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Member (Idle past 1434 days) Posts: 20714 From: the other end of the sidewalk Joined: |
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Author | Topic: MACROevolution vs MICROevolution - what is it? | |||||||||||||||||||||||||||||||
Coyote Member (Idle past 2135 days) Posts: 6117 Joined: |
From post 396:
Outline of Biblical Usage: Ah, so modern humans and chimps are in the same "kind" then. Got it!Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge. Belief gets in the way of learning--Robert A. Heinlein In the name of diversity, college student demands to be kept in ignorance of the culture that made diversity a value--StultisTheFool It's not what we don't know that hurts, it's what we know that ain't so--Will Rogers If I am entitled to something, someone else is obliged to pay--Jerry Pournelle If a religion's teachings are true, then it should have nothing to fear from science...--dwise1 "Multiculturalism" demands that the US be tolerant of everything except its own past, culture, traditions, and identity. Liberals claim to want to give a hearing to other views, but then are shocked and offended to discover that there are other points of view--William F. Buckley Jr.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
Your scenario is alien to me, your terminology is alien, and I'm going to have to come back to it later anyway. Also, mutations, which is apparently your answer to what would bring about speciation, can't possibly bring about speciation, that takes selection, but just as a matter of fact I'm not focused on speciation, just any homogeneous population brought about by selection: species, variety, whatever.
I'll be back later. Edited by Faith, : No reason given.
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herebedragons Member (Idle past 886 days) Posts: 1517 From: Michigan Joined: |
I will come back on later and explain in detail the comparison between the two processes. So let me get to that before you respond. Thanks.
HBDWhoever calls me ignorant shares my own opinion. Sorrowfully and tacitly I recognize my ignorance, when I consider how much I lack of what my mind in its craving for knowledge is sighing for... I console myself with the consideration that this belongs to our common nature. - Francesco Petrarca "Nothing is easier than to persuade people who want to be persuaded and already believe." - another Petrarca gem. Ignorance is a most formidable opponent rivaled only by arrogance; but when the two join forces, one is all but invincible.
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herebedragons Member (Idle past 886 days) Posts: 1517 From: Michigan Joined: |
Well... seeing as how Faith has NEVER argued that "new kinds come into existence" and nothing I've said in the last day has any thing to do with "new kinds coming into existence" your point is even more obscure.
It seems you think you have a winning hand when you don't even know what game we're playing. "Full house! nines over tens!!!" Uhmm... we're playing Euchre." HBD Edited by herebedragons, : No reason given.Whoever calls me ignorant shares my own opinion. Sorrowfully and tacitly I recognize my ignorance, when I consider how much I lack of what my mind in its craving for knowledge is sighing for... I console myself with the consideration that this belongs to our common nature. - Francesco Petrarca "Nothing is easier than to persuade people who want to be persuaded and already believe." - another Petrarca gem. Ignorance is a most formidable opponent rivaled only by arrogance; but when the two join forces, one is all but invincible.
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herebedragons Member (Idle past 886 days) Posts: 1517 From: Michigan Joined: |
I will call what I see as your scenario the Faith Speciation Hypothesis or FSH. Whether we are talking about actual new species or just varieties, breeds or whatever, we need to go from one original species and eventually have multiple modern species, varieties or breeds whatever terminology you wish to use. However, if your claim is that your scenario only leads to new breeds and not new species (or what we recognize as species) then it is really quite meaningless as an explanation for the diversity of species.
I will refer to Recombinant Inbred Lines as RILs. ---- 1. In the FSH scenario, there was originally a single, presumably highly heterogeneous breeding pair (from the ark). The RIL scenario also starts with a single, highly heterogeneous breeding pair. In both cases, it is presumed that the parents were chosen because of particular traits. In FSH, it would be traits that would allow survival in the post flood world. The RIL parents are chosen because of some trait of interest, such as disease resistance, high yield, etc. Typically, one parent has the trait, the other does not. It can also be a combination of traits. ---- 2. In the FSH scenario, this single breeding pair must reproduce until a suitable sized population forms to allow a daughter population to split off. During this initial period, the population will quickly lose heterogeneity until the population is large enough to begin random mating. This will also have the effect of distributing the original alleles throughout the population so that selecting unique combinations of alleles will become less and less likely. In other words, the population, as a whole, will become more homogeneous. The larger this initial population becomes, the less likely it is that a daughter population will have a unique mix of alleles. In the RIL scenario, progeny of the original pair are selected immediately and not allowed to interbreed. This keeps the population heterogeneous. Each progeny of the first cross will have a unique mix of genes, no two will have the same combination. The F1 population will be highly heterogeneous both at the individual genotype level and on the level of the population as a whole. The selection process in the RIL scenario ensures that every line will have a unique set of genes and alleles and that each line will be different than the parents. The FSH does not; daughter populations could be representative of the parent population and result in an identical or very similar population. ---- 3. FSH: Daughter populations are chosen at random for a specific environment. The combination of alleles they have may or may not be suitable for that environment. Thus, in this scenario, it may take several daughter populations before a suitable match of genotype to environment is found. The problem is, that daughter populations in this scenario are fairly limited. RIL: Daughter populations consist of a single individual or breeding pair and are also selected at random. The environment is constant between daughter populations, but there are relatively unlimited numbers of daughter populations, limited only by the number of offspring per generation. How long would it take to produce 10 daughter populations in the FSH scenario compared to the RIL scenario? Also, you should not object to the environment not being different in the RIL scenario, since you dismiss natural selection as a mechanism of change and have stated that it is only necessary that allele frequencies change. ---- 4. FSH: daughter populations are isolated from the original population and from each other. RILs: daughter populations (individuals or pairs) are isolated from the original parents and from each other. ---- 5. FSH: inbreeding within the daughter population causes increased homogeneity and the small population size causes increased rate of drift which increases the odds that alleles at low frequency are lost and alleles with high frequency are fixed. Homogeneity is limited as eventually the population will grow large enough to begin random mating. RILs: inbreeding causes homogeneity to increase rapidly since every generation operates at maximum inbreeding rate. Fixation and allele loss happen at the maximum rate possible. No possible scenario in the wild could generate homozygous populations faster than selfing or sibling mating. Any randomness to the mating, meaning the less related a breeding pair is, the longer it will take to fixation and homogeneity. I could show you how this works mathematically, but I don't suppose you would be too enamored by my efforts. ---- 6. FSH relies on random selection of initial population, moderate levels of inbreeding, and changing allele frequencies to bring about a new form or species. End result is populations of moderately homogeneous individuals with a new set of allele frequencies compared to the parent population. RIL relies on random selection of initial breeding pair (or individual), maximum levels of inbreeding, and rapid fixation of alleles and changing allele frequencies. End result is a highly homogeneous population with a new set of allele frequencies compared to the parent population. --- How are these methods different and why does the FSH scenario supposedly result in the formation of a new species (breed, variety or whatever) and RILs do not? To be fair, RILs do result in unique traits. But no one would want a population based on a RIL. The RIL population is used to identify key gene regions associated with a desirable trait. Once this region is identified, a RIL may be back-crossed into a more suitable genetic background. For example, a RIL may have a desirable level of disease resistance but have really poor yields. This could be crossed into a variety that has poor disease resistance but very good yield. You would then screen the progeny of the back-cross for those desirable qualities and hopefully, the region that confers disease resistance is incorporated into the variety that has good yield without disrupting the desirable qualities of that variety. RIL populations guarantee the outcome you predict of small, inbreeding daughter populations. It happens in just a few generations, at a much faster rate than could ever happen in a wild population. It is the founder effect on steroids. Changing allele frequencies due to isolation and homogenization is not sufficient to create new species. If it were, it would be happening all the time. HBDWhoever calls me ignorant shares my own opinion. Sorrowfully and tacitly I recognize my ignorance, when I consider how much I lack of what my mind in its craving for knowledge is sighing for... I console myself with the consideration that this belongs to our common nature. - Francesco Petrarca "Nothing is easier than to persuade people who want to be persuaded and already believe." - another Petrarca gem. Ignorance is a most formidable opponent rivaled only by arrogance; but when the two join forces, one is all but invincible.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
Huge SIGH. I don't get what's going on with the RIL scenario much better than I did before.
I also don't know what exactly you are trying to say about my scenario. You seem to be saying at some points that it won't produce distinctive enough new populations? Blue wildebeests aren't distinctive enough from black wildebeests? All the species in ring species aren't distinctive enough from each other? All the different kinds of cattle brought about only by random selection of limited numbers of individuals from the original wild population aren't distinctive enough from each other or from the original population? All the different kinds of cats that came from the pair on the ark aren't sufficiently distinctive? Maybe I'm not getting what you are saying. That wouldn't be surprising. But if I have trouble following a post I'm not too likely to spend the time trying to figure it out. I'm not saying I won't, I'm just saying it's hard to follow and that's discouraging. I don't recognize my own scenario in it and I'm not much clearer about yours. Take this as a first reaction; there may or may not be more to follow soon. Edited by Faith, : No reason given.
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herebedragons Member (Idle past 886 days) Posts: 1517 From: Michigan Joined: |
I also don't know what exactly you are trying to say about my scenario. You seem to be saying at some points that it won't produce distinctive enough new populations? The populations that result from that type of scenario may be distinctive and may have characteristics that distinguish them from each other, but that's not enough. It cannot go far enough to create separate species. They will just be different forms of the same species.
Blue wildebeests aren't distinctive enough from black wildebeests? All the species in ring species aren't distinctive enough from each other? All the different kinds of cattle brought about only by random selection of limited numbers of individuals from the original wild population aren't distinctive enough from each other or from the original population? All the different kinds of cats that came from the pair on the ark aren't sufficiently distinctive? Of course they are. But they don't become distinctive, separate species by simply changing allele frequencies. It doesn't work that way. So if what your scenario is trying to explain is how to make new varieties of the same species, big woop. There's not much controversy there. But the more important problem is to explain the origin of new species, and simply changing allele frequencies doesn't work for that. HBDWhoever calls me ignorant shares my own opinion. Sorrowfully and tacitly I recognize my ignorance, when I consider how much I lack of what my mind in its craving for knowledge is sighing for... I console myself with the consideration that this belongs to our common nature. - Francesco Petrarca "Nothing is easier than to persuade people who want to be persuaded and already believe." - another Petrarca gem. Ignorance is a most formidable opponent rivaled only by arrogance; but when the two join forces, one is all but invincible.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
2. In the FSH scenario, this single breeding pair must reproduce until a suitable sized population forms to allow a daughter population to split off. Yes.
During this initial period, the population will quickly lose heterogeneity until the population is large enough to begin random mating. Eh? I would expect the initial phase to produce a huge variety of different phenotypes by the third or fourth generation, that would become more homogeneous as the population continues to breed. Wouldn't you have random mating with just a dozen individuals? The population could get quite large before homogeneity is reached, and daughter populations could split off at any point.
This will also have the effect of distributing the original alleles throughout the population so that selecting unique combinations of alleles will become less and less likely. If the population grows to that point before splitting off new ones, that seems logical. But I think of the gigantic population of wildebeests or what must have been the original gigantic size of populations of wild cattle before they were domesticated as small populations captured by farmers. Plenty of unique combinations of alleles are clearly available in such populations upon selection.
In other words, the population, as a whole, will become more homogeneous. Phenotypically this should be the case if it persists a long time, but I don't think that implies the sameness of genetic material you think it does.
The larger this initial population becomes, the less likely it is that a daughter population will have a unique mix of alleles. It doesn't work that way in reality though. If you can get a whole new population of blue wildebeests from a limited number of black wildebeests there's something else going on genetically than what you are ijmagining. If there is sufficient genetic diversity left in the population that formed on Pod Mrcaru from the ten original founders, despite the fact that the are quite homogeneous now, if you took ten of them and isolated them somewhere else I have no doubt that you'd get yet another whole new population of lizards. After all the original population was of course quite homogeneous and yet the brand new Pod Mrcaru lizard was the result over thirty some odd yars. I'm not sure how to spell this out genetically, it just seems to be the case. So for instance take the salamander ring species in California. Each new species has a new set of colors and markings on its hide. Each population would have had time to inbreed and grow its numbers a great deal before a new daughter population formed, but each daughter population that splits off from such a numerous former population has entirely new colors and markings from all the others that get homogenized with inbreeding over some number of generations while it is growing. It is apparently a fact. How do you explain it? My guess is that there is still a lot of heterozygosity in each population. Edited by Faith, : No reason given. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
Of course they are. But they don't become distinctive, separate species by simply changing allele frequencies. It doesn't work that way. Sure it does.
So if what your scenario is trying to explain is how to make new varieties of the same species, big woop. There's not much controversy there. p Except I'm claiming that is all there is, there is no such thing as macroevolution, and what is called speciation is nothing but the formation of a population of a given species that develops the inability to interbreed with other populations, over some generations of inbreeding in most cases I woujld suppose.
But the more important problem is to explain the origin of new species, and simply changing allele frequencies doesn't work for that If by new species you are using the usual definition of inability to interbreed with former populations I don't see why not, and in particular I don't see how mutations would make the difference which I suppose is what you are implying. All that has to happen is the increase in homozygosity at many loci and that can happen with or without mutations. How would mutations bring about a genetic mismatch any more predictably than the scenario I have in mind? Theoretically interbreeding should still be possible but something happens that prevents it. I don't think I completely understand this but I don't see that you do either. Edited by Faith, : No reason given. Edited by Faith, : No reason given.
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herebedragons Member (Idle past 886 days) Posts: 1517 From: Michigan Joined: |
It doesn't work that way.
Sure it does. I just spent several long posts describing a situation that establishes beyond a reasonable doubt that inbreeding and changing allele frequencies doesn't generate new species. Because you can't take the time and energy to understand it doesn't change my argument.
what is called speciation is nothing but the formation of a population of a given species that develops the inability to interbreed with other populations, over some generations of inbreeding in most cases I woujld suppose. Why doesn't it happen in RIL populations where the inbreeding is as intense as possible. No natural population experiences the extent of inbreeding that a RIL population experiences.
All that has to happen is the increase in homozygosity at many loci and that can happen with or without mutations. If that were true, then it should be happening in RIL populations... and it doesn't. We don't get new species forming even in hyper-increase-in-homozygosity situations.
Theoretically interbreeding should still be possible but something happens that prevents it. I don't think I completely understand this but I don't see that you do either. You "see that I don't understand it" because I am pointing out that your hypothesis is wrong? "Something" happens based on changing allele frequencies? Based on homogeneity? What could that be? What changes in a homozygous population prevents it from interbreeding with the parent population? I could make 1,000 RIL lines from a single parental pair and inbreed them until they were 99.9% homozygous and I guarantee that everyone of those 1,000 lines would still back cross with both of the parental lines. How could that be if you are right and all it takes to generate genetic incompatibility is inbreeding and changing allele frequencies? ABE: It is possible that a mutation in a few of the lines would prevent crossing, but that would be rare. So... how did FSH produce: horses with 64 chromosomes and donkeys with 62 chromosomes (inter-fertile -same "kind") ----... and in the fox "kind": Red fox = 34 chromosomesTibetan fox = 36 chromosomes Kit fox = 50 chromosomes Bengal fox = 60 chromosomes ----... and in the mouse "kind" Mouse = 40 chromosomesRat = 42 chromosomes ?? It doesn't work that way. HBD Edited by herebedragons, : No reason given.Whoever calls me ignorant shares my own opinion. Sorrowfully and tacitly I recognize my ignorance, when I consider how much I lack of what my mind in its craving for knowledge is sighing for... I console myself with the consideration that this belongs to our common nature. - Francesco Petrarca "Nothing is easier than to persuade people who want to be persuaded and already believe." - another Petrarca gem. Ignorance is a most formidable opponent rivaled only by arrogance; but when the two join forces, one is all but invincible.
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herebedragons Member (Idle past 886 days) Posts: 1517 From: Michigan Joined: |
Wouldn't you have random mating with just a dozen individuals? Here's the question you need to ask... How closely related are those 12 individuals? Say they are all siblings, ie. they come from the same parent. That would not be random mating, regardless of who mated with who, that would be inbreeding - a form of non-random mating. Inbreeding occurs when individuals are more likely to mate with close relatives, or in genetic terms, are more likely to unite gametes that are identical by descent, ie. inherited from the same parent. The result is a tendency towards homozygosity. So you could have random mating in a population of 12 individuals, but they would have all had to come from different parents.
It is apparently a fact. How do you explain it? Sometimes, yes, changes in allele frequency is sufficient to explain differences in morphology. But in general, it's just not enough. Something else is needed to produce new species, especially those that are genetically incompatible with the parent population. HBD Edited by herebedragons, : clarity in last paragraphWhoever calls me ignorant shares my own opinion. Sorrowfully and tacitly I recognize my ignorance, when I consider how much I lack of what my mind in its craving for knowledge is sighing for... I console myself with the consideration that this belongs to our common nature. - Francesco Petrarca "Nothing is easier than to persuade people who want to be persuaded and already believe." - another Petrarca gem. Ignorance is a most formidable opponent rivaled only by arrogance; but when the two join forces, one is all but invincible.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
I have been using the term inbreeding simply to describe breeding within the reproductivelyt isolated population, which is probably but not absolutely necessarily made up of nonrelated founding individuals. Should I be using a different term?
changes in allele frequency is sufficient to explain differences in morphology. But in general, it's just not enough. Seems to me it is.
Something else is needed to produce new species, especially those that are genetically incompatible with the parent population. Mutations I suppose? But as I've already said, why should mutations be genetically incompatible? If they are "beneficial" they replace an existing allele with a functioning allele, meaning it fits just fine in the gene and codes for a protein that codes for a phenotype. Where's the incompatibility?
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
Since you are insisting that I grapple with your example I'll try tomorrow. My guess is it doesn't prove anything like what you think it proves and has nothing in common with my scenarios.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
You know what? I'm not going to work on it more. You can't just come along and use an example from an entirely different science and claim it disproves my argument. If your example could be done with animals that could be fair, and if it can then that's what you need to do. Plants no, they are too different. If your claim is true it ought to be true for my kind of example so that's what you need to prove.
Edited by Faith, : No reason given.
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Percy Member Posts: 22504 From: New Hampshire Joined: Member Rating: 4.9 |
Faith writes: I totally absolutely disagree. All it takes in some species to come to a point where interbreeding is impossible is the loss of genetic diversity through selection over a number of daughter populations. ABE: This would be the same genetic situation as the cheetah's and the cheetah cannot interbreed with other cats. That's because cheetahs and other cats are different species. As cheetahs lose habitat to human expansion their numbers are dropping along with their genetic diversity. This loss of genetic diversity is not causing any speciation - in fact, the uniformity of cheetahs is notable.
Nonsense. For one thing mutations are only variations on existing alleles and if new gene frequencies of those existing alleles aren't enough to lead to genetic incompatibility, there's no reason to think a functioning allele brought about by mutation would behave differently. Of course a mutated allele can behave differently from the original. An allele is a template for a protein. When an allele changes then the protein may change, and when the protein changes it affects the organism.
A mutation is NOT microevolution, it's a single change in a single allele, utterly lost in a population unless selected. A mutation that is not passed on to the next generation is certainly lost, but there is nothing to prevent its being passed on unless it negatively affects the organism's ability to reproduce. And a mutation is most certainly microevolution because it affects the gene frequency in the population. The original allele's frequency is less because a new allele now exists.
EVOLUTION REQUIRES SELECTION, requires the proliferation of that mutation at the very least, and OF COURSE speciation isn't going to happen from one mutation. If an organism reproduces then obviously it was selected. Having a mutation is not a sterilizing event. Humans average around 100 mutations each, and the vast majority of us are not sterile. And of course speciation isn't going to happen from a single mutation. That's why it's microevolution.
Speciation isn't what I'm focused on but it could happen from extreme reduction of genetic diversity in a whole population with new gene frequencies of alleles whether mutated alleles or not. And yet, as I said before, breeders are unable to produce new species.
Macroevolution is the accumulation over time of many mutations sufficient to produce new species. Oh blithering nonsense. This does not happen. Except that it does. There is nothing that could stop the occurrence of mutations with every reproductive event.
Even if you got all new phenotypes you'd still have the problem of loss of GENETIC diversity due to SELECTION, which is necessary to the formation of new species. Mere loss of genetic diversity does not create new species. Again, that's why breeders cannot produce new species. Just using selection to remove alleles from a subpopulation leaves the breeder with the same species, albeit a population with characteristics he emphasized. It takes time for the accumulation of sufficient mutations to form a new species.
Selection is necessary to evolution... Nobody said it wasn't. That you keep thinking nobody grasps this indicates some gaping hole in your understanding of what people are saying.
...and when you have selection you have the replacement of some alleles by the new set of high frequency alleles,... That's only one of the possibilities. Selection can result in alleles at any frequency level.
always always always the necessary reduction in genetic diversity brought about by selection/evolution. Speciation by mere reduction in genetic diversity never happens.
I was asking for a picture of what people have in mind when they keep saying mutations can overcome the necessary loss of genetic diversity brought about by selection. All it takes is for the rate of acceptable mutations to exceed the rate of loss of alleles. --Percy Edited by Percy, : No reason given.
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