Question

In lenski's e coli experiment, what evidence suggests that the ability to effectively exploit citrate was a complex adaptation that involved more than a single mutation

Answer 1

The E. coli long-term evolution experiment(LTEE) is an ongoing study in experimental evolution led by Richard Lenski that has been tracking genetic changes in 12 initially identical populations of asexual Escherichia coli bacteria since 24 February 1988.[2] The populations reached the milestone of 50,000 generations in February 2010 and 66,000 in November 2016.[3] Lenski performed the 10,000th transfer of the experiment on March 13, 2017.[4]

Over the course of the experiment, Lenski and his colleagues have reported a wide array of phenotypic and genotypic changes in the evolving populations. These have included changes that have occurred in all 12 populations and others that have only appeared in one or a few populations. For example, all 12 populations showed a similar pattern of rapid improvement in fitness that decelerated over time, faster growth rates, and increased cell size. Half of the populations have evolved defects in DNA repair that have caused mutator phenotypes marked by elevated mutation rates. The most striking adaptation reported so far is the evolution of aerobic growth on citrate, which is unusual in E. coli, in one population at some point between generations 31,000 and 31,500.[5][6]

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