专题：Nature报道
突变稳健性（Mutational robustness）在演化中所起作用一直是一个存在很对争论和争议的问题。一方面，它似乎通过在发生环境变化时使得一种新的表现型不易形成来妨碍适应；另一方面，它似乎又能帮助一种生物使其表现型在可能不利的突变面前得到缓冲。一种生物怎样解决这种矛盾、从而同时具有稳健性和适应性呢？
现在，一个定量种群遗传学模型对这一问题给出了一个可能的解答。该模型表明，突变稳健性技能妨碍适应，又能帮助适应，到底如何则取决于种群大小、突变速度和适应性环境的结构。
推荐原始出处：
Nature 463, 353-355 (21 January 2010) | doi:10.1038/nature08694
Mutational robustness can facilitate adaptation
Jeremy A. Draghi1, Todd L. Parsons1, Günter P. Wagner3 " Joshua B. Plotkin1,2
1 Department of Biology,
2 Program in Applied Mathematics and Computational Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
3 Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut 06520, USA
4 Correspondence to: Joshua B. Plotkin1,2 Correspondence and requests for materials should be addressed to J.B.P.
Robustness seems to be the opposite of evolvability. If phenotypes are robust against mutation, we might expect that a population will have difficulty adapting to an environmental change, as several studies have suggested1, 2, 3, 4. However, other studies contend that robust organisms are more adaptable5, 6, 7, 8. A quantitative understanding of the relationship between robustness and evolvability will help resolve these conflicting reports and will clarify outstanding problems in molecular and experimental evolution, evolutionary developmental biology and protein engineering. Here we demonstrate, using a general population genetics model, that mutational robustness can either impede or facilitate adaptation, depending on the population size, the mutation rate and the structure of the fitness landscape. In particular, neutral diversity in a robust population can accelerate adaptation as long as the number of phenotypes accessible to an individual by mutation is smaller than the total number of phenotypes in the fitness landscape. These results provide a quantitative resolution to a significant ambiguity in evolutionary theory.
