Re: spawning?

[IDMiamiBob@aol.com]

Ed Pon writes:

> Andrew Faust wrote:
>  I have a question more about general genetics than about the 'parenting
>  >gene': have any of you observed occurrences of "unwanted" recessive 
traits?
>  I asked as very similar question at the local Killifish club some years 
ago 
>  and the answer from people at the meeting was that many people have kept 
>  strains going for many generations and found no problems with the 
offspring.
>  
If a recessive "undesireable gene is present in the original pair, it will 
show within a few generations of inbreeding.  If it has not shown after that 
time, it's a safe bet it's not there.  After that, it would require a genuine 
mutation to cause a problem, and that genuine mutation would have to occur in 
the repoductive organs of the fish.  The vast majority of such mutations lead 
to fish that don't survive to reproduce.  The percentage of mutations that 
occur and produce viable fish in the next generation is miniscule.  
Split-tail bettas are an example.  If you cross a split-tail with a 
normal-tail, you will get a 50/50 mix of normal and split-tails.  Breed two 
split-tails together, and you get 25% normal, 50% split-tails and 25% that 
never hatch.  The ones with two split-tail genes can't survive.

Similar things occur with the vast majority of mutations.  They are fatal 
either recessively, domimantly, or co-dominantly.  On the other hand, most of 
the ugly things goldfish fanciers keep in ther tanks and ponds are the result 
of mutations that in the wild would never survive.

There are a number of genetic mutations in the hobby that affect color or 
finnage.  But we tend to call those "sports" rather than mutations.

Bob Dixon


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