Fig. 3.

New Tn916 insertions emerged frequently in response to TGC selection. Every new Tn916 insertion site that appeared during adaptation in both populations above 1% frequency was mapped to the closed E. faecalis V583 genome. Twenty-eight new insertion sites were identified from experimental Run 1 (green) and 22 (red) from experimental Run 2. Several insertion sites occurred in regions of S613 absent from V583, including three sites during Run 1 and two during Run 2 (supplementary table S3, Supplementary Material online). Blue shows the original position of Tn916, which remained at 100% during both adaptation experiments. Only five insertion sites occurred in identical locations between the two experimental runs for a total of 44 unique sites. The identification of many unique insertion sites is consistent with a model where the conjugal-transfer of Tn916 facilitated the rapid spread of TGC resistance among the adapting populations.