Department of Computer Science, The University of Chicago, Chicago, Illinois 60637, USA.
Nature. 2011 May 18;474(7352):502-5. doi: 10.1038/nature09992.
The boundaries between prokaryotes, unicellular eukaryotes and multicellular eukaryotes are accompanied by orders-of-magnitude reductions in effective population size, with concurrent amplifications of the effects of random genetic drift and mutation. The resultant decline in the efficiency of selection seems to be sufficient to influence a wide range of attributes at the genomic level in a non-adaptive manner. A key remaining question concerns the extent to which variation in the power of random genetic drift is capable of influencing phylogenetic diversity at the subcellular and cellular levels. Should this be the case, population size would have to be considered as a potential determinant of the mechanistic pathways underlying long-term phenotypic evolution. Here we demonstrate a phylogenetically broad inverse relation between the power of drift and the structural integrity of protein subunits. This leads to the hypothesis that the accumulation of mildly deleterious mutations in populations of small size induces secondary selection for protein-protein interactions that stabilize key gene functions. By this means, the complex protein architectures and interactions essential to the genesis of phenotypic diversity may initially emerge by non-adaptive mechanisms.
原核生物、单细胞真核生物和多细胞真核生物之间的界限伴随着有效种群大小的数量级降低，同时随机遗传漂变和突变的影响也会放大。选择效率的这种下降似乎足以在非适应性的方式上影响基因组水平上的广泛属性。一个关键的遗留问题是，随机遗传漂变的力量变化在多大程度上能够影响亚细胞和细胞水平的系统发育多样性。如果是这样的话，种群大小将不得不被视为长期表型进化潜在机制途径的一个潜在决定因素。在这里，我们展示了漂移能力与蛋白质亚基结构完整性之间广泛存在的逆向关系。这就提出了这样一种假设，即在小种群中积累轻度有害突变会诱导对稳定关键基因功能的蛋白质-蛋白质相互作用的二次选择。通过这种方式，对表型多样性的产生至关重要的复杂蛋白质结构和相互作用可能最初通过非适应性机制出现。
