A question about evolution

This is a question from my ecology course about evolution:"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 is a change in the allele frequency of a population.The percentage of the allele changed in the population so evolution occured.

Did it? It's not clear that the two groups of birds aren't part of the same population to begin with.If they were, then no, evolution did not occur because allele frequencies didn't change as a result of selection.Really it comes down to what is meant by "original population."

quote:

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"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?"

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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."

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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.

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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

What would you call it if the original 900 birds, with 100% aa, were joined by 100 birds of bb thus the population increases to 1000 and the frequency of the aa allele drops to 90% with no selection taking place? (forget the storm altogether)ABE: genetic drift?But WRT to the OP, the question is not unclear. If the migrating birds were a part of the original population, then the frequency of aa would have been 90% not 100%. So it is safe to assume that the migrating birds were NOT a part of the original population.The population increased before it decreased from the storm. The original population was 100% aa, after the storm after the population increased, it was 90% aa. WRT the original population, of 900 birds, the allele frequeny changed. I guess it comes down to if the increase in population combined with the storm still counts as selection.Edited by Catholic Scientist, : see ABE

but that is what evolution means (small 'e' evolution, at least)Thats why its so funny when creationists say that evolution has never occured, because all it is is a change in the allele frequency, which happens all the time.

Sure, small 'e'. As to evolution being so simplified as to be able to get a human from his pond scum cousin, no, it means so much more than just allele frequencies.

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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

Why?

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Aslan is not a Tame Lion

Well, what would you call it if my sister drives down from Minneapolis and nobody gets killed along the way?I mean, did my family just get larger? No, she was part of the family all along, just a geographically distant part of it.We don't know where these additional birds came from. The fact that they're so easily absorbed into the main population in the first place indicates to me that we're not supposed to view them as different species or different populations merging - merely, it's a goofy explanation for why there's homozygous individuals for both traits but no heterozygotes.It was all one population to begin with. Since allele frequencies weren't changed by the storm, no selection happened. So no evolution happened.

No, it doesn't, because the only difference between a human and some pond scum is different genes. Genes make the organism.Hence, any natural feature that can change the contents of genes is sufficient to result in pond scum eventually giving rise to humans, because all it takes is changing genes over time.

Well, that IS a common misconception.You can get any population of a species to evolve into any other species just by changing the frequency of the alleles. Well, maybe not any species, there's probably exceptions. But its all in the genes and what they code for. Change them around enough and you could get all kinds of wacky stuff, even humans.The big 'e' evolution includes the mechanism by which the allele frequencies change, but it really isn't very much more than the little 'e' evolution, WRT allele frequency changes.

Because induced mutations in developmental genes often lead to catastrophic deformity or it is completely neutral. That would indicate that they cannot even change on the species level. Aside from which, evidence of beneficial mutations are so rare, and have yielded almost nothing in the realm of evidence, that it is still within the realm of theoretical biology, not hard fact.I think if macroevolution were such a widescale phenomenon that unambiguous evidence of such should be as plain as day. Just saying that macroevolution is a magnification of microevolution doesn't make it so.

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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

In the wise words of Jerry Maguire, "Show me the money."

I don't see what your getting at.We define the populations.Is there a term for the change in allele frequency from of a change in the definition of the population? What abut the merging of two populations? <-- questions I would have included her in the original population. The OP's question was worded to not include the 100 migrating birds in the original population. Well it wasn't one population to begin with so now what is your answer?

I ain't got it.