Here is a question from a very amateur aquarist:
First some background. It seems that in general fish raised in captivity
have dealt with inbreeding fairly well. Most common aquarium fish, at least
those that breed easily in aquaria (OK,my fish), have gone through rather
prolonged inbreeding and still seem to do fairly well. Thus, point number
one is that inbreeding does not necessarily mean inbreeding depression. In
fact, as Allen Templeton has proposed, inbreeding may even be beneficial by
purging recessive lethal genes, as long as fitness is not severely affected.
Point two, mentioned several times before, is that captive fish maintained
by hobbyists are unlikely to be released into the wild unless there are no
other options. My take on this is that it is not the responsibility of any
one aquarist to maintain the genetic variability of the species.
So (finally) this is my question: Why don't aquarists aim to generate a
large number of genetically isolated lines (say 10-20) for each species? The
goal of maintaining a single genetically isolated stock is much easier
achieved by an individual aquarist or club than the goal of preserving all
of the species diversity. If enough independent lines are maintained, most
of the genetic diversity in the original stock (which, hopefully,is not one
fish) can be maintained indefinitely, as long as the lines are NOT crossed.
The fish do not have to be inbred purposely, though inbreeding will increase
each generation. If the aquarists were ever called on to reintroduce the
species into the wild, the independent lines could be crossed to regenerate
much of the genetic diversity.
Comments?
Mark.
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Mark Bagley bagley at ansci.ucdavis.edu
Department of Animal Science
UC Davis
Davis CA 995616