Tradeoffs and coexistence in fluctuating environments: evidence for a key dispersal-fecundity tradeoff in five nonpollinating fig wasps

The ecological principle of competitive exclusion states that species competing for identical resources cannot coexist, but this principle is paradoxical because ecologically similar competitors are regularly observed. Coexistence is possible under some conditions if a fluctuating environment changes the competitive dominance of species. This change in competitive dominance implies the existence of tradeoffs underlying species' competitive abilities in different environments. Theory shows that fluctuating distance between resource patches can facilitate coexistence in ephemeral patch competitors given a functional tradeoff between species dispersal ability and fecundity. We find evidence supporting this tradeoff in a guild of five ecologically similar nonpollinating fig wasps, and subsequently predict local among patch species densities. We also introduce a novel `colonization index' to estimate relative dispersal ability among ephemeral patch competitors. We suggest that a dispersal ability-fecundity tradeoff and spatiotemporally fluctuating resource availability commonly cooccur to drive population dynamics and facilitate coexistence in ephemeral patch communities.