New genetic evidences for distinct populations of the common minke whale (Balaenoptera acutorostrata) in the Southern Hemisphere

Two minke whale species are recognized, the Antarctic minke (Balaenoptera bonaerensis) and the cosmopolitan common minke (Balaenoptera acutorostrata) whales. The latter is divided into three subspecies: North Pacific (NP) B. a. scammoni, North Atlantic (NA) B. a. acutorostrata, and the Southern Hemisphere ‘dwarf’ minke whales B. a. unnamed subsp. Genetic variation of two populations of dwarf common minke whales from the Western South Atlantic (WSA) and Western South Pacific (WSP) was assessed through analysis of mitochondrial DNA (mtDNA) control region sequences (313 bp) and microsatellite DNA (msDNA) (11 loci). For comparative purposes, the mtDNA analysis involved samples of Antarctic minke whales, NP, and NA common minke whales. The msDNA analysis included individuals from the WSA, WSP, and NP. There was no shared mtDNA haplotype among common minke whales, and the mtDNA haplotype phylogeny analyses placed WSA in a different cluster from WSP and closer or within the NA clade. The WSA population exhibited the lowest estimates of diversity for both markers. The estimate of Nei’s net nucleotide substitution (dA) between WSA and WSP (0.027) was larger than between WSA and NA (0.014) whales. Significant msDNA differences (based on FST and DSW) were found among NP, WSA and WSP, and the pattern of differentiation was similar to that of the mtDNA. Results suggested that the taxonomical status of common minke whales in the Southern Hemisphere should be revised and that regardless of their taxonomical status, dwarf common minke whales from WSA and WSP are unique populations that require separate management for conservation.