You only go extinct once....

Assume that you have a new mutation, totally novel. What's its probability of going extinct in one generation? That is, it doesn't get passed on....Consider, you have a population of N individuals. Fix the population size across nonoverlapping generations. So, in generation t you have N individuals and in t + 1 you have N individuals. In the first generation of the mutation the proportion in the population is 1/N, that is, there is one mutant amongst N individuals (ergo, N - 1 other copies). The probability that the mutant is never "drawn" (copied) to the next generation in this fixed population is (1 - 1/N)N 1 - 1/N represents the non-mutants, and there are N draws since the population across generations is fixed. For example, if there are 100 individuals (haploid) and 99 are non-mutants, and the next generation will also have 100 individuals, there are 100 opportunities for ...