Probability of fixation of a mutant gene in a finite population when selective advantage decreases with time.

摘要: ROBABILITY of gene fixation, that is to say, the probability by which a muPtant allele becomes eventually established in population subject considerable interest both and evolutionary genetics. In his pioneering work, HALDANE (1927) showed an infinite individual mutant having selective advantage s can reach fixation with about 2s. Later, more general results were obtained KIMURA (1957) for finite populations based on diffusion models (see also 1964). His formulae used ROBERTSON (1960) develop theory limits artificial selection. A still but quite simple formula was &MUM (1962) as function mean (Mao) variance (V,,) rate change frequency per generation. The general, far single locus pair alleles concerned, it cope any degree dominance random fluctuation selection intensity. However, there are restrictions using formula, most serious process must be time homogeneous. other words, coefficients homoand heterozygotes have remain constant time. When we consider fate new (including chromosome mutant) natural populations, numerous situations nonhomogeneity has taken into account because changing environment well alteration genetic background For example, inversion. If happens good combination genes at beginning, will spread reaching or leading inversion polymorphism. fitness inverted segment such best expressed exponential time, since deleterious mutants accumulate shown MUKAI ( This may apply itself neutral included does not contain genes. It possible originally advantageous gradually loses its due deterioration environment. nonhomogeneous investi-