, Match, Morph: How to Build a Dog." National Geograhic 19 Jan. 2012: 35-51.
Mader, Syvia S. Concepts of Biology. 2nd ed. The McGraw-Hill Companies, 2011.
Col, Jeananda. "Geologic Time - EnchantedLearning.com." Geologic Time EnchantedLearning.com. 1998. 11 Apr. 2013
<http://www.enchantedlearning.com/subjects/Geologictime.html>.