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Intraspecific support for the polygyny-vs.-polyandry hypothesis in the bulldog ant Myrmecia brevinoda

Authors

  • ZENG-QIANG QIAN,

    1. School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia
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  • HELGE SCHLÜNS,

    1. School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia
    2. Department of Apiculture, University of Agricultural Sciences and Veterinary Medicine, 400372 Cluj-Napoca, Romania
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    • These authors contributed equally to the paper.

  • BIRGIT C. SCHLICK-STEINER,

    1. Molecular Ecology Group, Institute of Ecology, University of Innsbruck, 6020 Innsbruck, Austria
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    • These authors contributed equally to the paper.

  • FLORIAN M. STEINER,

    1. Molecular Ecology Group, Institute of Ecology, University of Innsbruck, 6020 Innsbruck, Austria
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    • These authors contributed equally to the paper.

  • SIMON K. A. ROBSON,

    1. School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia
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    • These authors contributed equally to the paper.

  • ELLEN A. SCHLÜNS,

    1. School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia
    2. Department of Apiculture, University of Agricultural Sciences and Veterinary Medicine, 400372 Cluj-Napoca, Romania
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    • These authors contributed equally to the paper.

  • ROSS H. CROZIER

    1. School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia
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    • Prof Ross H. Crozier deceased on 12 November 2009.


Zeng-Qiang Qian, Fax: +61 7 4725 1570; E-mail: zengqiang.qian@yahoo.com

Abstract

The number of queens per colony and the number of matings per queen are the most important determinants of the genetic structure of ant colonies, and understanding their interrelationship is essential to the study of social evolution. The polygyny-vs.-polyandry hypothesis argues that polygyny and polyandry should be negatively associated because both can result in increased intracolonial genetic variability and have costs. However, evidence for this long-debated hypothesis has been lacking at the intraspecific level. Here, we investigated the colony genetic structure in the Australian bulldog ant Myrmecia brevinoda. The numbers of queens per colony varied from 1 to 6. Nestmate queens within polygynous colonies were on average related (rqq = 0.171 ± 0.019), but the overall relatedness between queens and their mates was indistinguishable from zero (rqm = 0.037 ± 0.030). Queens were inferred to mate with 1–10 males. A lack of genetic isolation by distance among nests indicated the prevalence of independent colony foundation. In accordance with the polygyny-vs.-polyandry hypothesis, the number of queens per colony was significantly negatively associated with the estimated number of matings (Spearman rank correlation = −0.490, = 0.028). This study thus provides the rare intraspecific evidence for the polygyny-vs.-polyandry hypothesis. We suggest that the high costs of multiple matings and the strong effect of multiple mating on intracolonial genetic diversity may be essential to the negative association between polygyny and polyandry and that any attempt to empirically test this hypothesis should place emphasis upon these two key underlying aspects.

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