In an 8-year experiment, 12 populations of e. coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. each culture was introduced to fresh growth medium every 24 hours. occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor) e. coli population. e. coli cells typically make most of their atp by metabolizing glucose. under the conditions of this experiment, what should be true of e. coli's generation time (especially early in the course of the experiment, but less so later on)?