Formal Test of the Model
By spring 1999, I had sufficient numbers of offspring (more than 350 individuals) from various crosses to test for a model of incomplete dominance (Russell, 1990). the results of our statistical tests showed strong support for this mode of inheritance (Ihle, Schuett and Hughes, 2000). Therefore, with respect to wild type, the salmon trait shows incomplete dominance and thus occurs in two forms: a heterozygous state (salmon) and a homozygous state (super salmon).

Because the salmon trait is dominant, when it occurs in the heterozygous state it is expressed, although by way of one gene. In cases where a trait is inherited recessively, such as albinism in boas, individuals expressing the heterozygous state are identical in appearance to wild-type individuals.

Conclusions
Certainly, working on the salmon boa project has been an exciting challenge for me during the past eight years. In 2001, I produced offspring from crosses involving salmon boas heterozygous for albinism to generate six different-appearing types within a single litter: normal, salmon, super salmon, albino, salmon albino ("sunglow") and, possibly, super salmon albino ("super sunglow").

Furthermore, in crosses that involved an albino male to several salmon females heterozygous for albinism, I produced four different looks: normal, salmon, albino and sunglow (super sunglows cannot be produced from this particular cross).

In the next few years, I intend to cross other color and pattern mutations into my salmon and sunglow bloodlines - certainly the range of new looks that will be produced form these crosses is all part of the excitement of breeding boas in the 21st century! Few snakes in herpetoculture have as much variation in color pattern as boa constrictors, and the future looks promising and even more variation is yet to be demonstrated.

References
Ihle, R. N., Schuett, G. W. and Hughes, K. A. 2000. "Salmon: a new autosomal mutation demonstrating incomplete dominance in the boine snake Boa constrictor." Journal of Heredity, 91: 254-256.

Porras, L. W. 1999. "Island Boa Constrictors (Boa constrictor)." Reptiles, 7(12): 48-60.

Russell, P. J. 1990. Genetics. Second edition. Scott, Foresman and Company, Boston, MA.

This article is copyrighted by Reptiles Magazine ©2002 All Rights Reserved.

Back

1-2-3-4-5-6