Arms races and the evolution of big fierce societies

G P Boswell, N R Franks, N F Britton

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The causes of biological gigantism have received much attention, but only for individual organisms. What selection pressures might favour the evolution of gigantic societies? Here we consider the largest single-queen insect societies, those of the Old World army ant Dorylus, single colonies of which can have 20 million workers. We propose that colony gigantism in Dorylus arises as a result of an arms race and test this prediction by developing a size-structured mathematical model. We use this model for exploring and potentially explaining differences in colony size, colony aggression and colony propagation strategies in populations of New World army ants Eciton and Old World army ants Dorylus. The model shows that, by determining evolutionarily stable strategies (ESSs), differences in the trophic levels at which these army ants live feed forwards into differences in their densities and collision rates and. hence, into different strategies of growth, aggression and propagation. The model predicts large colony size and the occurrence, propagation strategy of battles and a colony-propagation strategy involving highly asymmetrical divisions in Dorylus and that Eciton colonies should be smaller, non-combative and exhibit equitable binary fission. These ESSs are in excellent agreement with field observations and demonstrate that gargantuan societies can arise through arms races.
Original languageEnglish
Pages (from-to)1723-1730
Number of pages8
JournalProceedings of the Royal Society B: Biological Sciences
Volume268
Issue number1477
Publication statusPublished - 2001

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Dorylus
arms race
Ants
Formicidae
Eciton
Gigantism
evolutionarily stable strategy
Aggression
ant
aggression
insect colonies
live feeds
queen insects
Mathematical models
Insects
Theoretical Models
mathematical models
Pressure
prediction
society

Keywords

  • arms race
  • strategies
  • KENYA
  • BLUE WHALES
  • POPULATIONS
  • mathematical model
  • Eciton
  • CALIFORNIA
  • MODEL
  • REPRODUCTION
  • Dorylus
  • MIGRATION
  • ANTS
  • evolutionarily stable
  • NESTS
  • gigantism

Cite this

Arms races and the evolution of big fierce societies. / Boswell, G P; Franks, N R; Britton, N F.

In: Proceedings of the Royal Society B: Biological Sciences, Vol. 268, No. 1477, 2001, p. 1723-1730.

Research output: Contribution to journalArticle

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