Line Breeding Cichlids

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All I have to say is this all sounds so much like purebred dog breeding. Genetic background = pedigree pappers. Also I thought of dogs when I saw "german bred" some of the best bred Rots and Boxers come out of Germany.

Talk with some Good dog breeders about how they try and make their breed stronger. many of our popular breeds of dogs are or have been effected by inbreeding.
As for trying to save the wild fish we first have to save the habbitat. You can let 100s of healthy fish back in to the willd but most will die if the habbitat is endanger. So if you are looking to save the wild population of fish then work on saveing the enviroment first.
 
I agree with Snowflake, this is no different then establishing lines of pedagrees for fish as is commonly done with dogs ect. Finding two fish with desireable trates and breeding to produce a specemin based on an ideal standard. Inbreeding, linebreeding and outcrossing are all used to achive the desired results and fix the type over several generations. Outcrossing is generally done to add new blood to a line that has been closely in/linebreed to limit defects that will become exagerated or more obvious over time as they are passed down the line along with the desireable trates. Inbreeding is used to fix trates within a line but passes or magnafies any defects within a line. In theory this is a good idea however without a central registry to handle the documentation it would be almost imposseble on a large scale. Anyway, that's my two cents on the matter.
 
Snowflake311;4132432; said:
As for trying to save the wild fish we first have to save the habbitat. You can let 100s of healthy fish back in to the willd but most will die if the habbitat is endanger. So if you are looking to save the wild population of fish then work on saveing the enviroment first.
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Very true but how much of this damage is irreversible. Should our efforts to save these habitats continue to fail, we would have at least preserved captive specimens.

Question is, how to best preserve these specimens without propagating unfit genes when there is no way to mimic natural selection.

I don't completely agree but it can be argued that extinction, even as a result of human influence, is a part of nature. Some species will adapt to our presence while others wont.

Either way, once nature has made it's choice, is it ethical for us to reintroduce captive bred fish into re-established ecosystems?

Is it a mistake to believe that by propagating a threatened or endangered species in captivity we are doing anything other than what suits us?
 
I never get the whole saving the habitat things.

When i see shows on nat geo, discovery etc. they are always talking about the importance of not interferring with natures ways.
Like, if a lion pup is about to die, and could easely prevent it, "they" don't as it would interfere with nature's intentions.

WE, the humans, guess what, are a part of nature, and the degrading of natural habitats are also part of natures intention, so why suddenly do you want to interfere now??

I really don't understand
 
"I never get the whole saving the habitat things"

Are you for real? We as humans are parasites on this earth we take and take and never give back. Yeah we are part of nature but the things we do are in NO WAY natrual. Cars are not natural Chemicals to kill pests is not natrual DDT is not natural. It nearly killed off our birds of pray. Drilling for oil is not natural and look at what a mess the gulf of Mex is in now because of it. The list goes on. Humans actions cause lots of damage on the world around us and we need to change our ways.
 
Ed - you're really asking the right questions here.

My interest in fish and aquariums has helped me appreciate how important it is to conserve / preserve natural habitats...and to realize that fish are perfectly adapted to the role that they play in their ecosystems. If their ecosystems change, then they're no longer perfectly adapted to their niche...and the fish will begin to evolve to suit the new conditions...or fail to evolve.

Fish that live in aquarium conditions quickly become morphologically (not genetically) different than wild fish. They eat different foods, cope with different stresses and experience different conditions. Even the most authentic biotope tanks can't reproduce nature. Fish that eat pellets have very different jaw structures than those that eat snails (or algae).

Although I keep, breed and distribute a variety of fish in the CARES program (and have registered them with the ACA), this program neither has the participation (80-odd people last time I checked) or the governance model to mimic formal zoo-based species conservation programs (not that those aren't flawed in their own ways as well). I support CARES because it's something and because it's heart is in the right place. But we're kidding ourselves if we think it's really going to re-populate the wild with captive fish....or even supply the aquarium hobby with the "rare fish" that people want / covet.

Most people keep aquarium fish for aesthetic reasons. Since like 200 AD man has been line breeding fish to suit his tastes. I think people over-emphasize the importance of injecting wild blood into captive lines of fish. When was the last time koi were outcrossed to wild carp...or fancy bettas to wild ones? It would reverse tens / hundreds of years of work. There are some seriously skilled people who have developed stable, quality lines of fancy fish...

I hope that peoples' interest in aquariums and fish inspires them to learn about and support efforts to conserve / preserve natural habitats. I'd really like to see fish clubs like the ACA serve as a "voice" for fish and their habitats in broader conservation organizations (WWF, Nature Conservancy, etc.). I for one am not ready to throw in the towel on conservation / preservation of habitats.

Matt

flowerpower;4132916; said:
Very true but how much of this damage is irreversible. Should our efforts to save these habitats continue to fail, we would have at least preserved captive specimens.

Question is, how to best preserve these specimens without propagating unfit genes when there is no way to mimic natural selection.

I don't completely agree but it can be argued that extinction, even as a result of human influence, is a part of nature. Some species will adapt to our presence while others wont.

Either way, once nature has made it's choice, is it ethical for us to reintroduce captive bred fish into re-established ecosystems?

Is it a mistake to believe that by propagating a threatened or endangered species in captivity we are doing anything other than what suits us?
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Just to comment on the outcross idea.

If you cross two "unrelated" aquarium strains, or one aquarium strain to a wild fish, it's possible to restore a lot of the "wild traits" in the progeny. However, it would be extremely difficult to maintain these wild traits by subsequent inbreeding.

Most sequenced multicellular organisms have about 25k-50k genes. Assume the numbers of genes in cichlids are in the same ballpark, it's not difficult to imagine that a particular aquarium strain may have a few hundred suboptimal alleles.

Let's assume

- a particular strain has 100 "bad" genes, all of which are recessive
- a wild strain has all good genes
- these genes segregate independently (definitely not true, but for the sake of simplicity)

When you cross them, all F1s would be heterozygous for these 100 genes. Phenotypically they would be "wild". So far so good.

But if you cross any two of the F1s together, an F2 individual would have 3/4 chance to inherit at least one good copy of a particular gene. Therefore, the possibility that an F2 individual would have at least one good copy of all these 100 genes is 3/46^100=3.2E-13. That's 0.32 in a trillion.

For F2 to be homozygous for all wild alleles for these 100 genes, the probability becomes 6.2E-61, or 0.62 in a trillion trillion trillion trillion trillion :)

If you think 100 bad genes is too excessive, let's consider 10. The probability of an F2 being homozygous for wild type for all 10 genes is 0.95 in a million. Still hopeless......

The bottom line is that by outcrossing you can temporarily fix the problem in F1. To maintain the wild type trains you will have to keep outcrossing every generation, which, by the way, is similar to what happens in the wild :)
 
The issue is that people who breed fish in captivity tend to select for fish that appeal to them (e.g. big, colorful, high bodied fish) when natural selection might favor medium sized, brownish, torpedo-shaped ones). It's impossible to know what Mother Nature favors.

Cichlid genetics are extremely plastic, which is why they are so variable and quick to evolve. Specific populations of a particular species are very narrow genetically but can still demonstrate remarkable diversity, especially in different environmental conditions. Specific populations of a species vary in minute, minute ways from other populations of the same species.

Lake Victoria was dry 15,000 years ago... a couple of species of cichlids evolved into hundreds in that time...some of them are now extinct...and different environmental conditions in the lake (cloudier water, etc.) are resulting in natural hybridization, different natural selection and new fish...

Matt
 
flowerpower;4131059; said:
Is it possible to correct the degraded genetics of heavily inbred fish by selective line-breeding?
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Trying to be less pedantic honestly, but thus wouldn't work. Line-breeding is defined as inbreeding to fix a certain trait. Ie ... The father has a certain trait you like, so you take a daughter that has the same trait and breed them so that most of the offspring would have that same trait.

Oversimplified, but that is short hand of how linebreeding works.

As mentioned, I believe you would have wanted outcrossing.
 
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