Smaller habitats contain fewer species. This species-area relationship (SAR) is fundamental to predicting the effects of habitat destruction on species extinction. The slope of this relationship determines how many species go extinct as more habitat is destroyed. A steep SAR suggests that small decreases in habitat area will result in extensive species extinctions. However, habitat destruction also eliminates top predators with large habitat requirements, which could decrease prey species extinction. These conflicting impacts of habitat destruction on species extinction suggest that a loss of top predators might alter SAR slopes or the rate at which prey species go extinct with increasing habitat destruction. To explore this idea, Ryberg and Chase develop a mathematical model which predicts that predators will reduce SAR slopes, indicating that the negative impact of habitat destruction on species diversity will be diminished in the presence of predators. They test this hypothesis in an ecosystem threatened by habitat destruction, Ozark glades, which are rocky prairies that contain patchily distributed populations of predatory Collared lizards and their grasshopper prey. Preliminary data on grasshopper prey diversity in glades of varying size with and without lizards reveal a shallower grasshopper SAR in the presence of lizard predators. The generality of this result will be evaluated statistically with additional spatial and temporal sampling. This research will improve current glade restoration efforts, promote public education through scientific outreach programs related to glade conservation, and increase research opportunities for undergraduate students, particularly those from underrepresented backgrounds.
