Figure 17.21 Community effects of a mutualism. The community effects of the mutualism were discovered when researchers fenced off areas of acacia trees from large mammalian herbivores. Fenced trees that were tended by either C. sjostedti or C. mimosa began to produce (a) fewer swollen thorns and (b) fewer nectaries. (c) In response to the changes in the trees, C. sjostedti began occupying many more acacia trees while C. mimosa occupied fewer trees. Error bars are standard errors.

Data from T. M. Palmer et al., Breakdown of an ant-plant mutualism follows the loss of large herbivores from an African savanna, Science 319 (2008): 192–195.