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Jhud -> RE: Documented evolution of new functions and behaviors in bacteria (4/25/2008 12:14:44 AM)
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quote:
If the only change to the organism is the way that the genes are regulated, then that would mean that no new information was added. Clumping the changes that were seen into the term "evolution" gives the thought in the mind of the reader that a new and novel characteristic has been displayed, but in reality, a capability that was already present, though dormant, is simply being expressed. This is a strong indication that the organism was designed because all of the information was already present in the organism. It simply wasn't being expressed until there was a stressful situation to cause it to come to the surface through changes in regulatory genes.
My question is, are the changes to the regulatory genes mutations in the way that we normally think of mutations.
Well, let's see if I can help shed a little bit of light on it all.
To start with your last question first, a mutation, to steal what seems to be a pretty good definition on Wiki, are "changes to the nucleotide sequence of the genetic material of an organism".
This is a very broad description that encompasses copy errors, deletions, duplications, changes to a single nucleotide, changes to the way the information is read, changes to whole segments in a genome, etc. Some of these change the nature of the information conveyed, some of these merely amplify the information that exists (often in the case of duplications), and some of these reduce the amount of information available.
In terms of gene regulation, a mutation like a gene duplication can indeed affect the way a gene is expressed (and incidentally that is primarily what gene regulation does; changes the product of a gene in some way), often increasing the expression of something that the gene produces.
So if for example the gene controls the thickness of cell wall thickness, or the production of pumps that remove toxins from a cell, or even limb growth, duplications of that gene can cause enhance the expression of those genes to create thicker cell walls, or more pumps, or longer limbs. In this sense it acts like a regulator.
That being said, the cell has built into it many regulators, some of which are in the structure of the DNA itself, some of which is a product of transcription by RNAs, and some of which are the product of proteins in the cell itself.
These mechanisms act like amplifiers, buffers, switches, and inhibitors. They can affect an organism during the course of its development during growth, or affect aspects of reproduction or responses to the environment during the life of the organism. These effects are the product, as you said, of the changes in to the expression of already extant genetic information.
In fact, it can be applied to presumed examples of evolution cited around here recently, namely the changes that occurred in the ‘domestication’ of foxes in Russia. Many of the changes there are thought to be the result of the regulation of the development of characteristics of typically mature foxes; in short the foxes retain those aspects of immature foxes – docility, playfulness, larger heads in comparison to there bodies, etc. It a regulation to the development of the foxes in response to the selection factors – but it isn’t the development of novel structures and capabilities.
New regulatory processes are being discovered and described. Many phenomena that were previously thought to be classic cases of evolution are now known to be the product of such processes; antibiotic resistance, the size and thickness of Galapagos finch beaks, the patterning in butterfly wings, etc.
So hopefully that helps.
One note about IDists with regard to mutations.
IDists do not deny mutations exist, or that they can produce changes to an organism. Indeed, anyone who has read Behe’s The Edge of Evolution can read an entire book discussing what mutations can and can’t do, and what Behe (and myself) find improbable to the point of dismissal is the idea that the gradual accumulation of specific individual mutations can produce complex novel structures, capabilities, and body plans in an organisms.
Another distinction is that evolution is typically seen as an arms race; organisms competing for survival develop increasingly sophisticated structures to deal with those forces that would eliminate them.
Behe systematically laid out the case that this is not what we actually observe; instead we see ‘trench warfare’ where organisms will employ either extant capabilities in novel ways, or even diminish capabilities in an all out attempt to deal with obstacles to survival.
And that is why I would like the details about how the HIV virus is developing resistance; I suspect it reflects a simple mutation which simply disallows a protein from doing what it did before, and not a novel capability in response to the antiviral medications.
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