Reptile & Amphibian Forums

Your odds may be better than you think. Let's take a look at a het albino X het albino breeding. Each egg has a 25% chance of being albino. If there are 4 eggs, you might think that you have a 25% chance of getting an albino. However, this is not true. You actually have a far better chance of hatching an albino. The odds that you do not hatch an albino are (.75)(.75)(.75)(.75) = 31.6%, so the odds that you hatch at least one albino are 68.4%. If there were 3 eggs the odds would be 57.8%, 5 eggs 76.3%, 6 eggs 82.2%, 7 eggs 86.7%. I guess the point of this post is to let you know that your odds may be better than you think.

That's interesting. I'd never thought of it that way before. Gives me more hope that I'll produce at least one albino from my het pair in about three years. I can't wait. Then I'm going to mix in my spider male and get some spider albinos. Once again, thanks for that, quite interesting to look at it that way.

No problem. I knew majoring in math would come in useful at some point in life lol.

Good stuff and a very great way to look at it...that each egg, while statistically having roughly a 20% - 30% chance of producing a visual, that this chance is additve with each egg and that the more eggs you have, the better your chances of producing a visual. Based on an average clutch of 3 to 8 eggs or so. Very nice!

On the not so positive side, when people say you need to breed a het twice to disprove them as carrying a specific gene. What are the odds of your snake actually carrying a certain gene if they lay 3,4,6...etc eggs and all appear to be normal. Also, how high should someones hopes be (statistically) going into the next year if their snake lays 3,4,6,etc eggs and you are waiting for them to hatch?

that actually makes no sense to me.

the way I understand the odds in getting a visual morph isn't really based on clutch size. Each embryo has the same chance of being a het carrier, or visual morph or just a plain old wild type normal.

Thus when using Punnett Squares (or whatever they are called), it just gives the probably results of combining genetic material. Each 'baby' gets one half of its genes from each parent, thus if each parent carries a normal gene at that location, and a mutant gene, then the baby have a certain chance of inheriting the mutant gene from both parents, thus producing a visual morph.

Punnett squares give the nice 25% chance out of 4 eggs to be the visual mutation.

But there is no guarantee that for every 4 eggs, you will have one normal, two hets and one visual morphs, you can have all visual morphs in a 4 egg clutch or even an 8 egg clutch. This is rather more rare than having one out of 4, but certainly not impossible, same as having all normals or all hets, or a mix of hets etc.

Not sure where that .75% to be albino came from though..
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PHLdyPayne

The Punnett square is the odds for each egg, not the clutch. Basically it shows all the possible gene combinations one egg can get. People often take it as a clutch distribution but it’s really a per egg distribution of possible genetic outcome.

Per the original post, the 75% chance is the chance of each egg from het X het NOT being an albino. Since it either is an albino or it isn't the combined chance is 100% so 100% - 25% = 75%. Basically you combine the odds of each one not being an albino to find the chance of getting no albinos (less likely with more chances/eggs) and subtract that from 1 to get the chance of getting 1 or more.

I actually think that looking at it that way makes most people think they have worse odds to get a visual. A lot of people incorrectly think that if you have a 4 egg clutch you will get 1 visual. This year I hatched 9 eggs from het x het breedings and got zero visuals. I will always use visual males for all of my projects from here on out. At least then if the odds screw me I will have 100% hets and avoid the impossible to sell 66% het males.
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John Vandegrift

Wow, you really defied the odds of probability. You had a 99.9996185% chance of getting at least one visual. Either one of your animals was not 100% heterozygous or you were extremely unlucky.

9 eggs from het to het I'm only figuring about 92.5% chance of at least one homozygous. Not a good sign but could just be bad luck to het 7.5% odds.

I am not worried about the genetics of any of the hets. I just have horrific luck.
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John Vandegrift

yup, my error, 92.5%