Breeding True

Discussion in 'Breeding' started by Vis, Jan 7, 2010.

  1. Vis

    Vis Gerhard

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    Hi

    If I have a female EVE and male Adam that have a fry Piet.

    What is the best and simplest way to get fry that looks like Piet and breed true?

    Rgards

    A diagram would be nice:p
     
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  3. Zoom

    Zoom Retired Moderator

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    Huh???
     
  4. Dirk

    Dirk Dwarf Catfish

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    Hey Vis,

    Is this a Friday evening dronk verdriet, or are you asking us if you cross your German shepherd with your Dachshund how long it is going to take the offspring to look like a German shepherd? Well, from the genetics point of view, you must cross the first generation offspring back to the parent that you want it to look like. In other words, you would cross the female offspring of your German Shepherd cross Dachshund back to its father and the offspring would then be 3/4 German shepherd. You could then again cross the offspring back to the father so that you get to 7/8 German shepherd and so on.

    I hope this is what you mean.

    Kind regards,

    Dirk
     
  5. Big G

    Big G Apisto Nutz!!!

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    Sorry Prof, just to bring this down to incestuous level, are you saying that you cross the Daughter with the Dad, and then the Resultant Daughter with the dad again???

    I've always struggled to understand the complexities of Genetics! Easy to get lost somewhere along the way, especially after a 'Friday evening dronk verdriet'!!

    Cheers
    Big G!
     
  6. OP
    Vis

    Vis Gerhard

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    Dronk verdriet? Maybe if I drank.

    Zoom the thing I wanted to know is: If you cross a green guppy with a yellow guppy and get a blue guppy. How do I ensure that I get more blue guppies that breed only blue guppies like it. Do not want to breed the blue guppy with another female and get a blue guppy with a pink head.

    Prof so your saying that it comes down to inbreeding.
     
    Last edited: Jan 9, 2010
  7. Dirk

    Dirk Dwarf Catfish

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    OK Vis,

    Alle grappies op 'n stokkie.

    Ok, I thought that your question would have been related to guppies.

    It is exactly as I explained. If you get this blue guppy from a green guppy crossed with a yellow guppy, then you would cross him back to his mother. The reasoning here is that you are trying to breed him with something that has an many of his genes as possible and not just some other guppy that has other color genes. The offspring of this son mother cross then have half of the genes of the son (the blue guppy) in other words they have the chance of looking similar to their dad, the blue guppy.

    You then raise the young, but separate the males from the females as soon as you can sex them to stop them from mating with their brothers (you could also let the males grow on to see if they have colors that look similar to their dad, in other words the blue guppy, and this tells you if your breeding is being successful, but you do not use them for breeding). You then put the daughters in with their dad so that he mates with them. The resultant offspring will then already contain 3/4 of the genes of the father. You again raise the young, and again separate males from the females as soon as you can sex them. Again put the females in with the blue guppy, in other words their grandfather and their father (that is if he has not burnt out yet....) so that he mates with them, the resultant offspring is 7/8 blue guppy. By this time the male offspring should start looking like the original blue guppy, and you could also start breeding from them by mating them with their sisters.

    This concept is called line breeding in genetics, and it is used to "fix a strain", by that I mean that all the guppies of that strain look similar to one another. This process does involve considerable inbreeding, which we always assume is negative, but in some animals and plants it is not negative. I could explain why this is the case, but that would be another separate lecture again......

    Hope this helps.

    Kind regards,

    Dirk
     
  8. Big G

    Big G Apisto Nutz!!!

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    Ok Prof, One further question, suppose you have bred a pair (X + Y), and you get the blue offspring female (Z), which you then mate with the original male (X), and get more blue offspring... If one of these offspring was a blue male (S), would you mate that male with the first offspring Female (Z), or would you mate him to the Original female (Y)??

    How far can you go before the line is too inbred?? How do you introduce new blood without loosing the blue?

    Sorry for hijacking your thread Vis!

    Cheers
    Big G!

    Sorry Prof, Missed the last bit about then breeding them with their sisters!

    Cheers
    Big G!
     
  9. Dirk

    Dirk Dwarf Catfish

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    Hi Gareth,

    You have me thoroughly confused now. In guppies you can see the color of a strain based on the colors of the males. You cannot get an indication of the color the female carries, that is just a simple fact. So you must breed the "new" blue male back to his daughters, not daughters back to parents.

    You can continue inbreeding guppies for many generations, because they do not seem to carry many lethal genes. Inbreeding causes all the genes to have two identical copies (all genes are present in pairs in diploid organisms such as fish, one copy is contributed by the mother, one copy is contributed by the father), the technical term is called homozygous. So if you have an individual with one lethal copy and one non-lethal copy that individual would survive. If you were to inbreed this strain, then by chance sooner or later you would have a combination of two lethal genes which would mean that the individual would die. In humans we have many lethal genes and that is why inbreeding has so many negative consequences, in guppies on the other hand not so, inbreeding does not influence them so badly.

    And as soon as you outbreed, in other breed with a guppy of another strain, you can loose the blue, yes, and you would have to start the inbreeding process from scratch again.

    Last point: Once you have a strain fixed in other words that they breed true, in other words that all offspring are the same, you can perpetuate that strain by breeding brothers to their sisters in every generation.

    The joys of Mendelian genetics, the man made a huge contribution to our understanding of genetics and was never acknowledged for his contribution during his lifetime.

    Kind regards,

    Dirk
     
  10. Big G

    Big G Apisto Nutz!!!

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    Cheers Prof. Thats helped clear up my confusion a little I think?

    Regards!
    Big G!
     
  11. veegal

    veegal

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    A nice response there Prof - definitely not one to be read when you are dronk though :)
     
  12. OP
    Vis

    Vis Gerhard

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    Perfect Prof Thanks!

    @ Big G. No problem was thinking of that while I was reading:p

    Now that I know it is called Line breeding it should be easier to find info with google. Difficult to find something if you do not know what you are looking for but makes sense in your head.

    One more question: With guppies the females do not show colour meaning that males would have the dominate gene conserning colour?( this statement might be wrong?)

    Would it then not stand that you still have a big chance of getting blue offspring no matter to what female you cross them.

    With so little lethal genes I guess some inbreeding would not hurt to get to the goal.

    Thanks again.
     
  13. OP
    Vis

    Vis Gerhard

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    Found some diagrams which make it a little easier to grasp since your head work in pictures.

    Hope it is Ok to post the link.
    http://www.guppysa2z.com/clubs/sjgg/beginner.htm

    They use 1 male and 2 females to which you can crossbreed to prevent inbreeding a little.

    The attached chart shows the percentage of inherit blood/genes

    linebreedignchart.jpg
     
  14. Dirk

    Dirk Dwarf Catfish

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    Hi Big G,

    You are asking very pertinent questions here.

    In guppies males do not have the dominant genes concerning colour. It is the testosterone in the males that causes them to show colour and the production of colour is therefore sex dependent. The females have the genes for the colour but they cannot show them. You can do a lot of things by adding testosterone to the water of the fishes you keep, you can convert tiny female Malawi Cichlids to males, you can get young male and female discus to show turquoise colour when they are much younger. Normally this has major negative consequences for those on which the testosterone has been used on (or who use it, the big muscular guys at the gym, who have tiny testicles as a result of the testosterone treament, and who are sterile!), for example male discus that have been treated in this way are permanently sterilized. I believe, although I would not recommend it as it would have effects on reproductive ability I am sure, that you can treat young female guppies for a short period with testosterone for them to then look like males, but they do not become sex changed, and once you know what they look like, you stop the testosterone treatment and use them for breeding with the knowledge of knowing how they may look if coloured like males. This allows you to select those females that carry the colour that you wish to select for and it allows you to make progress with the selection of a line faster, BUT, you do not know how much damage the testosterone treatment has done. This damage is however very definitely not permanent in that it does not change genes, the only thing it can change is the reproductive ability of the female. (Pshew, what a mouthful).

    So, to get back to your second question, if in this way, you could identify the "best" female, in other words the one that looks like the blue male, you will make faster progress in "fixing" your new blue strain. This also means that you would do better with the female looking most similar to the blue male and it means that if you do not use the testosterone treatment and you choose the "wrong" female, in other words, the one that actually looks least like the blue male (because you do not really know what it looks like without testosterone treatment), you will make slower progress.

    If the genes that you start off with before inbreeding are "good" in other words do not carry lethal genes, then inbreeding does not really matter and you can inbreed regardless without negative consequences. However, most organisms do eventually show what is known as "inbreeding depression" as a result of many generations of inbreeding. For example, you cannot inbreed discus for more than six generations without having major effects, the fish become smaller, the brood sizes decrease, the growth rates become slower and the fish are less resistant to disease. In humans the example comes from the pharohs, who married their brothers and sisters because there were no other people in their opinion that were noblemen. As a result, the inbreeding stopped most kingdoms by the third generation due to degenerative problems, reproduction, teeth, and other deformities.

    This will give some more to google and wiki tonight!

    Kind regards,

    Dirk
     
  15. Big G

    Big G Apisto Nutz!!!

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    I think I'm starting to get this idea now!

    I assume this concept is very similar for different Fish Species, but obviously at times with a few variations and dificulties!?

    Cheers
    Big G!
     
  16. OP
    Vis

    Vis Gerhard

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    That is very interesting.

    Funny how nature always have a curve ball up her sleave.

    Another fynny thing is how the strain becomes weaker. If you get enough lethal genes together in one fish they will die or be deformed and be eliminated.
    I would think this would actually make the strain stronger as only the fish with strong and less lethal genes survive.

    But I guess it comes to a point where every single fish has to many bad genes.

    Maybe just a build in law of nature to prevent inbreeding.

    I have read somewhere that 96% or something like that of all pure black Betta female are sterile. Would be interesting to know if this was also because of inbreeding or some other genetic anomaly
     

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