Review: Ruminant heat-stress terminology.

With increasing climate variability, there is a rise in the exposure to, and incidence of, ruminant heat stress (HS), increasing the requirement for focused research. As such, precise terminology is crucial to maintain effective communication and knowledge advancement. Despite this, several key terms are currently defined inconsistently, leading to confusion and misinterpretation. This paper examines the historical and contemporary use of the terms 'resistance', 'tolerance', 'resilience', and 'susceptibility' across various disciplines, revealing significant ambiguities that hinder both research and practice. Through this comprehensive review, we propose new definitions for each term as they are used relating to HS, with a focus on ruminant production. Proposed definitions align with current scientific understanding, providing a robust framework for future research and application. As further research is conducted, we hope these definitions can be improved through the inclusion of quantitative measures which align with these classifications. This present review provides definition clarity for common heat abatement terminology, enabling consistency and from this, progress in the field to ameliorate HS for ruminants.

Population structure and genetic diversity of non-native aoudad populations.

The aoudad (Ammotragus lervia Pallas 1777) is an ungulate species, native to the mountain ranges of North Africa. In the second half of the twentieth century, it was successfully introduced in some European countries, mainly for hunting purposes, i.e. in Croatia, the Czech Republic, Italy, and Spain. We used neutral genetic markers, the mitochondrial DNA control region sequence and microsatellite loci, to characterize and compare genetic diversity and spatial pattern of genetic structure on different timeframes among all European aoudad populations. Four distinct control region haplotypes found in European aoudad populations indicate that the aoudad has been introduced in Europe from multiple genetic sources, with the population in the Sierra Espuña as the only population in which more than one haplotype was detected. The number of detected microsatellite alleles within all populations (< 3.61) and mean proportion of shared alleles within all analysed populations (< 0.55) indicates relatively low genetic variability, as expected for new populations funded by a small number of individuals. In STRUCTURE results with K = 2-4, Croatian and Czech populations cluster in the same genetic cluster, indicating joined origin. Among three populations from Spain, Almeria population shows as genetically distinct from others in results, while other Spanish populations diverge at K = 4. Maintenance of genetic diversity should be included in the management of populations to sustain their viability, specially for small Czech population with high proportion of shared alleles (0.85) and Croatian population that had the smallest estimated effective population size (Ne = 5.4).

An atlas of CNV maps in cattle, goat and sheep.

Copy number variation (CNV) is the most prevalent type of genetic structural variation that has been recognized as an important source of phenotypic variation in humans, animals and plants. However, the mechanisms underlying the evolution of CNVs and their function in natural or artificial selection remain unknown. Here, we generated CNV region (CNVR) datasets which were diverged or shared among cattle, goat, and sheep, including 886 individuals from 171 diverse populations. Using 9 environmental factors for genome-wide association study (GWAS), we identified a series of candidate CNVRs, including genes relating to immunity, tick resistance, multi-drug resistance, and muscle development. The number of CNVRs shared between species is significantly higher than expected (P<0.00001), and these CNVRs may be more persist than the single nucleotide polymorphisms (SNPs) shared between species. We also identified genomic regions under long-term balancing selection and uncovered the potential diversity of the selected CNVRs close to the important functional genes. This study provides the evidence that balancing selection might be more common in mammals than previously considered, and might play an important role in the daily activities of these ruminant species.

Re-evaluation of the "law of constant extinction" for ruminants at different taxonomical scales.

The "law of constant extinction," proposed by Van Valen, states that long and short-lived taxa have equal chances of going extinct. This pattern of age-independent extinction was originally inferred using the fossil record of several different taxa and relied on survivorship curves built from the literal reading of the fossil record. Van Valen's seminal work was mostly done at higher taxonomic levels, hence its prevalence at the species level could not be directly inferred. The surprisingly few subsequent studies done at the species level have challenged the prevalence of age-independent extinction, but those have, for the most part, failed to explicitly incorporate inherent biases of the fossil record. Using a recent Bayesian framework that accounts for several of those biases, including the fact that very short-living lineages might never make to the record itself, we showed that Ruminantia species present age-dependent extinction, where extinction probability decreases with species age. An analysis at the genus level suggested age-independent extinction but further examination suggested that the pattern might be more complex than previously reported by Van Valen. Our results indicate that different taxonomic levels may present different extinction regimes, which could justify the development of new macroevolutionary theory and methods.

Metagenomic analysis of the cow, sheep, reindeer and red deer rumen.

The rumen microbiota comprises a community of microorganisms which specialise in the degradation of complex carbohydrates from plant-based feed. These microbes play a highly important role in ruminant nutrition and could also act as sources of industrially useful enzymes. In this study, we performed a metagenomic analysis of samples taken from the ruminal contents of cow (Bos Taurus), sheep (Ovis aries), reindeer (Rangifer tarandus) and red deer (Cervus elaphus). We constructed 391 metagenome-assembled genomes originating from 16 microbial phyla. We compared our genomes to other publically available microbial genomes and found that they contained 279 novel species. We also found significant differences between the microbiota of different ruminant species in terms of the abundance of microbial taxonomies, carbohydrate-active enzyme genes and KEGG orthologs. We present a dataset of rumen-derived genomes which in combination with other publicly-available rumen genomes can be used as a reference dataset in future metagenomic studies.

Modes of genetic adaptations underlying functional innovations in the rumen.

The rumen is the hallmark organ of ruminants and hosts a diverse ecosystem of microorganisms that facilitates efficient digestion of plant fibers. We analyzed 897 transcriptomes from three Cetartiodactyla lineages: ruminants, camels and cetaceans, as well as data from ruminant comparative genomics and functional assays to explore the genetic basis of rumen functional innovations. We identified genes with relatively high expression in the rumen, of which many appeared to be recruited from other tissues. These genes show functional enrichment in ketone body metabolism, regulation of microbial community, and epithelium absorption, which are the most prominent biological processes involved in rumen innovations. Several modes of genetic change underlying rumen functional innovations were uncovered, including coding mutations, genes newly evolved, and changes of regulatory elements. We validated that the key ketogenesis rate-limiting gene (HMGCS2) with five ruminant-specific mutations was under positive selection and exhibits higher synthesis activity than those of other mammals. Two newly evolved genes (LYZ1 and DEFB1) are resistant to Gram-positive bacteria and thereby may regulate microbial community equilibrium. Furthermore, we confirmed that the changes of regulatory elements accounted for the majority of rumen gene recruitment. These results greatly improve our understanding of rumen evolution and organ evo-devo in general.

Ancient genomes reveal tropical bovid species in the Tibetan Plateau contributed to the prevalence of hunting game until the late Neolithic.

Local wild bovids have been determined to be important prey on the northeastern Tibetan Plateau (NETP), where hunting game was a major subsistence strategy until the late Neolithic, when farming lifestyles dominated in the neighboring Loess Plateau. However, the species affiliation and population ecology of these prehistoric wild bovids in the prehistoric NETP remain unknown. Ancient DNA (aDNA) analysis is highly informative in decoding this puzzle. Here, we applied aDNA analysis to fragmented bovid and rhinoceros specimens dating ∼5,200 y B.P. from the Neolithic site of Shannashuzha located in the marginal area of the NETP. Utilizing both whole genomes and mitochondrial DNA, our results demonstrate that the range of the present-day tropical gaur (Bos gaurus) extended as far north as the margins of the NETP during the late Neolithic from ∼29°N to ∼34°N. Furthermore, comparative analysis with zooarchaeological and paleoclimatic evidence indicated that a high summer temperature in the late Neolithic might have facilitated the northward expansion of tropical animals (at least gaur and Sumatran-like rhinoceros) to the NETP. This enriched the diversity of wildlife, thus providing abundant hunting resources for humans and facilitating the exploration of the Tibetan Plateau as one of the last habitats for hunting game in East Asia.

Deep mitochondrial DNA phylogeographic divergence in the threatened aoudad Ammotragus lervia (Bovidae, Caprini).

The aoudad or Barbary sheep (Ammotragus lervia) is a threatened ungulate emblematic of North Africa, whose population structure and subspecific taxonomy have not been examined genetically. This knowledge is essential and urgently needed to inform ongoing conservation and management efforts. We analysed the mitochondrial cytochrome b gene and four nuclear genes (casein kappa, spectrin beta nonerythrocytic 1, thyroglobulin, thyrotropin subunit beta) for the first phylogeographic survey of the aoudad, and uncovered a deep Mediterranean-Saharan mitochondrial split separating two highly distinct evolutionary lineages. Their level of divergence is greater than or comparable to those observed between several pairs of congeneric species of different caprine genera. The split was estimated to have occurred in the Early Pleistocene, about 1.3 million years ago. None of the four nuclear genes surveyed, chosen because they have been used in phylogeographic and species-level phylogenetic studies of bovids, allowed us to detect, likely due to their slow evolutionary rate, the substantial and geographically coherent subdivision revealed by mitochondrial DNA. This study is evidence and testament to the ability of mitochondrial DNA, probably unrivalled by any other single-locus marker, as an exploratory tool for investigating population genealogy and history and identifying potential evolutionarily significant units for conservation in animals.

The relative importance of phylogeny and habitat in determining the presence and prominence of a granula iridica in hooved mammals.

PURPOSE: To investigate the relationship between phylogeny and amount of shade in a species' habitat regarding the presence or absence of an iridal granula iridica (GI) in a large sample of Artiodactyl and Perissodactyl clades and using online resources. METHODS: The Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW) archives were searched for glass slide material from Artiodactyl (even-toed) and Perissodactyl (odd-toed) ungulates. The slides were examined, and the presence or absence of the GI was noted. The phylogenetic tree of the ungulate species was inferred using TimeTree (http://www.timetree.org), and the habitat data are derived from Animal Diversity Web (https://animaldiversity.org/). We assessed the probability of the presence of GI occurring given the amount of shade in a species' environment using phylogenetic logistic regression. RESULTS: Forty-eight artiodactyl species were able to be evaluated and tabulated. Nine perissodactyl species were able to be evaluated. The phylogenetic logistic regression showed that the probability of GI presence was lower in artiodactyl species that inhabited shaded environments (ßshaded  = -1.774). Arctiodacyl species inhabiting a nonshaded environment were slightly more probable to have the GI present (ßnonshaded  = 0.023), with species inhabitating ambiguously shaded environments having a high probability of GI presence (ßambiguous  = 2.214). CONCLUSIONS: Our results suggest that the GI may be a common morphological feature to shade the pupil in nonshaded environments, and, in its absence, increase the amount of light reaching the retina to improve vision in shaded environments for hooved mammals. Further research on the functional optics of the GI and studies that include additional ungulate species would further elucidate phylogenetic and ecological factors influencing the occurrence of GI in hooved mammals.

Ruminants (Giraffidae and Bovidae) from Kanapoi.

We update here our recent revision of the Kanapoi ruminants and describe recently collected material. We now regard the occurrence of reduncins as doubtful, we revise the identification of a large raphicerin as being more probably Gazella, and we add Gazella cf. janenschi and the Cephalophini to the faunal list. New material of Tragelaphus kyaloi suggests that this species held its head unlike other tragelaphins, and was not an exclusive dedicated browser, but Kanapoi pre-dates the Pliocene change of Sivatherium, Aepyceros, Alcelaphini, and even Tragelaphini toward more grazing diets. Kanapoi shares several ruminant taxa with sites in Ethiopia and Tanzania, attesting to latitudinal exchanges.

Taxonomic status of Chinese blue sheep (Pseudois nayaur): new evidence of a distinct subspecies.

The blue sheep is an endemic species to the Qinghai-Tibet Plateau and surrounding regions. It has been regarded as having 2 subspecies: Pseudois nayaur nayaur and P. n. szechuanensis. However, such a classification remains controversial. Herein, we analyze 10 microsatellite loci and part of the mitochondrial control region for clarification in such taxonomic debates. We use samples from 168 individuals from 6 geographic populations covering almost all the distribution areas of the species in China to carry out comparisons. Phylogenetic trees derived from both the microsatellite and mitochondrial markers combined with the discriminant analysis of principal components (DAPC) and the STRUCTURE analysis reveal that the individuals in the Helan Mountains are well grouped with a distinct evolutionary lineage and are significantly different from the other populations of P. n. szechuanensis according to Fst values, implying that this isolated population should be categorized as a valid subspecies; namely, Pseudois nayaur alashanicus. The isolation-by-distance (IBD) analysis shows a significant positive relationship between genetic and geographical distances among the populations.

Reliable and Standardized Animal Models to Study the Pathogenesis of Bluetongue and Schmallenberg Viruses in Ruminant Natural Host Species with Special Emphasis on Placental Crossing.

Starting in 2006, bluetongue virus serotype 8 (BTV8) was responsible for a major epizootic in Western and Northern Europe. The magnitude and spread of the disease were surprisingly high and the control of BTV improved significantly with the marketing of BTV8 inactivated vaccines in 2008. During late summer of 2011, a first cluster of reduced milk yield, fever, and diarrhoea was reported in the Netherlands. Congenital malformations appeared in March 2012 and Schmallenberg virus (SBV) was identified, becoming one of the very few orthobunyaviruses distributed in Europe. At the start of both epizootics, little was known about the pathogenesis and epidemiology of these viruses in the European context and most assumptions were extrapolated based on other related viruses and/or other regions of the World. Standardized and repeatable models potentially mimicking clinical signs observed in the field are required to study the pathogenesis of these infections, and to clarify their ability to cross the placental barrier. This review presents some of the latest experimental designs for infectious disease challenges with BTV or SBV. Infectious doses, routes of infection, inoculum preparation, and origin are discussed. Particular emphasis is given to the placental crossing associated with these two viruses.

Large-scale ruminant genome sequencing provides insights into their evolution and distinct traits.

The ruminants are one of the most successful mammalian lineages, exhibiting morphological and habitat diversity and containing several key livestock species. To better understand their evolution, we generated and analyzed de novo assembled genomes of 44 ruminant species, representing all six Ruminantia families. We used these genomes to create a time-calibrated phylogeny to resolve topological controversies, overcoming the challenges of incomplete lineage sorting. Population dynamic analyses show that population declines commenced between 100,000 and 50,000 years ago, which is concomitant with expansion in human populations. We also reveal genes and regulatory elements that possibly contribute to the evolution of the digestive system, cranial appendages, immune system, metabolism, body size, cursorial locomotion, and dentition of the ruminants.

Species dilemma of musk deer (Moschus spp) in India: molecular data on cytochrome c oxidase I suggests distinct genetic lineage in Uttarakhand compared to other Moschus species.

Musk deer are of high conservation priority owing to poaching pressure because of its musk pod. Representation of musk deer status using genetics is poorly documented in India, and it is not confirmed as to how many species of musk deer are present. We characterize for the first time, the genetic diversity of musk deer from Uttarakhand using Cytochrome Oxidase sub-unit (COI) gene (486 bp) and compared with the data available for other species. Results revealed the presence of six haplotypes in the Uttarakhand population amongst 17 sequences. Of these, 12 sequences shared the single haplotype. The intra-species sequences divergence was 0.003-0.017, whereas divergence with other species of musk deer was 0.071-0.081. Bayesian phylogenetic tree revealed that samples from Uttarakhand formed a separate clade with respect to other species of musk deer, whereas three species distributed in China clustered in the same clade and showed low sequences divergence, i.e., 0.002-0.061. Because of different ecomorph reported, we suggest using the barcoding based approach for inter and intra-species distinction and delineating species boundaries across the range for effective conservation. Besides, systematic classification, DNA barcoding would also help in dealing wildlife offence cases for disposal of the legal report in court.

Determination of microbiological characteristics in the digestive tract of different ruminant species.

Holstein dairy cows, Chinese Luxi Yellow cattle, Chinese Laoshan dairy goats, and Chinese Bohai Black cattle were selected for the study. The 16S rDNA sequencing technique was used to analyze the microflora in the digestive tract. The rumen flora in high milk-yield Holstein dairy cows showed significantly higher proportions of Treponema, Butyrivibrio, Coprococcus, Shuttleworthia, Lachnospira, and Selenomonas, compared with the rumen flora in Chinese Bohai Black cattle and Chinese Luxi Yellow cattle (p < 0.05). In addition, the abundances of Succiniclasticum, Ruminococcus, and Fibrobacter in the rumen fluid of high-yield dairy cows were significantly higher than those in rumen flora of dairy goats. Compared with ruminal flora in Chinese Luxi Yellow cattle, the rumen flora in high-yield dairy cattle showed significantly higher Prevotella. Compared with the rumen flora in Chinese Laoshan dairy goats, Chinese Bohai Black cattle, and Chinese Luxi Yellow cattle, the flora in high-yielding dairy cows showed significantly lower proportions of CF231, 02d06, Oscillospira, RFN20, Desulfovibrio, Methanobrevibacter, and SHD-231. In addition, compared with the rumen flora in dairy goats, the rumen flora in high-yielding dairy cattle displayed significantly lower proportion of Enterococcus. Compared with the rumen flora in Chinese Bohai Black cattle, the flora in high-yielding dairy cattle exhibited significantly lower Ruminococcus, YRC22, Pseudobutyrivibrio, L7A_E11, BF311, p-75-a5, and Dehalobacterium. Compared with the rumen flora in Chinese Luxi Yellow cattle, the flora in the high-yield dairy cows also displayed significantly lower proportions of Ruminococcus, YRC22, BF311, Paludibacter, and Dehalobacterium.

Estudo ecodopplercardiográfico em caprinos da raça Moxotó / Doppler echocardiography in goats Moxotó

Objetivou-se com este estudo reportar descrições acerca dos cortes ecocardiográficos no modo bidimensional, das dimensões cardíacas pelo modo unidimensional e dos índices de fluxo Doppler em caprinos da raça Moxotó. Foram utilizados 32 caprinos da raça Moxotó, distribuídos em quatro grupos por categoria de peso corporal, de igual número (n=8), em: G1 (5-10kg), G2 (10-15kg), G3 (15-20kg) e G4 (>20kg). Todos foram submetidos a um registro ecocardiográfico pelos modos bidimensional, modo-M, Doppler pulsado (PW), contínuo (CW) e de fluxo de cores (CF). A formação espectral das imagens ecocardiográficas foi satisfatória, contudo algumas adaptações foram necessárias para obtenção adequada dos cortes nos caprinos acima de 20 kg. Os parâmetros ecocardiográficos em modo unidimensional (IVSd, IVSs, LVIDd, LVIDs, VPWd, LVPWs) e índices de função cardíaco (EF e FS) apresentaram uma correlação descritiva positiva com peso corporal enquadradas nas categorias estudadas. A separação septal do ponto E, mostrou-se constante dentre as categorias de peso investigadas, variando entre 0,1 a 0,41cm em caprinos da raça Moxotó. A relação Em/Am foi predominantemente " >1" em todos os caprinos estudados, com Emax > Amax em todas as categorias, não sendo sujeito a influência da frequência cardíaca dentre as categorias de peso estudados. O mesmo pode ser aplicado ao TRIV, que se mostrou uniforme dentre os intervalos de peso estudados. As velocidades de fluxo da valva aórtica individuais foram superiores a velocidade máxima do fluxo da valva pulmonar. Os tempos de ejeção dos fluxos aórtico e pulmonar apresentaram correlação positiva descritiva com o aumento do peso corporal. Condição também observada sobre o VTI dos espectros de fluxo, dada a relação direta desta variável com o volume sistólico inversamente à FC. O tempo de aceleração (TA) do fluxo pulmonar foi superior ao fluxo aórtico, sendo este relação direta com aumento do peso corporal por categoria estudada e inversamente à frequência cardíaca. Desta forma, a padronização das variáveis ecodopplercardiográficas na espécie caprina, deve sempre considerar particularidades relacionadas ao padrão racial, faixa etária e peso corporal, bem como estudos de repetibilidade e reprodutibilidade e adoção de elementos individuais referenciais para elaboração confiável de valores de normalidade.(AU)

This study describes the two-dimensional echocardiographic sections, M-mode cardiac dimensions, and Doppler flow indices in Moxotó goats. A total of 32 Moxotó goats were divided into four equal groups (n = 8) according to body weight class: G1 (5-10 kg), G2 (10-15kg), G3 (15-20kg) and G4 (>20kg). All animals underwent echocardiographic tests, two-dimensional and M-mode, and pulsed (PW), continuous (CW) and color flow (CF) Doppler. The spectral formation of echocardiographic images was satisfactory, although some adjustments were necessary to obtain adequate cuts/sections for goats above 20 kg. One-dimensional echocardiographic parameters (IVSD, IVSS, LVIDd, LVIDs, VPWd, LVPWs) and cardiac function index (EF and FS) showed a positive descriptive correlation with body weight in the categories studied. The septal separation of point E was constant among the weight categories investigated, ranging from 0.1 to 0.41cm. The Em/Am ratio was predominantly ">1", with Emax> Amax in all weight categories, and not affected by the heart rate among the studied weight classes. The IVRT was also uniform among the studied weight classes. The individual flow rates of the aortic valve were higher than the maximum flow rate of the pulmonary valve. The ejection times of the aortic and pulmonary flows were positively correlated with increasing body weight, something also observed on the VTI of flow spectra, given the direct relationship of this variable with the stroke volume inversely to FC. The acceleration time (AT) of pulmonary blood flow was greater than the aortic flow, and directly related to increasing body weight and inversely with heart rate. Thus, the standardization of Doppler echocardiographic variables in goats, should always consider breed, age and body weight as well as repeatability and reproducibility studies and adoption of individual reference elements for reliable development of normal values.(AU)

Millions of Years Behind: Slow Adaptation of Ruminants to Grasslands.

The Late Cretaceous appearance of grasses, followed by the Cenozoic advancement of grasslands as dominant biomes, has contributed to the evolution of a range of specialized herbivores adapted to new diets, as well as to increasingly open and arid habitats. Many mammals including ruminants, the most diversified ungulate suborder, evolved high-crowned (hypsodont) teeth as an adaptation to tooth-wearing diets and habitats. The impact of different causes of tooth wear is still a matter of debate, and the temporal pattern of hypsodonty evolution in relation to the evolution of grasslands remains unclear. We present an improved time-calibrated molecular phylogeny of Cetartiodactyla, with phylogenetic reconstruction of ancestral ruminant diets and habitats, based on characteristics of extant taxa. Using this timeline, as well as the fossil record of grasslands, we conduct phylogenetic comparative analyses showing that hypsodonty in ruminants evolved as an adaptation to both diet and habitat. Our results demonstrate a slow, perhaps constrained, evolution of hypsodonty toward estimated optimal states, excluding the possibility of immediate adaptation. This augments recent findings that slow adaptation is not uncommon on million-year time scales.

Ruminant-specific multiple duplication events of PRDM9 before speciation.

BACKGROUND: Understanding the genetic and evolutionary mechanisms of speciation genes in sexually reproducing organisms would provide important insights into mammalian reproduction and fitness. PRDM9, a widely known speciation gene, has recently gained attention for its important role in meiotic recombination and hybrid incompatibility. Despite the fact that PRDM9 is a key regulator of recombination and plays a dominant role in hybrid incompatibility, little is known about the underlying genetic and evolutionary mechanisms that generated multiple copies of PRDM9 in many metazoan lineages. RESULTS: The present study reports (1) evidence of ruminant-specific multiple gene duplication events, which likely have had occurred after the ancestral ruminant population diverged from its most recent common ancestor and before the ruminant speciation events, (2) presence of three copies of PRDM9, one copy (lineages I) in chromosome 1 (chr1) and two copies (lineages II & III) in chromosome X (chrX), thus indicating the possibility of ancient inter- and intra-chromosomal unequal crossing over and gene conversion events, (3) while lineages I and II are characterized by the presence of variable tandemly repeated C2H2 zinc finger (ZF) arrays, lineage III lost these arrays, and (4) C2H2 ZFs of lineages I and II, particularly the amino acid residues located at positions -1, 3, and 6 have evolved under strong positive selection. CONCLUSIONS: Our results demonstrated two gene duplication events of PRDM9 in ruminants: an inter-chromosomal duplication that occurred between chr1 and chrX, and an intra-chromosomal X-linked duplication, which resulted in two additional copies of PRDM9 in ruminants. The observation of such duplication between chrX and chr1 is rare and may possibly have happened due to unequal crossing-over millions of years ago when sex chromosomes were independently derived from a pair of ancestral autosomes. Two copies (lineages I & II) are characterized by the presence of variable sized tandem-repeated C2H2 ZFs and evolved under strong positive selection and concerted evolution, supporting the notion of well-established Red Queen hypothesis. Collectively, gene duplication, concerted evolution, and positive selection are the likely driving forces for the expansion of ruminant PRDM9 sub-family.

[Ticks (Acari, ixodidae) of the North Caucasus: Species diversity, host-parasite relationships].

Biological diversity of ixodid tick fauna of the North Caucasus is analyzed. On the whole, 38 tick species are represented in the fauna of the North Caucasus. Their distribution within the region, biotopic features, and host-parasite relationships of different stages of ontogenesis are considered.

New data on the distribution and taxonomy of fossil Soergel's ox (Soergelia sp., Bovidae, Artiodactyla, Mammalia) in Yakutia.

Novel findings of fossil remains of the extinct artiodactyl Soergel's ox, as well as some findings that were not analyzed previously, are presented in the article. Soergelia remains are extremely rare; therefore, the species range of these animals remains uncharacterized by now and the taxonomic positions of some findings are not clear. Analysis of the new material extends the knowledge on the species range and the limits of morphological variation of the Soergel's ox and allowed a more precise assessment of the taxonomic position of the findings from Yakutia.