What is the range of adaptive evolutionary responses to environmental change? Is there a single common, predictable solution that will always occur or a myriad of different and therefore unpredictable ways of adapting? The investigators will use the techniques of experimental evolution to examine the evolutionary responses of one hundred populations of the bacterium Escherichia coli to high temperature. Temperature is a crucial environmental variable because it controls the rates of all biological reactions that underlie such activities as carbon dioxide production, growth, and reproduction. All populations will start as identical clones, but mutations during extended serial culture will produce genetic changes which may be favored or eliminated by natural selection. After 2000 generations, the diversity of responses will be analyzed, first for differences in their relative fitness and their thermal tolerance range, then for changes in gene composition and expression. The differences among the lines will be analyzed to determine if there are preferred pathways of adaptation and whether these involve regulatory genes, whether evolution is more replicated at the level of functional category than individual gene, and whether fitness increment is proportional to the extent of change in gene expression. This experiment will create an unprecedented biological resource of both the bacterial lineages and their expression and sequence data, which will be made freely available to the scientific community for further analyses. The investigators will also use this experimental system and this project in an outreach workshop education program for local high school teachers. This workshop will provide instruction in basic concepts in evolution and examples of microevolution that are immediately accessible and easily comprehensible and present evolution as a predictive and hypothesis-testing experimental science, so that it can be explained in the high school classroom in a less controversial way.
