Current methods for assessing stress in animals rely primarily on data collected from males of model rodent species. This is because females are often excluded from studies, as their physiological parameters are considered more variable. However, to accurately assess the well-being of wild populations of small mammals, stress levels in both sexes must be taken into account. To further explore sex differences in adaptation to stress, scientists from the A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences (IEE RAS) studied the response to prolonged, unpredictable stress in wild-type house mice (Mus musculus musculus). These animals, unlike laboratory strains, are not yet genetically adapted to captivity and may respond to stress differently. The mice were exposed to a variety of moderate stressors (1-hour immobilization, 12-hour wet bedding, 1-hour cold at 4°C, 1-hour predator urine odor, etc.) for five weeks, and their performance was then compared with that of a control group. This approach prevented habituation to the stressor, which occurs with repeated exposure to the same stimulus, and also limited the overall intensity of the adverse effects. Figure 1. The effect of chronic unpredictable stress on behavior in two behavioral tests (a, b, c) and fur corticosterone levels (d). Control – control group of mice. CUS – group of mice exposed to chronic unpredictable stress for five weeks. Grooming duration was determined in the open field test, and the total duration and number of immobility episodes (i.e., periods of complete inactivity) were determined in the tail suspension test. The pattern of body weight changes depended on gender: weight gain in stressed females was less than in controls, while no such differences were observed in males. Changes in the weight of organs directly involved in the stress response were also recorded in mice. Behavioral responses under chronic stress also differed by gender. Long-term stressed females were more likely to exhibit behavioral signs of an internal conflict between the desire to explore new things and risk avoidance. Conversely, males, after similar stressful exposures, became more active in the same situation (Fig. 1 a, b, c). Furthermore, higher levels of the stress hormone corticosterone were recorded in the fur of males (Fig. 1 d). "The choice of fur for analysis was not accidental. Fur accumulates stress hormones (glucocorticoids) over weeks or even months, making glucocorticoid levels in fur a more reliable indicator of chronic stress than a single blood hormone measurement," said Tatyana Laktionova, a junior researcher at the Institute of Ecology and Evolution of the Russian Academy of Sciences. Overall, our observations of morphophysiological and behavioral changes suggest that, under identical experimental conditions, female house mice of natural origin are more vulnerable to chronic stress than males. This study was supported by the Russian Science Foundation grant 23-24-00414 (supervised by Senior Researcher V.V. Voznesenskaya). The results of the study were published in the journal Biology (Q1). Related materials: Science.Mail: "Scientists have discovered that mouse stress depends on gender"

For the first time in Russia, a catalog of bowhead whales from the Sea of ​​Okhotsk population has been published. This publication, supported by the Nature and People Foundation, is the result of a unique six-year study by the A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences. The data collected in the catalog will serve as the foundation for the development and implementation of practical measures to protect one of the rarest and most vulnerable marine mammals. Bowhead whales of the Sea of ​​Okhotsk are a small group of endangered whales that spend their entire life cycle in Russian waters. The population numbers no more than 400 individuals. The project to conserve bowhead whales in the Sea of ​​Okhotsk is being implemented by the Nature and People Foundation and the Institute of Ecology and Evolution of the Russian Academy of Sciences in partnership with the Siberian Wellness Foundation "World Around You," JSC "UTLC ERA," and Ilya Trukhanov's KIT Clinic. Since 2020, scientists have been conducting research in key feeding areas of the Okhotsk Sea population of bowhead whales. In the summer and fall, expeditions travel to the Shantar Islands and Shelikhov Bay. Photographs are taken using drones, as identifying the animals from boat photographs is difficult: bowhead whales lack a dorsal fin, rarely expose their tails, and have a predominantly monotone black dorsal coloration. Photo-identification allowed for over 300 bowhead whales to be added to the calalog. For each individual, where available, it includes their number in the catalog, sex, name, year and area of ​​first sighting, as well as full-body images, individual tail images, and identifying features. The catalog allows users to identify each whale by a set of distinctive external features and track their migrations in the waters of the Sea of ​​Okhotsk. This publication will also facilitate the collection of data on the status of the population and the challenges whales face, such as entanglement in fishing gear. "The catalog can become a publically accessible tool for comparing data collected from travelers, volunteers, and tour company employees. There are several of us on the team, and the tourist flow is several hundred. It might not be easy to identify a specific whale without experience, but we hope that the release of this catalog will spur interest in our work. And with our help, people will begin to get to know whales better – in every sense of the word," notes project manager Milena Morozova. "The project to study and preserve the Okhotsk Sea whales is a key one for the Nature and People Foundation," says Irina Onufrenya, head of the Foundation's wildlife conservation program. "We see how, thanks to the support and participation of many organizations and our supporters, it is developing and producing concrete, tangible results. This catalog is another step toward preserving these unique marine giants." The publication also contains comprehensive information on the project's history, the species' current status, and the main threats to its existence. Particular attention is given to recommendations for data collection by volunteers, emphasizing the open nature of the project and its focus on engaging the general public in conservation. The catalog can be accessed via this link. Related materials: Nature and People: "Russia's first catalog of bowhead whales in the Sea of ​​Okhotsk population published" RAS: ""Bowhead Whales of the Sea of ​​Okhotsk." A catalog of individual specimens for 2020-2025 has been published" Vedomosti: "Russian scientists have created a catalog of bowhead whales in the Sea of ​​Okhotsk population" Far East 2030: "Russia has published the first catalog of bowhead whales in the Sea of ​​Okhotsk" Rambler: "Russia has published the first catalog of bowhead whales in the Sea of ​​Okhotsk population" Kamchatka.Liv: "Every third whale is scarred: the consequences of fishing in the Sea of ​​Okhotsk" Zen: "Russian scientists have created a catalog of bowhead whales in the Sea of ​​Okhotsk population" Mammals of Russia: "Bowhead Whales of the Sea of ​​Okhotsk" Russian Traveler: "In Russia "Passports" were assigned to all bowhead whales in the Sea of ​​Okhotsk." Nauka.rf: "A catalog of bowhead whales from the Sea of ​​Okhotsk population was created in Russia." Magadanskaya Pravda: "A catalog of endangered bowhead whales was created by researchers from the Sea of ​​Okhotsk." KF Aktiv: "A catalog of bowhead whales from the Sea of ​​Okhotsk population was created in Russia | Science News." My Planet: "Russian biologists issued 'passports' to all bowhead whales." My Biosphere: "Whales of the Sea of ​​Okhotsk received 'passports'." Captains' World: "Whales of the Sea of ​​Okhotsk were given names and a dossier was compiled"

Climate change during the late Pleistocene and Holocene profoundly impacted the demographic characteristics of many species. Small mammals, especially rodents, provide a good model for studying such questions due to their high population sizes and high environmental sensitivity. One of the most suitable subjects is the root vole, Alexandromys oeconomus, a species of the order Rodentia, whose range has varied widely in the past and present throughout the Holarctic region. An international team of authors, including Svetlana Pavlova, PhD, from the A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences (IEE RAS), used ancient DNA samples isolated from the molars of fossil tundra voles from the late Pleistocene and Holocene to understand the evolutionary history and reconstruct the phylogeography of this widespread rodent species. The scientists identified 12 major genetic lineages within the species, including extinct lineages, highlighting the extensive historical variability of A. oeconomus (Fig. 1). Fig. 1. Distribution of Alexandromys oeconomus specimens assigned to groups identified in the phylogenetic analysis and marked with colors and letters. The red dotted area represents the current distribution of the species based on data from the IUCN Red List (www.iucnredlist.org). An important result was that climate change led to repeated eastward and westward expansions of lineages, as well as the extinction and replacement of individual lineages (Fig. 2). Thus, it was found that, having originated in Central/Western Asia, the root vole migrated to Europe approximately 110,000 years ago and diversified into several lineages. Two return migrations from Central Asia to Northeast Asia occurred approximately 70,000 and 16,000 years ago, preceding the colonization of North America approximately 11,500 years ago. Europe also experienced intense population changes, with subsequent migrations to Western Asia. Fennoscandia was colonized three times after 15,000 years, via two different routes. Fig. 2. Probable phylogeographic relationships and potential directions of migration of genetic lineages of Alexandromys oeconomus in the selected periods. All of these migrations were linked to climate change, with populations increasing during warming periods and decreasing during cooling periods, most noticeably during the Last Glacial Maximum. "This study sheds light on the evolutionary history of the studied rodent species (A. oeconomus), highlighting the complex interactions between geographic distribution, climate, and genetic diversity. These results are important for understanding past population dynamics and the adaptation of root voles in response to changing environmental conditions," said Svetlana Pavlova. The article was published in the Zoological Journal of the Linnean Society (Q1). Related materials: Science.Mail: "Ancient DNA reveals root vole migrations"

Evgeny Vladislavovich Esin, Head of the Laboratory of Lower Vertebrate Ecology and Doctor of Biological Sciences, was elected professor of the Russian Academy of Sciences on December 23, 2025. Congratulations to Evgeny Vladislavovich on his well-deserved title!

Dear colleagues and dear friends! We sincerely congratulate you on the upcoming New Year! We wish you happiness, health, the fulfillment of your plans, exciting expeditions and research, and the strengthening of our Institute's scientific potential! Best wishes for the New Year!

Photo: Participants of the conference at the Faculty of Veterinary Medicine, Central Mindanao University From November 25 to December 10, 2025, researchers from the A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences (IEE RAS) conducted a zoological expedition to the Philippine island of Mindanao, supported by a grant from the Ministry of Science and Higher Education of the Russian Federation. Together with colleagues from Central Mindanao University, a field school was organized for local students. The expedition included a group of specialists in small mammals (primarily bats, rodents, and insectivores), as well as related endo- and ectoparasites. As part of the educational program, the team held open lectures, practical classes, and a field school, sharing their experiences in biodiversity conservation, taxonomy, and research within the One Health framework. During the field school, students learned practical methods for studying wildlife. Photo: Closure of the Central Mindanao University Field School The expedition focused on members of the order Chiroptera — both fruit-eating and insectivorous bats. The work took place in Bukidnon Province, and captures were made in various habitats, both natural and anthropogenically transformed. Sites included the slope of the extinct Musuan volcano, the university campus, and the southeastern part of the Kitanglad Mountain Range National Park. Photo: Identification of insectivorous bats during practical training at a field school in Kitanglad Mountain Range National Park In addition to bats from the families Pteropodidae, Vespertilionidae, and Hipposideridae, several specimens of terrestrial mammal species endemic to the Philippines were captured: the Phillippine forest rat (Rattus everetti) and the Philippine tree shrew (Tupaia everetti), as well as a widely distributed synanthropic species, the Asian house shrew (Suncus murinus). The material collected during the expedition will be used for molecular genetic, helminthological, and virological studies, as well as karyological analysis, to clarify the composition of the fauna and identify potential hidden biodiversity of ecto- and endoparasites and their hosts. The work was carried out within the framework of the grant of the Ministry of Science and Higher Education of the Russian Federation No. 075-15-2025-654 dated August 21, 2025.

The monograph by renowned Russian ornithologist and Doctor of Biological Sciences E.V. Rogacheva, "Birds of Taimyr and Adjacent Territories. Volume I. Anseriformes. Part 2. Ducks," is a reference and information publication that presents a summary of currently (2022) available data—including unpublished data—on the distribution and biology of birds on the Taimyr Peninsula and adjacent territories. Part II of Volume I includes twenty-four species essays, which have a uniform structure and include information on the distribution, breeding range, habitats, reproduction, molting, diet, migrations, wintering, abundance, conservation, and use of each species. Within each subsection, the material is organized by subregion: the Arctic coast and islands, the Yenisei Gulf and the lower reaches of the Yenisei, Western Taimyr, Central Taimyr, Eastern Taimyr, the Putorana Plateau, etc. At the end of the second part, a list of references is provided, general for the entire first volume. The second volume presents a summary of currently (2022) available data, including unpublished data, on the distribution and biology of birds on the Taimyr Peninsula and adjacent territories. The second volume brings together 124 species essays, which are subdivided in a similar fashion: information on the distribution, breeding range, habitats, reproduction, molting, feeding, migration, wintering, abundance, conservation, and use of each species. These monographs are intended for ornithologists. You can download Volume I, Part 2, at this link. You can download Volume II at this link.

Photo: Head of the Cabinet of Molecular Diagnostics of the IPEE RAS M.V. Kholodova. The largest scientific and practical conference, "GENETICS 2025," was held in Moscow from November 5–7, 2025, with the participation of leading Russian and international specialists. The conference announcement was previously sent out by the organizers on behalf of the event's initiator, the N.I. Vavilov Institute of General Genetics (IGG RAS), and was advertised on our institute's website. Researchers from the A.N. Severtsov Institute of Ecology and Evolution (IEE RAS) participated in this significant event, dedicated to important dates in the history of genetics. The year 2025 marks a litany of anniversaries, including the 125th anniversary of genetics itself, as well as the anniversaries of classic Russian and international figures from the formative years of Russian genetic science: the 145th anniversary of Sergei Chetverikov, the 125th anniversary of Nikolai Timofeev-Resovsky, the 125th anniversary of Feodosy Dobzhansky, the 135th anniversary of Hermann Möller, and the 170th anniversary of Ivan Michurin. The event took place in Moscow, in the congress hall of the Radisson Slavyanskaya Hotel. The conference was attended by 1,720 people, including 1,201 in person and 519 online—scientists from two dozen countries and participants from 81 Russian cities. Photo: Specialists in molecular genetic methods for studying mammals E.D. Zemlemerova (Laboratory of Mammalian Microevolution, IEE RAS) and A.A. Bannikova (Moscow State University). Russian specialists presented a wide range of modern research areas, ranging from the structural foundations of genetics, epigenetics, and medical and agricultural genetics to paleo- and historical genetics, behavioral genetics, genome editing, DNA identification in forensics, and bioinformatics. The objects of genetic study are also diverse, from molecular structures to organisms, populations, and species. In particular, the official post-release of the event highlighted key trends in the study of the genetics of natural plant and animal populations, opening new avenues for understanding the processes of genetic variation occurring in nature, including hybridization and introgression, which lead to network evolution and transform the concept of species. Photo: Specialist in molecular cytogenetic analysis S.V. Pavlova (Laboratory of Population Ecology, IEE RAS). The session moderators and speakers included renowned geneticists and heads of research institutions conducting genetic research. From the A. N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences: Director Sergei Valerievich Naidenko, Corresponding Member of the Russian Academy of Sciences, Honorary Chair of Session 21, "Behavioral Genetics"; and Marina Vladimirovna Kholodova, Doctor of Biological Sciences and Senior Researcher, presented at Session 3, "Population and Ecological Genetics." Research topics from the Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, were presented at Session 2, "Ancient DNA. Paleo- and Historical Genetics" (E. D. Zemlemerova, V. A. Komarova, A. A. Martynov, L. A. Lavrenchenko) and Session 9, "Evolutionary Genetics" (N. Sh. Bulatova, S. V. Pavlova). Upon completion, the event was described as unprecedented in its breadth and scope of participation. Even non-specialists could register, listen to presentations, and ask questions, either in person or online, and completely free of charge. According to IOGEN Director A.V. Misyurin, Doctor of Biological Sciences, the founder and first director of the Academic Institute of Genetics, Academician Nikolai Ivanovich Vavilov, "loved holding such congresses and was an active participant in them. We would like to revive this tradition and hold such conferences every year." At one time, the next International Genetics Congress, scheduled for 1937 in Moscow under the chairmanship of N.I. Vavilov, could have become a shining example of cutting-edge science. This did not happen. The USSR was in the midst of an antigenetic campaign. Only in 1939 did the congress take place in Edinburgh, Scotland, without Vavilov. In 1940, the scientist was arrested during an expedition and died in prison. The history of Russian genetics was not interrupted by irreparable losses and has not been forgotten, as evidenced by both the composition of the participants and the program of the "Genetics-2025" conference. Individual genetic research began as early as the first decade of our institute's history, when it was known as the Institute of Evolutionary Morphology (IEM USSR Academy of Sciences), under the directorship of Academician I.I. Shmalhausen (1936–1948). The academician's major work, "Factors of Evolution," written during evacuation and published immediately after the end of the Great Patriotic War, was highly regarded by the founders of the theory of evolutionary synthesis as a work unrivaled in the comprehensiveness of its genetic content. For his work in genetics, like Vavilov before him, the author was persecuted during the Lysenko era. The application of laboratory-based genetic methods was further developed at the Institute of Evolutionary Morphology and Ecology of Animals (IEMEA USSR Academy of Sciences, now IEE RAS) in the 1970s, when the laboratory, organized in 1950 by Professor S.N. Bogolyubsky, was headed by his successor, Doctor of Biological Sciences V.N. Orlov. The modern Laboratory of Mammalian Microevolution, headed by Doctor of Biological Sciences L.A. Lavrenchenko, celebrated its glorious 75th anniversary this year by participating, along with other institute departments, in the work of the anniversary Conference Genetics-2025 (see photos from the conference photo gallery).

This monograph by E.I. Ilyashenko and V.Yu. Ilyashenko traces the history of crane taxonomy, from order to subspecies, and the use of nomenclature from Aristotle to the early 2000s. A direct examination of publications dating back to the 16th century allowed us to identify errors in the sources citing them. The book is illustrated with portraits of the cited authors and images of the cranes described, as well as photographs of all crane species and subspecies. This book is intended for general zoologists and specialists in the history and modern taxonomy of birds. The monograph can be downloaded from this link.

The Joint Russian-Vietnamese Tropical Research and Technology Center wishes the IEE RAS Directorate and all its staff a Happy New Year! The Center expresses its gratitude for the ongoing active support provided by the A.N. Severtsov Institute of Ecology and Evolution to the Russian-Vietnamese Tropical Center, as well as for the fruitful collaboration that enabled significant scientific results to be achieved over the past year. May the collaboration between the IEE RAS and the Center continue to strengthen and expand in 2026, opening up new opportunities for scientists from both countries to conduct joint research. May the coming year bring the successful implementation of all scientific plans and projects. On New Year's Eve, the Center extends its best wishes to all IEE RAS staff and their families for good health, happiness, and success in their responsible work.