<P> An absolute fitness larger than 1 indicates growth in that genotype's abundance; an absolute fitness smaller than 1 indicates decline . </P> <P> Whereas absolute fitness determines changes in genotype abundance, relative fitness (w (\ displaystyle w)) determines changes in genotype frequency . If N (t) (\ displaystyle N (t)) is the total population size in generation t (\ displaystyle t), and the relevant genotype's frequency is p (t) = n (t) / N (t) (\ displaystyle p (t) = n (t) / N (t)), then </P> <Dl> <Dd> p (t + 1) = w w _̄ p (t) (\ displaystyle p (t + 1) = (\ frac (w) (\ overline (w))) p (t)), </Dd> </Dl> <Dd> p (t + 1) = w w _̄ p (t) (\ displaystyle p (t + 1) = (\ frac (w) (\ overline (w))) p (t)), </Dd>

The fitness of an individual is measured by