关键词： caching   deceptive behaviour   eastern grey squirrel   hoarding   pilfering   scatter hoarding   Sciurus carolinensis  

摘要： Behavioural deception has been studied experimentally primarily in captive-raised primates and corvids, and only in a laboratory setting. Here we show that free-living eastern grey squirrels, Sciurus carolinensis, caching food in the presence of conspecifics perform behavioural deception by covering additional empty sites where nothing has been cached. Such deceptive caching (1) occurred in two distinct populations, (2) occurred more often in the close presence of conspecifics and (3) reduced the probability of cache pilferage by surrogate (human) cache pilferers. In an additional experiment, in which we attempted to elicit deceptive behaviour by pilfering caches, deceptive caching appeared as one behaviour in a suite of pilferage-avoidance responses. To our knowledge, this is the first study to show evidence of behavioural deception by a rodent, and the first to use an experimental approach to studying deceptive behaviour in the wild. (C) 2007 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

关键词： MUTUALISM   ANTS   BIODIVERSITY   BIOTIC communities   ECOLOGY   SAVANNAS   SYMBIOSIS   INSECT societies   HERBIVORES  

摘要： Mutualisms are key components of biodiversity and ecosystem function, yet the forces maintaining them are poorly understood. We investigated the effects of removing large mammals on an ant-Acacia mutualism in an African savanna. Ten years of large-herbivore exclusion reduced the nectar and housing provided by plants to ants, increasing antagonistic behavior by a mutualistic ant associate and shifting competitive dominance within the plant-ant community from this nectar-dependent mutualist to an antagonistic species that does not depend on plant rewards. Trees occupied by this antagonist suffered increased attack by stem-boring beetles, grew more slowly, and experienced doubled mortality relative to trees occupied by the mutualistic ant. These results show that large mammals maintain cooperation within a widespread symbiosis and suggest complex cascading effects of megafaunal extinction.

关键词： Piper methysticum   kava   kava pyrones   kavalactones   mutagenicity   mouse lymphoma  

摘要： Kava (Piper methysticum) is a member of the pepper family and has been cultivated by South Pacific islanders for centuries and used as a social and ceremonial drink. Traditionally, kava extracts are prepared by grinding or chewing the rhizome and mixing with water and coconut milk. The active constituents of kava are a group of approximately 18 compounds collectively referred to as kavalactones or kava pyrones. Kawain, dihydrokawain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin are the six major kavalactones. Kava beverages and other preparations are known to be anxiolytic and are used for anxiety disorders. Dietary supplements containing the root of the kava shrub have been implicated in several cases of liver toxicity in humans, including several who required liver transplants after using kava supplements. In order to study the toxicity and mutagenicity, two commercial samples of kava, Kaviar and KavaPure, and the six pure kavalactones including both D-kawain and DL-kawain, were evaluated in L5178Y mouse lymphoma cells. Neither the kava samples nor the kavalactones induced a mutagenic response in the L5178Y mouse lymphoma mutation assay with the addition of human liver S9 activation. (c) 2007 Elsevier Ltd. All rights reserved.

关键词： 动物园   事业   实践活动   解放思想  

摘要： 根据石园党字[2008]10号文《关于围绕三年大变样开展双创双树主题实践活动的实施意见》,结合我园边建设,边开放的实际,紧紧围绕突出创新,突出实践,突出标准,突出解决实际问题这四

关键词： 动物   肝炎病毒   模型   树胸  

摘要： 肝炎的的大范围流行已成为国内外关注的重要公共卫生问题之一。甲肝、乙肝虽已有疫苗,但不能忽视未来由于病毒变异所带来的威胁。丙肝目前尚未发现非常有效的疫苗,且丙肝的病理学机制也尚未完全清晰,主要原因是缺乏理想的动物模型。树胸属于低等灵长类动物。研究发现,他对很多人类疾病易感,所以建立肝炎树胸动物模型成为现在肝炎研究的一个热点。本文介绍了各型肝炎主要是甲、乙、丙型肝炎研究中建立树胸动物模型的自内外进展情况及存在的问题。

关键词： 株树桥水库   浮游动物   群落生态   水质评价   环境保护  

摘要： 对株树桥水库进行为期一周年的浮游动物群落结构特征研究,以期利用浮游动物群落结构变化,并结合理化指标对株树桥水库进行水质综合评价,进而为水库的合理、有效地利用提供基础资料。2007年5月至2001年4月,在水库的主要干道设置10个采样点,对浮游动物进行定性和定量的采集,同步进行温度、PH值和电导率三项物理指标以及氨氮、总磷、总氮、COD和溶解氧五项化学指标的测定。　　 通过浮游动物的种类鉴定,确定了常见种和优势种,同时分析研究了浮游动物群落变化以及温度、pH值、溶解氧和氨氮对浮游动物群落的影响。主要结果如下:　　 株树桥水库共鉴定出浮游动物184种。其中原生动物95种,轮虫71种,枝角类10种,桡足类8种。夏季和秋季的种类数较多,分别达120和138种;春季和冬季次之,种类数分别为72种和64种;而全年均出现的种类有36种。　　 株树桥水库10个采样点的浮游动物数量和生物量的年际变化趋势基本一致,全年浮游动物数量的变动幅度为712-4190ind./L,生物量变动幅度为0.347-2.783mg/L。　　 在水平分布上,上游入口的年均数量最多,生物量最多在升平口,数量和生物量大坝1均最少;在季节分布上,株树桥水库浮游动物数量和生物量在不同季节波动较大,数量表现为秋季>夏季>春季>冬季。生物量表现为夏季>秋季>春季>冬季。　　 浮游动物多样性指数、丰富度指数、均匀度指数大致都是9月,11月较高,1月份最低,优势集中性指数则相反。　　 浮游动物种类数有随着温度的升高而增加的趋势;种类数的年际变化与水体PH的变化关系不明显;浮游动物数量在夏、秋季节与溶解氧含量有显著的相关性;氨氮量高的冬春季,浮游动物种类较少,氨氮量低的夏秋季,浮游动物种类反而较高。　　 通过理化指标的测定,采用化学评价指数(Pb/n)和评分法对内河水质进行评价。同时利用浮游生物现存量、指示生物法、三种多样性指数即Simpson多样性指数、Shannon-Wearer多样性指数和Margalef多样性指数,分别对水库进行水质生物学评价。最后,结合理化指标,对水库进行了营养型评价。　　 综合各种评价方法,测定水库的水质大多处于寡污至乙型中污之间,营养型主要为中营养型。最后结合目前水库水质状况,提出合理开发利用的意见和建议。

关键词： 株树桥水库   浮游动物   群落生态   水质评价   环境保护  

摘要： 对株树桥水库进行为期一周年的浮游动物群落结构特征研究,以期利用浮游动物群落结构变化,并结合理化指标对株树桥水库进行水质综合评价,进而为水库的合理、有效地利用提供基础资料。2007年5月至2001年4月,在水库的主要干道设置10个采样点,对浮游动物进行定性和定量的采集,同步进行温度、PH值和电导率三项物理指标以及氨氮、总磷、总氮、COD和溶解氧五项化学指标的测定。 通过浮游动物的种类鉴定,确定了常见种和优势种,同时分析研究了浮游动物群落变化以及温度、pH值、溶解氧和氨氮对浮游动物群落的影响。主要结果如下： 株树桥水库共鉴定出浮游动物184种。其中原生动物95种,轮虫71种,枝角类10种,桡足类8种。夏季和秋季的种类数较多,分别达120和138种;春季和冬季次之,种类数分别为72种和64种;而全年均出现的种类有36种。 株树桥水库10个采样点的浮游动物数量和生物量的年际变化趋势基本一致,全年浮游动物数量的变动幅度为712-4190ind./L,生物量变动幅度为0.347-2.783mg/L。 在水平分布上,上游入口的年均数量最多,生物量最多在升平口,数量和生物量大坝1均最少;在季节分布上‘,株树桥水库浮游动物数量和生物量在不同季节波动较大,数量表现为秋季>夏季>春季>冬季。生物量表现为夏季>秋季>春季>冬季。 浮游动物多样性指数、,丰富度指数、均匀度指数大致都是9月,11月较高,1月份最低,优势集中性指数则相反。 浮游动物种类数有随着温度的升高而增加的趋势;种类数的年际变化与水体PH的变化关系不明显;浮游动物数量在夏、秋季节与溶解氧含量有显著的相关性;氨氮量高的冬春季,浮游动物种类较少,氨氮量低的夏秋季,浮游动物种类反而较高。 通过理化指标的测定,采用化学评价指数(Pb/n)和评分法对内河水质进行评价。同时利用浮游生物现存量、指示生物法、三种多样性指数即Simpson多样性指数、Shannon-Wearer多样性指数和Margalef多样性指数,分别对水库进行水质生物学评价。最后,结合理化指标,对水库进行了营养型评价。 综合各种评价方法,测定水库的水质大多处于寡污至乙型中污之间,营养型主要为中营养型。最后结合目前水库水质状况,提出合理开发利用的意见和建议。

关键词： Saplings   Herbivores   Regrowth   Browsing   Savannas   Applied ecology   Ungulates   Animal social behavior   Forest ecology  

摘要： Suppressed growth forms of woody species are common where fire and herbivory are major ecosystem drivers, such as in African savannas. Nevertheless, despite their importance in maintaining plant population viability, woody plants in suppressed growth forms have received little attention in ecological studies. We measured a set of morpho-functional traits and investigated plant density variation in suppressed growth forms (hereafter we refer to them as saplings) of two common species, Acacia nigrescens and Acacia tortilis, across sites that had undergone very different histories of attack from large herbivores while fire had been absent for at least 13 y. We show that heavily browsed saplings have higher regrowth abilities, twice the number of stems produced by the main root crown and twice the root diameter at 5 cm soil depth, than lightly browsed saplings. This suggests that Acacia saplings are resilient to chronic herbivory and show high morphological plasticity. However, we show that mammalian herbivores can strongly limit sapling recruitment to mature size classes and possibly affect variation in sapling density between heavily and lightly browsed sites. Further studies should investigate whether the persistence of the sapling bank can be ascribed to the "storage effect" by which a plant's reproductive potential is "stored" in a suppressed growth form until a window of opportunity allows rapid maturity. Des formes réduites de croissance d'espèces ligneuses sont communes lorsque le feu et les herbivores sont des forces majeures de l'écosystème comme dans les savanes africaines. Néanmoins les formes réduites de croissance d'espèces ligneuses ont reçues peu d'attention dans les études écologiques et ce malgré leur importance dans le maintien de la viabilité des populations. Nous avons mesuré une série de traits morpho-fonctionnels et examiné les variations de la densité de plants de formes réduites de croissance (référés ci-dessous en tant que gaules) de deux espèc

关键词： yellow mongoose   rangeland   individual-based model   shrub encroachment   spatial explicit   structural diversity  

摘要： In arid and semi-arid savannas, species diversity is strongly influenced by structural diversity, which in these systems is characteristically formed by woody vegetation. Shrub encroachment, associated with overgrazing by domestic livestock, changes the structural diversity and hence affects biodiversity. Many investigations have been carried out with focus on the structure building trees, but little is known about the importance of shrubs. Here, we present a spatially explicit and individual-based population model for analysing the influence of shrub encroachment on the occurrence of yellow mongooses (Cynictis penicillata) in the Southern Kalahari, South Africa. This analysis is based on field investigations in Southern Africa. The results of the modelling study are in line with the results of a field study, in which the same unimodal relationship between shrub cover and yellow mongoose abundance was found. The model could explain this relationship by the need of shrubs as protective structures on the one hand, and the need of foraging habitat in the grass matrix on the other hand. To evaluate the factors influencing the population dynamics at different levels of shrub encroachment we carried out an extensive sensitivity analysis. Finally, we determined a range of existence of the yellow mongoose for various shrub covers. Model results indicate a lower and an upper limit of critical shrub densities at 1% and 38%, respectively. These limits indicate the range in shrub cover allowing the persistence of the yellow mongoose in the Southern Kalahari. (C) 2007 Elsevier B.V. All rights reserved.

关键词： 哺乳动物   进化树   进化论   南美洲   博物学   袋鼠   袋狼  

摘要： 在方舟子先生的《进化论简史》一书中，有这样一段表述：当博物学家在澳洲和南美洲见到袋鼠、袋狼、袋熊、袋鼬、袋貂、袋獾等等闻所未闻的动物，就不免奇怪为什么上帝只在这里创造出有袋类哺乳动物。这并非那里的环境是为有袋类而设的，因为当移民们给这些地方带去高等哺乳动物后，