Evolution in antibiotic-resistant bacteria validated

[Cap'n Refsmmat]

Here on SFN we've all seen occasional debates about evolution. It's quite common for bacteria to be given as examples of evolution in action: how else could they evolve resistance to antibiotic drugs but through evolution?

 

Of course, the anti-evolutionists respond that the resistant bacteria existed all along -- they just proliferate when the non-resistant bacteria are killed. No new attributes or powers are developed. It's just natural selection in action.

 

Now there's finally good evidence to prove the anti-evolutionists wrong. An interesting article in Molecular Cell shows that antibiotic resistance is due to the action of the antibiotic: several kinds of antibiotics produce free radicals that damage bacterial DNA, causing mutations. Some of these mutations can produce resistance to different kinds of antibiotic, including ones not being used on the bacteria at the time.

 

In other words, antibiotics cause rapid mutation in bacteria, which leads to resistance, even to antibiotics the bacteria has not been exposed to.

 

Cool. The researchers suggest this research can be used to prevent this natural selection, stopping resistant bacteria from appearing.

 

Reference: Molecular Cell, Volume 37, Issue 3, 12 February 2010, Pages 297-298. I don't know if you'll be able to follow the link above to get full text or not, as I'm at university and get university access.

[insane_alien]

Somehow I doubt that this will sway those who don't believe in evolution. If they don't accept any of the rest of the mountain of evidence then another boulder of evidence isn't going to do anything.

[CharonY]

This actually does not add any new knowledge that was not around already. The point is not that ABs lead to resistance against themselves but that they increase mutation rate. Everything falls into place after that.

[Mr Skeptic]

Actually, they would probably take this as proof that they are right -- resistance to antibiotics they are not currently encountering just doesn't "feel" like natural selection. Some bacteria have anti-anti-biotic mechanisms alongside regulatory genes that limit the amount produced, and destroying the regulation results in production at levels that would be excessive in a natural environment. The key is that this can be accomplished via destruction in this case. Remember, they're not questioning the existence of mutations. What you really want to show is the creation of some new, useful protein with interesting functionality.

 

In my opinion, a more clear example is retroviral DNA in our genome (which a good, competent creator should not put there), and its similarity to other primate DNA (now we get a deceptive creator). Also, proof that the DNA is retroviral: a retrovirus has been reconstructed from the sequence.

[pioneer]

Doesn't that show a cause and effect relationship with respect to evolution, i.e, genetic movement toward a goal? If evolution was not goal orientated, the effect we see could also appear before the apparent cause. A previous random mutation, could just so happen to work out for the bacteria later in the future, when human begin to use antibiotics.

 

The first is like the wrecking ball swinging, so I duck; cause and effect. The second is my shoe becomes randomly untied. As I bend over to tie it, the wrecking ball misses me.

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I tend to think that evolution is driven by environmental potentials, which in the case of bacteria are the new medications we add to their environment. The goal of life can become set by the environmental potential, with continued life needing a specific range of change.

 

For example, I predict that all desert life has the ability to retain water in an efficient way. This commonality across the entire spectrum of life in the desert does not mean a common ancestor developed this ability and split into plants, animals and bugs. What it means is a common goal that could have been set at any time in evolution. The odds of thousands of life forms all having their shoes randomly untie, at the time, then all ducking at the same time, makes less sense, than all desert life seeing the same potential and needing to adapt on its own. They all duck in their own time.

 

When I lived in northern florida, they had trees the locals called "live oaks". This type of oak tree, only loses about half its leaves during the winter, with the remainder staying green. Normally oaks lose all their leaves in the winter. These oak tress may be adapting to the subtropical climate, but are still retaining some of their former adaptation.