mcall at SUPERAJE.COM
Wed Sep 22 17:12:55 CDT 1999
Ken Kinman wrote:
> I have to agree with Richard (Jensen). Raising Homo sapiens to a higher
> taxon in the "Mars" example makes no sense, and to me this is an example of
> the "semantics" I referred to when I started this thread on "cladism's
> greatest weakness".
Reproductive isollation sensu Ernst Mayr and followers of the biological species
concept has never included geographic isolation (alone) as a case, whether
separated by planetary, continental or other spaces. Reproductive isolation
instead refers to an intrinsic or genetic barrier that prevents two populations
from producing significant numbers of fertile offspring. That can include
behavioral, mating time, morphological, sterility and other kinds of mechanims.
Morphological, genetic and other evidence may be used to adduce the existence of
The reproductive isolation criterior for attainment of species-level status is
most easily evaluated when the populations are sympatric or contiguous. When
the two populations are allopatric, other criteria must be brought to play.
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