Masel Joanna
Department of Biological Sciences, Stanford University, Stanford, California 94305, USA.
Genetics. 2005 Jul;170(3):1359-71. doi: 10.1534/genetics.105.040493. Epub 2005 May 23.
Evolutionary capacitors phenotypically reveal a stock of cryptic genetic variation in a reversible fashion. The sudden and reversible revelation of a range of variation is fundamentally different from the gradual introduction of variation by mutation. Here I study the invasion dynamics of modifiers of revelation. A modifier with the optimal rate of revelation mopt has a higher probability of invading any other population than of being counterinvaded. mopt varies with the population size N and the rate theta at which environmental change makes revelation adaptive. For small populations less than a minimum cutoff Nmin, all revelation is selected against. Nmin is typically quite small and increases only weakly, with theta-1/2. For large populations with N>1/theta, mopt is approximately 1/N. Selection for the optimum is highly effective and increases in effectiveness with larger N>>1/theta. For intermediate values of N, mopt is typically a little less than theta and is only weakly favored over less frequent revelation. The model is analogous to a two-locus model for the evolution of a mutator allele. It is a fully stochastic model and so is able to show that selection for revelation can be strong enough to overcome random drift.
进化电容器以可逆的方式在表型上揭示了大量隐藏的遗传变异。一系列变异的突然且可逆的揭示与通过突变逐渐引入变异有着根本的不同。在此，我研究揭示修饰因子的入侵动态。具有最优揭示率mopt的修饰因子入侵任何其他种群的概率高于被反入侵的概率。mopt随种群大小N以及环境变化使揭示变得适应的速率theta而变化。对于小于最小临界值Nmin的小种群，所有的揭示都被选择淘汰。Nmin通常相当小，并且仅随theta的 -1/2微弱增加。对于N > 1/theta的大种群，mopt约为1/N。对最优值的选择非常有效，并且随着N >> 1/theta有效性增加。对于N的中间值，mopt通常略小于theta，并且相较于不太频繁的揭示仅受到微弱的青睐。该模型类似于一个关于突变等位基因进化的双位点模型。它是一个完全随机的模型，因此能够表明对揭示的选择可以强大到足以克服随机漂变。
