When done with this article don't forget to take our Punnett Squares Interactive Quiz to see how well you know punnett squares.
Punnett squares are simple for one characteristic or one Locus such as the A Locus (agouti) in a rabbit. However, this would certainly not meet the needs for predicting possible offspring colors for a litter. So lets advance now to a dihybrid cross or two Locus cross. Lets take a buck that is Agouti carrying self (Aa) and also Black carrying Chocolate (Bb), and breed him to a doe with the same genotype (AaBb).
We need to pass to the kit one gene from each Locus. The buck could pass on four different gametes. He could pass on an A gene, and from the B locus he could pass on either an B or a b. In other words he could pass on either AB or Ab. He also could pass on the a gene and either of the B genes, or aB or ab. The four gametes would be AB, Ab, aB or ab. The same is true for the doe. As you can tell the punnett square will be much more complex, have a total of 16 boxes.
We then add one possible allele above each column of our table for the buck, and one possible allele to the left of each row for the doe.
Now we carry across the rows for each of the doe alleles and down each column for the buck alleles. Remember keep things alphabetical and the dominant gene is listed first.
As you can see 9/16 offsprings (56.25%) will be black agouti, 3/16 (18.75%) black self, 3/16 (18.75%) chocolate agouti, and 1/16 (6.25%) would be chocolate self.
Of course this can get increasingly difficult. We could then take into account three Loti as opposed to two. Or we could go as far as all of the five major color genes for holland lops. Check back in a few days and we’ll look at more advanced squares and let you take a quiz to see how much knowledge you gained in determining colors by using Punnett squares.Rob Usakowski