title: Consumer interaction strength may limit the diversifying effect of intraspecific competition: a test in alewife (Alosa pseudoharengus).
abstract: Intraspecific competition is considered a principal driver of dietary variation, but 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 the alewife (Alosa pseudoharengus). The alewife, a consumer with extreme effects on its resources, was specifically utilized to additionally test the idea that strong interactions between a consumer and its resources can diminish the diversifying effect of competition. First, we compared the short- and long-term diet measures of wild populations across a wide range of densities. Second, in a pair of large-scale field mesocosm experiments, we explored the influence of competition and interaction strength on alewife dietary variation. Results from a 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 the alewife and its prey via prey supplementation eliminated this negative relationship. Collectively, our results suggest that competitive interactions may not drive dietary diversification in the alewife and, potentially, in other highly effective consumers. Our results also indicate 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.
authors.affiliation: Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511, USA. andrew.jones@yale.edu
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Jones
authors.forename: David M
authors.initials: DM
authors.lastname: Post
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D044822:Biodiversity; D003163:Competitive Behavior; D004032:Diet; D005247:Feeding Behavior; D005399:Fishes; D060106:Lakes; D008954:Models, Biological; D015233:Models, Statistical; D011156:Population Density