蓖麻粗毒的获取及草原灭鼠的应用研究

本研究修改了蓖麻脱脂方法,获取蓖麻种子的粗毒,进而研究了粗毒的灭鼠功效。蓖麻粗毒对小鼠灌胃实验测得LD50为11．494mg／kg。实验室有毒饵料饲喂小鼠结果显示,小鼠对蓖麻粗毒混合饵料无明显拒食现象。野外实验结果显示,粗毒饵料对高原鼠兔的灭洞率在81．6％到90．1％之间。研究结果表明蓖麻粗毒具有很好的应用于生物防治的潜力。     

高原鼠兔脑组织中精子特异性乳酸脱氢酶的作用

高原鼠兔对高原低氧环境有很强的适应性。研究发现,精子特异性乳酸脱氢酶(LDH-C4)基因在高原鼠兔脑组织中表达,为阐明LDH-C4在高原鼠兔脑组织中的作用,应用荧光定量PCR和Western blot方法,测定了Ldh-c基因在高原鼠兔脑组织中的表达水平;应用对精子特异性乳酸脱氢酶(LDH-C4)特异性的抑制剂(N-isopropyl oxamate),通过肌肉注射后,研究抑制剂对高原鼠兔脑组织中LDH比活力、乳酸和ATP含量的影响。结果表明,在mRNA和蛋白水平,Ldh-c基因在高原鼠兔脑组织中均有表达,相对表达水平分别为0.38±0.05和0.74±0.13;当肌肉注射1 m L 1 mol/L的抑制剂30 min后,血液中抑制剂浓度为0.08 mmol/L;与对照组相比,抑制剂组脑组织中LDH比活力、乳酸和ATP含量显著下降,抑制剂对LDH、乳酸和ATP的抑制率分别为30.78%、46.47%和21.04%。结果表明,精子特异性乳酸脱氢酶基因在高原鼠兔脑组织中表达。LDH-C4通过催化无氧糖酵解过程,为其脑组织生命活动提供至少20%的ATP,可能使高原鼠兔减小在低氧环境中对氧气的依赖,增强对低氧环境的适应能力。     

Variation in subsurface thermal characteristics of microrefuges used by range core and peripheral populations of the American pika (Ochotona princeps)

Microrefuges provide microclimates decoupled from inhospitable regional climate regimes that enable range‐peripheral populations to persist and are important to cold‐adapted species in an era of accelerated climate change. However, identifying and describing the thermal characteristics of microrefuge habitats is challenging, particularly for mobile organisms in cryptic, patchy habitats. We examined variation in subsurface thermal conditions of microrefuge habitats among different rock substrate types used by the American pika (Ochotona princeps ), a climate‐sensitive, rock‐dwelling Lagomorph. We compared subsurface temperatures in talus and lava substrates in pika survey sites in two US national park units; one park study area on the range periphery and the other in the range core. We deployed paired sensors to examine within‐site temperature variation. We hypothesized that subsurface temperatures within occupied sites and structurally complex substrates would be cooler in summer and warmer in winter than unoccupied and less complex sites. Although within‐site variability was high, with correlations between paired sensors as low as 47%, we found compelling evidence that pikas occupy microrefuge habitats where subsurface conditions provide more thermal stability than in unoccupied microhabitats. The percentage of days in which microhabitat temperatures were between ?2.5 and 25.5°C was significantly higher in occupied sites. Interestingly, thermal conditions were substantially more stable (p  < .05) in the lava substrate type identified to be preferentially used by pikas (pahoehoe vs. a'a) in a previous study. Our study and others suggest that thermal stability appears to be the defining characteristic of subsurface microrefuges used by American pikas and is a likely explanation for enigmatic population persistence at the range periphery. Our study exemplifies an integrated approach for studying complex microhabitat conditions, paired with site use surveys and contextualized with information about gene flow provided by complementary studies.     

高寒草甸生态系统中高原鼠兔的繁殖特征

2002年4月至8月,在中国科学院海北高寒草甸生态系统定位站附近,采用标志重捕法对高原鼠免的繁殖特征进行了研究。高原鼠兔的繁殖具有明显的季节性差异,4月下旬和5月为繁殖高峰期,雄性的睾丸重而饱满,雌性的怀孕率最大。雄性成体的体重和睾丸重在繁殖期的不同时段具有显的差异,在4月11日至5月10日、6月11日至7月10日体重和睾丸重之间呈显正相关。雌性怀孕早期胚胎数与临产前胚胎数没有显差异,未发现胚胎吸收现象;同时,胚胎数在繁殖期的不同时段存在显差异。采用种群统计学中同生群的划分方法,将5～8月份出生的幼体依次记为L1、L2、L3、L4。在出生后20天内L1、L2幼体存活率明显高于L3、L4;在从出生50天至80天期间L4的存活率显高于L2。当年出生的雌雄幼体在发育上存在不同步现象,当年出生的雌性幼体性成熟早,有的可以直接参加繁殖,但当年出生的雄性幼体却无此现象。结果表明：在海北地区,经过综合治理后,高原鼠兔的生境发生改变,其繁殖策略也随之发生改变,即,减少每次繁殖活动的投入,增加繁殖次数,延长繁殖时间。     

高原鼢鼠和高原鼠兔红细胞低氧适应特征

为探讨高原鼢鼠对低氧高二氧化碳洞道生境及高原鼠兔对高海拔低氧生境的适应机制,用Sysmex SF-3000血细胞分析仪及聚丙烯酰胺凝胶电泳对两种高原动物的血常规及血红蛋白类型进行分析,后者采用聚丙烯酰胺凝胶电泳法。结果表明,高原鼢鼠和高原鼠兔的红细胞数(RBC)、红细胞压积(HCT)及平均红细胞容积(MCV)组间无显著差异(P>0.05),但高原鼢鼠和高原鼠兔的红细胞数显著高于SD大鼠,红细胞压积及平均红细胞容积均显著低于SD大鼠(P<0.05);高原鼢鼠的血红蛋白浓度(HBC)与SD大鼠无显著差异(P>0.05),但显著高于高原鼠兔的HBC(P<0.05)。高原鼢鼠血红蛋白主要有2种类型,高原鼠兔血红蛋白主要有3种类型,而SD大鼠血红蛋白主要有5种类型。从血红蛋白电泳迁移来看,2种高原动物血红蛋白类型有明显的趋同特征并与SD大鼠具有明显的差异。上述结果提示,长期适应高海拔低氧环境的高原动物的红细胞和血红蛋白表现出趋同进化,同时因生境和习性的差异又表现出各自的特异性。     

高原鼠兔和根田鼠的最大代谢率

采用He-O2混合诱导方法测定了高原鼠兔（Ochotona curzoniae）和根田鼠（Microtus oeconomus）的最大代谢率（MMR）。高原鼠兔的最大代谢率在夏季和冬季分别为5．93（体重为118g）和6．33（体重为115．8g）mlO2/g.h,而根田鼠在夏季和冬季分别为12．70（体重为27．8g）和18．29（体重为17．5g）mlO2/g.h,并且根田鼠的最大代谢率的变化幅度大于高原鼠兔,存在种间差异。MMR季节变化的不显著性来源于动物环境温度在夏季较低,而在冬季为越冬亦采用行为调节等其它机制。栖于青藏高原的高原鼠兔和根田鼠同时受到低温和低氧的腔迫,而两者对最大代谢率作用相反,导致两种动物的最大代谢率与各自期望值相比差异不大。     

相关风险因子对高原鼠兔摄食行为的影响

研究了捕食风险环境中集和洞口距离对高原鼠兔摄食行为的影响。结果表明,集群数量的增加不仅降低了警觉行为,同时也减少了摄食行为,在高风险环境中,集群为1时的取食行为强度最大,低风险环境中,为0时最大,警觉行为主要出现在距洞口2m的范围内,其行为强度与洞口踪影职责负相关,当洞口距离大于3m时,风险处理区的高原鼠兔几乎无警觉行为出现,且该处理区的取食区域几乎压缩的洞口旁,研究结果表明,在捕食风险环境中,高原鼠兔摄食行为与集群和洞口距离之间具有复杂的关系,其行为决策反映了降低风险与摄取食物间的权衡,行为目标是在降低捕食风险的同时尽可能地取食食物。     

Climate‐niche factor analysis: a spatial approach to quantifying species vulnerability to climate change

Climate change vulnerability assessments are an important tool for understanding the threat that climate change poses to species and populations, but do not generally yield insight into the spatial variation in vulnerability throughout a species’ habitat. We demonstrate how to adapt the method of ecological‐niche factor analysis (ENFA) to objectively quantify aspects of species sensitivity to climate change. We then expand ENFA to quantify aspects of exposure and vulnerability to climate change as well, using future projections of global climate models. This approach provides spatially‐explicit insight into geographic patterns of vulnerability, relies only on readily‐available spatial data, is suitable for a wide range of species and habitats, and invites comparison between different species. We apply our methods to a case study of two species of montane mammals, the American pika Ochotona princeps and the yellow‐bellied marmot Marmota flaviventris.     

草地退化影响高原鼠兔血清总IgG水平、肠道寄生物感染及肝脏和肾脏指数

高原鼠兔 (Ochotona curzoniae) 作为青藏高原高寒草地生态系统中的关键物种,其种群数量随着过度放牧导致的草地退化而暴发式增长。阐明此过程中高原鼠兔天然免疫能力及肝脏和肾脏器官指数的变化,对深入揭示青藏高原草地退化引起的高原鼠兔种群暴发机理具有重要意义。本研究在青海海北高寒草地生态系统国家野外科学观测研究站地区,调查了轻度、中度、重度退化草地中高原鼠兔洞口数量,并测定了成体高原鼠兔血清总IgG含量、肠道寄生物感染状况及肝脏和肾脏指数。结果发现：随着草地退化,高原鼠兔洞口数量和血清总IgG水平显著增加;绦虫和线虫的感染率和感染强度以及肝脏和肾脏指数均显著降低。雄性对绦虫的感染率和肝脏指数显著低于雌性;雌性在重度退化草地中对绦虫和线虫的感染率及感染强度显著低于轻度退化草地。以上结果表明,过度放牧介导的草地退化增强了高原鼠兔的天然免疫功能,缓解了毒素对肝脏和肾脏的损伤,进而可能促进其种群暴发式增长。     

Of plants and pikas: evidence for a climate-mediated decline in forage and cache quality

Background: Animals that hoard food to mediate seasonal deficits in resource availability might be particularly vulnerable to climate-mediated reductions in the quality and accessibility of food during the caching season. Central-place foragers might be additionally impacted by climatic constraints on their already restricted foraging range.

Aims: We sought evidence for these patterns in a study of the American pika (Ochotona princeps), a territorial, central-place forager sensitive to climate.

Methods: Pika food caches and available forage were re-sampled using historical methods at two long-term study sites, to quantify changes over two decades. Taxa that changed in availability or use were analysed for primary and secondary metabolites.

Results: Both sites trended towards warmer summers, and snowmelt trended earlier at the lower latitude site. Graminoid cover increased at each site, and caching trends appeared to reflect available forage rather than primary metabolites. Pikas at the lower latitude site preferred species higher in secondary metabolites, known to provide higher-nutrient winter forage. However, caching of lower-nutrient graminoids increased in proportion with graminoid availability at that site.

Conclusions: If our results represent trends in climate, cache quality and available forage, we predict that pikas at the lower latitude site will soon face nutritional deficiencies.