punctuated equilibrium

[jj]

Every organism has a range in which conditions favor its survival, and populations tend to become stable within that range. The type of 'sweep' of a gene pool you suggest depends not only on a mutation producing a significant advantage, but also on it producing a relatively drastic change -- this is highly disfavored probabilistically.


No, all it has to do is have a major superiority in reproduction. "Major" in this light doesn't have to be much, either, and when one plant can suddenly grow higher and get 3x the energy while shading out the other at the same time, we're not talking about a 1% advantage, either, we're talking about rapid extinction events where a previous plant's niches vanish "overnight" in terms of genetics.

We have at least, it would appear, two examples of that, one where plants developed upright rigid stems, and another when those stems became vascularized. I'm sorry, the cites are well evaporated from my memory, one was a SciAm article, the other one came from a text that it referred to.



As you approach the outer edges of an organism's range, conditions generally become less favorable, until you reach a point at which any individuals able to survive at all are unlikely to reproduce successfully.

Irrelevant, we're not talking about reaching the outer edges of an organism's range in the environmental sense, really, we're talking about its niche being eliminated.

Even if some mutation occured which would better equip offspring for survival at the edge of the range (or even beyond), that mutation would (by definition) make the offspring less suited to life nearer the middle of the range, so it can't take hold unless a sub-population becomes reproductively isolated from the main population.

Again, irrelevant. We're talking about a major structural change here, not a minor shift of viability.

I didn't say that they happen very often, but the evidence seems to be there that they did happen, and that when such a new structure appears, that it spreads rapidly.

Evolving independently of the main population, such a daughter population might then chance on something that would be a significant advantage back in the home range.

Look, I'm not sure what you're arguing about. Isolated popluations can also cause major shifts. The two aren't mutually exclusive.

Another way of looking at it is that the main population had reached an adaptive peak, but it wasn't the highest one around. Reaching the higher peak meant backing up so as to permit passage through a fitness valley, but backing up is an evolutionary no-no.

Why might there be any need to "back up". Let's take stems. We have a non-vascular plant in which some cells have adapted to make stems 1" long. This puts the leaf (or equivilent) up above the rest of the stuff. This is a BIG energy advantage, not a little one. This continues, until the stem is long enough that there is a transport bottleneck from base to top.

That's step 1. No 'backup' involved, and the first 1" is a major breakthough in the plant's viability.

Step 2 comes later, when the stem cells (meaning plant stem here) start to die because there is no penality to that, except for the surface cells with access to gasses. Pits form in the cells, one day they line up in a plant, and we have suddenly relief from the transport bottleneck is resolved. Again, no backing up, and no real visible change (visible ::= fossil) until vascularization starts to work. Suddenly the stems can be much longer, the plant starts to shade out the stuff below it, AND the stuff with non-vascular stems. Suddenly, it sweeps the gene pool because it shades out the competition.

This isn't just supposition...

It doesn't require any kind of "regression".

There appears to be fossil evidence, such as can exist.

Does that deny that isolated populations could reintroduce vigor or new traits? No. The two aren't mutually exclusive.

The sub-population, though, started in a fitness valley (being under-adapted to their environment, which was outside the ancestoral range) and climbed a different peak (which turned out to be higher).

A lot of the debate around PE seems to have centered on whether it is anything all that exciting a new; such allopatric speciation is easily handled by mainstream Darwinism.

Please don't call your view "mainstream Darwinism". The two ideas are not mutually exclusive and both come substantially from after Darwin wrote Origins...

 

[jj]

Which interesting examples do you have in mind? Or better yet, an uninteresting example.

I.E. Bulls*it!

Once again, we have simple denial of obvious evidence, it appears.

Hammegk, do you have anything constructive to say, or is your entire psyche geared solely to denial of everything anyone else has to say? Have you an opinion and an position, or do you just live to attack others'?

 

[hgc]

Once again, we have simple denial of obvious evidence, it appears.

Hammegk, do you have anything constructive to say, or is your entire psyche geared solely to denial of everything anyone else has to say? Have you an opinion and an position, or do you just live to attack others'?

Don't blame hammy. His magic *I* is defective and tuned into a different reality.

 

[Dymanic]

Originally posted by jj

No, all it has to do is have a major superiority in reproduction. "Major" in this light doesn't have to be much, either...

The PE model is an explanation not for imperceptible changes, but for the sudden, significant changes that appear in the fossil record. I agree that small changes are what we would expect as a population moved toward an adaptive peak. (though such small changes would likely be individually invisible in the fossil record). Once a population has reached stability at that peak, there is very little room for any further small changes to work; at that point, only a significant change will get any leverage.

Irrelevant, we're not talking about reaching the outer edges of an organism's range in the environmental sense, really, we're talking about its niche being eliminated.

Niles Eldrige, co-author of the PE model, thought it relevant enough to include in his book. It seems to me that any change worthy of the designation 'significant' would require an equally worthy explanation, and allopatric speciation seems more worthy to me than 'hopeful monsters' (I know, I know, that's not what you're saying -- but you are pointing in that general direction). I don't quite follow what you are saying about the niche being eliminated -- how is the niche eliminated? Aren't we talking about a niche being overrun?

Please don't call your view "mainstream Darwinism".

Please don't make assumptions about what I call 'my view'. I'm not particularly interested in all the haggling over designations like 'neo-Darwinism', 'ultra-Darwinism', etc.

 

[hammegk]

I note that 2 fu*kheads responded -- with no answer to my question.

Darwin, are you up to answering my challenge, or would you also blather & pule?

No, a plant just like another (except gene coded for a longer stem) does not prove the Theory of Evolution.

 

[BillHoyt]

No, a plant just like another (except gene coded for a longer stem) does not prove the Theory of Evolution.

Hammy,

Speciation is speciation, and is very good evidence supporting evolutionary theory. If plant species A gives rise to plant species B and B turns out to have a nearly nil gene flow with A, that is speciation.

Cheers,

 

[hammegk]

Hammy,

Speciation is speciation, and is very good evidence supporting evolutionary theory. If plant species A gives rise to plant species B and B turns out to have a nearly nil gene flow with A, that is speciation.

Cheers,

Good supporting evidence will be speciation from say, wheat, to palm trees. Queer fruit flies with legs where the eyes should be also show that gene manipulation controls structure, BFD.

Still waiting on Darwin to support his contention.

 

[UnrepentantSinner]

Good supporting evidence will be speciation from say, wheat, to palm trees. Queer fruit flies with legs where the eyes should be also show that gene manipulation controls structure, BFD.

Still waiting on Darwin to support his contention.

Oh the sense of ennui in your avatar is soooo apropos.

How about refuting the 29 Evidences presented here.

{preemtive}
Crickets
{/preemtive}

I thought so...

 

[Dancing David]

Which interesting examples do you have in mind? Or better yet, an uninteresting example.

I.E. Bulls*it!

Whats the matter Hamee, your arthritis acting out?

There are a number os species radiations in recent geologic history and some good example of evolution at work.

The radiation of the Icterid(sp?) or crows from Australia, started about 40,000 BP (before present), they have become the dominant nest predator and are a very good example of how a radiating species spread and diversifies.

There is also the recent finding that human use of anti biotics cause the natural slection of anti-biotic resistant bacteris. Hmmm, I guess that not evolution?

In bacteria is gas also been observed that they can communicate resistance between bacteris.

In insects there is definitly natural selection for pesticide resisitant insects.

The radiation of species is occuring as a result of the human impact on the North American continent, coyotes being the most notable.

I am very interested in why you don't participate in these discussion Hamme? You seem to have adopted a stance similar to Billiefans, you could behave more intelloigently, but perhaps you have nothing to contribute.

Darwin: Yes , I believe that the climatics change brought about by the Antartic movement contributed to the decline of the dinosaurs, with the cometary impact adding the final blow.

 

[hammegk]

How about refuting the 29 Evidences presented here.

Yup, 29 ways to support an hypothesis -- as is clearly noted. If you feel the existing Darwinian based hypotheses (note plural) is an only and complete answer, good for you. I remain a skeptic. Even more laughable is the distancing of all evolutionary "scientists" from the real, key, question: How does Life result from non-life. I certainly agree that dna can be manipulated; is dna "non-life" in your thoughts? If so, why?

Dear Dancing: If a bacterial resistance developing to an antibiotic -- or transposon transfer to another bacteria -- is a macro event for you, so be it. I restate, bulls*it.

 

[hgc]

Yup, 29 ways to support an hypothesis -- as is clearly noted. If you feel the existing Darwinian based hypotheses (note plural) is an only and complete answer, good for you. I remain a skeptic. Even more laughable is the distancing of all evolutionary "scientists" from the real, key, question: How does Life result from non-life. I certainly agree that dna can be manipulated; is dna "non-life" in your thoughts? If so, why?

Dear Dancing: If a bacterial resistance developing to an antibiotic -- or transposon transfer to another bacteria -- is a macro event for you, so be it. I restate, bulls*it.

This is more like the muscleman style of debate -- Nothing you have said has passed my ears, ergo my point is proven!

 

[Dymanic]

Oh, pardon me, I seem to be lost. Is this the abiogenesis thread? I was looking for the punctuated equilibrium thread.

 

[Dancing David]

Dear Dancing: If a bacterial resistance developing to an antibiotic -- or transposon transfer to another bacteria -- is a macro event for you, so be it. I restate, bulls*it.

How so Hamme, to state it is bull poop is great but how is that so? We have billions of bacteria in an infection, millions are selected for anti biotic resistance, and eventually you have anti-biotic resistant bacteris.


Insecta re in the millions in a field sprayed with insecticide and then survive in the thousand, and eventualy you have pseticide resistant insects.

These are traist that are selected for in natural selection.

Or in your vauge response are you stating that you would like to see the evolution of morphology? What exactly are you trying to say?

So these are small ctitter I grant you, but there is MACRO in the sense that it happemns on a very large scale.

So where is the intellectual brilliance, I know you have a point, are you so unsure that you won't state it?

 

[Dragon]

Which interesting examples do you have in mind? Or better yet, an uninteresting example.

I.E. Bulls*it!

One interesting example - HIV.

 

[Darwin]

"Darwin: Yes , I believe that the climatics change brought about by the Antartic movement contributed to the decline of the dinosaurs, with the cometary impact adding the final blow."

OK.I still am not sure about your position.
Let´s say that climate change has been offered before.I have no doubt that the climate change contributed to the extinction but how and which form it was brought,is debatable (Asteroid would have caused cooling to a great degree).
However,the climate during cretaceous was not all that harsh (all the way to late),not a hothouse but fairly warm (enough) for dinosaurs to stand.We have evidence of glaciation around Antarctic by those times,and interestingly enough,certain groups of dinosaurs (like hypsilophodonts) seem to have done fairly well down there.
Just some points of mine.


hammegk,
Examples of evolution,big or small,have been handed out to you.
Some sites; (some examples)
http://www.pbs.org/wgbh/evolution/library/10/3/l_103_02.html
http://www.holysmoke.org/cretins/speci.htm
http://www.pbs.org/wgbh/evolution/library/01/2/l_012_02.html

 

[jj]

The PE model is an explanation not for imperceptible changes, but for the sudden, significant changes that appear in the fossil record. I agree that small changes are what we would expect as a population moved toward an adaptive peak. (though such small changes would likely be individually invisible in the fossil record). Once a population has reached stability at that peak, there is very little room for any further small changes to work; at that point, only a significant change will get any leverage.

Stop thinking of this as a linear system, it's not.

A small change, say some pits in the cells in a stem, can change a stem from mere support to vascularized, and create a gigantic advantage for that organism and any that get its genes.

You can be at an inflection point, be fully optimized for that point, niche, etc, but something SMALL can majorly change the rules, resulting in reshaping of the "peak" so that it's not a peak any more, in fact it could be a minimum in the new regime.


Please don't make assumptions about what I call 'my view'. I'm not particularly interested in all the haggling over designations like 'neo-Darwinism', 'ultra-Darwinism', etc.

Small changes can give no advantage (usual), some disadvantage (also usual), and sometimes a huge advantage, perhaps due to something that would seem quite unrelated...

This doesn't mean that gradual evolution doesn't happen, of course, we've observed it in the lab, it does.

But it does mean that once in a great while, some simple thing comes along, happens in the right place, and changes the rules, and then we see "sudden" changes. Since "sudden" means 100,000 years in the fossil record, we have to realize that there is lots of time for some new change to spread and still be "sudden".

Again, the boundary where both stemmed plants and vascularized plants appear would seem to be just an example of such a thing. Stems weren't worth a lot without vascularization, but they were worth something. Then vascularization hit and spread like a weed (literally, I expect) changing the landscape in a geologic instant.

 

[hgc]

...

hammegk,
Examples of evolution,big or small,have been handed out to you.
Some sites; (some examples)
http://www.pbs.org/wgbh/evolution/library/10/3/l_103_02.html
http://www.holysmoke.org/cretins/speci.htm
http://www.pbs.org/wgbh/evolution/library/01/2/l_012_02.html

Any of those have wheat morphing into a palm tree? Afterall, there's no defense against reality like an insurmountable barrier of obstinance.

 

[CapelDodger]

from hammegk:

How does Life result from non-life

There's an interesting report in Science 15th August 2003 p938, "A Possible Primordial Peptide Cycle" by Claudia Huber et al. It describes a metabolic process which occurs in hot aqueous conditions in the presence of CO and (FeNi)S particles - conditions which can be found around oceanic volcanic vents. This is not life as we know it but indicates a possible route for non-life to become life. Peptides are both extended and dismantled in the same conditions, the energy deriving from oxidation of CO to CO2. This allows a rapid "sampling" of many different peptides and proteins which could form feedback loops leading, eventually, to simple cellular life.

The search for the origins of life have a long way to go, but a start has been made.

 

[Darwin]

"Any of those have wheat morphing into a palm tree? Afterall, there's no defense against reality like an insurmountable barrier of obstinance."

Might not have to do with what the theory predicts.

 

[hgc]

....

The search for the origins of life have a long way to go, but a start has been made.

For most, it begins and ends in Sunday school.