Corn Snake Genetics

[Asian Jon]

Recently I have been reading about corn snake genetics on this site:

http://www.pitt.edu/~mcs2/herp/genetics.html

It says that genotypes for normal corn snakes are RrBb, RRBB, RrBB etc...

My question is what do the genotypes look like for hypomelanistic motleys, blizzards, lavender etc...

Any help will be very much appreciated.

Jon

[vanderkm]

Quick answer is - whatever you want to designate them as!! There are some conventions in naming genetic alleles in corns, but not all are agreed to and many people would disagree with the designations used here. Though not strictly correct, the capital letter is usually used to represent the normal dominant gene and the small case letter for the recessive mutant gene, as is done here.

The author of this site has designated melanin pigment to be B for normal melanin and b for amel. He has used R for the normal allele of the gene for erythrin (red) pigment and r for the recessive (anery A - no red). This allows him to complete a Punnett square and illustrate how these genes work to produce snow, anery and amel corns.

Basically you can choose any letter you want with a capital form to designate the dominant form and the small letter for the recessive form - you could use L and l for lavender mutation, C and c for the charcoal anery that combined with amel gives you blizzards. These letters are just tools to help follow the sorting that happens randomly when parents carrying them are paired up.

Tim has a great genetics primer on his site in the FAQs at http://www.cranwill.com/ . Another site that covers a lot of corn genetics is Serpwidgets site at http://www.serpwidgets.com/Genetics/genetics.html .

If you designated the lavender and charcoal as above a snake that was blizzard would be homozygous recessive for amel (bb) and charcoal (cc), so would be bbcc. This doesn't indicate it's status for anery A (the R/r gene above) which could be any of RR, Rr or rr (though I seem to remember that if it is rr the anery A will mask the charcoal and the babies will look snow instead of blizzard).

The same sort of conventions apply for other single recessive genes, but get much messier when you start dealing with hypo (because there are at least four different genes that produce this effect independently) and things like striped and motley which opperate as different versions of the same allele.

I have actually resorted to cheating on the cornsnake genetics stuff and use Mick's progeny predictor - a free download that allows you to choose what morph the parents are, what their hets are and it gives the predictions on the progeny. Great program from http://mywebpages.comcast.net/spencer62/cornprog.html

mary v.

[Asian Jon]

Thanks a lot for your help! I had to read it over many times to fully understand it. I think I am finally getting this genetics stuff hehe. With a bit more research I will clear up more things that are unclear to me.

Serpwidgets' site is great. It is very detailed, yet easy to follow. Thanks for the link.

Jon