Thursday, August 7, 2008 - 8:00 AM

COS 83-1: Communities on the move: Insect populations crossing the cultivated/wildlands interface in the western Great Basin

Matthew Forister, University of Nevada, Reno


An increasing portion of the Earth’s surface is converted to anthropogenic habitats every year. As these transformed areas replace natural habitats, organisms may respond in a number of ways: they may be locally extirpated, they may persist in the interstices with reduced population sizes, or they may utilize the novel habitats and resources associated with human development. While extirpations and reductions in density have been widely documented, we know relatively little about the latter possibility, even though this option (persistence in anthropogenic habitats) may represent the primary fate for the majority of species that are going to survive in the 21st century and beyond. Cultivated alfalfa (Medicago sativa) is one of the most widespread crops in western North America, and (particularly in the Great Basin) alfalfa fields often abut directly against remaining native habitat. Insect communities across the alfalfa/wildlands interface were sampled at three locations in western Nevada to answer the following questions: (1) how many native species of insects colonize alfalfa fields? and (2) to what extent do insect communities overlap across the adjoining cultivated and native, sage brush habitats?   


A large number of native insect species (greater than 100 morphospecies) were found inhabiting alfalfa fields throughout the growing season. Species richness in the two habitats (native and cultivated) was similar, though the communities in the alfalfa fields were more homogenous across space and time. Finally, overlap (in terms of species found in both habitats) varied by trophic level and life history. These results suggest that the novel habitat is being heavily used by native insect species in the Great Basin, though the demographic, ecological, and evolutionary impacts of this habitat use remain to be investigated.