Download Describe an example of how natural selection influenced the

Describe an example of how natural selection influenced the evolution of a particular
species. Include outside sources if applicable. Review a classmate’s post and discuss
additional conditions that might have contributed to the selection process.
The peppered moth is a classic example of how natural selection has influenced the evolution of a
particular species. Prior to the industrial revolution, the light-colored form of the moth known as typica
was the predominant species in England. However, during the period of industrial revolution, the
environment was changed due to the massive increase in pollution which resulted in soot collecting on
walls and buildings and turning them into a darker color. It was during this period where it was noted
that the predominant moth in England was no longer the typica species but in place was the
carbonaria species which was dark-colored. The reason behind this change was that the peppered
moth underwent mutations through natural selection for a dark phenotype. This is because prior to
industrial revolution, the light-colored moth could camouflage itself by hiding on similar colored tree
barks. However, the pollution during the revolution changed the color of the environment; hence the
light-colored species was easily detected by predators, which is why the moth evolved to be darkcolored to blend in the darker surroundings. In this case, the natural selection process is for the
protection against predators.
After reviewing my classmate’s post, I understand there are other factors which can contribute to the
selection process. For example, some species mutate to find food for survival. According to Darwin,
the giraffe which originally had a short neck, mutated to have a long neck over time so that it can
avoid competition for food with animals especially during droughts and have the ability to reach for
food where the other hoofed animals cannot. To conclude, there are many reasons why natural
selection takes place, and it occurs so that it can be advantageous to the particular species.
Sources:
http://www.millerandlevine.com/km/evol/Moths/moths.html
http://www.biology-online.org/2/11_natural_selection.htm
http://www.natureinstitute.org/pub/ic/ic10/giraffe.htm
Given Darwin’s theory of evolution, what scientific evidence best supports evolution by
natural selection?
In my opinion, Darwin’s theory of evolution was best supported by the fossil record of
change from previous species, the genetic changes in living organisms over generations and
centuries. Firstly, fossil record demonstrates how organism evolved over the Ages. Through the
shifts in geological time, the organism either evolved or died out. Humans are the very example
of how a species can evolved from its ancestors, the apes, to have a different number of
chromosomes. The difference in genetic components is the reason why we are so different
from our ancestors, compared with the apes, we have higher intelligence, however their muscle
strengths are much stronger than ours. This is an example of natural selection at work, humans
evolved to have higher intelligence so as to adapt to the society while apes evolved to have
strong arms so that they can survive in their habitat like the orangutans in the forests.
The theory of adaptive radiation is also a support for fossil record change. It explains
why species will evolve over the years. In the case of Darwin’s finches, we know that Charles
Darwin observed that the species of finches on the island were very similar except for the
differences in their beak on Galapagos Island. These differences in beaks can be explained by
the increase in competition for food by the finches on the island. In order to survive, the finches
adapted and modified their beaks due to mechanisms of natural selection so as to take
advantage of the different food source in their habitat. Hence, this is an example of how a
species can evolve to form different species with different genetic components, as illustrated by
the organisms in the fossil records.
Websites:
http://anthro.palomar.edu/evolve/evolve_3.htm
http://www.evolutionpages.com/chromosome_2.htm
http://www.agiweb.org/news/evolution/fossilrecord.html
http://www.biology-online.org/2/15_adaptive_radiation.htm
http://people.rit.edu/rhrsbi/GalapagosPages/DarwinFinch.html
http://www.nature.com/nature/newspdf/evolutiongems.pdf
Humans shape their environment in ways that other organisms cannot. Are humans
subject to the same pressures of natural selection as other organisms? Why or why
not?
Like other organisms, humans are subjected to pressures of natural selection. Darwin’s
theory of natural selection suggests that individuals will mutate to achieve genes that are more
advantageous to the species. From the evolution from the apes to walking on two limbs and
developing larger brains, these are all examples of natural selection at work. Research has
shown that ‘9 percent of the human genes examined are undergoing rapid evolution’. However,
even though humans under natural selection, they are not subjected to the same pressures facd
by other organisms. This is because humans have developed higher intelligence level, and unlike
other organisms that have to make changes to suit the environment, humans can change the
environment to suit themselves. For example, we have developed weapons and tools to fight
against predators, and has hence distorted the food chain where we have contributed to most of
the diet of animals like tigers, lions and snakes. The use of technology also means that it no
longer has to be the fittest who will survive. For example, infertile couples are now able to
reproduce due to technology and stem cell research also promises the human race of the
possibility to eradicate harmful genes and ‘pick’ the best genes for their children. Thus, we can
see that the human race has been doing a lot of things to combat negative selection and improve
positive selection at a rate faster than any other organisms. To conclude, even though we are
under the pressure of natural selection as other organisms, we are under less pressure due to
modernization and the use of technology.
Sources:
http://scienceweek.com/2004/sa041029-4.htm
http://www.livescience.com/health/051102_natural_selection.html
Provide an example of convergent and divergent evolution, adaptive radiation, and
co-evolution. Then, respond to the following: Choose one of the examples you provided
and discuss the implications this example may have for future humans.
Convergent evolution occurs when two or more species of different ancestries evolved to have
similar features, for example, birds and bats both have different ancestors however they have
evolved to have wings and the ability to fly.
On the other hand, divergent evolution occurs when a group with the same ancestries developed
into new species with distinct differences due to the demands of the environment. An example
will be the red fox and kit fox. The red fox has a red coat to blend in the forest habitat, while the
kit fox has a light coat to blend in the desert habitat.
Adaptive radiation is the speciation of an organism due to factors such as changes in
environment. An example will be Darwin’s finches in the Galapagos Island which developed into
different species with different beaks to take advantage of the different food resources on the
island and lengthened the lives of the species.
Co-evolution is the change in genetic component of a species in response to the change in
genetic component of another. For example, to prevent parasites from feeding on it, some plants
like the Venus flytrap and the mimosa plant have developed traits that can either feed on the
pests or protect it from the pests.
Out of these four processes, divergent evolution will be the one which will have the most impact
for future humans. Firstly, divergent evolution is already demonstrated by our racial diversity.
With increasing inter-racial marriages, our gene pool will become more complex; this can have
adverse impacts on heath as more will have to be done to understand the different needs of
different race groups. On another level, increase in racial diversity can also lead to
misunderstandings and miscommunication should toleration and understanding not be bridged.
Sources:
http://science.jrank.org/pages/2608/Evolution-Convergent.html
http://science.jrank.org/pages/2609/Evolution-Divergent.html
http://biomed.brown.edu/Courses/BIO48/27.Coevolution.HTML