The Ladoga seal (Phoca hispida ladogensis Nordq.)

Island populations are on average smaller, genetically less diverse, and at a higher risk to go extinct than mainland populations. Low genetic diversity may elevate extinction probability, but the genetic component of the risk can be affected by the mode of diversity loss, which, in turn, is connected to the demographic history of the population. Here, we examined the history of genetic erosion in three Fennoscandian ringed seal subspecies, of which one inhabits the Baltic Sea ‘mainland’ and two the ‘aquatic islands’ composed of Lake Saimaa in Finland and Lake Ladoga in Russia. Both lakes were colonized by marine seals after their formation c. 9500 years ago, but Lake Ladoga is larger and more contiguous than Lake Saimaa. All three populations suffered dramatic declines during the 20th century, but the bottleneck was particularly severe in Lake Saimaa. Data from 17 microsatellite loci and mitochondrial control-region sequences show that Saimaa ringed seals have lost most of the genetic diversity present in their Baltic ancestors, while the Ladoga population has experienced only minor reductions. Using Approximate Bayesian computing analyses, we show that the genetic uniformity of the Saimaa subspecies derives from an extended founder event and subsequent slow erosion, rather than from the recent bottleneck. This suggests that the population has persisted for nearly 10,000 years despite having low genetic variation. The relatively high diversity of the Ladoga population appears to result from a high number of initial colonizers and a high post-colonization population size, but possibly also by a shorter isolation period and/or occasional gene flow from the Baltic Sea.

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“…) were set based on published estimates (Sipilä et al. ; Sipilä ; Sundqvist et al. ; Metsähallitus Natural Heritage Services ; Trukhanova et al.…”

Section: Methodsmentioning

confidence: 99%

“…During their extended isolation, these populations have evolved into distinct subspecies that are morphologically, behaviorally, and genetically differentiated from each other, as well as from the direct descendants of their Yoldian ancestors in the current Baltic Sea ( P. h. botnica ) (Sipilä et al. ; Hyvärinen et al. ; Amano et al.…”

Section: Introductionmentioning

confidence: 99%

Demographic histories and genetic diversities of Fennoscandian marine and landlocked ringed seal subspecies

Nyman

Valtonen

Aspi

et al. 2014

Ecology and Evolution

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“…There is plenty of evidence (Sipilä, 1996;Kunnasranta, 2001;Agafonova, 2007) that the Ladoga seals prefer to give birth in fast ice zone, on the border between the primary and secondary ice with lots of hummocks and ridges. In northern areas of the lake the lairs are generally formed in showdrifts on the shorelines of islands and islets.…”

Section: Discussionmentioning

confidence: 99%

The Ladoga ringed seal (Pusa hispida ladogensis) under changing climatic conditions

Trukhanova¹

2013

Rus.J.Theriol.

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“…According to Soderberg (1975), the daily need of the Baltic ringed seal for fish (based on an average body weight) is estimated to be about 3.5 kg. The Baltic ringed seal is the largest of the subspecies (mean weight about 90 kg, Helle 1979) and the daily food intake in the smaller Saimaa ringed seal (mean weight about 60 kg, Sipila et al 1996) must be lower. The results from our study of the captive Saimaa ringed seal showed that the mean consumption of offered fish per day was 2.2 kg (about 800 kg annually).…”

Section: Discussionmentioning

confidence: 99%

The diet of the Saimaa ringed seal Phoca hispida saimensis

Kunnasranta¹,

Hyvärinen²,

Sipilä³

et al. 1999

Acta Theriol.

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. 1999. The diet of the Saimaa ringed seal Phoca hispida saimensis. Acta Theriologica 44: 443-450.The diet of the Saimaa ringed seal Phoca hispida saimensis Nordquist, 1899 was studied by the analysis of stomach contents and by feeding trials with a captive seal. Nine prey species were found in the stomachs, the most important being small schooling fish species: perch Perca fluviatilis, roach Rutilus rutilus, vendace Coregonus albula, smelt Osmerus eperlanus and ruff Acerina cernua. The importance of crustaceans in the diet of the ringed seal in Lake Saimaa is insignificant. Length of the intestinal tract of the Saimaa ringed seal is relatively shorter than those of marine ringed seals. In cafeteria tests on one captive seal the preferred fish species were vendace and smelt. The captive seal displayed clear seasonal variation in feeding activity. The consumption of fish was lowest in springtime and highest in autumn and winter.

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The Ladoga seal (Phoca hispida ladogensis Nordq.)

Cited by 12 publications

References 3 publications

Demographic histories and genetic diversities of Fennoscandian marine and landlocked ringed seal subspecies

Demographic histories and genetic diversities of Fennoscandian marine and landlocked ringed seal subspecies

The Ladoga ringed seal (Pusa hispida ladogensis) under changing climatic conditions

The diet of the Saimaa ringed seal Phoca hispida saimensis

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