Continued Breeding
As my second-generation boas matured, further critical breeding experiments were planned. Because I now had evidence that the salmon trait was dominant, I performed crosses involving offspring of salmon-to-salmon breedings (both littermates and non-littermates) that were wild type in pattern and coloration.An additional cross was performed to investigate the interaction of dominant and recessive genes that are involved in the same traits, but which might occur at different locations on chromosomes. We obtained an adult male albino boa (Pete Kahl strain) from Dave and Tracy Barker to cross to two second-generation females that were salmon but which had no genes for the albino trait. (Albinism in boa constrictors is a recessive trait that is not sex-linked and thus requires the homozygous condition to be expressed.)
Another cross involved a super salmon male and a salmon female. Since the publication of our paper (Ihle et al., 2000), I have performed several crosses involving super salmon males and females.
As expected, the second-generation crosses involving the wild-type individuals that were th;emselves the pjroduct of salmon-to salmon crosses resulted in offspring that were indistinguishable from the normal, wild-type condition. None produced salmon progeny. Therefore, these crosses demonstrated unequivocally that the salmon trait was not inherited in the recessive fashion.
The crosses invloving the albino male to salmon females resulted in progeny that were either salmon or wild type (50-to-50 raatio), and all were heterozygous for albinism.
A single cross involving salmon boas heterozygous for albinism has been performed by Tracy and Dave Barker and resulted in the first albino salmons and, possibly, an albino super salmon. These boas have been referred to as "sunglow boas."
Lastly, super salmon boas crossed to normal individuals resulted in offspring that were scored as salmon (100 percent), and crosses between super salmon and salmon resulted in offspring that were scored either as super salmon or salmon (50-to-50 ratio).
In the super salmon-to-super salmon crosses that have been performed in my facilities, all babies were scored as super salmon. These crosses verified our suspicions that salmon occurred both as homozygous (super salmon-same gene states) or heterozygous (salmon-different gene states) and thus supported the model o incommplete dominance as th;e mode of inheritance (Russell, 1990).
This article is copyrighted by Reptiles Magazine ©2002 All Rights Reserved.