Evolutionary rescue is the process whereby a declining population may start growing again, thus avoiding extinction, via an increase in the frequency of fitter genotypes. These genotypes may either already be present in the population in small numbers, or arise by mutation as the population declines. We present a simple two-type discrete-time branching process model and use it to obtain results such as the probability of rescue, the shape of the population growth curve of a rescued population, and the time until the first rescuing mutation occurs. Comparisons are made to existing results in the literature in cases where both the mutation rate and the selective advantage of the beneficial mutations are small.

进化拯救是一个减少的种群可能再次开始增长的过程，从而通过增加更适合基因型的频率来避免灭绝。这些基因型可能已经少量存在于种群中，或者随着种群的减少而通过突变产生。我们提出了一个简单的二类离散时间分支过程模型，并用它来获得拯救概率、拯救种群的种群增长曲线的形状以及第一次拯救突变发生的时间等结果。在突变率和有益突变的选择优势都很小的情况下，与文献中的现有结果进行了比较。