Re: Evolution in action

Good thing for you, Corinthian, I'm here to put things in truth perspective. The reality is that these lizards are simply exhibiting plasticity upon an environemental change. Lizard legs can grow or shrink depending on needs. You know, Corinthian, how chameleons can change color with backgrounds?....well, here's a secret -- Anoli lizards are much the same -- but instead of color, they can alter their leg morphology according to need. The result is this has nothing to do with evolution. It has nothing to do with selection...it has nothing to do with random mutations. It's just another case of an adaptive phenotype.


http://biosgi.wustl.edu/~lososlab/evolution00.html



Species of Anolis lizards that use broad substrates have long legs, which provide enhanced maximal sprint speed, whereas species that use narrow surfaces have short legs, which permit careful movements. We raised hatchling A. sagrei in terraria provided with only broad or only narrow surfaces. At the end of the experiment, lizards in the broad treatment had relatively longer hindlimbs than lizards in the narrow treatment. These results indicate that not only is hindlimb length a plastic trait in these lizards, but that this plasticity leads to the production of phenotypes appropriate to particular environments. Comparison to hindlimb lengths of other Anolis species indicates that the range of plasticity is limited compared to the diversity shown throughout the anole radiation. Nonetheless, this plasticity potentially could have played an important role in the early stages of the Caribbean anole radiation.

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and another:


http://www.oeb.harvard.edu/faculty/losos/research/


To test this hypothesis, we raised baby anoles on two different surfaces at the St. Louis Zoo--either on 2x4's or on narrow (1/4") dowels. At the end of three months, the lizards raised on broader surfaces had longer limbs than the lizards on narrower surfaces! This suggests that the results observed in the field may be the result of a phenotypic plasticity in limb growth, rather than genetic differentiation. To test this hypothesis, we plan common garden experiments in which we will raise lizards from different islands in similar environments to see if differences in limb length persist. Adaptive phenotypic plasticity has never previously been documented for vertebrate hindlimbs. These findings suggest the intriguing possibility that phenotypic plasticity may play an important role in adaptive differentiation by permitting lizards to occupy different habitats; once subsequent mutations arise, these differences can then be elaborated upon by natural selection.
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too bad, corinthian -- you're outmatched by the truth. You should thank me for keeping you in line. Tweet