title: Effects of plant intraspecific diversity across three trophic levels: Underlying mechanisms and plant traits.
abstract: OBJECTIVE
  Although there is increasing recognition of the effects of plant intraspecific diversity on consumers, the mechanisms by which such effects cascade-up to higher trophic levels remain elusive.
  
  
  METHODS
  We evaluated the effects of plant (lima bean, Phaseolus lunatus) intraspecific diversity on a suite of insect herbivores (leaf-chewers, aphids, and seed-eating beetles) and their third trophic-level associates (parasitoids and aphid-tending ants). We established plots of three plants, classified as monocultures of one population source or polycultures with mixtures of three of the four population sources (N = 16 plots per level of diversity). Within each plot, plants were individually placed in pots and canopy contact was prevented, therefore eliminating diversity effects on consumers arising from changes in plant traits due to plant physical interactions.
  
  
  RESULTS
  Plant diversity reduced damage by leaf-chewers as well as aphid abundance, and the latter effect in turn reduced ant abundance. In contrast, plant diversity increased the abundance of seed-eating beetles, but did not influence their associated parasitoids. There were no effects of diversity on seed traits potentially associated with seed predation, suggesting that differences in early season herbivory between monocultures and polycultures (a likely mechanism of diversity effects on plants since plant interactions were prevented) did not drive concomitant changes in plant traits.
  
  
  CONCLUSIONS
  This study emphasizes that effects of plant intraspecific diversity on consumers are contingent upon differences in associate responses within and among higher trophic levels and suggests possible mechanisms by which such effects propagate up this food web.
authors.affiliation: Departamento de Ecología Tropical, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán. Km. 15.5 Carretera Mérida-Xmatkuil. 97000. Mérida, Yucatán, México.
authors.forename: Luis
authors.initials: L
authors.lastname: Abdala-Roberts
authors.affiliation: Department of Entomology, Rutgers University, P.E. Marucci Center, Chatsworth, New Jersey 08019, USA.
authors.forename: Johnattan
authors.initials: J
authors.lastname: Hernández-Cumplido
authors.affiliation: Facultad de Ingeniería Química, Universidad Autónoma de Yucatán. Periférico Norte, Km. 33.5, Colonia Chuburná de Hidalgo Inn. 97203. Mérida, Yucatán, México.
authors.forename: Luis
authors.initials: L
authors.lastname: Chel-Guerrero
authors.affiliation: Facultad de Ingeniería Química, Universidad Autónoma de Yucatán. Periférico Norte, Km. 33.5, Colonia Chuburná de Hidalgo Inn. 97203. Mérida, Yucatán, México.
authors.forename: David
authors.initials: D
authors.lastname: Betancur-Ancona
authors.affiliation: Institute of Biology, Laboratory of Evolutionary Entomology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland xmoreira1@gmail.com betty.benrey@unine.ch.
authors.forename: Betty
authors.initials: B
authors.lastname: Benrey
authors.affiliation: Misión Biológica de Galicia (MBG-CSIC), Apdo. 28 36080 Pontevedra, Galicia, Spain xmoreira1@gmail.com betty.benrey@unine.ch.
authors.forename: Xoaquín
authors.initials: X
authors.lastname: Moreira
mesh_terms: D000818:Animals; D044822:Biodiversity; D020387:Food Chain; D060434:Herbivory; D007313:Insecta / Q000469:parasitology* / Q000502:physiology*; D027805:Phaseolus / Q000235:genetics / Q000502:physiology*
keywords: herbivory; lima bean; parasitism; plant intraspecific diversity; plant-mediated effects; tri-trophic interactions