Aposematic Coloration of Moths Decreases Strongly along an Elevational Gradient in the Andes

Konrad Fiedler, Gunnar Brehm

Publications: Contribution to journalArticlePeer Reviewed

Abstract

On tropical mountains, predation pressure decreases with elevation. Accordingly, one expects an elevational decay in the prevalence of costly defensive traits such as aposematic coloration. Using light-trap catches of Arctiinae moths (353 species, 4466 individuals), assembled along a forested gradient in the megadiverse tropical Andes of southern Ecuador, we show that the incidence of aposematic coloration decreases strongly between 1040 and 2670 m asl. While over 60% of Arctiinae moths were warningly colored at lowest sites, this fraction decreased to less than 20% in montane forest, yet increased slightly again at the highest sites in the very open Purdiaea nutans forest. In parallel, the incidence of hymenopteran mimics and of species that mimic chemically defended beetles decreased with elevation. Hymenopteran mimics accounted for less than 5% of Arctiinae moths at sites above 2100 m, and beetle mimics were essentially lacking at high elevations. These patterns coincide with a change in gross taxonomic composition of Arctiinae ensembles and with an increase in average body size towards higher elevations. Representatives of Euchromiina and Ctenuchina became scarce with altitude, whereas the prevalence of Lithosiinae increased. Our findings suggest that the variable selective pressures along the elevational gradient favor warning coloration primarily at lower sites, whereas cryptic appearance of adult moths dominates in the tropical upper montane forest.
Original languageEnglish
Article number903
Number of pages13
JournalInsects
Volume12
Issue number10
DOIs
Publication statusPublished - 3 Oct 2021

Austrian Fields of Science 2012

  • 106047 Animal ecology
  • 106003 Biodiversity research

Keywords

  • ASSEMBLAGES
  • DIVERSITY
  • INCREASES
  • LEPIDOPTERA
  • MIMICRY
  • PREY
  • RAIN-FOREST
  • defensive coloration
  • elevational gradient
  • predation risk
  • tiger moths
  • tropical Andes
  • Defensive coloration
  • Tiger moths
  • Tropical andes
  • Elevational gradient
  • Predation risk

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