Walter Smith
CRAZY BOUT' CORNS !!
Mine is Lava het Cinder
It may be a while before we here from Carol. She stays VERY busy and does not hit the forums daily.
Walter
:crazy02:BOUT' CORNS !!
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PILE-O LAVAS & LAVA CINDERS !!
- Thread starter Walter Smith
- Start date
Mine is Lava het Cinder
It may be a while before we here from Carol. She stays VERY busy and does not hit the forums daily.
Walter
:crazy02:BOUT' CORNS !!
DuxorW
Derailer of Threads
After looking at her post in her forum, it looks like her female is het lava cinder, which is good because I expect a skewed phenotypic ration if the female is het lava cinder or lava het cinder. For reasons I will explain, I expect that it is also possible to get all female lava cinders and no males, although you should get the same repeatable result for each dame. Ie, one dame might throw all male lava cinders when mated to a male lava cinder, whereas another female might consistently throw all female lava cinders. My theory predicts that you will be able to get both male and female lava cinders if the female is homozygous cinder het lava.
Walter Smith
CRAZY BOUT' CORNS !!
Yes.......2012 & 2013 ~ SIRE Buttermint (Butter Cinder) X DAME Amel het Caramel Cinder. ALL homo Cinders in the clutches were males, even the non Caramel one (Peppermints)
After I got the same results in 2013 as in 2012, then started me thinking of the PROVEN testings in the Banana/CG Ball Pythons.
This year between myself seeing them again with a totally different pair AND the fact that Carol is seeing it,
that's where it's got me thinking this could actually be the case ??? :shrugs:
Walter
:crazy02:BOUT' CORNS !!
cornmorphs
New member
Heres on for you Carola dn WalTer.. I have probably hatched well over 100 cinder based snakes now.... I have had about 3 females ever... So literally we are talking about 1-2% maybe.
I'm eagerly awaiting this explanation! I know the BP people are stumped on exactly how this works, specifically the part about how it seems to switch back & forth between being sex linked to females then sex linked to males. They are at this point sure it is sex linked, but don't understand why it doesn't follow the rules of sex linked traits in humans.
Walter Smith
CRAZY BOUT' CORNS !!
Interesting, thanks for the info.
If you could post what the parents of those offspring were Phenotypically and Genotypically, that may help out as well.
SIRE: Homo or Het X DAME: Homo or Het
BTW, as I sit here and think about it, I don't think I've ever produce a female that was Homo Cinder............that I can recall.
Of course I've only been producing Cinder Morphs for a few years now.
Walter
:crazy02:BOUT' CORNS !!
Walter Smith
CRAZY BOUT' CORNS !!
DuxorW
Derailer of Threads
Ok, here goes. This might require that you do a little googling a few subjects to avoid this being overly long, such as: meiosis, sex linkage, and crossing over.
In humans, males and females are the heterogametic and homogametic sexes, respectively, meaning that males have two different sex chromosomes (X and Y) and females have two of the same type of sex chromosome (XX). In birds and some non-avian reptiles, it is the FEMALE that is the heterogametic sex. In this system, the sex chromosomes are referred to as Z and W, and males are ZZ and females are ZW. Colubrid snakes use this ZW system.
In reptiles that use the ZW system, it is likely that the Z and W chromosomes are more similar in size than the X and Y in humans. That makes it possible that they share many of the same genes. If you refer to my color blindness explanation in an earlier post, we saw that in humans, genes on the X chromosome do not have a partner on the Y chomosome. That is why males who have a recessive mutation on the X chromosome will show the phenotype anyway. Females have two copies of the X chromosome but can still exhibit a sex-linked phenotype if the father was affected and the mother was a carrier (the odds in that case would be 50:50 for the daughters). If the cinder gene is sex-linked, why are people having trouble getting lava cinders if the father shows the trait and the mother is a carrier for both mutations? Shouldn't have the lava cinder offspring be female?
In the ZW system, a gene on the Z chromosome can also have an allele on the W chromosome. We do not know if it is the presence of two Z chromosomes that causes maleness in snakes or if it is the presence of a single W chromosome that causes femaleness, but for this discussion I will assume for simplicity that a region of the W chromosome determines femaleness in snakes. I am proposing that the cinder locus is on both the Z and W chromosomes. A male can be homozygous cinder by having the cinder mutation on both of his Z chromosomes, whereas a female would be homozygous cinder by having the cinder mutation on her Z chromosome and her W chromosome.
Here comes the fun part. If a female has the cinder mutation on her Z chromosome and the wild type allele on her W chromosome and mates with a HOMOZYGOUS cinder male, all of her male offspring (who are ZZ) should be cinder, and all of her female offspring (who are ZW) will not be cinder, because they had to inherit their W chromosome from their mother, who had the wild type allele on her W chromosome.
If this is true, how is it that we get females that are homozygous cinder?
In humans, during meiosis, each chromosome pairs with its "homologue." (For example, chromosome 9 will line up with the other chromosome 9). The two homologous chromosomes were inherited from the father and mother. The paired homologous chromosomes will break and exchange pieces in a process called crossing over, which results in a new combination of maternal and paternal alleles on the same chromosome. In humans, the X and Y chromosome undergo this process, but because the Y chromosome is so tiny and has few regions of similarity to the X chromsome, it has no real genetic consequence.
However, in an animal with two sex chromosomes that are far more similar, this could affect the pattern of inheritance of genes on the Z and W chromosomes. A chromosomal crossover occurs randomly during meiosis, but if we take any two genes, the closer they are, the less likely a crossover will occur between them. Also, the less similar two chromosomes are from one another, the less likely a crossover will occur between them. Lastly, crossovers are less likely to occur near regions of the chromosome called centromeres. Regardless, I suspect that the cinder locus is on the Z and W chromosomes and that for whatever reason a crossover between Z and W chromosomes at the cinder locus is rare but possible. Thus, in a female with the cinder mutation on the Z chromosome, there is a small possibility that the region of the Z chromosome containing the cinder locus crosses over with the region of the W chromosome containing the cinder locus. If the female is het cinder and the mutant allele is on her Z chromosome, a crossover during meiosis would now put the cinder mutation on the W chromosome of the resulting gametes, and the wild type allele on the Z chromosome. Remember, meiosis involves two cell divisions. The second division of meiosis halves the chromosome number, so an egg cell only receives the Z OR W chromosome. Egg cells with the Z chromosome will give rise to males after fertilization, and egg cells with the W chromosome will give rise to females.
Thus, when mated to a cinder male, the cinder offspring of a het cinder female (with the cinder mutation on her Z chromosome) should be male, but a crossover event during meiosis gives a small probability that female cinders will be produced, as the mutant allele can be swapped from the Z chromosome to the W chromosome in a small number of gametes. In a cinder male x het cinder female (with the cinder mutation on her W chromosome) cross, the cinder offspring should be female unless there was a meiotic crossover.
A female cinder or cinder combo will have the cinder mutation on both her Z and W chromosomes, and should produce a roughly equal number of cinder males and females when paired with a cinder or het cinder male (this is a test of my hypothesis!).
Nanci asked me to mention what would happen if both the sire and the dame are het lava cinder. If the lava gene is not on the same chromosome as the cinder gene, the inheritance of one mutation does not affect the other. You should get an equal mix of male and female lavas, but due to the cinder locus being on the Z and W chromosomes, you would expect most of the homozygous cinder offspring, whether lava or not, to be skewed towards all male or all female.
I am not a breeder of corn snakes so there are some observations that could easily disprove this, but it sounds like people are having skewed ratios of homozygous cinders when the mother is HET cinder, which supports this scenario. This should not occur when the female is homozygous cinder.
Thus, if you want to increase the amount of female cinder combos you produce, you would want to use a homozygous cinder female. For example, mate a buttermint male with a peppermint female. The peppermint het caramel females produced by this pairing should produce an equal amount of male and female buttermints when crossed to a male buttermint (or peppermint het caramel, or cinder het caramel het amel...you get the idea!).
In humans, males and females are the heterogametic and homogametic sexes, respectively, meaning that males have two different sex chromosomes (X and Y) and females have two of the same type of sex chromosome (XX). In birds and some non-avian reptiles, it is the FEMALE that is the heterogametic sex. In this system, the sex chromosomes are referred to as Z and W, and males are ZZ and females are ZW. Colubrid snakes use this ZW system.
In reptiles that use the ZW system, it is likely that the Z and W chromosomes are more similar in size than the X and Y in humans. That makes it possible that they share many of the same genes. If you refer to my color blindness explanation in an earlier post, we saw that in humans, genes on the X chromosome do not have a partner on the Y chomosome. That is why males who have a recessive mutation on the X chromosome will show the phenotype anyway. Females have two copies of the X chromosome but can still exhibit a sex-linked phenotype if the father was affected and the mother was a carrier (the odds in that case would be 50:50 for the daughters). If the cinder gene is sex-linked, why are people having trouble getting lava cinders if the father shows the trait and the mother is a carrier for both mutations? Shouldn't have the lava cinder offspring be female?
In the ZW system, a gene on the Z chromosome can also have an allele on the W chromosome. We do not know if it is the presence of two Z chromosomes that causes maleness in snakes or if it is the presence of a single W chromosome that causes femaleness, but for this discussion I will assume for simplicity that a region of the W chromosome determines femaleness in snakes. I am proposing that the cinder locus is on both the Z and W chromosomes. A male can be homozygous cinder by having the cinder mutation on both of his Z chromosomes, whereas a female would be homozygous cinder by having the cinder mutation on her Z chromosome and her W chromosome.
Here comes the fun part. If a female has the cinder mutation on her Z chromosome and the wild type allele on her W chromosome and mates with a HOMOZYGOUS cinder male, all of her male offspring (who are ZZ) should be cinder, and all of her female offspring (who are ZW) will not be cinder, because they had to inherit their W chromosome from their mother, who had the wild type allele on her W chromosome.
If this is true, how is it that we get females that are homozygous cinder?
In humans, during meiosis, each chromosome pairs with its "homologue." (For example, chromosome 9 will line up with the other chromosome 9). The two homologous chromosomes were inherited from the father and mother. The paired homologous chromosomes will break and exchange pieces in a process called crossing over, which results in a new combination of maternal and paternal alleles on the same chromosome. In humans, the X and Y chromosome undergo this process, but because the Y chromosome is so tiny and has few regions of similarity to the X chromsome, it has no real genetic consequence.
However, in an animal with two sex chromosomes that are far more similar, this could affect the pattern of inheritance of genes on the Z and W chromosomes. A chromosomal crossover occurs randomly during meiosis, but if we take any two genes, the closer they are, the less likely a crossover will occur between them. Also, the less similar two chromosomes are from one another, the less likely a crossover will occur between them. Lastly, crossovers are less likely to occur near regions of the chromosome called centromeres. Regardless, I suspect that the cinder locus is on the Z and W chromosomes and that for whatever reason a crossover between Z and W chromosomes at the cinder locus is rare but possible. Thus, in a female with the cinder mutation on the Z chromosome, there is a small possibility that the region of the Z chromosome containing the cinder locus crosses over with the region of the W chromosome containing the cinder locus. If the female is het cinder and the mutant allele is on her Z chromosome, a crossover during meiosis would now put the cinder mutation on the W chromosome of the resulting gametes, and the wild type allele on the Z chromosome. Remember, meiosis involves two cell divisions. The second division of meiosis halves the chromosome number, so an egg cell only receives the Z OR W chromosome. Egg cells with the Z chromosome will give rise to males after fertilization, and egg cells with the W chromosome will give rise to females.
Thus, when mated to a cinder male, the cinder offspring of a het cinder female (with the cinder mutation on her Z chromosome) should be male, but a crossover event during meiosis gives a small probability that female cinders will be produced, as the mutant allele can be swapped from the Z chromosome to the W chromosome in a small number of gametes. In a cinder male x het cinder female (with the cinder mutation on her W chromosome) cross, the cinder offspring should be female unless there was a meiotic crossover.
A female cinder or cinder combo will have the cinder mutation on both her Z and W chromosomes, and should produce a roughly equal number of cinder males and females when paired with a cinder or het cinder male (this is a test of my hypothesis!).
Nanci asked me to mention what would happen if both the sire and the dame are het lava cinder. If the lava gene is not on the same chromosome as the cinder gene, the inheritance of one mutation does not affect the other. You should get an equal mix of male and female lavas, but due to the cinder locus being on the Z and W chromosomes, you would expect most of the homozygous cinder offspring, whether lava or not, to be skewed towards all male or all female.
I am not a breeder of corn snakes so there are some observations that could easily disprove this, but it sounds like people are having skewed ratios of homozygous cinders when the mother is HET cinder, which supports this scenario. This should not occur when the female is homozygous cinder.
Thus, if you want to increase the amount of female cinder combos you produce, you would want to use a homozygous cinder female. For example, mate a buttermint male with a peppermint female. The peppermint het caramel females produced by this pairing should produce an equal amount of male and female buttermints when crossed to a male buttermint (or peppermint het caramel, or cinder het caramel het amel...you get the idea!).
Wow. I think that makes sense. I knew that sex chromosomes on reptiles were different from humans in that it is the female that determines the gender of the offspring. I had no idea about the other part that allows for very little crossover in humans but more in reptiles. Cool.
If I I did in fact followed that explanation, this also means that "phet" cinders from a het cinder female aren't very "possible" at all, as long as the parentage or other offspring of the het cinder allows you to know which chromosome she carries the cinder mutation on. When mated to a non-cinder male, a het cinder female who carries the cinder gene on her Z chromosome will have male offspring that are het cinder, and female offspring that aren't het cinder. And the reverse for a het cinder female who carries the cinder gene on her W chromosome. With the rare exception of one of those crossovers you speak of.
If I I did in fact followed that explanation, this also means that "phet" cinders from a het cinder female aren't very "possible" at all, as long as the parentage or other offspring of the het cinder allows you to know which chromosome she carries the cinder mutation on. When mated to a non-cinder male, a het cinder female who carries the cinder gene on her Z chromosome will have male offspring that are het cinder, and female offspring that aren't het cinder. And the reverse for a het cinder female who carries the cinder gene on her W chromosome. With the rare exception of one of those crossovers you speak of.
Walter Smith
CRAZY BOUT' CORNS !!
Ok, it seems test breeding need to be done to see what's happening and to determine if your hypothisis is correct and I'm guessing these should be the test breedings.
Also what should be the outcome from each breeding as far as sex ratio?
SIRE: Cinder X DAME: het Cinder
SIRE: het Cinder X DAME: Cinder
SIRE: Cinder X DAME: Cinder
SIRE: het Cinder X DAME: het Cinder
One other question, IF breeding SIRE: Cinder X DAME: het Cinder DOES produce ALL male offspring, would the NON Cinder offspring be ALL female or would there be a female to male ratio between just them ??
Just a FYI, the 3 Lava het Cinders produced in my breeding are ALL females.
Walter
:crazy02:BOUT' CORNS !!
DuxorW
Derailer of Threads
The cinder offspring should be predominantly male or predominantly female.
The cinder offspring should have a roughly equal sex ratio.
Cinder X Cinder will give all cinders.
The cinder offspring of het cinder x het cinder should have a roughly equal sex ratio.
The 3 lava het cinders produced by your breeding would be consistent with my hypothesis.
I assume you mean if all the cinder offspring are male? If all the cinder offspring are male, it means the female had the cinder mutation on her Z chromosome and the wild type allele on her W chromosome. Thus, all the males should be cinder and all the females should be het cinder on their Z chromosome. So the NON cinder offspring will all be female unless there is a crossover.