Contents: Volume 22 (2) 2023 (Printed 22 November 2023)

Bui T.H., Motokawa M., Biswas J.K., Abramov A.V., Ly N.T., Vu T.D., Nguyen T.S.

P. 85–96

The patterns of morphometric variation in external body and skull characters of two Asiatic water shrews (Chimarrogale himalayica and C. varennei) from Vietnam were analysed using different indices of variability. A total of 28 specimens were studied. Univariate, multivariate, and allometric analyses were conducted on 21 measurements of 26 skulls, while univariate analysis was conducted on three external measurements of 24 specimens. An external comparison showed that C. himalayica is larger than C. varennei. The mean (M) of skull measurements was used as an independent variable to regress the coefficient of variation (CV) and standard deviation (SD). The CVs did not differ significantly between two species and exhibited an inverse relationship with the M of skull measurements. CV trends of major functional parts of the skull showed that incisor length, brain-case size, postglenoid breadth, and mandible length presented opposing differences between the two species. In addition, C. himalayica had the highest allometric coefficient for the overall skull length, whereas C. varennei had the highest allometric coefficient for the postorbital region. Our study also revealed that the facial musculoskeletal system of C. himalayica is more developed than in C. varennei.

Matrosova V.A., Gündüz İ., Ermakov O.A., Demirtaş S., Simonov E.

P. 97-101

Complete mitochondrial genome of paratype specimen of Taurus ground squirrel Spermophilus taurensis was assembled for the first time. We provide data concerning the sequencing, assembly, and annotation of the obtained mitochondrial genome. The studied mitogenome being 16 447 bp in length, and containing 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, an origin of L-strand replication and a control region. Data obtained for the whole mitochondrial genome confirmed sister position of S. taurensis and the closely related species S. citellus on the phylogenetic tree, which was shown earlier on single genes.

Petrova T.V., Kuksin A.N., Putintsev N.I., Lopatina N.V., Lissovsky A.A.

P. 102-119

The narrow-headed vole species complex (subgenus Stenocranius) is represented by at least two cryptic species: Lasiopodomys gregalis and L. raddei. One of L. gregalis lineages (lineage B, inhabiting northern Mongolia and neighbouring territories) forms a secondary contact zone with L. raddei. In the current study, we analysed phylogeographic structure of L. gregalis lineage B by means of sequences of mitochondrial cytochrome b and reconstructed ecological niches of both species at present and in the past. The source of the spread of L. gregalis lineage B was probably the territory of modern western Mongolia and southeastern Tuva. Despite seeming continuity of the geographic range of lineage B, mitochondrial clusters within it turned out to be allopatric or parapatric; the reasons for such spatial structure are not yet clear. Based on the ecological niche modelling, it can be hypothesised that the two studied species reacted differently to climatic fluctuations of the late Pleistocene, and the structure of the modern geographic range of L. gregalis lineage B has formed largely due to inter-specific competitive interactions with L. raddei.

Naumova A.E., Smorkatcheva A.V., Sablina S.A.

P. 120-125

Animals of most species avoid close inbreeding, but the levels of incest avoidance (IA) vary both between and within species. Evolutionary reasons for this diversity are generally unclear. Comparison of IA between closely-related species and between within species categories (sexes, age classes or categories of kin pairs) could provide important tools to test hypotheses on the evolution of IA strategies. In this laboratory study we compared the likelihood of reproduction between mother–son and father–daughter pairs in a monogamous subterranean vole, Lasiopodomys mandarinus. The subterranean lifestyle is associated with impeded mates’ encounters, costly dispersal, and relatively low value of each breeding attempt, which factors are expected to restrain the IA evolution. In polygynous uniparental animals, the predominance of father–daughter inbreeding over mother–son inbreeding is predicted. We aimed to test whether L. mandarinus, which exhibits a partial reversal of sex roles, displays an opposite pattern of asymmetry with a weakened IA between a mother and a son. Against the expectation, reproductive performance was dramatically reduced in both kin combinations. Mandarin vole’s IA strategies follow the pattern typical for non-subterranean species with strong pair bonding, supporting the importance of mating system for IA evolution.

Çetintürk D.

P. 126-136

Dogramaci’s vole, Microtus dogramacii, is an endemic rodent species distributed in the northern region of central Anatolia in Turkey. Existing studies performed at the molecular level have been insufficient to differentiate between M. dogramacii and the “guentheri” group of voles (Microtus hartingi, Microtus guentheri and Microtus qazvinensis). Therefore, M. dogramacii was compared with some other Microtus species in terms of genetic diversity, mean genetic distance values and phylogenetic approaches for the mitochondrial cytochrome-b gene region. The mean genetic distance values between M. dogramacii and other species were 3.2–7.0%. In the Median-joining network, Maximum Likelihood and Bayesian MCMC dendrograms, M. dogramacii was closer to M. qazvinensis and M. hartingi than to M. guentheri and M. socialis. Obtained results, based on the cytochrome-b analyses, suggest that M. dogramacii may be a recently evolved species.

Kostin D.S., Gromov A.R., Lavrenchenko L.A.

P. 137-141

Within the frame of the current study, we assembled and annotated seven mitochondrial genomes: three of them for the first time obtained for the Altai vole M. obscurus, four belong to the Eastern lineage of common vole M. arvalis. Obtained sequences enlarge amount of available genomic data for two sister vole species that creates the basis for further studies on phylogeny and mechanisms of adaptive mitochondrial DNA introgression, apparently took place within the group under study.

Tserendavaa P., Erdenechimeg E., Hackländer K., Samiya R., Sheftel B.I., Undrakhbayar E., Nomin A., Muehlenberg M.

P. 142-149

The reed vole Alexandromys fortis is a small herbivorous species primarily inhabiting open meadows in northern and central Eurasia. While the reed vole population in Mongolia is classified as least concern, there are limited information available about this species. To address this knowledge gap, a survey was conducted in the Khonin Nuga region of West Khentey, along the Yeroo River in Northern Mongolia, to assess the physical characteristics and population structure of reed voles. Over the course of a 12-year study, the reed vole population exhibited significant oscillations. Notably, the species demonstrated strong sexual dimorphism, with males consistently displaying larger size than females among all individuals measured. Furthermore, an imbalanced sex ratio was observed, with a greater number of males present both in the captured individuals (male-to-female ratio of 1.19:1) and the adult samples (male-to-female ratio of 1.45:1).

Gromov V.S.

P. 150-161

The article concerns fitness effects of alloparental care, or helping (i.e., assistance of young individuals in rearing offspring that are not their own) in social muroid rodents (Meriones unguiculatus, Microtus ochrogaster, Microtus pinetorum, Lasiopodomys mandarinus, Peromyscus polionotus, and Rhabdomys pumilio) that are characterized by a family-group lifestyle and biparental care. According to inclusive fitness theory, alloparenting may alter both direct and indirect fitness. In particular, helpers may benefit indirectly if breeders that receive assistance subsequently produce more offspring. In laboratory studies, however, neither the presence of alloparents nor greater numbers of alloparents affected litter size at weaning. The results of the experimental studies also provide little support to the hypothesis that breeders benefit directly by increasing their lifetime reproductive success. In some species, helpers may decrease the workload of breeders, but the effects of alloparenting were found to be slight and often mixed. However, there is evidence that alloparental care yields direct benefits to helpers by providing experience that allow them to become more successful parents. It seems unlikely that helping behavior evolved merely to kin selection in consistence with ‘Hamilton’s rule’. A more appropriate explanation is that helping behavior in rodents is a by-product of the evolution of sociality, i.e. the transition to a family-group lifestyle with biparental care. Extended family groups with helpers form due to delayed dispersal of offspring, and the latter may gain direct and/or indirect fitness benefits from staying within their natal groups. Alloparenting could be considered a form of cooperation due to which both breeding pairs and their older offspring being helpers may gain direct or indirect fitness benefits.

Antonevich A.L., Naidenko S.V.

P. 162-171

Most of the felids are tropical nonseasonal breeders, but northern species have adapted to seasonal climate by reproductive seasonality pronounced to a different degree. We review what is known about the reproductive seasonality in felids. The Lynx genus includes the most northern felids — Eurasian and Canada lynx, and also Iberian lynx, and bobcat. Specific seasonal adaptations in lynx reproduction act as a unique Strictly Seasonal Breeding Complex expressed to a different extent among lynx species. This complex includes hormonal and gonadal seasonality, monoestric cycle, and unique persistent corpora lutea. We suggest that adaptation to strictly seasonal breeding is very advantageous in a lynx environment. Still, together with other features of lynx biology, we suppose that it could act as one of the prerequisites for sibling aggression development. However, this hypothesis is preliminary and only aims to consider possible interactions of species-specific reproductive features of lynx.

Trukhanova I.S., Chirkova O.A., Shakhnazarova V.Yu., Gromov V.V., Bakunovich P.M., Kouprianov P.A., Kouprianov A.V., Fedeneva Y.V., Sokolovskaya M.V.

P. 172-181

Based on imagery taken at summer coastal haul-out sites on the islands of the Valaam Archipelago in northern Lake Ladoga in 2019 and 2020, a photo-identification database for the endangered Ladoga ringed seal (Pusa hispida ladogensis) has been developed. We based individual identification on unique patterns visible on the seal pelt and demonstrated the utility of this approach to ringed seal monitoring. The current version of the database contains 537 individual seals. When possible, the sex and age class of individuals were recorded, as well as individual resightings within one day, intra- and inter-seasonal resightings. At the haul-outs, the female-to-male ratio was about 1:1.16, and 2.3% of the animals were young-of-the-year. The intra-season resighting percentage was 2% in 2019 and 2.3% in 2020, whereas the inter-annual resighting rate was only 1.3%, indicating low haul-out site fidelity and substantial rotation across seal groups using the islands during the open-water season.