Posted by:
Paul Hollander
at Mon Jun 11 13:56:50 2007 [ Email Message ] [ Show All Posts by Paul Hollander ]
The basic idea here is correct, but the definition of allele needs work.
Alleles are different forms of a gene. If we call a chromosome the equivalent of a page of text, then each gene is equivalent to one sentence in that page. The wild type or normal allele is a sentence without a typographical error. A mutant allele is the same as the normal allele except it has the equivalent of a typographical error. Different typos in the sentence make different mutant alleles, but they all have the same location in the chromosome (page).
In snakes, each mutant gene has a normal allele and no other alleles. In other words, in this situation, there are two alleles at a given locus (a location in a chromosome). The Kahl albino mutant gene has a normal allele, and the caramel albino has a normal allele. But the Kahl albino and the caramel albino have different loci (loci is the plural of locus).
Sometimes there may be three or more alleles for a given locus. More than two alleles is called multiple alleles. It looks like the Sharp albino could be one mutant allele, the boawoman hypo is another mutant allele, and the normal allele is the third allele. By the way, this idea needs more testing, but it's the best explanation (in my opinion) for the data that's been collected so far.
In mice and other species, over a dozen alleles have been identified at a given locus. However, a single animal can have no more than two of those alleles. But they all could show up in a group of a few dozen animals. 
The point of this post is that while there are cases of multiple alleles, it is not necessary for any two mutant genes to be alleles. In mice, over 50 loci with mutants affecting color and pattern have been identified. With the relativley small number of mutant genes known so far in snakes, it is more surprising to find a case of multiple alleles than not to find one. While I have no doubt that more cases of multiple alleles will show up with time and testing, there is no need for any given case to be multiple alleles.
Paul Hollander
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RE: Normal Albino X T Albinos?? - Paul Hollander, Mon Jun 11 13:56:50 2007
