To recap: Darwin’s theory, known as Darwinism, was developed by Charles Darwin’s observations of both fossil finds and exotic animals he observed during his time on the HMS Beagle. His theory, published in 1859 , was this: there is natural variation amongst animals and plants and that variation might be naturally selectable over very long time frames to produce plants and animals that are different from the originals. Further, all plants and animals, in fact, all living things might have come from just one single ancestor. These theoretical premises became known as variation, natural selection, gradualism and common descent. Darwin also accepted Lamarckism, which posited that acquired characteristics or features might also be heritable.
Given that the DNA variability under discussion is subtractive, not additive, there is no reason to think that the variations are not just subsets or subspecies of the main, overall species, which still exists.
Since the time frame assignments are based on differences in the number of common DNA markers seen, and there is no actual clocking mechanism involved other than this inference, there is no reason to think that this is meaningful, especially since the markers are not defined as to purpose, and might be meaningless to the presumed speciation.
To summarize: given the stated ability to cross-breed, plus the existence of members of the original population, and the lack of any reason to think that there was speciation based on new features, the conclusion follows that this is consistent with variation within a genome: subspeciation; not with evolution beyond the original genome.
After more than 33,000 generations and “billions of mutations”, strains of Cit+ e-coli were found, and the colonies became dominant, although sharing the plates with original Cit- e-coli colonies.
The experiment was designed with built-in replicability by having frozen samples of the cultures at every 500 generations. This allowed the experimenters to “rerun” the experiment through the development of the Cit+ strain, to see if it would repeat. If it did repeat, it would mean that a prior, “historical” event must have been present. The Cit+ strain did, in fact, appear in the repeated experiments. This means that even with a different mutation experience, the Cit+ strain appearance was inevitable in these colonies.
“In any case, our study shows that historical contingency can have a profound and lasting impact under the simplest, and thus most stringent, conditions in which initially identical populations evolve in identical environments. Even from so simple a beginning, small happenstances of history may lead populations along different evolutionary paths. A potentiated cell took the one less traveled by, and that has made all the difference.”
The results are therefore indeterminate in the sense of knowing whether a new feature has been developed, or a long dormant one has been re-enabled, epigenetically. Until this is resolved, the appellation “evolution” – in the long-term, new feature, new creature sense – is not appropriate. The use of “evolution” to cover any change whatsoever is the sense in which it seems to be used here. I don't agree that it is less parsimonious to assume that a dormant gene is being revived; I think that testing should be done first, and conclusions drawn later.
This is a well designed experiment that deserves watching as new sub-experiments are designed and implemented, and as more definitive DNA analysis resolves the issue of what the Cit+ mechanism actually consists.
lizards in the introduced population of Pod Mrcaru has apparently
also resulted in the evolution of cecal valves, a structure
previously unreported for this species and rare in this family and
scleroglossan lizards in general".
This could be supported or falsified by finding the differences in DNA between the Pod Mrcaru population and its ancestral population, and thus determining if the gene is novel, or if it is previously there, but turned off.
I contacted an author of the paper, Dr. Duncan J. Irschick, to ask if the DNA testing had been done to determine the genetic source of the cecal valve. Dr. Irschick replied, "not yet!"
That seems to put closure on the current claim: it is not known if the "new feature" is actually new, or if it pre-existed in an OFF state, even 6 years later. The fact that a tiny percentage of close relatives do have the feature suggests that the feature might have been necessary prehistorically, but was shut off as the lizard's environment shifted toward high populations of insects, relieving the need for plant matter. Parsimony suggests that the valve did not evolve from nothing in 30 generations, especially given a more likely source.
I also received this message from Dr. Anthony Herrel .
We're still working on getting a handle on those questions. We are
currently analyzing the microbial communities in the lizards from the
two islands. A next step will be to raise lizards from the two islands
in a common environment to test whether the presence of the cecal
valves is genetic or not. Once we have understood these elements we
can then ask the question pertaining to the underlying molecular
Sorry for not being able to address your question yet, but we're
working on it.