I don't know if this is correct but Evolution can be defined as biological change over time. As the ff (furless) individuals die off, the gene frequency of both the F and f alleles changes, as there are more F alleles in the population. As the genotypic frequency within the population changes over time, the phenotypic variation also changes. Genotypic and phenotypic change is “biological change”. As biological characteristics of a population change over the generations, the population evolves.