DOI: 10.5061/dryad.v41ns1rs0
title: Multiple genetic trajectories to extreme abiotic stress adaptation in Arctic Brassicaceae

description: Extreme environments offer powerful opportunities to study how different
 organisms have adapted to similar selection pressures at the molecular
 level. The Arctic is one of the most hostile environments on Earth, and
 the few plant species inhabiting this region typically possess suites of
 similar morphological and physiological adaptations to extremes in light
 and temperature. Here we compare patterns of molecular evolution in three
 Brassicaceae species that have independently colonized the Arctic, and
 present some of the first genetic evidence for plant adaptations to the
 Arctic environment. By testing for positive selection and identifying
 convergent substitutions in orthologous gene alignments for a total of 15
 Brassicaceae species, we find that positive selection has been acting on
 different genes, but similar functional pathways in the three Arctic
 lineages. The positively selected gene sets identified in the three Arctic
 species showed convergent functional profiles associated with extreme
 abiotic stress characteristic of the Arctic. However, there was little
 evidence for independently fixed mutations at the same sites and for
 positive selection acting on the same genes. The three species appear to
 have evolved similar suites of adaptations by modifying different
 components in similar stress response pathways, implying that there could
 be many genetic trajectories for adaptation to the Arctic environment. By
 identifying candidate genes and functional pathways potentially involved
 in Arctic adaptation, our results provide a framework for future studies
 aimed at testing for the existence of a functional syndrome of Arctic
 adaptation in the Brassicaceae and perhaps flowering plants in
 general. 
description: These are the Arctic <em>de novo</em> transcriptome
 assemblies made for the study (based on leaf tissue). The
 transcriptomes have been assembled with Trinity v.2.4.0, and then filtered
 so that only the highest expressed isoforms are retained. Coding regions
 have been predicted with TransDecoder v.3.0.0. For detailed material and
 methods, see the published paper. 
description: Sample details:
 CbA_topISO_121218_SHORT.FILTERED.cds/CbA_topISO_121218_SHORT.FILTERED.pep.fasta; <em>Cardamine bellidifolia</em> from Alaska/Yukon (border) (cds file/peptide file) CbS_topISO_121218_SHORT.FILTERED.cds/CbS_topISO_121218_SHORT.FILTERED.pep.fasta; <em>Cardamine bellidifolia</em> from Svalbard (cds file/peptide file) CgA_topISO_121218_SHORT.FILTERED.cds/CgA_topISO_121218_SHORT.FILTERED.pep.fasta; <em>Cochlearia groenlandica</em> from Alaska (cds file/peptide file) CgS_topISO_121218_SHORT.FILTERED.cds/CgS_topISO_121218_SHORT.FILTERED.pep.fasta; <em>Cochelaria groenlandica</em> from Svalbard (cds file/peptide file) DnA_topISO_121218_SHORT.FILTERED.cds/DnA_topISO_121218_SHORT.FILTERED.pep.fasta; <em>Draba nivalis</em> from Alaska (cds file/peptide file) DnN_topISO_121218_SHORT.FILTERED.cds/DnN_topISO_121218_SHORT.FILTERED.pep.fasta; <em>Draba nivalis</em> from mainland Norway (cds file/peptide file)