Caste determination in a polymorphic social insect: Nutritional, social, and genetic factors

C. R. Smith, K. E. Anderson, C. V. Tillberg, Juergen Gadau, A. V. Suarez

Research output: Contribution to journalArticlepeer-review

91 Scopus citations


We examined how dietary, social, and genetic factors affect individual size and caste in the Florida harvester ant Pogonomyrmex badius, which has three discrete female castes. The diet that a larva consumed, as indicated by δ13C, δ15N, and C:N, varied with caste. Both N content and estimated trophic position of dietary input was higher for major than for minor workers and was highest for gynes (reproductive females). The size and resources of a colony affected the size of only minor workers, not that of gynes and major workers. Approximately 19% of patrilines showed a bias in which female caste they produced. There were significant genetic effects on female size, and the average sizes of a major worker and a gyne produced by a patriline were correlated, but neither was correlated with minor worker size. Thus, genetic factors influence both caste and size within caste. We conclude that environmental, social, and genetic variation interact to create morphological and physiological variation among females in P. badius. However, the relative importance of each type of factor affecting caste determination is caste specific.

Original languageEnglish (US)
Pages (from-to)497-507
Number of pages11
JournalAmerican Naturalist
Issue number4
StatePublished - Oct 2008


  • Ant
  • Diet
  • Environmental
  • Genetic
  • Pogonomyrmex
  • Stable isotope

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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