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Re: Selective Extinction



Dann Pigdon wrote:

> Given the rapid reproduction rate of micro-organisms I suspect that
> they have the ability to evolve faster than macro-organisms.
> I wonder why people don't study evolution in microbes rather than
> creatures like anole lizards? It probably wouldn't take 30 years to
> show results. 
They do indeed, as someone has already mentioned.  The problem is that 
bacteria don't reproduce sexually, at least in the same sense as e.g. 
mammals.  However, they can evolve very fast, as you suggest.  One of the 
fun things they do is to spread virulence factors (antibiotic resistance 
factors, immunosuppressors, etc.) by means of plasmids, small circular 
lengths of DNA that might once have been bacterial viruses ("phages").  
These *do* spread to other types of bacteria.  In any case, the bottom 
line is that the genetics of bacteria are a lot different from 
vertebrates, making them less appropriate models for evolutionary 
studies.  Slime molds, _Dictostelium_ and the like, are eukaryotes, have 
better genetics and (I think) an optional sexual mode of reproduction and 
are coming into favor as a model.  But I was never a slime mold man and 
don't know much about them.

  --Toby White