Hansen Thomas F
University of Oslo, Department of Biology, CEES & Evogene, PB 1066 Blindern, 0316 Oslo, Norway.
J Theor Biol. 2017 Apr 21;419:36-43. doi: 10.1016/j.jtbi.2016.12.024. Epub 2016 Dec 30.
I argue that some standard accounts of fitness in finite populations are both inaccurate and conceptually misleading. I show that the usual population-genetics conceptualization of fitness as the ratio between amounts of a type after selection and before selection works just as well in finite as in infinite populations. Fitness then becomes a random variable, and selection can be conceptualized as any difference in the distribution of this variable while genetic drift can be conceptualized through realized variation in the variable. I derive exact equations for and novel approximations to the mean and variance of relative fitness, approximations for selection gradients in finite populations, and an expression for the variance effective population size in the presence of selection.
我认为，一些关于有限种群适合度的标准解释既不准确，在概念上也具有误导性。我表明，通常将适合度在种群遗传学中概念化为选择后与选择前某一类型数量之比，在有限种群和无限种群中同样适用。适合度于是成为一个随机变量，选择可以被概念化为该变量分布的任何差异，而遗传漂变可以通过该变量的实际变化来概念化。我推导出了相对适合度均值和方差的精确方程以及新的近似值、有限种群中选择梯度的近似值，还有存在选择时方差有效种群大小的表达式。
