Selection coefficient

The following definition of s is commonly used.[1] Suppose that there are two genotypes A and B in a population with relative fitnesses ${\displaystyle w_{A}}$ and ${\displaystyle w_{B}}$ respectively. Then, choosing genotype A as our point of reference, we have ${\displaystyle w_{A}=1}$, and ${\displaystyle w_{B}=1+s}$, where s measures the fitness advantage (s>0) or disadvantage (s<0) of B.