Ask some questions about evolution here.
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06-10-2015, 10:06 PM
RE: Ask some questions about evolution here.
(06-10-2015 02:32 PM)Free Thought Wrote:  Dear Zeke;

Could you explain the altruistic paradox? And further explain how altruism has become a successful strategy despite it's evolutionarily weird nature.

It's possibly a misfiring of kin selection. Kin selection evolves the choice to favor close relatives over others, even over oneself, since it tends to replicate one's own genes.

The closer the relative, the more genes in common. This is also likely the basis of tribalism and of xenophobia.

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06-10-2015, 10:11 PM (This post was last modified: 06-10-2015 10:14 PM by Chas.)
RE: Ask some questions about evolution here.
(06-10-2015 10:04 PM)Atothetheist Wrote:  What about punctuated equilibrium? What can/ does that explain? What evidence is there for it? How does it stack up against gradualism?

(Perhaps a definition and explanation of Punct. E might be included?)

Punctuated equilibrium is not actually a real thing; or it's just evolution.

It depends on the timescale you use to view change. If you zoom in on the timescale, all change is gradual; if you zoom out, some of it looks rapid - so rapid that it looks like a sudden change.
But it's not sudden, just more rapid than when there is little change in selection pressure.

If the selection pressure stays constant, there will be little change in the genome other than random drift.

It is when selection pressure changes that we see much change, and large changes in selection pressure, though more likely to cause extinction, might cause rapid change in the genome.

But that's just the evolution algorithm.

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07-10-2015, 06:31 AM (This post was last modified: 07-10-2015 06:37 AM by TheBeardedDude.)
RE: Ask some questions about evolution here.
(06-10-2015 10:11 PM)Chas Wrote:  
(06-10-2015 10:04 PM)Atothetheist Wrote:  What about punctuated equilibrium? What can/ does that explain? What evidence is there for it? How does it stack up against gradualism?

(Perhaps a definition and explanation of Punct. E might be included?)

Punctuated equilibrium is not actually a real thing; or it's just evolution.

It depends on the timescale you use to view change. If you zoom in on the timescale, all change is gradual; if you zoom out, some of it looks rapid - so rapid that it looks like a sudden change.
But it's not sudden, just more rapid than when there is little change in selection pressure.

If the selection pressure stays constant, there will be little change in the genome other than random drift.

It is when selection pressure changes that we see much change, and large changes in selection pressure, though more likely to cause extinction, might cause rapid change in the genome.

But that's just the evolution algorithm.

No, punctuated equilibrium is different. It isn't only a matter of timescale.

Punctuated equilibrium postulates that some species (not all because some examples of evolution clearly are a better fit for gradualism) remain constant (in stasis) with respect to their morphological disparity over time (with the only variability being fluctuations about a mean with no net change) because there is no selection pressure to drive change during stasis.

For instance, we see it quite often in the fossil record (especially with invertebrates like brachiopods and trilobites and bivalves, etc) where some environments are constant for millions of years and as a result, the same species will persist with little to no morphological change over the same stretch of time.

Basically, if there is no selection pressure to drive morphological change, there won't be any morphological change.

That is the equilibrium part of it (stasis). But periods of stasis are punctuated by intervals of rapid change. This rapid change is some alteration to the selection pressures that had remained constant, that then drives either adaptation (and therefore morphological change) or extinction.


So, gradualism is essentially constant change over time (no meaningful deviation from the rate of evolutionary change) but punctuated equilibrium are periods of stasis (no net change) punctuated by rapid (short intervals of time) evolutionary change. For the first image, the horizontal lines represent no net change in the punc eq model, in reality it would be more like b in the second image where there is variability but no net change. In the second image, c (or a) would be similar to punc eq. where a change in selection pressure causes a shift in the mean, speciation, and e would be what some might call punctuated gradualism.

[Image: outil_bleu09_img02.jpg]
(the y-axis is labeled funny in this one. I don't know what "evolution" is really supposed to mean here, but we can assume it means either change in allele frequency, for the biologists, or morphological change)

[Image: F1.large.jpg]

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07-10-2015, 06:42 AM
RE: Ask some questions about evolution here.
It's also worth noting that a lot of biologists don't like punctuated equilibrium or Stephen Jay Gould, who along with Niles Eldridge first postulated it as an alternative model to gradualism. It is in part because because of the way Gould and Eldridge presented it (they implied that gradualism was wrong and only punc eq was correct, which ruffled a few feathers as it were).

In some cases, they are probably correct. Biologists tend to study evolution over shorter timescales, meaning that what they are studying isn't net evolutionary change but may be the variability about the mean during stasis. This is almost certainly true for some studies/species, but not likely for all. (biology textbooks tend to ignore punc eq, and some actually just get it flat out wrong)

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08-10-2015, 04:17 AM
RE: Ask some questions about evolution here.
(06-10-2015 04:52 AM)EvolutionKills Wrote:  
(06-10-2015 04:40 AM)DLJ Wrote:  Do we like honey because it's sweet?
Or
Is it sweet because we like it?
Both.

YaBut are our domesticated plants and animals doing our bidding or are we doing theirs?

Give me your argument in the form of a published paper, and then we can start to talk.
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08-10-2015, 06:53 AM
RE: Ask some questions about evolution here.
(08-10-2015 04:17 AM)Hafnof Wrote:  ...
YaBut are our domesticated plants and animals doing our bidding or are we doing theirs?

Yes.

Yes

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08-10-2015, 07:02 AM
RE: Ask some questions about evolution here.
(08-10-2015 04:17 AM)Hafnof Wrote:  
(06-10-2015 04:52 AM)EvolutionKills Wrote:  Both.

YaBut are our domesticated plants and animals doing our bidding or are we doing theirs?

animals, both

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08-10-2015, 04:51 PM
RE: Ask some questions about evolution here.
(07-10-2015 06:31 AM)TheBeardedDude Wrote:  
(06-10-2015 10:11 PM)Chas Wrote:  Punctuated equilibrium is not actually a real thing; or it's just evolution.

It depends on the timescale you use to view change. If you zoom in on the timescale, all change is gradual; if you zoom out, some of it looks rapid - so rapid that it looks like a sudden change.
But it's not sudden, just more rapid than when there is little change in selection pressure.

If the selection pressure stays constant, there will be little change in the genome other than random drift.

It is when selection pressure changes that we see much change, and large changes in selection pressure, though more likely to cause extinction, might cause rapid change in the genome.

But that's just the evolution algorithm.

No, punctuated equilibrium is different. It isn't only a matter of timescale.

No, that's just like the micro - macro evolution baloney.

Quote:Punctuated equilibrium postulates that some species (not all because some examples of evolution clearly are a better fit for gradualism) remain constant (in stasis) with respect to their morphological disparity over time (with the only variability being fluctuations about a mean with no net change) because there is no selection pressure to drive change during stasis.

Which is what I said.

Quote:For instance, we see it quite often in the fossil record (especially with invertebrates like brachiopods and trilobites and bivalves, etc) where some environments are constant for millions of years and as a result, the same species will persist with little to no morphological change over the same stretch of time.

Which is what I said.

Quote:Basically, if there is no selection pressure to drive morphological change, there won't be any morphological change.

Which is what I said.

Quote:That is the equilibrium part of it (stasis). But periods of stasis are punctuated by intervals of rapid change. This rapid change is some alteration to the selection pressures that had remained constant, that then drives either adaptation (and therefore morphological change) or extinction.

Which is what I said.

Quote:So, gradualism is essentially constant change over time (no meaningful deviation from the rate of evolutionary change) but punctuated equilibrium are periods of stasis (no net change) punctuated by rapid (short intervals of time) evolutionary change. For the first image, the horizontal lines represent no net change in the punc eq model, in reality it would be more like b in the second image where there is variability but no net change. In the second image, c (or a) would be similar to punc eq. where a change in selection pressure causes a shift in the mean, speciation, and e would be what some might call punctuated gradualism.

I did not contrast "punctuated equilibrium" with "gradualism". I am saying all of evolution is punctuated equilibrium; they are one and the same. There aren't two kinds of evolution.

Quote:[Image: outil_bleu09_img02.jpg]
(the y-axis is labeled funny in this one. I don't know what "evolution" is really supposed to mean here, but we can assume it means either change in allele frequency, for the biologists, or morphological change)

If you stand back, both pictures look the same.

Quote:[Image: F1.large.jpg]

Sorry, what's the point of that pic? Consider

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08-10-2015, 04:52 PM
RE: Ask some questions about evolution here.
(07-10-2015 06:42 AM)TheBeardedDude Wrote:  It's also worth noting that a lot of biologists don't like punctuated equilibrium or Stephen Jay Gould, who along with Niles Eldridge first postulated it as an alternative model to gradualism. It is in part because because of the way Gould and Eldridge presented it (they implied that gradualism was wrong and only punc eq was correct, which ruffled a few feathers as it were).

In some cases, they are probably correct. Biologists tend to study evolution over shorter timescales, meaning that what they are studying isn't net evolutionary change but may be the variability about the mean during stasis. This is almost certainly true for some studies/species, but not likely for all. (biology textbooks tend to ignore punc eq, and some actually just get it flat out wrong)

They were arguing against a gradualism straw man of their own making.

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08-10-2015, 04:58 PM
Ask some questions about evolution here.
No, they weren't arguing against a straw man version of gradualism. They were arguing that gradualism is a short term phenomenon that assumes the variance within stasis is evolution.

Gradualism is one model of evolution. Punctuated equilibrium is another. It has never been proposed as a different kind of evolution.

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