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Insectes Sociaux

, Volume 63, Issue 4, pp 531–541 | Cite as

Distribution and origin of intraspecific social variation in the California harvester ant Pogonomyrmex californicus

  • R. OversonEmail author
  • J. Fewell
  • J. Gadau
Research Article

Abstract

The California seed harvester ant Pogonomyrmex californicus exhibits striking differences in queen behavior and colony organization throughout its range. Most populations show the likely ancestral condition of single-queen colonies (monogyny). However, in one known population, cooperation between queens during colony founding (pleometrosis) occurs, and is suspected to persist to the mature colony stage (primary polygyny). To better understand this variation in social phenotype, we estimate relatedness among co-foundresses, measure the frequency of polygyny in adult colonies across three focal populations, and assess population genetic structure between populations. We additionally measure queen mating frequency (polyandry) across focal populations. With few possible exceptions, queens within pleometrotic associations are unrelated. We demonstrate a correlation between pleometrosis in incipient colonies and polygyny in adult colonies at the population level. Nuclear microsatellites and mtDNA barcoding indicate significant structure between focal populations. Queens from all three focal populations engage in relatively high levels of polyandry. These findings, when examined with previous data demonstrating that pleometrosis leads to polygynous colonies in the laboratory, strongly suggest that the same occurs in nature. However, the possibility of additional queen adoption in adult colonies (secondary polygyny) is not excluded. Thus, polygynous P. californicus colonies potentially represent long-term associations of unrelated family groups, containing multiple unrelated queens and their mixed-paternity offspring. Due to its pronounced variation in social behavior, P. californicus provides a unique opportunity to examine the evolutionary history and genetic underpinnings of cooperation among non-relatives, a strategy of intense interest in behavioral ecology.

Keywords

Pogonomyrmex Primary polygyny Pleometrosis Cooperation Population genetics Biogeography 

Notes

Acknowledgments

We would like to thank Tresa Marchi and Danielle Sensenig, who worked tirelessly and efficiently at genotyping samples. Robert A. Johnson, C. Tate Holbrook, Joshua D. Gibson, and Brendon Mott provided samples. Bert Hölldobler provided valuable contributions to the development of ideas leading to this study. We would also like to thank two anonymous reviewers for their thorough feedback which strongly improved this manuscript.

Supplementary material

40_2016_497_MOESM1_ESM.docx (71 kb)
Supplementary material 1 (DOCX 71 kb)

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Copyright information

© International Union for the Study of Social Insects (IUSSI) 2016

Authors and Affiliations

  1. 1.Chicago Botanic GardenGlencoeUSA
  2. 2.School of Life Sciences and Center for Social Dynamics and ComplexityArizona State UniversityTempeUSA

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