Evolution in stationary phase: novelty

As cultures age, cells are competing against one another for access to nutrients. This competition is fierce. As you saw in ON GROWTH by day 3, over 99% of the cells in the culture will die.

Were the survivors chosen "randomly" or do that have an survival advantage over cells in 'unaged" cultures.

To determine whether the surviving cells in a starved population have an inheritable advantage over unstarved cells for survival under starvation conditions we will set up a competition experiment.

Take an aliquot from an aged (10 day old) nalR or strR cultures and mix it with an equal number of cells from a fresh 1 day old stationary culture of the other strain (mix old nalR with young strR or visa versa).

Now tract the relative frequencies of the two strains over the next two months.

• Describe in a paragraph or two the result of your experiment.
• How would the results differ if you mixed two young or two aged strains, rather than an aged and a young strain.
• Make a prediction: if you diluted equal numbers of aged and young cells into fresh LB, which do you think would dominant the population after 6 hours, that is before the culture reached stationary phase? Explain your reasoning.