We examined dorsal pigments and ventral patterns in the Florida Cottonmouth, Agkistrodon piscivorus conanti, in the Alapahoochee watershed, Lowndes County, Georgia. Cottonmouths darken as they age; but the process has not been quantified in the literature. Thus, we examined both graphically and statistically changes in dorsal color pattern that occurs when snout vent length (SVL) increases as well as discrete patterns involving splotching and block-like patterns, and cream to white coloration on the ventral surface, which indicate underlying genetic factors. Snakes with SVLs between approximately 26.8 and 120.3 cm possessed an array of dorsal colors involving white, tan, dark brown and black. Snakes greater than 60 cm SVL had fewer dorsal white and tan colors with dark brown and black being the primary remaining colors in snakes up to 120 cm. Nonparametric regression analysis provided graphic representation of the process, which is confirmed by correlation analyses. Ventral color patterns show discrete relationships involving the occurrence of all white coloration and splotch and block patterns involving dark pigments. If a block pattern was present, then a splotch pattern was less likely to be present and vice versa regardless of SVL. Correlation analysis supports the observed ventral patterns. Possible genetic explanations would be a single locus with incomplete dominance expressed by one allele resulting in all white or no dark blocked pattern, another allele resulting in incomplete dark bars, and heterozygotes showing only partial bars or blotches primarily on the rear location anterior to the vent.
Bechler, David L.; Kirkley, Joseph A. Mr.; and Elder, John F.
"Dorsal and Ventral Color Patterns in a South Georgia Population of Agkistrodon piscivorus contanti, the Florida Cottonmouth,"
Georgia Journal of Science, Vol. 75, No. 2, Article 13.
Available at: http://digitalcommons.gaacademy.org/gjs/vol75/iss2/13