Center for Mechanisms of Evolution, Biodesign Institute, Arizona State University, Tempe, Arizona.
Elife. 2018 Jun 21;7:e34820. doi: 10.7554/eLife.34820.
Most cellular features have a range of states, but understanding the mechanisms responsible for interspecific divergence is a challenge for evolutionary cell biology. Models are developed for the distribution of mean phenotypes likely to evolve under the joint forces of mutation and genetic drift in the face of constant selection pressures. Mean phenotypes will deviate from optimal states to a degree depending on the effective population size, potentially leading to substantial divergence in the absence of diversifying selection. The steady-state distribution for the mean can even be bimodal, with one domain being largely driven by selection and the other by mutation pressure, leading to the illusion of phenotypic shifts being induced by movement among alternative adaptive domains. These results raise questions as to whether lineage-specific selective pressures are necessary to account for interspecific divergence, providing a possible platform for the establishment of null models for the evolution of cell-biological traits.
大多数细胞特征都具有一系列状态，但理解导致种间差异的机制是进化细胞生物学面临的挑战。针对在持续选择压力下，面对突变和遗传漂变的共同作用，可能进化的平均表型分布模型被开发出来。平均表型将偏离最佳状态，其偏离程度取决于有效种群大小，在没有多样化选择的情况下，可能会导致实质性的差异。平均的稳定状态分布甚至可能是双峰的，一个域主要受选择驱动，另一个域主要受突变压力驱动，导致表型转变的假象是由在替代适应性域之间的移动引起的。这些结果提出了这样一个问题，即是否需要特定于谱系的选择压力来解释种间差异，为细胞生物学特征进化的零模型的建立提供了一个可能的平台。
