title: Large effects of consumer offense on ecosystem structure and function.
abstract: Study of the role of within-species adaptation in ecological dynamics has focused largely on prey adaptations that reduce consumption risk (prey defense). Few, if any, studies have examined how consumer adaptations to overcome prey defenses (consumer offense) affect ecosystem structure and function. We manipulated two sets of genotypes of a planktonic herbivore (Daphnia pulicaria) in a highly productive ecosystem with abundant toxic prey (cyanobacteria). The two sets of consumer genotypes varied widely in their tolerance of toxic cyanobacteria in the diet (i.e., sensitive vs. tolerant). We found a large effect of tolerant D. pulicaria on phytoplankton biomass and gross primary productivity but no effect of sensitive genotypes, this result stemming from genotype-specific differences in population growth in the presence of toxic prey. The former effect was as large as effects seen in previous Daphnia manipulations at similar productivity levels. Thus, we demonstrated that the effect of consumer genotypes with contrasting offensive adaptations was as large as the effect of consumer presence/absence.
authors.affiliation: Department of Fisheries and Allied Aquacultures, Auburn University, Auburn, Alabama 36849, USA.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Chislock
authors.affiliation: Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Orlando
authors.initials: O
authors.lastname: Sarnelle
authors.affiliation: Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Brianna K
authors.initials: BK
authors.lastname: Olsen
authors.affiliation: Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Enrique
authors.initials: E
authors.lastname: Doster
authors.affiliation: Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Alan E
authors.initials: AE
authors.lastname: Wilson
mesh_terms: D000818:Animals; D018533:Biomass; D000458:Cyanobacteria / Q000502:physiology*; D003621:Daphnia / Q000235:genetics* / Q000502:physiology; D017753:Ecosystem; D060434:Herbivory