Uncommon Descent Serving The Intelligent Design Community

The Parameterized Evolution of Dogs

Jonathan Bartlett
August 28, 2010
Evolution, Genomics, Intelligent Design
Share
Facebook
Twitter
LinkedIn
Flipboard
Print
arroba Email

I was digging around for some good examples for a talk I am doing on mutation theory in a few weeks, and came upon this great paper in PNAS – Molecular Origins of Rapid and Continuous Morphological Evolution. Their argument? “tandem repeat expansions and contractions are a major source of phenotypic variation in evolution”. Hmmm…. it almost seems as if these repeats are functioning as parameters to a larger system. That reminds me of something…. Almost like parameterized evolution.

The paper has a great image of repeat-based morphological variation, too:
Canid Skulls.

The primary differences in the skulls are nose bends and midface length, which are governed by a repeat sequence in the Runxp-2 gene. By expanding or contracting parts of this repeat, it affects the shape of the face.

What is also interesting about repeats is that they are also much more mutable than other sequences.

So, it appears that evolution may be parameterized, with systems such as repeats governing what parameters can be modified in the course of evolution.

Comments
And again, about the issue which you seem to take at heart, nothing serious can really be said unless the molecular basis if the changes is known.
I agree with this completely. I think it is silly to compute the odds against structures arising naturally without knowing in detail the events you are computing the odds for. Petrushka
Petrushka: Do you mean that the mutations were guided, or that selection was artificial? I have argued many times, also with you, that those are the best scenarios for ID. Possibly combined. Other scenarios are maybe possible, but I would stick to those two for initial research and analysis. And again, about the issue which you seem to take at heart, nothing serious can really be said unless the molecular basis if the changes is known. This is a general principle. We absolutely have to shift to molecular reasoning, and abandon the vague and often gratuitous inferences based only on morphology on which traditional darwinism has been speculating until now. gpuccio
But probably, designed, guided evolution.
I'm not sure what you mean by that. Do you mean that the mutations were guided, or that selection was artificial? Or some other scenario? Petrushka
Petrushka: I am afraid you are quite obsessed with that... But the answer is simple. I would wait to know more about the molecular basis for that, and the amount of functional information implied, than we will see. But probably, designed, guided evolution. gpuccio
Interesting. How does one interpret the incremental changes in jaw bones leading to the mammalian middle ear? Petrushka
johnnyb: Very iteresting. So, the differences between dog breeds are not due only to allele shuffling, after all. I believe these mechanisms could be well considered as another variant of microevolution (if they are truly random). I quote from the abstract: "The high frequency and incremental effects of repeat length mutations provide molecular explanations for swift, yet topologically conservative morphological evolution." I think here the key words are: "topologically conservative". This really reminds me of what we can obtain using morphing programs, by changing simple parameters. So, I believe that your remark about "parameterized evolution" is absolutely appropriate. gpuccio

Leave a Reply