UC San Diego

Mitochondrial genomes (mitogenomes) code for, in part, the enzymes involved in the creation of energy for cellular function. Altering these highly conserved genes even slightly can have a biochemical impact on this pathway. Analyzing the mitogenome for positive selection using models that take biochemically significant changes into account can identify adaptive alterations presumably under selection due to energetic costs that vary across lineages due to physiological divergence, environmental factors, or ecological drivers. This study was conducted on the mitochondrial cytochrome B (CYTB) gene of 45 cetacean species. Using TreeSAAP, I identified evidence of positive selection based on five physicochemical properties acting on several of the transmembrane helical regions of CYTB. In addition to these broad regional findings, 88 codon sites were identified to have undergone radical and significant changes. Further computational analysis will be necessary in order to better resolve which codons are undergoing adaptive changes. This study was not able to conclusively identify any singular metabolic driver for amino acid alterations among lineages