COMPARATIVE GENOMICS AND TRANSCRIPTOMICS TO HIGHLIGHT THE EVOLUTION OF HEMOGLOBIN SUBUNIT ALPHA WITHIN PACIFIC ROCKFISHES (SEBASTES SPP.)

Oceanic profiles are well studied and cataloged for dissolved oxygen, temperature, light and salinity-below the euphotic zone there is a decrease in availability of many of these abiotic factors. Rockfishes (Sebastes spp.) are a diverse group of marine fishes that occupy different depths of the ocean and demonstrate adaptive radiation that allows them to survive under these different factors; which makes this group of fishes a model species for studying evolutionary processes in marine systems. This is a comparative genomics and transcriptomics study that focuses on a candidate gene for hemoglobin subunit alpha (hba), which has been previously studied to better understand sensitivity to abiotic factors and has been shown to have positive Darwinian selection in rockfishes. The published and publicly available genomes of several rockfish species were used to find orthologous genes, amino acid replacements and estimate Darwinian selection across hba genes. Using brain tissue, transcriptomic datasets were analyzed for presence of hemoglobin subunit alpha loci associated with depth and the patterns of evolution of these loci. Eight sites were found under selection when analyzing selection of hba in the genomes of six species of Sebastes, while two sites were found under selection within the transcriptome of 15 species. One site, in particular, site 117, has been found under selection in different taxa that occupy extreme environments such as the bar-headed goose. This site should be considered in future studies when looking at HBA in more taxa that occupy these environments to better understand the role of HBA in adaptive evolution.