Online Library. Theme: Biology (p.4)
Found: 72
Found: 72
| Title: | Riverine barriers and geographic variation in little ground squirrel (Spermophilus pygmaeus, Sciuridae, Rodentia) based on mitochondrial cytochrome b gene sequences |
| Author: | Ермаков Олег Александрович Иванов Александр Юрьевич Титов Сергей Витальевич |
| Type: | Article |
| Kind: | Electronic copy |
| Publication date: | 2023 |
| Publishing house: | KMK Scientific Press |
| Title: | Species and trait-based reconstructions of the hydrological regime in a tropical peatland (Central Sumatra, Indonesia) during the Holocene using Testate Amoebae |
| Author: | Malysheva Elena |
| Type: | Article |
| Kind: | Electronic edition |
| Annotation: | Paleoecological reconstructions of hydrological regimes in tropical peatlands during the Holocene are important for the estimation of their responses to changing environments. However, the application of some widely used proxies, such as testate amoebae, is hampered by poor knowledge of their morphology and ecological preferences in the region. The aim of this study is to describe the morphospecies composition of sub-fossil testate amoebae in deposits of a tropical peatland in Central Sumatra (Indonesia) during the Holocene and reconstruct the hydrological regime using morphospecies- and functional-trait-based approaches. In total, 48 testate amoeba morphospecies were observed. Based on morphospecies composition, we distinguished three main periods of peatland development (13,400–8000, 8000–2000, 2000 cal yr BP–present). The application of the morphospecies-based transfer function provided a more reliable reconstruction of the water regime in comparison to the functional trait-based one. The weak performance of the latter might be related to the poor preservation of shells and the greater variation in the functional traits in sub-fossil communities as compared to the training set and linear modeling approach. These results call for future studies on the functional and morphospecies composition of testate amoebae in a wider range of tropical peatlands to improve the quality of hydrological reconstructions. |
| Publication date: | 2022 |
| Publishing house: | Multidisciplinary Digital Publishing Institute (MDPI) |
| Title: | Species Diversity and Driving Factors of Benthic and Zooplanktonic Assemblages at Different Stages of Thermokarst Lake Development: A Case Study in the Lena River Delta (Middle Siberia) |
| Author: | Esaulov Anton |
| Type: | Article |
| Kind: | Electronic copy |
| Publication date: | 2023 |
| Publishing house: | MDPI |
| Title: | Strigea robusta (Digenea: Strigeidae) infection effects on the gonadal structure and limb malformation in toad early development |
| Author: | Ермаков Олег Александрович |
| Type: | Article |
| Kind: | Electronic copy |
| Annotation: | The anomaly P is a mass morphological anomaly reported in some water frog populations across Europe. It was found that polydactyly is only a mild attenuated form of heavy cases of the anomaly P syndrome, which have strong deformations of the hindlimbs and, partly, forelimbs. It was shown that the anomaly P is caused by the trematode Strigea robusta and this syndrome can be considered as a special case of strigeosis in amphibians. The anomaly P for a long time considered to be specific for water frogs of the genus Pelophylax. Herein, we describe polydactyly and heavy forms of the anomaly P syndrome in toads of the genera Bufo and Bufotes, as a result of exposure to S. robusta cercariae. A total of 150 tadpoles of Bufo bufo, 60 tadpoles of Bufotes viridis, and 60 tadpoles of Bufotes baturae were divided into five experimental and four control groups (30 tadpoles in each group). All anomalies in the toads were similar to those observed in water frogs. The survival of tadpoles in the experimental groups was 76%. The anomaly P was observed in 57.9% of toad tadpoles (51.8% of mild forms and 6.1% of heavy forms). The occurrence of the anomaly P varied among groups from 19% to 78%. Heavy forms of the anomaly P were found in all experimental groups. We described rare asymmetrical cases of the anomaly P. According to severe modification of limb morphology, we supposed changes of gonadal morphology (any modifications of the germ and somatic cells). The gonadal development of infected tadpoles was however the same as in uninfected toad tadpoles, and heterochromatin distribution within gonocytes had no differences as well. It seems like the parasite doesn't have any effect on the gonadal development of the toads. The lack of heavy forms in natural populations of toads, as well as a development of gonads were discussed. |
| Publication date: | 2022 |
| Publishing house: | Wiley |
| Title: | Strigea robusta causes polydactyly and severe forms of Rostand's anomaly P in water frogs |
| Author: | Ермаков Олег Александрович Иванов Александр Юрьевич |
| Type: | Article |
| Kind: | Electronic copy |
| Annotation: | Cases of polydactyly in natural populations of amphibians have attracted great interest from biologists. At the end of the 1940s, the French biologist Jean Rostand discovered a polymorphic syndrome in some water frog (Anura: Pelophylax) populations that included polydactyly and some severe morphological anomalies (he called it 'anomaly P'). The cause of this anomaly remains unknown for 70 years. In a previous study, we obtained anomaly P in the laboratory in tadpoles of water frogs that developed together with molluscs Planorbarius corneus (Mollusca: Gastropoda) collected in the field. We thus proposed the 'trematode hypothesis', according to which the infectious agent responsible for anomaly P is a trematode species.MethodsMetacercariae from tadpoles with anomaly P were identified using ITS2 gene sequencing as Strigea robusta (Trematoda: Strigeidae). To verify teratogenic features of the species, cercariae of S. robusta were tested for the possibility to cause anomalies. Identification of cercariae species was made using morphological and molecular methods (sequencing of ITS2 and 28S rRNA). The tadpoles were exposed to parasites at four doses of cercariae (control, low, medium and high) and divided into two groups: "early" (at 25-27 Gosner stages) and "late" (at 29-34 Gosner stages) exposure. Results A total of 58 (72.5%) tadpoles survived until metamorphosis under the dose-dependent experiment with the trematode S. robusta. Differences in the survival rates were observed between the exposed and unexposed tadpoles both in the group of "early" tadpoles and "late" tadpoles. The exposure of tadpoles to the cercariae of S. robusta induced anomaly P in 82% of surviving tadpoles. The severe forms developed only in "early" stages under all doses of cercariae exposure. Polydactyly predominantly developed in the "late" stages; under a light exposure dose, polydactyly also developed in "early" tadpoles. Laboratory-hatched tadpoles reared together with infected snails had different rates of survival and complexity of deformations associated with the period of coexistence. ConclusionsThe experiments with direct cercariae exposure provide compelling evidence that S. robusta leads to anomaly P in tadpoles of water frogs. The manifestation of anomaly P turned out to be dependent on the stage of development, cercariae dose, and the location of the cysts. |
| Publication date: | 2020 |
| Publishing house: | BioMed Central Ltd. |
| Title: | Testate amoebae (Amphitremida, Arcellinida, Euglyphida) in Sphagnum bogs: The dataset from Eastern Fennoscandia |
| Author: | Malysheva Elena Чернышов Виктор Александрович Комаров Александр Александрович Esaulov Anton |
| Type: | Article |
| Kind: | Electronic copy |
| Annotation: | The paper describes a dataset, comprising 236 surface moss samples and 143 testate amoeba taxa. The samples were collected in 11 Sphagnum-dominated bogs during frost-free seasons of 2004, 2007, 2009, 2017, and 2022. For the whole dataset, the sampling effort was sufficient in terms of observed species richness (143 species in total), though a regional species pool is deemed to be discovered incompletely (143 species is its lower 95 % confidence limit using Chao’s estimator). The local community composition demonstrated high heterogeneity in a reduced ordination space. It supports the opinion that the high versatility of bog ecosystems should be taken into account during ecological studies. |
| Publication date: | 2023 |
| Publishing house: | MDPI |
| Title: | The Effects of Vegetation and the Environment on Testate Amoeba Assemblages in Sphagnum Peatlands in the Northern Caucasus Mountains |
| Author: | Esaulov Anton |
| Type: | Article |
| Kind: | Electronic copy |
| Publication date: | 2023 |
| Publishing house: | MDPI |
| Title: | The incidence of the anomaly P syndrome in water frogs (Anura, Ranidae, Pelophylax) from the Middle Volga River (Russia) |
| Author: | Ермаков Олег Александрович |
| Type: | Article |
| Kind: | Electronic copy |
| Annotation: | The anomaly P is a widespread morphological anomaly, which occurs in some groups of amphibians, caused by the trematode parasite Strigea robusta (Digenea: Strigeidae). This anomaly has been previously recorded in water frogs of the genus Pelophylax and toads of the genera Bufo and Bufotes. The anomaly P includes symmetrical polydactyly cases as a mild attenuated form of the complex syndrome, which in severe cases includes strong deformations of hindlimbs and forelimbs. Strigea robusta has a complex 3-host life cycle using planorbid mollusks as the first intermediate hosts, amphibian larvae as the second intermediate hosts, and anatid birds as the definitive hosts. Herein, we described new records of the anomaly P syndrome in water frogs of the genus Pelophylax from the northeastern parts of their ranges. Symmetrical polydactyly (as a mild form of the anomaly P syndrome) was found in 30 individuals of three species of water frogs from seven localities: in 25 individuals of P. lessonae from four waterbodies, in four individuals of P. ridibundus from three waterbodies, and one individual of P. esculentus. In Gusevo pond, three individuals of P. lessonae with severe cases of the syndrome were found. This is the first record of the anomaly P in reliably identified hybridogenetic edible frogs (P. esculentus) that have been identified in nature. Additionally, we provided new data about the occurrence of the anomaly P and the prevalence of the trematode S. robusta in mollusks taken from two water bodies where anomalous water frogs were found. |
| Publication date: | 2023 |
| Publishing house: | PENSOFT PUBLISHERS |
| Title: | The mitochondrial phylogeography of the Crimean endemic lizard Darevskia lindholmi (Sauria, Lacertidae): Hidden diversity in an isolated mountain system |
| Author: | Ермаков Олег Александрович |
| Type: | Article |
| Kind: | Electronic copy |
| Annotation: | The Lindholm rock lizard, Darevskia lindholmi, is the only member of the genus Darevskia whose range is restricted solely to Europe, representing a local endemism found only in the Crimean Mountains. In our study, we investigated the cytochrome b gene (mtDNA) of 101 D. lindholmi sequences from 65 Crimean localities, representing its entire range. We found that D. lindholmi is highly genetically structured, and its range is divided into populations belonging to three mitochondrial lineages. The Lindholm rock lizard populations inhabiting the middle part of the Crimean Mountains (further referred to as the Central lineage) are sharply differentiated from the other two lineages (the Common and the Southwestern lineages), which are present in most of the species range. The genetic distance between the Central lineage and the other two taken together is 4.6%, according to our results, suggesting that the divergence occurred during the Early Pleistocene. The narrowly distributed Southwestern lineage and the widespread Common lineage, on the other hand, are differentiated by 1%. Field observations on the representatives of the main evolutionary groups show that their ecology is also different: the Central lineage is a mesophilic and cold-resistant form, while the other two closely related lineages are more xerophilic and thermophilic. Results of the potential ranges modeling and ecological niche analysis confirm that the genetic lineages occupy different niches of the Crimea. Furthermore, the area of inhabitation of the Central lineage splits the western and eastern parts of the Common lineage range, while the Southwestern lineage is restricted along the coast of the southwestern coast of the peninsula. The long-term co-existence of deeply divergent sister mitochondrial lineages in a relatively small (circa 7,000 km2) isolated mountain system serves as a mesocosm for understanding the speciation process. Our data suggest that the Central lineage warrants further taxonomic investigation. |
| Publication date: | 2021 |
| Publishing house: | Museum of Zoology Dresden |
| Title: | The role of unequilibrium dynamics of the number and genetic structure of populations in interspecifi c interactions of the russet (Spermophilus major Pall.) and the speckled (Spermophilus suslicus Güld.) ground squirrels in a wide zone of sympatry |
| Author: | Титов Сергей Витальевич Чернышова Ольга Валерьевна Zaks Svetlana |
| Type: | Article |
| Kind: | Electronic copy |
| Publication date: | 2024 |
| Publishing house: | Известия Саратовского университета |
| Title: | The Spatial-Genetic Population Structure of Eptesicus nilssonii (Chiroptera, Vespertilionidae) on the Southern Border of Its Range within European Russia |
| Author: | Смирнов Дмитрий Григорьевич |
| Type: | Article |
| Kind: | Electronic edition |
| Annotation: | The spatial and genetic structure of the Eptesicus nilssonii population was studied. The species is characterized by conservatism of wintering sites. The key territories in the gene flow between colonies are swarming sites. After wintering, most individuals fly to a distance not exceeding 15 km, which is confirmed by the positive values of genetic isolation distance (p ≤ 0.05). Females are characterized by natal philopatry, whereas males are characterized by natal dispersal. High genetic diversity and moderate genetic differentiation were found in wintering areas and summer habitat areas. Most intrapopulation groups are heterogeneous, but some show deviations from the Hardy–Weinberg equilibrium (p < 0.05), and inbreeding is possible. |
| Publication date: | 2020 |
| Publishing house: | Pleiades Publishing, Ltd. (Плеадес Паблишинг, Лтд) (Род-Таун) |
| Title: | Traditional multilocus phylogeny fails to fully resolve Palearctic ground squirrels (Spermophilus) relationships but reveals a new species endemic to West Siberia |
| Author: | Ермаков Олег Александрович Титов Сергей Витальевич |
| Type: | Article |
| Kind: | Electronic copy |
| Annotation: | Previous efforts to reconstruct evolutionary history of Palearctic ground squirrels within the genus Spermophilus have primarily relied on a single mitochondrial marker for phylogenetic data. In this study, we present the first phylogeny with comprehensive taxon sampling of Spermophilus via a conventional multilocus approach utilizing five mitochondrial and five nuclear markers. Through application of the multispecies coalescent model, we constructed a species tree revealing four distinct clades that diverged during the Late Miocene. These clades are 1) S. alaschanicus and S. dauricus from East Asia; 2) S. musicus and S. pygmaeus from East Europe and northwestern Central Asia; 3) the subgenus Colobotis found across Central Asia and its adjacent regions and encompassing S. brevicauda, S. erythrogenys, S. fulvus, S. major, S. pallidicauda, S. ralli, S. relictus, S. selevini, and S. vorontsovi sp. nov.; and 4) a Central/Eastern Europe and Asia Minor clade comprising S. citellus, S. taurensis, S. xanthoprymnus, S. suslicus, and S. odessanus. The latter clade lacked strong support owing to uncertainty of taxonomic placement of S. odessanus and S. suslicus. Resolving relationships within the subgenus Colobotis, which radiated rapidly, remains challenging likely because of incomplete lineage sorting and introgressive hybridization. Most of modern Spermophilus species diversified during the Early–Middle Pleistocene (2.2–1.0 million years ago). We propose a revised taxonomic classification for the genus Spermophilus by recognizing 18 species including a newly identified one (S. vorontsovi sp. nov.), which is found only in a limited area in the southeast of West Siberia. Employing genome-wide single-nucleotide polymorphism genotyping, we substantiated the role of the Ob River as a major barrier ensuring robust isolation of this taxon from S. erythrogenys. Despite its inherent limitations, the traditional multilocus approach remains a valuable tool for resolving relationships and can provide important insights into otherwise poorly understood groups. It is imperative to recognize that additional efforts are needed to definitively determine phylogenetic relationships between certain species of Palearctic ground squirrels. |
| Publication date: | 2024 |
| Publishing house: | Academic Press Inc. |