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  1. #101
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    Re: A Lesson in Basic Genetics

    Quote Originally Posted by snakesRkewl View Post
    There are no codominant traits in ball pythons.

    Pastel + mojave makes pastave where the two colors blend together.
    If they were codominant there would be parts of the snake looking like a pastel and parts looking like a mojave.
    The pastel and mojave genes are not members of the same gene complex. A pastave has two gene pairs of interest--a pastel gene paired with the corresponding normal gene and a mojave gene paired with its corresponding normal gene. Only genes of the same gene complex can be codominant/incomplete dominant. So pastave does not count.

    Codominance = Parts of the snake having one appearance and parts of the snake having a different appearance. This definition is inaccurate.

    The Burmese cat (cbcb) and the Siamese cat (cscs) have different colors because the cb and cs genes produce different amounts of melanin. Pictures of Burmese, Siamese and Tonkinese cats can be found in Wikipedia. The Tonkinese cat (cbcs) is intermediate in color because each color cell has a cb and a cs gene and each gene does its own thing. The two genes are codominant instead of incomplete dominant to each other because each gene produces a functional gene product.

    The only snake genes that I would call incomplete dominants in the strict sense are the amelanistic and hypo genes in the corn snake. Until other genes are characterized, we don't know for sure which are codominants and which are incomplete dominants. And arguing about which term to use is pointless.

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  3. #102
    BPnet Veteran Ronniex2's Avatar
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    new to morphs

    Thanks 1100000 i was just thinking of how i am going to deal with looking for a new mate for my snake and now this read has made the search much more clear.

    Thanks again!

  4. #103
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    What does each Morph mean?

    I am very new to the snake world and trying to learn. I see all the posts naming different types of morphs , but I am having a little trouble differentiating them... How do you visually depict what morph the snake is? The very common ones I see are

    Spider
    pinstripe
    pastel
    Axanthic
    lesser
    GHI
    Fire
    cinnimon
    mojave
    Ghost

    if I’m looking at a snake at the store, how can I accurately depict what it is?
    thank you for your time on any/all responses

  5. #104
    BPnet Veteran Godzilla78's Avatar
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    A Lesson in Basic Genetics

    Spend hours and hours on www.morphmarket.com and you will be an expert in no time.
    Just lock up your credit cards and your paypal account while you are browsing. Lol


    Sent from my iPhone using Tapatalk
    Last edited by Godzilla78; 03-05-2018 at 12:24 AM.

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  7. #105
    BPnet Senior Member artgecko's Avatar
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    Re: What does each Morph mean?

    Quote Originally Posted by Dbluedevil02 View Post
    I am very new to the snake world and trying to learn. I see all the posts naming different types of morphs , but I am having a little trouble differentiating them... How do you visually depict what morph the snake is? The very common ones I see are

    Spider
    pinstripe
    pastel
    Axanthic
    lesser
    GHI
    Fire
    cinnimon
    mojave
    Ghost

    if I’m looking at a snake at the store, how can I accurately depict what it is?
    thank you for your time on any/all responses

    The ones you listed, with the exception of fire, are all pretty easy to visually differentiate. Some of the other morphs, like yellow belly for example, are harder to determine.

    I would research on morph market and WOBP and note the visual characteristics of the moprhs you are interested in. Odds are, if you see a BP at a store and it looks "normal", then it is a normal and not a morph. I would also advise buying from a good breeder vs. a store, as they can give you background info on the snake, tell you about feeding habits, parents, etc. But again, check reputations before you buy from anyone either here or on the fauna classifieds BOI.
    Currently keeping:
    1.0 BCA 1.0 BCI
    1.0 CA BCI 1.1 BCLs
    0.1 BRB 1.2 KSBs
    1.0 Carpet 0.5 BPs
    0.2 cresteds 1.2 gargs
    1.0 Leachie 0.0.1 BTS

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  9. #106
    BPnet Veteran BeansTheDerp's Avatar
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    Re: A Lesson in Basic Genetics

    super duper helpful! bit confusing but just what I was looking for!
    Be kind, and inspire others to be kind.

  10. #107
    BPnet Lifer snakesRkewl's Avatar
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    Re: A Lesson in Basic Genetics

    Quote Originally Posted by paulh View Post
    The pastel and mojave genes are not members of the same gene complex. A pastave has two gene pairs of interest--a pastel gene paired with the corresponding normal gene and a mojave gene paired with its corresponding normal gene. Only genes of the same gene complex can be codominant/incomplete dominant. So pastave does not count.
    Every single visual mutation that we work with is incomplete dominant, there are zero codominant traits proven in ball pythons. Codominant will not blend like incomplete dominance when added to another mutation. Pastel is incomplete dominant, as is mojave. Each on their own, incomplete dominant traits. Codominant would be if we added pastel to mojave and sections of the snake would look like a mojave and section would look like a pastel. Instead they blend together. That is how incomplete dominant traits work.
    Jerry Robertson

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  12. #108
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    Re: A Lesson in Basic Genetics

    Quote Originally Posted by snakesRkewl View Post
    Every single visual mutation that we work with is incomplete dominant, there are zero codominant traits proven in ball pythons. Codominant will not blend like incomplete dominance when added to another mutation. Pastel is incomplete dominant, as is mojave. Each on their own, incomplete dominant traits. Codominant would be if we added pastel to mojave and sections of the snake would look like a mojave and section would look like a pastel. Instead they blend together. That is how incomplete dominant traits work.
    As I wrote in post 101 in this thread, pastel and mojave are independent genes. Only different versions of the same gene can be dominant/recessive/codominant/incomplete dominant to each other. Normal/pastel/super pastel is relevant, and normal/mojave/super mojave is relevant. The relationship between pastel and mojave is not relevant.

    Strangely enough, if you look at Burmese, Siamese and Tonkinese cats, the Tonkinese (the heterozygous cat) is intermediate in color between the other two. Just like pastel ball pythons are intermediate in color between the normal and super pastel ball pythons. And the Siamese and Burmese genes have been identified as codominant to each other for decades.

    Definitions tend to change over time. The USA National Institute of Health's genetics glossary lists only codominance. See https://www.genome.gov/genetics-glossary/Codominance. There is no listing for incomplete dominance. Red/pink/white flowers have been considered an instance of incomplete dominance. The human A, AB and B blood types have been considered instances of codominance. Now, both are listed as forms of codominance in the NIH glossary. That turns "codominance" and "incomplete dominance" into synonyms and makes this discussion moot.

  13. #109
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    Re: A Lesson in Basic Genetics

    Can you tell which parts of this graphic are right, and which are wrong?



    Right: The pictures of the snakes. And a het albino x het albino mating does produce 25% normal offspring, 50% normal-looking het albino offspring, and 25% albino offspring.

    Wrong: The DNA graphics, gene pairs, DNA transmission from parents to offspring. And the allele symbols do not follow accepted rules.

    Nearly everything wrong can be traced back to one incorrect belief: that a DNA molecule is made up of two alleles side by side. This would require the parent DNA molecules to unzip down the length of the molecule. Then the mother’s half molecule fuses with the father’s half molecule in the fertilized egg. Egg fertilization does not work that way. Two alleles are in two separate DNA molecules, and those two DNA molecules are in separate chromosomes.

    Also, the gene symbols do not follow Gregor Mendel’s upper and lower case convention. Mendel, the father of genetics, defined dominant and recessive alleles in his original paper. He used the “A” and “a” characters to symbolize two alleles, as unknowns can be symbolized in algebra. Upper case “A” was assigned to the dominant allele, and lower case “a” was assigned to the recessive allele. Geneticists have followed this upper and lower case convention ever since.


    HOW DNA AND GENES WORK

    Picture two shoestrings. Each shoestring is coiled in a spiral. Hold them up side-by-side. A spiral is also known as a helix.



    Now picture the shoestrings with a series of colored balls strung along each string.



    Two corresponding colored balls form a base pair. The base pairs hold the two shoestrings together in a double helix. This is the structure of a DNA molecule. The sequence of base pairs is the genetic code.



    A gene is a segment of a DNA molecule that functions as a single unit. Genes are strung along a DNA molecule. DNA molecules and their genes are found in chromosomes. Many genes have over a thousand base pairs. And many chromosomes have over a thousand genes. Most vertebrates have several billion (yes, billion) base pairs in the DNA.

    During most of a cell’s life, a chromosome is an invisible thread. When a cell starts to divide, each DNA molecule replicates into two DNA molecules. And for a very short time each chromosome becomes X-shaped. This is the only time in a cell’s life that the chromosomes are visible.



    A pair of chromosomes can also be represented as two rods with colored segments. Each colored segment represents a single gene. Each pair of segments represents a pair of genes with a specific residence in the chromosomes, a locus. Locus is pronounced “low cuss”. The plural of locus is loci, which is pronounced “low sigh”. Alleles form gene pairs. Two alleles are in two chromosomes but have only one locus.



    Each pair of genes has a different job in determining the look of an animal. It takes many different pairs of normal genes, each controlling a specific job in an assembly line, to make the normal pattern and colors of a snake. If just one normal gene is changed to a mutant gene, the assembly line gets blocked or diverted. And what rolls off the end of the line is not normal.


    Genes come in pairs, like socks. In a homozygous gene pair, the two genes are the same. Two normal genes, two albino genes, two pinstripe genes, or two mojave genes. In a heterozygous (aka het) gene pair, the two genes are different. A normal gene and an albino mutant gene, a normal gene and a pinstipe mutant gene, or a lesser mutant gene and a mojave mutant gene. A heterozygote is an individual with a heterozygous gene pair, and a homozygote is an individual with a homozygous gene pair. As ball pythons have something like 25,000 gene pairs, one snake can have both homozygous gene pairs and heterozygous gene pairs.




    For many years, herpers assumed that all heterozygous snakes looked normal. But appearance has never been part of the definition of “heterozygous”. The appearance of the heterozygote determines whether one allele is dominant, codominant or recessive to the other allele.

    For more information about DNA and genes, see the USA National Institute of Health’s Handbook of Genetics, https://medlineplus.gov/genetics/und...g/basics/cell/.


    When two animals mate and create young, the father contributes a sperm and the mother contributes an egg. Ball pythons, boa constrictors, corn snakes and many other snakes have 18 pairs of chromosomes. The total number of chromosomes is 36. Sperm and eggs are produced in a two stage process named meiosis. Each sperm or egg gets one chromosome from each pair of parental chromosomes, for 18 chromosomes. A ball python fertilized egg has both the 18 sperm chromosomes and the 18 egg chromosomes, making 18 new pairs of chromosomes in the offspring.




    So what happens when I breed XXX to xxx?

    Definitions:
    Wild type (aka normal, standard) = 1. The most common allele at a given locus in the wild population of a species. 2. The most common look (phenotype) in the wild population of a species.

    Mutant (aka abnormal) = 1. Not the most common allele at a given locus in the wild population of a species. 2. Not the most common look (phenotype) in the wild population of a species.


    Mendel’s upper and lower case convention is easy to follow when working with the ball python’s albino and normal alleles. The upper case “A” symbol is assigned to the dominant allele, which happens to be the normal allele. And the lower case “a” symbol is assigned to the recessive allele, which happens to be the albino mutant allele.

    When mating two het albino (Aa) ball pythons, each egg or sperm gets one member of each gene pair. Half of the mother’s egg cells have a chromosome with a normal allele (A), and half of the eggs have a chromosome with a mutant allele (a). Half of the father’s sperm cells have a chromosome with a normal allele (A), and half of the sperm have a chromosome with a mutant allele (a).

    An A egg can be fertilized by either an A sperm or an a sperm. And an a egg can be fertilized by either an A sperm or an a sperm. This produces four possible gene pairs, AA, Aa, aA, and aa. As the order of the genes in the gene pairs does not matter, the Aa and aA gene pairs are combined into the Aa category.



    The outlines of the eggs, sperm and fertilized egg can be ignored. That leaves only the chromosomes with the A and a genes. And the orientation can be changed from horizontal to vertical. This gives a more accurate version of the first graphic in this post.



    For simplicity, the graphic can be converted into a Punnett square:



    The Punnett square can be put on a single line as “Aa mated to Aa produces 1/4 AA, 2/4 Aa, 1/4 aa.” That can be further abbreviated to “Aa x Aa → 1/4 AA, 2/4 Aa, 1/4 aa.”


    Suggested practice problems. What are the offspring’s genes in these problems? What do both parents and offspring look like?

    A = normal gene (dominant), a = albino mutant gene (recessive).
    AA x AA → ???
    AA x Aa → ???
    AA x aa → ???
    Aa x aa → ???
    aa x aa → ???

    Y = yellowbelly mutant gene (codominant), y = normal gene (codominant).
    YY x yy → ???
    Yy x yy → ???
    Yy x Yy → ???

    P = pinstripe mutant gene (dominant), p = normal gene (recessive).
    pp x PP → ???
    pp x Pp → ???
    Pp x Pp → ???

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  15. #110
    BPnet Veteran nikkubus's Avatar
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    While the Dom/rec Capital/lowercase is the proper convention, logically it doesn't really make sense when dominance isn't binary, but hierarchy, and some allelic genes have equal dominance. I feel like it could really use a revamp of convention. Doesn't matter too terribly much in BPs, since there aren't any I know of morph wise, but mice for example have many cases of that.

    The two examples you give with incomplete dominants at the bottom should all have caps per the convention with different exponents if I remember correctly. I don't know what the exact letters would be but something like Y= wild type on YB allele, Y^yb = Yellow Belly, P = wild type on Pin allele, P^i = Pinstripe or something like that. Here is an example for human blood type that demonstrates what I'm talkng about, where A and B have equal dominance but O is recessive to both:
    7.22 BP 1.4 corn 1.1 SD retic 0.1 hognose

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