From: "Rich Gauszka" 


"John Beckett"  wrote
in message news:nrd3n1llliq0ei7lk2iv54o0fk4omr937p{at}4ax.com...
> "Rich Gauszka"  wrote in message
> news::
>> Microevolution involves small-scale genetic changes in a species over
>> time.
>> The classic example is a color change undergone by British pepper moths
>> in
>> response to changing levels of air pollution. The acquisition of
>> antibiotic
>> resistance by bacteria and the trend towards tusk-less elephants in
>> Africa
>> are also examples of microevolution at work.
>
> Interesting piece, but the above para caught my eye. I see by putting
> "define:microevolution" into Google that the above really
are examples of
> microevolution.
>
> However, I recall reading an explanation that the colour changes of the
> British moths were probably not what we traditionally regard as
> "evolution", in that the ability for that moth to be black
or white was
> probably already present in its genes. It was only a small control
> function that needed to be activated to decide what was currently the best
> colour for survival.
>
> By contrast, I believe that antibiotic resistance of bacteria really is
> evolution (usually). Random changes to the genes of some bacteria occur,
> and some of those are slightly helpful for surviving mild doses of an
> antibiotic. Similar changes accumulate, and you end up with a truly new
> kind of life.
>
> Any comments?
>
> John
>
The Berkely link cites 3 examples: size of the sparrow, coping with global
warming,  and building resistence ( your bacteria example )

http://evolution.berkeley.edu/evosite/evo101/IVB1aExamples.shtml

Microevolution is defined as a change in gene frequency in a population.
Because of the short timescale of this sort of evolutionary change, we can
often directly observe it happening. We have observed numerous cases of
natural selection in the wild, as exemplified by the three shown here.

artificial selection in the lab
http://evolution.berkeley.edu/evosite/evo101/IVB1bInthelab.shtml

For thousands of years, humans have been influencing evolution, through
changes we have caused in the environment-and through artificial selection
in the domestication of plants and animals. In many cases, scientists have
carefully documented evolution through artificial selection in the lab.

John Endler performed experiments in microevolution, allowing artificial
selection to manipulate the spots on guppies1. Guppy spots are largely
genetically controlled. Spots that help the guppy blend in with its
surroundings protect it from predation-but spots that make it stand out
help it attract mates. Endler set up similar populations of guppies in
artificial ponds in the laboratory. Ponds varied in the coarseness of
gravel on the bottom and all ponds had predators. Below is a simplified
representation of Endler's experiment.

..........

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