>I was wondering if anyone could recommend either a site or book that deals with the genetics of corns in some detail. I teach school and am using corns as a part of my genetics unit and have some questions as to the specifics of how the color and pattern genes work in corn snakes. What genes are dominant, does codominance occur and when?
AFAIK, all corn snake mutant genes analysed so far have turned out to be recessive to the normal allele. And all the mutants except striped and motley are independant. I've been shown corn snakes from a striped x motley cross, and all of the babies had patterns roughly intermediate between the parental patterns. This indicated to me that the two mutants were alleles and codominant to each other as well as being recessive to the normal allele.
The single most useful book on corn genetics is Michael McEachern's Color Guide to Corn Snakes. Used copies cost around $6 through Amazon. It's a bit dated now, but not too badly. Main thing I have against it is the symbols in the genetics chapter -- b for amelanistic and r for anerythristic. Bern Bechtel used a for amelanistic and ax for anerythristic in a 1989 paper in the Journal of Heredity, which gives his symbols priority by date. Bechtel also followed generally accepted symbol guidelines better than McEachern.
Bill and Kathy Love's The Corn Snake Manual has some genetics material.
H. Bernard Bechtel's Reptile and Amphibian Variants: Colors, Patterns, and Scales is the best overview for all reptiles and amphibians. BTW, Bechtel produced the first captive bred amelanistic and motley corns.
And as another suggested, Mick Spencer's corn snake progeny predictor.
Schaum's Introduction to Genetics is a good, inexpensive introduction to the subject of genetics. IMHO, the chapters trying to teach genetics in McEachern and Bechtel's books are the poorest in each book. (This opinion is based on having taken a general genetics course in college and working for 5 years in a college genetics laboratory.)
>I have the following pairs to breed as a part of the project:
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>Normals(het for Lav, and snow)
Main thing I have against Mick's progeny predictor is that it uses terms like "het for snow". This gives a student the impression that snow is a single mutant. "Heterozygous for lavender, amelanistic, and anerythristic" would be better for the student.
IMHO, anybody who routinely uses the Punnett Square for two or more loci is a masochist. The branching system (AKA forkline, arithmetic method, etc.) is much superior.
Paul Hollander
