no,

I m with Slimebeast and the others

Adaptation DOES NOT EXIST or HAS NEVER BEEN PROVEN.
You dont adapt to your environnement. You are selected by it, this is different.

Whatever, here, we have NO proof that this is evolution.

- are these lizard able to do this usually ? or not ? Is it a new trait ? or something that was already existing ?
I dont know if this question is answered but this is REALLY critical. Because, if it is something this specy is able to do classically, then, this is not evolution.

- are we able to determine a genetic change ? The genome has to be sequenced and the 2 groups have to be genetically different at least for some groups of genes implicated in "the birth style". It has to be proven too by creating mixed individu and isolated the critical genetic sequence implicated in the style birth process.

REALLY, Slimebeast is right to play with the words : THIS is not evolution until it is proven to be evolution
Evolution is not about Adaptation, Evolution is about Selection of different variations. 
We have no proof of selection and we are even lacking proof of variations (true specific and isolated trait or genetic difference).

It is funny to see, it is funny to read, but this is not definitive.

Thing is, as it stands the article doesn't seem to show that any further (relative to other conteporaneous populations) adaptation occured. If there's any genetic difference between the populations than yeah, they're diverging and evolution is showing itself. Otherwise, if they're simply making use of a trait that's already present in every population, withouth change or enhancement, than there's not nearly as much to see here.

Also, as libe said, you don't really adapt to the enviroment, the enviroment adapts you :)

I don't see how one branch dying has anything to do with it though.

I don't get it, all I'm doing is supporting the cold climate model of viviparity. I'm not saying evolution has occurred, I'm saying it will occur if the environmental pressures remain. The first steps of a new phase of evolution for this lizard if you will.

Why does everyone seem to keep think that I've said evolution has already occurred? I'm saying it is likely to occur in the future.

I'm sticking by the cold climate model because it is well supported already. We've observed this evolution several times before in extremely similar lizards, which has been very strongly linked as the result of the cold environment.

"Evolutionary origins of viviparity among the squamate reptiles (which skinks are) are strongly associated with cold climates, and cold environmental temperatures are thought to be an important selective force behind the transition from egg-laying to live-bearing."

(source)

Cold environments  (as well as several other factors) are already strongly linked with the evolution of vivparity. My whole point is that if the cold environments persist, then these lizards will eventually evolve to become viviparous as a result of the selective pressures. As I've mentioned in a previous post, many examples of this exist.

Slimebeast is saying that this doesn't take place, that the mechanism for retaining the eggs will not lead to an evolution. That's what his jumper analogy was about. Or at any rate he's saying that the selective pressure of the cold environment will not lead to an evolution in this species, which goes against the already strongly supported cold climate hypothesis.

Not correct. I didn't say that. I said that the observations of this lizard presented in the article, namely that cold weather triggers the lizards to retain their eggs longer, is not evolution in action.

Then I said that if we are to draw those conclusions we need data to support it by either seeing a genetical difference between the northern and southern pop when it comes to regulation of egg retainment, or by seeing further evolutionary steps between egglayers and full-placenta live births in nature. And to the latter superchunk came up with the Platypus.

Yup, I don't think any of us was arguing this can't lead to a different birthing system. But look at the tittle. "Evolution at work". This is more like "Things are in place for evolution to work".

(Of course "evolution at work" is tongue-in-cheek as it's not something that can be toggled on and off :P)

Erm, that is the next step in this whole thing, right? The snakes who's genes are unfit to give live birth will slowly die.

...?

"REALLY, Slimebeast is right to play with the words : THIS is not evolution until it is proven to be evolution
Evolution is not about Adaptation, Evolution is about Selection of different variations. 
We have no proof of selection and we are even lacking proof of variations (true specific and isolated trait or genetic difference)."

That isn't correct, evolution isn't natural selection. Evolution is the change in a species over generations, natural selection is a mechanism (and not the only mechanism, there are others such as genetic drift)  for evolution to occur, not the definition of evolution itself.

Fine.

Viviparous evolution in squamates, which skinks are, has been observed many times (100 ), and the evolution has been strongly linked to the cold climate model. That is those lizards which remain oviparous in cold climates (as well as several other selective pressures) produce fewer and weaker offspring, while viviparous lizards, those that are better at egg retention, produce more offspring and become more dominant. Over time the egg shell thickness is reduced and eventually evolves into complex placenta, which has been observed several times.

"Squamate reptiles provide an excellent model system for studies on the evolution of viviparity because live-bearing reproduction has evolved in the Squamata at least 100 times (Blackburn, 1999), and complex placentae have evolved four or five times (Thompson and Speake, 2006)."

(Source) (sorry to use this twice, it just demonstrates my point)

It has been shown through observed placentation of lizards.

The following is an explanation of the evidence and cases for the stages of the evolution of the placenta in squamates, that the skink will likely follow if the evolution becomes successful. (Sorry about the wall of quoted text, it's just that I originally wrote out an explanation myself, but my browser crashed and lost it *grrr*. and this explains it better than I can anyway) (source)

"Multiple forms of squamate viviparity and placentation have evolved, each involving modification of extra-embryonic and uterus membranes from an ancestral oviparous pattern. Most squamates reproduce by simple yolk-dependent (lecithotrophic) viviparity, featuring retention of large, yolk-rich eggs, eggshell reduction to a thin membrane, and limited exchange of nutrients for growth (histotrophy) between the uterine epithelium and isolated yolk mass omphalopleure. Accepting the definition of Mossman (1937) that a placenta is “any intimate apposition or fusion of the fetal organs to the maternal (or paternal) tissues for physiological exchange”, this arrangement has been termed an ‘omphaloplacenta’.Gas exchange occurs across the well-vascularised interface between the outer-most embryo-derived membranes (the chorion and allantois) and the directly apposed uterine epithelium: this simple juxtaposition of fetal and maternal epithelia is technically termed a Type I or ‘epitheliochorial chorioallantoic’ placenta.

Moving on to consider other forms, some members of the Scincidae (e.g. Niveoscincus spp.) have a morespecialised, Type II, placenta. Here the chorioallantoic placenta comprises a layer of large, cuboidal chorion cells closely associated with a ridged uterine epithelium of flattened (or ‘squamous’) cells, underlain by a dense capillary network. Yet more complex, Type III placentation is seen in a number of Australian skinks (e.g. Pseudomoia spp.) and the Mediterranean lizard Chalcides chalcides. This morphotype is typified by differentiation of part of the chorioallantoic placenta into extensively folded, interdigitated uterine and chorionic epithelia. This structure is specialised for matrotrophic nutrient transfer, and is termed a ‘placentome’. Surrounding the placentome, gas exchange is facilitated by a ‘paraplacentome’ comprising microvilliated, enlarged chorionic epithelial cells apposed to a highly vascularised uterine epithelium.

Finally, in the most advanced, Type IV placentation morphotype, famously found in the South American genus Mabuya, complex adaptations converge in intricate detail upon the derived placentation of eutherian mammals. Placental features shared between mabuyids and eutherians include a placentome of densely folded fetal-maternal epithelia, and a surrounding chorioallantoic placenta (paraplacentome) covered in clusters of cells (chorionic areolae) specialised to absorb products secreted from complementary uterine glands, and giant, binucleate chorion cells covered in microvilli. Adding to the list of remarkable convergences, both Mabuya and eutherians also ovulate minuscule (~1mm) yolk-free ova, provide >99% of embryonic nourishment by placentotrophy, and do so over a protracted gestation period (8-12 months)."

Anyway, now to defend my point about it being evolution in action in this particular Skink. I believe that the selective pressures that form the eventual evolution which have been observed in other squamate are already happening in this case, and it will continue to do so if they continue to live in the cold environment over the coming generations and eventually they will develop more complex placentas. Even though it is early stages, this is the first step for this particular evolution for this lizard that will follow a path that many similar lizards have taken in the past. It may not be a significant evolution yet, but it is evolution that has been set in motion.

As the article said.

"Now we can see that the uterus secretes calcium that becomes incorporated into the embryo—it's basically the early stages of the evolution of a placenta in reptiles" 

Sorry I cut your text, I hate long quotes (I mean forum quotes, not like what you did :P)

As I said before, sure this is most likelly (we can't be quite sure since so much could happen to stop it) the start, or the early stages, of evolution of this trait. The other squamate sure point this way. But the idea is that if they had (or have, I don't know) actual differences compared to other populations, it'd imply not only that evolution is "being set in motion", but that it's actually happened  there and still happening. It would be more interesting and qualify better as evidence.

The way it is right now, it uses the theory (and prior evidence) to suppose what'll probably happen, instead of saying "See, these two populations have diverged genetically in accordance to their different environments, and should continue doing so, just as expected".

Now, not that I think evolution needs any extra evidence, but it'd be more interesting.

That little guy is adorable!