First: Discussion Board: Natural Selection

In simplest terms, evolution can be defined as a change in allele frequency over time. A fact of nature is that allele frequencies for any given gene are always in a state of flux and for that reason evolution is a fact of nature. At the same time we have evolutionary theories that help us explain why allele frequencies change in the first place. For this section we will explore these evolutionary mechanisms.

The purpose of this discussion board is meant for you to share a news story that specifically deals with how evolutionary mechanisms are shaping nature around us. The article that you find will have to deal with natural selection.

Your job will be to do the following: Make sure you include all items.

• Give a short summary of your news article in simplest terms.
• As part of your summary include the trait that is specifically being selected for.
• Also, make sure you mention what is acting as the selective pressure.
• You will have to respond to two other student posts.

oFor example, a bacteria will evolve resistance to antibiotics if antibiotics are always present. In the absence of antibiotics, bacteria will have no need to evolve resistance to antibiotics. Its the excessive use of antibiotics that is selecting for bacterial genes that enhance a bacteria’s level of fitness.

Make sure you cite your work so that others can follow the news article.

Second;

Before you begin the assignment make sure you view the video “Gene Disorders Hit Amish Hard” and make sure you read this week’s PDF “Evolution and its Mechanisms”

Genetic Drift Webquest

Introduction

The Amish in the US began as a small group of Swiss-Germans that immigrated to the US in the 1700’s. Over the course of a few centuries they grew from a small founding population of 200 to a current population of more than 250,000. The most interesting thing about the Amish is that it’s a religious group that has remained culturally isolated and by extension, genetically isolated from the rest of the country. This genetic isolation from other humans has lead to an unprecedented amount of genetic disorders among the Amish.

Physicians were initially exposed to the genetic problems plaguing the Amish in the 1960’s. When the Amish began to reach out to the medial community doctors discovered that there were an unusual number of rare genetic diseases. One of these visible and rare genetic disease was called Ellis-Van Creveld syndrome. What was surprising to medical geneticists was not the presence of the rare genetic disease but rather how many Amish had the disease in the first place. Basically, the Amish in Lancaster County, Pennsylvania had more cases of Ellis-Van Creveld syndrome than all other human in the world combined! What was even more surprising was the fact that there was not just one rare genetic disease but rather dozens of rare genetic disease (In this context, rare genetic disease means that there may be less than 150 humans in the planet having the disease). Even more unfortunate is the fact that there are hundreds of other genetic disease associated with the Amish.

The big question that the Amish wanted to know was, why do they seem to have an unusual share of genetic disease when compared to the non-Amish and how do they stop those genetic disease in the first place!

What you are doing

• Your task will be to investigate a rare genetic disorder found among the Amish and to use evolutionary theory to both, help you understand why genetic disease can become common among isolated populations and to see how evolutionary theory can assist in curbing prevalence of genetic disease.

Before you begin your task make sure you do the following things.

• Read lecture notes on evolution. Especially the ones pertaining to Genetic drift.
• Watch video on Amish genetic desieses.

What you need to do

Before you begin this assignment, I recommend that you clearly understand what evolution is (a change in allele frequency from one generation to the next). Especially understand the founder effect. Make sure you use the information provided and give me informed ideas that are based on your understanding of the subject matter. For this assignment you will have to answer the following items:

• Pick and name a rare genetic disorder that is common among the Amish.Tell me how common the disease is around the world vs among the Amish? Give me numbers!
• Explain in evolutionary terms why the genetic disorder is found in unusually high frequencies among the Amish in the first place. In other words, why did some genetic variants that cause disease become unusually common over time among the Amish? Use the founder effect.
• Explain how the Amish might be able to curtail the incidence of your chosen genetic diseases using evolutionary knowledge. Use must explain this in evolutionary terms.
• Lastly, remember to cite all your work!