Filogeografia da baleia-bicuda-de-Cuvier, Ziphius cavirostris (Odontoce-ti: Ziphiidae)

Abstract

Cuvier's beaked whale, Ziphius cavirostris, is the best known and most studied Ziphiidae species, mainly due to its extensive distribution. The species is known as the cetacean that dives to greatest depths for the longest time, and for mass strand-ings associated with exposure to military exercises and medium-frequency sonar. Most studies involve understanding the mechanisms behind this behavior and the anthropogenic impacts on the species. There is still little information about its genetic diversity. Available information is conflicting and suggests new studies to confirm the hypotheses raised. In Brazil, despite the significant number of strandings, the studies carried out are limited to stranding reports. No population analysis was performed and there is no data on regional diversity of the species. The present study obtained the first sequences of the mitochondrial DNA control region for the species in Brazil and performs the most comprehensive population analysis to date, including new and previously published sequences from the North Atlantic, North Pacific and Indo-Pacific regions. The new Brazilian sequences, despite being geographically closer to the North Atlantic, share the haplotype that is most frequently found in the Southern Hemisphere. Contrary to what was previously observed, greatest genetic diversity occurs within ocean basins (55,35 %; FST = 0,44648) and no haplotype groups were observed in the phylogenetic reconstructions. Although pairwise analyzes indicate a significant differentiation between ocean basins, sequences available for the South Atlantic and Indian Oceans are still limited and do not allow us to reach further con-clusions regarding the species population structure.