Complete mitochondrial genomes and phylogeny of two rare whale species: True’s (Mesoplodon mirus: True 1913) and Sowerby’s (Mesoplodon bidens: Sowerby 1804) beaked whales

Abstract

Beaked whales of the genus Mesoplodon are rarely encountered and information on their basic biology is lacking. We sequenced the complete mitochondrial genomes of True's (Mesoplodon mirus) and Sowerby's (Mesoplodon bidens) beaked whales to high depth (>120X). The length of the de novo assembled genomes was 16,342 bp (M. mirus) and 16,347 bp (M. bidens), with GC compositions of 37.7 and 39.2%, respectively. A maximum-likelihood phylogeny supports the hypotheses that M. mirus is most closely related to Mesoplodon europaeus, and that M. bidens is the basal species of the genus. These data provide molecular resources that will aid in further understanding population genetics and evolution in this rare and poorly understood group of cetaceans. ARTICLE HISTORY

Specimens of opportunity provide vital information for research and conservation regarding elusive whale species

“…Little genetic information is available for this species. Mitochondrial and nuclear analyses suggest the Sowerby's beaked whale may be the most basal member of the genus (Einfeldt et al 2019b, Mcgowen et al 2019. Regionally distinct and overlapping mitochondrial haplotypes were identified in east and west Atlantic specimens (n = 7 and 7, respectively); however, the results of this analysis were never published (COSEWIC 2006).…”

“…Genetic analyses of museum specimens identified four new species of beaked whales in the last 20 years, and three species of beaked whales -Mesoplodon bowdoini, M. traversii and M. hotaulaare known only from morphological and genetic analyses of stranded specimens (Dalebout et al 2002, Dalebout et al 2014, Morin et al 2017, Yamada et al 2019. Phylogenies have been generated using specimens of opportunity, resolving questions of relatedness among certain species (Dalebout et al 2008, Einfeldt et al 2019b; comparative anatomy of beach-cast carcasses has helped to identify species-specific morphological differences (Mead 2007, Lambert et al 2011, March et al 2016; and necropsies have shed light on beaked whale parasites and diseases, sexual maturity and gestation times (Besharse 1971, Auriolesgamboa 1992, Macleod & Herman 2004, Landrau-Giovannetti et al 2020.…”

A review of beaked whale (Ziphiidae) stranding incidents from the inshore waters of eastern Canada

“…Although encountered far from their natural habitat when stranded, beached ziphiids remain an important source of information for both natural history and conservation. For example, Einfeldt et al (2019a) sequenced the complete mitochondrial genome for True's Beaked Whale (Mesoplodon mirus) from tissue taken from an animal stranded on Iles de la Madeleine, Quebec (QC), while Desforges et al (2021) was able to undertake full-depth blubber analysis for contaminants from a Northern Bottlenose Whale (Hyperoodon ampulla tus) stranded in Newfoundland (NF). With the exception of the Northern Bottlenose Whale population that occupies the Scotian Shelf (Whitehead and Hooker 2012), the distributions of ziphiids that occur off Canada's east coast are not well understood.…”