Data from: Herbivory can increase plant fitness via reduced interspecific competition – evidence from models and mesocosms

Herbivores are generally considered to reduce plant fitness. However, as
in natural communities herbivores often feed on several competing plant
species, herbivores can also increase plant fitness by reducing
interspecific competition among plants. In this study, we developed a
testable model to predict plant fitness in the presence of an
interspecific competitor and an herbivore that feeds on both plant
species. Our model allows us to predict at which herbivore and competitor
densities the focal species will benefit from herbivory. This can be
estimated by quantifying the effects of the herbivore on the fitness of
the focal plant and on its competitor, and by estimating the levels of
intra- and interspecific competition in a pair-wise fashion, respectively.
We subsequently validated the model in indoor microcosms using three
interacting species: an aquatic macrophyte (the giant
duckweed Spirodela polyrhiza), its native competitors (green
algae), and its native herbivore (the pond snail Lymnaea stagnalis).
Additional outdoor mesocosm experiments supported our model under natural
conditions. Together, this study provides a conceptual framework to
understand how herbivores shape plant fitness in a community context.