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Author | Topic: How different is macro/micro evolution | |||||||||||||||||||||||
kuresu Member (Idle past 2513 days) Posts: 2544 From: boulder, colorado Joined: |
leave it my total lack of experience compared to yours.
I gave my understanding of what you meant by different levels of selection as sort of a half joke. I didn't intend for it to carry on further. oh well. let's see if this is better you brought up different selection levels to show how macro/micro are different in more than just time span? if I'm wrong again, tell me, and I won't try any further interpretations. if I'm right, no need to go further, I think. yeah . . . . . All a man's knowledge comes from his experiences
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RAZD Member (Idle past 1405 days) Posts: 20714 From: the other end of the sidewalk Joined: |
I used to argue (as several have here) that it is the same mechanism, that there is no difference, no barrier to macro evolution that is not broken by micro evolution -- and this is still true, but
that is because micro drives macro but there are also different mechanisms at work, and this is where I've modified my opinion. If we look within a species population what we see as the mechanisms for evolution are (1) mutations and (2) natural selection. These are continually going on within all species, but within natural selection are some mechanisms that provide a trendency towards stasis, an averaging back of the population towards an median organism and deselection of extreme types, usually conveyed by sexual selection and by gene mixing -- the mutations that are not lethal or debilitating are shared around and spread from generation to generation. Once speciation has occurred however the population is divided, the gene mixing is cut off, and this allows for (but doesn't require) more rapid divergence from the old center. You can think of micro as all those selection mechanisms acting within a population, and macro as all those selection mechanisms acting between populations. Enjoy. we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist
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Brad McFall Member (Idle past 5032 days) Posts: 3428 From: Ithaca,NY, USA Joined: |
Yes, this is pretty much it.
You can read what Razd wrote bout the "difference." I think there is probably much more to it. If one is walking rather than reading a clock (as in the OP) one crosses geography even if one is walking along a geodesic say. As Subbie mentioned, I think this is quite accurate, the notion of kind fits into this discussion as well, if "the kind" was defined and deliminted better than the confusion over any difference of macro and micro is. I used to term this "meso" evolution on EVC. The word is from Dobshanksy and used by Lerner. The mods however had placed this topic under Biological Evolution so I suppose that we are to talk focusedly only on how different evolution through longer times may or (may not) be different in biological aspects. There may be an error of plausible contingency in Gould's view to extend the range of the evolutionary individual but it would require that logic restrict the notion of form from its current plurvocal instantiation into one with mulitple connotations. This can more easily be concieved from a creationist perspective where mechanism is reflectively subordinated to design but in the empirical secularlization of academia noticing how a "KIND" through geogography can result IN A LINE denoted is demoted because there would be some determinative consult and there does not appear to me to be any funds or foundation needed to support proximately empirical studies that seperate internal and external purposiveness (as in Kant's trascendentalism). The needed applications would be with the relation of the geometric manifestation and mathematical meaning of a line of points where D'archy tompson wrote of transformed co-ordinates. Without the kind this might be approached without transfinite numbers but if one wanted the broadest method the final ingredient for success probably comes when all of this base work is combined with Croizat's geography to cross the globe and trot out a framework larger than can be found coming into secular institutions because they refuse to grant the design until after it has already been printed. As to biological issues only the subtility here really has to do with "translating" the feeling of an easier go of life with siblings than with random individuals IN THE SAME LIFE and to apply this to creatures we have no real cognition in common with but can observe. If you take the trace with Dakwins and his purplest prose you will end with a foreign car and not the vehichle that rusts rather than rots when it remains for the scavengers.
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ohnhai Member (Idle past 5162 days) Posts: 649 From: Melbourne, Australia Joined: |
There is no difference.
You might as well claim that a millennium is an impossibility as no one person has ever witnessed one in its entirety. Sure days happen, we see that all the time. But there is no difference between a day and a millennium. They are both arrived at by incrementally adding a second a go, till you get to the destination. Tic . one secondTic . one second. Tic . one second Tic . one second. Tic . one second Tic . one second. Each tic, a minuscule change that has little or no impact on the whole. But given enough of them, over a suitable period and you will get an hour, a day, a year, a decade, a century, a millennium. Huge changes through insignificant steps. Evolution is the same. Micro and Macro are simply the Days and Millennia of biological change, one witnessed easily the other not so. They are simply names for different numbers of the same event. Essentially different units for the same measurement. FYI:1 minute = 60 seconds 1 day = 86 400 seconds 1 millenium = 3.1556926 10^10 seconds Edited by ohnhai, : added the ^ SYMBOL
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subbie Member (Idle past 1254 days) Posts: 3509 Joined: |
but there are also different mechanisms at work, and this is where I've modified my opinion. As I understand what you've said, the only difference in mechanisms is that the "tendency towards stasis" no longer operates once a population has divided. In other words, there are no additional or different mechanisms that operate at the "macro" evolutionary level, but simply one mechanism that is no longer operative. Is my understanding accurate? Those who would sacrifice an essential liberty for a temporary security will lose both, and deserve neither. -- Benjamin Franklin
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Brad McFall Member (Idle past 5032 days) Posts: 3428 From: Ithaca,NY, USA Joined: |
source
If the sorting or shuffling was selective of The Boltzmann equation is revelatory in uniting the macrothermodynamics of classic Clausian entropy with what has been described above as the behavior of a system of microparticles occupying energetic microstates.
rather than a selection of "cards" signing the evolutionary individual, then there might even be a larger realm than Razd considered objective but would fall in his prior non-changed position and Gould was correct about non-end to end stacking in geological time. I am not sure Gould is dead on here where if he had said, "the synthesis is effectively dead." This is what I meant by "slowing down." It is not clear to me that Razd's post avoids the point in the paragraph below:
Edited by Brad McFall, : added justification
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Hyroglyphx Inactive Member |
There is a general assumption that the entire theory of evolution was never discussed prior to Linnaeus, Lamarck, Wallace and Darwin. This is a common misconeption. The concept of evolution, particularly, what we call micro and macroevolution, was a topic of debate in ancient Greece. Among the most notable were the famous philosophers, Pythagoras and Aristotle -- Pythagoras arguing in favor of evolution, Aristotle ultimately rejecting the notion.
My reason for mentioning has to do with well-known observations and speculative theories. The plain fact about it is that we know beyond all reasonable doubt that DNA has a terrific capacity for diversity. And even prior to Crick and Watson's contribution to DNA research, we always knew that some mechanism was responsible for this, we were simply unable to define it prior. What hasn't been witnessed, ever, is what Mayr referred to as, "transpecific evolution," which later synthesized into macroevolution. Darwin's contribution and his extrapolation off the works of his grandfather, Erasmus Darwin, obviously gave the theory its most compelling reasons to believe in the theoretical basis for such an evolvement. Darwin argued that certainly within his lifetime, he would able to identify the innumerable transitional forms in the fossil record. During his time, he recognized that it was seriously lacking and that all fossilized creatures seemed to appear abruptly in full formation just as we see them today. Over 100 years later the theory was still built around circumstancial evidence. The theory, seriously anemic with lacking physical evidence, the eminent Gould and Mayr expounded on an older theory to which they would refer to as Punctuated Equilibrium or Equilibria. As far as I can tell, it was a total abandonment of Darwin's bread and butter, which is slight gradations building upon on each other. Instead, Gould and Mayr argued that little to no evidence should be found because the large population would experience long ages of stasis, where smaller, peripheral populations would branch off creating speciation. This seems like a clever way to absolve the theory of any wrong conclusions and to keep it afloat by presenting no evidence to support a lack of evidence. What's particularly disturbing, creationists have always pointed this out, yet we were expected to believe the whole of Darwinism. It was only when Gould and Mayr gave a tentative and passive thumbs down to Darwin's bread and butter that the rest of the biological community finally followed suit. In a sea of pure and unadulterated conjecture, I see no compelling reason to continue in this vein. The theory still faces the exact same challenges that Darwin faced, even in light of technological advances. In fact, these advances within technology only seem to undermine it, not enhance it. “It is in vain, O' man, that you seek within yourselves the cure for all your miseries. All your insight has led you to the knowledge that it is not in yourselves that you will discover the true and the good.” -Blaise Pascal
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jar Member (Idle past 394 days) Posts: 34026 From: Texas!! Joined: |
There is a general assumption that the entire theory of evolution was never discussed prior to Linnaeus, Lamarck, Wallace and Darwin. This is a common misconeption. Actually, that may be common among Biblical Creationists, but it is certainly not the case among anyone who has examined either the TOE or the history of the search for explanations for how Evolution took place. Aslan is not a Tame Lion
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Brad McFall Member (Idle past 5032 days) Posts: 3428 From: Ithaca,NY, USA Joined: |
I think this is where Mayr distances himself somewhat from Gould.
The paper just happened to be on the top of a pile for some inexplicable reason. I know it is hard to read to the right. I think this is from his Evolution: One Long Argument. I have tried to show in this thread that "big" is really bigger than gradual conceptually but might not in Gould's "gradual" discussion of PE, as a case for Macro Topics, be experiential. This would leave the creationist scholar to take apart Mayr's references to vertical and horizontal and restore an older intra-creationist wedge.
I know that ICR writings try to take macro evo back to the Greeks but I find a better foward writing if it is only taken back to Mayr's citation of the "chain of being" which he had associated with Kant.
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RAZD Member (Idle past 1405 days) Posts: 20714 From: the other end of the sidewalk Joined: |
... the only difference in mechanisms is that the "tendency towards stasis" no longer operates once a population has divided. Not exactly -- that's more of a result than a mechanism. To me it is a subtle little difference but important enough to consider. After a speciation separation, each population now has a new {stasis equilibrium} point that it will try to "center" (chose mates) around, and there is no mixing of genes between the divided populations so those {stasis equilibrium} points can diverge. But there are other population dynamics that are involved both before and after that are different. Take pelycodus: Where you see a general (normal) trend toward larger individuals as time passes, and then a speciation event with subsequest divergence between two populations. The right branch continues with the linear increase in size, however the left branch dives back to re-occupy the original {size\niche\function}. This would be forced by competition between the two groups, a selection pressure that doesn't happen while they are one population. Once they have diverged sufficiently that such competition does not threaten survival of one population, then each are free to take whatever evolutionary paths they want, but they will not be the same path - that bridge is burned. Note that the reduction in size is faster than the general increase in size. This is the effect of being de-linked. Note also that the population variation is restricted to the same general width rather than getting broader at each time level. This is the effect of the trendency towards stasis. Stasis doesn't have to be a result, btw, it can be {static relative to a continued trend} as above; it is just a tendency inherent in sexual selection (imho) towards average individuals in a population -- ie sexual selection could be a two-edged sword, allowing greater (liberal) mixing of genes along with quick (conservative) selection to omit extreme divergence. I tried to find the post where I had come to this conclusion last night and couldn't (silly ol search system + tired brain + impatience), but you can think of all the selection pressures that operate within a population and all the selection pressures that operate between populations as being the essential difference in the shape of the evolution that is observed. Wait, I finally found the post
Message 267 "micro"evolution is the individual changes in species over time (and space), each change is a separate "micro"evolutionary event. This represents short term trends and fluctuations (larger beaks or smaller beaks etc), the change that occurs before speciation takes place. "macro"evolution is the accumulation of changes over long periods of time, thus "macro"evolution is not the {change in species over time due to mutation and natural selection} but the {accumulation of changes incorporated into species by "micro"evolution ... and natural selection}. This represents long term trends - the change that continues (by continued "micro" changes) to occur once speciation has been achieved. Which is further refined in
Message 278 The more I think about it, the more it seems to me that it's more than that, it's also the difference between application at different levels: (1) the individual level -- each individual is conceived with it's basic kit of mutations and the fitness of the individual is tested to survive to live and breed, those with non-lethal mutations live, those without disabling mutations survive and grow, those without disadvantageous mutations - and maybe a bit of luck - breed. This is where continued mutation and adaptation occur. (2) the population level -- the population is made up of individuals with a wide variety of mutations, adaptations and abilities, and the dynamics of interactions of the members of the population in reaction to the environmental pressures is where change versus stasis tendencies are selected, this is where the dynamics of the different adaptations and abilities come into play, whether for survival or for breeding. It can only act on the basis of the net accumulation of mutations that are available. You could also say that "micro" changes are not fixed in the population, as the population as a whole can revert under changed selection pressures (the way the beak size can revert). Whether the {features\alleles\variations} can become part of the defining characteristics of the species is debatable, as this gets into what distinguishes one species from another (especially on a timeline). Once a speciation has occurred those changes have become part of the {defining genome} of the species and so do become fixed (as part of the previous amount of variation is discarded in the divide), albeit still subject to "micro" changes around that {center\node\nexus}. Speciation is the dividing line then between "micro" and "macro" -- and once two speciation events occur in succession the fact that "macro"evolution (by this definition) has occurred cannot be denied either: that is all that is needed to show that evolutionary branches occur and that the result is a nested hierarchy, which is the basis of all upper level taxonomy divisions. You could also use the genetic differences between the species in these subsequent speciations and of their ancestors to validate the genetic tree derivations. I would think this has been done and that there would be ongoing work on it to refine the marker systems used (anybody know of papers on this?). You can't have "macro" without "micro" -- the basic mechanism of change is still the same -- but you could have "micro" without "macro" ... hence evidence of such effect is different than evidence of (species) change over time. Hope that helps. Enjoy. Edited by RAZD, : added (species) at end we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist
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