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BoaMorph
at Wed Nov 28 22:57:24 2007 [ Email Message ] [ Show All Posts by BoaMorph ]
So what do I get when I cross my Paradigm boa to my Sharp-sunglow boa? Such multi-trait crosses are where the genetics start to get REALLY fun, and have kept me up late many nights puzzling out the offspring genotype/phenotype ratios from all kinds of crazy hypothetical crosses.  For now we will start with the relatively simple example posed above.
Please note that we have made one change to the terminology used in our previous posts (see our four Paradigm posts of November 18th) courtesy of some much appreciated feedback from Paul Hollander. We were unaware that a locus is customarily named with a letter or combination of letters based on the first identified mutant-allele. In this case, I believe the genetics of the Sharp-albino were worked out before the Caramel-hypo, and so the locus name should really be something like "s" or "as" based on the mutant Sharp-albino allele. We also had purposely simplified the notation for the multiple allele series which normally calls for using the same base character(s) (in this example "s" or "as" ) but with different superscript letters or symbols representing the various alleles (a plus character superscript symbolizes the normal allele and no superscript character is given to the first mutant allele of the series). Obviously, all these symbols can quickly become rather cryptic for those who are not accustomed to working with this notation. As such, we will continue to use the simplified notation of our previous examples and, though technically the locus name should be something like "s" or "as", we will at least refer to it now as the Sharp-albino locus rather than the Paradigm locus as we had in our previous posts, with our sincere apologies to geneticists everywhere.  We think that these simplifications will help the reader to more easily understand the true focus of these posts, which is how to correctly determine the expected genotypes, phenotypes and ratios that will be produced from a given test cross that involves the Paradigm trait. For those interested in seeing firsthand just how simplistic our routine hobbyist-level discussions of boa genetics are, please see Mr. Hollander's response to one of our November 18th posts in which he provides a link to a Jackson Lab web page titled "Rules for Nomenclature of Genes, Genetic Markers, Alleles, and Mutations in Mouse and Rat" - genetics is NOT a simple science!
Now back to the fun! So what do I get when I breed my Paradigm to my Sharp-sunglow? Such crosses involving multiple unrelated traits can be evaluated using a Punnett square (4x4 for two traits, 6x6 for three traits, etc.), but it gets very tricky to correctly distribute the alleles in the parent's boxes of the square as the square gets larger and it is easy to make mistakes. It is actually simpler to use a statistical approach, and the good news is that you don't need to know anything about statistics to use it!
In considering our Paradigm to Sharp-sunglow test cross we are dealing with two loci, one being the Sharp-albino locus, and the other which we will call the Salmon-hypo locus (to clearly distinguish the Salmon-hypo trait from the Caramel-hypo trait - and again, not a technically correct name for a locus, but this will help prevent us from getting lost in the lingo). The combinations of alleles at the Sharp-albino locus and at the Salmon-hypo locus are unaffected by each other, and so we can analyze the allele combinations at these loci independently using the familiar 2x2 Punnett square as shown below.
In order to determine how these traits will combine in the offspring, we must merge the above results for these two loci using a simple statistical method. The four arrows in the diagram below indicate the four possible combinations of results at these two loci.
The frequency of each of the four possible combinations of results is obtained by simply multiplying the ratios together as shown below.
This process can be further simplified by creating a well-organized table as shown below. The possible outcomes for the Salmon-hypo locus are shown in the leftmost column. In the second column, the possible outcomes for the Sharp-albino locus are repeated for each possible outcome in the previous column. We then simply multiply all of the boxes across from left to right to obtain our four possible outcomes and associated frequencies.
Note that this is a relatively simple example in that there are only two possible outcomes at each of the two loci. Additionally, each of the four resultant genotypes has a unique phenotype, and so the genotype and phenotype ratios are identical (in this example we did not need to consider the significance of whether we multiplied genotype frequencies or phenotype frequencies because they are the same). In some future posts we will provide additional examples in which the genotype ratios differ from the phenotype ratios, and for which there are more than two loci involved in the test cross.
So where's the fun? Personally, I have had a BLAST playing around with every conceivable combination of the Paradigm with other traits! Motley Paraglow, anyone? How about a Paraghost, and will it be distinguishable from a ghost? The possibilities are mind-boggling! Playing with the genetics isn't your thing? Then consider that the REALLY cool thing with the Paradigms is that you can produce completely new visual morphs with first generation crosses to morphs that exist NOW!
Consider our example above - by crossing a Sharp-sunglow with a Paradigm we produce a litter in which fully one fourth (on average) of the offspring will be Paraglows, a visual morph that did not previously exist (until Mike Weitzman produced it this summer, that is - please visit www.BasicallyBoas.com to view some photos of this AWESOME beast!). Sure beats the heck out of breeding a het. albino motley to a double het. sunglow hoping for the 1 in 16 sunglow motley - LOL!!! That's not to say that the sunglow motley isn't a worthy endeavor - we're actually hoping that this will be one of our successful breeding trials this year! But the comparison shows the enormous potential with the Paradigms to produce good numbers of new visual morphs without having to wait for hets to mature and breed to finally see something new!
Again, all questions, comments and feedback are welcome. More examples to come soon. Thanks for looking!
Steve Reiners
www.BoaMorph.com
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 Paradigms #4 - Multiple Traits - BoaMorph, Wed Nov 28 22:57:24 2007
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