RE: Further thoughts on SMP

["Griffiths, Richard" <rgriffit@visa.com>]

>Richard wrote:
>
>>>Sure, there are anecdotes like this, but this was pure chance.  There is no
>>>evidence that such a situation would have the same result with fish or any
>>>other organism.  In fact, I can think of other anecdotes from the aquarium
>>>hobby in which the abililty to breed certain aquarium strains became
>>>increasingly difficult from generation to generation, most likely due to
>>>effects of inbreeding.  
>>
>>While I appreciate your dialog, your third sentence above is very
>>misleading and highly inaccurate when you consider the selective
>>genetics of the guppy, swordtail, platy, betta, and molly. And I
>>disagree with it based on genetic and personal experience.
>
>I think you mean my second sentence.  I can see how this statement can be
>easily contradicted by the evidence you present.  However, what I meant to
>say (forgive me for not being clear) is that there is no _guarantee_ that
>line breeding will be "beneficial" or benign for any given species.  
With that, I agree, in part. Proper (researched, worked on, and
achievable end results) breedings from a 'good' originating stock (best
of the breed available) will more likely provide those qualities
desired. And true, even with really good work, there is no guarantee
since we don't know the genetics of the fish we have. 

>For example, many killifish keepers have been complaining about low fecundity
>in some strains of Aphyosemion australe gold (the orange lyretail), a morph
>that has been line bred for quite a long time (perhaps 30 years or more).
>This fish was considered extremely easy to breed in the past.
>
>>While fish in streams, rivers, ponds, and lakes have the ability to
>>travel, most remain relatively in the same general area, thereby
>>reducing their genetic diversity  by not traveling to somewhere else in
>>the area, i.e., 20 miles downstream. If collections are done along a
>>stretch of a river for the same species, there is some genetic drift as
>>isolated pockets do develop--that's what happens in the hobby as well.
>>But where do you draw the line of what is a species, what is acceptable
>>for maintenance as opposed to maintenance of every conceivable 'genetic
>>drift' combination you might find? I don't have an answer to that.
>
>Correct, many populations of a species may be quite isolated from the
>others.  And, genetic drift may occur, but will only be significant if a
>population is relatively small.  However, when there are several different
>populations of the same species, separate enough to drift genetically from
>one another, the occasional migrant between populations can be extremely
>important for both within-population and total-species genetic diversity.
>In such a species, this rare immigrant could be a large factor in
>preventing increased homozygosity and associated inbreeding depression.
>While this statement is based mostly on theoretical results (including my
>own), we do not have enough empirical data to say whether or not this
>effect is important in living organisms (it would be a big job to measure
>migration rates between populations of Apistos!).  So I would say that it's
>best to be on the safe side, and attempt to preserve as much genetic
>diversity as possible.  Of course, not knowing the "natural" rates of
>migration between populations makes it impossible to suggest a satisfactory
>rate of crossing between aquarium populations (if any such crossing should
>be carried out at all).
Amen.
>
>As to your last question, I would say that if we're interested in
>preserving a species in the aquarium hobby as it is in the wild, we should
>try to keep representative populations from as large a portion of a
>species' range as possible.  "Where to draw the line," while not
>straightforward, shouldn't be too difficult a decision.  However, if one of
>the goals of a SMP is to preserve a good portion of a species' total
>genetic diversity, I would suggest the following program:  Keep populations
>of a species separate in aquariums, but attempt to keep as much genetic
>diversity within populations as possible by not culling too severely and
>infusing the aquarium population with "new blood" from the wild populations
>whenever possible (as Steve originally suggested).  It would even be
>possible (although a logistical challenge) to keep track of an "effective
>aquarium population size" for each population, if one had lots of free time
>on his hands.
I would agree, except with the current brand of 'splitters' among the
ichthyiological community make many more species from what might be
considered minor variations, we would then be continuing to perhaps
isolate populations of a species, and call them species, thereby
limiting it's potential for true diversity by breeding with the 'other
species' that varies little, and perhaps not significantly from the
'species' in question. And while a green swordtail from Mexico, may just
be a Xiphophorus helleri, the respective populations from the Rio Ameca,
Rio Ayotec, etc. etc., are different than the X. helleri from Belize, or
Guatemala, and each other. And now share the unhappy position of having
introduced platies and domesticated swordtails invading their
environments. Oh what tangled web that would weave if trying to 'infuse'
populations. Fortunately with cichlids, that doesn't happen much, unless
Tilapia are able to breed with Apisto's in SA...

And if you could infuse from the wild. In some cases of fish, there are
restriction problems, extinction, and locale issue. But in any case,
keeping the stock as pure as one can, and as little 'infused' as
possible from unknown, or questionable sources, is a noble goal.

>
>>fish in the future. The problem is, of course, each individual's
>>interest, limited resources, and perception of the need. It would only
>
>Very true.  I would bet that most aquarists, while generally supportive of
>conservation efforts, mostly just want beautiful fish for their aquariums,
>and aren't too concerned with their fish's genetic background.  Now that I
>think about it, my comment above about "effective aquarium population size"
>seems like sheer lunacy. ;)
I differentiate between hobbyist--the general population of people who
have fish, and aquarist--that person who breeds fish, learns about them,
and contributes to the overall knowledge base of the 'hobby'.
>
>Julio wrote:
>
>>I think the SMP can accommodate both. Categories that separate "species",
>>"aquarium strains", and "populations" will play an important role here. The
>>first two categories will deal with the hobby while the "population"
>>category can cover conservation of wild populations. 
>
>I agree wholeheartedly.  So long as the members of a SMP keep things
>separate, they will be carrying out an interesting experiment no matter
>what they do.  Then, using their results, they can refine their program.
Yep

Richard
>
>
>
>-------------------------------------------------------------------------
>