Punctuated equilibrium

[MatthewG215]

I find this interesting... any thoughts?

"Punctuated equilibrium, or punctuated equilibria, is a theory of evolution which states that changes such as speciation can occur relatively quickly, with long periods of little change—equilibria—in between. This theory is one of the proposed explanations of the evolutionary patterns of species as observed in the fossil record, particularly the relatively sudden appearance of new species in a geologically short time period, and the perhaps typical lack of substantial change of species during their existence."

http://en.wikipedia.org/wiki/Punctuated_equilibrium

 

[Illuminatus]

Makes sense. A period of geological or environmental change will shake up the natural selection bag, so to speak, more than a calm period would.

 

[Yamialpha]

It's an interesting theory, although my question is does it adequately explain the Cambrian explosion?

 

[AV1611VET]

I find this interesting... any thoughts?

Punctuated equilibrium is still macroevolution.

God's "punctuated equilibrium" doesn't involve the animal kingdom being interconnected.

Each species was an incipient of dust or water.

 

[crjmurray]

David Sepkoski summed up punctuated equilibrium very well for me in an email. I'll find it and post it later today.

 

[AV1611VET]

David Sepkoski summed up punctuated equilibrium very well for me in an email. I'll find it and post it later today.

In the meantime, let me sum it up.

Punctuated equilibrium is a joke.

 

[Loudmouth]

I find this interesting... any thoughts?

"Punctuated equilibrium, or punctuated equilibria, is a theory of evolution which states that changes such as speciation can occur relatively quickly, with long periods of little change—equilibria—in between. This theory is one of the proposed explanations of the evolutionary patterns of species as observed in the fossil record, particularly the relatively sudden appearance of new species in a geologically short time period, and the perhaps typical lack of substantial change of species during their existence."

http://en.wikipedia.org/wiki/Punctuated_equilibrium

Many of the ideas can be traced back to Darwin himself.

Only a small portion of the world has been geologically explored. Only organic beings of certain classes can be preserved in a fossil condition, at least in any great number. Widely ranging species vary most, and varieties are often at first local, -- both causes rendering the discovery of intermediate links less likely. Local varieties will not spread into other and distant regions until they are considerably modified and improved; and when they do spread, if discovered in a geological formation, they will appear as if suddenly created there, and will be simply classed as new species. [Charles Darwin, Origin of Species1st Edition 1859, p.439]​

That is one of the essential parts of PE as described by Gould and Eldredge.

 

[HitchSlap]

In the meantime, let me sum it up.

Punctuated equilibrium is a joke.

Right, because 2,000 year old, pseudonymous, anonymous, fictitious myths and fables, always outweigh solid empirical objective evidence.

 

[Loudmouth]

In the meantime, let me sum it up.

Punctuated equilibrium is a joke.

You think facts are a joke.

 

[AV1611VET]

You think facts are a joke.

Are you defending punctuated equilibrium?

And are you saying facts point to punctuated equilibrium?

If so, what about the facts that led to Phlogiston theory?

 

[Loudmouth]

Are you defending punctuated equilibrium?

And are you saying facts point to punctuated equilibrium?

Yes, facts point to punctuated equilibrium. There are many examples of PE occuring in the fossil record:

New species of Phacops evolved allopatrically along the margins of the pre-existing species range; they then migrated back into the environmental and geographic range of the ancestral species, whence they became abundant. After the initial speciation events, species of Phacops show no significant morphological changes until they go extinct millions of years later. Gould (in Eldredge and Gould 1972) described a remarkably similar pattern involving Pleistocene lands snails (a few hundred thousand years old) from Bermuda referable to Poecilozonites. Again, new snail species, this time differing in subtle shell characteristics, evolved allopatrically, and showed no significant change after the initial speciation event.
http://www.scholarpedia.org/article/Punctuated_equilibria​

If so, what about the facts that led to Phlogiston theory?

What about the facts that led to oxidation theory?

 

[AV1611VET]

What about the facts that led to oxidation theory?

What about the facts that led to Thalidomide being marketed as a prenatal wonder drug?

 

[Loudmouth]

What about the facts that led to Thalidomide being marketed as a prenatal wonder drug?

What are the facts that showed thalidomide to be a safe drug for pregnant women?

 

[crjmurray]

"Evolutionary stasis can happen through a phenomenon called stabilizing selection, in which random small genetic changes in a large population of organisms don't be come "fixed"--that is, they aren't preserved in the population--because OTHER small random changes, in the opposite direction, balance them out. This usually happens when these small random changes don't offer an adaptive advantage to the organism--say, thicker fur that keeps an animal warmer in a cold environment and gives it a reproductive advantage over other animals in the same species. In a very large population living in an environment that doesn't change very much over a long period of time, and where the gene pool is very large, stabilizing selection can produce this kind of evolutionary stasis. According to the theory of punctuated equilibrium (which some, but not all, evolutionary biologists support), if a small group of organisms are separated from that larger population--say, a group of birds that get blown out to sea in a storm and settle on a small island--that smaller population can "suddenly" (i.e., over perhaps several thousand years) experience rapid evolutionary change, because a) the new environment may present new challenges in which random or recessive mutations are suddenly advantageous, and b) in a much smaller population new genetic mutations have a higher chance of becoming "fixed" in that population."
- David Sepkoski

 

[sfs]

In the meantime, let me sum it up.

Punctuated equilibrium is a joke.

Don't quit your day job.

 

[sfs]

It's an interesting theory, although my question is does it adequately explain the Cambrian explosion?

It has nothing at all to say about the Cambrian explosion. The Cambrian explosion is about the appearance of major new body plans -- the large-scale organization of animal bodies. PE is about more or less sudden shifts between very closely related, morphologically similar species

 

[Chalnoth]

It's an interesting theory, although my question is does it adequately explain the Cambrian explosion?

The Cambrian explosion was a period of about 10 million years, and we now know that many of the changes previously attributed to the era actually happened much earlier: it's just that during the Cambrian hard shells evolved, which fossilize much more readily than soft bodies. There's some supposition that the evolution of eyes may have driven the evolution of defenses like shells in many organisms.

 

[Gracchus]

In the meantime, let me sum it up.

Punctuated equilibrium is a joke.

Maybe so, AV1611VET, but we aren't laughing with you, we're laughing at you.