According to Williams' 1966 book Adaptation and Natural Selection, he essence of the genetical theory of natural selection is a statistical bias in the relative rates of survival of alternatives (genes, individuals, etc.).
Segundo o libro de Williams de 1966 Adaptation and Natural Selection, a esencia da teoría xenética da selección natural é un nesgo estatístico nas taxas relativas de supervivencia de alternativas (xenes, individuos etc.).