Answer
Through the different phenotypes each gene represents.
Work Step by Step
A gene can have more than one allele, as apparent by the white eyed fly mutation that has 5 alleles.A gene can have different alleles that come about as different phenotypes, and the function of the gene can be compromised depending on where the gene is located on the chromosome. Even an allele that has no functional product (null allele) will have a different phenotype depending on its location on the chromosome.
