title: Evolutionary history of host use, rather than plant phylogeny, determines gene expression in a generalist butterfly.
abstract: BACKGROUND
  Although most insect species are specialized on one or few groups of plants, there are phytophagous insects that seem to use virtually any kind of plant as food. Understanding the nature of this ability to feed on a wide repertoire of plants is crucial for the control of pest species and for the elucidation of the macroevolutionary mechanisms of speciation and diversification of insect herbivores. Here we studied Vanessa cardui, the species with the widest diet breadth among butterflies and a potential insect pest, by comparing tissue-specific transcriptomes from caterpillars that were reared on different host plants. We tested whether the similarities of gene-expression response reflect the evolutionary history of adaptation to these plants in the Vanessa and related genera, against the null hypothesis of transcriptional profiles reflecting plant phylogenetic relatedness.
  
  
  RESULTS
  Using both unsupervised and supervised methods of data analysis, we found that the tissue-specific patterns of caterpillar gene expression are better explained by the evolutionary history of adaptation of the insects to the plants than by plant phylogeny.
  
  
  CONCLUSIONS
  Our findings suggest that V. cardui may use two sets of expressed genes to achieve polyphagy, one associated with the ancestral capability to consume Rosids and Asterids, and another allowing the caterpillar to incorporate a wide range of novel host-plants.
authors.affiliation: Department of Zoology Ecology, Stockholm University, Svante Arrheniusväg 18 B, 106 91, Stockholm, Sweden. maria.celorio@zoologi.su.se.
authors.forename: Maria de la Paz
authors.initials: Mde L
authors.lastname: Celorio-Mancera
authors.affiliation: Department of Zoology Ecology, Stockholm University, Svante Arrheniusväg 18 B, 106 91, Stockholm, Sweden. chris.wheat@zoologi.su.se.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Wheat
authors.affiliation: Science for Life Laboratory, Stockholm, Sweden. mikael.huss@scilifelab.se.
authors.forename: Mikael
authors.initials: M
authors.lastname: Huss
authors.affiliation: Science for Life Laboratory, Stockholm, Sweden. francesco.vezzi@scilifelab.se.
authors.forename: Francesco
authors.initials: F
authors.lastname: Vezzi
authors.affiliation: Department of Zoology Ecology, Stockholm University, Svante Arrheniusväg 18 B, 106 91, Stockholm, Sweden. ramprasad.neethiraj@zoologi.su.se.
authors.forename: Ramprasad
authors.initials: R
authors.lastname: Neethiraj
authors.affiliation: Science for Life Laboratory, Stockholm, Sweden. johan.reimegard@scilifelab.se.
authors.forename: Johan
authors.initials: J
authors.lastname: Reimegård
authors.affiliation: Department of Zoology Ecology, Stockholm University, Svante Arrheniusväg 18 B, 106 91, Stockholm, Sweden. soren.nylin@zoologi.su.se.
authors.forename: Sören
authors.initials: S
authors.lastname: Nylin
authors.affiliation: Department of Zoology Ecology, Stockholm University, Svante Arrheniusväg 18 B, 106 91, Stockholm, Sweden. niklas.janz@zoologi.su.se.
authors.forename: Niklas
authors.initials: N
authors.lastname: Janz
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002080:Butterflies / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D060434:Herbivory; D007814:Larva / Q000502:physiology; D019684:Magnoliopsida / Q000235:genetics / Q000502:physiology; D010058:Oviposition; D010802:Phylogeny; D059467:Transcriptome