Mutations and the Distribution of Lifetime Reproductive Success

Evolution proceeds in large part by the establishment of mutations in the genome of organisms, but even an advantageous mutation may be lost by chance. The probability of such loss is the extinction probability of an individual with a random lifetime reproductive success (LRS). We show here that the traditional approximation of extinction probability in terms of the mean and variance of LRS does not always apply, because the LRS has a skewed, often multimodal, distribution. To exemplify distinct life history patters, we use the Hadza and Pacific Chinook salmon. The traditional approximation overestimates the exact extinction probability from complete LRS distribution. An accurate analysis of the distribution of LRS strengthens our ability to successfully analyze evolution.