A question about evolution

Evolution is a change in the allele frequency of a population.The percentage of the allele changed in the population so evolution occured.

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.

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.

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.

You totally misunderstood the question.

I was under the impression that the birds were all the same species and that they were divided into two populations. Then the two populations were merged and selected against by the storm. The percentage of the alleles was different after the merger and selection. We can't redefine populations? Does the most basic definition of evolution include the flow of genes? Can't allele frequencies change without gene flow when some individuals die?

Yes just by proximity and without any gene flow. We draw the lines for the populations. If we move the line or if they cross the line then the population changes. Then how are populations defined?Its all reletive to what you want to be talking about. All of the dogs in Bob's backyard, all the dogs in Missouri, all the dogs in the U.S., all the dogs on the planet. They are all the same species regardless of where we draw the lines, but we can still draw them and talk about them as different populations.The allele frequency of the dogs in Bob's backyard could change and that population could be said to have evolved. This has also affected the population of dogs in Missouri, which has also evolved. But what about the population of dog's in Ted's backyard. They haven't had any changes in their allele frequency, but they can also be included in the Missouri population, which has.Is there a term for the situation where the allele frequency changes because of the population definitions?You're being defensive and avoiding answering an honest question that I would like to learn the answer to. It doesn't always have to be an argument, well, apparently with you it does Depends on the definition of the population. Oh, I think they do. That's retarded, it doesn't change my species, it changes the population I belong to. I would become a part of the population of people at the zoo, not some new species altogether

Yes we can, by our definition of evolution. This certainly doesn’t affect what is actually physically occurring but our models might change the representation of the occurrence by the way we have defined the model. Yes, but we do it nonetheless, even if it is just in the hypothetical.On a global scale, all species are constantly evolving (although there might be exceptions, I dunno). What we can do though, is define smaller populations, or sub-populations, of the global population of a species. We can use these to ”zoom-in’ on specific groups to observe what modification and selection they are experiencing. These sub-populations may or may not be having changes in their allele frequencies. A small group of some species might be in stasis while the species on a global scale is not. When we zoom back out, the small group that was not evolving becomes part of the larger group that is evolving. On a global scale, not all sub-populations have gene flow with each other. Can they not be a part of the same population for that species as a whole, on a global scale? Why does you example talk of two different species when exemplifying two populations of the same species? I can never become a part of the ant population but it is possible for the new individuals to flow genes with the old ones.If populations are defined by gene flow alone, then for some species, there cannot be a global population because they are unable to have gene flow with member ”across the globe’. If one sub-population of that species has a selective force that changes the allele frequency, then only a fraction of that species is evolving? The species, as a whole, is evolving too, yes? What about the sub-population across the globe, have they not evolved? Even if we consider them a part of the whole species?I’m not trying to prove you wrong or argue, I’m trying to better understand some of the concepts and definitions involved in evolution. Not if the zoo is in Australia. Well if you define the population to include me then of course the population doesn’t change by me joining it. The question was for a population that didn’t already include me. See, I think that we could say, WRT the population in the room, evolution has occurred when I walk into the room, because the allele frequency has changed. That sub-population has had a change in its allele frequency. Now, this really doesn’t offer us anything useful in the real world, but it seems to fit the definitions. I realize that doesn’t make sense but I don’t realize where my misunderstanding begins and the faults in the definitions end.I think that I’m using too simple a definition of ”evolution’. But I think that is too strict of a definition because of the generation to generation part. If a selective pressure eliminates a bunch of alleles of a single generation, hasn’t that population evolved, by definition? Its defined here over successive generations as well. Is that really the current accepted definition? If so, then if a selective pressure eliminates a bunch of alleles of a single generation, that species has not evolved until the next generation is born. But then, generation for some species is not defined well enough to determine when evolution has actually occurred.Now I’m starting to confuse myself and I’m getting sick and tired of typing. Time to hit the submit button.

I agree. I don’t think that the ”walking into the room’ situation (I hope we’re both on the same page with that) constitutes actual evolution but it seems to me that according to the bare bones definition of evolution, that the ”walking into the room’ situation might count as evolution, by definition. I guess my point is that the boiled down definition of evolution is too simple because it can include situations where non-evolution can be included. Sort of the same way that the boiled down definition of species gets into problems. Wouldn’t that be different populations? Aren’t there species that have different populations that are different reproductive communities but are still the same species? understood WRT the question in the OP, the two populations of birds are assumed to be the same species though. You mean like your claim that I’m part of the Australian airport population just because I could fly over there and mate if I wanted to. But its easy for you to consider these populations of birds as evolutionarily-irrelevent. What’s the distinction? The ease of interaction? The one bird population flew to and joined the other. busted . but there is a point.It exemplifies the problems with the definition of ”species’ ”population’ and ”evolution’ and how confusion and misunderstanding are easily evoked. I’m honestly trying to better understand how I should, um, understand the meanings of these words. It seems that the stripped down definitions that I currently accept have some problems. Sure, me too. And the argument you’ve presented in this thread would certainly have convinced me to reimburse you those points if I was the prof.The question, itself, has its own problems. I already took biology. One of the issues I have, I guess, is that sometimes things are presented as ”rigidly drawn’ and well defined, but when we apply some of the definitions to real life scenarios, the fuzziness is brought out. I don’t think biology classes admit enough that they don’t have all the answers and that some things are still pretty fuzzy. Awe, thanks for the compliment. Yes, it was and I hope kalimero posts the prof response and explanation of the question.Thanks for the discussion so far, I feel like I getting a better understanding

any word from the prof?

Oh, I thought there was some question in this thread that you were gonna ask him. I didn't see it at quick glance.Maybe you could print out the thread and let him read it. There were a couple arguments made as to why this does NOT count as evolution that might interest him. Or at least print out just the arguments against his 'yes' answer to the quetion.