Sexual size dimorphism and sex ratios in dragonflies (Odonata)

Frank Johansson, Philip H. Crowley, Tomas Brodin

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

Sexual size dimorphism and biased sex ratios are common in animals. Rensch's rule states that sexual size dimorphism (SSD) would increase with body size in taxa where males are larger than females and decrease with body size in taxa where females are larger. We tested this trend in dragonflies (Odonata) by analysing body size of 21 species and found support for Rensch's rule. The increase in SSD with increasing size among species can be explained by sexual selection favouring large males. We also estimated the slope of the relationship between sex ratio and size ratio in populations of the 21 species. A negative slope would suggest that the larger sex suffers from high mortality in the larval stage, consistent with riskier foraging. The slope of this relationship was negative, but after correcting for phylogentic non-independence with independent contrasts the relationship was no longer statistically significant, perhaps because of phylogenic inertia or low sample size.

Original languageEnglish
Pages (from-to)507-513
Number of pages7
JournalBiological Journal of the Linnean Society
Volume86
Issue number4
DOIs
StatePublished - Dec 2005

Keywords

  • Body size
  • Foraging risk
  • Insects
  • Life history
  • Rensch's rule

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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