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Re: Long time maintenance was KillieTalk Digest V3 #1383



"Ron @ FAR EAST" wrote:
snip...

> I'd like to maintain some species and knowing no degenerative effects from inbreeding will help.  Could someone shed some light here?

Despite popular mythology, there are no known defects caused just by
inbreeding. Defects can arise from mutation (rare), but are much more likely
due to a bad recessive gene becoming homozygous (same gene coming from both
parents) and suddenly appearing. That is likelier when inbreeding from a
small gene pool that carries the defect as more individuals will have it.

Inbreeding will make the recessive defect show up more quickly (as defective
offspring) giving rise to the myths that it was "caused" by inbreeding.
[That's known as the *post hoc, ergo propter hoc* logical fallacy. "After
this, therefore because of this..."]

Killies tend to come from restricted waters and are often highly inbred in
nature. As long as the bad genes had been selected out, naturally, they
generally do not carry any.

The dangers of "inbreeding" may be more of hybridization than anything else.
If less than perfectly fertile offspring result from a hybrid, an alien
female Aphyo. or Fp. (that looks just like all the rest) can wreak havoc
with a line. The more the hybrids are inbred, the less fertile they become,
until the strain is no longer capable of reproduction. I believe this has
happened with several popular "Commercial Import" strains. This, BTW, makes
"gang spawning" and outcrossing riskier than they might otherwise be.

Getting rid of unwanted recessive genes can be a real pain in any breeding
program. Unless survival of your fish is vital to retaining them in the
hobby, it is easier to just stop reproducing (and distributing) fish that
throw known defects. Otherwise, worry about inbreeding is probably much
overblown (often due to sociological forces).

Poor selection of initial breeding stock, and failure to cull negative
mutations, are usually a lot worse problems in most killifish species than
inbreeding ever is, IMHO.

Wright

-- 
Wright Huntley,  Fremont CA, USA,  510 494-8679     huntley1 at home_com

In retrospect it becomes clear that hindsight is definitely overrated.

              http://environmental.networkroom.com/
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