Atmospheric oxygen level and the evolution of insect body size

Jon Harrison, Alexander Kaiser, John M. VandenBrooks

Research output: Contribution to journalReview article

108 Scopus citations

Abstract

Insects are small relative to vertebrates, possibly owing to limitations or costs associated with their blindended tracheal respiratory system. The giant insects of the late Palaeozoic occurred when atmospheric PO2 (aPO2) was hyperoxic, supporting a role for oxygen in the evolution of insect body size. The paucity of the insect fossil record and the complex interactions between atmospheric oxygen level, organisms and their communities makes it impossible to definitively accept or reject the historical oxygen-size link, and multiple alternative hypotheses exist. However, a variety of recent empirical findings support a link between oxygen and insect size, including: (i) most insects develop smaller body sizes in hypoxia, and some develop and evolve larger sizes in hyperoxia; (ii) insects developmentally and evolutionarily reduce their proportional investment in the tracheal system when living in higher aPO2, suggesting that there are significant costs associated with tracheal system structure and function; and (iii) larger insects invest more of their body in the tracheal system, potentially leading to greater effects of aPO2 on larger insects. Together, these provide a wealth of plausible mechanisms by which tracheal oxygen delivery may be centrally involved in setting the relatively small size of insects and for hyperoxia-enabled Palaeozoic gigantism.

Original languageEnglish (US)
Pages (from-to)1937-1946
Number of pages10
JournalProceedings of the Royal Society B: Biological Sciences
Volume277
Issue number1690
DOIs
StatePublished - Jul 7 2010

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Keywords

  • Body size
  • Evolution
  • Gigantism
  • Oxygen

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)

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