title: Interaction specificity between leaf-cutting ants and vertically transmitted Pseudonocardia bacteria.
abstract: BACKGROUND
  The obligate mutualism between fungus-growing ants and microbial symbionts offers excellent opportunities to study the specificity and stability of multi-species interactions. In addition to cultivating fungus gardens, these ants have domesticated actinomycete bacteria to defend gardens against the fungal parasite Escovopsis and possibly other pathogens. Panamanian Acromyrmex echinatior leaf-cutting ants primarily associate with actinomycetes of the genus Pseudonocardia. Colonies are inoculated with one of two vertically transmitted phylotypes (Ps1 or Ps2), and maintain the same phylotype over their lifetime. We performed a cross-fostering experiment to test whether co-adaptations between ants and bacterial phylotypes have evolved, and how this affects bacterial growth and ant prophylactic behavior after infection with Escovopsis.
  
  
  RESULTS
  We show that Pseudonocardia readily colonized ants irrespective of their colony of origin, but that the Ps2 phylotype, which was previously shown to be better able to maintain its monocultural integrity after workers became foragers than Ps1, reached a higher final cover when grown on its native host than on alternative hosts. The frequencies of major grooming and weeding behaviors co-varied with symbiont/host combinations, showing that ant behavior also was affected when cuticular actinomycete phylotypes were swapped.
  
  
  CONCLUSIONS
  These results show that the interactions between leaf-cutting ants and Pseudonocardia bear signatures of mutual co-adaptation within a single ant population.
authors.affiliation: Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark. sandrabreumandersen@gmail.com.|Current address: Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark. sandrabreumandersen@gmail.com.
authors.forename: Sandra B
authors.initials: SB
authors.lastname: Andersen
authors.affiliation: Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark. szehuei@gmail.com.|Current address: Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa. szehuei@gmail.com.
authors.forename: Sze Huei
authors.initials: SH
authors.lastname: Yek
authors.affiliation: Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark. DRNash@bio.ku.dk.
authors.forename: David R
authors.initials: DR
authors.lastname: Nash
authors.affiliation: Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark. JJBoomsma@bio.ku.dk.
authors.forename: Jacobus J
authors.initials: JJ
authors.lastname: Boomsma
mesh_terms: D039903:Actinobacteria / Q000254:growth & development* / Q000502:physiology; D000818:Animals; D001000:Ants / Q000382:microbiology* / Q000502:physiology; D006999:Hypocreales / Q000502:physiology*; D018515:Plant Leaves; D013559:Symbiosis