The following questions refer to Figure 27.1 below, which is the same as Figure 27.10 in the textbook.
In this 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.

Figure 27.1
-Which term best describes what has occurred among the experimental populations of cells over this 8-year period?
A)microevolution
B)speciation
C)adaptive radiation
D)sexual selection
E)stabilizing selection

Question

The following questions refer to Figure 27.1 below, which is the same as Figure 27.10 in the textbook.
In this 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.
  
Figure 27.1
-Which term best describes what has occurred among the experimental populations of cells over this 8-year period?
A)microevolution 
B)speciation 
C)adaptive radiation 
D)sexual selection 
E)stabilizing selection

Quizplus · Accepted Answer

This experiment shows evidence of microevolution, as the populations of E. coli have evolved over time in response to the low-glucose conditions. The fitness tests demonstrate changes in the populations' adaptations to the environment. However, there is no evidence of speciation or adaptive radiation occurring in this experiment. Sexual selection and stabilizing selection are also not relevant to this specific experiment.

The Following Questions Refer to Figure 27