Question on Recessive Genes

Discussion in 'General breed discussions & FAQ' started by jimnjay, Nov 21, 2009.

  1. jimnjay

    jimnjay Chillin' With My Peeps

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    This sound so dumb to me but I really don't know enough about how recessive genes work past the first generation. Will a bird that is Splash split for Lavender be able to pass the lavender gene to offspring? In this case the roo would be bred to black and blue or buff hens. I assume it may pass to the offspring but fewer of the offspring will have the lavender gene than if the Rooster displayed Lavender. I have a buff pen and I am getting white chicks hatching from them. I understand that both parents must have the recessive white gene but I am not sure weather the buff birds that hatch from these buff parents will pass the recessive white to any of their offspring. I suspect so but I just want clarification on how far out the recessive gene will pass down if the buff chicks are not bred back to a bird with the recessive white.

    I mention the buff because it helps me to understand how to breed the Splash boy Split for Lavender. I just acquired a Lavender pair and I am hoping to play with Porcelain like so many others but I am not sure if the Splash boy will be of any use at all.
     
  2. Year of the Rooster

    Year of the Rooster Sebright Savvy

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    I will help you as best as I can from the basic genetics knowledge from high school

    Let's say that B = buff and w = white. Make a punnet square for this (best I could do):

    B w
    B BB Bw
    w Bw ww

    Since the parents are producing white offspring that means each has a copy of the recessive white gene. This would make them Bw(in this example). Now, 25% of the offspring are recessive white. While 25% of the offspring are pure Buff and the other 50% are Buff, but carry recessive white. And there will be no way of knowing which Buff's are carrying the White unless you breed them (like you did with their parents.) So I would say that the white could be passed down for a while unless you cull very carefully. I hope this helped a little. [​IMG]
     
  3. blackdotte

    blackdotte Chillin' With My Peeps

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    A bird carrying a recessive gene will pass it to 50% of its offspring. The 50% that get it will pass it on to 50% of their offspring, ad infinitum. It will only show if the carrier birds are mated to a similar carrier.
    David
     
  4. Year of the Rooster

    Year of the Rooster Sebright Savvy

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    Quote:That's the short version of putting it! [​IMG]
     
  5. Sonoran Silkies

    Sonoran Silkies Flock Mistress

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    Quote:Of course this implies that buff & white are the result of one gene, which is not the case; buff is the result of a number of specific genes combined and recessive white hte result of one gene that is not included in the buff genotype. Also, B is the appreviation for barring, and w is the abbreviation for white skin [​IMG] c is the abbreviation for recessive white (C+ being "colour" and c being "not-colour")

    David explains how recessives are passed on very well.

    Let's say that you know which specific buff birds are the parents of the white chicks. You know that each of them carry one copy of recessive white. 25% of their babies will receive two copies of recessive white, 25% will receive no copies of recessive white. and the remaining 50% will receive one copy. With some recessive genes there is leakage, and you may be able to tell in the down or occasionally even adult feathering that a bird likely carries a specific recessive. White does not, and to the best of my knowledge, neither does lavender. Unless there is leakage, there is no way to ascertain which of the offspring carry one copy of a recessive and which carry none. You could, when grown, pair them with a bird pure for the recessive to see if any offspring hatch with that phenotype, in which case you will know that the bird does carry it.
     
  6. Year of the Rooster

    Year of the Rooster Sebright Savvy

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    Quote:Of course this implies that buff & white are the result of one gene, which is not the case; buff is the result of a number of specific genes combined and recessive white hte result of one gene that is not included in the buff genotype. Also, B is the appreviation for barring, and w is the abbreviation for white skin [​IMG] c is the abbreviation for recessive white (C+ being "colour" and c being "not-colour")

    David explains how recessives are passed on very well.

    Let's say that you know which specific buff birds are the parents of the white chicks. You know that each of them carry one copy of recessive white. 25% of their babies will receive two copies of recessive white, 25% will receive no copies of recessive white. and the remaining 50% will receive one copy. With some recessive genes there is leakage, and you may be able to tell in the down or occasionally even adult feathering that a bird likely carries a specific recessive. White does not, and to the best of my knowledge, neither does lavender. Unless there is leakage, there is no way to ascertain which of the offspring carry one copy of a recessive and which carry none. You could, when grown, pair them with a bird pure for the recessive to see if any offspring hatch with that phenotype, in which case you will know that the bird does carry it.

    Thank you Sonoran. I was only using B and w hypothetically. I knew there were other letters for those genes, but I hadn't a clue what they were. I guess that high school biology for ya [​IMG] [​IMG]
     
  7. Sonoran Silkies

    Sonoran Silkies Flock Mistress

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    I'm not sure I remember anything from HS biology---except that the teacher could read a thick paperback, and when he was done it never looked like it had been opened [​IMG] I think we had about a page and a half on Mendel and his pea experiments. And that was all the genetics we had.
     
  8. jimnjay

    jimnjay Chillin' With My Peeps

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    Thanks for all that information. It really helps. I plan to replace my rooster, I just acquired a new boy and hopefully he will not have the gene. I have three girls that are very light blond. Is there any relationship to the very blond birds being crossed with white to eliminate the dark feathers? I thought one used lavender to dilute but if there were no lavender Silkies around do people use white? My birds are virtually clear so I am thinking that there must have been some effort to dilute the dark feathers and the results ended up very blond.

    I love the blond color and that does not concern me but the white does.
     
  9. Sonoran Silkies

    Sonoran Silkies Flock Mistress

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    White does not dilute--it inhibits entirely. Blue, lavender, dilute, inhibitor of gold, champagne blonde, etc. dilute; reducing, but not eliminating the pigment.

    Dominant white eliminates black pigment when one copy is present and also red when a 2nd copy is present. However it replaces the pigment with white.
     
  10. tadkerson

    tadkerson Chillin' With My Peeps

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    Quote:That is sad. I taught all kinds of genetics; recessive, dominant, incomplete dominance, sex-linked, monohybrid, dihybrid, F1 generation, codominance, genotype, phenotype, phenotypic ratios and phenotype probabilities. My students learned to use Punnet squares and probability webs. I brought in my chickens and showed them examples of the different phenotypes associated with the genotypes. My students then worked with the genotypes and phenotypes in problems. I would give my students the F1 or F2 phenotypes and make them determine the phenotypes and genotypes of the parents. This was a general biology course; students learned much more in our AP Biology.

    I had a student CLEP out of general biology at the college level after taking the biology I taught them in the 10th grade.


    Sonoran Silkies I sent you an email your PM box is full.

    Tim
     
    Last edited: Nov 22, 2009

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