Slope estimates with associated Chi-Squared tests from Regression 4 (SI).

Slope indicates the log-log relationship between population density and mutational events per ml minus 1 (1 is subtracted to make interpretation simpler as a constant mutation rate is now defined by a slope of 0 rather than a slope of 1). slope_CI95 indicates that a 95% confidence interval on the slope estimate will be slope ± slope_CI95. pValue is calculated from a Chi-Squared test (DF = 1) comparing the original slope value to the Null Hypothesis that the slope of the given treatment = 1 (slope = 1 when mutation rate is constant with respect to population density); therefore, in treatments in which the slope significantly differs from 1, we have observed density associated mutation rate plasticity. FA and PC list the number of fluctuation assays and parallel cultures used in the analysis respectively. Plasticity shows if the treatment has DAMP (a significant inverse relationship between population density and mutation rate), reverse DAMP (a significant direct relationship between population density and mutation rate), or is Constant (relationship between population density and mutation rate not significantly different from the null expectation of a constant mutation rate).
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