Researchers document rapid, dramatic 'reverse evolution' in the threespine
stickleback fish

[moderator's note: There's a pretty good comparison pair of photos
in one of our daily papers if you want to look; here's the link:

http://seattlepi.nwsource.com/local/363263_oddfish16.html

Enjoy. - JAH]

Evolution is supposed to inch forward over eons, but sometimes, at least in
the case of a little fish called the threespine stickleback, the process can
go in relative warp-speed reverse, according to a study led by researchers
at Fred Hutchinson Cancer Research Center and published online ahead of
print in the May 20 issue of Current Biology (Cell Press).

"There are not many documented examples of reverse evolution in nature,"
said senior author Catherine "Katie" Peichel, Ph.D., "but perhaps that's
just because people haven't really looked."

This might be a good example of histone-coded environmental influences (or,
IOW, of environmental effects on the epigenome).
"Robert Karl Stonjek" bigpond.net.au> wrote in message
news:g0khkc$5os$1@darwin.ediacara.org...

(snipped)

This again fits my selection pressure model

The greater the selection pressure (directional or diversifying
selection)
the greater the speed of evolution in the area of selection pressure
And
the lower the seledtion pressure (stabilizing selection)
the lower the speed of evolution in the area of selection pressure.

Tom Hendricks att.net> wrote in
news:g0nk4a$1p7e$1@darwin.ediacara.org:

Tom,

"Robert Karl Stonjek" bigpond.net.au> wrote in message
news:g0khkc$5os$1@darwin.ediacara.org...

Journalists love to put a hook in their fish stories to help them catch
jaded readers.

The term "reverse evolution" kind of sounds like "evolution in reverse",
or "devolution". But of course there is no such thing happening in this
example. It's all just straightforward "evolution".

The same phenomenon has been documented in other cases. Jonathan
Weiner's _The Beak of the Finch_ gives a number of examples, including
variation in finch beak size with wet/dry conditions in the Galapagos,
and variation in guppy coloring with the presence of predators in
streams. In these cases, characters which have largely disappeared
from a population under one set of conditions come back under
new conditions that are like those in an earlier population.

I presume that the original researchers were more careful with their
language.

Alan