EvC Forum: Rapid Evolution in Lizards

“Evolution does not require genomic change. It can, and does, happen that way -- but it is not required. “

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Reposted from Message 15.

Very often valves are not muscular in their makeup but rather they are mesenchymal cells that are secreting lots of extracellular matrix proteins to make the valves more resistant to stress/strain/force so that muscular contraction- an energy dependent event- isn't required for dividing the regions separated by the valves. If this were the case it would take a tremendous amount of changes in gene expression within the muscle but a more simple event to make more mesenchymal cells and valves.

Reposted from Message 15.

Obviously genetics will be important in resolving what's going on, but I don't think it will be any easier to pin down through genetics whether this is a newly-evolved feature or not. The most definitive result (pseudogene present in originating population is activated in Mrcaru lizards) is the one we are least likely to observe. More likely are subtle changes in promoters that alter the concentration or developmental expression profile of growth factors (or their receptors), in which case we are left with much the same question as with morphological studies.

Reposted from Message 17.

No one claimed it was the result of a novel mutation -- I'd actually be very surprised if it were (although new mutations may well have contributed to the phenoytpe). I expect this is the result of selection for novel combinations of alleles in the founder population, plus developmental plasticity.

So what? THAT'S EVOLUTION, TOO.

Please note that "genomic change" is imprecise and vague. Creos usually mean "nuclear genomic mutation". However, alterations/mutations of promoters and alterations of epigenetics are both forms of "genomic change", in the broadest sense of that term.

When I said that "genomic change" is not necessary for evolution, I was trying to speak creotalk for your benefit. I meant "nuclear genomic mutations".

Sounds like name calling? I just wish I knew what this has to do with what we’re talking about!! Not really, It seems like investigating what this fellow thought is an attempt to distract, deride and catagorize my point of view (a prejudicial statement).

Please take the time to google LaMarck.

I am under the impression that there is no change in the genome of this lizard and that this animal has always had an ileum and a cecum, and the ability to digest vegetation, if it would eat such food.

If this were true, you could live on grass.

This valve is a muscular organ and as is the case with all muscles if there is no stimulous (sic) to the muscle you have disuse atrophy. Hence no muscular fold you get a smooth transition from ilium to cecum and the appearance that no ileocecal valve exists (and by the assumption of the investigators no plans in this lizards genome to make one ). The same type of thing happened in this lizards jaw and skull, I purport, that it used its jaw more and the muscles got bigger therefore requiring the stronger bigger bones.

LaMarck redux. And giraffes have long necks because mom and dad giraffe stretched to get at the leaves at the tops of the trees and -- as a result of this stretching -- gave birth to long-necked baby giraffes, right?

Not a fact yet! Gosh, there is a lot of confusion on your side of the fence regarding what is fact and what is theory!

Please see the pictures I posted upthread. It is a fact.

And a VALVE is a body part. A heart VALVE is a body part; a cecal VALVE is a body part.

Maybe someone should look a little harder and deeper in this lizards genus, I think they'll find one.

Another argument from personal incredulity.

Wall lizards of the genus Podarcis comprise 17 species in southern Europe, where they are the predominant nonavian reptile group.

There are over 600 papers written in the last ten years regarding the morphology of this genus.

We know these critters do not have cecal valves.

We’ll see, you just watch, sometime in the not to distant future there will be a follow up article on this lizard on page 62 of the paper in the bottom left corner retracting this ridiculous claim.

Pretty tough to refute an autopsy. (Hint: Pictures posted upthread.)

Thats how it always is with these evolution scientist's earth shattering discoveries; Nebraska man and his cute family of four-from an extinct pigs tooth, piltdown man-man's and ape's skull and jaw hoax, lucy's bones found hundreds of feet apart and in different strattum, neandertal man now known to be completely human, coelacanth a 70 million year old fish that walked out of the water thought to be a missing link between fish and amphibians found in Madagascar fish markets and swimming at great depths in the Indian Ocean. The list goes on!

We try to keep topics narrowly focused here at EvC.

Nebraska Man, Piltdown Man, Lucy, Neandethals, Coelacanth are all OT.

If I've Missed any forgive me, wait forgiving is my side of the fence yours is crushing the weak and destroying those unfit to procreate.

Please try to stay on topic.

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