Ref ID : 1791
Robert D. Holt; Prey communities in patchy environments. OIKOS 50:276-290, 1987
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Individuals should exploit a spatially variable environment so as to increase their Darwinian fitness. Predators should in aggregate in patches with relatively high densities of high-quality prey, and prey should in turn seek refuges providing protection from predator. This paper explores some of the consequences of such behavior for the coexistence of prey species in a patchy environment. It is argued that an aggregative predator response can lead to indirect interactions among otherwise non-interacting prey species co-occuring in a patch. In many circumstances, the interactions should be (-, -) (apparent competition), although in some situations other interactions may occur. If refuges are in short supply, then prey may compete for occupancy of refuges. Several models of such competition are presented. If predator act as density-independent mortality agents on prey outside refuges, it is shown for a simple model that two prey species cannot coexist when competing for a single refuge. Coexistence may be permitted if: (1) each prey has an exclusive refuge, (2) the dominant prey species experiences strong intraspecific interference, (3) they are trade-offs in comparative ability for refuges and for food resources, (4) the predator has a numerical response, and the prey that is subordinate in competition for refuge can better withstand predation (i.e., is superior in apparent competition). These models highlight the potential importance of spatial heterogenety for understanding prey community structure.