2.2 Positive Selection
To identify genes in the blue whale, the largest mammal, that are positively selected and associated with longevity or reduced cancer rates, we compared genomes of the blue whale with one of the smallest baleen whales, the minke whale (Balaenoptera acutorostrata, Yim et al., 2014). The NA blue whale and the minke whale transcripts were filtered and translated. The single gene orthologs (SGOs) were identified between blue and minke whales with reciprocal best hits using VESPA (Webb et al., 2017), BLASTp and MUSCLE (Edgar, 2004). Positive selection was analyzed using pairwise comparison with KAKS_CALCULATOR v2.0 (Wang, Zhang, Zhang, Zhu, & Yu, 2010) between NA blue whale transcript and minke whale (downloaded from NCBI: GCF_000493695.1_BalAcu1.0). Tajima’s D (Sabeti et al., 2006) analysis was used to screen for regions under positive selection for the 12 present-day NA blue whales (Supplemental Information). The paired-end Illumina reads from the 12 whales were aligned to masked autosomal genome of the NA blue whale and the SNPs detected were analyzed as described in the Supplemental Information.