Add a brown eyes cross in the Punnett Square below for practice: Mother genotype (Bb) in the top squares, father genotype (Bb) in left side squares. B B. I b

My answer is the genotypes are BB, Bb, Bb, and bb.

Explanation:

I attached a photo of the punnet square after crossing the genotypes Bb and Bb.  Crossing the B on top with the B on the side results in the genotype BB.  Crossing the b on top with the B on the side results in Bb.  The genotype that results is written in the box that connects the row and the column (such as top row and left column results in BB).  

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).