Xixax

I have it bookmarked, and will take a look at it. Probably get to it this weekend.

Because mutation continues regardless of how adapted an organism is to it's environment. Also, these organisms may by a force other than choice be placed into a new environment where they are no longer as equally adapted. Again, instead of dropping the features that made them adapted to the previous environment, mutation may provide a new 'feature' that makes them better adapted to their current environment. I'm an undergrad, and I feel a bit sheepish even touching things this inherently simple with someone who should know them already.

Then is there much of a point in bringing it up if you feel the material is too 'long' to post here?

If you're going to make a point that it should be abandoned here, at least take the time to explain why. Pointing me to various books is great for the long term, but it doesn't add anything to the discussion unless you provide excerpts, or at least your summary of what is said there.

You still haven't presented anything that isn't consistent with Darwinian evolution in your posts, other than the statement that natural selection can only reduce complexity.

I've left my explanation of complexity at the very end. I would start with, in the way in which I intend it to be read in reference to an organism and evolution: A combination of expressed features that work to aid it's survival.

I'm sure others with more time could do a much better job, but when I say complexity, that is what I'm referring to here.

Nat

"What is the cause of evolution, natural selection or mutation (if those are the two alternatives)?"

They aren't the only two, but if you expand them to be descent with modification and selection, I would answer that they are both really needed for an allele frequency to change in a population. Without a change (descent with modiciation) there is nothing for selection to filter, and without a selection mechanism any change would be unnoticable in the population.

"Can evolution occur in the absence of mutation, given those constraints? I doubt it."

Actually, yes it can. A mutation is not actually required. An existing allele can be selected for by a change in the environment.

"Can evolution occur in the absence of natural selection? Yes, due to mutation pressure or meiotic drive (but I forget what this is)."

I don't see how any mutation could be propogated throughout a population without some sort of selection pressure. For example, an unexpressed mutation may continue to exist in the genome for many generations, but it is extremely unlikely to spread through the population at a faster rate than any other unexpressed gene.

"Is evolution inevitable given natural selection? No. Stabilizing selection results in no change."

True, but given a changing enironment (something that is hard to deny), natural selection will necessarily drive changes in allele frequency unless the changes to the environment are so severe that they result in extinction.

"Can mcaroevolution be the result of selection?"

Not just selection. Potentially over extremely long periods of time genetic drift with a slowly changing environment and thus slection pressure could result in true macroevolution without any new mutations.

"Damn hard to demonstrate, which is a point Philip Johnson makes very good use of."

Johnson is a fool - he only convinces religiously motivated cretins.

"And what were Darwin's other mechanism of evolution?"

Of course he knew nothing of the genome so he couldn't come up with mutations, but he did come up with descent with modification. Small changes from parent to offspring that are selected for over long periods of time results in species diversification. This is essentially the same Theory of Evolution used in the Modern Synthesis - Darwin simply lacked the requisite molecular biology understanding to understand what was causing the descent with modification.

"The effect of the environment which, by the time you wade through the Victorian English, is a form of Lamarckian inheritance."

The effect of the environment is the selection pressure - not what causes the genome to change. Lamark didn't recognize this - Darwin did. That is why Darwin is considered the founder of the theory of evolution by natural selection and Lamark is seen as someone who had some early ideas that were later found to be quite wrong.

Albion

The cause of evolution is variation and selection. Mutation is one way of creating variation, and natural selection is one method (probably the major method) of selection. Darwin - unlike Wallace - realised that natural selection wasn't going to be the only method.

Yes. Artificial selection works pretty well. Then there's genetic drift and the founder effect. Natural selection isn't the only mechanism, it's just the best known.

I think it is inevitable, given both variation and natural selection.

Why not? It's the result of a lot of factors, including selection. So, in that sense, it's a result of selection. Selection is necessary but probably not suffcient.


The effect of the environment is part of selection. Lamarckian inheritance involves inheritance of acquired characteristics, which has no more to do with the environment than natural selection does.

And I STILL don't see what Darwin's perceived deficiencies of character have to do with any of this.

Motorcycle Mama

Albion,

I use your post for a final comment and then I quit. This is a matter of convenience and nothing else.

I have read in the most recent posts comments on evolution that, for a proper response, would take me about a week. I have little desire to do that and I suspect most of the readers of these posts aren't that interested. I have mentioned things that might be read and in that I include Lamarck's Zoological Philosophy or Burkhard's book, The spirit of the system which is about Lamarck. Quite frankly Albion, you got it wrong. The main thrust of evolution, to Lamarck, was an internally directed drive towards increasing complexity. The effect of the environment was noted by the branching pattern seen in evolution and was the result first, of the incorporation of acquired attributes and, providing both parents had the same acquired attribute it would be inherited by the offspring.

Respond if you wish, but it won't be read.
MM

Jack the Bodiless

Well, this might be a waste of time, but...

Darwinian evolution is all about random mutation AND natural selection. It always has been (though Darwin, ignorant of genetics, referred to "variation" rather than "mutation"). They have always gone hand-in-hand. I am surprised that you were unaware of this.

And Albion is entirely correct: Lamarckian inheritance involves inheritance of acquired characteristics, which has no more to do with the environment than natural selection does.

That isn't equivalent to saying that environmental effects are irrelevant in either view. In Darwinian evolution, it determines natural selection: in Lamarckianism, it determines the environmental stresses that cause the acquired attributes to occur.

But we now know that Darwin was right and Lamarck was wrong.

Xixax

Ok, that's irritating as hell. I don't understand arrogant sobs like this even bothering to take the time to post in the first place.

Post and run.

Albion

I see I didn't get a response to my question about what Darwin's perceived character defects have to do with the correctness of his theory.

pz

...or whether it is rightfully 'his' theory.

Motorcycle Mama

Point well taken. I apologize for the arrogance.


Three points.

First, why is invoking natural selection an argument based on faith, something I said but then refused to elaborate for which I was, quite rightly, criticized. The basic argument is that if natural selection is the cause of evolution then attributes that can be related to natural selection will be seen in the products of evolution, e.g., species. So you can verify that hypothesis by finding such attributes. But, by the same token you can falsify that hypothesis by finding attributes not related to natural selection. One may wish to say features not related to natural selection are correlated with those that are but in the absence of any evidence such a statement is one designed to save natural selection in the face of falsification. What these views summarize to is, "Evolution is caused by natural selection but there is no evidence that such occurs." Yes I know the evidence for population differentiation through natural selection but a population is not the same thing as a species.

Second, would those who comment on Lamarck please read what he had to say. As I said in previous post, to Lamarck the most important thing about evolution was an inevitable drive towards increasing complexity. With respect to acquired attributes it was the incorporation of acquired attributes that was primary, inheritance was secondary. What I forgot to mention, an admitted failing, was that attributes were acquired as the result of organisms sensing they were under stress and adjusting their bodies to relieve that stress. What Lamarck produced was a theory of environment/organism interaction that would exclude the argument from design.

Third, with respect to complexity, a good definition is the length of the algorithm required to describe something, or the amount of information, in say, e.g., bits, necessary to describe something. Some interesting views on complexity and information are in Jeremy Campbell's Information theory language and life.
MM

Motorcycle Mama

It is a truism of the Jesuits, there is never a partial man, only the whole. Someone willing to put acceptance above understanding, the interpretation I attached to the descriptions of Darwin, then at what point can one be sure that you are seeing accuracy and at what point an attempt to assure acceptance.

By the way, Lyell wrote Darwin pointing out that his analogy of artifical selection with natural selection raised a problem. In artifical selection the selecting agent was human, how then did Darwin know that in natural selection the selecting agent was not God? Darwin never answered.
MM