quote:
"To an original population of 900 birds who are all homozygous aa, migrated 100 birds who are all homozygous bb. After a rough storm only 90 aa birds survived and only 10 bb birds survived. Relative to the original population, did evolution occur?"
Answer: Yes. "Before migration the frequency of allele a was 100%, after migration it was 90%, therefore evolution happened. The storm was not an evolutionary process and therefore did not change the allele frequency."
I don't understand how the mere movement of different alleles is an evolutionary process.
Evolution did occur, as far as relates to small, microadaptive changes. This is demonstrably proven by Darwin and his finches. But to me, I have to say to that, "so what?" That's really not a big deal. To me, this is really the extent of what evolution means. Speciation is what we're after here in order to explain the diversity of life, not the diversity of one specie. In fact, If evolution simply meant a change in allele frequency for any given population, there would be no controversy over it. With that portion of the argument everyone seems to be in total agreement.
If one specie becomes isolated, for what ever reason, a mutation can occur that is completely neutral. If it was reintroduced back into the main population, you might get different beak shapes or you might get a different color. But who cares about that? We already know about that. Just look at the wide variety of cats and dogs we have. If it wasn't that way, all animals would be carbon copies of their parents. That's obviously not the case.
Lets say we randomly selected some people for an experiment by using everyone with the last digit of their phone number. That way, we have no idea what eye color they will have until they come in. A certain percentage of people will have brown eyes, some hazel, some blue, and others green-- the last three being a product of a neutral mutation somewhere in the past. The alleles they inherited will determine what color eyes they have. And by counting the number of people with each eye color, you can determine the frequency of each allele in the gene pool. Dark eyes has been shown to be the most frequent, probably because it is dominant.
We obviously know that darker eyes are a dominant trait, and lighter eyes, a recessive trait. Because my both my wife and I have blue eyes, the likelihood of our children having blue eyes was pretty good. As well, both my parents and both my grandparents have blue eyes. Its the same on my wife's line. That increases the chances even more that they will come out blue-eyed. And both my children do in fact have blue eyes. My sister has blue eyes, but her husband has brown eyes. The dominant gene won, which was brown in both my niece and nephew.
What's really cool is finding people with one green eye and one brown eye. I also know a man where one hemisphere of both eyes is blue, and the other hemisphere is green.
I have heard an argument that eye, skin, and hair color are not necessarily the products of a neutral mutation, but are actually examples of beneficial mutations. The rationale is that dark skinned, dark eyed people can handle the heat better than lighter ones. They also say that blue eyes and light skin developed to combat snow blindness, because people with light eyes typically come from cold regions. If anyone wants to expound on that argument, it would be a cool topic.
So, anyway, if this where what people meant by "evolution," there would be no dispute. Unfortunately, this is not what evolution means. This is only one fraction of the theory. The rest, the part that is supported by theoretical biology, not hard evidence, is why this very web forum exists.
Faith is not a pathetic sentiment, but robust, vigorous confidence built on the fact that God is holy love. You cannot see Him just now, you cannot fully understand what He's doing, but you know that you know Him." -Oswald Chambers
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