Nature 435, 1230-1234 (30 June 2005) | doi:10.1038/nature03705; Received 5 February 2005; Accepted 4 May 2005

Clonal reproduction by males and females in the little fire ant

Denis Fournier1,6,7, Arnaud Estoup1,6, Jérôme Orivel2, Julien Foucaud1, Hervé Jourdan3, Julien Le Breton4 & Laurent Keller5

  1. Centre de Biologie et de Gestion des Populations, INRA, Campus International de Baillarguet, CS 30 016, 34988 Montferrier/Lez Cedex, France
  2. Laboratoire Évolution et Diversité Biologique, UMR-CNRS 5174, Université Toulouse III, 118 route de Narbonne, 31062 Toulouse cedex 4, France
  3. Laboratoire de Zoologie Appliquée, IRD, 98948 Nouméa, Nouvelle-Calédonie
  4. Laboratory of Sub-Tropical Zoology, University of the Ryukyus, 903-0213 Nishihara, Okinawa, Japan
  5. Department of Ecology and Evolution, Bâtiment de Biologie, University of Lausanne, 1015 Lausanne, Switzerland
  6. *These authors contributed equally to this work
  7. †Present address: Behavioral and Evolutionary Ecology – CP 160/12, Université Libre de Bruxelles, 50 avenue F. D. Roosevelt, 1050 Brussels, Belgium

Correspondence to: Denis Fournier1,6,7Arnaud Estoup1,6 Correspondence and requests for materials should be addressed to D.F. (Email: denis.fournier@ulb.ac.be) or A.E. (Email: estoup@ensam.inra.fr).

Sexual reproduction can lead to major conflicts between sexes and within genomes1, 2, 3, 4. Here we report an extreme case of such conflicts in the little fire ant Wasmannia auropunctata. We found that sterile workers are produced by normal sexual reproduction, whereas daughter queens are invariably clonally produced. Because males usually develop from unfertilized maternal eggs in ants and other haplodiploid species, they normally achieve direct fitness only through diploid female offspring. Hence, although the clonal production of queens increases the queen's relatedness to reproductive daughters, it potentially reduces male reproductive success to zero. In an apparent response to this conflict between sexes, genetic analyses reveal that males reproduce clonally, most likely by eliminating the maternal half of the genome in diploid eggs. As a result, all sons have nuclear genomes identical to those of their father. The obligate clonal production of males and queens from individuals of the same sex effectively results in a complete separation of the male and female gene pools. These findings show that the haplodiploid sex-determination system provides grounds for the evolution of extraordinary genetic systems and new types of sexual conflict.