Data from: Predators regulate prey species sorting and spatial distribution in microbial landscapes

1. The role of predation in determining the metacommunity assembly model
of prey communities is understudied relative to that of interspecific
competition among prey. Previous work on metacommunity dynamics of
competing species has shown that sorting by habitat patch type and spatial
patterning can be affected by disturbances. 2. Microcosms offer a useful
model system to test the effect of multi-trophic interactions and
disturbance on metacommunity dynamics. Here, we investigated the potential
role of predators in enhancing or disrupting sorting and spatial pattern
among prey in experimental landscapes. 3. We exposed multi-trophic protist
microcosm landscapes with one predator, two competing prey, two patch
resource types, and localized dispersal to three disturbance regimes
(none, low, and high). Then, we used variation partitioning and spatial
clustering analysis to analyze the results. 4. In contrast with previous
experiments that did not manipulate predators, we found that patch type
did not structure prey communities very well. Instead, we found that it
was the distribution of the predator that most strongly predicted the
composition of the prey community. 5. The predator impacted species
sorting by 1) preferentially consuming one prey, thereby acting as a
strong local environmental driver, and by 2) indirectly magnifying the
impact of patch food resources on the less preferred prey. The predator
also enhanced spatial signal in the prey community because of its limited
dispersal. Our results indicate that predators can strongly influence prey
species sorting and spatial patterning in metacommunities in ways that
would otherwise be attributed to stochastic effects, such as dispersal
limitation or demographic drift. Therefore, whenever possible, predators
should be explicitly included as separate explanatory factors in variation
partitioning analyses.