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Posted by Paul Hollander on August 12, 2000 at 10:24:24:
I've compiled a list of genes for the corn snake which I'm posting for comments and criticism. At the least, it may help identify some of Rich Zuchowski's pictures. 8-)
Paul Hollander
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A Partial Gene List for the Corn Snake
Common Name: Corn Snake
Scientific Name: Elaphe guttata guttata
Number of Loci: 9
Note: Unless specified otherwise, recessive means recessive to the wild type allele, dominant means dominant to the wild type allele, and partially dominant (or codominant) means partially dominant (or codominant) to the wild type allele. Symbols follow the Rules and Guidelines for Genetic Nomenclature in the Laboratory Mouse (see the link).
Locus Symbol: a
Number of Alleles: 2
+ = +a = wild type allele
a = amelanistic. Recessive. A defective tyrosinase enzyme is unable to form black pigment. The eyes are pink. Red pigment is unaffected.
Locus Symbol: ax
Number of Alleles: 2
+ = +ax = wild type allele
ax = anerythristic. Recessive. Prevents red pigment from being formed. Color is shades of gray from white to black because the amount and distribution of black pigment is unaffected. Older adults develop yellowish tints.
Locus Symbol: ca
Number of Alleles: 2
+ = +ca = wild type allele
ca = caramel. Recessive (probably). Prevents some of the red pigment from being formed but does not entirely eliminate it. Black pigment is not affected.
Locus Symbol: ch
Number of Alleles: 2
+ = +ch = wild type allele
ch = charcoal (Sometimes called anerythristic type b.). Recessive. Prevents red pigment from being formed. Color is shades of gray from white to black. Older adults do not develop yellowish tints, and there are a few other subtle differences from anerythristic.
Locus Symbol: hy
Number of Alleles: 2
+ = +hy = wild type allele
hy = hypomelanistic. Recessive. Reduces the amount of black pigment but does not entirely eliminate it. Red pigment is not affected.
Locus Symbol: la
Number of Alleles: 2
+ = +la = wild type allele
la = lavender. Supposed to be recessive to normal pigment. I'm not entirely sure of how it changes the snake's appearance. See the Serpenco web page.
Locus Symbol: mo
Number of Alleles: 3
+ = +mo = wild type allele
mo = motley. Recessive. The blotches are run together, and the checkers on the belly do not appear so that a uniform ventral coloration is produced.
most = striped. Recessive. The blotches are converted into four stripes and the checkers on the belly do not appear so that a uniform ventral coloration is produced. Motley is partially dominant to striped because a heterozygous motley/striped (mo//most) corn snake has a pattern that is approximately intermediate between a motley (mo//mo) and a striped (most//most) corn snake.
Locus Symbol: pb
Number of Alleles: 2
+ = +pb = wild type allele
pb = plainbelly (likely to be called blood red). Recessive. The blotched pattern is diffuse instead of being sharply defined. The normal dark checkering on the belly is absent. This mutant was found in the blood red variety combined with a dorsum that is a dark red color that is redder than normal. The pattern effects on the back and belly are supposed to be from a single mutant that is recessive to normal. Nobody seems to know whether the color is caused by one or several mutants and how it is inherited. Outbreeding to increase fertility is likely to lose some of the extreme red color.
Locus Symbol: zi
Number of Alleles: 2
+ = +zi = wild type allele
zi = zigzag. Recessive. Converts the blotched pattern into a more or less zigzag pattern. The belly is checkered, unlike motley.
Unknown Inheritance
Miami phase. The inheritance seems to be unknown. Ground color is gray (sometimes with yellowish tints), and the bloches are red.
Okeetee. Snakes with a particularly bright red-orange ground color and relatively wide black borders around the dorsal blotches. Named for the Okeetee Hunt Club in South Carolina, where such snakes are common.
Piebald. The hide is patched with variable amounts of white. This condition is not present at birth but appears later in life. It may be the result of an autoimmune disease.
Mutant Combinations
Most of the corn snake color and pattern varieties were produced by combining two or more mutants. For example, snow is a combination of amelanistic and anerythristic (a//a ax//ax). Blizzard is believed to be a combination of amelanistic and charcoal (a//a ch//ch), though there may be something else there, too. And ghost is a combination of anerythristic and hypomelanistic (ax//ax hy//hy).
Hybrids
Creamsicle. Amelanistic in a snake with both corn snake and Great Plains rat snake ancestry. Lighter orange than in an amelanistic corn.
