The Importance Of Relative Fitness

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chosen genotype survives; but this must be the same as the probability that a randomly chosen individual survives, regardless of information on genotype. Relative fitness. The relative fitness of a genotype (w) equals to its absolute fitness when get normalized. In the most common normalization, the absolute fitness of each genotype is divided by the absolute fitness of the fittest genotype (Barton and Turelli, 1989), such that the fittest genotype has a relative fitness of one. We can also define a selection coefficient (s), a measure of how much ‘worse’ the A2 allele is than A1. Mathematically, w2 = 1 – s. Although the definition of relative fitness is simple, the mathematical relationship between absolute and relative fitness is subtle (Bazykin, 1969; Betzig, 1986 and Beatty, 2008). In particular, there is a curve of diminishing returns between these two quantities i.e., increasing the absolute fitness of a genotype by some amount has less effect on relative fitness (compared with the mean relative fitness) than does decreasing the relative fitness of the genotype by the same amount. The importance of mathematical implication of fitness is straightforward i.e., when zygotes attempt to mature, selection acts, killing some. Because a proportion (W1) of A1 individuals and a proportion (W2) of A2 individuals survive, the proportion of individuals that carry A1 after selection acts is pW1 / (pW1 + qW2) It follows that selection will increase the frequency of the fit A1

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