Data from: Consumer interaction strength may limit the diversifying effect of intraspecific competition: a test in alewife (Alosa pseudoharengus).

Intraspecific competition is considered a principal driver of dietary
variation, however, empirical studies provide mixed support for this
mechanism. Here we link comparative and experimental work testing the
effects of competition and resource availability on the dietary variation
of alewife (Alosa pseudoharengus). Alewife, a consumer with extreme
effects on its resources, are specifically utilized to additionally test
the idea that that the strength of the interaction between a consumer and
its resources may diminish the diversifying effect of competition. First,
we compared the short- and long-term diet measures of from wild
populations across a range of densities. Second, in a series of
large-scale field mesocosm experiments we explored the influence of
competition and interaction strength on alewife dietary variation. Results
from the whole lake comparison and field experiments indicated that
increasing competition was negatively correlated with population dietary
variation. Further, altering the strength of the interaction between
alewife and their prey via prey supplementation eliminated this negative
relationship. Collectively, our results suggest that competitive
interactions may not drive dietary diversification in highly effective
consumers. Our results also suggest that further consideration of the
strength of species interactions (and the consumer traits that underlie
them) would improve our understanding of the link between intraspecific
competition and variation