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Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
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Author | Topic: MACROevolution vs MICROevolution - what is it? | |||||||||||||||||||||||||||
Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
If we did have a dog species that was "all the same"... how long do you (approximately) think it would take to produce differences in the population like long hair/short hair and strong smellers/weak smellers for 5 different traits? If you're talking about dogs left to their own devices, since they can all interbreed as far as I know, you don't need mutations at all, within a very few generations, give it a hundred if you want to lose all the characteristics of all the breeds, you'd have a mutt population with a mixture of different traits from all the breeds.
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Stile Member Posts: 4295 From: Ontario, Canada Joined: |
Faith writes: If you're talking about dogs left to their own devices, since they can all interbreed as far as I know, you don't need mutations at all, within a very few generations, give it a hundred if you want to lose all the characteristics of all the breeds, you'd have a mutt population with a mixture of different traits from all the breeds. We are talking about dogs left to their own devices.And yes, they can all interbreed since they began "all the same" (apart from half being male and half female... otherwise they would all die very quickly.) And, actually, we are only talking about mutations adding to the genetic variety... since they started out "all the same." They started out all the same, and then the population had some differences in it (long/short hair, strong/weak smelling ability...).All coming about through random mutations changing the genes. No selection. No environment pressures. Just a population living and reproducing and getting random mutations that eventually result in a few differences within the population.
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Taq Member Posts: 10085 Joined: Member Rating: 5.6 |
Faith writes: I feel it necessary to point out that the mutation has to occur in a germ cell because the usual reference to the constantly occurring mutations in every generation don't distinguish between those very very rare occurrences and the huge number of somatic mutations that don't get passed on. Why do you feel it is necessary to point out something that we all agree to, and have always agreed to? There are numerous studies demonstrating that humans have about 100 mutations that their parents don't have, and those are germ line mutations. Those are the numbers I keep referring to.
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Taq Member Posts: 10085 Joined: Member Rating: 5.6 |
Faith writes: If you're talking about dogs left to their own devices, since they can all interbreed as far as I know, you don't need mutations at all, Mutations do occur, though. They need to be part of your model.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
Exactly. It depends on if the population is large enough to recover from the population bottleneck or not. The cheetah seems to be having issues recovering. The bear does not. To recover from a bottleneck requires the ability to interbreed with others of the same species in order to add genetic diversity, OR depends on getting beneficial mutations that can build up the genetic diversity, but neither is happening with the cheetah. but neither is happening with the elephant seals either, and they have recovered their population enormously, just not their genetic diversity. Increasing population doesn't do anything toward increasing genetic diversity.
Therefore, the "mutts" would all be recognizable as the same sort of dog... just some have long hair, others short. Some smell better, others weaker... I don't think so, Stile. If some have longer legs AND long hair And different colored eyes you are talking about a different dog altogether, and you aren't going to get just those particular traits either, you are going to get unexpected other traits as well. Your mutt is not going to remind you much of the original dog at all. You seem to be under the impression that increasing genetic diversity contradicts my scenario, but it doesn't. What I'm talking about is the necessity of losing genetic diversity within a circumscribed new population in order to form a new variety or species from that population, since the alleles for traits that are not selected for that variety or species will be reduced and eventually drop out altogether. This all pertains to the specific daughter population that develops new traits as a result of new gene frequencies. To get the new trait picture for the population overall requires losing all the traits for the other species and varieties. That doesn't mean those traits are lost from the parent species, just from the daughter species. YOu really shouldn't be using dogs as your example since you seem to be talking about a wild species. I've been trying to get through your lists of examples and not getting very far. I gather you are trying to describe the series of populations I mention as reducing genetic diversity from population to population, and in some ways you seem to be getting the basic idea. But the change in gene frequencies from pop8ulation to population wouldn't just lose a trait here and there due to their becoming low frequency in the new population, it would also in many cases quite dramatically bring out entirely new phenotypes that are now high frequency in the new mix, and not necessarily the same traits in your examples. You might get a totally new fur color, a new muscular appearance, something really peculiar like bigger head and jaws such as appeared in the Pod Mrcaru lizard population. And when those appear you lose or reduce the alleles for other fur colors, for the less muscular type, for the smaller heads and so on. But I'm finding it hard to keep all the relevant variables in mind with your way of presenting things. The number of years you guess at is also distracting: I think such changes can occur over much shorter periods of time. It may take only thirty generations to form a distinctive look in one population, or maybe a hundred, but much more than that shouldn't be needed. Sexual recombination is going to mix up the genetic material with each reproductive cycle and if the founding population is fairly small that shouldn't take many years. You mention population size as if it had something to do with genetic diversity, but it's the size of the founding population that has most to do with the genetic diversity, not how large the population can become. You can have a huge population of genetically depleted animals such as the elephant seals, there's no necessary correlation between genetic diversity and the size of the population. As long as I'm not entirely sure what you think you are proving I'm probabgly not responding very clearly. Edited by Faith, : No reason given. Edited by Faith, : No reason given. Edited by Faith, : No reason given.
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New Cat's Eye Inactive Member |
YOu really shouldn't be using dogs as your example since you seem to be talking about a wild species. whoa...
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Taq Member Posts: 10085 Joined: Member Rating: 5.6 |
Faith writes: I don't think so, Stile. If some have longer legs AND long hair And different colored eyes you are talking about a different dog altogether, . . . Are humans with brown eyes an altogether different species than humans with blue eyes?
You seem to be under the impression that increasing genetic diversity contradicts my scenario, but it doesn't. It does contradict your scenario where evolution must stop when it runs out of genetic diversity. That is what we are arguing against.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
Faith writes:
If you're talking about dogs left to their own devices, since they can all interbreed as far as I know, you don't need mutations at all, within a very few generations, give it a hundred if you want to lose all the characteristics of all the breeds, you'd have a mutt population with a mixture of different traits from all the breeds.We are talking about dogs left to their own devices. And yes, they can all interbreed since they began "all the same" (apart from half being male and half female... otherwise they would all die very quickly.) Do you mean they can "all interbreed" with all the other kinds of dogs? If not you have the problem of maintaining reproductive isolation in your breed, and if so you are going to very rapidly get a populations of mutts that don't look anything like your original breed.
And, actually, we are only talking about mutations adding to the genetic variety... since they started out "all the same." They started out all the same, and then the population had some differences in it (long/short hair, strong/weak smelling ability...). All coming about through random mutations changing the genes. No selection. No environment pressures. Just a population living and reproducing and getting random mutations that eventually result in a few differences within the population. OK sorry, I wasn't getting this clearly at all. ALl that came from mutations you are saying. but it can't happen that way. Mutations are going to occur just here and there in individuals in a population, and without selection you aren't going to get changes in the population at large. I could go on trying to figure this out I don't see the point. I think you need to be a lot clearer than you're being.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
I'm not talking about humans but if you isolate a few dozen humans on a desert island for a few hundred years you will get an identifiable race of human beings, possibly with all blue eyes, depends what they started out with.
And yes, evolution does run out of genetic diversity in a daughter population that is woriing through a distinctive set of new gene frequencies especially if there is a series of selection events such as migration of small founding numbers from each new species. With every new daughter population you lose some genetic diversity and if it continues from selection event to selection event the end result would have to be the inability to evolve further for lack of genetic material. Yes indeed.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
Mutations do occur, though. They need to be part of your model. I agree with Percy. Mutations have very little to do with breeding.
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Taq Member Posts: 10085 Joined: Member Rating: 5.6 |
Faith writes: I agree with Percy. Mutations have very little to do with breeding. Breeding has very little to do with the long term evolution of wild species.
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Taq Member Posts: 10085 Joined: Member Rating: 5.6 |
Faith writes: I'm not talking about humans . . . Why would it matter what species you are talking about?
. . . but if you isolate a few dozen humans on a desert island for a few hundred years you will get an identifiable race of human beings, possibly with all blue eyes, depends what they started out with. The human species is not currently an "identifiable species"?
And yes, evolution does run out of genetic diversity . . . No, it doesn't. Mutations add genetic diversity. Edited by Taq, : No reason given.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
I said RACE not species.
We don't talk about races of humans as species, but for some reason animals are called species when they are only races or varieties. Mutations do NOT stop selection events from running out of genetic diversity in a daughter population that is working through a new set of gene frequencies. You could not get a new species or variety or breed or race UNLESS you reduce or lose all the alleles for traits not part of that species or variety or breed or race. Yes indeed, when selection is in operation to bring out a new species with a new phenotypic presentation you are definitely losing genetic diversity and the end result of that, if it reaches that point, has to be loss of the ability to evolve further. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
Breeding demonstrates how you get a new phenotypic presentation or a new species by losing alleles for other species. Happens in breeding, happens in nature. Mutations may slow it down but the development of a new species REQUIRES the loss of alleles for other traits.
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Taq Member Posts: 10085 Joined: Member Rating: 5.6 |
Faith writes: Mutations do NOT stop selection events from running out of genetic diversity . . . Yes, they do. Mutations produce new phenotypes which increase genetic diversity.
You could not get a new species or variety or breed or race UNLESS you reduce or lose all the alleles for traits not part of that species or variety or breed or race. Are you saying that humans are not a species because there are humans with brown eyes and blue eyes? Would one eye color need to replace another before humans can be considered a species?
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