Are Mutations Harmfu1

Are Mutations Harmfu1 - Are Mutations Harmful?...

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Are Mutations Harmful? Acknowledgements eople often ask questions such as "Doesn't evolution depend on mutations, and aren't most mutations harmful?" and "Are there favorable mutations?". In this FAQ we try to answer these questions. Briefly: Mutations happen. They happen with great regularity. Almost all mutations are neutral. Of the remainder, benefit/harm depends on circumstances Biology is complicated; the jargon of the biological sciences is formidable. In this FAQ I have tried to answer common questions in simple language for the lay reader. At the same time I have tried also to provide material in greater depth for the reader who wants scientific substance. Q: Doesn't evolution depend on mutations and aren't most mutations harmful? A: No. Most mutations are neither harmful nor helpful. That's the short answer. The long answer is that mutations can be neutral (neither helpful nor harmful), strictly harmful, strictly helpful, or (and this is important) whether they are harmful or helpful depends on the environment. Most mutations are either neutral or their effect depends on the environment. Let's look at an example of a mutation which may be harmful or helpful, depending upon circumstances. English peppered moths come in two varieties, light and dark. Before the industrial revolution dark moths were very rare. During the worst years of the industrial revolution when the air was very sooty dark moths became quite common. In recent years, since the major efforts to improve air quality, the light moths are replacing the dark moths. A famous paper by H.B.D. Kettlewell proposed the following explanation for this phenomenon: Birds eat the kind of moth they can see the best. In England before the Industrial Revolution trees are often covered with light colored lichens. As a result light moths were favored because they were hard to see on the bark of trees whereas the dark moths were easy to see; birds ate the dark moths. During the worst years of the Industrial Revolution the air was very sooty so tree bark was dark because of soot. Dark moths were hard to see whereas the light moths were easy to see; birds ate the light moths. As a result the dark moths became common and the light moths became rare. Despite
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This note was uploaded on 11/14/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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Are Mutations Harmfu1 - Are Mutations Harmful?...

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