Dispersal is a vital component of the life- history of nearly all organisms. The ability to disperse determines the distribution and abundance of a species and thus its community dynamic at different sites. The scientific challenge is to design standardized laboratory experiments that not only record the effects of single factors but also includes the multi-causal nature of dispersal. Here we tested the effect of the environmental factors density, food availability and predation and the combinations thereof on the dispersal of five free- living nematode species by performing experiments in two-patched systems. We hypothesized that emigration is generally positively correlated with the intrinsic rate of natural increase and would decrease with increasing food availability and increase both with the presence of a predator and at higher initial population densities. These predictions were tested both using single-species tests with laboratory cultures as well as using intact natural nematode communities to investigate whether environmental factors determine the composition of dispersing species.

The results of our study revealed a positive correlation between dispersal and intrinsic growth ability, whereas the studied nematode species differed in their dispersal patterns, both under control conditions and in response to bottom-up, top-down, and density dependent stimuli. Despite the species- specific differences in dispersal behavior in response to the environmental factors, the availability of food appeared as the main driver. This was especially pronounced regarding a natural nematode community. Our experiments emphasize the central role of food availability in spatial structuring nematode communities.