Proving Dominant Traits

[gsarchie]

but they are both live bearing snakes, so not likely the case here. Either way, cool stuff.

http://home.pcisys.net/~dlblanc/arti...enogenesis.php

[OhhWatALoser]

I have never heard of cases of parthenogenesis occuring in balls, or any snakes for that matter, and there is definitely no way that babies could get genetic material from dad only.

there are a few cases of it happening in boas, bout all I know

[RandyRemington]

Here is a Burmese python case:

http://www.nature.com/hdy/journal/v9.../6800210a.html

I regularly hear of isolated pet ball pythons laying eggs but it's usually someone without the skills/equipment to hatch the eggs and I don't know that any testing has been done if there ever where hatchlings. It’s just too easy to explain as retained sperm. Basically I think if it exists in ball pythons it isn't being found because we aren't looking for it. It would be very messy for the market. I know a breeder who thinks he might have seen it this year and he is considering selling off what was once a favored female ball python and all her offspring because he is worried it might happen again and doesn't want the uncertainty or to be associated with the unpredictable genetics.

I certainly wouldn’t expect that it would be possible for the male to contribute the full set of genetic info but then again I wouldn’t think it would be possible that homozygous spiders never exist at any stage of reproduction. I’ve been hearing scattered reports of heterozygous co-dominant males to normal for the same mutation females producing apparent super/homozygous co-dominant offspring. I think the current industry explanation is a null allele situation on the females side. It would be interesting if we can get to the point where genetic testing is so cheap and available that some of these animals could be tested and compared to their parents to see for sure what is going on.

[RandyRemington]

I really am quite ignorant of the python reproductive cycle. At what point does the egg cell become associated with the follicle? Is ovulation when the egg cell gets paired up with the follicle? The egg cell is already fertilized then, right? Maybe homozygous spider is homozygous lethal before ovulation so only non-homozygous spider fertilized egg cells are available to use up all the available follicles. True, there should only be 66% spider offspring from spider X spider with this scenario but 78% might not be that statistically significant an over represented in this sample size and maybe spider sperm have an advantage in fertilizing egg cells anyway.

[OhhWatALoser]

I really am quite ignorant of the python reproductive cycle. At what point does the egg cell become associated with the follicle? Is ovulation when the egg cell gets paired up with the follicle? The egg cell is already fertilized then, right? Maybe homozygous spider is homozygous lethal before ovulation so only non-homozygous spider fertilized egg cells are available to use up all the available follicles. True, there should only be 66% spider offspring from spider X spider with this scenario but 78% might not be that statistically significant an over represented in this sample size and maybe spider sperm have an advantage in fertilizing egg cells anyway.

if it works anything like humans and I'm remembering high school correctly.... ovulation is when the egg is released to meet with the sperm, so until that point nothing is determined.

[WingedWolfPsion]

I have a male spider that I bred last season, and I got 2 female and 1 male spider from one clutch of 6, and 1 female spider from the other (smaller) clutch.
There was nothing unusual about the ratio or gender breakdown, and clearly male spiders can easily sire more male spiders.

It's a most interesting puzzle!

[paulh]

but they are both live bearing snakes, so not likely the case here. Either way, cool stuff.

http://home.pcisys.net/~dlblanc/arti...enogenesis.php

Excellent article!

As this sort of thing has been found in egg-laying lizards and birds, it seems likely to be able to occur in egg-laying snakes.

I really am quite ignorant of the python reproductive cycle. At what point does the egg cell become associated with the follicle? Is ovulation when the egg cell gets paired up with the follicle? The egg cell is already fertilized then, right? Maybe homozygous spider is homozygous lethal before ovulation so only non-homozygous spider fertilized egg cells are available to use up all the available follicles. True, there should only be 66% spider offspring from spider X spider with this scenario but 78% might not be that statistically significant an over represented in this sample size and maybe spider sperm have an advantage in fertilizing egg cells anyway.

A single egg cell develops inside each follicle in the ovary. Ovulation occurs when the egg cell leaves the follicle. Fertilization occurs after ovulation.

Male spider x female normal produces both spider and normal offspring. So spider sperm can get to the eggs. But are there fewer spider offspring from this sort of mating than from a normal male x female spider mating? Anyone collected any statistics? For that matter has anyone collected statistics to see if there are the same, fewer or more spiders than normals from such matings? If there are statistically less than 50% spiders from spider x normal matings, it would be consistent with the lethal homozygous spider theory.

[paulh]

Paul, so after 25 33% chance possible homozygous animals in a row failed to prove did the breeder decide it's a homozygous lethal mutation? Did ya'll notice about 1/4 bad eggs from the het X het breedings or any infertile possible homozygous animals?

Yes, he decided crested was lethal when homozygous. The odds of getting that string of failures by chance was just too small. He also found that there were fewer crested zebra finches than normals from a crested x normal mating. This was when the results of many matings were totaled.

Part of what I did was to check the finch nests for eggs and nestlings. A clutch averaged 6 eggs. Three babies leaving the nest was considered good results. The other eggs were either infertile or dead embryos. Entire clutches might be abandoned. An egg was approximately 1/4 inch long, so hatchlings were tiny. Dead hatchlings were not recorded. They were lost in the nest material or litter on the cage floor. So we could not zero in on the stage of homozygous crested death. Sometime before feathering out was our best guess, which leaves plenty of time. Sterility in adults did not seem much of a problem.

[WingedWolfPsion]

Paul, while I'm a small breeder, and have produced only a few spider clutches so far, the ratio of spider to normal has been extremely typical--just the same as ratios in lesser and mojave clutches. Sometimes a few more, sometimes less, but usually about the same number of morphs and normals.

I work a lot with the very similar woma mutation, and ratios there are also typical.

This means little, because I know from personal experience how dramatically a single clutch can sway from the average--I got 11 pastels and 2 normals out of a 13 egg clutch from a pastel X normal breeding, once, lol.

[PsychD_Student]

This website will further explain, with different examples, the reason behind these morphs showing more characteristics of incomplete dominance genetics than co-dominant genetics.

http://www.hobart.k12.in.us/jkousen/...y/inccodom.htm

These are short quizes! Haha

http://www.ksu.edu/biology/pob/genetics/incom.htm

http://sciencespot.net/Media/gen_spbobincdom.pdf