Abstract
Thermally evolved lines of Escherichia coli propagated by Bennett and Lenski have been used to investigate a number of hypotheses concerning evolutionary and phenotypic responses to environmental changes responses. Tests of the `beneficial acclimation' and `jack of all environments/master of none' hypotheses using temperature as an environmental variable have yielded surprisingly counter-intuitive results. Currently, we are propagating new evolutionary lines of E. coli in environments ranging in pH from acidic (pH 5.3) to alkaline (pH 7.9), with some lines alternating between these extremes or experiencing randomly varying pH. These lines will be used to investigate whether the evolutionary and acclimatory patterns seen in thermally evolved lines are sufficiently generalized to recur in different abiotic environments. In addition, we are investigating the possibility of generalized stress adaptation by examining the performance of lines adapted to one type of environmental stress (such as temperature) when exposed to a novel environmental stress (such as pH). Supported by NSF postdoctoral fellowship DBI-9804162 to AJC and NSF/IBN-9507416 to AFB and REL.