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The Cultivars (morphs)/Genetics Issues Discussions about genetics issues and/or the various cultivars for cornsnakes commercially available.

Virgin Corn Laid Fertile Eggs!
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Old 12-03-2004, 02:18 AM   #11
Tearak
Thank you all for your replies!

I will hopefully be able to get some photos this weekend. Out of the 8 babies, there were 5 males and 3 females. One of the males was an anerythristic, but turned very light as he got older (he almost looks like a Anerythristic Okeetee).

I am absolutely positive there were no other snakes with this ghost female. She was in a plastic tub from the day she hatched and never ever put with a male - not even for a short while. This all happened the breeding season 2 years ago.

I paired the same female ghost up with one of the male ghosts last breeding season (September 2003) and she laid 14 eggs. All the babies were beautiful, light ghosts. So I have absolutely no idea how all the babies came out looking so different when she fertilised herself!

The wierd thing is now I have discovered another one of my young hypo females is gravid. She has DEFINATELY NEVER been with a male - that I know for sure! Although she is exceptionally large for her age (20 months), I only had plans to breed with her next season. She is het for motley, so it will be interesting to see what babies come out of her. She certainly looks like she's carrying good eggs, but who knows if they will be fertile?

Thanks again for all your comments. I'll put up a picture shortly.
 
Old 12-03-2004, 02:52 AM   #12
Jason B.
OK this has never been seen before in corns , now you have two asexual corns.Also a little bit rare to have a gravid corn in december alough if serp and Hurley say they have them , I believe that part at least.
 
Old 12-03-2004, 03:16 AM   #13
Tearak
Smile

Sorry about the confusion. I live in South Africa and it's summer time here at the moment and breeding time for our snakes. Ours come out of brumation in August and start mating in September (our spring time). Our eggs start hatching in January, and some people even have there's hatching in December.

Your hatching time is June/July - is this correct?

I will keep you posted about the Virgin Hypo's eggs - they might even be infertile afterall, but judging by the size and shape of her, she's carrying good eggs.

Thanks and kind regards,
Chantel (SOUTH AFRICA)
 
Old 12-03-2004, 07:53 AM   #14
Joejr14
Quote:
Originally Posted by E. g. guttata
Here is something I found on parthenogenesis. If I am reading this correctly, there is an outside chance that these corns would be male (haploid) and therefore look different from their mother. Not sure, but it's all I've got. Please post pics ASAP.
Serp's response confused me as I was just about to respond to this. In most everything else, a female only carries the female gene. Obviously in humans, female is XX, male is XY.

I guess in corns that's not the case. However, if parthenogensis did occur in humans, the only possible scenario would be all females---it would be impossible for the resulting offspring to have male genes.

This is all very interesting though.

Serp, how do we know that corns carry both genes? Do temps affect the offspring gender produced? I'm a bit confused here?
 
Old 12-03-2004, 08:18 AM   #15
princess
An idea...

Depending on the size of your corn collection, finances and the colour of the offspring, you could have the babies DNA charted and compared to possible fathers in your cornsnake collection. You could perhaps start with the most likely fathers colourwise and automaticly eliminate ones with a genetic background that would exclude them from the potential fathers list. It could be that someone put them together without telling you as a joke -or do you have kids in the house who might have wanted the snakes to get 'married' ?!!!!!? -Just an idea. Otherwise I have to agree with the scientific facts stated earlier. If she has in fact cloned herself there is no chance of her producing males and they would all come out the same morph as the mother so I have to say it would be more likely to be an accidental breeding.
 
Old 12-03-2004, 08:37 AM   #16
Tearak
Thanks for your suggestion Princess. Unfortunately that's not an option. I've been baffled about this for ages but I certainly didn't have any idea it would evoke so much response. My fiance takes care of all his venomous snakes and I take care of all the corns and all our other non-venomous snakes. This is why I know for certain that she was never paired up with any other snake, not even accidently. Anyway, at the time she wasn't healthy and was showing signs of having a bacterial infection and I most certainly wouldn't have let her near my other snakes in fear of the infection spreading to any other snakes. We are extremely careful with the snakes.
 
Old 12-03-2004, 01:09 PM   #17
Serpwidgets
In corns, the sex chromosomes are Z and W. The male is ZZ and the female is ZW.

This is a page with some useful accounts of cases that occured in snakes.
http://home.pcisys.net/~dlblanc/arti...enogenesis.php

I've also seen references to chemically induced incidents. I'm not sure what the case may be in your situation. Can you be a little more specific about the appearance of the offspring? Were they ghost-like, anery-like, hypo-like, normal-like, snow-like, etc? (Or I can just wait for pictures. )

Here's an article explaining the burmese python (good reading)
http://www2.rnw.nl/rnw/en/features/s...0224snake.html

As far as the burmese throwing all females and them being identical to the scale, I only found reference to the embryos. They were all females because they were diploid, whereas if they're haploid they'd be all males. Did someone incubate and hatch eggs from this female? The report I found was written before anyone had done so, but they said they intended to.

I'm pretty sure the twins I hatched in 2003 were monozygotic. They were a lot more similar than any two corns I've ever seen, but they still were not identical in pattern. I would not expect even identical twins to have perfectly matched patterns, there are too many other variables involved, IMO.
 
Old 12-03-2004, 02:41 PM   #18
Sisuitl
Just out of curiosity, is the young hypo female related to your ghost female at all? I know that this type of thing can run in families. I have a strain of chickens that will produce a self fertilizing hermaphroditic egg laying rooster every once in a while. When we have hatched chicks from them they usually look very different from the parent, but the parents are not homozygous for anything either. Here is a very interesting article on parthogenesis.

Personally I wonder if more corns aren't capable of this, but their keepers just don't both to incubate the eggs since they expect them to be infertile. Hmmm.....

Parthenogenesis in Livebearing Snakes...Explained
by Donald L. Blanchard
This article was originally published in The Cold Blooded News, the newsletter of the Colorado Herpetological Society, Vol 25, #11, November,1998.


--------------------------------------------------------------------------------
The following report is derived in part from a presentation given to the Tucson Herpetological Society by Gordon W. Schuett, Department of Life Sciences, Arizona State University West, Phoenix, Arizona, on September 16, 1997, as reported in The Sonoran Herpetologist, the Newsletter of the THS, Vol.11, No.9, September, 1998.


--------------------------------------------------------------------------------
Parthenogenesis, reproduction without fertilization by a male, has been reported in only a few different groups of reptiles, most notably New World lizards of the genus Cnemidophorus (family Teiidae), Old World lizards of the genus Lacerta (family Lacertidae), and the Brahminy blind snake (Ramphotyphlops braminus; family Typhlopidae). In all of these cases, the populations are composed entirely, or almost entirely, of genetically identical female individuals, or clones. Thus, it came as quite a surprise when Dr. David Chiszar of the University of Colorado, Boulder, found that a timber rattlesnake (Crotalus horridus) in his lab that had never been with a male since its birth had produced a litter of offspring: one live, two stillborn, and three infertile eggs. More surprising was the fact that the live and stillborn offspring were all males. Clearly, this parthenogenetic reproduction was different than that practiced by the known unisexual reptiles. (This event was reported to the CHS by Dr. Chiszar in January of 1996.)
In October of 1995, Dr. Chiszar reported this odd occurrence by telephone to Gordon W. Schuett, at Arizona State University. Schuett had been studying sperm storage in reptiles, and was faced with a puzzle of his own: a wandering garter snake (Thamnophis elegans vagrans) that had been producing litters, some with viable offspring, in the absence of males for about 10 years. Schuett utilized the now familiar method of DNA fingerprinting to test for any paternal contribution to the offspring. DNA fingerprinting separates the genetic material of an individual, so that it appears as a long series of bands, each corresponding to a particular genetic component in the individual's DNA. Parents are determined by matching shared bands; the more bands that match, the greater the probability that a parent has been found. A perfect match of band-sharing between two individuals (in number and location of bands) indicates a very close genetic relationship, such as found in identical twins or clonal species like the unisexual Cnemidophorus.

Schuett found that the mother garter snake had up to twice as many bands as the offspring, not an anticipated result, but that those bands possessed by the offspring matched almost perfectly with those of the mother, indicating that all the DNA in the offspring came from the mother, but that not all the mother's DNA was present in the offspring. Thus, this was a true parthenogenesis, with no male contribution (which would have provided genetic material to the offspring that was different from that provided by the mother). But the missing DNA from the mother, coupled with the fact that all the offspring were males, lead Schuett to the conclusion that the reproduction observed was a form known as automictic parthenogenesis (AP). AP had been previously described in domestic turkeys and chickens, and the offspring produced are all diploid males. (Diploid is the normal condition for sexual reproduction, indicating that all chromosomes occur in pairs.)

To understand automictic parthenogenesis, one must first understand meiosis, the process by which sex cells (eggs and sperm) are produced. In normal cell division, or mitosis, every chromosome is first duplicated, then one copy of every chromosome is drawn to each end of the cell. Then, when the cell divides, each daughter contains exactly the same genetic compliment as the parent cell. Meiosis, on the other hand, is a two stage process, ultimately producing four cells. In the first division, the chromosomes are not duplicated; rather the paired chromosomes line up together (remember, all chromosomes are paired in diploid cells) and one of every pair is drawn to each end of the cell. The daughter cells now contain only half the genetic material of the parent cells (one chromosome from each pair), and are called haploid cells. The second stage of meiosis proceeds similarly to normal cell division, with each chromosome being duplicated before division occurs. Thus meiosis produces four haploid cells, two of them containing one half of the parent's original DNA, and the other two the remaining half. In the female, three of these four cells contain the genetic material and little else; the majority of the cytoplasm, or cell fluids, is retained by the fourth cell, which becomes the egg. The other three cells, called polar bodies, are generally reabsorbed into the female's body.

In AP, the second polar body -- the daughter cell produced along with the egg in the second stage of meiosis -- acts like a sperm and re-enters the egg. Essentially the egg fertilizes itself! As this polar body contains identical genetic material to the egg, having been produced by normal division of an already haploid cell, the resulting diploid cell has only half the genetic diversity of the female's original cells. Thus fewer bands appear in the DNA fingerprint of the offspring.

So why are all the viable offspring males? In most mammals, sex is determined by the X and Y chromosomes, two of which constitute a pair. A pair of X chromosomes and the individual is female; one X and one Y and the individual is male. (As the mother has only X chromosomes -- generally, a YY combination isn't possible, and wouldn't be viable if it were.) In those diapsids (including birds, lizards, and snakes) where AP has been described, females have dissimilar sex chromosomes (ZW), while males have two copies of the same chromosome (ZZ). In AP, if the egg and the second polar body each contain a Z chromosome, when they are combined, a male offspring will be produced. If they both contain a W chromosome (a 50% chance), the egg will be non-viable (WW). This is what causes the high proportion of infertile eggs in AP parthenogenesis.
 
Old 12-03-2004, 06:16 PM   #19
Serpwidgets
Quote:
to my horror I've just discovered one of my 20 month old Hypo female is gravid - she too has never been with a male. She is with a sunglow female the same age - she has been probed and popped and she is no doubt a female. Neither of them have been with males.
There's "pretty sure" and "very sure."

IMO the only "I'm really sure" sexing methods are:

Male: if you see it evert its own hemipenes or watch it put one in another snake, it is a male.

Female: if you see it lay eggs, it is a female.

Probing and popping are fallible. Everyone mis-sexes snakes or ends up with mis-sexed snakes at some point. This is why "murphy's laws" as applied to breeding will always include "the male you raised up for three years is a female" and things to that effect.
 
Old 12-03-2004, 08:18 PM   #20
chausies
Quote:
Male: if you see it evert its own hemipenes or watch it put one in another snake, it is a male.


Female: if you see it lay eggs, it is a female.
Not always

I had a mini-lop rabbit that had visible testes. He was mis-sexed many times by both the pet store and the previous owner. When they gave the bunny to me they thought it was a female, but when I received him he had obvious testicles. I bred him to a white dwarf female twice, she had a litter each time (all healthy babies.) Many months later, I found another male had gotten into "Clover's" cage. I don't remember what the gestation for bunnys is anymore, but it was about a month later and Clover was found delivering 4 baby bunnies breech. None of the babies survived, but they were all full-term. Poor Clover.

I also had a turkey that was male/female. He bred the girls AND laid eggs, he had a distinct "beard" and other typical male traits and he was sexed as a male when he was younger. (None of the eggs that he layed were fertile - but then he was never mated by a male turkey either, he just layed non-fertilized eggs. And I don't think we ever tried to incubate any of the eggs from the female turkeys bred by him, but I would have to ask my mom if she remembers raising any babies from those turkeys.)

It is EXTREMELY rare for an animal to be both male AND female AND reproduce as both. But hermaphrodites are not so rare that you would never see one, if you have enough animals in your lifetime you are pretty much sure to have a hermaphrodite at some point, even if you do not recognize it as such. And if this happens with mammals sometimes, I can only imagine how often this would happen with reptiles. I have heard that on farms, when an animal is born male and female, they cull/kill it for reasons including: if it breeds as a female, it is more likely to suffer and die during pregnancy/birthing and is less likely to produce enough milk. Wierd that it happens frequently enough for farmers to print recommendations for the disposal of those animals.

charlene
 

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