Alpine Extremophytes in Evolutionary Turmoil: Complex Diversification Patterns and Demographic Responses of a Halophilic Grass in a Central Asian Biodiversity Hotspot.

Diversification and demographic responses are key processes shaping species evolutionary history. Yet we still lack a full understanding of ecological mechanisms that shape genetic diversity at different spatial scales upon rapid environmental changes. In this study, we examined genetic differentiation in an extremophilic grass Puccinellia pamirica and factors affecting its population dynamics among the occupied hypersaline alpine wetlands on the arid Pamir Plateau in Central Asia. Using genomic data, we found evidence of fine-scale population structure and gene flow among the localities established across the high-elevation plateau as well as fingerprints of historical demographic expansion. We showed that an increase in the effective population size could coincide with the Last Glacial Period, which was followed by the species demographic decline during the Holocene. Geographic distance plays a vital role in shaping the spatial genetic structure of P. pamirica alongside with isolation-by-environment and habitat fragmentation. Our results highlight a complex history of divergence and gene flow in this species-poor alpine region during the Late Quaternary. We demonstrate that regional climate specificity and a shortage of nonclimate data largely impede predictions of future range changes of the alpine extremophile using ecological niche modeling. This study emphasizes the importance of fine-scale environmental heterogeneity for population dynamics and species distribution shifts.

Halomonas jincaotanensis sp. nov., isolated from the Pamir Plateau degrading polycyclic aromatic hydrocarbon.

A Gram-strain-negative, rod-shaped, aerobic bacterium, designated strain TRM 85114T, was isolated from the Jincaotan wetland in the Pamir Plateau of China. This strain grew optimally at 30 °C and pH 6.0 in the presence of 3% (w/v) NaCl. Phylogenetic analysis of 16S rRNA gene sequences revealed that strain TRM 85114T was affiliated with the genus Halomonas, and shared high sequence similarity with Halomonas korlensis XK1T (97.3%) and Halomonas tibetensis pyc13T (96.4%). Strain TRM 85114T contained C16:0 and C19:0 cyclo ω8c as primary cellular fatty acids, Q-9 as predominate respiratory quinone, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phospholipids of unknown structure containing glucosamine, unidentified aminophospholipids, unidentified lipids and three unidentified phospholipids as the major polar lipids. The complete genome of TRM 85114T comprised 3,902 putative genes with a total of 4,126,476 bp and a G + C content of 61.6%. The average nucleotide identity and digital DNA-DNA hybridization values between strain TRM 85114T and related type Halomonas strains of H. korlensis XK1T, H. tibetensis pyc13T, Chromohalobacter salexigens DSM 6768T, and Halomonas urumqiensis BZ-SZ-XJ27T were 75.4-88.9% and 22.9-39.2%, respectively. Based on phenotypic, chemotaxonomic, and molecular features, strain TRM 85114T represents a novel species of the genus Halomonas, for which the name is proposed as Halomonas jincaotanensis sp. nov.. The type strain is TRM 85114T (CCTCC AB 2021006T = LMG 32311T). The amount of 1-naphthylamine degradation by strain TRM 85114T reached up to 32.0 mg/L in 14 days.

Pontibacter pamirensis sp. nov., isolated from saline-alkaline soil.

A novel bacterium, designated TRT317T, was isolated from saline-alkaline soil collected from the Pamir plateau in northwest China. Cells of this strain were Gram-stain-negative, aerobic rods and red-pink-coloured. Phylogenetic analysis using 16S rRNA gene sequences indicated that strain TRT317T showed the highest sequence similarity to the type strains of Pontibacter diazotrophicus (96.3 %) and Pontibacter yuliensis (96.2 %). Growth was observed at 4-40 °C, pH 6.0-10.0 and in the presence of up to 7 % (w/v) NaCl. The major fatty acids were iso-C15 : 0 and summed feature 4 (iso-C17 : 1 I/anteiso-C17 : 1 B). The polar lipids included phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified phospholipid, four unidentified glycolipids and five unidentified lipids. The whole-cell sugars of strain TRT317T were mannose, rhamnose, glucose, galactose, xylose, arabinose and four unidentified sugars. The sole respiratory quinone was MK-7. The genomic DNA G+C content of strain TRT317T was 47.7 mol%. The average nucleotide identity (ANI) value of strain TRT317T with P. diazotrophicus was 88.3 %, which is below the standard ANI threshold for species identification (95-96 %). Combined results of physiological, genotypic, phylogenetic and chemotaxonomic analyses demonstrated that strain TRT317T represents a novel species within the genus Pontibacter, for which the name Pontibacter pamirensis sp. nov. is proposed. The type strain is TRT317T (=CGMCC1.18690T=KCTC 82818T).

Border fences reduce potential for transboundary migration of Marco Polo Sheep (Ovis ammon polii) in the Pamir Plateau.

Border fences have severely impeded the transboundary migration of a number of large mammals worldwide, with central Asia being one of the most impacted. The Marco Polo sheep (Ovis ammon polii), an iconic species of Pamir, is threatened in its transboundary movement by increasing border fencing among their five distributed countries, including Tajikistan, Kyrgyzstan, China, Afghanistan, and Pakistan. In this study, by building ensemble species distribution models, we found that eastern Tajikistan had the largest suitable Macro Polo sheep habitat (about 42 % of the total suitable habitat), followed by China (about 32 %). We used least-cost paths to identify 51 ecological corridors including 5 transboundary ecological corridors, which may be important to maintain connectivity in both domestic and transboundary regions. To assess the potential barrier effect of border fences, we assessed four scenarios (30, 40, 50 and 60°) corresponding to the upper limit of the slope for the construction of fences. In areas too steep for fencing, these could be used by wild sheep to cross barriers or borders and may represent migration or movement routes, defined as natural passages. In the most pessimistic Scenario 60, only 25 migratory passages along the border fences were identified, compared to 997 in the most optimistic scenario (Scenario 30), indicating a strong negative effect of intensive border fencing on the transboundary movement of Marco Polo sheep. The establishment of transnational conservation parks, and ensuring permeability is maintained in key areas, could have a positive impact on the connectivity and persistence of Marco Polo sheep populations, and provide important lessons for other large migratory mammals in transboundary regions.

Composition and distribution of bacterial communities and potential radiation-resistant bacteria at different elevations in the eastern Pamirs.

Altitude and ultraviolet (UV) radiation may affect the community composition and distribution of microorganisms in soil ecosystems. In this study, 49 soil samples from 10 locations were collected from different elevations on the eastern Pamir Plateau and analyzed for soil microbial community structure and function using high-throughput sequencing. The results showed that soil samples from different elevations of the eastern Pamir Plateau contained 6834 OTUs in 26 phyla and 399 genera. The dominant phyla common to different elevations were Actinobacteria, Proteobacteria, Bacteroidota, Acidobacteriota, and Gemmatimonadota. The dominant genera were Rubrobacter, Sphingomonas, Nocardioides, and Solirubrobacter. Species richness increased slightly with elevation, and there were significant differences in community composition between the elevations. Elevation and UV exposure are important factors that drive changes in bacterial communities. The results of the KEGG pathway showed that drug resistance, antineoplastic, aging, replication, and repair were enhanced and then slightly decreased with increasing elevation. Bacterial communities at different elevations were rich in radiation-resistant microorganisms, and the main genera were Rubrobacter, Sphingomonas, Nocardioides, Pontibacter, and Streptomyces. The findings have shown the composition and distribution of bacterial communities at different elevations on the Eastern Pamir Plateau. Potentially radiation tolerant microbial species were also examined. The results are of considerable importance for the succession of bacterial microorganisms in the plateau region, the study of radiation tolerant bacterial germplasm resources, and the application of biofunctionality.

[Potential impacts of climate change on suitable habitats of Marco Polo sheep in China]. / 气候变化对中国马可波罗盘羊适宜生境的潜在影响.

Climate change may lead to biodiversity loss and species extinction. Understanding the impacts of climate change on the distribution pattern of endangered species is of great value to the identification of priority reserves and the formulation of relevant conservation strategies. Based on the distribution data of Marco Polo sheep (Ovis ammon polii) obtained from the field survey in Taxkorgan Nature Reserve (TNR) in Xinjiang during 2017-2018, the maximum entropy (MaxEnt) model was used to predict the distribution pattern of its suitable habitat under climate change. The results showed that the suitable habitat of Marco Polo sheep was mainly distributed in the northwest of the TNR, with temperature as the key factor affecting its suitable habitat distribution. Under the medium and high emission concentration (RCP4.5 and RCP8.5), the suitable habitat area of Marco Polo sheep would decrease in the next two periods (2050s and 2070s), with the loss rate of suitable habitat being as high as 40.5%. The loss of suitable habitat was mainly located in the low-altitude area, while the area of suitable habitat increased correspondingly in the high-altitude area. The area of suitable habitat from low elevation to high elevation increased with the increases of greenhouse gas emission concentration. According to the results of centroid transfer, the suitable habitat was mainly moved to the west, namely Tajikistan, the main distribution country of Marco Polo sheep.