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Cell Size Data Through Generation 10,000

The table below provides the cell-size data used by Lenski and Travisano (1994). Measurements were obtained for the ancestor and at generations 500, 1000, 2000, 5000, 8000, 9000, 9500, and 10000 for each of the 12 evolving populations. In that paper, Fig. 1 shows the cell-size trajectory for population Ara-1 using the actual data; Fig. 2 shows trajectories for all 12 populations using curves fit to a hyperbolic model; and Fig. 3 shows the trajectory for the diversification of the 12 populations from one another based on the among-population standard-deviation in cell volume.

Average cell volumes were measured in fL (= 10-15 L) using a Coulter counter, which measures the volume displaced by each of several thousand cells as they pass through a small aperture. Cell cultures were grown to stationary-phase density for 24 h in the same DM25 liquid medium used in the long-term evolution experiment. Averages were calculated after removing particles < 0.25 fL, except for the ancestor (gen. 0) where particles < 0.15 fL were removed. These criteria gave clear separation between bacterial cells and background debris.

Each datum is the mean of two assays, except for the ancestor (gen. 0) whose value is the mean of four assays (two each for the Ara- and Ara+ states). All data were obtained as part of a single experiment, so uncontrolled temporal heterogeneity in assay conditions is not a factor. The mixed samples were used in this experiment.

The final column, labeled SD-AP, is the estimate of the among-population standard-deviation in cell volume based on analysis of variance components.

Gen.
A-1
A-2
A-3
A-4
A-5
A-6
0 0.3725 0.3725 0.3725 0.3725 0.3725 0.3725
500 0.485 0.510 0.450 0.515 0.530 0.455
1000 0.515 0.625 0.625 0.580 0.630 0.515
2000 0.600 0.660 0.630 0.700 0.705 0.545
5000 0.665 0.945 0.700 0.765 0.915 0.655
8000 0.670 0.940 0.695 0.815 0.870 0.675
9000 0.685 0.975 0.685 0.810 0.880 0.660
9500 0.670 0.935 0.685 0.735 0.850 0.685
10000 0.670 0.845 0.700 0.760 0.775 0.655

Gen.

A+1

A+2

A+3

A+4

A+5

A+6
0 0.3725 0.3725 0.3725 0.3725 0.3725 0.3725
500 0.480 0.470 0.470 0.485 0.525 0.460
1000 0.495 0.555 0.575 0.495 0.585 0.585
2000 0.580 0.675 0.645 0.675 0.675 0.640
5000 0.595 0.890 0.850 0.650 0.725 0.735
8000 0.695 0.895 0.975 0.750 0.835 1.080
9000 0.735 0.920 0.985 0.790 0.890 1.020
9500 0.720 0.940 0.965 0.835 0.895 0.965
10000 0.705 1.100 0.895 0.845 0.810 1.015

Gen.

SD-AP
0 0.0000
500 0.0252
1000 0.0437
2000 0.0480
5000 0.1119
8000 0.1312
9000 0.1261
9500 0.1174
10000 0.1355

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