Average change in cell size from the ancestral state after 10,000 generations

Range ≈0.44 µm^3
Organism Bacteria Escherichia coli
Reference Lenski RE, Travisano M. Dynamics of adaptation and diversification: a 10,000-generation experiment with bacterial populations. Proc Natl Acad Sci U S A. 1994 Jul 19 91(15):6808-14. p.6810 left column bottom paragraphPubMed ID8041701
Method "Twelve populations of E. coli B were propagated in replicate environments for 1500 days (10,000 generations). Each population was founded by a single cell from an asexual clone, and so there was initially no genetic variation either within or between replicate populations (except for a neutral marker used to identify populations). The experimental environment consisted of a serial transfer regime, in which populations were diluted (1:100) each day into 10 ml of a glucose-limited minimal salts medium that supports ˜5 x 10^7 cells per ml. Populations were maintained at 37°C with aeration. Every day, the bacteria underwent a lag phase prior to growth, followed by a period of sustained growth, eventual depletion of the limiting glucose, and starvation until the next serial transfer. The 1:100 dilution permits ˜6.6 (log2[100]) cell generations per day. Samples from each population were periodically stored at -80°C, along with the common ancestor...Cell sizes were obtained by using an electronic device that measures the volume displaced by a particle (refs 3, 4)."
Comments "After 10,000 generations, the among-population standard deviation was ˜0.14 fl, as compared with the average change in cell size from the ancestral state of ˜0.44 fl."
Entered by Uri M
ID 110462