Plateau Zokor Research Articles

Ingesting Stellera chamaejasme Significantly Impacts the Gastrointestinal Tract Bacterial Community and Diversity in Plateau Zokors (Eospalax baileyi)

Intestinal bacteria are considered the “second genome” of the host, playing a crucial physiological role in assisting the host in degrading plant secondary compounds, nutrient absorption, immune regulation, and other aspects. To explore the effects of Stellera chamaejasme on the bacterial community of the gastrointestinal tract of plateau zokor, this study uses the 16S rRNA gene high-throughput sequencing technology, and the biodiversity and the community structure of gut bacteria in different gastrointestinal tract segments (the stomach and cecum) of plateau zokors. The results showed that at the phylum level, the dominant flora in the stomach and cecum of plateau zokors before and after ingesting Stellera chamaejasme were Firmicutes and Bacteroidetes. In plateau zokors that ingested Stellera chamaejasme, the relative abundance of Firmicutes in the stomach and cecum decreased, the relative abundance of Bacteroidetes increased, and the ratio of Firmicutes to Bacteroidetes decreased. After plateau zokors ingested Stellera chamaejasme, the ACE index demonstrated a significant reduction in the richness of the stomach bacterial community, while cecal bacterial community richness showed no significant change. Stellera chamaejasme exhibits significantly different effects on the bacterial communities in different segments of the gastrointestinal tract. Beta diversity analysis revealed that, after plateau zokors ingested Stellera chamaejasme, there were notable distinctions in the bacterial communities within both the stomach and cecum, alongside a marked reduction in the variability of the intestinal bacterial profiles across individuals. The results show that ingesting Stellera chamaejasme has a significant impact on the composition and structure of the gastrointestinal tract bacterial community in plateau zokors.

Impacts of climate change and human activities on three Glires pests of the Qinghai-Tibet Plateau.

The range of Glires is influenced by human activities and climate change. However, the extent to which human activities and environmental changes have contributed to this relationship remains unclear. We examined alterations in the distribution changes and driving factors of the Himalayan marmot, plateau pika, and plateau zokor on the Qinghai-Tibet Plateau (QTP) using the maximum entropy (MaxEnt) model and a geographical detector (Geodetector). The MaxEnt model showed that the contribution rates of the human footprint index (HFI) to the distribution patterns of the three types of Glires were 46.70%, 58.70%, and 59.50%, respectively. The Geodetector results showed that the distribution pattern of the Himalayan marmot on the QTP was influenced by altitude and the normalized difference vegetation index (NDVI). The distribution patterns for plateau pikas and plateau zokors were driven by HFI and NDVI. Climate has played a substantial role in shaping suitable habitats for these three Glires on the QTP. Their suitable area is expected to decrease over the next 30-50 years, along with their niche breadth and overlap. Future suitable habitats for the three Glires tended to shift toward higher latitudes on the QTP. These findings underscore the impacts of environmental and human factors on the distribution of the three Glires on the QTP. They have enhanced our understanding of the intricate relationships between Glires niches and environments. This can aid in identifying necessary interventions for developing effective early warning systems and prevention strategies to mitigate Glires infestations and plague epidemics on the QTP. © 2024 Society of Chemical Industry.

Seasonal piRNA Expression Profile Changes in the Testes of Plateau Zokor (Eospalax baileyi).

Seasonal reproduction is a mammalian behavior that has developed over an extended evolutionary period and requires animals to respond to external environmental changes to facilitate reproduction. In this study, we investigated the role of PIWI-interacting RNA (piRNA) in the seasonal reproduction of plateau zokors (Eospalax baileyi). piRNA expression profiles in plateau zokor testes during both breeding and non-breeding seasons were examined. The piRNAs had a distinctive ping-pong signature and ranged from 27 to 32 nt with a peak at 30 nt. Testicular piRNAs predominantly aligned to specific genomic regions, including repeat and gene regions. Analysis of the piRNA-mRNA interaction network and functional enrichment of differentially expressed piRNAs targeting mRNAs revealed their association with testicular development and spermatogenesis. Significantly, PIWIL4 is an mRNA gene that interacts with piRNA and exhibits high expression levels within the testes during the non-breeding phase. This study provides a foundation to improve our understanding of piRNA regulatory mechanisms during testicular development and spermatogenesis in seasonally reproducing animals and, specifically, in the plateau zokor.

Plateau zokor disturbance enhances soil bacterial diversity and reduces network complexity

Rodent disturbances are considered as the key factors that affect grassland ecological restoration worldwide. Although the impact of rodent disturbances on plant diversity and ecosystem functions has been extensively studied, our understanding of how such activities shape soil bacterial community networks and their functional roles remains limited. In this study, we employed 16S rRNA sequencing to investigate soil bacterial communities between undisturbed alpine meadow and zokor mounds at different successional stages. Additionally, we analyzed the co-occurrence networks and potential functions within the alpine meadow ecosystem. The results revealed that (1) the disturbance by plateau zokors altered the soil bacterial community structure, increased bacterial diversity and reduced network complexity. Also, there were synergistic interactions among key species in the soil bacterial co-occurrence network; (2) soil organic carbon (SOC) and total nitrogen (TN) were identified as the key environmental variables that shape soil bacterial communities; (3) functional predictions based on FAPROTAX indicated that the disturbance by plateau zokors significantly affected the functional groups involved in carbon (C) and nitrogen (N) cycling. Overall, these findings significantly enhance our understanding of how small mammal activities influence the soil nutrient cycling and bacterial community in the Qinghai-Tibet Plateau (QTP) alpine meadow.

Spermatocytes are the terminals of germ cell differentiation in plateau zokor (Eospalax baileyi) during the non-breeding season.

Plateau zokor (Eospalax baileyi) is a subterranean rodent and seasonal breeder. During the non-breeding season, the testicles regress, leading to the arrest of spermatogenesis and loss of fertility. The identification of the specific germ cell type at which spermatogenesis is arrested, as well as potential regulatory factors during the non-breeding season, is important for understanding seasonal spermatogenesis in subterranean species. This study analyzed genes in spermatocytes of plateau zokor by referring to single-cell RNA results in mice. We discovered that spermatogenesis is arrested at the spermatocyte during the non-breeding season, which was corroborated via immunofluorescence staining results. The analysis of gene expression during different stages of meiotic prophase I has revealed that germ cell development may be arrested, starting from zygonema, during the non-breeding season. Meanwhile, we discovered that the apoptosis genes were up-regulated, leading to apoptosis in spermatocytes. To confirm that the germ cell differentiation was blocked during the non-breeding season due to a decrease in the androgen level, we used androgen receptor antagonist (flutamide) to intervene in the breeding season and found that the inner diameter of the seminiferous tubules was significantly reduced, spermatogenesis was arrested, and spermatocytes underwent apoptosis. This study revealed that spermatocytes are the terminal of germ cell differentiation in plateau zokor during the non-breeding season and that the arrest of differentiation is attributed to a decline in androgen levels. Our results complement the theoretical basis of seasonal reproduction in plateau zokor.

Effect of foraging tunnels created by small subterranean mammals on soil microbial biomass carbon and organic carbon storage in alpine grasslands

Extensive foraging tunnel disturbances created by small subterranean mammals have important impacts on soil physical properties and nutrients in grasslands. This study took plateau zokor (Eospalax baileyi) as an example mammal to investigate the impacts of foraging tunnel disturbances by small subterranean mammals on soil microbial biomass carbon (SMBC) and soil organic carbon (SOC) storage. A paired design was used to locate 90 tunnel quadrats and 90 non-tunnel quadrats in alpine grasslands across three sites. This study showed that SMBC, SOC concentrations and SOC storage in tunnel quadrats were 47.4 %, 26.8 % and 22.0 % lower than those in non-tunnel quadrats, respectively. This study also showed that soil microbial biomass nitrogen was a major factor affecting SOC storage in non-tunnel quadrats, while it was not a major factor in tunnel quadrats. Soil pH and soil ammonium nitrogen were not major factors in non-tunnel quadrats, while they were the major factors influencing SOC storage in tunnel quadrats. In contrast to non-tunnel quadrats, foraging tunnel disturbances led to a new pathway in which soil pH positively affected SOC storage in tunnel quadrats. The findings of this study demonstrated that foraging tunnel disturbances had negative impacts on soil fertility due to lower SMBC concentrations and might cause soil carbon loss in alpine grasslands because of lower SOC storage. Given the effect of foraging tunnels on soil carbon cycling and climate regulation in the Qinghai-Tibet Plateau's alpine grasslands, it is crucial to take them into account when assessing grassland carbon storage and formulating strategies for effective grassland management and conservation.

Two plants improve stress response of a subterranean herbivore by downregulating amphetamine addiction pathways.

Captivity serves as the primary method for enhancing animal survival and productivity. However, the stress induced by confinement can hinder animal growth and reproduction. The administration of drugs to captive animals can effectively regulate their stress response and can also be used inartificial breeding, reproduction, and experimental animalization of wild species. The plateau zokor (Eospalax baileyi), a subterranean herbivore, experiences significant stress during the captive process owing to its unique habitat. In our study, we utilized Radix astragali (RA) and Acanthopanax senticosus (AS) extracts to intervene in the stress response of plateau zokors. Our findings demonstrated that RA and AS treatment considerably improved food intake and reduced weight loss, stress-related behavior, and stress hormone levels in plateau zokors. Furthermore, the excitatory pathway of amphetamine addition in the hypothalamus was suppressed by RA and AS treatment, acting through the Grin and Prkc gene families. Notably, after RA treatment, the extracellular matrix-receptor interaction pathway, enriched by the Col1a1/3a1/1a2/6a1 gene, was significantly upregulated, potentially enhancing the immune function of captive plateau zokors. In conclusion, our research demonstrates that RA and AS treatment can effectively alleviate the stress response of plateau zokors in captive environments. The downregulation of the excitation pathway and upregulation of the immune pathway offer valuable insights into the response and potential mechanisms of plant-based drugs in mitigating animal stress.

Simulation of Soil Temperature under Plateau Zokor's (Eospalax baileyi) Disturbance in the Qinghai Lake Watershed, Northeast Qinghai-Tibet Plateau.

The soil temperature is a key factor affecting the fragile terrestrial ecosystems on the Qinghai-Tibet Plateau, and has been remarkably altered by the soil mammal's disturbance. This study first analyzed the soil temperature variation in grassland, mound, and bald patch under the disturbance of plateau zokor (Eospalax baileyi) from October 2018 to July 2020 in the Qinghai Lake watershed. Then, the SHAW (simultaneous heat and water) model was used to simulate the soil temperature change of three land surface types, and the sensitivity of soil temperature to environmental parameters before and after the disturbance was explored. The results showed the following: (1) The daily range of soil temperature was mound > bald patch > grassland, which became smaller as the depth increased, due to the co-influence of vegetation coverage and soil bulk density. There was an obvious hysteresis of soil heat transfer for grassland, as compared with mound and bald patch, especially at 5 and 15 cm depths. (2) The SHAW model was applicable for the simulation of soil temperature under the plateau zokor's disturbance, especially during the growing season, and had better simulation accuracy for deep soil. (3) Air-entry potential and pore-size distribution index obviously affected soil temperature change, because of the change in root system and soil pores under the plateau zokor's disturbance. With the evolution of disturbance process, the response of soil temperature to the leaf area index weakened gradually, owing to the different duration of disturbance and restoration. In general, the plateau zokor's disturbance alters the soil properties and vegetation characteristics, and further, distinctly affects heat transfer and soil temperature.

Effects of foraging tunnels created by plateau zokors on plant above‐ground biomass and species richness of graminoids and forbs in alpine grasslands

AbstractQuestionForaging‐tunnel disturbances created by herbivorous mammals can influence the above‐ground plant biomass of grassland communities. The plateau zokor (Eospalax baileyi) was considered a focal animal for investigating the effect of foraging‐tunnel disturbances created by herbivorous mammals on the above‐ground biomass and species richness of graminoids and forbs. Here, we ask how foraging‐tunnel disturbances created by plateau zokors influences above‐ground plant biomass and species richness of graminoids and forbs in alpine grasslands.LocationThe study was conducted at three sites of alpine grasslands in the Qinghai‐Tibetan Plateau, China.MethodsIn this study, all vascular plants were divided into graminoids and forbs, and 30 paired quadrats were randomly selected from each site. In total, 90 tunnel quadrats and 90 non‐tunnel quadrats were surveyed and sampled.ResultsThis study showed that foraging‐tunnel disturbances decreased the plant species richness of the grassland community and forbs by 16.5% and 17.7% respectively, whereas the response of graminoid species richness to foraging‐tunnel disturbance was different among the three sites, in which foraging‐tunnel disturbance decreased the graminoid species richness at Maqu and Xiahe sites and had no impact on the graminoid species richness at Tianzhu site. Regarding forbs, some legumes identified in the non‐tunnel quadrats were not observed in the tunnel quadrats. The foraging‐tunnel disturbances resulted in an above‐ground plant biomass decrease of 21.9% in the grassland community, 27.3% in forbs, and 17.2% in graminoids respectively. The percentage of graminoids in the above‐ground plant biomass increased from 50.4% in non‐tunnel quadrats to 55.5% in tunnel quadrats, a relative increase of 10.1% from the initial percentage.ConclusionsThese results indicate that the foraging‐tunnel disturbances seemed to improve the forage availability for livestock in tunnel quadrats due to a higher relative proportion of graminoids in the grassland plant community, despite a decrease in graminoid biomass. However, the tunnels not only decreased the above‐ground plant biomass and species richness of forbs, but also might have a negative impact on soil nitrogen input because of the absence of some legumes. The findings of this study suggest that reseeding some legumes is an effective approach to maintaining plant diversity and soil fertility, which can compensate for the negative effect of foraging‐tunnel disturbance on alpine grasslands.

RegCloser: a robust regression approach to closing genome gaps

BackgroundClosing gaps in draft genomes leads to more complete and continuous genome assemblies. The ubiquitous genomic repeats are challenges to the existing gap-closing methods, based on either the k-mer representation by the de Bruijn graph or the overlap-layout-consensus paradigm. Besides, chimeric reads will cause erroneous k-mers in the former and false overlaps of reads in the latter.ResultsWe propose a novel local assembly approach to gap closing, called RegCloser. It represents read coordinates and their overlaps respectively by parameters and observations in a linear regression model. The optimal overlap is searched only in the restricted range consistent with insert sizes. Under this linear regression framework, the local DNA assembly becomes a robust parameter estimation problem. We solved the problem by a customized robust regression procedure that resists the influence of false overlaps by optimizing a convex global Huber loss function. The global optimum is obtained by iteratively solving the sparse system of linear equations. On both simulated and real datasets, RegCloser outperformed other popular methods in accurately resolving the copy number of tandem repeats, and achieved superior completeness and contiguity. Applying RegCloser to a plateau zokor draft genome that had been improved by long reads further increased contig N50 to 3-fold long. We also tested the robust regression approach on layout generation of long reads.ConclusionsRegCloser is a competitive gap-closing tool. The software is available at https://github.com/csh3/RegCloser. The robust regression approach has a prospect to be incorporated into the layout module of long read assemblers.

Comparative analysis of microRNA and messengerRNA expression profiles in plateau zokor testicular cells under reproductive suppression.

Reproductive suppression is an adaptive strategy that affects the success rate and reproductive efficiency in animals, which in turn affects population continuation and evolution. However, no studies on the miRNAs in testicular development and spermatogenesis regulatory mechanisms under reproductive suppression have been reported. In this study, the differentially expressed (DE) miRNAs, miRNA-mRNA interaction network and function of the plateau zokor testicular cells of non-breeders and breeders during the breeding season were comprehensively analyzed by transcriptomics. In total, 381 known and 94 novel miRNAs were determined. Compared with that in the breeders, 70 downregulated and 68 upregulated DE miRNAs were identified in the non-breeders. We predicted 1670 significant target mRNAs by analyzing the miRNA and mRNA expression profiles. According to the miRNA-mRNA interaction network, the target mRNAs of the DE miRNAs were related to testicular development and spermatogenesis. GO indicate that the target mRNAs were related to testicular development and spermatogenesis. KEGG indicate that pathways of target mRNAs enrichment related to testicular development, spermatogenesis, and energy metabolism. PROK2 was determined as the target mRNA of rno-miR-143-3p. Our study offers a basis for the regulatory mechanisms of miRNAs in testicular development and spermatogenesis in plateau zokor under reproductive suppression and offers a reference for reproductive regulation.

Livestock and subterranean mammals have contrasting impacts on soil infiltration of grasslands

The role of the increasing rodent population in grassland degradation on the Qinghai–Tibet Plateau (QTP) is the subject of continuing debate. We conducted a five-year grazing experiment to investigate the responses of soil permeability to livestock grazing and subterranean plateau zokor (Myospalax baileyi) burrowing activity in grasslands. In addition, using a meta-analysis approach, we generalized the effects of livestock grazing on soil permeability in global grasslands. The objective was to test the hypothesis that underground soil disturbance by burrowing mammals helps to improve the permeability of soil that has been compacted by trampling from grazing livestock. In the grazing experiment, soil saturated hydraulic conductivity (Ksat) in the upper 10 cm layer under livestock grazing (47.9 mm h−1) was less than one half of that under no grazing (116.8 mm h−1) in zokor-excluded plots. The Ksat value on zokor mounds (>two years old) (313.6 mm h−1) was eight times greater than that of inter-mound areas (38.5 mm h−1) in livestock-grazed plots. These contrasting effects on soil permeability of livestock grazing and subterranean zokor disturbance were ascribed to their opposite effects on soil macroporosity. Meta-analysis indicated that livestock grazing significantly decreased soil Ksat or steady infiltration rate in global grasslands by decreasing soil macroporosity, across grazing intensities, strategies, durations and climatic features, compared with no grazing. As such, the decreased soil permeability in grazed compared with non-grazed grasslands was a global generality. This research provided new insight into the ecohydrological function of subterranean mammals in pastures. The potential beneficial effects to soil permeability should be among the consideration for the management of subterranean mammals in grazed grasslands.

Reproductive Suppression Caused by Spermatogenic Arrest: Transcriptomic Evidence from a Non-Social Animal

Reproductive suppression is an adaptive strategy in animal reproduction. The mechanism of reproductive suppression has been studied in social animals, providing an essential basis for understanding the maintenance and development of population stability. However, little is known about it in solitary animals. The plateau zokor is a dominant, subterranean, solitary rodent in the Qinghai-Tibet Plateau. However, the mechanism of reproductive suppression in this animal is unknown. We perform morphological, hormonal, and transcriptomic assays on the testes of male plateau zokors in breeders, in non-breeders, and in the non-breeding season. We found that the testes of non-breeders are smaller in weight and have lower serum testosterone levels than those of breeders, and the mRNA expression levels of the anti-Müllerian hormone (AMH) and its transcription factors are significantly higher in non-breeder testes. Genes related to spermatogenesis are significantly downregulated in both meiotic and post-meiotic stages in non-breeders. Genes related to the meiotic cell cycle, spermatogenesis, flagellated sperm motility, fertilization, and sperm capacitation are significantly downregulated in non-breeders. Our data suggest that high levels of AMH may lead to low levels of testosterone, resulting in delayed testicular development, and physiological reproductive suppression in plateau zokor. This study enriches our understanding of reproductive suppression in solitary mammals and provides a basis for the optimization of managing this species.

Gut microbiota facilitates adaptation of the plateau zokor (Myospalax baileyi) to the plateau living environment.

Gut microbiota not only helps the hosts to perform many key physiological functions such as food digestion, energy harvesting and immune regulation, but also influences host ecology and facilitates adaptation of the host to extreme environments. Plateau zokors epitomize successful physiological adaptation to their living environment in the face of the harsh environment characterized by low temperature, low pressure and hypoxia in the Tibetan plateau region and high concentrations of CO2 in their burrows. Therefore, here we used a metagenomic sequencing approach to explore how gut microbiota contributed to the adaptive evolution of the plateau zokor on the Qinghai-Tibet Plateau. Our metagenomic results show that the gut microbiota of plateau zokors on the Tibetan plateau is not only enriched in a large number of species related to energy metabolism and production of short-chain fatty acids (SCFAs), but also significantly enriched the KO terms that involve carbohydrate uptake pathways, which well address energy uptake in plateau zokors while also reducing inflammatory responses due to low pressure, hypoxia and high CO2 concentrations. There was also a significant enrichment of tripeptidyl-peptidase II (TPPII) associated with antigen processing, apoptosis, DNA damage repair and cell division, which may facilitate the immune response and tissue damage repair in plateau zokors under extreme conditions. These results suggest that these gut microbiota and their metabolites together contribute to the physiological adaptation of plateau zokors, providing new insights into the contribution of the microbiome to the evolution of mammalian adaptation.

Soil microbial and macroinvertebrate functional diversity in response to Zokor disturbance in Tibetan alpine meadow

Soils contain a remarkable diversity of organisms that are important regulators of ecosystem functions. However, the knowledge of how the environment shapes biodiversity patterns below ground remains limited in alpine areas of the Tibetan Plateau. Here, we conducted a microhabitat scale study (400 m2 plot) integrating data on soil and plant community characteristics to explore the driving forces of functional diversity of soil microbial and macroinvertebrate communities under disturbance by plateau zokor (Eospalax baileyi), a subterranean rodent inhabiting the Tibetan Plateau. The results show that plateau zokor disturbance led to a decline in the belowground biomass of grasses, whereupon the total belowground plant biomass and soil organic carbon decreased significantly. The functional diversity of soil microbial and macroinvertebrate communities was significantly increased under plateau zokor disturbance. Redundancy analysis indicated that soil moisture, temperature and compaction, in combination with plant species richness and belowground biomass of forb were the most important factors in driving soil microbial and macroinvertebrate functional diversity. Piecewise structural equation modeling (SEM) revealed that plateau zokor mound disturbance had positive effects on the functional diversity of soil microbial and macroinvertebrate communities by regulating soil physical properties (moisture, temperature, and compaction) and plant species richness within the habitat. Further, zokor disturbance affected the functional diversity of soil microbial and macroinvertebrate communities indirectly via regulating soil organic carbon. Our study provides evidence that the functional diversity of microbes is more driven by environmental changes than those of macroinvertebrates.

A Comparative Study on the Distribution Pattern of Endocrine Cells in the Gastrointestinal Tract of Two Small Alpine Mammals, Plateau Zokor (Eospalax baileyi) and Plateau Pika (Ochotona curzoniae)

Endocrine cells can secrete a variety of gastrointestinal hormones that regulate gastrointestinal digestion and absorption, which, in turn, play an important role in animal growth, metabolism, and acclimation. The small alpine mammals, plateau zokor (Eospalax baileyi) and plateau pika (Ochotona curzoniae), live in a unique ecotope with cold, hypoxic environments and short plant-growing seasons, resulting in differential adaptive digestive strategies for foods. Studying the distribution pattern of endocrine cells in the gastrointestinal tract (GIT) of these two animals can lead to a better understanding of the survival strategies of animals in an alpine environment. In this study, we used histochemical and immunohistochemical methods to compare the distribution pattern of argyrophilic cells and the expression of 5-HT cells, Gas cells, and Glu cells in the GIT of the plateau zokor with those of the plateau pika. The results showed that these endocrine cells we studied were widely distributed in the gastrointestinal organs of both these small mammals, and their morphology and distribution location in the GIT were almost the same. However, there were significant differences in the distribution density of argyrophilic cells between different organs in the GIT. The distribution density of argyrophilic cells in the duodenum, jejunum, ileum, and rectum of plateau zokor was significantly lower than that of plateau pika (p < 0.05) and, in the cecum of plateau zokor, was significantly higher than that of plateau pika (p < 0.001). The positive expression of 5-HT cells in the corpus I, corpus II, and pylorus of the stomach, duodenum, ileum, and rectum of plateau zokor was significantly higher than that of plateau pika (p < 0.01). In addition, the positive expression of Glu cells in the cecum was significantly higher (p < 0.01) and in the duodenum and colon was significantly lower (p < 0.05) in the plateau zokor than in the plateau pika. We conclude that the distribution pattern of endocrine cells in the GIT is consistent with the respective animals' diets, with the plateau zokor feeding on high-fiber roots and plateau pika preferring to intake the aboveground parts of plants with lower fibers.

Seismic Signaling for Detection of Empty Tunnels in the Plateau Zokor, Eospalax baileyi.

There are considerable challenges involved in studying the behavior of subterranean rodents owing to the underground nature of their ecotope. Seismic communication plays a crucial role in the behavior of subterranean rodents, particularly solitary ones. The plateau zokor (Eospalax baileyi), a solitary subterranean rodent species endemic to the Qinghai-Tibet Plateau, will usually occupy empty neighboring tunnels in order to extend their territory. Little is known, however, about the process of territorial occupation or the function of animal communication when occupation is taking place. Based on previous studies of subterranean rodent communication, we hypothesized that plateau zokors use seismic signals to detect neighboring tunnels and then occupy them when it was found their neighbors were absent. To test this, we placed artificial tunnels close to active original zokor tunnels to simulate the availability of an empty neighboring tunnel, and then the seismic signals when a zokor chose to occupy the empty artificial tunnel were recorded. The results showed that the frequency of zokors occupying artificial empty tunnels within 48 h was 7/8, In all of these instances, the zokors generated seismic signals before and after occupation of the empty artificial tunnel. The number of seismic signals generated by the zokors increased significantly (p = 0.024) when they detected and occupied the artificial tunnels, compared to those generated in their original tunnels without the presence of an artificial tunnel alongside. Inside the original tunnels, the inter-pulse time interval of the seismic signals was significantly higher (p &lt; 0.001), the peak frequency of these signals was significantly higher (p &lt; 0.01), and the energy of the signals was significantly lower (p = 0.006), compared with those when an artificial tunnel was positioned next to the original. The results of this study suggest that plateau zokors first generate seismic signals to detect empty neighboring tunnels and that they are empty. In the absence of neighbor plateau zokors, they occupy the empty tunnels to extend their own territory.

高原鼠兔和高原鼢鼠种群暴发区干扰斑块空间分布格局与演替规律

PDF HTML阅读 XML下载 导出引用 引用提醒 高原鼠兔和高原鼢鼠种群暴发区干扰斑块空间分布格局与演替规律 DOI: 10.5846/stxb202204161021 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31872999，U21A20191）；青海省科学技术厅项目（2020-ZJ-904）；高等学校学科创新引智计划（D18013） Spatial distribution pattern and succession of disturbance patches formed by plateau pika and plateau zokor in their population outbreak areas in alpine meadow Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:高原鼠兔（Ochotona curzoniae）和高原鼢鼠（Myospalax baileyi）是两种在高寒草甸广泛分布的小型哺乳动物，其暴发活动可能造成高寒草甸的严重退化。使用无人机分别拍摄典型的高原鼠兔和高原鼢鼠种群暴发区图像，解译高原鼠兔洞口、高原鼢鼠土丘和它们的干扰斑块，获得干扰斑块的周长和面积信息，计算干扰斑块形状指标，确定高原鼠兔与高原鼢鼠暴发活动对高寒草甸的影响。研究表明：（1）高原鼠兔与高原鼢鼠暴发活动形成的干扰斑块周长与面积比（PARA）、形状指数（SHAPE）和分形维数（FRAC）差异显著（P<0.05），其中高原鼢鼠斑块的FRAC是1.0124±0.0091，属于普通的规则几何圆形分布格局，高原鼠兔斑块的FRAC是1.1203±0.0546，属于分形几何不规则的分布格局。（2）高原鼠兔洞口数量与其斑块面积没有线性相关关系（P=0.9677），高原鼢鼠土丘数量与其斑块面积呈显著正相关（P<0.05）。（3）高原鼢鼠斑块面积统计学上呈长尾分布，不符合正态分布（P<0.01）。根据高原鼠兔斑块面积分布格局可将斑块演替分为三个阶段：土丘形成阶段、斑块连通阶段和斑块扩散阶段。高原鼠兔土丘形成阶段斑块的形状和分布，与高原鼢鼠干扰斑块相似；在演替初期阶段融合连通阶段斑块的面积分布呈指数分布，形状趋于分形几何（FRAC=1.1161）；在跨尺度扩散阶段斑块面积较大且形状复杂（SHAPE=4.4202），呈现不规则分布格局。三个阶段斑块的周长与面积比、形状指数和分形维数差异显著（P<0.05）。高原鼠兔在退化高寒草甸的觅食活动促进了融合连通阶段斑块的形成，呈现分形几何斑块演替规律。由此得出结论，引起高寒草甸退化的主要原因是过度放牧下高原鼠兔暴发活动，造成跨尺度扩散斑块演替阶段出现的结果，并非高原鼢鼠的暴发活动形成的。因此，控制高原鼠兔数量并恢复高原鼠兔干扰斑块植被相比高原鼢鼠更重要。 Abstract:Plateau pika (Ochotona curzoniae) and plateau zokor (Myospalax baileyi) are two species of small mammal widely distributed in alpine meadow. The main difference between the two animals is that plateau zokor mainly lives underground and plateau pika mainly lives on the surface of grassland. Their outbreak activities may cause serious degradation of alpine meadow. The disturbance patches formed by the two animals have different effects on the alpine meadow. Which kind of animal outbreak can lead to the cross-scale succession of disturbance patches is a scientific problem that needs to be solved. The patch shape and pattern metric in the field of landscape ecology can be used to compare the patch distribution patterns, thereby understanding the differences in the formation process of various patches. In this study, Unmanned aerial vehicle (UAVs) were used to capture typical images of plateau pika and plateau zokor population outbreak areas. Plateau pika holes, plateau zokor mounds and their disturbance patches were interpreted. The perimeter and area information of the disturbance patch was obtained. The shape and pattern metrics of disturbance patch were calculated and analyzed. The effects of outbreak activities of plateau pika and plateau zokor on the degradation of alpine meadow were determined. The results indicated that (1) there were significant differences in perimeter-area ratio (PARA), shape index (SHAPE) and fractal dimension index (FRAC) between plateau pika and plateau zokor disturbance patches formed by their outbreak activities (P<0.05). The FRAC of plateau zokor patches was 1.0132±0.0103, which belongs to ordinary regular geometry (circle), and the FRAC of plateau pika patches was 1.1007±0.0576, which belongs to fractal geometry. (2) There was no correlation between the number of plateau pika holes and the patch area of plateau pika (P=0.9677). There was a significantly positive correlation between the number of mounds and the patch area of plateau zokor (P<0.05). (3) The area of plateau zokor patch showed a long tail distribution at statistics, which did not accord with the normal distribution (P<0.01). According to the patch distribution pattern of plateau pika, the succession of patches could be divided into three stages:mound stage, fusion stage and broad-scale stage. The shape and distribution pattern of patches at the mound stage were similar to those of plateau zokor patches. At the fusion stage, the patch distribution was exponential, and the shape and pattern belonged to fractal geometry (FRAC=1.1161). At the broad-scale stage, the patch pattern was large and the shape was complex (SHAPE=4.4202). The patches at the broad-scale stage were formed by the connection between the surrounding fusion stage patches and the core area of black soil degraded patches, which destroyed the dynamic balance between disturbance and restoration of alpine meadow. There were significant differences among PARA, SHAPE and FRAC at the three stages (P<0.05). The foraging activities of plateau pika in the degradation of alpine meadow promoted the formation of patches and formed fractal geometric patches at the fusion stage. The main cross-scale interaction resulting in the degradation of alpine meadow was caused by the outbreak of plateau pika, not plateau zokor. Therefore, it is more important to control the number of plateau pika and restore the disturbance patches of plateau pika than those of plateau zokor. 参考文献 相似文献 引证文献

Effects of Inhabiting and Life Patterns on the UV Spectral Properties of Small Mammalian Herbivores’ Urine

It is well known that avian predators can use prey excretions such as urine and feces to track their prey, and the urine and feces of small mammalian herbivores can reflect ultraviolet (UV) light and emit fluorescent light. There are still some debates as to whether UV visibility of small mammalian herbivores’ urine is used as a hunting cue by avian raptors. Some studies in Europe have demonstrated that diurnal raptors are capable of utilizing these cues to target key prey species. However, researchers in Australia have argued that raptors do not use the UV visibility of urine while hunting. To our knowledge, there are no reports from Asia concerning the ultraviolet spectral characteristics of small mammal herbivores’ urine. This study examined the UV spectral properties of urine from 6 small mammal herbivores species by comparing the UV reflectance and fluorescence spectra of urine from small mammalian herbivores living in plateau meadows, plateau shrubs, open marshland, farmland, and semi-desert grassland in China. In addition, we compared the UV spectral properties of urine from ground-dwelling species of rodents and subterranean species to determine whether ultraviolet visibility of small mammal herbivores’ urine could be used as a visual signal by Asian vole-eating raptors. The results showed that: 1) the SC370 values of urine from four small mammal herbivores species were ordered as plateau pika (plateau meadow) > root voles (plateau bush) > reed voles (swampland) > Brandt’s vole (desert grassland); and 2) UV fluorescence peak intensity and the wavelengths of urine from ground-dwelling species (such as the root vole, plateau pika, or Brandt’s vole) were significantly higher than those of subterranean-dwelling species (mandarin vole and plateau zokor). These results indicate that UV visibility of small mammal herbivores’ urine may act as a visual cue for raptors.

Dynamic changes in the home range of the subterranean rodent Myospalax baileyi

As ecosystem engineers, subterranean rodents excavate and inhabit burrow systems. However, the changes in their use of underground space are poorly recorded. There is conflicting evidence about whether the burrow systems of subterranean rodents, once established, are relatively stable as a result of the high energy costs of digging. We monitored the size of the home ranges of the plateau zokor (Myospalax baileyi) during different stages of its life cycle to show whether mating behavior and the characteristics of its habitat influence the size and location of its home range. We used radio-tracking to quantify the changes in, and overlap of, the home range ofM. baileyiduring a one-year period. The average size of the home ranges of male zokors was 6.5 times larger than that of female zokors during the mating season. The males expanded their burrows to overlap with multiple females to increase their chances of mating. However, there was no overlap between estrus females or males, perhaps to reduce the number of encounters and unnecessary fights. The home ranges of male and female zokors were similar in size after courtship and the home ranges of single zokors overlapped with those of several neighbors. Most individuals remained territorial and excluded intraspecific interactions from their home ranges. The location of female zokors was stable throughout the year, but half of the males changed the location of their nests and established completely new home ranges in the non-breeding season, mainly in October. The use of space byM. baileyiis flexible in response to a need for physical contact during the mating season and food resources. The home ranges of subterranean plateau zokors are dynamic and the home ranges of male zokors can change within one breeding cycle.