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dc.contributor.authorCronin, Gregen_US
dc.contributor.authorHay, Mark E.en_US
dc.date.accessioned2011-08-31T19:57:57Z
dc.date.available2011-08-31T19:57:57Z
dc.date.issued1996-07
dc.identifier.citationCronin, G. and M.E. Hay. 1996. Susceptibility to herbivores depends on recent history of both the plant and animal. Ecology 77: 1531-1543.en_US
dc.identifier.issn0012-9658
dc.identifier.urihttp://hdl.handle.net/1853/40773
dc.descriptionDOI: 10.2307/2265549en_US
dc.description©1996 Ecological Society of Americaen_US
dc.description.abstractPhysical stress to seaweeds and hunger stress of herbivores can influence the outcome of chemically mediated seaweed—herbivore interactions. The unpalatable brown seaweed Dictyota ciliolata produces the diterpenoid secondary metabolites pachydictyol A, dictyol B acetate, and dictyodial. At natural concentrations, pachydictyol A deterred the sea urchin Arbacia punctulata but did not inhibit feeding by the pinfish Lagodon rhomboides or the amphipod Ampithoe longimana until concentrations were 2.5—5 times natural levels. Dictyol B acetate deterred the urchin, amphipod, and pinfish at, or far below, natural concentrations. Dictyodial was too unstable to assay directly, but indirect experiments suggested that natural concentrations deterred the urchin, but not the pinfish or amphipod. Mild desiccation of D. ciliolata reduced concentrations of the different secondary metabolites by 7—38% and plants became 2.6—3.4 times more susceptible to urchin and amphipod grazing. The combined concentrations of pachydictyol A and dictyol B acetate found in undesiccated Dictyota ciliolata deterred feeding by urchins, but this deterrent effect was lost at concentrations found in the desiccated plants. Desiccated and undesiccated plants did not differ in nutritive value (as measured by protein and total N content) or toughness. Thus, desiccated plants became more palatable because chemical defenses were lost, not because nutritive value was increased. The stress of near—surface ultraviolet radiation also caused significant physiological changes in Dictyota ciliolata. UV—exposed blades bleached, senesced, and grew 84% less than blades protected from UV radiation. Tissue loss and minimal growth of UV—stressed plants constrained our sample sizes, but the limited assays that could be run suggested that UV stress may lower chemical defenses and increase plant susceptibility to herbivores. Because many previous investigations of herbivore feeding patterns used animals that had been starved for days before an assay, we tested the effects of this commonly used procedure on feeding discrimination. Recently fed urchins always avoided food containing natural concentrations of pachydictyol A during separate feeding trials performed on each of four consecutive days. In contrast, urchins deprived of food for 3 d before this assay did not avoid the treated food on days 1 and 2 of feeding trials, but did avoid it on days 3 and 4 after their hunger was reduced by feeding during days 1 and 2. If we had used only starved urchins (a common procedure in previous investigations), we could have concluded, with apparent justification, that urchins were unaffected by pachydictyol A (if the assays were run for only 1—2 d) or that they needed 2 d of exposure to the compound in order to learn to avoid it. Both of these conclusions would have been incorrect.en_US
dc.language.isoen_USen_US
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectAmpithoeen_US
dc.subjectArbaciaen_US
dc.subjectChemical defenseen_US
dc.subjectDesiccationen_US
dc.subjectDictyotaen_US
dc.subjectFeeding behavioren_US
dc.subjectLagodonen_US
dc.subjectPlant-herbivore interactionen_US
dc.subjectStress-induced changesen_US
dc.subjectUV radiationen_US
dc.titleSusceptibility to herbivores depends on recent history of both the plant and animalen_US
dc.typeArticleen_US
dc.contributor.corporatenameUniversity of North Carolina at Chapel Hill. Institute of Marine Sciencesen_US
dc.publisher.originalEcological Society of Americaen_US
dc.identifier.doi10.2307/2265549


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