Grant V, Flake R H
Proc Natl Acad Sci U S A. 1974 May;71(5):1670-1. doi: 10.1073/pnas.71.5.1670.
The opposing requirements in an evolving population for a rapid rate of multiple gene substitution and for the maintenance of normal population size can be reconciled in a variety of ways. The ways out of the impasse suggested here invoke deviations from the usual assumption of a large continuous population with constant numbers. In a colonial population system there may be significant random fluctuations in the accidental mortality rate between different colonies; and those colonies with reduced numbers of accidental deaths could tolerate the larger number of selective deaths that go hand in hand with rapid evolution. In new daughter colonies founded by one or a few colonizing individuals from a large polymorphic ancestral population, some genes may reach complete fixation in one or a few generations, without the usual concomitant selective cost. Or, in the same setup, the favored alleles may change by chance from rare to moderately common, but not to complete fixation, during the founding of some daughter colonies; and this raises the allele frequencies above the low range, where the cost of selection is greatest, so that the cost of further selective changes is bearable.
在不断进化的种群中，对于快速的多基因替换率和维持正常种群规模这两种相互矛盾的需求，可以通过多种方式得到调和。这里提出的摆脱僵局的方法涉及偏离通常关于具有恒定数量的大型连续种群的假设。在一个殖民种群系统中，不同殖民地之间的意外死亡率可能存在显著的随机波动；而那些意外死亡数量减少的殖民地能够承受与快速进化相伴的更多选择性死亡。在由来自一个大型多态祖先种群的一个或几个殖民个体建立的新子殖民地中，一些基因可能在一代或几代内达到完全固定，而无需通常伴随的选择成本。或者，在相同的情况下，在一些子殖民地建立期间，有利等位基因可能偶然从稀有变为中等常见，但不会完全固定；这将等位基因频率提高到选择成本最大的低范围之上，从而使进一步选择性变化的成本变得可以承受。
