The Natural Selection of Forks and Beans


Within every ecological community there exists a variety of several species. In stable communities each of these species tends to maintain a relatively stable population size, particularly when viewed over the long term. This condition is known as equilibrium. However, during times when environmental conditions fluctuate, a new equilibrium must be established. This lab will explore how the forces of natural selection operate to favor species with certain phenotypes while limiting the success of others. In this experiment four different prey species (pinto beans, red beans, white beans and split peas) and three different predator species (students equipped with a cup and a plastic knife, fork or spoon) will begin at equal levels. Predators will be allowed to "forage" / "hunt" for whichever prey type they can find. At the end of each "season" reproduction will occur within each predator and prey population. As the forces of natural selection act on each, students will observe how each prey species is affected by each predator species and visa versa. Students will also observe how the environment affects each of the predator and prey species.


Each predator will be allowed to forage for 3-5 min. Each prey item must be scooped up onto the "appendage" and then placed into the cup which must be kept upright at all times. "Shoveling" the prey item into the cup is not allowed.


  1. Which prey species do you predict will be captured the most? Why?

  2. Which prey species do you think will be captured the least? Why?

  3. Which predator species do you think will capture the most number of prey? Why?

  4. Which predator species do you think will capture the least number of prey? Why?

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