title: Transcriptome analysis reveals signature of adaptation to landscape fragmentation.
abstract: We characterize allelic and gene expression variation between populations of the Glanville fritillary butterfly (Melitaea cinxia) from two fragmented and two continuous landscapes in northern Europe. The populations exhibit significant differences in their life history traits, e.g. butterflies from fragmented landscapes have higher flight metabolic rate and dispersal rate in the field, and higher larval growth rate, than butterflies from continuous landscapes. In fragmented landscapes, local populations are small and have a high risk of local extinction, and hence the long-term persistence at the landscape level is based on frequent re-colonization of vacant habitat patches, which is predicted to select for increased dispersal rate. Using RNA-seq data and a common garden experiment, we found that a large number of genes (1,841) were differentially expressed between the landscape types. Hexamerin genes, the expression of which has previously been shown to have high heritability and which correlate strongly with larval development time in the Glanville fritillary, had higher expression in fragmented than continuous landscapes. Genes that were more highly expressed in butterflies from newly-established than old local populations within a fragmented landscape were also more highly expressed, at the landscape level, in fragmented than continuous landscapes. This result suggests that recurrent extinctions and re-colonizations in fragmented landscapes select a for specific expression profile. Genes that were significantly up-regulated following an experimental flight treatment had higher basal expression in fragmented landscapes, indicating that these butterflies are genetically primed for frequent flight. Active flight causes oxidative stress, but butterflies from fragmented landscapes were more tolerant of hypoxia. We conclude that differences in gene expression between the landscape types reflect genomic adaptations to landscape fragmentation.
authors.affiliation: Department of Biosciences, University of Helsinki, Helsinki, Finland; Institute of Biotechnology, Genome Biology Program, University of Helsinki, Helsinki, Finland.
authors.forename: Panu
authors.initials: P
authors.lastname: Somervuo
authors.affiliation: Department of Biosciences, University of Helsinki, Helsinki, Finland; Institute of Biotechnology, Genome Biology Program, University of Helsinki, Helsinki, Finland.
authors.forename: Jouni
authors.initials: J
authors.lastname: Kvist
authors.affiliation: Lammi Biological Station, University of Helsinki, Lammi, Finland.
authors.forename: Suvi
authors.initials: S
authors.lastname: Ikonen
authors.affiliation: Institute of Biotechnology, Genome Biology Program, University of Helsinki, Helsinki, Finland.
authors.forename: Petri
authors.initials: P
authors.lastname: Auvinen
authors.affiliation: Institute of Biotechnology, Genome Biology Program, University of Helsinki, Helsinki, Finland.
authors.forename: Lars
authors.initials: L
authors.lastname: Paulin
authors.affiliation: Department of Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: Patrik
authors.initials: P
authors.lastname: Koskinen
authors.affiliation: Department of Biosciences, University of Helsinki, Helsinki, Finland; Institute of Biotechnology, Genome Biology Program, University of Helsinki, Helsinki, Finland.
authors.forename: Liisa
authors.initials: L
authors.lastname: Holm
authors.affiliation: Science for Life Laboratory, Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden and Genome-Scale Biology Research Program & Institute of Biomedicine, University of Helsinki, Helsinki, Finland.
authors.forename: Minna
authors.initials: M
authors.lastname: Taipale
authors.affiliation: Department of Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: Anne
authors.initials: A
authors.lastname: Duplouy
authors.affiliation: Department of Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: Annukka
authors.initials: A
authors.lastname: Ruokolainen
authors.affiliation: Department of Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: Suvi
authors.initials: S
authors.lastname: Saarnio
authors.affiliation: Department of Biosciences, University of Helsinki, Helsinki, Finland; Department of Mathematics and Statistics, University of Helsinki, Helsinki, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Sirén
authors.affiliation: Department of Mathematics and Statistics, University of Helsinki, Helsinki, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Kohonen
authors.affiliation: Department of Mathematics and Statistics, University of Helsinki, Helsinki, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Corander
authors.affiliation: Institute of Biotechnology, Genome Biology Program, University of Helsinki, Helsinki, Finland.
authors.forename: Mikko J
authors.initials: MJ
authors.lastname: Frilander
authors.affiliation: Department of Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: Virpi
authors.initials: V
authors.lastname: Ahola
authors.affiliation: Department of Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: Ilkka
authors.initials: I
authors.lastname: Hanski
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002080:Butterflies / Q000235:genetics* / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics; D016000:Cluster Analysis; D017753:Ecosystem; D015870:Gene Expression; D020869:Gene Expression Profiling; D005787:Gene Frequency; D014644:Genetic Variation; D016678:Genome; D019476:Insect Proteins / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D015854:Up-Regulation
chemical_list: D002352:Carrier Proteins; D019476:Insect Proteins; C092382:arylphorin-binding proteins, insect