Resurrection of Mesoplodon hotaula Deraniyagala 1963: A new species of beaked whale in the tropical Indo-Pacific

We present genetic and morphological evidence supporting the recognition of a previously synonymized species of Mesoplodon beaked whale in the tropical Indo-Pacific, Mesoplodon hotaula. Although the new species is closely-related to the rare ginkgo-toothed beaked whale M. ginkgodens, we show that these two lineages can be differentiated by maternally (mitochondrial DNA), biparentally (autosomal), and paternally (Y chromosome) inherited DNA sequences, as well as by morphological features. The reciprocal monophyly of the mtDNA genealogies and the largely parapatric distribution of these lineages is consistent with reproductive isolation. The new lineage is currently known from at least seven specimens: Sri Lanka (1), Gilbert Islands, Republic of Kiribati (1+), Palmyra Atoll, Northern Line Islands, U.S.A. (3), Maldives (1), and Seychelles (1). The type specimen (Sri Lanka) was described as a new species, M. hotaula, in 1963, but later synonymized with M. ginkgodens. This discovery brings the total number of Mesoplodon species to 15, making it, by far, the most speciose yet least known genus of cetaceans.Keywords: Species delimitation, Mesoplodon, Nuclear introns, Taxonomy, Y-chromosome, mtDNA, Morphology, Speciation, Beaked whal

Biogeography in the deep : hierarchical population genomic structure of two beaked whale species

Funding for this research was provided by the Office of Naval Research, Award numbers N000141613017 and N000142112712. ABO was supported by a partial studentship from the University of St Andrews, School of Biology; OEG by the Marine Alliance for Science and Technology for Scotland (Scottish Funding Council grant HR09011); ELC by a Rutherford Discovery Fellowship from the Royal Society of New Zealand Te Aparangi; NAS by a Ramon y Cajal Fellowship from the Spanish Ministry of Innovation; MLM by the European Union’s Horizon 2020 Research and Innovation Programme (Marie Skłodowska-Curie grant 801199); CR by the Marine Institute (Cetaceans on the Frontier) and the Irish Research Council; and MTO by the Hartmann Foundation.The deep sea is the largest ecosystem on Earth, yet little is known about the processes driving patterns of genetic diversity in its inhabitants. Here, we investigated the macro- and microevolutionary processes shaping genomic population structure and diversity in two poorly understood, globally distributed, deep-sea predators: Cuvier’s beaked whale (Ziphius cavirostris) and Blainville’s beaked whale (Mesoplodon densirostris). We used double-digest restriction associated DNA (ddRAD) and whole mitochondrial genome (mitogenome) sequencing to characterise genetic patterns using phylogenetic trees, cluster analysis, isolation-by-distance, genetic diversity and differentiation statistics. Single nucleotide polymorphisms (SNPs; Blainville’s n = 43 samples, SNPs=13988; Cuvier’s n = 123, SNPs= 30479) and mitogenomes (Blainville’s n = 27; Cuvier’s n = 35) revealed substantial hierarchical structure at a global scale. Both species display significant genetic structure between the Atlantic, Indo-Pacific and in Cuvier’s, the Mediterranean Sea. Within major ocean basins, clear differentiation is found between genetic clusters on the east and west sides of the North Atlantic, and some distinct patterns of structure in the Indo-Pacific and Southern Hemisphere. We infer that macroevolutionary processes shaping patterns of genetic diversity include biogeographical barriers, highlighting the importance of such barriers even to highly mobile, deep-diving taxa. The barriers likely differ between the species due to their thermal tolerances and evolutionary histories. On a microevolutionary scale, it seems likely that the balance between resident populations displaying site fidelity, and transient individuals facilitating gene flow, shapes patterns of connectivity and genetic drift in beaked whales. Based on these results, we propose management units to facilitate improved conservation measures for these elusive species.Publisher PDFPeer reviewe

Biogeography in the deep: hierarchical population genomic structure of two beaked whale species

The deep sea is the largest ecosystem on Earth, yet little is known about the processes driving patterns of genetic diversity in its inhabitants. Here, we investigated the macro- and microevolutionary processes shaping genomic population structure and diversity in two poorly understood, globally distributed, deep-sea predators: Cuvier’s beaked whale (Ziphius cavirostris) and Blainville’s beaked whale (Mesoplodon densirostris). We used double-digest restriction associated DNA (ddRAD) and whole mitochondrial genome (mitogenome) sequencing to characterise genetic patterns using phylogenetic trees, cluster analysis, isolation-by-distance, genetic diversity and differentiation statistics. Single nucleotide polymorphisms (SNPs; Blainville’s n=43 samples, SNPs=13988; Cuvier’s n=123, SNPs= 30479) and mitogenomes (Blainville’s n=27; Cuvier’s n=35) revealed substantial hierarchical structure at a global scale. Both species display significant genetic structure between the Atlantic, Indo-Pacific and in Cuvier’s, the Mediterranean Sea. Within major ocean basins, clear differentiation is found between genetic clusters on the east and west sides of the North Atlantic, and some distinct patterns of structure in the Indo-Pacific and Southern Hemisphere. We infer that macroevolutionary processes shaping patterns of genetic diversity include biogeographical barriers, highlighting the importance of such barriers even to highly mobile, deep-diving taxa. The barriers likely differ between the species due to their thermal tolerances and evolutionary histories. On a microevolutionary scale, it seems likely that the balance between resident populations displaying site fidelity, and transient individuals facilitating gene flow, shapes patterns of connectivity and genetic drift. Based on these results, we propose management units to facilitate improved conservation measures for these elusive species

Cetacean records from Tristan da Cunha, South Atlantic

The cetacean fauna at the Tristan da Cunha archipelago has been assessed from ship-based, aerial and land-based observations from 1983–2000, from strandings on Tristan da Cunha and Inaccessible Island between 1983 and 1995, and from whaling catch data from 1934–1967. Five species (Eubalaena australis, Megaptera novaeangliae, Tasmacetus shepherdi, Globicephala melas and Orcinus orca) have been sighted within the territorial waters of the archipelago, eight species (Balaenoptera physalus, B. borealis, B. acutorostrata/bonaerensis, Physeter macrocephalus, Mesoplodon mirus, M. bowdoini, Delphinus sp. and Lissodelphis peronii) have been seen or taken within 200 nautical miles (360 km) of the group or have been found stranded on its shores, while another two species (Caperea marginata and Lagenorhynchus obscurus) have been recorded close enough to be considered likely to occur within 200 nautical miles. The records of Mesoplodon mirus and M. bowdoini represent significant extensions to their known distribution. Apart from its possible importance as a mid-oceanic nursery area for southern right whales, the waters of the Tristan Archipelago seem to be a concentration area for T. shepherdi, one of the least-known of the world’s cetaceans

Estimating the number of whales entering trade using DNA profiling and capture-recapture analysis of market products

Surveys of commercial markets combined with molecular taxonomy (i.e. molecular monitoring) provide a means to detect products from illegal, unregulated and/or unreported (IUU) exploitation, including the sale of fisheries bycatch and wild meat (bushmeat). Capture-recapture analyses of market products using DNA profiling have the potential to estimate the total number of individuals entering the market. However, these analyses are not directly analogous to those of living individuals because a ‘market individual’ does not die suddenly but, instead, remains available for a time in decreasing quantities, rather like the exponential decay of a radioactive isotope. Here we use mitochondrial DNA (mtDNA) sequences and microsatellite genotypes to individually identify products from North Pacific minke whales (Balaenoptera acutorostrata ssp.) purchased in 12 surveys of markets in the Republic of (South) Korea from 1999 to 2003. By applying a novel capture-recapture model with a decay rate parameter to the 205 unique DNA profiles found among 289 products, we estimated that the total number of whales entering trade across the five-year survey period was 827 (SE, 164; CV, 0.20) and that the average ‘half-life’ of products from an individual whale on the market was 1.82 months (SE, 0.24; CV, 0.13). Our estimate of whales in trade (reflecting the true numbers killed) was significantly greater than the officially reported bycatch of 458 whales for this period. This unregulated exploitation has serious implications for the survival of this genetically distinct coastal population. Although our capture-recapture model was developed for specific application to the Korean whale-meat markets, the exponential decay function could be modified to improve the estimates of trade in other wildmeat or fisheries markets or abundance of living populations by noninvasive genotyping

Contamination level of mercury in red meat products from cetaceans available from South Korea markets

Levels of total mercury (T-Hg) were surveyed in red meat (n = 73) and liver (n = 3) from toothed whales, dolphins and porpoises (odontocetes) sold for human consumption in the coastal cities of South Korea. High concentrations of T-Hg were found in the liver products of finless porpoises (18.7 and 156 μg/wet g) and common dolphins (13.2 μg/wet g). The T-Hg concentrations in red meat products were highest in the false killer whale (9.66 ± 12.3 μg/wet g, n = 9), bottlenose dolphin (10.6 ± 12.6 μg/wet g, n = 3) and killer whale (13.3 μg/wet g, n = 1), and lowest in Cuvier’s beaked whale and the harbour porpoise (0.4–0.5 μg/wet g). Thus, most of the products that originated from odontocetes exceeded the safety limit of 0.5 μg/wet g for T-Hg set by the South Korean health authorities for the fishery industry. Pregnant women and other vulnerable sectors of the population living in South Korea should therefore limit their consumption of odontocete products

Cetacean records from Tristan da Cunha, South Atlantic

The cetacean fauna at the Tristan da Cunha archipelago has been assessed from ship-based, aerial and land-based observations from 1983–2000, from strandings on Tristan da Cunha and Inaccessible Island between 1983 and 1995, and from whaling catch data from 1934–1967. Five species (Eubalaena australis, Megaptera novaeangliae, Tasmacetus shepherdi, Globicephala melas and Orcinus orca) have been sighted within the territorial waters of the archipelago, eight species (Balaenoptera physalus, B. borealis, B. acutorostrata/bonaerensis, Physeter macrocephalus, Mesoplodon mirus, M. bowdoini, Delphinus sp. and Lissodelphis peronii) have been seen or taken within 200 nautical miles (360 km) of the group or have been found stranded on its shores, while another two species (Caperea marginata and Lagenorhynchus obscurus) have been recorded close enough to be considered likely to occur within 200 nautical miles. The records of Mesoplodon mirus and M. bowdoini represent significant extensions to their known distribution. Apart from its possible importance as a mid-oceanic nursery area for southern right whales, the waters of the Tristan Archipelago seem to be a concentration area for T. shepherdi, one of the least-known of the world’s cetaceans