title: Armament imbalances: match and mismatch in plant-pollinator traits of highly specialized long-spurred orchids.
abstract: BACKGROUND
  Some species of long-spurred orchids achieve pollination by a close association with long-tongued hawkmoths. Among them, several Habenaria species present specialized mechanisms, where pollination success depends on the attachment of pollinaria onto the heads of hawkmoths with very long proboscises. However, in the Neotropical region such moths are less abundant than their shorter-tongued relatives and are also prone to population fluctuations. Both factors may give rise to differences in pollinator-mediated selection on floral traits through time and space.
  
  
  RESULTS
  We characterized hawkmoth assemblages and estimated phenotypic selection gradients on orchid spur lengths in populations of three South American Habenaria species. We examined the match between hawkmoth proboscis and flower spur lengths to determine whether pollinators may act as selective agents on flower morphology. We found significant directional selection on spur length only in Habenaria gourlieana, where most pollinators had proboscises longer than the mean of orchid spur length.
  
  
  CONCLUSIONS
  Phenotypic selection is dependent on the mutual match between pollinator and flower morphologies. However, our findings indicate that pollinator-mediated selection may vary through time and space according to local variations in pollinator assemblages.
authors: Laboratorio de Ecología Evolutiva y Biología Floral, Instituto Multidisciplinario de Biología Vegetal, Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Córdoba, Córdoba, Argentina.
authors: Marcela
authors: M
authors: Moré
authors: Felipe W
authors: FW
authors: Amorim
authors: Santiago
authors: S
authors: Benitez-Vieyra
authors: A Martin
authors: AM
authors: Medina
authors: Marlies
authors: M
authors: Sazima
authors: Andrea A
authors: AA
authors: Cocucci
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D007915:Lepidoptera / Q000033:anatomy & histology* / Q000502:physiology*; D029595:Orchidaceae / Q000033:anatomy & histology* / Q000502:physiology*; D010641:Phenotype; D054817:Pollination; D012641:Selection, Genetic; D014059:Tongue / Q000033:anatomy & histology