RE: NANFA-L-- Re: the aquarium hobby as conservator of

Christopher Gutmann (cgutmann-in-dupageforest.com)
Fri, 12 May 2006 14:16:04 -0500

The problem with genetic drift is that it can result the reduction of
alleles and loss of variability. If this happens, then a species would
be less able to "adapt." That is why there is an emphasis on avoiding
genetic drift in captive propagation projects. Genetic drift in captive
breeding programs does not increase the genetic arsenal / variability of
a species. The smaller the gene pool, the more likely genetic drift
will occur. Ideally, the purpose of a captive breeding project of a
declining species is to maintain its complete genetic arsenal while
attempting to increase the abundance of that species. This, of course,
is easier said than done. Many zoos involved in species survival plans
employ individuals whose sole purpose is to track and plan pedigrees
with other zoos in an effort to minimize the loss of genetic diversity
and attempt to prevent genetic drift in captive breeding programs.

Chris Gutmann
Salt Creek, IL

-----Original Message-----
From: owner-nanfa-l-in-nanfa.org [owner-nanfa-l-in-nanfa.org] On Behalf
Of Jerry Baker
Sent: Friday, May 12, 2006 12:34 PM
To: nanfa-l-in-nanfa.org
Subject: Re: NANFA-L-- Re: the aquarium hobby as conservator of
populations-in-risk

Moontanman-in-aol.com wrote:
> I have to disagree, release a large number of domestic goldfish into
the
> wild, in a pond or even a stream. In a very few generations you will
have wild
> type goldfish again. I've seen it happen in even small ponds. animals
are often
> genetically more plastic than we give them credit for.

Indeed. The whole argument that captivity induces genetic drift, and
therefor bad, is a tautology. Of course there is genetic drift because
that's what happens when one population of a species is separated from
another. It might not have anything to do with captivity and just be the

process of natural evolution continuing along slightly different courses

in isolated populations. Sure, the conditions of captivity can influence

the evolutionary path, but that shouldn't matter much as long as the
animals remain able to survive in their natural environment. Without
constantly providing for genetic exchange between two populations held
in isolation, of course they're going to drift. Keep them separated long

enough and they may evolve into separate species. That's the way it
works.

It seems to me that trying to keep a population of some threatened or
endangered creature genetically stable is as foolish as was the old way
that the National Park Service used to try and prevent any changes in
the forests. After a while the exclusion of fire and other disturbances
was destroying the very forests they thought they were protecting. I
don't think it would be helpful to actively prevent a species from
experiencing the genetic drift that might allow it to adapt and survive.
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