9527710 Rypstra This research focuses on the effect of tillage practices in soybean fields on the survival and coexistence of two species of wolf spider. We will test the hypothesis that the coexistence of these two spider species differing in competitive ability, colonization ability, and longevity depends on the degree of fragmentation and disturbance in their habitat. The two species of spider prefer patches of plant debris on the soil surface - a feature of soybean fields maintained under conservation tillage practices. We will monitor the spiders in tilled and untilled soybean fields and manipulate the spatial pattern of their environment by localized tilling or addition of mulch. These manipulations will enable us to understand how habitat destruction and fragmentation change the interaction between the two species and determine the situations where the interaction results in localized extinction. Empirical data will be used to build a computer model to extend our understanding of species coexistence to longer time frames and more general situations. The spider community is diverse and constitutes nearly 50% of the predatory fauna in soybean fields, but it is poorly understood. Understanding the activities and interactions of spiders in conventional till and no-till soybean fields is a critical step towards understanding the effect of tillage practices on this important crop.
