Avise J C, Neigel J E, Arnold J
J Mol Evol. 1984;20(2):99-105. doi: 10.1007/BF02257369.
Probability models of branching processes and computer simulations of these models are used to examine stochastic survivorship of female lineages under a variety of demographic scenarios. A parameter II, defined as the probability of survival of two or more independent lineages over G generations, is monitored as a function of founding size of a population, population size at carrying capacity, and the frequency distributions of surviving progeny. Stochastic lineage extinction can be very rapid under certain biologically plausible demographic conditions. For stable-sized populations initiated by n females and/or regulated about carrying capacity k = n, it is highly probable that within about 4n generations all descendants will trace their ancestries to a single founder female. For a given mean family size, increased variance decreases lineage survivorship. In expanding populations, however, lineage extinction is dramatically slowed, and the final k value is a far more important determinant of II than is the size of the population at founding. The results are discussed in the context of recent empirical observations of low mitochondrial DNA (mtDNA) sequence heterogeneity in humans and expected distributions of asexually transmitted traits among sexually reproducing species.
分支过程的概率模型以及这些模型的计算机模拟被用于研究在各种人口统计学情景下女性谱系的随机生存情况。一个参数II，被定义为两个或更多独立谱系在G代中的生存概率，作为种群的初始规模、承载能力下的种群规模以及存活后代的频率分布的函数进行监测。在某些生物学上合理的人口统计学条件下，随机谱系灭绝可能非常迅速。对于由n个雌性个体起始的稳定规模种群和/或围绕承载能力k = n进行调节的种群，极有可能在大约4n代内，所有后代的祖先都可追溯到单个创始雌性个体。对于给定的平均家庭规模，方差增加会降低谱系的生存概率。然而，在不断扩张的种群中，谱系灭绝显著减缓，并且最终的k值比种群初始规模对II的影响更为重要。本文将结合近期关于人类线粒体DNA（mtDNA）序列低异质性的实证观察结果以及有性生殖物种中性传播性状的预期分布来讨论这些结果。
