JEAN MICHEL MAES
jmmaes at IBW.COM.NI
Tue Oct 12 07:26:41 CDT 1999
Dear Ken Kinman,
Thanks a lot for the information. Semi-species is a concept very useful to
explain evolution, because it is something in process. I have seen once
also in a publication on scarab beetles (I did not remember the reference)
the definition of something called CLINE, which is the same, but involving
a serial of populations. Through Africa, from Senegal to Tanzania, you have
several populations. Each contiguous populations are little different, as
subspecies; but the populations of Senegal and the populations of Tanzania
are totally different, as two different species. So the interpretation are
two species with intermediates or one species with many subspecies. Anyway
we can give the interpretation of a process of speciation, perhaps withing
some more time we will have there a lot of different species...
In the case of human species. There is only one species. Can we consider as
subspecies the natural populations of different regions ?
At 06:49 PM 11/10/99 PDT, you wrote:
> I don't recall the exact definition of a semi-species, but is a
>basically a species caught in the process of becoming two separate species,
>but not enough divergence has occurred for "isolating mechanisms" (my
>apologies to Ernst Mayr for using that phrase) to be perfected.
> I believe Les Kaufman (here on Taxacom if I recall correctly) once
>referred to this as "webbing at the node", which is a pretty good way to get
>the idea across how "messy" speciation can be, being the continuous process
>that it is (except perhaps for allopolyploidy).
> Semi-species are probably usually formed when two "incipient species"
>come back into contact before speciation is complete, and massive secondary
>hybridization occurs where they come together. Presumably a lot of this
>kind of thing happens at the end of Ice Ages, but retreating ice is just one
>of many potential scenarios that can trigger the genetic introgression by
>which semi-species can be recognized. Perhaps others could explain this
>more fully than I.
> --------Ken Kinman
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Asociacion Nicaraguense de Entomologia
AP 527 - Leon
jmmaes at ibw.com.ni
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