Katsky Venter

In 1999 Holt et al. proposed that higher trophic-level species in specialized trophic food webs should exhibit a stronger relationship to area than lower trophic level species. This hypothesis is based on the conclusion that higher trophic level species are dependant not only on their own spatial dynamics, but also those of their prey. This is because successful colonization of an area requires the ability to disperse to the area, plus the presence of a food source having already colonized the area. Consequentially the effect of area may become amplified as one moves up the food web (ie with increases in trophic rank). This compounding of constraints due to area directly on a predator dynamics, and indirectly through their prey, should produce a stronger relationship between higher trophic level species and area.

These patches were created by Diane Srivastava and Andy Gonzales in 2000 by fragmenting a contiguous moss carpet which overlay a rocky outcrop. By cutting away and removing the moss cover they created circular patches of moss that were surrounded by bare rock (a dispersal barrier to the mites and springtails). Two years later, after the community had re-equilibrated, the moss patches were collected and microarthropod community was censused. remaining moss ‘islands’ dispersal then cutting out circles of moss of various sizes and isolating them by removing the surrounding moss carpet leaving only the circlular patches (and their microarthropod commMites and other Microarthropodsunity) behind. connecting them, essentially creating moss ‘islands’, separated by an ‘sea’ of exposed rock, a barrier to immigration and emigration for the organisms understudy.

A predatory mite eating a springtail (or collembola)