For example, if I take a single bacteria of known genetics (because I sequenced it), and subject it to antibiotics - the antibiotic resistant strain will have a CHANGE in the genetics (I know because I sequenced it). What those changes consist of is then studied. But they didn't exist within the population - they were created through changes in the DNA - some of them no doubt through expression of error prone DNA polymerase.
Your explanation fails to account for the above scenario.
Willing to try for a different explanation? The “it was already there” explanation is absolutely incorrect.
And you don’t seem to understand this -— your explanation is just one of the many possible ways of looking at antibiotic resistance.
In fact it can be argued that much of the antibiotic resistance seen “evolving” in bacteria is not due to natural selection acting on genetic mutations, the neo-Darwinian method, but rather technology sharing.
I am not saying that this is the right explanation, simply that we should not shut ourselves out from such possible explanations.
Genes for resistance already exist in plasmids (round segments of DNA) that get passed around from one species of bacterium to another. By means of conjugation, bacteria share PRE-EXISTING genetic information. Those with antibiotic resistance due to mutations have lost genetic information that makes them less fit in the wild.
For instance, a receptor on the cell surface may get damaged by a mutation, prohibiting the antibiotic from entering. But this same mutational damage prevents needed substances from entering, making the bacterium defective. It might outcompete its un-mutated brethren in the artificial world of the hospital, but would most likely lose in the outside world.
A paper in the Nov. 28 issue of Science1 seems to confirm this.
Weigel et al. analyzed the genes of the well-known example of Staphylococcus areus resistance to vancomycin, and concluded it was conferred via conjugation of a plasmid containing the resistance gene.
See here :
Genetic Analysis of a High-Level Vancomycin-Resistant Isolate of Staphylococcus aureus
Weigel, et al.
Science 28 November 2003: 1569-1571.
DOI:10.1126/science.1090956
http://www.sciencemag.org/content/302/5650/1569.full
I am not saying that your explanation is wrong. I am saying that IT IS NOT NECESSARY to insist that Darwinian mechanisms are the ONLY EXPLANATION for what we observe.
That’s what I was saying to the other poster regarding education.
Is there a case where the penicillinase enzyme was observed to evolve in a population where it did not already exist?