对比种间受选择位点的分布

Investigating the role of natural selection on coding sequence evolution in salmonids through NGS data mining.

Identifying DNA regions evolving under the effect of either positive or stabilizing selection, and quantifying the intensity of the selective pressures at play, represent major goals in evolutionary biology. The combination of next generation sequencing with a comparative genomics approach appears particularly promising towards yielding detailed insights into these issues. Here, we applied this strategy to investigate patterns of nucleotide substitutions in five species of the salmonid family (Salmo salar, Onchorynchus mykiss, Salvelinus fontinalis, Salvelinus namaycush, Coregonus clupeaformis) and compare this information with other fishes (Esox lucius, Danio rerio) for which genome information is available in order to infer the role of natural selection on the evolution of protein coding genes. We found evidence for positive selection across the seven fish genomes analysed. More precisely, we i) identified 707 orthologous genes and computed ratio of rates of divergence (dN/dS ratio) to identify those genes that deviated significantly from neutral expectations; ii) associated GO terms to the subset of 58 orthologs found to be under the influence of positive selection and identified 6 biological processes over-represented in this subset of positively selected orthologs, and iii) identified a subset candidates genes that have rapidly evolved under the influence of positive selection within salmonids, thus warranting further investigation in regards to their putative role in the process of adaptive divergence in salmonids.