In genetics, the dash symbol (–) is a "wild card" that stands for either the dominant allele or the recessive allele; for example, a– means the individual has either the genotype aa or aa. two genes that undergo independent assortment affect fruit color in summer squash. each gene has two alleles, one of which is dominant for fruit color. genotypes of the form a– b– and a– bb have white fruit, genotypes of the form aa b– have yellow fruit, and genotype aa bb has green fruit. what ratio of white : yellow : green is expected from the cross aa bb × aa bb?