Re: [Killietalk] Scott Lobbstael's question

["Roger L. Sieloff" <isodox at sbcglobal_net>]

Frankly, I see nothing wrong with crossing fish from different breeders as
long as they are the same population. Of course I understand the arguement
that if the gene pool is small then outcrossing might be a waste of effort.
However, a recient thread seemed to suggest many supposedly "pure" strains
are none the less highly variable. Fp. gardneri was the example. My
strongest arguement for keeping the gene pool as open as possible comes from
the AKA (American Kennel Association). These pedigree dog breeders learned
the hard way that excessive inbreeding leads to a whole range of recessive
genetic defects. Now the AKA is trying to be a bit more felxable reguarding
breed standards.

Granted, fish can take a lot more genetic abuse than dogs can, but I'm sure
even killies have a limit. I've always concidered "belly sliders" a genetic
defect rather than an environmental one. Of course these fish never breed,
but their "normal" siblings may still carry a recessive, defective gene.
This then is passed on to the next generation and manifests itself in any
fish with a pair of these defective genes. One other law of genetics is a
constantly inbreeding population aquires perfectly matched genes over time.
Therefore, there is a 50% probability the recessive gene will dominate. The
consequence of this is that all the fry are going to be belly sliders, and
at this point the strain will be ruined.

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