Pond Boss Forums INTRO Questions & Observations inbread

Traditionally, inbreeding is used in stock breeding to reinforce desirable traits AND to eliminate undesirable ones. But you have to relentlessly cull bad traits when the genes are reinforced to get improvement. Where inbreeding is not combined with harsh culling (such as when a breed of dog gets "hot" and the puppy mills churn out all they can, or in royal families) we see the negative effects without noticing any improvements (obnoxious hyper poodles, labs with bad hips, and Bruce's horse (faced) picture).

In a pond with lots of competition, culls should do poorly and starve, get eaten, or reproduce poorly due to disadvantages in size or condition. We can hurt or help this process by removing the biggest and the best or culling the small and the weak.

Jack and coke sound like an Aa to me.

EWEST,

Any way to get more info on this question? I've always thought(perhaps incorrectly) fish are like cows in that you need to avoid sustained inbreeding. That's why I have always tried to rotate some "breeding" stock among my ponds...and also why I like to occasionally buy some fish, e.g. coppernose BG from a completely different source. Maybe that's a waste of time?

This is really hard for me to say...but Theo is correct on all counts.

The fact that competition will weed out inferior genes is completely true. Keep in mind however, that inferior genes in one pond or lake may be slightly different than what constitutes inferior in another pond, based on variances in water chemistry, prey type, etc. This is why it's so important to have at least a little variability in the original genetics. If you were to start with only two parents than the inferior gene is on the same allele of ALL progeny, so fish are competing with other inferiors. Competition doesn't work at all in that situation. Now if you have maybe three or four of both males and females and they "mix" well in the first spawn, then the defective genes are on different parts of the DNA strands depending on which parents you came from. Therefore, you have competitive pressure from some fish that are superior genetically. I'm no geneticist, but I suspect that just a few parents of each sex is enough to set competition into effect and eliminate inbreeding depression as a concern.

Theo's also right about inbreeding as a form of reinforcing some postive traits, but this is impossible to build into pond reproduction dynamics because you can't put effective pressure on defective individuals. You'd have to be able to examine every single progeny AND have the knowledge to know what constituted a good and a bad offspring. Not very practical when dealing with tens of thousands of offspring from a single parent.

BTW ewest,

Your biologist may have been trying to say something different but--Fish genetics DO work that way. ALL genetics work that way. That's actually the beauty of genetics. We are learning more and more about genetics over time, but fish genetics, cattle genetics, butterfly genetics, human gentics--IT'S ALL THE SAME.

Aa X Aa will always yield AA, Aa, Aa and aa.

My oldest daughter is 12 years old and she has already been caught classic Mendelian theory. Maybe what he was trying to say that new genes weren't necessary to add to an already healthy pond, but, as I stated before, I wouldn't start with two crappie.

Bruce , ML & Theo :

Thank each of you for the info ,ideas and response. I agree with you. From what I thought and as you have confirmed genitics does work that way. I belived that at the time , even in view of the biologist's answer and I still think so today. I think , as Bruce noted ,that either he misunderstood the question or knew somthing that I didn't relative to the population or condition of the pond. Bruce I think you are exactly right, he thought that in a healthy but under feed pond genetics were not the problem and did not need addressing. It was his way of saying ,and I agree , deal with water quality and forage base first and foremost. I did and added new genes anyway. ML for me those cows { fish} had been in the same pasture together for to long.

To me genetics is to a large part dealing with probability and statistical analysis. You may get lucky one time but in the end the rules of nature will control. I don't want to take that bet in my ponds.

That leaves me with the questions of how many parents, how big of a population and for how long. If you have any thoughts ,data or suggested readings on these I would be interested. I know that The American Fisheries Society has a book on population genetics that would probably be a good place to start.

Thanks for your efforts on this thread. ewest

OK all, don’t want to go down another rat hole, however... :rolleyes:

If I understand the prior posts on how undesirable genes/inbreeding works, then, the opposite must be true: We can (and should) be able to proactively manage for desirable genes. In other animal breeding programs we typically would select only superior breeders and encourage those desirable traits while culling and/or denying the undesirables to breed.

And if that’s true, wouldn’t we LIMIT the breeding stock rather than expand it? Or at least greatly control it for only superior additional genes added to the breeding program?

Too much inbreeding gets you this.That's a hell of a fish under the umbrella.

http://hometown.aol.com/jlygas/images/bubba\'s%20baby.bmp

Just Joe, what a great picture! Is this what they mean when they say you know you are a redneck when your family tree only has one branch?

Almost all commercially bred domestic animals are extremely inbred. Chickens are almost identical. This can be done by sever culling of any animal with any kind of problem. The remaining animals are then selected for whatever characteristic is wanted. There is a down side to all of this. There is almost no genetic flexibility to change in the remaining animals. Scientists are becoming more concerned about this. Rare breeds of domestic plants and animals are starting to be preserved just to have the genetic flexibility to change if it is ever needed.

its when your family tree doesnt branch?

Norm said:

This is true as I know it.

However, did you see the study where they took pure bred chickens , as identical as they could get, and began selecting for two strains (large and small). There is a very limited amount of genetic diversity available, so the two strains don't separate by much. At first. After ten generations, they start getting more size variation in each strain to reinforce. I believe this experiment has run for 30-40 generations; the "smalls" are approaching Cornish Game Hen size and the "larges" are super-Chickens, getting close to the upper size limit of what Chicken physiology is thought to be able to support.

The bottom line is (to me) there is a lot we still don't understand about genetics. For fish ponds, I believe in covering all the bases, safely. 1) Start with a fairly diverse gene pool. I think fish from most/all hatcheries are probably OK in this respect. 2) Support the culling of reinforced undesirables where possible through good management practices (release the large fish to breed, harvest the small). 3) If concerned about genetic diversity after (many?) years, add more stock intelligently (as noted above, it's not worth adding genetic diversity if the new fish make the rest sick).

Bruce: A Dentist should have access to anesthesia when forced to perform painful acts. If not, there's always more Jack.

I'm with Theo on his "basics of pond genetics" recommendations.

Culling fish on an individual basis to manipulate gene quality is a daunting task. Probably impractical in almost every respect. I do think that it is easier to damage the genetics than it is to help them. Catching and keeping all large reproductive male bluegill off their nests is a good example on down-pressure on genetic quality. Why risk it? It's too easy to release these fish and pressure (harvest) the smaller individuals.

This is a whole new thread but I'm watching two thousand age-1 bluegill grow in two different small ponds of mine. These fish were all progeny of BIG, healthy parent fish that happened to like artificial feed. I'll protect and breed the best growers next fall. I'll keep everybody informed as to the progress of this craziness.

The whitetail deer growers that I've talked to and read about are tackling genetics. However, they still aren't sure what side of the tree is the most important, if either or both. Using the superbuck as a sire is obvious. However, they still aren't sure about the role of the doe.

Theo, you are so very right. There's so much we don't know about genetics. One of the most incredible things is that genetics are often not controlled by the genes! It now appears that messenger RNA controls much of the expression of the genes.

In case any one thinks that this is technical stuff way beyond any normal persons thinking, it is not. Pure bred breeders of almost any sort of animal know and use this stuff all the time. They can tell you about line breeding, out-crossing, dominants, recessives, sex-linked and much much more. A $2,000 dog becomes a give-a-way if you don't know this stuff.

Norm, What is messenger RNA?

Dave, we know that the genetic code is made up of DNA. DNA is the double helix that zips apart to make new copies of itself. DNA is just information. Somehow this information must be used to make proteins. This is where messenger RNA comes in. RNA is a single strand of information compared to the double strand of DNA.

mRNA picks and chooses the information from the DNA that will be expressed in the form of a protein. It now appears that the process of picking and choosing which information will be expressed in the form of a protein is at least as important as is the DNA code for the protein itself.

Thanks, Norm. Just think about how dangerous Bruce could be with a lab and a big budget.