Bard Jonathan B L
Department of Anatomy, Physiology & Genetics, University of Oxford, Oxford OX313QX, UK.
Biology (Basel). 2018 Feb 26;7(1):20. doi: 10.3390/biology7010020.
Evolutionary change comes from natural and other forms of selection acting on existing anatomical and physiological variants. While much is known about selection, little is known about the details of how genetic mutation leads to the range of heritable anatomical variants that are present within any population. This paper takes a systems-based view to explore how genomic mutation in vertebrate genomes works its way upwards, though changes to proteins, protein networks, and cell phenotypes to produce variants in anatomical detail. The evidence used in this approach mainly derives from analysing anatomical change in adult vertebrates and the protein networks that drive tissue formation in embryos. The former indicate which processes drive variation-these are mainly patterning, timing, and growth-and the latter their molecular basis. The paper then examines the effects of mutation and genetic drift on these processes, the nature of the resulting heritable phenotypic variation within a population, and the experimental evidence on the speed with which new variants can appear under selection. The discussion considers whether this speed is adequate to explain the observed rate of evolutionary change or whether other non-canonical, adaptive mechanisms of heritable mutation are needed. The evidence to hand suggests that they are not, for vertebrate evolution at least.
进化变化源于自然选择和其他形式的选择作用于现有的解剖学和生理学变异。虽然我们对选择了解很多，但对于基因突变如何导致任何种群中存在的可遗传解剖学变异范围的细节却知之甚少。本文采用基于系统的观点来探索脊椎动物基因组中的基因突变如何通过蛋白质、蛋白质网络和细胞表型的变化向上起作用，从而产生解剖学细节上的变异。这种方法所使用的证据主要来自对成年脊椎动物解剖学变化以及驱动胚胎组织形成的蛋白质网络的分析。前者表明哪些过程驱动变异——这些主要是模式形成、时间安排和生长——后者表明其分子基础。然后本文研究了突变和遗传漂变对这些过程的影响、种群中由此产生的可遗传表型变异的性质，以及在选择作用下新变异出现速度的实验证据。讨论部分考虑这种速度是否足以解释观察到的进化变化速率，或者是否需要其他非经典的、可遗传突变的适应性机制。现有证据表明，至少对于脊椎动物进化来说并非如此。
