Insights into the evolution of Calanus spp. in the northern seas via de novo transcriptome sequencing

As an alternative to whole genome sequencing, transcriptomes of five species of Calanus were assembled de novo and annotated. Functional assignment of protein families based on clusters of orthologous genes COG and gene ontology GO annotations showed a conserved and analogous pattern of protein functions across different species. Phylogenetic analysis using maximum-likelihood of 191 single copy orthologs containing 4 393 protein-coding sequences across samples fully resolved evolutionary relationships among sibling species. Overall, our study contributes to the existing transcriptomic resources available for the genus Calanus and provides new insights on the evolutionary divergence among these closely related species of copepods.