Genetics 101 ????

To all of you genetics gurus I have a question.

What genetic combinations would give you the best outcome for different morphs. Trying to help build a collection for a colleague's high school genetics program for his advance biology class.

I am still figuring out the genetics stuff and I understand that a heterozugous carrier will appear normal masking the recessive trait. But can a homozygous animal carry hetrozygous genes?

But I would really like to know what the best combos would be to have multiple offspring morphs. I am planning on going to the FIRE show and I am creating a shopping list.

While on the subject of shopping is it better to get juv, yearling or adults.

As to what combinations would give you the best outcome for different morphs would depend on how much you are willing to spend and what you are able to find. The easiest to obtain and the cheapest would be a normal double het amel and anery X snow. The resulting offspring would be normal, amel, anery and snow. Of course, adding other traits into the mix would give you even more of a variety. If you could find a normal quad het amel, anery, hypo and motley X a snow motley homozygous hypo, You would be adding hypo and ghost to the color scheme plus the chances of getting motleys in each color morph.

A snake that is homozygous for a trait, for example caramel (cc), is carrying 2 recessive genes resulting in the caramel color. That snake cannot carry a dominant gene (C). The same snake CAN be heterozygous for other traits, such as hypo and motley (ccHhMm).

As to what age is best to buy...again depends on how much you want to spend and how soon you want to breed. Older snakes are more established, reducing your chances of losing one, adults are ready to breed - no waiting (except for the breeding season), but older snakes are usually more expensive and your chances of getting the exact morphs and sex you want is less likely than with hatchlings.

lnwolf88 said:

I am still figuring out the genetics stuff and I understand that a heterozugous carrier will appear normal masking the recessive trait. But can a homozygous animal carry hetrozygous genes?

Click to expand...

If an animal is homozygous for something, by definition it is not possible to be heterozygous for the same thing. It's an either/or situation.

If you have two coins laying on a table, they are either:

1- Heads/Heads
2- Heads/Tails
3- Tails/Tails

1 and 3 are homozygous. 2 is heterozygous.

That is, "homo" means same, and "hetero" means different.

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"Can a homozygous animal carry heterozygous genes?" Hmm... I think I know what you're asking. Break down the "genotype" into a bunch of pairs of coins. Say you have 2 pennies, 2 nickels, 2 dimes, 2 quarters. If the pennies are both on heads, can you have a nickel on tails? Certainly.

You could say that the "Amel" trait is determined by the pennies. Anery is determined by the nickels, Motley by the quarters, and Hypo by the dimes.

The pennies have no relationship to--or dependency on--the other coins... this is how cornsnake traits intermingle: they are independent of each other.

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The best variety could be achieved by having as many "het X mutant" crosses in the same pair as possible. That is, have one parent heterozygous for a given trait and the other parent expressing (homozygous for) that same trait. For example:
Hypo motley snow X Normal het hypo/motley/amel/anery
or
Ghost het amel/motley X Amel motley het anery/hypo
or
Hypo motley het amel/anery X Snow het hypo/motley
etc.

All of those crosses (and any of the 16 possible ways to do that cross) give half hypos, half motleys, half amels, half anerys.

Yeah, that's a lot of halves, eh? But they are independent so you get a 16 way split of:

Normal
Anery
Amel
Snow
Motley
Motley Anery
Motley Amel
Motley Snow
Hypo
Ghost
Amel *
Snow *
Hypo Motley
Ghost Motley
Motley Amel *
Motley Snow *

* - hypo is present but not necessarily visible or detectable.

The biggest trick is actually finding the genotypes you want...