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51.
The American amphipod species Melita nitida andIncisocalliope aestuarius have been found in the WesternScheldt estuary (the Netherlands). This is the first record of these species inthe north-east Atlantic. Shipping is the most likely vector of introduction.Thedistribution of both species is investigated and compared with the distributionand the microhabitat of co-occurring amphipod species. Melitanitida is known from both the east and west coast of North Americaand I. aestuarius originates from the east coast of NorthAmerica. Until now neither has been reported from other parts of the world. Inthe Netherlands both species are restricted to the mesohaline part of theWestern Scheldt. Melita nitida occurs predominantly underPacific oysters at the underside of boulders, mainly sublittorally.Incisocalliope aestuarius is associated to hydrozoans.Bothmicrohabitats are hardly utilized by other amphipod species. Therefore, thetheory that the existence of many empty niches in north-western Europeanbrackish waters make this environment particularly susceptible to invasions ofalien species is corroborated. The application of hard substrates in a regionoriginally predominated by soft bottoms moreover facilitates the introductionofexotic species. The species community on hard substrates in the mesohaline partof the Western Scheldt contains a high proportion of introduced species:approximately one third of the macrofauna species is of allochthonous origin.  相似文献   
52.
The objective of this study was to assess the reliability and feasibility of a novel object test assessing fear in pigs in commercial conditions. A total of 18 commercial farms were visited, and 321 pens housing 4,220 growing pigs were assessed. Three balloons were used as a novel stimulus. Measures were (a) the time it took for the first pig to contact 1 of the balloons, (b) percentage of nonhuman animals watching the balloons each for 10 s, and (c) percentage of animals touching the balloons during periods of 5 s. The time of the first pig to contact 1 of the balloons ranged from 0 s to 362 s. An effect of the farm was found (p < .0001) for contact latency, ranging from 6.8 s to 73.3 s, but little difference was found in terms of intrafarm variability. Interobserver repeatability was also high in this measure, ranging from r = .74 to r = .96. As a result, it is concluded that contact latency could be a good measure to assess fear of a novel stimulus in commercial farms.  相似文献   
53.
We investigated whether capuchin monkeys (Cebus apella) would choose to observe a high- or low-status adult female from their group during experimental foraging tests. The subject was located in the center of a test chamber, with a low- and high-ranking demonstrator on either side of two partitions. A peephole allowed the subject to observe the models by looking through either respective partition. Each model was trained on one of the two different methods, lift or pull, for retrieving food from a foraging apparatus. There were 22 subjects and four models. During the 40-trial test sessions, subjects could choose which model they would watch in each trial. It was predicted that subjects would prefer observing the model with whom it was closer in rank, and therefore share greater affiliation with. Results showed that only half the subjects showed a preference and that preference was not linked to status. Relatedness played a larger role in determining if a subject showed a preference for a model, and a correlation was found for relatedness and observer preference. After the observer preference tests, subjects were presented with the foraging apparatus to determine if they displayed a preference for one of the two tasks. The majority of subjects (17/22) showed a preference for the pull method, suggesting that this method may have been more salient to the monkeys in this study.  相似文献   
54.
Domestic dogs are particularly skilled at using human visual signals to locate hidden food. This is, to our knowledge, the first series of studies that investigates the ability of dogs to use only auditory communicative acts to locate hidden food. In a first study, from behind a barrier, a human expressed excitement towards a baited box on either the right or left side, while sitting closer to the unbaited box. Dogs were successful in following the human''s voice direction and locating the food. In the two following control studies, we excluded the possibility that dogs could locate the box containing food just by relying on smell, and we showed that they would interpret a human''s voice direction in a referential manner only when they could locate a possible referent (i.e. one of the boxes) in the environment. Finally, in a fourth study, we tested 8–14-week-old puppies in the main experimental test and found that those with a reasonable amount of human experience performed overall even better than the adult dogs. These results suggest that domestic dogs’ skills in comprehending human communication are not based on visual cues alone, but are instead multi-modal and highly flexible. Moreover, the similarity between young and adult dogs’ performances has important implications for the domestication hypothesis.  相似文献   
55.
Autophagy plays a key role in the pathophysiology of schizophrenia as manifested by a 40% decrease in BECN1/Beclin 1 mRNA in postmortem hippocampal tissues relative to controls. This decrease was coupled with the deregulation of the essential ADNP (activity-dependent neuroprotector homeobox), a binding partner of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 β) another major constituent of autophagy. The drug candidate NAP (davunetide), a peptide fragment from ADNP, enhanced the ADNP-LC3B interaction. Parallel genetic studies have linked allelic variation in the gene encoding MAP6/STOP (microtubule-associated protein 6) to schizophrenia, along with altered MAP6/STOP protein expression in the schizophrenic brain and schizophrenic-like behaviors in Map6-deficient mice. In this study, for the first time, we reveal significant decreases in hippocampal Becn1 mRNA and reversal by NAP but not by the antipsychotic clozapine (CLZ) in Map6-deficient (Map6+/−) mice. Normalization of Becn1 expression by NAP was coupled with behavioral protection against hyperlocomotion and cognitive deficits measured in the object recognition test. CLZ reduced hyperlocomotion below control levels and did not significantly affect object recognition. The combination of CLZ and NAP resulted in normalized outcome behaviors. Phase II clinical studies have shown NAP-dependent augmentation of functional activities of daily living coupled with brain protection. The current studies provide a new mechanistic pathway and a novel avenue for drug development.  相似文献   
56.
We recorded the responses of the members of a captive group of wedge-capped capuchins to novel and familiar objects placed in different parts of their cage in a study of the spatial dependency of activity with objects. We focused on behavioral pattern variability across subjects and across object location. Results show that, according to the location of the object, a great deal of within-subject response variability exists. The dominant male was slow to interact physically with objects and presented social-like behaviors—essentially grooming—towards objects in only one site. Implicit to the ethological approach is the assumption that consistent spatial location is irrelevant or, at best, of little importance to the definition of stimuli. Nevertheless, stimuli would be best considered as perturbations insofar as the significance of an object or event depends on where and when it is encountered. In order to evaluate how monkey cognition operates, it seems essential to investigate the role of the primate's own spatial structure. As a working hypothesis, we introduce the processes of spatial facilitation and inhibition and suggest that they affect how an individual interacts with objects and events.  相似文献   
57.
Philosophers and historians of biology have argued that genes are conceptualized differently in different fields of biology and that these differences influence both the conduct of research and the interpretation of research by audiences outside the field in which the research was conducted. In this paper we report the results of a questionnaire study of how genes are conceptualized by biological scientists at the University of Sydney, Australia. The results provide tentative support for some hypotheses about conceptual differences between different fields of biological research.  相似文献   
58.
A global data set on forest cover change was recently published and made freely available for use (Hansen et al. 2013. Science 342: 850–853). Although this data set has been criticized for inaccuracies in distinguishing vegetation types at the local scale, it remains a valuable source of forest cover information for areas where local data is severely lacking. Masoala National Park, in northeastern Madagascar, is an example of a region for which very little spatially explicit forest cover information is available. Yet, this extremely diverse tropical humid forest is undergoing a dramatic rate of forest degradation and deforestation through illegal selective logging of rosewood and ebony, slash‐and‐burn agriculture, and damage due to cyclones. All of these processes result in relatively diffuse and small‐scale changes in forest cover. In this paper, we examine to what extent Hansen et al.'s global forest change data set captures forest loss within Masoala National Park by comparing its performance to a locally calibrated, object‐oriented classification approach. We verify both types of classification with substantial ground truthing. We find that both the global and local classifications perform reasonably well in detecting small‐scale slash‐and‐burn agriculture, but neither performs adequately in detecting selective logging. We conclude that since the use of the global forest change data set requires very little technical and financial investment, and performs almost as well as the more resource‐demanding, locally calibrated classification, it may be advantageous to use the global forest change data set even for local conservation purposes.  相似文献   
59.
“大范围优先”对象形成的神经关联:前颞叶   总被引:1,自引:0,他引:1  
陈霖 《生命科学》2008,20(5):718-721
知觉对象是什么?这事看起来很简单,却是认知科学许多领域中最核心的问题,日前为止还没有公认的解答。“大范围优先”的拓扑学方法把知觉对象的定义严格地联系到拓扑变换下的不变量。知觉对象的直观概念—形状改变时其整体一致性得以保持一可以精确地被拓扑不变量,如连接组分和洞,所刻画。知觉对象的拓扑学定义已经被大量的行为学实验所验证。这些实验一致表明,虽然对象的一致性能够在非拓扑变换下得以保持,却会被拓扑变换所破坏,从而一个新的对象被感知到。特别是进一步的功能磁共振成像实验揭示,前颞页区参与拓扑知觉和知觉对象的形成,而这一脑区本来是形式视觉通路的终点。行为学上“大范围优先”的结果与视觉通路神经解剖学结果的悖逆,提示我们应该注意对象表征形成的问题和更广泛的意义上,知觉到底在何处发生的基本问题。  相似文献   
60.
获取鸟类活动及生境信息是鸟类生态学研究的基础, 而遥感技术弥补了传统野外调查方法的缺陷, 提供了获取多种信息的新途径。应用遥感技术的鸟类生态学研究热点从最初的种群行为观察, 到栖息地选择, 再到生境适宜性、破碎化及人为干扰探究等, 随着技术的不断发展也在扩展和变化。不同波段或组合下的遥感技术各有所长。光学遥感应用广泛, 尤其是信息量较大的红外波段图像和作为野外鸟巢及物种活动监测常用工具的红外相机; 多光谱图像常用于栖息地制图以及地物识别, 高空间分辨率的数据甚至可对鸟类种群进行直接计数; 高光谱数据则可对光谱特征相似的地物进行更为精确的区分和反演; 激光雷达遥感主要用于栖息地植被结构的三维探测, 为了解鸟类栖息地选择提供更好的依据。微波遥感在飞鸟探测上应用颇多, 近年来多极化数据在复杂栖息地精确制图上也具有优势, 但成本较高、解译复杂且推广度较低。在实际应用中, 遥感数据时空尺度的选择会影响研究结果, 部分遥感反演参数也缺乏生态学意义。多源遥感数据的结合应用能够提升制图分类的精度, 实现数据的时空分辨率互补, 优化鸟类生态研究所需参数。未来的遥感技术在鸟类生态学中的应用应致力于提供更加明确的光谱信息、相对简便的解译方法, 以及更为合理的多源数据组合方式等。  相似文献   
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