A freshwater fish species, Oryzias latipes, has individuals with four body colour patterns, as shown in Table 5.1. phenotype red white red with black spots white with black spots Table 5.1 body colour pattern Two unlinked genes determine the body colour patterns shown in Table 5.1. One gene controls whether the body colour is red or white: • dominant allele R = red • recessive allele r = white. The other gene controls whether black spots are present or not present: • dominant allele B = with black spots • recessive allele b = without black spots. A fish that is homozygous recessive at both loci is white. Genetic crosses were carried out to investigate the inheritance of the four different body colour patterns. Males that were red with black spots, and homozygous at both loci, were crossed with females that were white. The F1 offspring were all red with black spots. These F1 offspring were then crossed to produce the F2 generation.