Abstract
Evolution is an on-going process. Therefore, it can be studied experimentally in organisms with rapid generations. We have maintained 12 populations of Escherichia coli in a simple environment for more than 25 years and 60,000 generations. Two aims of this experiment are to characterize the trajectory of evolution and examine the repeatability of phenotypic and genomic changes. We have quantified the dynamics of adaptation by natural selection, documented many cases of parallel evolution, observed changes in the underlying mutation rate, and seen the appearance of a novel physiological function that transcends the usual definition of E. coli as a species. We have sequenced hundreds of complete genomes to find the mutations in time-series of samples from the populations. These genomic data provide insights into the dynamic coupling of phenotypic and genotypic evolution during periods of optimization and innovation.
Richard Lenski
Michigan State University
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