The Origin and Genetic Relationships of the Baikal Seal, Phoca sibirica, by Restriction Analysis of Mitochondrial DNA

Sasaki, Hiroyuki; Numachi, Ken-ichi; Грачев, М.А.

doi:10.2108/zsj.20.1417

Cited by 21 publications

(23 citation statements)

References 9 publications

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“…Several recent studies have employed molecular dating techniques to address aspects of phocid biogeography and divergence times using mitochondrial (mt) restriction fragment length polymorphisms (RFLPs; Sasaki et al. , 2003), mtDNA (Árnason et al.…”

Section: Introductionmentioning

confidence: 99%

Multiple fossil calibrations, nuclear loci and mitochondrial genomes provide new insight into biogeography and divergence timing for true seals (Phocidae, Pinnipedia)

Fulton

Strobeck

2010

Journal of Biogeography

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Aim To better understand the historical biogeography of the true seals, Phocidae, by combining nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) in a divergence time analysis using multiple fossil calibrations.Location Arctic, Antarctic, Pacific and Atlantic Oceans, Lake Baikal, Caspian Sea.Methods Fifteen nuclear genes totalling 8935 bp plus near-complete mitochondrial genome sequences were used in a Bayesian divergence time analysis, incorporating eight soft-bound fossil calibrations across the phylogeny. All species of true seals were included, plus the walrus, three otariids and seven carnivore outgroups. The majority of the nuclear sequences and four phocid mitochondrial genomes (plus three non-phocid mitochondrial genomes) were newly generated for this study using DNA extracted from tissue samples; other sequences were obtained from GenBank.Results Using multiple nuclear genes and multiple fossil calibrations resulted in most divergence time estimations within Phocidae being much more recent than predicted by other molecular studies incorporating only mtDNA and using a single calibration point. A new phylogenetic hypothesis was recovered for the Antarctic seals.Main conclusions Incorporating multiple nuclear genes and fossil calibrations had a profound effect on the estimated divergence times. Most estimated divergences within Phocinae (Arctic seals) correspond to Arctic oceanic events and all occur within the last 12 Myr, a time when the Arctic and Atlantic oceans were freely exchanging and perennial Arctic sea ice existed, indicating that the Arctic seals may have had a longer association with ice than previously thought. The Monachinae ('southern' seals) split from the Phocinae c. 15 Ma on the eastern US coast. Several early trans-Atlantic dispersals possibly occurred, leaving no living descendants, as divergence estimates suggest that the Monachus (monk seal) species divergences occurred in the western Atlantic c. 6 Ma, with the Mediterranean monk seal ancestor dispersing afterwards. The tribes Lobodontini (Antarctic seals) and Miroungini (elephant seals) are also estimated to have diverged in the eastern Atlantic c. 7 Ma and a single Lobodontini dispersal to Antarctica occurred shortly afterwards. Many of the newly estimated dates are used to infer how extinct lineages/taxa are allied with their living relatives.

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Section: Introductionmentioning

confidence: 99%

Multiple fossil calibrations, nuclear loci and mitochondrial genomes provide new insight into biogeography and divergence timing for true seals (Phocidae, Pinnipedia)

Fulton

Strobeck

2010

Journal of Biogeography

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“…Difficulty in resolving Phocina relationships is complicated not only by rapid radiation, but also by extremely large population sizes: the ringed seal exists in extremely high numbers (N 5-7 million) in a largely panmictic population (King 1983;Palo et al 2001;Sasaki et al 2003), suggesting large effective population size. Phocina species radiated approximately 1.4-2.6 Ma (Fulton & Strobeck in press), and with generation times of approximately 11-17 years, it is possible that sufficient effective generations have not passed for complete lineage sorting.…”

Section: Introductionmentioning

confidence: 99%

Multiple markers and multiple individuals refine true seal phylogeny and bring molecules and morphology back in line

Fulton

Strobeck

2009

Proc. R. Soc. B.

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Despite decades of study, some aspects of Phocidae (Pinnipedia, Carnivora) phylogeny still remain unresolved. Using the largest novel dataset to date, including all extant phocids and comprising 15 nuclear and 13 mitochondrial genes, we illustrate the utility of including multiple individuals per species in resolving rapid radiations, and provide new insight into phocid phylogeny. In line with longstanding morphological views, Pusa is recovered as monophyletic for the first time with genetic data. The data are also used to explore the relationship between genetic distance and taxonomic rank. Intraspecific sampling also highlights the discrepancy between molecular and morphological rates of evolution within Phocidae.

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“…The top predator, and the only endemic mammal of the lake, is the Baikal seal Phoca sibirica. A recent study of its mitochondrial DNA suggests that its ancestor reached Lake Baikal approximately 0.4 million yr ago, apparently through the Yenisei-Angara waterway (Sasaki et al 2003), and that it is much more closely related to the ringed seal P. hispida than to the Caspian seal P. caspica. In 2000 the population was calculated at 75 800 seals of ≥1 yr of age (Petrov 2000).…”

Section: Introductionmentioning

confidence: 99%

Fatty acid composition of blubber of the Baikal seal Phoca sibirica and its marine relative, the ringed seal P. hispida

Grahl‐Nielsen

Halvorsen²,

Bodoev³

et al. 2005

Mar. Ecol. Prog. Ser.

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The fatty acid (FA) composition was determined in the blubber of 5 adult Baikal seals Phoca sibirica caught in July 2001, nine 1-mo old pups caught in April 2002, and 25 adults and fetuses from 3 of these, caught in October 2002, all along the SE shores of Lake Baikal, eastern Siberia. For comparison, FA in the blubber of ringed seals P. hispida, the closest marine relative of the Baikal seal, caught along the ice edge around Svalbard during 1999 and 2000 were also analyzed. The FA of the main prey of the Baikal and ringed seals, the endemic golomyanka Comephorus baikalensis and polar cod Boreogadus saida, respectively, were also studied. The same suite of FA was found in all samples. Saturated FA (SFA) with branched chains, all n6 polyunsaturated FA (PUFA) and 18:3n3 and 20:3n3 were more abundant in the blubber of the Lake Baikal seal and in the golomyanka than in the blubber of the marine ringed seal and marine fishes. In contrast, the relative levels of monounsaturated FAs (MUFA) with 20 and 22 carbons and polyunsaturated 20:5n3 were lower in the Baikal species than in the Svalbard species. The FA composition of the inner blubber was significantly different from the FA composition of the outer blubber in both species. Despite large differences in FA composition between Baikal and ringed seal blubbers, vertical differences were manifested in the same FA: MUFA with 14, 16 and 18 carbons were present in higher relative abundance in the outer than in the inner layer. In both species all the other quantitatively important FA had lower or equal relative values in the outer layer. The FA composition of the seals' blubber differed from that of their main prey. The difference was, however, smaller between prey and inner blubber than between prey and outer blubber. The FA composition of the inner blubber of adults showed temporal differences. Since the change from prey to blubber in relative concentration occurred in the same direction for all but 5 FA, the selection of FA during deposition in the inner blubber was similar for the 2 species, even though there was a large difference between the general FA composition of the freshwater and marine lipids. The FA composition in the blubber of adults, pups and fetuses differed.

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The Origin and Genetic Relationships of the Baikal Seal, Phoca sibirica, by Restriction Analysis of Mitochondrial DNA

Cited by 21 publications

References 9 publications

Multiple fossil calibrations, nuclear loci and mitochondrial genomes provide new insight into biogeography and divergence timing for true seals (Phocidae, Pinnipedia)

Multiple fossil calibrations, nuclear loci and mitochondrial genomes provide new insight into biogeography and divergence timing for true seals (Phocidae, Pinnipedia)

Multiple markers and multiple individuals refine true seal phylogeny and bring molecules and morphology back in line

Fatty acid composition of blubber of the Baikal seal Phoca sibirica and its marine relative, the ringed seal P. hispida

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