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Clonal reproduction by males and females in the little fire ant

Abstract

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.

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Acknowledgements

We are grateful to the Laboratoire Environment de Petit Saut (EDF-CNEH) for hosting us during field work, the Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD) of French Guiana for allowing access to plantations, S. Aron for performing flow cytometry analysis, and M. Chapuisat, P. Christe, D. Haig, R. Hammond, S. Helms Cahan, K. Parker and D. Queller for comments on the manuscript. The work was supported by grants from the French Ministère de l'Écologie et du Développement Durable to A.E. and the Swiss NSF to L.K.

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Correspondence to Denis Fournier or Arnaud Estoup.

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Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

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Figure 1: Site and nest locations.
Figure 2: Neighbour-joining dendrogram of the genetic (allele-shared) distances between queens (Q), gynes (G) and male sperms (M) collected over all the five sites (A–E).
Figure 3

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