Altai-Sayan Research Articles

Modern spore-pollen spectra of the Altai-Sayan region, their relationship with climate and transfer functions for palaeoclimate reconstructions

Modern spore-pollen spectra of the Altai-Sayan region, their relationship with climate and transfer functions for palaeoclimate reconstructions

ISOTOPE COMPOSITION OF Pb AND Nd OF THE LATE NEOPROTEROZOIC–EARLY PALEOZOIC GRANITOIDS IN EASTERN TUVA (Case study of the Kaa-Khem batholith)

We present the results of Nd and Pb isotope studies of late Neoproterozoic–early Paleozoic granitoids of the Kaa-Khem batholith, which formed in different geodynamic settings within the early Caledonian structures of Eastern Tuva (Altai–Sayan sialic area). Based on the obtained isotope data, we assess the role of different source materials in the formation of melts for these granitoids and compare these rocks with coeval granitoids from the Lake Zone of Mongolia. The plagiogranitoid associations of the island arc stage of the Kaa-Khem batholith formation (572–562 Ma) are characterized by mantle Nd isotope values. In contrast, the Pb isotope characteristics of these intrusive associations correspond to an upper-crust source formed predominantly by terrigenous sediments. The granitoid associations of the accretion–collision stage of the Kaa-Khem batholith formation (512–450 Ma) have a less radiogenic primary Pb isotope composition as compared with the island arc granitoids. Evidently, during the magma formation at this stage, the relative role of terrigenous material decreased, while the role of depleted mantle material increased. At the same time, the decrease in ɛNd values in the granitoids as compared with the depleted mantle indicates that, along with the upper-mantle component, the role of the lower-crust component increased. These Nd and Pb isotope characteristics of the accretionary granitoids of the Kaa-Khem batholith indicate a significant contribution of the lower-crust source to their formation. This source is the crystalline basement of the Tuva–Mongolian microcontinent. The Pb isotope characteristics of the accretion–collision granitoids of the Kaa-Khem batholith are shifted to the upper-crust compositions relative to those of the Lake Zone granitoids. The reason is that the latter formed predominantly through the transformation of early Caledonian island arc complexes, which were generated with a higher portion of mantle component.

FamilyTreeDNA Group Project Administrator Stockholm, Sweden

Abstract. Several scholars have in the past hypothesized a northward movement of Hunnic contingents which ultimately reached Scandinavia on the basis of archaeological and philological evidence, an event which should be detectable in both ancient and modern DNA if true. Here I report that when analyzing a combination of ancient and modern DNA samples from across Eurasia one can detect a westward movement from the Altai-Sayan region to Europe which ultimately reached southern Sweden, and also accurately date this migration event to the 4th and 5th centuries CE with the help of carbon-14 dating and estimated TMRCAs of certain Y-DNA lineages. It is possible to identify these individuals and groups as Huns by analyzing their Y-chromosomal and autosomal DNA in combination with burial context. The significance and implications of this become clear when looking at the philological evidence which suggests that the Huns had a formative and lasting impact on the development of the peoples, cultures and beliefs of Scandinavia Keywords: Attila, Huns, Scythians, Y-DNA, Xiongnu

Characteristic Ddepth distribution of crustal earthquakes in Southern Siberia

The key parameters of an earthquake are magnitude, epicenter coordinates, and depth. Depth often has a decisive influence on the macroseismic effect of certain earthquakes. In this regard, for example, to assess seismic risk, one should know information on the statistics of earthquake occurrence at certain depths. In this work, catalogs of continental crustal earthquakes in the Southern Siberia are analyzed. The distributions of earthquake depths are approximated by various functions. The Weibull distribution, with a maximum at 8 km, is shown to describe the depth distribution of these crustal earthquakes most accurately. When the western (Altai–Sayan) and eastern (Baikal Rift Zone) parts of the region are considered separately, the Weibull distribution is also preferable. The maximum of the distribution is found to be at 9 km for the Baikal rift zone and at 7 km for the Altai–Sayan zone.

Study of a Polymorphic Variant of the TRPM8 Cold Receptor Gene (rs7593557) in 15 Populations of the Altai-Sayan Region and the Far East

Study of a Polymorphic Variant of the TRPM8 Cold Receptor Gene (rs7593557) in 15 Populations of the Altai-Sayan Region and the Far East

Meso—Cenozoic Exhumation of the Altai-Sayan Region: Constrained by Available Low-Temperature Thermochronology

Meso—Cenozoic Exhumation of the Altai-Sayan Region: Constrained by Available Low-Temperature Thermochronology

Determination of Earthquake Depths Using Data of Cross-Sectional and Areal Deep Seismic Studies in Siberia

Abstract ––Information on the distribution of earthquake hypocenters for many seismically active zones of Siberia remains insufficient, which is associated with sparse networks of seismological observations. The paper presents the results of determining the earthquake depths in several seismogenic areas in the Altai-Sayan region, Cisbaikalia, Transbaikalia, and Yakutia using the travel time of longitudinal refracted waves from the Mohorovičič discontinuity (Pn waves) from earthquakes and the recently obtained information about the deep structure of these regions. The depth determination algorithm is tested using data from aftershocks of large earthquakes occurring in Tuva in 2011 and 2012 (ML = 6.7 and 6.8), recorded both by the regional seismological network and by a local group of seismic stations. Different methods are applied to reveal that some aftershock depths have a close match, including those for the main shocks – the Tuva-1 and Tuva-2 earthquakes. Another good match of earthquake depths is obtained using Рn waves with materials from regional and detailed studies of the Baikal branch of the Geophysical Survey of the Russian Academy of Sciences in the Muyakan activation site in the Baikal rift zone. The resulting data complement the information on the hypocenter of the main shock and confirm the change of the Muyakan activation cluster from large depths to shallow ones since the onset of activation in 2014. New information on the earthquake depths using Рn waves is obtained in Yakutia along the border of the largest Eurasian and Okhotsk tectonic plates. It is revealed that they decrease to 6–12 km as compared to higher depths of 20–30 km in adjacent areas. The resulting series of new information on the distribution of earthquake hypocenters using Рn waves is extremely important mostly because it indicates the possibility of identifying and redefining earthquake hypocenters using previous seismological observations in seismically active zones of Siberia.

Сartographic models of soil temperature fields in the steppe battles of Khakassia and Tuva based on joint analysis of temperature monitoring ground and satellite data

The aim of the study was to justify the possibility of using quantitative characteristics of the temperature regime of soils obtained by a joint analysis of ground-based and satellite monitoring to create cartographic models of typological units of soil-bioclimatic zonation of the Khakassia and Tuva steppe basins. Location and time of the study. The development of methodology for identifying the temperature fields boundaries was carried out in 2019-2022, using as a case example the soil cover typological units in the Altai-Sayan region, including the diversity of steppes of the Chulym-Yenisei and Minusinsk troughs, the Turan-Uyuk, Central Tuva, and Ubsu-Nur basins. Key areas were selected taking into account the principles of landscape zoning, which make it possible to recognize, classify and map landscape-differentiating factors, landscape components, the regional landscape structure in their entirety and its dynamic features. Methods. Ground-based automated monitoring of air and soil was performed using specialized temperature recorders DS-1921G “Thermochron”, taking into account indicators reflecting the genetic unity of climate types in the Altai-Sayan region. To carry out retrospective analysis, statistical processing and visualization of MODIS data, a software and algorithmic toolkit created by the Institute of Computational Technology of the Siberian Branch of the Russian Academy of Sciences (Novosibirsk) was used: the software is based on a new technology for accessing the satellite data archive, implemented using the PostgreSQL DBMS with an additional module, designed for direct access to the file data archive without the need to first copy and convert the data format for the DBMS. Results. Based on a joint analysis of quantitative indicators of the air and soil temperature regimes, obtained using ground-based automated measuring systems and satellite data, a series of cartographic models were constructed: the latter reflect the temperature fields characteristics of typological units of soil-bioclimatic zoning of the Altai-Sayan region. The interpretation of the identification of typological units of the soil cover structure performed on the basis of a statistical analysis of the combination of boundaries and information content of the contours of the soil cover and the boundaries of temperature fields (day and night temperatures, as well as the difference in temperatures of two compiled series, calculated over a 16-year period). The novelty of the approach is based on the fact that cartographic models of temperature fields, constructed on the basis of quantitative temperature indicators, have information content sufficient for establishing relationships between the temperature regime and other characteristics of natural environmental objects, contributing to solving the problem of identifying and typologizing soil-ecological boundaries. Conclusions. Cartographic models of temperature fields obtained as a result of a joint analysis of ground-based and satellite data are sufficiently informative regarding the energy of soil-forming processes and can be used to assess soil thermal conditions in the inaccessible and hence poorly studied areas of the Altai-Sayan region.

SEISMICITY of the ALTAI and SAYAN region in 2018–2019

The seismicity of the Altai-Sayan region in 2018–2019 is considered. The stationary seismic network within the reporting period consisted of 55 stations. Upgrading the recording equipment and retrofitting the stations with strong motion sensors was continued. In addition to the stationary network, five local networks functioned in the region. One of them investigated the seismic process and accumulated data for constructing the Moho boundary using the method of receiving functions in the Altai Republic, the other four were focused on the study of technogenic seismicity in the area of coal minings of the Kemerovo and Novosibirsk regions. During the reporting period, 15405 earthquakes were registered in the region, 52 % of them occurred in the Chui-Kurai zone of the Altai Mountains, for which a brief description of seismicity is given separately. The total seismic energy released in earthquake foci was 2.191012 J in 2018 and 1.171013 J in 2019. The slope of the linear part of the earthquake recurrence chart for 2018–2019 has not undergone significant changes compared to previous reporting periods. The largest earthquake on the territory of the Altai-Sayan region for the reporting period (ML=6.2) occurred on February 1, 2019 at 21h54m in China, 70 km south of the Zaisan lake

Dissolved Carbon Concentrations and Emission Fluxes in Rivers and Lakes of Central Asia (Sayan–Altai Mountain Region, Tyva)

The carbon (C) cycle in inland waters, including carbon concentrations in and carbon dioxide (CO2) emissions from water surfaces, are at the forefront of biogeochemical studies, especially in regions strongly impacted by ongoing climate change. Towards a better understanding of C storage, transport and emission in Central Asian mountain regions, an area of knowledge that has been extremely poorly studied until now, here, we carried out systematic measurements of dissolved C and CO2 emissions in rivers and lakes located along a macrotransect of various natural landscapes in the Sayan–Altai mountain region, from the high mountains of the Western Sayan in the northwest of Tyva to the arid (dry) steppes and semideserts in the intermountain basins in the southeast of Tyva on the border with Mongolia. New data on major hydrochemical parameters and CO2 fluxes (fCO2) gathered by floating chambers and dissolved organic and inorganic carbon (DOC and DIC, respectively) concentrations collected over the four main hydrological seasons allowed us to assess the current C biogeochemical status of these water bodies in order to judge possible future changes under climate warming. We further tested the impact of permafrost, river watershed size, lake area and climate parameters as well as ‘internal’ biogeochemical drivers (pH, mineralization, organic matter quality and bacterial population) on CO2 concentration and emissions in lakes and rivers of this region and compared them with available data from other subarctic and mountain settings. We found strong environmental control of the CO2 pattern in the studied water bodies, with thermokarst lakes being drastically different from other lakes. In freshwater lakes, pCO2 negatively correlated with O2, whereas the water temperature exerted a positive impact on pCO2 in large rivers. Overall, the large complexity of counteracting external and internal drivers of CO2 exchange between the water surfaces and the atmosphere (CO2-rich underground DIC influx and lateral soil and subsurface water; CO2 production in the water column due to dissolved and particulate OC biodegradation; CO2 uptake by aquatic biota) precluded establishing simple causalities between a single environmental parameter and the fCO2 of rivers and lakes. The season-averaged CO2 emission flux from the rivers of Tyva measured in this study was comparable, with some uncertainty, to the C uptake fluxes from terrestrial ecosystems of the region, which were assessed in other works.

Geological and Isotope-Geochemical Indicators of Early Devonian Plume–Lithosphere Interactions in the Southwestern Framing of the Siberian Craton: Data Synthesis for Magmatic Associations of the Altai–Sayan Rift System

Abstract —The Early Devonian Altai–Sayan rift system (ASRS) has spread to the structures of East and West Sayan, Kuznetsk Alatau, and Mongolian Altay. Its largest fragments are the Tuva, Delyun–Yustyd, Kan, Agul, and Minusa basins as well as depressions in north-western Mongolia. The paper summarizes the geologic, geochemical, and Sr–Nd isotope characteristics of the ASRS mafic rocks represented by nappes of moderately alkaline and alkali basalts and their subvolcanic and intrusive rock analogues. They are present in all magmatic associations and are divided into low-Ti (TiO2 = 0.2–2.2 wt.%) and high-Ti (TiO2 = 2.2–4.3 wt.%) subgroups. These rocks are characterized by wide variations in Sr isotope characteristics (εSr(T) = –16 to +30). High-Ti mafic rocks are common at the southern segment of the ASRS; they show a weak positive Ta–Nb anomaly (La/Nb = 0.8–1.1) and are relatively enriched in LREE ((La/Yb)N = 6–14) and radiogenic Nd (εNd(T) = 3.8–8.7). Low-Ti varieties are confined to the northwestern segment of the ASRS; they are enriched in Ba but depleted in Th, U, Nb, Ta (La/Nb = 1.2–2.2), Zr, Hf, LREE ((La/Yb)N = 3–7), and radiogenic Nd (εNd(T) = 2.0–6.0). Taking into account the existence of different terranes, which were combined in the structure of the Altai–Sayan folded area during accretion (ca. 500–480 Ma), we propose a model suggesting different environments of magma formation at the southern and northwestern segments of the ASRS and the relationship of magmatism with a mantle plume within the ASRS. In composition the plume corresponds to the sources of high-Ti magmas. The effect of the melted lithospheric mantle of different compositions beneath different groups of terranes led to the observed isotope-geochemical heterogeneity of mafic rocks within the ASRS, in particular, the absence of high-Ti mafic rocks from the Minusa basin.

High-resolution ecosystem changes pacing the millennial climate variability at the Middle to Upper Palaeolithic transition in NE-Italy

Observation of high-resolution terrestrial palaeoecological series can decipher relationships between past climatic transitions, their effects on ecosystems and wildfire cyclicity. Here we present a new radiocarbon dated record from Lake Fimon (NE-Italy) covering the 60–27 ka interval. Palynological, charcoal fragments and sediment lithology analysis were carried out at centennial to sub-centennial resolutions. Identification of the best modern analogues for MIS 3 ecosystems further enabled to thoroughly reconstruct structural changes in the vegetation through time. This series also represents an “off-site” reference record for chronologically well-constrained Palaeolithic sites documenting Neanderthal and Homo sapiens occupations within the same region. Neanderthals lived in a mosaic of grasslands and woodlands, composed of a mixture of boreal and broad-leaved temperate trees analogous to those of the modern Central-Eastern Europe, the Southern Urals and central-southern Siberia. Dry and other grassland types expanded steadily from 44 to 43 ka and peaked between 42 and 39 ka, i.e., about the same time when Sapiens reached this region. This vegetation, which finds very few reliable modern analogues in the adopted Eurasian calibration set, led to the expansion of ecosystems able to sustain large herds of herbivores. During 39–27 ka, the landscape was covered by steppe, desert-steppe and open dry boreal forests similar to those of the modern Altai-Sayan region. Both Neanderthal and Sapiens lived in contexts of expanded fire-prone ecosystems modulated by the high-frequency climatic cycles of MIS 3.

Relationship of the gene pool of the Khants with the peoples of Western Siberia, Cis-Urals and the Altai-Sayan Region according to the data on the polymorphism of autosomic locus and the Y-chromosome.

Khanty are indigenous Siberian people living on the territory of Western Siberia, mainly on the territory of the Khanty-Mansiysk and Yamalo-Nenets Autonomous Okrugs. The present study is aimed at a comprehensive analysis of the structure of the Khanty gene pool and their comparison with other populations of the indigenous population of Southern and Western Siberia. To address the issues of genetic proximity of the Khanty with other indigenous peoples, we performed genotyping of a wide genomic set of autosomal markers using high-density biochips, as well as an expanded set of SNP and STR markers of the Y-chromosome in various ethnic groups: Khakas, Tuvans, Southern Altaians, Siberian Tatars, Chulyms (Turkic language family) and Kets (Yeniseian language family). The structure of the gene pool of the Khanty and other West Siberian and South Siberian populations was studied using a genome-wide panel of autosomal single nucleotide polymorphic markers and Y-chromosome markers. The results of the analysis of autosomal SNPs frequencies by various methods, the similarities in the composition of the Y-chromosome haplogroups and YSTR haplotypes indicate that the Khanty gene pool is quite specific. When analyzing autosomal SNPs, the Ugrian genetic component completely dominates in both samples (up to 99-100 %). The samples of the Khanty showed the maximum match in IBD blocks with each other, with a sample of the Kets, Chulyms, Tuvans, Tomsk Tatars, Khakas, Kachins, and Southern Altaians. The degree of coincidence of IBD blocks between the Khanty, Kets, and Tomsk Tatars is consistent with the results of the distribution of allele frequencies and common genetic components in these populations. According to the composition of the Y-chromosome haplogroups, the two samples of the Khanty differ significantly from each other. A detailed phylogenetic analysis of various Y-chromosome haplogroups made it possible to describe and clarify the differences in the phylogeny and structure of individual ethnospecific sublines, to determine their relationship, traces of population expansion in the Khanty gene pool. Variants of different haplogroups of the Y-chromosome in the Khanty, Khakas and Tuvans go back to their common ancestral lines. The results of a comparative analysis of male samples indicate a close genetic relationship between the Khanty and Nenets, Komi, Udmurts and Kets. The specificity of haplotypes, the discovery of various terminal SNPs confirms that the Khanty did not come into contact with other ethnic groups for a long time, except for the Nenets, which included many Khanty clans.

Structure and origin of Tuvan gene pool according to autosome SNP and Y-chromosome haplogroups.

Tuvans are one of the most compactly living peoples of Southern Siberia, settled mainly in the territory of Tuva. The gene pool of the Tuvans is quite isolated, due to endogamy and a very low frequency of interethnic marriages. The structure of the gene pool of the Tuvans and other Siberian populations was studied using a genome-wide panel of autosomal single nucleotide polymorphic markers and Y-chromosome markers. The results of the analysis of the frequencies of autosomal SNPs by various methods, the similarities in the composition of the Y-chromosome haplogroups and YSTR haplotypes show that the gene pool of the Tuvans is very heterogeneous in terms of the composition of genetic components. It includes the ancient autochthonous Yeniseian component, which dominates among the Chulym Turks and Kets, the East Siberian component, which prevails among the Yakuts and Evenks, and the Far Eastern component, the frequency of which is maximum among the Nivkhs and Udeges. Analysis of the composition of IBD-blocks on autosomes shows the maximum genetic relationship of the Tuvans with the Southern Altaians, Khakas and Shors, who were formed during the settlement of the Turkic groups of populations on the territory of the Altai-Sayan region. A very diverse composition of the Tuvan gene pool is shown for various sublines of Y-chromosomal haplogroups, most of which show strong ethnic specificity. Phylogenetic analysis of individual Y-chromosome haplogroups demonstrates the maximum proximity of the gene pool of the Tuvans with the Altaians, Khakas and Shors. Differences in frequencies of Y-chromosome haplogroups between the Todzhans and Tuvans and a change in the frequencies of haplogroups from south to north associated with the East Asian component were found. The majority of the most frequent Y-chromosome haplogroups in the Tuvans demonstrate the founder effect, the formation age of which is fully consistent with the data on their ethnogenesis.

Linkage between the India–Asia collision and far-field reactivation of the Altai mountains

The present northwest-trending Altai mountains, as far as ∼2000 km north of the Indian–Asian collision front, are dominated by a transpressional strike-slip fault system, and are generally considered as one of distant tectonic effects of the ongoing India–Asia collision. However, the Cenozoic reactivation of the Altai and its linkage with the tectonic evolution of the Tibet plateau remain mechanically challenging. Here, we constructed large-scale 2D numerical models with inherited lithospheric heterogeneities from India to Altai representing the onset of the India–Asia collision. The sensitivity of model results to variable thermo-mechanical and geometric properties of the orogen-like Tibet and Altai as well as variable thermal state of the craton-like India and Junggar reveals that both the particular lithospheric architecture of western Tibet and basement structural inheritance of central Asia regulate the long-distance deformation propagation from the India–Asia plate boundary to the Altai–Sayan region. The model results indicate that the direct collision of the underthrusting Indian lithosphere with the rigid Tarim block beneath western Tibet plays a dominant role in the ultra-long-distance deformation propagation to central Asia. As less-deformed rigid blocks, the Tarim and Junggar basins with Precambrian basements serve as secondary indenters that transfer the compressive stresses extensively to the Altai–Sayan region. Constrained by substantial surface geology and geophysical observations, this numerical study recognizes the linkage between the evolving lithospheric structure of western Tibet with the northward younging trend of reactivation of the orogenic belts in central Asia. By means of the rigid Indian–Tarim lithospheric mantle collision, the plate-convergence stress can be effectively transmitted through Tarim to Tian Shan and subsequently through Junggar to Altai, leading to successive reactivation of the Tian Shan and Altai mountains. The locations of reactivation are determined by the inherited structural zones of lithospheric weakness that formed during the Paleozoic assembly of the Central Asian Orogenic Belt.

Fault systems in multiply deformed regions of Eurasia

We have studied the orogenic fragile deformation of the upper Earth's crust of several areas of the Eurasian continent, where deformations have occurred many times -- in the Tian Shan and Altai-Sayan regions of the Central Asian Paleozoic Fold Belt and in the Baltic region in the Fennoscandian Shield (East European Platform). Our processing of data on the trends of more than 4000 faults allows us to identify fault systems and relationships among these fault systems. Changes in the intensity and kinematics of the activity of fault systems in different epochs of deformation of regions are revealed. In the Tien Shan and Altai-Sayan regions, fault movements occurred during Early Paleozoic, Late Paleozoic and Late Cenozoic orogenies. No new fault systems appeared in the Late Cenozoic deformation in the Tien Shan, where only movement along Paleozoic faults that were suitably oriented occurred. In the Altai-Sayan region, we identify the Late Paleozoic associations of fault systems that activated in the recent epoch and the association of fault systems created in the Late Cenozoic. The Fennoscandian Shield shows different fault kinematics in four Early Proterozoic deformational periods. Our method of analysis of associations of fault systems contributes to a~systematization of data on multi-stage deformation in the upper crust of these regions.

Salair–Gornaya Shoria Junction (Northwestern Central Asian Orogenic Belt): Deep Structure and Tectonics from Magnetotelluric Data

Abstract —The Salair fold-thrust orogenic belt (Salair orogen, Salair) is located in the northwestern Altai–Sayan fold area within the Central Asian Orogenic Belt. The Salair orogen is an allochthon overriding the Kuznetsk Basin on a system of imbricate thrusts. The southern flank of the Salair thrust system is tectonically juxtaposed against the Gornaya Shoria terrane which differs markedly from Salair in its geological setting. The Salair and Gornaya Shoria terranes are separated by the Nenya-Chumysh Basin, a deep Mesozoic trough. The Salair orogen is composed of Cambrian–Early Ordovician island arc volcanic and sedimentary rocks, widespread garnet amphibolites and gneisses of the Angurep complex in its southern flank, and the Shalap subduction-related melange in the Alambai ophiolite suture. The southern Salair orogen and its junction with Gornaya Shoria have been imaged down to the lower crust by magnetotelluric (MT) soundings, which is an efficient tool for investigating the deep structure and tectonic history of orogenic areas. The MT surveys were performed at 25 stations on a 120 km long profile. MT data revealed an up to 70 km wide low-resistivity zone (a conductor) traceable till a depth of 20 km between the Salair and Gornaya Shoria terranes. The low-resistivity zone has a complex structure with its outer and interior boundaries dipping almost vertically. The conductor lies under several major geological structures: the Shalap melange, the Nenya-Chumysh Basin, and the NE trending Altai–Salair right-lateral strike-slip fault. The Altai–Salair fault, along which the Salair allochthon was displaced relative to Gorny Altai and Gornaya Shoria, joins the Salair system of imbricate thrusts. The Nenya-Chumysh Basin at the Salair–Gornaya Shoria junction is a deep trough having an asymmetric transversal profile with a steep western side and a shallower-dipping stepped eastern side. The southeastern flank of the basin is a wide area of thin sediments over the Paleozoic basement dipping gently in the northwestern direction. The revealed deep structure of the Nenya-Chumysh trough is consistent with its tectonic model implying an Early Cretaceous basin superposed over an early Jurassic pull-apart basin. Early Mesozoic motions on major faults is a regional-scale phenomenon known from many areas of southern West Siberia.

Современный статус балобана в России и в Казахстане

Современный статус балобана в России и в Казахстане

«Птицы и ЛЭП» в России: наследие СССР, современные достижения и вопросы

«Птицы и ЛЭП» в России: наследие СССР, современные достижения и вопросы

Разработка морфометрической формулы для полевого определения пола птенцов степного орла (Aquila nipalensis) в Алтае-Саянском регионе

Rapid sex determination of Steppe Eagle (Aquila nipalensis) nestlings without laboratory diagnostics is necessary for a variety of tasks. When working directly on a nest, it is important to know the sex of nestlings during population monitoring, ringing and tagging with GPS transmitters. Sex determination is also necessary when working with sick and injured birds, in rehabilitation centers, which do not always have the opportunity and time for genetic analysis. Experienced ornithologists in most cases can quite accurately determine the sex of nestling by eye, but this does not always work, and not all researchers have sufficient experience. The Steppe Eagle has a noticeable sexual dimorphism in size, which is well manifested even in 45-day-old nestlings. However, the size ranges of females and males overlap greatly, so one cannot reliably determine sex simply by measuring any one part of the bird's body. We have developed morphometric discriminant formulas that allow us to determine with high accuracy the sex of a Steppe Eagle nestlings in Altai-Sayan region, using the size of the tarsus, claws, beak, and tail feathers. The formulas were obtained based on measurements of (n=52) 55–65-dayold nestlings (25 males and 27 females) born in 2019. The nestling sex was determined genetically by amplification of the CHD1 gene intron, which has different length in Z and W sex chromosomes of most bird species. We analyzed relationship between various morphometric characteristics of the nestling and its sex and obtained formulas that correctly determine the sex of 51 out of 52 nestlings in the initial sample and 32 out of 33 nestlings in the test sample (born in 2021). Our discriminant formulas use both direct measurement values and ratios of different measurements to each other. In order to obtain the best formula, we altered the set of variables used and eventually chose several formulas that show the best results. These formulas can be used simultaneously to improve the accuracy of the determination. Despite the fact that the size of the tarsus, claws and beak in 55–65 day old nestlings is already quite stable, and the length of the feathers changes quickly, the formula obtained using the length of the tail gave better results than without using it. Statistical analysis showed that females and males of the Steppe Eagle have the most significant differences in tarsus diameter: it is, on average, larger in females. Differences are already noticeable in 45-day-old nestlings, whose paws almost reach the size of those of an adult bird. Moreover, the longitudinal and transverse tarsus diameters weakly correlate with each other and even more weakly with the sizes of beak, claws, and feathers, but they correlate with sex more than other measurements. This is what makes it possible to determine the sex of nestlings in the nest with a fairly high accuracy. However, analysis of nestlings born in 2022, when the depression of pika population led to a severe shortage of food for the Steppe Eagles, shows that with severe underfeeding and a lack of subcutaneous fat, female tarsus turn out to be abnormally thin, and the formula often incorrectly identifies such nestlings as males. Therefore, we developed a separate formula for determining the sex of nestlings with obvious lack of mass, which in turn less accurately determines the sex of normal nestlings. Thus, when using morphometry to determine sex, it is necessary to take into account the body condition of the nestling. The study was supported by the Basic Research Program FWGZ-2021-0014.