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From: alien@cpoint.UUCP (Alien Wells)
Newsgroups: alt.aquaria,news.groups
Subject: Re: a bunch of things
Keywords: stuff
Message-ID: <2720@cpoint.UUCP>
Date: 26 Oct 89 14:09:26 GMT
References: <21387@gryphon.COM>
Reply-To: alien@cpoint.UUCP (Alien Wells)
Organization: Clearpoint Research Corp., Hopkinton Mass.
Lines: 78

In article <21387@gryphon.COM> richard@gryphon.COM (Richard Sexton) writes:
>Speaking of OCC, there is a new fish in that group. The
>Germans ave described it as Roloffia huwaldi, but
>people more interested in the science and less interested
>in keeping Mr. Huwalds name on the fish consider it
>to be a subpecies of OCC, viewing it as intermediate
>between ocidentalis and toddi. This is backed up 
>somewhat by the fact that second and third generation
>crosses with OCC and TOD are fertile. To their mind there should
>be  Aphyosemion (Chroaphyosemion) occidentalis occidentalis,
>A. occidentalis toddi and A. ocidentalis huwaldi. Huwaldi
>is a blueish fish, more like a blue occidentalis than
>the somewhat stockier toddi. It is a new introduction;
>the Germans just collected it last summer, and it should
>be available (probably through the new and rare species
>committee of the AKA) sometime next year.

I am glad to see that you at least said backed up 'somewhat'.  The taxonomy
of killies has always bothered me.

To establish a new species, the standard criterion is the infertility of 
crosses between the population in question and all other species.  This is
generally a matter of genetic incompatibility.

Allow me to spend a moment describing the mating behaviour of killies for
those who might not be familiar.  After appropriate courting rituals, the
male killie physically grabs the female with the dorsal and anal fins.  The
anal fin of the male and the anal fin of the female are joined to form a 
tube which the eggs and sperm are simultaneously deposited into.  The 
fertilization happens, then the fertilized eggs are let loose into the 
environment, generally either into the bottom mud or into foliage (breeders
generally use peat moss or a 'mop').  

The typical environment for killies is very acidic - and will kill any sperm 
that comes in contact with it before fertilization.  The cross 'species' 
infertility of killies is generally caused by the failure of the anal fins
to match into a perfect tube, allowing the acidic environment to intrude
and kill off the sperm before fertilization.  Thus, it is a physical,
dimensional issue - not a genetic one.  Experiments have shown that most
'species' of killies CAN be cross bred if they are stipped and the eggs are
artificially inseminated.  Furthermore, many 'species' that are infertile
in the wild can be sucessfully cross-bred if they are put in an appropriate,
non-acidic environment (although getting them to want to breed in that 
environment can be difficult).

Many people have speculated that the physical, as opposed to genetic, nature
of the cross-infertility can help explain the amazing diversity of killifish
species.  A very small mutation that changes the size, shape, or position of
the anal fin - even by a small amount - can lead to a new population that 
cannot breed back into the parent population.  However, this also causes 
some very bizarre possibilities.  There is a case (I believe it is in the
Andes) where populations of killies were taken at intervals all around a
mountain.  Every adjacent pair of killies could cross-breed.  Pairs from 
across the mountain could not.  Basically, there was a gradual shift of 
the geometry of the anal fins which would eventually become large enough
to prevent fertile crossing.

So, what am I trying to say?  (I apologize for my long-windedness.)  Only that
I smile whenever I hear the furious debates about the taxonomy of killifish
(the debates about what to name new newsgroups are tame by comparison).  I
may be branding myself heretic, but I feel that the current way of classifying
killifish is fundamentally flawed.  I also feel that any correction of the
situation is going to be a major research project.  My feeling is that the
taxonomy of killifish should be extended from 2 levels to 3, with the second
level being genetic infertility and the third being physical infertility.  I'm
quite aware, however, that this is a rather controversial proposal in what is
a rather conservative field (ie: taxonomy).

In the mean time, is is very important for breeders to continue what they are
doing, which is coming up with some method of classification and keeping the
populations pure.  Regardless of how you feel about the taxonomy, it is 
important to make every reasonable attempt to keep the strains true to what
they are in nature.
-- 
--------|	You've got the political savvy
Alien   |		of a hangnail.
--------|   					- John Meneghini
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