title: Comparative transcriptomics reveals the conserved building blocks involved in parallel evolution of diverse phenotypic traits in ants.
abstract: BACKGROUND
  Reproductive division of labor in eusocial insects is a striking example of a shared genetic background giving rise to alternative phenotypes, namely queen and worker castes. Queen and worker phenotypes play major roles in the evolution of eusocial insects. Their behavior, morphology and physiology underpin many ecologically relevant colony-level traits, which evolved in parallel in multiple species.
  
  
  RESULTS
  Using queen and worker transcriptomic data from 16 ant species we tested the hypothesis that conserved sets of genes are involved in ant reproductive division of labor. We further hypothesized that such sets of genes should also be involved in the parallel evolution of other key traits. We applied weighted gene co-expression network analysis, which clusters co-expressed genes into modules, whose expression levels can be summarized by their 'eigengenes'. Eigengenes of most modules were correlated with phenotypic differentiation between queens and workers. Furthermore, eigengenes of some modules were correlated with repeated evolution of key phenotypes such as complete worker sterility, the number of queens per colony, and even invasiveness. Finally, connectivity and expression levels of genes within the co-expressed network were strongly associated with the strength of selection. Although caste-associated sets of genes evolve faster than non-caste-associated, we found no evidence for queen- or worker-associated co-expressed genes evolving faster than one another.
  
  
  CONCLUSIONS
  These results identify conserved functionally important genomic units that likely serve as building blocks of phenotypic innovation, and allow the remarkable breadth of parallel evolution seen in ants, and possibly other eusocial insects as well.
authors.affiliation: Centre of Excellence in Biological Interactions, Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland. claire.morandin@helsinki.fi.|Tvärminne Zoological Station, University of Helsinki, J.A. Palménin tie 260, FI-10900, Hanko, Finland. claire.morandin@helsinki.fi.
authors.forename: Claire
authors.initials: C
authors.lastname: Morandin
authors.affiliation: Okinawa Institute of Science and Technology, 1919-1 Tancha Onna-son, Kunigami-gun, Okinawa, 904-0412, Japan.
authors.forename: Mandy M Y
authors.initials: MM
authors.lastname: Tin
authors.affiliation: Department of Environmental Sciences, University of Girona, Campus Montilivi, 17071, Girona, Spain.
authors.forename: Sílvia
authors.initials: S
authors.lastname: Abril
authors.affiliation: Department of Environmental Sciences, University of Girona, Campus Montilivi, 17071, Girona, Spain.
authors.forename: Crisanto
authors.initials: C
authors.lastname: Gómez
authors.affiliation: Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100, Copenhagen, Denmark.
authors.forename: Luigi
authors.initials: L
authors.lastname: Pontieri
authors.affiliation: Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100, Copenhagen, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Schiøtt
authors.affiliation: Centre of Excellence in Biological Interactions, Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.|Tvärminne Zoological Station, University of Helsinki, J.A. Palménin tie 260, FI-10900, Hanko, Finland.
authors.forename: Liselotte
authors.initials: L
authors.lastname: Sundström
authors.affiliation: Department of Subtropical Agro-Environmental Sciences, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa, 903-0213, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Tsuji
authors.affiliation: Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100, Copenhagen, Denmark.
authors.forename: Jes Søe
authors.initials: JS
authors.lastname: Pedersen
authors.affiliation: Centre of Excellence in Biological Interactions, Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.|Tvärminne Zoological Station, University of Helsinki, J.A. Palménin tie 260, FI-10900, Hanko, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Helanterä
authors.affiliation: Okinawa Institute of Science and Technology, 1919-1 Tancha Onna-son, Kunigami-gun, Okinawa, 904-0412, Japan. sasha@homologo.us.|Research School of Biology, Australian National University, Canberra, ACT, 0200, Australia. sasha@homologo.us.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Mikheyev
mesh_terms: D000818:Animals; D001000:Ants / Q000235:genetics*; D001522:Behavior, Animal; D019143:Evolution, Molecular; D010641:Phenotype; D012098:Reproduction; D059467:Transcriptome / Q000235:genetics*