title: Soil fungal effects on floral signals, rewards, and aboveground interactions in an alpine pollination web.
abstract: OBJECTIVE
  Plants interact with above- and belowground organisms; the combined effects of these interactions determine plant fitness and trait evolution. To better understand the ecological and evolutionary implications of multispecies interactions, we explored linkages between soil fungi, pollinators, and floral larcenists in Polemonium viscosum (Polemoniaceae).
  
  
  METHODS
  Using a fungicide, we experimentally reduced fungal colonization of krummholz and tundra P. viscosum in 2008-2009. We monitored floral signals and rewards, interactions with pollinators and larcenists, and seed set for fungicide-treated and control plants.
  
  
  RESULTS
  Fungicide effects varied among traits, between interactions, and with environmental context. Treatment effects were negligible in 2008, but stronger in 2009, especially in the less-fertile krummholz habitat. There, fungicide increased nectar sugar content and damage by larcenist ants, but did not affect pollination. Surprisingly, fungicide also enhanced seed set, suggesting that direct resource costs of soil fungi exceed indirect benefits from reduced larceny. In the tundra, fungicide effects were negligible in both years. However, pooled across treatments, colonization by mycorrhizal fungi in 2009 correlated negatively with the intensity and diversity of floral volatile organic compounds, suggesting integrated above- and belowground signaling pathways.
  
  
  CONCLUSIONS
  Fungicide effects on floral rewards in P. viscosum link soil fungi to ecological costs of pollinator attraction. Trait-specific linkages to soil fungi should decouple expression of sensitive and buffered floral phenotypes in P. viscosum. Overall, this study demonstrates how multitrophic linkages may lead to shifting selection pressures on interaction traits, restricting the evolution of specialization.
authors.affiliation: Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211, USA. kbecklin@ku.edu
authors.forename: Katie M
authors.initials: KM
authors.lastname: Becklin
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Gamez
authors.forename: Bryan
authors.initials: B
authors.lastname: Uelk
authors.forename: Robert A
authors.initials: RA
authors.lastname: Raguso
authors.forename: Candace
authors.initials: C
authors.lastname: Galen
mesh_terms: D000818:Animals; D001000:Ants / Q000502:physiology; D005075:Biological Evolution; D004463:Ecology; D017753:Ecosystem; D035264:Flowers / Q000737:chemistry / Q000502:physiology*; D005659:Fungicides, Industrial / Q000494:pharmacology; D056084:Genetic Fitness; D019684:Magnoliopsida / Q000737:chemistry / Q000382:microbiology* / Q000502:physiology; D038821:Mycorrhizae / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D010641:Phenotype; D011058:Pollen / Q000502:physiology; D054817:Pollination; D012639:Seeds / Q000502:physiology; D015398:Signal Transduction; D012988:Soil Microbiology; D013559:Symbiosis; D055549:Volatile Organic Compounds / Q000737:chemistry
chemical_list: D005659:Fungicides, Industrial; D055549:Volatile Organic Compounds