Diversity begets diversity: Relative roles of structural and resource heterogeneity in determining rodent community structure

Environmental heterogeneity is an important determinant of the diversity of natural communities. Effects of heterogeneity can emanate from complementary effects of resource heterogeneity (variation in the number of resources) and structural heterogeneity (variation in the physical structure of the environment). We examined relative effects of structural and resource heterogeneity on the diversity of 31 desert rodent communities in the Mojave Desert. Both structural and resource heterogeneity significantly accounted for rodent species diversity. Nonetheless, when unique and shared effects were examined, only resource heterogeneity exhibited a significant unique effect, accounting for more variation than structural heterogeneity in diversity of rodent communities. When compared with results of previous studies the possibility emerges that effects of either structural or resource heterogeneity might be context dependent and determined by the taxon of focus and relative variation of these two forms of heterogeneity. Accordingly, future studies should distinguish between these two important forms of environmental heterogeneity to improve understanding of their relative impacts on diversity.