>To continue, such an extrapolation is unwarranted because of the simple fact
>that changes observed in STE studies and bacterial resistance are
>_reversible_. While finch's beaks become more robust in times of drought
>when seeds have tougher shells, they revert to the more slender shape when
>climate returns to normal and seed shells less hard to crack. Such
>reversibility disqualifies STE from serving as the mechanism of DWM, or at
>least raises serious questions about it. The statement would be more
>forthright and therefore improved if it acknowledged this.
My comments:
I don't see how changes in the finchs' beaks indicate that natural
selection isn't a mechanism for descent with modification. During droughts
the finches with larger beaks fare better than the smaller-beaked variety
and so become more common. When the drought ends, the larger-beaked
finches don't fare any better than the small-beaked variety (in other words
the pressure that caused them to be favored by natural selection is
removed). The small-beaked birds can again get enough to eat to be able to
reproduce, and so their population increases. In other words, the
population of the large-beaked birds increases relative to the population
of the small-beaked birds when conditions favor large beaks, and it doesn't
when those conditions no longer exist. That seems to me to be a pretty
good example of natural selection resulting in descent with modification
(evolution).
Did I correctly understand the point you were trying to make or did I miss
something?
John
This archive was generated by hypermail 2b29 : Sat Dec 08 2001 - 13:47:02 EST