Differential Patterns of Gene Expression and Gene Complement in Laboratory-Evolved Lines of E. coli

Laboratory selection experiments play a prominent role in understandingorganismal adaptation. Although bacteria are not yet commonlyused for such experiments, they are well suited for analysesof both the organismic and the genetic basis of adaptation.Bacteria can be maintained in large populations while occupyinglimited laboratory space, have short generation times, are wellcharacterized physiologically, biochemically, and genetically,and are readily frozen and revived from the freezer. In addition,the genomes of many species are completely sequenced and knowledgeof gene function is unparalleled. Here we review general aspectsof selection experiments, the history of using selection experimentsin combination with thermal biology and genomics, and highlightfindings from six lines of Escherichia coli adapted to hightemperature (41.5°C), including changes in organismal fitness,physiological performance, gene complement and gene expression.Our results are an example of the powerful insights that canbe discovered by combining the tools and analyses of many biologicaldisciplines including genomics, evolutionary biology, genetics,and evolutionary physiology.