Evolution at work? Craziest thing I've seen all day.

[highwaystar101]

Slimebeast said:

highwaystar101 said:

I don't get it? I get it fine, it's you who is (I think on purpose) failing to understand.

No system is ever fully formed, there is always the need for improvement when the environment requires it. Do you think humans just sprouted a fully formed opposable thumb one day? Or do you think it would have evolved from another "fully formed" organ when the thumb offered a new evolutionary advantage? 

In the case of the lizards the environment has changed, which has favoured those who can reproduce with this ability for at least this generation. If this trait is required from generation to generation then an advanced form of this will become the norm for that species. This "fully formed" mechanism will change. If this mechanism is required over an extended period of time an advanced form of this will eventually it will become the common place method of birth.

In the paper they effectively say that if this form of birth is retained over a period of many generations then it will lead to an evolution in reduced egg shell thickness which fits with the hypothetical model. This will be an evolution as a result of natural selection.

The eggs of most viviparous lizards are surrounded by some form of tertiary egg envelope during early stages of embryonic development, but the thickness of this structure is less than that of oviparous species (Blackburn, 1993a, 1998). Reduction in eggshell thickness is believed to be a necessary correlate to the evolution of viviparity because thick eggshells would impede respiratory gas exchange during prolonged uterine egg retention (Packard et al., 1977; but see Mathies and Andrews, 2000). If the evolution of viviparity is preceded by gradual increases in the length of intrauterine gestation, gradual reductions in eggshell thickness should also occur (Packard et al., 1977; Guillette, 1993; Qualls, 1996). This hypothesis is supported by interpopulational comparisons within three species of lizards that demonstrate an inverse correlation between length of uterine egg retention and eggshell thickness (Heulin, 1990; Heulin et al., 1992,2002; Mathies and Andrews, 1995; Qualls, 1996).

(source)

The scientists at work here clearly think that the lizards are genetically changing as a result of this. Thy more than suggest that further adaptation is necessary. You can take this as the proof if you like, but I know that regardless of how much proof I show you, you will never accept it.

You claim to accept natural selection, yet you have shown many times that you reject it, almost as an automated response. The weak don't reproduce, the fit do, the successful traits are passed on to the next generation, this is natural selection at work. Natural selection leads to an evolution.

Yeah I already understood that you see the potential for change in this (I do too, I'm not stupid), you want to talk evolution in general. I well understand that theory , how populations get isolated and how environmental pressure via natural selection works on them to refine genetical traits bla bla bla. A school boy understands that. But that is only theory. Theory =/= reality. We are discussing a specific case here, about these particular snakes.

I repeat (because I was the one who said this article doesn't show evolution at work and you was the one who opposed me): You have the burden of proof to show that the northerners are genetically changed regarding regulation of live birth due to the cold environment. Or else what we read in that article is not a case study of evolution in action.

 

Slimebeast, you know that a study into the genes passed form generation to generation to support live birth in this specific lizard can't be done yet, that's the only reason you're asking for. It's dirty debating. Even if I did prove the genetic change in this particular species you would find something else that's a little more out of range.

We are discussing a particular case, but a particular case which fits into a well documented and understood model. For what it's worth you might as well ask me to go to Jupiter and drop a weight into it and measure the acceleration, so that we can prove that Jupiter obeys gravity like Earth does. We know the model works, we've defined it to the level that every case can use will fit into it. Yes we test the theory frequently, but we can say with a high degree of certainty what the acceleration of an object will be when dropping it towards another planet with a high degree of certainty because the model exists to work it out and it has stood up to rigorous testing. This is just like that.

Unfortunately the future isn't here and I can't yet prove to you that the genes in this specific lizard have changed to a statistically significant level, I'll be happy to do so if you can remind me in a few decades. But in the meantime I know genetic traits are passed on in every species, and I know that only the fit survive to do so. From this I can say with a high degree of certainty that continuing environmental pressures in these lizards will eventually lead to an evolution, like our case with gravity.

We've observed the evolution of vivparity in lizards many times.

"The evolution of viviparity has been well documented and observed many 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). Many of the reptilian origins of viviparity have occurred at low taxonomic levels and in geologically recent times, potentially allowing a reconstruction of the transition to viviparity."

(source)

This case follows the same model as many cases that have been previously shown. I can't prove this case, but I can see that it has many of the hallmarks  of hundreds of extremely similar cases where evolution has occurred. To say that it's not evolution if I can't show you genetic evidence yet is just plain wrong.