<p>Datasets analyzed in the present study.</p>

Consistent with both MEH and GEH, we observe a significant decrease in both mean expression and expression slope from <i>oriC</i> to <i>ter</i> in six and four of the eight datasets, respectively. In regression models predicting gene position, the relative contributions of the two hypotheses differ across species. However, even when combined, the two hypotheses explain only a small fraction of chromosomal gene positioning, in part because the replication-dose effect is incompletely offset by compensatory evolution of individual promoter strengths.

The positional gradients in mean and growth-dependent expression are disproportionately contributed by genes involved in translation and transcription. We conclude that patterns of bacterial chromosomal gene positioning are consistent with moderate effects of selection on both mean and growth-dependent expression.</p></div>