Contents: Volume 22 (1) 2023 (Printed 4 May 2023)

Malikov D.G., Golovanov S.E.

P. 1-15

The present paper fills the gap in the Middle Pleistocene fossil record of small mammals in the southeast of Western Siberia. We describe small mammals faunas from localities of the second half of the Middle Pleistocene. Faunal remains were derived from alluvial deposits from three geological sections in the Cis-Altai Plain. The small mammals localities occupy a clear stratigraphic position between the deposits of the lower Middle Pleistocene and the loess-paleosol deposits of the Upper Pleistocene. We describe a rich faunal association of the post-Vyatkinian (=post-Tiraspolian/post-Cromerian) appearance. The fauna is dominated by steppe species of small mammals, Spermophilus sp., Lagurus lagurus, and Stenocranius gregalis. The evolutionary level of small mammal fauna is in good agreement with stratigraphic structure of geological sections. The most probable age of this fauna is the first half of the late Middle Pleistocene (MIS 11-9). The steppe lagurine and the narrow-headed vole morphology are in good agreement with this dating. Open steppe landscapes were reconstructed for the studied faunal localities.

Volodin I.A., Kozhevnikova J.D., Ilchenko O.G., Sapozhnikova S.R., Volodina E.V.

P. 16-23

Mammals not experiencing vocal learning may slightly modify their voice calls (produced by vibration of the vocal folds) towards a higher similarity with conspecific groupmates. This pilot study is the first focused on interspecies social effects on whistle vocalizations (ultrasounds produced by turbulence at the vocal tract). Pup cross-fostering was applied between two related gerbil species Meriones unguiculatus and M. vinogradovi, producing acoustically different ultrasonic contact calls when adult (higher-frequency in M. vinogradovi). Calls of 3 survived foster individuals (2 M. unguiculatus and 1 M. vinogradovi) and of 22 control non-foster individuals raised by their own species (10 M. unguiculatus and 12 M. vinogradovi) were analysed bioacoustically. Call duration of non-fosters did not differ between species, whereas the fundamental and peak frequencies were lower in non-foster M. unguiculatus. Foster M. unguiculatus produced calls shorter and higher in the fundamental and peak frequencies than non-foster M. unguiculatus. Foster M. vinogradovi produced calls shorter and higher in the beginning and minimum fundamental frequencies than non-foster M. vinogradovi. We discuss that the observed trend, towards higher-frequency calls, was only expectable for foster M. unguiculatus, whereas the same trend observed in foster M. vinogradovi was opposed to the expected. These findings provide the possibility that the acoustic properties in foster M. unguiculatus are changed by social effect which apparently lacked on the calls of the foster individual M. vinogradovi. We discuss that these limited data on gerbils are consistent with published contradictory data on laboratory mice strains.

Ermakov O.A., Brandler O.V., Ivanov A.Yu., Ivanova A.D., Kesyan A.A., Khalidov A.Kh., Lotiev K.Yu., Lukonina S.A., Tsapko N.V., Titov S.V.

P. 24-31

Little ground squirrel (Spermophilus pygmaeus) typically inhabit semi-deserts and dry steppes of the European plains and Kazakhstan. Range-wide latitudinal distribution along with major river separation zones makes this species a proper model for testing the riverine barrier hypothesis. For the first time, we have evaluated genetic variation in little ground squirrel populations throughout its range based on the analysis of cytochrome b gene sequences. A high level of genetic diversity (4.9%) among “western” and “eastern” populations of the little ground squirrel has evidenced the Volga River to be an effective biogeographic barrier. A barrier role of the Ural River is expressed to a lesser extent, and the Don River has neither effect on the restriction to gene flow and phylogeographic structure. The genetic diversity data has confirmed the hypothesis on S. pygmaeus speciation in the long-term Ciscaucasia refugium, and the appearance of the mountain ground squirrel (S. p. musicus) in the Middle Pleistocene.

Khrushchova A.M., Vasilieva N.Yu., Shekarova O.N., Vasilieva N.A., Rogovin K.A.

P. 32-43

In 68 pairs of Campbell’s hamster (Phodopus campbelli Thomas, 1905) caged outdoors, under natural day length and temperature, we considered ambient temperatures, body mass and its change as proximate factors of torpor bouts. The ultimate effects of daily torpor were assessed by the mortality of animals and the number of litters born. Both sexes showed daily torpor irregularly from November 2010 to January 2011 with a maximum in December; 37% of males and 39% of females did not show any torpor at all. There was no link between torpor episodes and low ambient temperatures during the whole winter, when considering the total winter period, however, we did find a significant link between ambient temperature and torpor use in December. Daily torpor in Campbell’s hamsters we studied seems not to be an obligate, strictly deterministic physiological response to critical body condition when the body reserves are close to exhaustion. Among males, we observed a tendency towards a positive correlation of the number of torpor bouts on the initial body mass in September. The body mass loss from September to December was positively correlated to September’s body mass. Torpor pattern did not affect the hamsters’ survival and the number of litters born. We conclude that our results do not indicate daily torpor in Campbell’s hamster as an obligate life history adaptation, which should unconditionally enhance ultimate fitness consequences.

Pilevich D.S., Yalkovskaya L.E., Sibiryakov P.A., Borodin A.V.

P. 44-52

As a result of the analysis of the cyt b complete sequences of 26 harvest mice Micromys minutus from 13 localities of the Urals and Western Siberia, the distribution boundaries and genetic diversity of the Russia phylogeographic lineage have been clarified. The distribution of the lineage in the south of the central part of Northern Eurasia from the Tyva Depression to the Southern Trans-Urals coincides with the southern boundary of the species range. The northern area of species distribution was previously considered to be limited to the taiga zone. However, our study showed that the northern boundary of the range passes through the subpolar regions of the West Siberian Plain and Cis-Urals in the zone of modern forest-tundra. Phylogeographic analysis with the inclusion of new data has confirmed the existence of four previously described phylogenetic lineages (Europe, Russia, Taiwan, Korea-Japan), the genetic diversity and demographic analysis of which have confirmed the suggestion that the modern species genetic structure and range has formed during the Late Pleistocene–Holocene period.

Stakheev V.V., Khlyap L.A., Mironova T.A., Abramson N.I., Malygin, V.M., Lissovsky A.A.

P. 53-61

We studied a sample of occurrence localities of two sibling species: the common Microtus arvalis and the East-European vole M. rossiaemeridionalis, identified genetically or cytogenetically, by species distribution modelling (MaxEnt) methods for the territory of Eastern Europe. Climate data and remote sensing data were used as predictors. Despite of some difference in modern distribution of the species, we did not find any significant difference between ecological preferences of the common and East-European voles. Thus, we have tried to explain modern differences in distribution without ecological arguments. Such difference can be caused by historical reasons, when one of the species holds the territory on the basis of the founder principle or density-dependent spatial structuring. Another possibility is a segregating based on the behavioral or physiological peculiarities of the vole species. The low AUC values of our spatial models can be explained taking into account the dynamic change of landscapes of the Russian Plain, where the zone of sympatry of the sibling species is located, as well as by poor knowledge of species distribution details.

Korablev P.N., Korablev N.P., Zinoviev A.V., Korablev M.P.

P. 62-73

Although wolves, dogs and their hybrids can be discerned by genetic analysis, the study of morphology-morphometry to discern the three groups remains important as genetic analysis is not always possible or too expensive. In this study we aim to differentiate the three subgroups by analyzing two morphometric and ten morphological characteristics in 329 canid skulls. After morphometric-morphologic allocation, we applied genetic analysis on 108 skulls based on 11 autosomal microsatellites to verify the morphometric-morphologic results. In 30 specimens genetic tests were unsuccessful. In addition, 23 samples from wolves (14 skins and 9 muscle samples) as well as 32 samples from modern dogs (8 hair and 24 blood samples) were used as reference data in the genetic analysis. Based on morphology-morphometry we diagnosed 322 wolves, four dogs and three hybrids. Genetic testing was done on 78 specimens: one presumed dog, three presumed hybrids and 74 of the wolves, as diagnosed morphologically before. All, but one, morphologically diagnosed wolves, were confirmed as being wolves genetically. That one was identified a hybrid genetically. From the four morphological dogs one was confirmed genetically, the other three had failed genetic tests. Of the three morphological hybrids one was genetically a dog. The results of this study indicate the absence of reliable morphological criteria for identifying skulls of hybrids, which is a consequence of the high morphological variability in dogs and wolves. However, the use of morphometric and morphological characteristics, helps to narrow the numbers of skulls that require genetic analysis for more precise identification.

Ismail M.E., Fedutin I.D., Ivkovich T.V., Filatova O.A.

P. 74-83

Killer whale is an apex predator which plays an important role in marine ecosystems. In the Russian waters, killer whales are represented by two ecotypes — fish-eaters (R-type) and marine-mammal eaters (T-type). In our study we focused on two study areas: Commander Islands and Avacha Gulf of Kamchatka. The numbers of some species of marine mammals in the North Pacific are declining, and mammal-eating killer whales are often blamed for the decline. For example, the decline in the numbers of sea otters in Alaska is linked by some specialists to the increased predation of mammal-eating killer whales. In the Commander Islands, a decrease in the numbers of sea otters has also been observed in recent years. We analyzed the number of sightings of killer whales in the Commander Islands and Avacha Gulf to find out whether the occurrence of mammal-eating killer whales increased during the study period 2008–2021. We found no definite trend in the occurrence of mammal-eating killer whales over time in both areas. We conclude that our data provide no support to the hypothesis that the decrease of sea otter numbers in the Commander Islands was caused by the increased killer whale predation.