Figure 11.17 The ideal free distribution in stickleback fish. When six fish were placed in an aquarium with the two ends receiving a five-to-one difference in food rations, the fish distributed themselves in a four-to-one ratio. As a result, each fish received a similar per capita amount of food. Error bars are standard deviations.

Data from M. Milinski, An evolutionarily stable feeding strategy in sticklebacks, Zeitschrift für Tierpsychologie 51 (1979): 36–40.