PIKA佐剂在体内外诱导小鼠免疫应答的探讨

目的探讨PIKA佐剂在体内外诱导小鼠的免疫应答。方法体外将小鼠脾淋巴细胞与不同浓度PIKA佐剂培养后,ELISA检测细胞因子IFN-γ、IL-12p40的产生,FACS检测细胞的增殖及活化。体内将PIKA佐剂经小鼠腹腔注射后,检测不同时间点血清中IFN-γ、IL-12p40、IL-6、TNF-α等细胞因子的产生。结果PIKA佐剂体外呈剂量依赖性诱导小鼠脾细胞产生IFN-γ和IL-12p40。细胞亚群分析的结果表明,PIKA可显著刺激B细胞和NK细胞活化、增殖。体内注射PIKA佐剂后可诱导细胞因子IFN-γ、IL-12p40、IL-6、TNF-α的产生,但产生的时间点不同。结论PIKA佐剂体内外直接通过诱导细胞因子的产生,B细胞和NK细胞的活化和增殖,而促进免疫应答反应。

Genomics and morphometrics reveal the adaptive evolution of pikas

Pikas(Lagomorpha: Ochotonidae) are small mouselike lagomorphs. To investigate their adaptation to different ecological environments during their dispersal from the Qinghai-Xizang(Tibet) Plateau(QTP), we collected 226 pikas and measured 20 morphological characteristics and recorded habitat information. We also sequenced the genome of 81specimens, representing 27 putative pika species.The genome-wide tree based on 4?090 coding genes identified five subgenera, i.e., Alienauroa, Conothoa,Lagotona, Ochotona, and Pika, consistent with morphometric data. Morphologically, Alienauroa and Ochotona had similar traits, including smaller size and earlier divergence time compared to other pikas.Consistently, the habitats of Alienauroa and Ochotona differed from those of the remaining subgenera. Phylogenetic signal analysis detected 83 genes significantly related to morphological characteristics, including several visual and hearingrelated genes. Analysis of shared amino acid substitutions and positively selected genes(PSGs) in Alienauroa and Ochotona identified two genes, i.e.,mitochondrial function-related TSFM(p.Q155E) and low-light visual sensitivity-related PROM1(p.H419Y).Functional experiments demonstrated that TSFM-155E significantly enhanced mitochondrial function compared to TSFM-155Q in other pikas, and PROM1-419Y decreased the modeling of dynamic intracellular chloride efflux upon calcium uptake. Alienauroa and Ochotona individuals mostly inhabit different environments(e.g., subtropical forests) than other pikas, suggesting that a shift from the larger ancestral type and changes in sensory acuity and energy enhancement may have been required in their new environments. This study increases our understanding of the evolutionary history of pikas.

Influences of pika and simulated grazing disturbances on bare patches of alpine meadow in the Yellow River Source Zone

Bare patches in alpine meadow are the main manifestation of its degradation.The change of bare patches in an alpine meadow in the Yellow River Source Zone during 2018-2019 was studied in relation to the disturbances caused by plateau pika(Ochotona curzoniae)population and simulated grazing via artificial mowing both independently and interactively.The disturbance was set at three levels of high,medium and no disturbance(control group).Bare patches were mapped by from unmanned aerial vehicle(UAV)images with fine resolution of 1 cm obtained in August 2018 and August 2019 in ArcGIS.The results showed that the total area of bare patches decreased by 112.05 m2 in sub-plots devoid of pika disturbance but increased by 126.37 m2 in other subplots.The highest rate of increase is 89.02%.The individual effect of pika exceeds the joint effect of pika and mowing disturbances.The sole effect of mowing is lower than the joint effect of pika disturbance and intensive mowing,but higher than the joint influence of pika disturbance and moderate mowing.Strong pika disturbance(14 per sub-plot)caused the influence of mowing from moderate to intensive to increase by five-fold.The area of bare patches treated with moderate mowing and no pika disturbance decreased at the highest pace(-37.22%).Intensive mowing and medium density pikas(100 pikas/ha)are considered the thresholds at which the bare patches start to expand.Even if the meadow is mowed at the medium and high intensity,the area of bare patches can be significantly reduced if plateau pika population is controlled to a low level.ANOVA analysis and longterm macro-scale satellite-derived results reveal that pika disturbance is more important in causing the bare patches to change than simulated grazing.Therefore,it is more important to control the number of pikas than to reduce grazing intensity to prevent the expansion of bare patches in the degraded alpine meadow in the study area.

Escherichia coli Expression of Lactate Dehydrogenase C Gene of Black-Lipped Pika in Western Sichuan Plateau

[ Objective] To express lactate dehydrogenase C （LDH-C） gene in prokaryotic system and then purify the recombinant protein. E Meth- od] The LDI-I-C gene was amplified from black-lipped pika（ Ochotona curzoniae） by RT-PCR and ligated to the expression vector pET-32a. The E. coli BL21 （DE3） carrying the LDI-I-C gene was obtained and induced by IPTG （isopropy-beta-D-thiogalactoside）. The expression products were analyzed by SDS-PAGE and purified by affinity chromatography. L Result] An approximately 1.0 kbp band appeared in the RT-PCR products as the- oretically expected. As evidenced by PCR and double enzyme digestion, an approximately 1.0 kbp fragment appeared, which indicated successful construction of expression vector. As analyzed by SDS-PAGE, a fusion protein with molecular weight slightly larger than 45 kDa was expressed in form of inclusion body. And very pure fusion protein was obtained by nickel ions-charged affinity chromatography. [ Coaclusion] The LDH-C gene of black-lipped pika has been cloned and expressed in E. coil

The Influence of Fence on Body Mass and Population Dynamics of Plateau Pika

To determine the influence of the fence on plateau pika (Ochotona curzoniae), we measured the body mass, breeding status, population densities, using live-trapping and line-transect sampling in April and September 2006. In April, body mass of both male and female plateau pika inside of fence were significant higher than that outside of fence (♀: F = 6.583, df = 1.20, p = 0.019;♂: F = 6.49, df = 1.17, p = 0.021). The ratio of spermary drop of an adult male was also higher (92.31% vs 57.14%). In September, body mass of adult male in both study sites showed no significant difference (F = 0.001, df = 1.23, p = 0.975), but were all significant higher than that of April (F = 121.713, df = 1.22, p < 0.001;F = 105.819, df = 1.20, p < 0.001). In April, the population densities of both study sites showed on significant difference (F = 2.388, df = 1.38, p = 0.131), but the population density inside of fence was much higher than that outside of fence (F = 7.534, df = 1.38, p = 0.009) in September. Our results show that the changes of quality and quantity of food that available to plateau pika in winter, can depress the range of reducing body mass of plateau pika, make breeding season ahead, and then promote the increase of population.

THE PIKA IS OUR FRIEND

Soon a furry-faced head with bright eyes and rounded ears will pop up and peer out.You are meeting the plateau pika. Its Tibetan name is abra and its scientific name Ochotona curzoniae.

Soil Erosion and Vegetation Succession in Alpine Kobresia Steppe Meadow Caused by Plateau Pika——A Case Study of Nagqu County, Tibet

This paper evaluated the impacts of mounds created by the plateau pika (Ochotona curzoniae) on the vege- tation composition, structure, and species diversity of an alpine Kobresia steppe meadow in Nagqu County, Tibet Autonomous Region, China. Based on mound height or the depth of erosion pit, we defined five stages of erosion and compared the floristic features of communities at these stages with those in undisturbed sites. In the study area, the mounds and pits covered up to 7% of the total area. Lancea tibetica, Lamiophlomis rotata, and Potentilla bifurca were the dominant species in erosion pits, and Kobresia pygmaea, the dominant species in undisturbed sites, became a com- panion species in eroded areas. In the process of erosion, the original vegetation was covered by soil ejected by the pika, then the mounds were gradually eroded by wind and rain, and finally erosion pits formed. The vegetation coverage in- creased with increasing erosion stages but remained significantly lower than that in undisturbed sites. Improved coverage eventually reduced soil erosion, and pit depth eventually stabilized at around 20cm. Aboveground biomass increased with increasing erosion stage, but the proportion of low-quality forage reached more than 94%. The richness index and Shannon-Wiener index increased significantly with increasing erosion stage, but the richness index in mound and pit areas was significantly lower than that in undisturbed sites.

PIKA Provides an Adjuvant Effect to Induce Strong Mucosal and Systemic Humoral Immunity Against SARS-CoV

Severe Acute Respiratory Syndrome(SARS) is a deadly infectious disease caused by SARS Coronavirus(SARS-CoV).Inactivated SARS-CoV has been explored as a vaccine against SARS-CoV.However,safe and potent adjuvants,especially with more efficient and economical needle-free vaccination are always needed more urgently in a pandemic.The development of a safe and effective mucosal adjuvant and vaccine for prevention of emergent infectious diseases such as SARS will be an important advancement.PIKA,a stabilized derivative of Poly(I:C),was previously reported to be safe and potent as adjuvant in mouse models.In the present study,we demonstrated that the intraperitoneal and intranasal co-administration of inactivated SARS-CoV vaccine together with this improved Poly(I:C) derivative induced strong anti-SARS-CoV mucosal and systemic humoral immune responses with neutralizing activity against pseudotyped virus.Although intraperitoneal immunization of inactivated SARS-CoV vaccine alone could induce a certain level of neutralizing activity in serum as well as in mucosal sites,co-administration of inactivated SARS-CoV vaccine with PIKA as adjuvant could induce a much higher neutralizing activity.When intranasal immunization was used,PIKA was obligatorily for inducing neutralizing activity in serum as well as in mucosal sites and was correlated with both mucosal IgA and mucosal IgG response.Overall,PIKA could be a good mucosal adjuvant candidate for inactivated SARS-CoV vaccine for use in possible future pandemic.

Altitude-dependent metabolite biomarkers reveal the mechanism of plateau pika adaptation to high altitudes

The harsh environment in the Tibetan plateau,the highest place in the world,poses thermoregulatory challenges and hypoxic stress to animals.The impacts of plateau environment on animal physiology and reproduction include external factors such as strong ultraviolet radiation and low temperature,and internal factors such as animal metabolites and gut microbiota.However,it remains unclear how plateau pika adapt to high altitudes through the combination of serum metabolites and gut microbiota.To this end,we captured 24 wild plateau pikas at the altitudes of 3400,3600,or 3800 m a.s.l.in a Tibetan alpine grassland.Using the machine learning algorithms(random forest),we identified five biomarkers of serum metabolites indicative of the altitudes,that is,dihydrotestosterone,homo-l-arginine,alpha-ketoglutaric-acid,serotonin,and threonine,which were related to body weight,reproduction,and energy metabolism of pika.Those metabolic biomarkers were positively correlated with Lachnospiraceae_Agathobacter,Ruminococcaceae,or Prevotellaceae_Prevotella,suggesting the close relationship between metabolites and gut microbiota.By identifying the metabolic biomarkers and gut microbiota analysis,we reveal the mechanisms of adaptation to high altitudes in plateau pika.

Plateau pikas near roads are bold and silent when facing a potential predator

Human disturbance,particularly road traffic,is one of the greatest threats to wildlife.Considering the association between alerting behavior and the survival of animals,it is important to study the effects of road traffic on alerting behavior of wildlife.Previous studies assessing the shortterm impact of road traffic on alerting behavior of wildlife have focused on vigilance distances.However,studies on the use of alarm calls are scarce,and it is unclear whether such behavioral responses change after repeated exposure to road traffic.We assessed the alerting behavior of plateau pikas(Ochotona curzoniae)who were near or far from roads when facing a potential predator.We found that pikas near roads exhibited shorter vigilance and tolerance distances,and produced fewer alarm calls than those relatively far away from roads.Furthermore,both vigilance and tolerance distances of plateau pikas were significantly positively correlated with the distance from the burrow to the road.Road traffic reduced antipredator responses and shaped alerting behavior;that is,pikas near roads were bolder and more silent compared to those far away from roads.Our findings suggest that increasing urbanization will have corresponding effects on animal behavior,which may have significant fitness effects in the future.

The genomic characteristics and pathogenicity of a mammalian orthoreovirus within a new lineage from wild pika in plateau

Emerging and re-emerging viruses from wild animals have seriously threatened the health of humans and domesticated animals in recent years.Herein,we isolated a new mammalian orthoreovirus(MRV),Pika/MRV/GCCDC7/2019(PMRV-GCCDC7),in the Qinghai-Tibet Plateau wild pika(Ochotona curzoniae).Though the PMRVGCCDC7 shows features of a typical reovirus with ten gene segments arranged in 3:3:4 in length,the virus belongs to an independent evolutionary branch compared to other MRVs based on phylogenetic tree analysis.The results of cellular susceptibility,species tropism,and replication kinetics of PMRV-GCCDC7 indicated the virus could infect four human cell lines(A549,Huh7,HCT,and LoVo)and six non-human cell lines,including Vero-E6,LLCMK2,BHK-21,N2a,MDCK,and RfKT cell,derived from diverse mammals,i.e.monkey,mice,canine and bat,which revealed the potential of PMRV-GCCDC7 to infect a variety of hosts.Infection of BALB/c mice with PMRVGCCDC7 via intranasal inoculation led to relative weight loss,lung tissue damage and inflammation with the increase of virus titer,but no serious respiratory symptoms and death occurred.The characterization of the new reovirus from a plateau-based wild animal has expanded our knowledge of the host range of MRV and provided insight into its risk of trans-species transmission and zoonotic diseases.

不同干扰强度高原鼠兔对高寒草甸土壤温室气体通量变化的影响

高原鼠兔通过取食植物、排泄粪尿及掘土等行为对土壤理化性质及土壤微生物产生广泛干扰,进而可能会影响高寒草甸土壤温室气体排放。本研究选择高密度组(H)、低密度组(L)、对照组(CK)3种鼠兔干扰强度的高寒草甸为研究对象,揭示温室气体排放速率对不同高原鼠兔干扰强度的响应规律及主要调控因素。结果表明,H组高寒草甸土壤CO_(2)排放速率为596.66 mg·(m^(2)·h)^(-1),显著低于CK组的695.45 mg·(m^(2)·h)^(-1)(P<0.05)。高原鼠兔干扰强度、地上生物量、土壤pH和土壤含水量是影响CO_(2)排放速率的主要调控因素。H组高寒草甸CH_(4)吸收速率为-43.46mg·(m^(2)·h)^(-1),显著低于L组的4.92mg·(m^(2)·h)^(-1)(P<0.05),H和L组高寒草甸N_(2)O排放速率分别为8.03、-2.39μg·(m^(2)·h)^(-1),均显著高于CK组的-16.69μg·(m^(2)·h)^(-1)(P<0.05)。土壤硝态氮和铵态氮含量、pH和含水量是影响CH_(4)吸收和N_(2)O排放的重要因素。因此,高原鼠兔干扰强度是影响温室气体排放速率的因素之一,进一步研究高原鼠兔对高寒草甸土壤温室气体排放速率的影响具有重要意义。

PIKA as an Adjuvant Enhances Specific Humoral and Cellular Immune Responses Following the Vaccination of Mice with HBsAg plus PIKA

An adjuvant is usually used to enhance the immune response induced by vaccines. The choice of adjuvant or immune enhancer determines the effectiveness of the immune response. Currently, aluminium （Alum, a generic term for salts of aluminium） is the only FDA-approved adjuvant. Alum predominantly induces the differentiation of Th2 cells and thus mediates an antibody immune response. Therefore, there is an urgent need for new adjuvants that enhance not only humoral but also cellular immune responses. In the present study, we demonstrates that PIKA （a stabilized dsRNA） as an adjuvant directly induces the activation and the proliferation of both B and NK cells in vitro. Injection of PIKA into mice results in the production of cytokines in vivo. In addition, the study demonstrates that PIKA promotes the maturation of bone marrow-derived dendritic cells （BMDCs） including up-regulation of the co-stimulatory molecules CD80, CD86 and CD40, and the induction of cytokines such as IL-12p70, IL-12p40 and IL-6. Importantly, after immunization of mice with HBsAg plus PIKA, the presence of PIKA enhances the titers of HBsAg-specific IgG and HBsAg-specific IFN-γ production. These results demonstrate that PIKA as an adjuvant can promote both humoral and cellular immune responses. These might have an implication in applying PIKA as an adjuvant to be used in the design and development of both therapeutic and preventive vaccines, and used in the clinical study.

Seasonal variations in the composition and functional profiles of gut microbiota reflect dietary changes in plateau pikas

Seasonal variations in gut microbiota of small mammals and how they are influenced by environmental variables are relatively poorly understood.We sampled 162 wild plateau pikas(Ochotona curzoniae)in 4 seasons over 2 and a half years and recorded the air temperature,precipitation,and nutrient content in edible vegetation at the sampling site.After conducting 16S rRNA and shotgun metagenomic sequencing,we found that the highest alpha diversity,the relative abundance of Firmicutes,and the simplest co-occurrence network occurred in winter,whereas the highest relative abundance of Proteobacteria and the most complex network structure were observed in spring.The highest relative abundance of Verrucomicrobiota and Spirochaetota was seen in summer and autumn,respectively.Air temperature,precipitation,and the contents of crude protein,crude fiber,and polysaccharide in vegetation had significant effects on the seasonal changes in gut microbiota.Diet contributed more to microbial variation than climatic factors.Metagenomic analysis revealed that the amino acid metabolism pathway and axillary activity enzymes were most abundant in summer,while abundance of carbohydrate-binding modules and carbohydrate esterases was highest in spring.These microbial variations were related to the changes in dietary nutrition,indicating that gut microbiota of plateau pika contribute to the efficient use of food resources.This study provides new evidence of how external environmental factors affect the intestinal environment of small mammals.

The plateau pika has multiple benefits for alpine grassland ecosystem in Qinghai–Tibet Plateau

The plateau pika(Ochotona curzoniae)has been engaged in pest control for many years based on the logic that the plateau pika is responsible for alpine grassland degradation and competes with livestock for forage resources.However,the plateau pika is an important species which has multiple benefits in Qinghai-Tibetan Plateau,as it(i)makes burrows that are the primary homes for lizards and a variety of small birds;(ii)creates microhabitat disturbance that promotes the increase of plant species richness;(iii)serves as the principal prey for almost all of the plateau predator species;and(iv)contributes positively to the dynamic equilibriumof alpine ecosystems.

Evolution for extreme living:variation in mitochondrial cytochrome c oxidase genes correlated with elevation in pikas(genus Ochotona)

The genus Ochotona(pikas)is a clade of cold-tolerant lagomorphs that includes many high-elevation species.Pikas offer a unique opportunity to study adaptations and potential limitations of an ecologically important mammal to high-elevation hypoxia.We analyzed the evolution of 3 mitochondrial genes encoding the catalytic core of cytochrome c oxidase(COX)in 10 pika species occupying elevations from sea level to 5000 m.COX is an enzyme highly reliant on oxygen and essential for cell function.One amino acid property,the equilibrium constant(ionization of COOH),was found to be under selection in the overall protein complex.We observed a strong relationship between the net value change in this property and the elevation each species occupies,with higher-elevation species having potentially more efficient proteins.We also found evidence of selection in low-elevation species for potentially less efficient COX,perhaps trading efficiency for heat production in the absence of hypoxia.Our results suggest that different pika species may have evolved elevation-specific COX proteins,specialization that may indicate limitations in their ability to shift their elevational ranges in response to future climate change.

Brief report on the status of Kozlov’s pika,Ochotona koslowi(Büchner),in the east Kunlun mountains of China

Koslov’s pika,Ochotona koslowi(Büchner),was surveyed in western China.This endangered species is poorly known.We determined that it is a burrowing pika,and lives in social family groups at high densities.It primarily occupies high-elevation cold grassland vegetation.It appears to have a high reproductive rate.More emphasis should be placed on research into this unique species in China.

高原鼠兔干扰与高寒草甸退化的时空耦合关系

[目的]高原鼠兔是青藏高原高寒草甸生态系统的关键物种。分析鼠兔活动与草甸退化之间的耦合关系,为进一步完善高原鼠兔干扰强度观测体系,提供更加全面、科学的鼠兔活动调查数据。[方法]本研究利用无人机对地观测与深度学习构建了一种鼠兔干扰强度观测与分级方法,并利用景观指数和耦合度模型开展了时空变化分析。[结果](1)ResNet-101残差网络模型提取鼠丘秃斑的精度可达92.7%。2019年研究区鼠兔干扰微度和轻度面积占总面积的82.0%,2021年中度及以上干扰强度占62.5%。2019—2021年鼠兔干扰明显、显著和极度增强的面积占43.0%。(2)2019,2021年高寒草甸植被均以中度退化为主,2019—2021年中度退化转变为重度退化的面积占30.2%,植被覆盖度出现显著降低的面积占7.7%。(3)研究区景观以单一方向变化为秃斑,景观类型向更加聚集、规则、单一化的方向转变,秃斑景观的优势度显著上升。(4)2019—2021年研究区大部分区域的耦合度增加,鼠兔干扰与高寒草甸间的相互作用增强。[结论]研究区高原鼠兔干扰强度显著变大,植被覆盖度降低,景观逐步向秃斑类型转变,高寒草甸在高原鼠兔干扰下退化趋势明显,二者的耦合作用逐步增强,有必要采取更加积极的防治、恢复措施。

高原鼠兔干扰对高寒草甸植物物种多样性与土壤生态化学计量比间关系的影响

植物物种多样性和土壤生态化学计量比间的关系,是草地植物群落结构维持的关键。高原鼠兔干扰虽被证实能够影响植物物种多样性、土壤有机碳、全氮和全磷的含量,但是否影响高寒草甸植物物种多样性和土壤生态化学计量比间的关系,尚不清楚。本研究以甘南和青海湖流域为对象,采用配对设置样地的方法,分析了高原鼠兔干扰对高寒草甸植物物种多样性和土壤生态化学计量比间关系的影响。结果表明:高原鼠兔干扰显著增加了物种丰富度指数、土壤有机碳、全氮和全磷含量,以及土壤C∶N和C∶P(P<0.05),但没有显著影响物种多样性指数、物种均匀度指数和土壤N∶P。高原鼠兔干扰增加了物种丰富度指数和物种多样性指数与土壤C∶N间的正相关性(P<0.05),减弱了物种丰富度指数与土壤C∶P间的正相关性(P<0.01);物种多样性指数与土壤C∶P间的关系从高原鼠兔未干扰生境的对数关系转变为干扰生境的二次函数关系(P<0.05),而物种丰富度指数与土壤N∶P间的关系从高原鼠兔未干扰生境的不显著相关,改变为干扰生境的显著负相关二次函数(P<0.01);物种多样性指数与土壤N∶P间的关系从未干扰生境的显著正相关二次函数(P<0.05),变为干扰生境的不显著相关,这确证了高原鼠兔干扰能够改变植物物种多样性与土壤生态化学计量比间的关系,为全面解释高原鼠兔干扰下草地植物群落结构的维持提供了基础信息。

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

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。