1, Food-web complexity-stability relations are central to ecology, and many
empirical studies show greater food-web complexity leads to lower populati
on stability. Here, predator population variability decreased with increasi
ng prey diversity in aquatic microcosm experiments, an example of greater f
ood-web complexity leading to greater population stability.
2, Prey diversity as well as different sets of prey species within each lev
el of prey diversity produced differences in predator population dynamics,
demonstrating the importance of both prey composition and prey diversity in
determining predator population stability.
3, Prey diversity can affect predator population dynamics through at least
three groups of mechanisms: prey reliability, prey biomass, and prey compos
ition mechanisms. The results suggest that greater prey reliability at high
er prey diversities enhances predator stability and provide support for Mac
Arthur (1955).