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Parthenogenetic species of Caucasian rock lizards of the genus Darevksia are important evidence for reticulate evolution and speciation by hybridization in vertebrates. Female-only lineages formed through interspecific hybridization have been discovered in many groups. Nevertheless, critical mechanisms of oogenesis and specifics of meiosis that provide long-term stability of parthenogenetic species are still unknown. Here we report cytogenetic characteristics of somatic karyotypes and meiotic prophase I nuclei in the diploid parthenogenetic species Darevskia unisexualis from the new population "Keti" in Armenia which contains an odd number of chromosomes 2n = 37, instead of the usual 2n = 38. We revealed 36 acrocentric chromosomes and a single metacentric autosomal chromosome, resulting from Robertsonian translocation. Comparative genomic hybridization revealed that chromosome fusion occurred between two chromosomes inherited from the maternal species, similar to another parthenogenetic species D. rostombekowi. To trace the chromosome behaviour in meiosis, we performed an immunocytochemical study of primary oocytes' spread nuclei and studied chromosome synapsis during meiotic prophase I in D. unisexualis based on analysis of synaptonemal complexes (SCs). We found meiotic SC-trivalent composed of one metacentric and two acrocentric chromosomes. We confirmed that the SC was assembled between homeologous chromosomes inherited from two parental species. Immunostaining of the pachytene and diplotene nuclei revealed a mismatch repair protein MLH1 loaded to all autosomal SC bivalents. Possible mechanisms of meiotic recombination between homeologous chromosomes are discussed.

The article explores QSPR models for predicting the heat capacity of chemicals in the aldehyde family. The study of the heat capacity parameter is carried out using the developed models using the following factors: topological indices; structural descriptors; information index associated with the Shannon function. Computational experiments were performed showing the high efficiency of the proposed QSPR dependencies.

Open access to occurrence records of the most dangerous invasive species in a standardised format have important potential applications for ecological research and management, including the assessment of invasion risks, formulation of preventative and management plans in the context of global climate and land use changes in the short and long perspective. The striped field mouse (Apodemus agrarius Pallas, 1771) is a common species in the temperate latitudes of the Palaearctic. Due to land use and global climate changes, several waves of expansion of the range of this species have been observed or inferred. By intrusion into new regions, the striped field mouse has become an alien species there. Apodemus agrarius causes significant harm to agriculture and is one of the most important pests of grain crops. In tree nurseries, A. agrarius destroys seeds of valuable tree species and gnaws at the bark of saplings of broadleaf species and berry bushes. It is one of the most epidemiologically important rodents, involved in the circulation of the causative agents of haemorrhagic fever with renal syndrome (HFRS) and many other zoonotic infections. The foregoing allows us to classify the striped field mouse as a dangerous invasive alien species in the expanding part of the range. A lot of data accumulated for this species are of interest from both ecological and applied points of view. The accumulation and aggregation of data on the occurrence records of A. agrarius is relevant for the study of ecology, biogeography and construction of the spatial distribution and ecological niche models in the context of global climate change. We have created a dataset of 1603 occurrence records of this species, collected from 1936 to December 2020 by various zoologists, previously published or original. These records relate to a significant part of the striped field mouse’s range in Russia (1264 records) and neighbouring countries (339 records). The dataset shows the position of the northern and central parts of A. agrarius range, the disjunction of the range in Transbaikalia and isolated populations in the north of the range. The data were obtained in different formats from literature, indicating different degrees of accuracy of geographic coordinates and with several variations of the species' name. In the process of aggregating and fixing errors, we created a set of georeferenced occurrence records, adopted a controlled vocabulary, removed duplicates and standardised the format of records using unified data structure. We examined the dataset for inconsistencies with the taxonomic position of A. agrarius and removed the incorrect records. This paper presents the resulting dataset of A. agrarius occurrence records in the territory of Russia and neighbouring countries in a standardised format. This is a validated and comprehensive dataset of occurrence records of A. agrarius, including both our own observations and records from literature. This dataset is available for extension by other researchers using a standard format in accordance with Darwin Core standards. In different countries, there are a lot of occurrence records for the striped field mouse, but the overwhelming part of them is presented in separate literary sources, stored in the form of maps and in zoological collections. Prior to this project, such information was not available to a wide range of researchers and did not allow the use of these spatial data for further processing by modern methods of analysis, based on geographic information systems (GIS technologies). The created dataset combines species occurrence records of many Soviet zoologists who studied the distribution of the striped field mouse over a significant part of its recent range, in Russia and neighbouring countries (within the former USSR). The final set of records was created by combining the species occurrence records using a uniform data structure, checking geographic coordinates and removing duplicate and erroneous records. The dataset expands the available information on the spatial and temporal distribution of the dangerous invasive species in Russia and neighbouring countries of the former USSR (Estonia, Latvia, Lithuania, Belarus, Ukraine, Moldova, Georgia, Azerbaijan, Kazakhstan and Kyrgyzstan).

Background Caucasian rock lizards of the genus Darevskia are unique taxa, including both bisexual and parthenogenetic species. The parthenogenetic species have originated as a result of natural hybridisation between females and males of different bisexual species. The species involved in interspecific hybridisation are called parental. However, sympatric zones (SZ) of unisexual and bisexual rock lizards of the Caucasus are still poorly studied, although they are very important for understanding the role of hybrid individuals of different origin in reticulate evolution. This paper presents the location of the SZs of parthenogenetic and their parental bisexual rock lizards of the genus Darevskia in Armenia and adjacent territories of Georgia and Nagorno-Karabakh. We summarised the locations of the SZs identified from 1957 to the present, based on our field survey data gathered in 2018-2019 and records from publications and museum collections. This dataset includes 39 SZs of three types: SZ of parental bisexual species, SZ of parental species with unisexual species and SZ of the parthenogenetic species. For each zone, species composition, geographical and altitudinal distribution are presented. New records expand our knowledge of the geographical and altitudinal distribution of SZs in these species and provide additional data for understanding the mechanisms of reticulate evolution and hybridogeneous speciation in the past, present and future. New information The new records, including geographical and altitudinal distributions of three types of SZs, are presented, which expand the previously-known list to 39 locations of contact zones for parthenogenetic and its bisexual parental species of rock lizards of the genus Darevskia in Armenia and the adjacent territories of Georgia and Nagorno-Karabakh.

The results of recent studies on invasions of alien species in the Holarctic are given in a review format. Most of these studies were presented at the Fifth International Symposium “Invasions of Alien Species in the Holarctic,” which was held in Russia in 2017. For this review, we used recent publications in the Russian Journal of Biological Invasions and other journals. The main trends in studies of invasions of alien species in the Holarctic are highlighted.

The analysis of restoration of the number of Eurasian beaver (Castor fiber L.) in the reserves of the European part of Russia and the prediction of possible changes in ecosystems after its introduction into the reserves (Laplandsky, Darwinsky, Prioksko-Terrasny, Central Forest, Oksky, Mordovsky, Khopersky, Voronezhsky and Rdeysky) is presented. The purpose of this work is to analyse the patterns of restoration of the number of beavers based on long-term ground-based observation data and a qualitative description of possible changes in ecosystems after the introduction of beavers. The analysis of the population dynamics of the beavers in the reserves located in the north, south and in the centre of the range was carried out based on long-term monitoring data from 15 to 80 years. It is shown that the patterns of beaver population dynamics can be described using four types of patterns: eruptive; single-stage with quasi-periodic oscillations, multi-stage with quasi-periodic oscillations and a logistic trend of population change with periodic oscillations around it. It is revealed that the impact of beavers on landscapes depends on the population density, terrain features and forage resources of the territory. It is shown that in the future the beaver remains a constant component of ecosystems in the major part of the range. Possible changes in the biotic and abiotic characteristics of ecosystems as a result of beaver activity are analysed.

The article provides data on allelic and genotypic diversity of Ukrainian and Armenian populations of a parthenogenetic lizard of Darevskia armeniaca. The individual genotypes of studied specimens were established due to combination of alleles of three microsatellite loci. It is supposed that in the introduced Ukrainian population after the invasion two new genotypes appeared. Molecular mechanisms of the emergence of these new genotypes are suggested. Values of observed heterozygosity and genetic Fst-distances for the introduced Ukrainian population, native Armenian population and group of other Armenian populations are provided.

One of the main questions-in the study of the unisexual (parthenogenetic) species of vertebrates is the determination of their genetic diversity. Nuclear and mitochondrial genetic markers can be used for this purpose. One of the most effective genetic markers is the microsatellite DNA, which mutates at a high rate. Development and characteristics of such markers are necessary in studies of parthenogenetic species. In this work, the analysis of the allele polymorphism of three microsatellite loci was performed for the first time via locus-specific PCR in the populations of parthenogenetic species Darevskia rostombekovi (n = 42) and bisexual parental species D. raddei (n = 6) and D. portschinskii (n = 6). All examined individuals of the parthenogenetic D. rostombekovi were heterozygous. Two to five alleles, depending on the locus, were found in the studied populations of the parthenogenetic species. It was shown that the differences were due to the varying structure of the microsatellite cluster and to single nucleotide substitutions at fixed distances in the DNA regions adjacent to the cluster. The allele structure variations form haplotype markers specific for each allele and inherited from the parental bisexual species. It was determined which alleles of the parthenogenetic species were inherited from the maternal species and which from the paternal species. Characteristics of distribution, frequency of occurrence, and combination of alleles of microsatellite loci, which determine the distinctive features of each D. rostombekovi population were obtained. The data can be used in the future to determine the clonal diversity and possible ways of its formation in the populations of the parthenogenetic species D. rostombekovi.

Among vertebrates, true parthenogenesis is known only in reptiles. Parthenogenetic lizards of the genus Darevskia emerged as a result of the hybridization of bisexual parental species. However, uncertainty remains about the mechanisms of the co-existence of these forms. The geographical parthenogenesis hypothesis suggests that unisexual forms can co-exist with their parental species in the &ldquo, marginal&rdquo, habitats. Our goal is to investigate the influence of environmental factors on the formation of ecological niches and the distribution of lizards. For this reason, we created models of species distribution and ecological niches to predict the potential geographical distribution of the parthenogenetic and its parental species. We also estimated the realized niches breadth, their overlap, similarities, and shifts in the entire space of predictor variables. We found that the centroids of the niches of the three studied lizards were located in the mountain forests. The &ldquo, maternal&rdquo, species D. mixta prefers forest habitats located at high elevations, &ldquo, paternal&rdquo, species D. portschinskii commonly occurs in arid and shrub habitats of the lower belt of mountain forests, and D. dahli occupies substantially an intermediate or &ldquo, position along environmental gradients relative to that of its parental species. Our results evidence that geographical parthenogenesis partially explains the co-existence of the lizards.

The article presents the genetic parameters of the populations of lizards of the Darevskia raddei complex (D. raddei nairensis and D. raddei raddei) and the populations of D. valentini calculated on the basis of the analysis of variability of 50 allelic variants of the three nuclear genome microsatellite-containing loci of 83 individuals. It was demonstrated that the Fst genetic distances between the populations of D. raddei nairensis and D. raddei raddei were not statistically significantly different from the Fst genetic distances between the populations of different species, D. raddei and D. valentini. At the same time, these distances were statistically significantly higher than the Fst distances between the populations belonging to one species within the genus Darevskia. These data suggest deep divergence between the populations of D. raddei raddei and D. raddei nairensis of the D. raddei complex and there arises the question on considering them as separate species.

The all-female Caucasian rock lizard Darevskia rostombekowi and other unisexual species of this genus reproduce normally via true parthenogenesis. Typically, diploid parthenogenetic reptiles exhibit some amount of clonal diversity. However, allozyme data from D. rostombekowi have suggested that this species consists of a single clone. Herein, we test this hypothesis by evaluating variation at three variable microsatellite loci for 42 specimens of D. rostombekowi from four populations in Armenia. Analyses based on single nucleotide polymorphisms of each locus reveal five genotypes or presumptive clones in this species. All individuals are heterozygous at the loci. The major clone occurs in 24 individuals and involves three populations. Four rare clones involve one or several individuals from one or two populations. Most variation owes to parent-specific single nucleotide polymorphisms, which occur as heterozygotes. This result fails to reject the hypothesis of a single hybridization founder event that resulted in the initial formation of one major clone. The other clones appear to have originated via post-formation microsatellite mutations of the major clone.

В статье исследуются QSPR модели предсказания теплоемкости химических веществ семейства альдегидов. Исследование параметра теплоемкости осуществляется с помощью разработанных моделей с использованием следующих факторов: топологических индексов; структурных дескрипторов; информационного индекса, связанного с функцией Шеннона. Проведены вычислительные эксперименты, показывающие высокую эффективность предложенных QSPR зависимостей.

Our goal is to assess consequences of the introduction of alien North American (Castor сanadensis (Cc)) beaver into the Nature Reserves inhabited by Eurasian beaver (Castor fiber (Cf)) in European Russia using a mathematical model. For this reason, we have developed a two-species model of population dynamics. Long-term (1934–2015) monitoring data on Cf population dynamics in six Nature Reserves are used in computer modelling of competitive interactions between native Cf and alien Cc. The Reserves are located in the European part of Russia in the north, south, and central part of Cf range. We have simulated the dynamics of both species populations after the introduction of Cc into the habitats occupied by Cf. The model demonstrates that Cf is displaced by Cc in all the Reserves after the introduction of 2 – 24 individuals of Cc. However, the duration of exclusion of one species by the other varies as a function of ecological conditions, initial number of individuals, and fecundities. Our model shows that, in case of introduction of 12 Cc beavers, the size of Cf population starts to decrease after 31–146 years as a result of competition. We study the conditions providing the coexistence of both species and find that Cc population dynamics after Cf exclusion can be described by four patterns: irruptive (Lapland Reserve), single-stage (Prioksko-Terrasny Reserve), multi-stage (Darwin, Central-Forest, and Khoper Reserves) and logistic population growth (Oka Reserve). Species biology in terms of the fecundity, family size, rate of individual development until sexual maturity, life-span, and the age structure of populations are compared between species to detect the mechanisms providing the competitive advantage of Cc over Cf.