Data from: Allelopathy prevents competitive exclusion and promotes phytoplankton biodiversity

It has been hypothesized that allelopathy can prevent competitive
exclusion and promote phytoplankton diversity in aquatic ecosystems, where
numerous species coexist on a limited number of resources. However,
experimental proof-of-principle is not available to support this
hypothesis. Here we present the first experimental evidence to support
this hypothesis by demonstrating that allelopathy promotes the coexistence
of two phytoplankton species, Ankistrodesmus falcatus and Oscillatoria
sp., that compete for a single limiting nutrient. By performing long-term
competition experiments in nitrate-limited continuous cultures, and by
describing the population dynamics using a mechanistic model, we
demonstrate that when allelopathy comes into play, one of the following
outcomes is possible depending on the relative initial abundances of the
species: dominance of the stronger competitor for nitrate (the
non-allelopathic species), oscillatory coexistence, or dominance of the
weaker competitor (the allelopathic species). Our model analysis revealed
that sustained oscillatory coexistence of the two species would be a
common outcome of this experiment. Our study confirms for the first time,
based on laboratory experiments combined with mechanistic models, that
allelopathy can alter the predicted outcome of inter-specific competition
in a nutrient-limited environment and increase the potential for the
coexistence of more species than resources, thereby contributing to the
identification of endogenous mechanisms that explain the extreme diversity
of phytoplankton communities.