Environmental adaptation in an alpine ground beetle

<p>We test for evidence of adaptive evolution in the alpine ground beetle <em>Nebria</em> <em>vandykei</em>. First, we explore the genetic pathways induced during environmental stress responses through RNA sequencing, showing that cold, heat and desiccation stress activate a largely non-overlapping set of molecular pathways. Using additional transcriptome sequencing, we estimate the evolutionary relationship of <em>N. vandykei</em> to related species in the subgenus Catonebria and several outgroups. Phylogenetic analyses suggest a history of admixture or very rapid diversification underlies the evolution of <em>N. vandykei</em>. Finally, using tests for positive selection polarized by high and low elevation relatives, we demonstrate selection acting on stress response pathways, as well as pathways known to function in tolerance to cold and hypoxic environments. </p>