Fisher's geometric model
Fisher's geometric model (FGM) is an evolutionary model of the effect sizes and effect on fitness of spontaneous mutations proposed by Ronald Fisher to explain the distribution of effects of mutations that could contribute to adaptative evolution. == Conceptualization == Sometimes referred to as the Fisher–Orr model, Fisher's model addresses the problem of adaptation (and, to some extent, complexity), and continues to be a point of reference in contemporary research on the genetic and evolutionary consequences of pleiotropy.