The distributions of the nematode parasites Heligmosomoides polygyrus and Syphacia stroma were quantified in three equal-length sections along the intestine of wood mice (Apodemus sylvaticus) trapped in three different locations in the south of England. The distribution of H. polygyrus did not change in the presence of S. stroma, this species being largely confined to the anterior third of the intestine, whether S. stroma was or was not present. However, while in single infections with S. stroma, worms were equally distributed in the anterior and middle sections of the intestine, in the presence of H. polygyrus, a higher percentage of worms was located in the middle section. This was a dose-dependent response by S. stroma to increasing worm burdens with H. polygyrus, and even relatively low intensities of infection with H. polygyrus (e.g. ≤10 worms) were sufficient to cause a posterior redistribution of S. stroma into the middle section. A similar posterior shift in the percentage distribution of S. stroma in the intestine was evident in juvenile and mature mice of both sexes, and in mice from all three study sites. The ecological significance of these results is discussed.

Recent work in regional science, geography, and urban economics has advanced spatial modeling of land markets and land use by incorporating greater spatial complexity, including multiple sources of spatial heterogeneity, multiple spatial scales, and spatial dynamics. Doing so has required a move away from relying solely on analytical models to partial or full reliance on computational methods that can account for these added features of spatial complexity. In the first part of the paper, we review economic models of urban land development that have incorporated greater spatial complexity, focusing on spatial simulation models with spatial endogenous feedbacks and multiple sources of spatial heterogeneity. The second part of the paper presents a spatial simulation model of exurban land development using an auction model to represent household bidding that extends the traditional Capozza and Helsley (1990) model of urban growth to account for spatial dynamics in the form of local land use spillovers and spatially heterogeneous land characteristics.