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swan42 -> RE: Documented evolution of new functions and behaviors in bacteria (5/10/2008 12:01:01 PM)
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ORIGINAL: Real_Solitude
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ORIGINAL: drmark
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I hardly expect anyone's biases to be overcome, but this is capital 'C' Cool stuff. What's even COOLER is that Pseudomonas aeruginsa was first characterized as a species in 1872 and has NEVER evolved into any other kind of bacteria in over 135 years. This is equivalent to approximately one million generations of Hominids (surely ample time for monkeys to turn into men!). Creation according to kinds leads to stasis which trumps evolution once again!
Forgive my squirrely ignorance, but I've a few questions.
Do you mean that every every strain of Psudomonas aeruginsa (aeruginosa?) still exists as Pseudomonas aeruginsa, or that there is a strain of Pseudomonas aeruginsa that still exists as Psudomonas aeruginsa?
The first would be quite hard to substantiate, which is why it should be the burden of someone who wishes to prove that it has evolved, rather than the opposite. However, there can still exist a strain of PA that is still PA while another group of that strain has become something else. Divergent evolution is the term, I believe.
This isn't to say that it has happened, but merely that point out that PA still exists isn't really a point in your favor.
However, is there any reason that this bacteria should have evolved? Has there been a dramatic change to their environment in the past 135 years? Are they inefficient at something they do, as to allow for adaptation to better suit that role?
From my understanding of evolution, if something is well suited to its environment, and the environment does not change, you will not see the species evolve simply because any mutation will move it further from the 'ideal' for that environment.
It's bad form, when someone presents evidence that a form of bacteria has evolved to say, "But this one hasn't!" It really doesn't help your argument at all. The fact that one did would be strong evidence for evolutionary theory. The only way to void his point is to show how Nylonase isn't an example of evolution, not by stating that another bacteria hasn't evolved in X years.
I'll be a little less quick to say "yes" (which question was that a yes to gluadys?) the way gluadys has.
We can say only a few things about P. aeruginosa and nylonase.
1. Nylon did not exist on this planet until 1935
2. All other bacteria do not digest nylon
3. A strain of Pseudomonas aeruginosa emerged to occupy the niche defined as a nylon rich environment
Whether these facts (yes these are indisputable facts) are a 'no', 'yes', or 'maybe' to your questions requires more work.
To the first question, there exist P. aeruginosa which cannot digest nylon. I'd say it is too much to define this new strain of P. aeruginosa as a new species. That's an encyclopedic answer not deduced from information about nylonase.
"Is there any reason that this bacteria should have evolved?" is a less than perfect evolution question because it invokes satisfying concepts like cause and effect. Explanations that are satisfying have too much power over the human mind. I'd rather ask, "Is there a reason this strain of bacteria survives to the exclusion of all other bacteria?" Answer: Yes, bacteria all other bacteria yield sub-optimal growth in a nylon rich environment because they do not have nylonase.
It is really a separate question to discuss "How did nylonase come to be?". Based on the previously listed facts about P. aeruginosa and nylonase, we cannot answer that question. Nylonase may have always been present in a small minority of P aeruginosa. Nylonase may be a slight modification of an existing enzyme. Nylonase may have been acquired intact by P. aeruginosa through a process of plasmid transfer from a completely different species of bacteria and may require a collection of enzymes already present in P. aeruginosa in order to digest nylon as food.... for us to discover this discovery in the first place.
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