The section titled Gene/Allele confusion is very confusing.

"we simply don't know how many genes are being affected by each characteristic"


Not really sure what you mean here.
First of all in traditional genetics genes influence traits, not the other way around.

We know that traditional albinism is caused by one gene. There are other forms of albinism caused by different gene loci. They are usually called something different like lavender albino or caramel albino etc.

It is possible that two different traditional-looking albinos of separate lineages are mutants of different gene loci. But you could easily distinguish these two possibilities by using the recessive complementation test.

If they were slightly different mutations of the same gene-->A1 (a1a1) x A2 (a2a2)-à a1a2 (all Albinos)


If the mutations were of separate gene---> A1 (a1a1 A2A2) x (A1A1 x a2a2)à A1a1A2a2 (A normal looking animal that would be heterozygous for both albino genes)

Furthermore, when a base morph is discovered initially. You can determine whether that particular genetic aberration is caused by one or two genes. For example, let’s say you find a white looking snake. You breed your snow to a normal looking bp (the F1 generation). All offspring in the F1 generation are normal looking. At this point, your putative genetic aberration is either non-genetic, a one gene-recessive, or possibly a multi-gene recessive. You can begin to distinguish among the possibilities by crossing two of the F1 offspring. If after years of nice large clutches you find ~25% of the offspring to be white while ~75% are normal, you’ve found a one gene recessive trait.


Now let’s say you get different results from your F1 x F1 cross. Your amazed that in your first clutch you get a normal looking offspring, albino offspring, and axanthic offspring. Furthermore, after patiently waiting for your F1 parents to be ready to breed again you repeat the cross. This time you get 1 white snake almost identical to the original founding parent. After decades of work and recording keeping you find that you get ~56%(9/16) normals, ~18% albinos (3/16), ~18% (3/16), and 6% (1/16) white looking snakes. This is the classic two gene or dihybrid ratio of 9:3:3:1.

Now the second scenario was made up, but it was based off of the designer morph snow. This is exactly the kind of thing that would happen if you found a snow in the wild and wanted to prove it genetic!

While your unlikely to find a snow or two gene aberrant in the wild, the scenario illustrates that you can distinguish a trait that is caused by one gene from a trait that is caused by two or more genes using classic Mendelian analysis.

One gene recessive-->3:1 phenotypic ratio

Two gene recessive--->9:3:3:1 phenotypic ratio