(Georgia Institute of Technology, 2009-03)
Jiang, Lin; Joshi, Hena; Patel, Shivani N.
Ecologists disagree on how diversity affects stability. At the heart of the controversy is the relationship between diversity and
population stability, with conflicting findings from both theoretical
and empirical studies. To help reconcile these results, we propose that this relationship may depend on trophic complexity, such that
positive relations tend to emerge in multitrophic but not singletrophic
communities. This hypothesis is based on the premise that stabilizing weak trophic interactions restrain population oscillations
associated with strong trophic interactions in diverse multitrophic
communities. We tested this hypothesis using simple freshwater bacterivorous
protist communities differing in diversity with and without
a predatory protist species. Coupling weak and strong trophic
interactions reduced population temporal variability of the stronginteracting
species, supporting the stabilizing role of weak interactions.
In keeping with our hypothesis, predation altered the overall
effect of diversity on population temporal stability and, in particular,
caused a reversal of the diversity-stability relationship (negative without
predators and positive with predators) for the strong-interacting
species. A similar role of predation was also observed when examining
the relationship between diversity and temporal stability of
community biomass. Together, these findings demonstrated strong
interactive effects of trophic interactions and diversity on temporal
stability of population and community properties.