Price, George R. 1970

Price, George R. 1970. Selection and covariance. Nature vol. 227 (520-521). "Preliminary communication describing applications to genetical selection of a new mathematical treatment of selection in general.

Gene frequency change is the basic event in biological evolution. The following equation (notation to be explained), which gives frequency change under selection from one generation to the next for a single gene or for any linear function of any number of genes, at any number of loci, holds for any sort of dominance or epistasis, for sexual or asexual reproduction, for random or not random mating, for diploid, haploid or polyploid species and even for imaginary species with more than two sexes

∆Q = Cov(z,q)/ż

The equation easily translates into regression coefficient (β_zq) or correlation coefficient (ρ_zq) form

∆Q = β_zq(𝛿_q)²/ż = ρ_zq𝛿_z𝛿_q