Transitioning from unstable to stable colony growth in the desert leafcutter ant Acromyrmex versicolor

Rebecca M. Clark, Jennifer Fewell

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Like organisms, cohesive social groups such as insect colonies grow from a few individuals to large and complex integrated systems. Growth is driven by the interplay between intrinsic growth rates and environmental factors, particularly nutritional input. Ecologically inspired population growth models assume that this relationship remains constant until maturity, but more recent models suggest that it should be less stable at small colony sizes. To test this empirically, we monitored worker population growth and fungal development in the desert leafcutter ant, Acromyrmex versicolor, over the first 6 months of colony development. As a multitrophic, symbiotic system, leafcutter colonies must balance efforts to manage both fungus production and the growth of the ants consuming it. Both ants and fungus populations grew exponentially, but the shape of this relationship transitioned at a size threshold of 89 ± 9 workers. Above this size, colony mortality plummeted and colonies shifted from hypometric to hypermetric growth, with a distinct stabilization of the relationship between the worker population and fungus. Our findings suggest that developing colonies undergo key changes in organizational structure and stability as they grow, with a resulting positive transition in efficiency and robustness.

Original languageEnglish (US)
Pages (from-to)163-171
Number of pages9
JournalBehavioral Ecology and Sociobiology
Volume68
Issue number1
DOIs
StatePublished - Jan 1 2014

Keywords

  • Acromyrmex
  • Colony growth
  • Development
  • Division of labor
  • Leafcutter ant
  • Social allometry

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology

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