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.