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RE: A. striatum identification.
Dr. Turner,
You wrote, "...in fact, we use a special name, "sibling species' (different
from "sister species") when "good" species cannot readily be distinguished
morphologically."
Is this the same thing as "cryptic species"? Is "cryptic species" a term
that is properly applied to killifish?
Thanks,
mike
-----Original Message-----
From: Bruce J. Turner [mailto:fishgen at vt_edu]
Sent: Thursday, May 09, 2002 1:00 PM
To: killietalk at aka_org
Subject: Re: A. striatum identification.
Please let me add my plea to Wright's. If you didn't get it with a
locality designation, then don't use one, no matter how well you think you
may have "back idnetified" your stock, and even if this means your material
goes without a locality designation altogether. We already have enough
sources of potential confusion without adding to the mix.
In saying the above, I am also struck by the irony of how the "worm has
turned" over the years. When locality designations were first introduced
by Scheel and others who knew that many populations of bitaeniatum,
bivittatum, gardneri, etc. were chromosomally divergent and would likely
yield sterile hybrids if crossed, people often did not want to use them.
Dealers, in particular, would complain bitterly about the absence of common
names, and getting them to use a locality designation was all but
impossible, possibly because the practice was unfamiliar. Long time
breeders were almost equally reluctant. And then there were the arm chair
biologists who learned about "binomial nomenclature" in school and for some
reason thought that the use of a locality designation. impeached the purity
of the nomenclature... Nowadays locality designations are so widely used
that their absence seem to make people feel insecure... I suspect that the
use of locality designations by collectors and importers of Rift Lake
cichlids during the same period may have helped these gain acceptance among
killifish specialists too. Certainly, they helped with dealers---ours here
in the Blacksburg area are comfortable with "gardneri Akure," "gardneri
Misaje," etc.
One other note and at the risk of lecturing (which is what I do for a
living and into which mode I drop too readily): Chomosomally divergent and
intersterile populations of Aphyosmemion, Chromaphyosemion, Fundulopanchax,
etc. are likely validly considered distinct species (under the biological
species concept). Scheel was aware of this, and of the fact that many
biologsts would have given each chromosomally distinct form a different
name (i.e., described them as new species). He was reluctant to do this
because he wanted his species to be morphologically divergent as well, even
though that is NOT part of the biological species concept---in fact, we use
a special name, "sibling species' (different from "sister species") when
"good" species cannot readily be distinguished morphologically. Scheel's
views are evidently held also by his colleagues/successors like Wildekamp,
Huber,and Radda. When I was younger (and a bit more inclined to be
arrogant or dogmatic) I argued about this with Joergen at some length --
for I felt that his attitude was quite "retro" (or even reactionary). And,
as Joergen would be the first to admit, it does make the locality
designations (which are sometimes labels for distinct sibling species) very
important, and these are obviously easily lost or confused in the course of
subsequent exchanges, commerce, etc. For those who like history, it might
be fun to know that the arguments between Joergen and myself exactly
parallel a famous series of disagreements in evolutionary genetics between
A.H. Sturtevant and T. Dobzhanksy when sibling species of Drosophila, which
differed only in their chromosomes, were discovered in the
1930's---Sturtevant didn't want to name them because he feared that would
make life too difficult for the "museum man" (as he put it) who needed to
have species based on morphology; Dobzhansky disagreed, and ultimately
prevailed, which is why we have species today like D. simulans, D.
persimilis, D. similis, etc.
However, recently I have begun to realize that Scheel's practice is a
good interim measure. It enables us to keep stocks derived from different
populations separate and labelled a long time before we have had a chance
to assess the level of their actual chromosomal or genetic distinctiveness.
This fauna, by modern standards, is only superficially surveyed, and it
merits detailed work, and by this I mean effort beyond the "alpha" level---
population-by-population chromosomal, morphological, and general genetic
surveys. These are not, to my knowledge, now being done. In the future,
when someone emerges who devotes his/her career to doing this, some of our
different stocks will doubtless prove to be conspecific in the rigorous
sense, while other will likely need to be labeled as distinct species.
****************************************************************************
**
Bruce J. Turner
Assoc. Professor of Biology
VPISU, Blacksburg, VA 24061
(540)-231-7444
fishgen at vt_edu
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