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Papers by Tanya Sitnikova
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2000
In Lake Baikal, extremely thin shells are reported as a typical feature of endemic gastropods. Th... more In Lake Baikal, extremely thin shells are reported as a typical feature of endemic gastropods. This statement derived only from observations; no experimental data were available up to now. Therefore, we quantitatively investigated the calcium distribution in the endemic prosobranch gastropod Benedictia baicalensis and compared the results with those of Lithoglyphus naticoides, a near relative, non-endemic, palaearctic species. The shell of the endemic mollusc B. baicalensis consists of 94.9 926.0 mg Ca 2 + /ml animal volume (n=43), and in L. naticoides 865.09 271.5 mg Ca 2 + /ml (n= 10). Calcium contents in the tissue of B. baicalensis vary between different sampling stations and different sampling dates (from 9.49 5.1 (n= 33) to 20.59 8.4 mg Ca 2 + /mg dry weight DW (n =16)) and are only 1/5-1/10 compared to L. naticoides (88.5 939.1 mg Ca 2 + /mg DW (n=9)). But the values for hemolymph calcium concentration and osmolality in both species are identical (B. baicalensis: osmolality: 84.4 95.3 mosm/kg (n= 40); hemolymph calcium concentration: 4.691.7 mmol/l (n=40). L. naticoides: osmolality: 85.0 9 2.0 mosm/kg (n=8); hemolymph calcium concentration: 5.2 95.0 mmol/l (n=40).). This is the first experimental study demonstrating, that-besides a similar hemolymph ionic composition-the Baikalian species is characterized by significantly lower calcium storage in shell and tissue than the nearly related non-endemic species.
A new species of the family Planorbidae is described from the land thermal spring Khakusy, on the... more A new species of the family Planorbidae is described from the land thermal spring Khakusy, on the northeastern shore of Lake Baikal. The description of Gyraulus takhteevi sp. n. includes morphological characters and gene sequences (COI of mtDNA) for the species separation from sister taxon Gyraulus acronicus (A. Férussac, 1807) collected from the small Krestovka River in-flowing into the southwestern part of the Lake. The new species differs from G. acronicus in small shell size of adults, having smaller number of prostate folds (maximal up to 26 in G. takhteevi n. sp. vs. 40 in G. acronicus), a short preputium (approximately twice shorter than the phallotheca), and an elongated bursa copulatrix. The population of Gyraulus takhteevi sp. n. consists of two co-existent morphs: one of them has a narrow shell spire and the second is characterized by wide spire similar to the shell of G. acronicus. One of the two revealed haplotypes of the new species includes both morphs, while the second consists of snails with wide spired shells.
Biology
Lake Baikal is a natural laboratory for the study of species diversity and evolution, as a unique... more Lake Baikal is a natural laboratory for the study of species diversity and evolution, as a unique freshwater ecosystem meeting the all of the main criteria of the World Heritage Convention. However, despite many years of research, the true biodiversity of the lake is clearly insufficiently studied, especially that of deep-water benthic sessile organisms. For the first time, plastic waste was raised from depths of 110 to 190 m of Lake Baikal. The aim of this study was to examine the biological community inhabiting the plastic substrate using morphological and molecular genetic analysis. Fragments of plastic packaging materials were densely populated: bryozoans, leeches and their cocoons, capsules of gastropod eggs, and turbellaria cocoons were found. All the data obtained as a result of an analysis of the nucleotide sequences of the standard bar-coding fragment of the mitochondrial genome turned out to be unique. Our results demonstrate the prospects for conducting comprehensive stud...
BMC Evolutionary Biology
Background: Islands have traditionally been the centre of evolutionary biological research, but t... more Background: Islands have traditionally been the centre of evolutionary biological research, but the dynamics of immigration and differentiation at continental islands have not been well studied. Therefore, we focused on the Japanese archipelago, the continental islands located at the eastern end of the Eurasian continent. While the Japanese archipelago is characterised by high biodiversity and rich freshwater habitats, the origin and formation mechanisms of its freshwater organisms are not clear. In order to clarify the history of the planorbid gastropod fauna, we conducted phylogenetic analysis, divergence time estimation, ancestral state reconstruction, and lineage diversity estimations. Results: Our analyses revealed the formation process of the planorbid fauna in the Japanese archipelago. Most lineages in the Japanese archipelago have closely related lineages on the continent, and the divergence within the Japanese lineages presumably occurred after the late Pliocene. In addition, each lineage is characterised by different phylogeographical patterns, suggesting that immigration routes from the continent to the Japanese archipelago differ among lineages. Furthermore, a regional lineage diversity plot showed that the present diversity in the Japanese archipelago potentially reflects the differentiation of lineages within the islands after the development of the Japanese archipelago. Conclusions: Although additional taxon sampling and genetic analysis focused on each lineage are needed, our results suggest that immigration from multiple routes just prior to the development of the Japanese archipelago and subsequent diversification within the islands are major causes of the present-day diversity of the Japanese planorbid fauna.
![Research paper thumbnail of The History of Manayunkia [Polychaeta: Sedentaria: Sabellidae] propagation in North Eastern Asia](https://attachments.academia-assets.com/81616277/thumbnails/1.jpg)
](Ecological genetics, 2014
т. а. пудовкина © 1 , т. я. ситникова 1 , а. н. матвеев 2 , д. ю. Щербаков 1, 2 shcherbakov dmitr... more т. а. пудовкина © 1 , т. я. ситникова 1 , а. н. матвеев 2 , д. ю. Щербаков 1, 2 shcherbakov dmitriy yuryevich
ZooKeys, 2016
A new gastropod species, Pseudobaikalia michelae Sitnikoiva & Kovalenkova, sp. n., (family Baical... more A new gastropod species, Pseudobaikalia michelae Sitnikoiva & Kovalenkova, sp. n., (family Baicaliidae) is described from Lake Baikal. This is the first new species from the Baicaliidae for forty years. The new species is distinguished from its sister taxa by means of comparative morphology as well as analyses of DNA sequences (mtDNA and an intron of alpha-subunit gene of ATP-synthase). It was found in the southern and central-eastern parts of the lake where it occurs sympatrically with three other baicaliid species. Characters of the female reproductive system (i.e., a long oviduct loop with 2-3 narrow tube-like evaginations) and the aperture (i.e., oval shape with a simple outer lip) place these snails in the genus Pseudobaikalia Lindholm, 1909. The new species is most similar in its shell morphology to the northern Baikal species P. jentteriana (smooth elongated shape) but differs by a more oval aperture that is slightly angled to the columella. Combined mitochondrial and nuclear sequences in a Bayesian analysis showed that all specimens of P. michelae sp. n. form a well-supported clade.
Archiv für Molluskenkunde: International Journal of Malacology, 2013
The karyotype of the endemic Baikal amphipod Poly-acanthiska calceolata Bazikalova, 1937 was anal... more The karyotype of the endemic Baikal amphipod Poly-acanthiska calceolata Bazikalova, 1937 was analysed for the first time. A diploid number (2n=52) and general chromosome morphology (with a median centromere) are typical amongst Gammaridea. A peculiar feature of the karyotype was its pronounced symmetry caused by the presence of metacentric (equal-armed) chromo-somes insignificantly varying in size (from 5 to 8 μm). Sex chromosomes have not been distinguished. Super-numerary B chromosomes were regularly found in the metaphase plates of embryos P. calceolata, and may serve as an adaptive mechanism of this species to per-form migrations to areas of gas hydrate seeps.
The work aims to illustrate the type specimens of the freshwater physid gastropods described by Y... more The work aims to illustrate the type specimens of the freshwater physid gastropods described by Ya.I. Starobogatov with coauthors. The data on 14 described species include the history of the name application in literature, the information about type locality, type depository, localities of subsequent findings, ecology, and comments on some species.
Biology Letters, 2015
Lake Baikal is the deepest, oldest and most speciose ancient lake in the world. The lake is chara... more Lake Baikal is the deepest, oldest and most speciose ancient lake in the world. The lake is characterized by high levels of molluscan species richness and endemicity, including the limpet family Acroloxidae with 25 endemic species. Members of this group generally inhabit the littoral zone, but have been recently found in the abyssal zone at hydrothermal vents and oil-seeps. Here, we use mitochondrial and nuclear data to provide a first molecular phylogeny of the Lake Baikal limpet radiation, and to date the beginning of intra-lacustrine diversification. Divergence time estimates suggest a considerably younger age for the species flock compared with lake age estimates, and the beginning of extensive diversification is possibly related to rapid deepening and cooling during rifting. Phylogenetic relationships and divergence time estimates do not clearly indicate when exactly the abyssal was colonized but suggest a timeframe coincident with the formation of the abyssal in the northern b...
Zhurnal obshcheĭ biologii
It is suggested that existence of "dwarfs" and "giants" among Baikal gastropo... more It is suggested that existence of "dwarfs" and "giants" among Baikal gastropods depends on several factors. "Dwarfs" occurs in habitats 1) where sedimentation rate is low and thick silt layer is absent (the small shell without long periostracal nodules does not allow the animal to stay on the soft sediment surface; 2) where there is hard substratum suitable for laying egg capsules; 3) where there is intensive water exchange assuring supply of food (detritus and phytoplankton). Distribution of "giants" capable to lay egg capsules on their own shells is not confined by availability of hard substratum. They dwell on soft sediments because they have large light shell with high whorl allowing them to migrate on silt surface. "Giants" live in places with high sedimentation rates, constant supply of food (including died fish), and higher degree of water mineralization. "Giants" and "dwarfs" inhabit only oxidized substrat...
Crustaceana, 2014
We examined amphipods collected from aboard the deepwater manned submersibles “Mir-1” and “Mir-2”... more We examined amphipods collected from aboard the deepwater manned submersibles “Mir-1” and “Mir-2” at oil and methane seeps near Cape Gorevoy Utes (Central Baikal). Most of the 23 taxa registered inhabit the entire Lake Baikal within a wide depth range. Two species of the genus Echiuropus are probably new. Leptostenus leptocerus (Dybowsky, 1874), that, until now, was regarded as a rare species, is likely to be an indicator for methane and oil discharge areas. Additional data on the morphology of this species were obtained; cuticular sensory (lateral line organs) and nonsensory microstructures were examined by scanning electron microscopy. The density of nectobenthic amphipods was 5-6 times higher on bitumen mounds than that at neighbouring sites with flat bottom. Maximum density of benthic amphipods was recorded on bacterial mats. No amphipods were observed at the bottom with large oil patches. High density of amphipods at the oil-methane seep is attributed to highly structured habit...
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2000
In Lake Baikal, extremely thin shells are reported as a typical feature of endemic gastropods. Th... more In Lake Baikal, extremely thin shells are reported as a typical feature of endemic gastropods. This statement derived only from observations; no experimental data were available up to now. Therefore, we quantitatively investigated the calcium distribution in the endemic prosobranch gastropod Benedictia baicalensis and compared the results with those of Lithoglyphus naticoides, a near relative, non-endemic, palaearctic species. The shell of the endemic mollusc B. baicalensis consists of 94.9 926.0 mg Ca 2 + /ml animal volume (n=43), and in L. naticoides 865.09 271.5 mg Ca 2 + /ml (n= 10). Calcium contents in the tissue of B. baicalensis vary between different sampling stations and different sampling dates (from 9.49 5.1 (n= 33) to 20.59 8.4 mg Ca 2 + /mg dry weight DW (n =16)) and are only 1/5-1/10 compared to L. naticoides (88.5 939.1 mg Ca 2 + /mg DW (n=9)). But the values for hemolymph calcium concentration and osmolality in both species are identical (B. baicalensis: osmolality: 84.4 95.3 mosm/kg (n= 40); hemolymph calcium concentration: 4.691.7 mmol/l (n=40). L. naticoides: osmolality: 85.0 9 2.0 mosm/kg (n=8); hemolymph calcium concentration: 5.2 95.0 mmol/l (n=40).). This is the first experimental study demonstrating, that-besides a similar hemolymph ionic composition-the Baikalian species is characterized by significantly lower calcium storage in shell and tissue than the nearly related non-endemic species.
A new species of the family Planorbidae is described from the land thermal spring Khakusy, on the... more A new species of the family Planorbidae is described from the land thermal spring Khakusy, on the northeastern shore of Lake Baikal. The description of Gyraulus takhteevi sp. n. includes morphological characters and gene sequences (COI of mtDNA) for the species separation from sister taxon Gyraulus acronicus (A. Férussac, 1807) collected from the small Krestovka River in-flowing into the southwestern part of the Lake. The new species differs from G. acronicus in small shell size of adults, having smaller number of prostate folds (maximal up to 26 in G. takhteevi n. sp. vs. 40 in G. acronicus), a short preputium (approximately twice shorter than the phallotheca), and an elongated bursa copulatrix. The population of Gyraulus takhteevi sp. n. consists of two co-existent morphs: one of them has a narrow shell spire and the second is characterized by wide spire similar to the shell of G. acronicus. One of the two revealed haplotypes of the new species includes both morphs, while the second consists of snails with wide spired shells.
Biology
Lake Baikal is a natural laboratory for the study of species diversity and evolution, as a unique... more Lake Baikal is a natural laboratory for the study of species diversity and evolution, as a unique freshwater ecosystem meeting the all of the main criteria of the World Heritage Convention. However, despite many years of research, the true biodiversity of the lake is clearly insufficiently studied, especially that of deep-water benthic sessile organisms. For the first time, plastic waste was raised from depths of 110 to 190 m of Lake Baikal. The aim of this study was to examine the biological community inhabiting the plastic substrate using morphological and molecular genetic analysis. Fragments of plastic packaging materials were densely populated: bryozoans, leeches and their cocoons, capsules of gastropod eggs, and turbellaria cocoons were found. All the data obtained as a result of an analysis of the nucleotide sequences of the standard bar-coding fragment of the mitochondrial genome turned out to be unique. Our results demonstrate the prospects for conducting comprehensive stud...
BMC Evolutionary Biology
Background: Islands have traditionally been the centre of evolutionary biological research, but t... more Background: Islands have traditionally been the centre of evolutionary biological research, but the dynamics of immigration and differentiation at continental islands have not been well studied. Therefore, we focused on the Japanese archipelago, the continental islands located at the eastern end of the Eurasian continent. While the Japanese archipelago is characterised by high biodiversity and rich freshwater habitats, the origin and formation mechanisms of its freshwater organisms are not clear. In order to clarify the history of the planorbid gastropod fauna, we conducted phylogenetic analysis, divergence time estimation, ancestral state reconstruction, and lineage diversity estimations. Results: Our analyses revealed the formation process of the planorbid fauna in the Japanese archipelago. Most lineages in the Japanese archipelago have closely related lineages on the continent, and the divergence within the Japanese lineages presumably occurred after the late Pliocene. In addition, each lineage is characterised by different phylogeographical patterns, suggesting that immigration routes from the continent to the Japanese archipelago differ among lineages. Furthermore, a regional lineage diversity plot showed that the present diversity in the Japanese archipelago potentially reflects the differentiation of lineages within the islands after the development of the Japanese archipelago. Conclusions: Although additional taxon sampling and genetic analysis focused on each lineage are needed, our results suggest that immigration from multiple routes just prior to the development of the Japanese archipelago and subsequent diversification within the islands are major causes of the present-day diversity of the Japanese planorbid fauna.
Ecological genetics, 2014
т. а. пудовкина © 1 , т. я. ситникова 1 , а. н. матвеев 2 , д. ю. Щербаков 1, 2 shcherbakov dmitr... more т. а. пудовкина © 1 , т. я. ситникова 1 , а. н. матвеев 2 , д. ю. Щербаков 1, 2 shcherbakov dmitriy yuryevich
ZooKeys, 2016
A new gastropod species, Pseudobaikalia michelae Sitnikoiva & Kovalenkova, sp. n., (family Baical... more A new gastropod species, Pseudobaikalia michelae Sitnikoiva & Kovalenkova, sp. n., (family Baicaliidae) is described from Lake Baikal. This is the first new species from the Baicaliidae for forty years. The new species is distinguished from its sister taxa by means of comparative morphology as well as analyses of DNA sequences (mtDNA and an intron of alpha-subunit gene of ATP-synthase). It was found in the southern and central-eastern parts of the lake where it occurs sympatrically with three other baicaliid species. Characters of the female reproductive system (i.e., a long oviduct loop with 2-3 narrow tube-like evaginations) and the aperture (i.e., oval shape with a simple outer lip) place these snails in the genus Pseudobaikalia Lindholm, 1909. The new species is most similar in its shell morphology to the northern Baikal species P. jentteriana (smooth elongated shape) but differs by a more oval aperture that is slightly angled to the columella. Combined mitochondrial and nuclear sequences in a Bayesian analysis showed that all specimens of P. michelae sp. n. form a well-supported clade.
Archiv für Molluskenkunde: International Journal of Malacology, 2013
The karyotype of the endemic Baikal amphipod Poly-acanthiska calceolata Bazikalova, 1937 was anal... more The karyotype of the endemic Baikal amphipod Poly-acanthiska calceolata Bazikalova, 1937 was analysed for the first time. A diploid number (2n=52) and general chromosome morphology (with a median centromere) are typical amongst Gammaridea. A peculiar feature of the karyotype was its pronounced symmetry caused by the presence of metacentric (equal-armed) chromo-somes insignificantly varying in size (from 5 to 8 μm). Sex chromosomes have not been distinguished. Super-numerary B chromosomes were regularly found in the metaphase plates of embryos P. calceolata, and may serve as an adaptive mechanism of this species to per-form migrations to areas of gas hydrate seeps.
The work aims to illustrate the type specimens of the freshwater physid gastropods described by Y... more The work aims to illustrate the type specimens of the freshwater physid gastropods described by Ya.I. Starobogatov with coauthors. The data on 14 described species include the history of the name application in literature, the information about type locality, type depository, localities of subsequent findings, ecology, and comments on some species.
Biology Letters, 2015
Lake Baikal is the deepest, oldest and most speciose ancient lake in the world. The lake is chara... more Lake Baikal is the deepest, oldest and most speciose ancient lake in the world. The lake is characterized by high levels of molluscan species richness and endemicity, including the limpet family Acroloxidae with 25 endemic species. Members of this group generally inhabit the littoral zone, but have been recently found in the abyssal zone at hydrothermal vents and oil-seeps. Here, we use mitochondrial and nuclear data to provide a first molecular phylogeny of the Lake Baikal limpet radiation, and to date the beginning of intra-lacustrine diversification. Divergence time estimates suggest a considerably younger age for the species flock compared with lake age estimates, and the beginning of extensive diversification is possibly related to rapid deepening and cooling during rifting. Phylogenetic relationships and divergence time estimates do not clearly indicate when exactly the abyssal was colonized but suggest a timeframe coincident with the formation of the abyssal in the northern b...
Zhurnal obshcheĭ biologii
It is suggested that existence of "dwarfs" and "giants" among Baikal gastropo... more It is suggested that existence of "dwarfs" and "giants" among Baikal gastropods depends on several factors. "Dwarfs" occurs in habitats 1) where sedimentation rate is low and thick silt layer is absent (the small shell without long periostracal nodules does not allow the animal to stay on the soft sediment surface; 2) where there is hard substratum suitable for laying egg capsules; 3) where there is intensive water exchange assuring supply of food (detritus and phytoplankton). Distribution of "giants" capable to lay egg capsules on their own shells is not confined by availability of hard substratum. They dwell on soft sediments because they have large light shell with high whorl allowing them to migrate on silt surface. "Giants" live in places with high sedimentation rates, constant supply of food (including died fish), and higher degree of water mineralization. "Giants" and "dwarfs" inhabit only oxidized substrat...
Crustaceana, 2014
We examined amphipods collected from aboard the deepwater manned submersibles “Mir-1” and “Mir-2”... more We examined amphipods collected from aboard the deepwater manned submersibles “Mir-1” and “Mir-2” at oil and methane seeps near Cape Gorevoy Utes (Central Baikal). Most of the 23 taxa registered inhabit the entire Lake Baikal within a wide depth range. Two species of the genus Echiuropus are probably new. Leptostenus leptocerus (Dybowsky, 1874), that, until now, was regarded as a rare species, is likely to be an indicator for methane and oil discharge areas. Additional data on the morphology of this species were obtained; cuticular sensory (lateral line organs) and nonsensory microstructures were examined by scanning electron microscopy. The density of nectobenthic amphipods was 5-6 times higher on bitumen mounds than that at neighbouring sites with flat bottom. Maximum density of benthic amphipods was recorded on bacterial mats. No amphipods were observed at the bottom with large oil patches. High density of amphipods at the oil-methane seep is attributed to highly structured habit...