Genetic diversity and structure of mongolian gazelle (Procapra gutturosa) populations in fragmented habitats.

BACKGROUND: The Mongolian gazelle (Procapra gutturosa) population has shown a considerable range of contractions and local extinctions over the last century, owing to habitat fragmentation and poaching. A thorough understanding of the genetic diversity and structure of Mongolian gazelle populations in fragmented habitats is critical for planning effective conservation strategies. RESULT: In this study, we used eight microsatellite loci and mitochondrial cytochrome b (Cytb) to compare the levels of genetic diversity and genetic structure of Mongolian gazelle populations in the Hulun Lake National Nature Reserve (HLH) with those in the China-Mongolia border area (BJ). The results showed that the nucleotide diversity and observed heterozygosity of the HLH population were lower than those of the BJ population. Moreover, the HLH and BJ populations showed genetic differentiation. We concluded that the HLH population had lower genetic diversity and a distinct genetic structure compared with the BJ population. CONCLUSION: The genetic diversity of fragmented Mongolian gazelle populations, can be improved by protecting these populations while reinforcing their gene exchange with other populations. For example, attempts can be made to introduce new individuals with higher genetic diversity from other populations to reduce inbreeding.

High-Quality Chromosome-Level Genome Assembly of the Corsac Fox (Vulpes corsac) Reveals Adaptation to Semiarid and Harsh Environments.

The Corsac fox (Vulpes corsac) is a species of fox distributed in the arid prairie regions of Central and Northern Asia, with distinct adaptations to dry environments. Here, we applied Oxford-Nanopore sequencing and a chromosome structure capture technique to assemble the first Corsac fox genome, which was then assembled into chromosome fragments. The genome assembly has a total length of 2.2 Gb with a contig N50 of 41.62 Mb and a scaffold N50 of 132.2 Mb over 18 pseudo-chromosomal scaffolds. The genome contained approximately 32.67% of repeat sequences. A total of 20,511 protein-coding genes were predicted, of which 88.9% were functionally annotated. Phylogenetic analyses indicated a close relation to the Red fox (Vulpes vulpes) with an estimated divergence time of ~3.7 million years ago (MYA). We performed separate enrichment analyses of species-unique genes, the expanded and contracted gene families, and positively selected genes. The results suggest an enrichment of pathways related to protein synthesis and response and an evolutionary mechanism by which cells respond to protein denaturation in response to heat stress. The enrichment of pathways related to lipid and glucose metabolism, potentially preventing stress from dehydration, and positive selection of genes related to vision, as well as stress responses in harsh environments, may reveal adaptive evolutionary mechanisms in the Corsac fox under harsh drought conditions. Additional detection of positive selection for genes associated with gustatory receptors may reveal a unique desert diet strategy for the species. This high-quality genome provides a valuable resource for studying mammalian drought adaptation and evolution in the genus Vulpes.

Comparative Analyses of the Gut Microbiome of Two Fox Species, the Red Fox (Vulpes Vulpes) and Corsac Fox (Vulpes Corsac), that Occupy Different Ecological Niches.

The gut microbiome is integral for the host's living and environmental adaptation and crucially important for understanding host adaptive mechanisms. The red fox (Vulpes vulpes) dominates a wider ecological niche and more complicated habitat than that of the corsac fox (V. corsac). However, the adaptive mechanisms (in particular, the gut microbiome responsible for this kind of difference) are still unclear. Therefore, we investigated the gut microbiome of these two species in the Hulunbuir grassland, China, and evaluated their microbiome composition, function, and adaptive mechanisms. We profiled the gut microbiome and metabolism function of red and corsac foxes via 16S rRNA gene and metagenome sequencing. The foxes harbored species-specific microbiomes and functions that were related to ecological niche and habitat. The red fox had abundant Bacteroides, which leads to significant enrichment of metabolic pathways (K12373 and K21572) and enzymes related to chitin and carbohydrate degradation that may help the red fox adapt to a wider niche. The corsac fox harbored large proportions of Blautia, Terrisporobacter, and ATP-binding cassette (ABC) transporters (K01990, K02003, and K06147) that can help maintain corsac fox health, allowing it to live in harsh habitats. These results indicate that the gut microbiome of the red and corsac foxes may have different abilities which may provide these species with differing capabilities to adapt to different ecological niches and habitats, thus providing important microbiome data for understanding the mechanisms of host adaptation to different niches and habitats.

Correction to: Organic Matter Pollution During the Spring Thaw in Hulun Lake Basin: Contribution of Multiform Human Activities.

In the original publication of the article, there was an error in the name of institution. The incorrect name of institution "Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, 8, Jiangwangmiao Road, XuanWu District, 210042 Nanjing, People's Republic of China" should be revised to "Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environmental, 8, Jiangwangmiao Road, XuanWu District, 210042 Nanjing, People's Republic of China". The institution was still the same, but the name of the institution was changed.

Organic Matter Pollution During the Spring Thaw in Hulun Lake Basin: Contribution of Multiform Human Activities.

It has recently been reported that plateau lakes have been seriously polluted by organic matter, however, the sources of this organic matter and their relative contributions remain unknown. In this study, to determine the sources and composition of the organic matter in the Hulun Lake basin during the spring-thaw period, a total of twenty-three sampling sites were investigated. Results showed high levels of organic matter pollution in the surface water of Hulun Lake, with an average COD values of 119.35 mg L-1. Organic matter came from natural sources as well as a variety of anthropogenic activities. The direct sources included urbanization, industrial and residential wastewater discharge, and emission from burning fossile fuels. A large indirect source was organic matter from tumbleweed decomposition, which had increased due to desertification caused by overgrazing. The principal component analysis showed that organic matter from Hulun lake shared composition and sources with the upstream sections of the natural tributaries and the downstream section of the artificial tributary. The artificial inflow river contributed more organic matter than the other tributaries. Notably, a large portion of organic matter in Hulun Lake came from decomposing tumbleweed concentrated in the downstream section of one of the natural rivers. New indirect consequences of human activities must be factored into the rule and regulations that protect plateau lake ecosystems alongside the direct effects of established human activities.

Bacterial and fungal community structures in Hulun Lake are regulated by both stochastic processes and environmental factors.

Microorganisms are a crucial component of lake ecosystems and significant contributors to biogeochemical cycles. However, the understanding of how primary microorganism groups (e.g., bacteria and fungi) are distributed and constructed within different lake habitats is lacking. We investigated the bacterial and fungal communities of Hulun Lake using high-throughput sequencing techniques targeting 16S rRNA and Internal Transcribed Spacer 2 genes, including a range of ecological and statistical methodologies. Our findings reveal that environmental factors have high spatial and temporal variability. The composition and community structures vary significantly depending on differences in habitats. Variance partitioning analysis showed that environmental and geographical factors accounted for <20% of the community variation. Canonical correlation analysis showed that among the environmental factors, temperature, pH, and dissolved oxygen had strong control over microbial communities. However, the microbial communities (bacterial and fungal) were primarily controlled by the dispersal limitations of stochastic processes. This study offers fresh perspectives regarding the maintenance mechanism of bacterial and fungal biodiversity in lake ecosystems, especially regarding the responses of microbial communities under identical environmental stress.IMPORTANCELake ecosystems are an important part of the freshwater ecosystem. Lake microorganisms play an important role in material circulation and energy flow owing to their unique enzymatic and metabolic capacity. In this study, we observed that bacterial and fungal communities varied widely in the water and sediments of Hulun Lake. The primary factor affecting their formation was identified as dispersal limitation during stochastic processes. Environmental and geographical factors accounted for <20% of the variation in bacterial and fungal communities, with pH, temperature, and dissolved oxygen being important environmental factors. Our findings provide new insights into the responses of bacteria and fungi to the environment, shed light on the ecological processes of community building, and deepen our understanding of lake ecosystems. The results of this study provide a reference for lake management and conservation, particularly with respect to monitoring and understanding microbial communities in response to environmental changes.

Evolution of CO2 flux over 60 years: Identifying source and sink changes caused by eutrophication of Hulun Lake.

Understanding the carbon cycling process and assessing the carbon sequestration potential in freshwater lakes relies heavily on their source-sink relationship. However, human activity and climate change have obscured the clarity of this relationship and its driving mechanisms, particularly in northern grassland lakes. This study focused on Hulun Lake, the largest grassland lake in northern China, to quantitatively analyze the carbon dioxide exchange flux (FCO2) at the water-air interface from 1963 to 2023. The analysis revealed significant seasonal, interannual, and decadal variations in the FCO2. Over the past 60 years, FCO2 varying significant in seasons and years has notably decreased, averaging 0.324 ± 0.106 gC·m-2·d-1. Notably, there was a qualitative change in FCO2 from "sink" (0.161 ± 0.109 gC·m-2·d-1) to "source" (-0.130 ± 0.087 gC·m-2·d-1)between 2019 and 2020. From 1963 to 2019, the lake acted as a CO2 source, releasing an average flux of 0.438 ± 0.111 gC·m-2·d-1. During this period, FCO2 was the highest in spring, followed by summer, and the lowest in autumn and winter when the lake was covered by ice. In 2020, the lake transitioned into a CO2 sink with an average FCO2 of -0.248 ± 0.042 gCm-2·d-1 from 2020 to 2023. During this period, FCO2 peaked in autumn, followed by summer and spring, and was lowest in winter when the lake was ice covered. A structural model equation (SEM) was employed to analyze the effects of various factors, including physical, chemical, and biological aspects, on FCO2 and the source-sink pattern of Hulun Lake. This study suggested that lake eutrophication, compounded by global warming, may be the primary driving force behind these changes. Rising temperatures and eutrophication enhanced the primary productivity of the lake. The amount of CO2 fixed through photosynthesis surpassed that emitted by respiration. Consequently, the eutrophication may alter the CO2 exchange pattern in Hulun Lake, shifting it from a "source" to a "sink".

Presumptive First Record of Myotis aurascens (Chiroptera, Vespertilionidae) from China with a Phylogenetic Analysis.

Bat groups have a high degree of species diversity, and the taxonomic status and phylogenetic relationships among bat species have always been research hotspots. Due to the fact that morphological characteristics do not always reflect the evolutionary relationships among species, mitochondrial DNA has been widely used in the study of species relationships due to its maternal inheritance pattern. Myotis aurascens has been suggested as a possible synonym for M. davidii. However, the status of this classification has been controversial. In this study, the morphological and molecular characteristics of a M. aurascens captured from Inner Mongolia, China, were analyzed to determine its taxonomic status. In terms of morphological features, the body weight was 6.33 g, the head and body length were 45.10 mm, the forearm length was 35.87 mm, and the tragus length was 7.51 mm. These values all fell within the species signature data range. Nucleotide skew analysis of the protein-coding genes (PCGs) suggested that only five PCGs (ND1, ND2, COX2, ATP8, and ND4) showed AT-skew value within the mitogenome of M. aurascens. Except for ND6, the GC-skew values of the other PCGs were negative, reflecting the preference for C and T bases compared to G and A bases. Molecular phylogenetic analyses based on mitochondrial PCGs indicated that M. aurascens was a distinct species from M. davidii and phylogenetically closer to M. ikonnikovi, M. alcathoe, and M. mystacinus. Genetic distance analysis also showed that M. aurascens and M. davidii were distantly related. Therefore, the integrated analysis demonstrated that M. aurascens should be considered a distinct species rather than a synonym of M. davidii. Our study could provide a reference for enriching species diversity and research on conservation in China.

The complete mitochondrial genome of Steppe Whiskered Bat (Myotis aurascens; Kuzyakin, 1935) and phylogenetic analysis.

In this study, the complete mitochondrial genome of Steppe Whiskered Bat was sequenced for the first time using muscular tissue. The whole mitochondrial genome was 16,771 bp in length, consisting of two ribosomal RNA genes, 13 protein-coding genes, 22 transfer RNA genes, and one control region (D-loop). Phylogenetic analysis using PAUP based on mitochondrial genome (12 PCGs, except ND6) of 16 other Vespertilionidae species revealed the close relationship of M. aurascens with other related Myotis species.

A chromosome-level genome assembly of the redfin culter (Chanodichthys erythropterus).

Chanodichthys erythropterus is a fierce carnivorous fish widely found in East Asian waters. It is not only a popular food fish in China, it is also a representative victim of overfishing. Genetic breeding programs launched to meet market demands urgently require high-quality genomes to facilitate genomic selection and genetic research. In this study, we constructed a chromosome-level reference genome of C. erythropterus by taking advantage of long-read single-molecule sequencing and de novo assembly by Oxford Nanopore Technology (ONT) and Hi-C. The 1.085 Gb C. erythropterus genome was assembled from 132 Gb of Nanopore sequence. The assembled genome represents 98.5% completeness (BUSCO) with a contig N50 length of 23.29 Mb. The contigs were clustered and ordered onto 24 chromosomes covering roughly 99.49% of the genome assembly with Hi-C data. Additionally, 33,041 (98.0%) genes were functionally annotated from a total of 33,706 predicted protein-coding sequences by combining transcriptome data from seven tissues. This high-quality assembled genome will be a precious resource for future molecular breeding and functional genomics research of C. erythropterus.

Factors affecting seasonal variation of microbial community structure in Hulun Lake, China.

Microbial communities play an important role in water quality regulation and biogeochemical cycling in freshwater ecosystems. However, there is a lack of research on the seasonal variation in lake water microorganisms in cold environments. In this study, 16S rRNA gene high-throughput sequencing was used to explore the microbial community and its influencing factors in Hulun Lake water during different seasons. The results showed that Proteobacteria, Actinobacteria, and Bacteroidetes were the most important phyla in the microbial community of Hulun Lake, but they had significant seasonal differences in their distribution. In addition, significant seasonal differences were observed in the α diversity of microorganisms, with bacterial diversity being higher in winter than in summer. Changes in environmental variables were significantly correlated with changes in the microbial community, and the rapid changes in temperature, pH, and dissolved oxygen are potentially the major factors influencing seasonal bacterial diversity trends. The findings of the present study enhance our understanding of the microbial communities in alpine lake ecosystems and are of great significance for the management and protection of lake ecosystems.

Comparative Analysis of the Gut Microbiota of Mongolian Gazelle (Procapra gutturosa) Under Fragmented Habitats.

The existence of man-made facilities such as pasture fences makes the grassland ecosystem fragmented and endangers the survival of local wild animals. The Mongolian gazelle is highly sensitive to hunting and habitat destruction, and is one of the most threatened artiodactyls in Eurasia. It provides a critical model to studying gut microbiota under fragmented habitats. Therefore, we applied metagenomics sequencing to analyze the gut microbiota communities and functions of Mongolian gazelle under fragmented habitats. The results demonstrated that there were no significant differences in gut microbial communities between the different groups at both the phylum and genus level. The functional analyses showed that the Mongolian gazelle in fragmented habitat had a stronger ability to degrade naphthalene, but their ability to absorb carbohydrates was weaker. This study provided fundamental information about the gut microbiota of Mongolian gazelle, and we recommend reducing habitat fragmentation to better protect the Mongolian gazelle.

Transcriptome analysis provides new insights into cold adaptation of corsac fox (Vulpes Corsac).

Vulpesare widely distributed throughout the world and have undergone drastic physiological and phenotypic changes in response to their environment. However, little is known about the underlying genetic causes of these traits, especially Vulpes corsac. In this study, RNA-Seq was used to obtain a comprehensive dataset for multiple pooled tissues of corsac fox, and selection analysis of orthologous genes was performed to identify the genes that may be influenced by the low-temperature environment. More than 6.32 Gb clean reads were obtained and assembled into a total of 173,353 unigenes with an average length of 557 bp for corsac fox. Selective pressure analysis showed that 16 positively selected genes (PSGs) were identified in corsac fox, red fox, and arctic fox. Enrichment analysis of PSGs showed that the LRP11 gene was enriched in several pathways related to the low-temperature response and might play a key role in response to environmental stimuli of foxes. In addition, several positively selected genes were related to DNA damage repair (ELP2 and CHAF1A), innate immunity (ARRDC4 and S100A12), and the respiratory chain (NDUFA5), and these positively selected genes might play a role in adaptation to harsh wild fox environments. The results of common orthologous gene analysis showed that gene flow or convergent evolution might be an important factor in promoting regional differentiation of foxes. Our study provides a valuable transcriptomic resource for the evolutionary history of the corsac fox and the adaptations to the extreme environments.

Environmental factors and stochasticity affect the fungal community structures in the water and sediments of Hulun Lake, China.

Aquatic fungi form both morphologically and ecologically diverse communities. However, lake ecosystems are frequently overlooked as fungal habitats, despite the potentially important role of fungi in matter cycling and energy flow. Hulun Lake is a typical example of a seasonal glacial lake; however, previous studies have only focused on bacteria in this ecosystem. Therefore, in the current study, internal transcribed spacer ribosomal RNA (ITS rRNA) gene high-throughput sequencing was used to investigate the fungal communities in paired water and sediment samples from the Hulun Lake Basin in China. A significant difference was found between the fungal communities of the two sample types. Across all samples, we identified nine phyla, 30 classes, 78 orders, 177 families, and 307 genera. The dominant phyla in the lake were Ascomycota, Basidiomycota and Chytridiomycota. Our results show that both water and sediments have very high connectivity, are dominated by positive interactions, and have similar interaction patterns. The fungal community structures were found to be significantly affected by environmental factors (temperature, chemical oxygen demand, electrical conductivity, total phosphorus, and pH). In addition, the dispersal limitations of the fungi affected the structure of the fungal communities, and it was revealed that stochasticity is more important than deterministic mechanisms in influencing the structure and function of fungal communities. This study provides unique theoretical support for the study of seasonally frozen lake fungal communities and a scientific basis for the future management and protection of Hulun Lake.

The complete mitochondrial genome of Turdus obscurus (Passeriformes: Turdidae).

The Eyebrowed Thrush (Turdus obscurus) is a highly migratory bird, which breeds in northeastern Asia and overwinters in southeastern Asia. We obtained the mitochondrial genome of T. obscurus by Sanger sequencing. The mitogenome was 16,739 bp in length, which contains 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and one control region. Its composition is consistent with the species in genus Turdus. Phylogenetic analysis based on the whole mitochondrial genome showed that the relationship between T. obscurus and Turdus kessleri was relatively close. This study improves the understanding of phylogeny and genetics of Turdidae and Muscicapoidea.

Warming-driven shifts in ecological control of fish communities in a large northern Chinese lake over 66 years.

Warming, land-use change, and habitat loss are three major threats to aquatic biodiversity worldwide under the influences of anthropogenic disturbances. Positive feedback between warming and bottom-up regulation may cause irreversible ecological regime shifts. Threshold dynamics of interspecific interactions have been rarely studied in freshwater fish communities using threshold community models. Here we use 66 years (1950-2015) of data to link four ecological regime shifts of 9-species fish communities to climatic and land use changes in Lake Hulun, the largest freshwater lake of Northern China. Overfishing caused the collapse of piscivorous fish populations and an ecological regime shift of Lake Hulun in the late 1950s. The first recorded algal bloom of Lake Hulun took place in 1986, with accelerated warming and rapid increases in livestock grazing. The dominance of planktivorous minnow populations reduced fish biodiversity in a nonlinear, threshold manner when annual mean ambient temperature was >0.12 °C. Multivariate environmental vector regression demonstrated that warming, eutrophication, and water-storage reduction (i.e., habitat loss) were related to three ecological regime shifts of Lake Hulun from 1960 to 2015. Multivariate autoregressive models (MAR) did not detect predation by piscivorous fish in Lake Hulun after 1960. Threshold MAR models indicated that dominant minnow populations and other prey fish populations switched from top-down to bottom-up control during the 1980s. Sustained positive feedback between warming, the dominance of planktivorous fish populations, and bottom-up regulation caused predator-prey role reversal, and probably resulted in three regime shifts of Lake Hulun over 56 years. This study provides a comprehensive analysis of ecological regime shifts in Hulun Lake fish communities, and has potential implications for fish species living in similar environments that are subject to global warming, land-use changes, and overfishing.

Comparative transcriptome provides insights into the selection adaptation between wild and farmed foxes.

The silver fox and blue fox are economically important fur species and were domesticated by humans from their wild counterparts, the arctic fox and red fox, respectively. Farmed foxes show obvious differences from their wild counterparts, including differences in physiology, body size, energy metabolism, and immunity. However, the molecular mechanisms underlying these differences are presently unclear. In this study, we built transcriptome libraries from multiple pooled tissues for each species of farmed fox, used RNA-seq to obtain a comprehensive dataset, and performed selection analysis and sequence-level analyses of orthologous genes to identify the genes that may be influenced by human domestication. More than 153.3, 248.0, 81.6, and 65.8 million clean reads were obtained and assembled into a total of 118,577, 401,520, 79,900, and 186,988 unigenes with an average length range from 521 to 667 bp for AF, BF, RF, and SF, respectively. Selective pressure analysis showed that 11 and 14 positively selected genes were identified, respectively, in the two groups (AF vs. BF and RF vs. SF). Several of these genes were associated with natural immunity (CFI and LRRFIP1), protein synthesis (GOLGA4, CEP19 and SLC35A2), and DNA damage repair (MDC1). Further functional enrichment analyses demonstrated that two positively selected genes (ACO1 and ACAD10) were involved in metabolic process (GO:0008152, p-value = .032), representing a significant enrichment. Sequence analysis of 117 orthologous genes shared by the two groups showed that the LEMD2, RRBP1, and IGBP1 genes might be affected by artificial selection in farmed foxes, with mutation sites located within sequences that are otherwise highly conserved across most mammals. Our results provide a valuable transcriptomic resource for future genetic studies and improvement in the assisted breeding of foxes and other farmed animals.

The complete mitochondrial genome of Daurian jackdaw (Corvus dauuricus).

In this study, the complete mitochondrial genome of Daurian jackdaw (Corvus dauuricus, Pallas, 1776) was sequenced and deposited to GeneBank for the first time using muscle tissue. This mitochondrial genome is a circular molecule of 16921 bp in length and sequence analysis showed it contains 2 rRNA genes, 22 tRNA genes, 13 protein-coding genes and D_loop. The phylogenetic analysis basis of 12 protein-coding genes except for ND6 gene of 13 species shows that most of the genus of Corvus were grouped into two clades, and C. dauuricus was basal to all other Corvus.

The complete mitochondrial genome of Sorex minutissimus (Eulipotyphla: Soricidae).

In this study, the complete mitochondrial genome of Sorex minutissimus was sequenced and deposited to GeneBank for the first time using muscle tissue. This mitochondrial genome is a circular molecule of 16,700 bp in length and sequence analysis showed it contains 2 rRNA genes, 22 tRNA genes, 13 protein-coding genes, rep_origin, and D_loop. Phylogenetic analysis on the basis of 12 protein-coding genes except ND6 of 13 Soricidae species' mitochondrial genomes using ML and BI demonstrated that S. minutissimus and other Sorex species were clustered into same clade.

Total Arsenic, pH, and Sulfate Are the Main Environmental Factors Affecting the Microbial Ecology of the Water and Sediments in Hulun Lake, China.

Bacteria have the metabolic potential to produce a diverse array of secondary metabolites, which have important roles in biogeochemical cycling processes. However, for Hulun Lake and the rivers that enter into it, the bacterial community structures and their effects have not previously been widely studied, limiting our ecological understanding of this habitat. To address this, we have analyzed the bacterial communities in the water ecosystem of the Hulun Lake Basin. 16S rRNA high-throughput sequencing identified 64 phyla, 165 classes, 218 orders, 386 families, and 740 genera of bacteria across all samples. The dominant phyla in the central area of the lake were Proteobacteria, Actinobacteria, Firmicutes, and Cyanobacteria, while in all other areas, Proteobacteria, Actinobacteria, and Bacteroidetes were dominant. The microbial community structures were significantly affected by environmental factors [arsenic (As), pH, and sulfate (SO4 2-)] and their location in the lake. The species richness in the sediments of Hulun Lake was higher than in the water, and this ecosystem harbored the highest proportion of unclassified sequences, representing unclassified bacteria. This study provides basic data for future investigations into the Hulun lake ecosystem and for water microbial monitoring and protection measures.