Vidan, E. - Department of Food Science, Institute of Post-Harvest and Food Science, The Volcani Center, ARO, Israel.  
Rapaport, A. - Department of Food Science, Institute of Post-Harvest and Food Science, The Volcani Center, ARO, Israel; Faculty of Agriculture, Food and Environment, Hebrew University, Israel.

Doron, J. - Department of Food Science, Institute of Post-Harvest and Food Science, The Volcani Center, ARO, Israel.

Harush, A. - Department of Food Science, Institute of Post-Harvest and Food Science, The Volcani Center, ARO, Israel

The distribution of biotic and abiotic factors creates ecological niches. Despite the link between both the biotic and abiotic components of a species niche and its geographic distribution, most approaches to species-distribution modeling correlate the occurrence of a single species with broad-scale environmental variables, but do not include biotic interactions. We studied the relative effects of biotic and abiotic factors on community composition and dynamics in a man-made ecosystem (i.e., a grain-storage system). We studied the population dynamics of 10 insect species at two climatically distinct study sites: a site with a Mediterranean climate and a site with a semi-arid climate. All species were found to aggregate at both sites and similar community dynamics were observed at the two sites. However, there were differences in the relative importance of biotic and abiotic factors in the formation of communities in the two habitats. This difference yielded different population dynamics and spatial distributions. The Mediterranean site was characterized by species niche overlap and communities at that site were less dense. In contrast, in the semi-arid habitat, species tended to have distinct spatial distribution and there was a high level of community density. These results can be viewed as examples of within- and between-patch coexistence. We discuss the possibility that there may be gradual shifts in the relative importance of within- and between-patch coexistence. Small continuous changes, such as global climate change, could induce such shifts, leading to similar temporal and spatial patterns in the current Mediterranean climate.