The study of biogeography involves how geography influences species distribution and diversity. Working in an area as geographically complex as the Greater Grand Canyon Ecosystem has led to several questions regarding the influence of landform evolution on biodiversity. For example, the Grand Canyon is a 2.48 km-deep slash in the landscape that was formed during the plateau uplift about 75 mya. The canyon influences species ranges and gene flow in three possible ways: as a corridor for low elevation riverine and desert habitats through the plateau; as a partial or full barrier across the plateau; and as a refuge for species requiring rare microhabitats. There are also many wide-ranging species for which the Grand Canyon has no effect. Dr. Stevens recently contributed to and edited a book on biogeography, “Global Advances in Biogeography” (Stevens 2012) in which he explains the significance of the Grand Canyon to biodiversity.
Other current biogeography projects include an analysis of aquatic beetles in the southwest, a particular genus of Sphecidae wasps in the Grand Canyon Ecoregion, and the effects of landform age on Neuroptida species richness.