title: Hairiness: the missing link between pollinators and pollination.
abstract: BACKGROUND
  Functional traits are the primary biotic component driving organism influence on ecosystem functions; in consequence, traits are widely used in ecological research. However, most animal trait-based studies use easy-to-measure characteristics of species that are at best only weakly associated with functions. Animal-mediated pollination is a key ecosystem function and is likely to be influenced by pollinator traits, but to date no one has identified functional traits that are simple to measure and have good predictive power.
  
  
  METHODS
  Here, we show that a simple, easy to measure trait (hairiness) can predict pollinator effectiveness with high accuracy. We used a novel image analysis method to calculate entropy values for insect body surfaces as a measure of hairiness. We evaluated the power of our method for predicting pollinator effectiveness by regressing pollinator hairiness (entropy) against single visit pollen deposition (SVD) and pollen loads on insects. We used linear models and AICCmodel selection to determine which body regions were the best predictors of SVD and pollen load.
  
  
  RESULTS
  We found that hairiness can be used as a robust proxy of SVD. The best models for predicting SVD for the flower speciesBrassica rapaandActinidia deliciosawere hairiness on the face and thorax as predictors (R2= 0.98 and 0.91 respectively). The best model for predicting pollen load forB.rapawas hairiness on the face (R2= 0.81).
  
  
  CONCLUSIONS
  We suggest that the match between pollinator body region hairiness and plant reproductive structure morphology is a powerful predictor of pollinator effectiveness. We show that pollinator hairiness is strongly linked to pollination-an important ecosystem function, and provide a rigorous and time-efficient method for measuring hairiness. Identifying and accurately measuring key traits that drive ecosystem processes is critical as global change increasingly alters ecological communities, and subsequently, ecosystem functions worldwide.
authors.affiliation: Centre for Biodiversity and Biosecurity, School of Biological Sciences, The University of Auckland , Auckland , New Zealand.
authors.forename: Jamie R
authors.initials: JR
authors.lastname: Stavert
authors.affiliation: Instituto de Microelectrónica de Sevilla CSIC/Universidad de Sevilla , Sevilla , Spain.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Liñán-Cembrano
authors.affiliation: Centre for Biodiversity and Biosecurity, School of Biological Sciences, The University of Auckland , Auckland , New Zealand.
authors.forename: Jacqueline R
authors.initials: JR
authors.lastname: Beggs
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited , Christchurch , New Zealand.
authors.forename: Brad G
authors.initials: BG
authors.lastname: Howlett
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited , Hamilton , New Zealand.
authors.forename: David E
authors.initials: DE
authors.lastname: Pattemore
authors.affiliation: Integrative Ecology Department, Estación Biológica de Doñana (EBD-CSIC) , Sevilla , Spain.
authors.forename: Ignasi
authors.initials: I
authors.lastname: Bartomeus
keywords: Ecosystem function; Entropy; Functional trait; Image analysis; Pilosity; Pollen deposition; Pollen load; Pollination; SVD