Finkel S E, Kolter R
Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.
Proc Natl Acad Sci U S A. 1999 Mar 30;96(7):4023-7. doi: 10.1073/pnas.96.7.4023.
Models of evolutionary processes postulate that new alleles appear in populations through random spontaneous mutation. Alleles that confer a competitive advantage in particular environments are selected and populations can be taken over by individuals expressing these advantageous mutations. We have studied the evolutionary process by using Escherichia coli cultures incubated for prolonged periods of time in stationary phase. The populations of surviving cells were shown to be highly dynamic, even after many months of incubation. Evolution proceeded along different paths even when the initial conditions were identical. As cultures aged, the takeovers by fitter mutants were incomplete, resulting in the coexistence of multiple mutant forms and increased microbial diversity. Thus, the study of bacterial populations in stationary phase provides a model system for understanding the evolution of diversity in natural populations.
进化过程模型假定新的等位基因通过随机自发突变出现在种群中。在特定环境中具有竞争优势的等位基因会被选择，种群可能会被表达这些有利突变的个体所占据。我们通过在稳定期长时间培养大肠杆菌来研究进化过程。即使经过数月培养，存活细胞的种群仍显示出高度动态性。即使初始条件相同，进化也会沿着不同路径进行。随着培养物老化，更适应环境的突变体的接管并不完全，导致多种突变形式共存，微生物多样性增加。因此，对稳定期细菌种群的研究为理解自然种群中多样性的进化提供了一个模型系统。
