Opposing patterns of altitude-driven pollinator turnover in the tropical and temperate Americas

Agnes Sophie Dellinger, Ashley M. Hamilton, Carolyn A. Wessinger, Stacey Smith

Publications: Contribution to journalArticlePeer Reviewed


Abiotic factors (e.g., temperature, precipitation) vary markedly along elevational gradients and differentially affect major groups of pollinators. Ectothermic bees, for example, are impeded in visiting flowers by cold and rainy conditions common at high elevations, while endothermic hummingbirds may continue forag-ing under such conditions. Despite the possibly far-reaching effects of the abiotic environment on plant-pollinator interactions, we know little about how these factors play out at broad ecogeographic scales. We address this knowledge gap by investigating how pollination systems vary across elevations in 26 plant clades from the Americas. Specifically, we explore Cruden’s 1972 hypothesis that the harsh montane environment drives a turnover from insect to vertebrate pollination at higher elevations. We compared the elevational distribution and bioclimatic attributes for a total of 2,232 flowering plants and found that Cruden’s hypothesis holds only in the tropics. Above 307N and below 307S, plants pollinated by vertebrates (mostly hum-mingbirds) tend to occur at lower elevations than those pollinated by insects. We hypothesize that this latitudinal transition is due to the distribution of moist, forested habitats favored by vertebrate pol-linators, which are common at high elevations in the tropics but not in the temperate Americas.

Original languageEnglish
Pages (from-to)152-165
Number of pages14
JournalThe American Naturalist: a bi-monthly journal devoted to the advancement and correlation of the biological sciences
Issue number2
Early online date2023
Publication statusPublished - 1 Aug 2023

Austrian Fields of Science 2012

  • 106008 Botany
  • 106012 Evolutionary research
  • 106042 Systematic botany


  • Altitudinal gradient
  • hummingbird habitats
  • pollinator shift
  • precipitation
  • altitudinal gradient

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