Population structure, fitness surfaces, and linkage in the shifting balance process.
Population structure, fitness surfaces, and linkage in the shifting balance process.
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DOI：
10.1017/s0016672300034418
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发表时间：
1995-08
期刊：
影响因子：
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通讯作者：
A. Bergman;D. Goldstein;K. Holsinger;M. Feldman
中科院分区：
文献类型：
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作者：
A. Bergman;D. Goldstein;K. Holsinger;M. Feldman
赖特首先提出了随机遗传漂移和经典的质量作用选择相结合的想法，使种群能够在复杂的适应表面上找到最高峰。他的理论假设了大量但有结构的种群，在这些种群中，交配在空间上是局部的。如果基因流足够低，亚群(Deme)足够小，他们将受到遗传漂移的影响。远处的德梅斯独立漂移，允许对自适应曲面进行多次独立搜索。一个移到更高顶峰的德米人，通过移民可以使其余的德米人转移到更高的顶峰。这种转变的可能性取决于迁移率。以前的研究已经得出结论，几乎不需要迁移就能实现适应峰值的移动，这是赖特移动平衡过程(SBP)的最后阶段的特征。在这里，我们介绍了一项计算机研究的结果，该研究调查了分散距离、适应度面上位度和重组对移位平衡过程的作用。特别是，我们衡量了它们对人群平均适合度的影响。我们表明，在一定的扩散距离范围内，SBP的优势是上位量的单调递增函数。我们的结果表明，导致SBP在提高平均适合度方面效果最大的分散程度取决于上位性的程度。最后，对于低水平的上位性，较高的重组表现得更好，而对于中间水平，较低的重组导致更大的SBP优势。
Wright first introduced the idea that random genetic drift and classical mass-action selection might combine in such a way as to allow populations to find the highest peak in complicated adaptive surfaces. His theory assumes large but structured populations, in which mating is spatially local. If gene flow is sufficiently low, and the subpopulations (demes) are small enough, they will be subject to genetic drift. Distant demes drift independently, allowing many independent searches of the adaptive surface to take place. A deme that has shifted to a higher peak can, by emigration, cause the rest of the demes to shift to the higher peak. The probability of this shift depends on the migration rate. Previous studies have concluded that very little migration is necessary to effect the shift in adaptive peaks that characterizes the last phase of Wright's Shifting Balance Process (SBP). Here we present the results of a computer study that investigates the roles of dispersal distance, the degree of epistasis in the fitness surface, and recombination on the shifting balance process. In particular, we measure their effect on the population's mean fitness. We show that over a range of dispersal distances the advantage of the SBP is a monotonically increasing function of the amount of epistasis. Our results show that the extent of dispersal that results in the greatest effect of the SBP in increasing mean fitness depends on the extent of epistasis. Finally, for low levels of epistasis, higher recombination performs better, while for intermediate levels, lower recombination results in a greater advantage of the SBP.