title: Hybridization in East African swarm-raiding army ants.
abstract: BACKGROUND
  Hybridization can have complex effects on evolutionary dynamics in ants because of the combination of haplodiploid sex-determination and eusociality. While hybrid non-reproductive workers have been found in a range of species, examples of gene-flow via hybrid queens and males are rare. We studied hybridization in East African army ants (Dorylus subgenus Anomma) using morphology, mitochondrial DNA sequences, and nuclear microsatellites.
  
  
  RESULTS
  While the mitochondrial phylogeny had a strong geographic signal, different species were not recovered as monophyletic. At our main study site at Kakamega Forest, a mitochondrial haplotype was shared between a "Dorylus molestus-like" and a "Dorylus wilverthi-like" form. This pattern is best explained by introgression following hybridization between D. molestus and D. wilverthi. Microsatellite data from workers showed that the two morphological forms correspond to two distinct genetic clusters, with a significant proportion of individuals being classified as hybrids.
  
  
  CONCLUSIONS
  We conclude that hybridization and gene-flow between the two army ant species D. molestus and D. wilverthi has occurred, and that mating between the two forms continues to regularly produce hybrid workers. Hybridization is particularly surprising in army ants because workers have control over which males are allowed to mate with a young virgin queen inside the colony.
authors.affiliation: Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark.|Laboratory of Insect Social Evolution, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
authors.forename: Daniel Jc
authors.initials: DJ
authors.lastname: Kronauer
authors.affiliation: Zoological Research Museum Alexander Koenig, Adenauerallee 160, 53113 Bonn, Germany.|Department of Animal Ecology and Tropical Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
authors.forename: Marcell K
authors.initials: MK
authors.lastname: Peters
authors.affiliation: Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark.|Länderinstitut für Bienenkunde, Friedrich-Engels-Strasse 32, 16540 Hohen Neuendorf, Germany.
authors.forename: Caspar
authors.initials: C
authors.lastname: Schöning
authors.affiliation: Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark.
authors.forename: Jacobus J
authors.initials: JJ
authors.lastname: Boomsma