mcall at SUPERAJE.COM
Thu Nov 16 08:23:24 CST 2000
"Zdenìk Skála" wrote:
> From: Curtis Clark:
> > IMO there are only two legitimate positions: (1) Species are not actual
> > units of nature
> 2) Species are units of nature that originate
> > through a process or processes that we call speciation
If we believe in evolution, then it is clear that species evolved and are in
the process of becoming species. With those that have clearly passed the
demarcation point of the biological species definition, there is no problem. I
would hazzard a guess that that involves ca. 99% of sexually reproducing
species or those that have processes that are similar to but not identical to
sexual reproduction or mix sexual and asexual phases.
That leaves some 1% who are in an apparent process of transition. One has to
provide an arbitrary rule or rules to provide a cut-off point for these. Some
indeed may not "go all the way."
So most species comprise real units and one can hold discussions about them
that are based on the failure to exchange sufficient genes to disrupt their
characteristics and their adapatations to ecosystems, etc.
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