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991.
Do infants preferentially learn to fear stimuli that represent an ancestral danger? This question was addressed using event-related brain potentials in 9-month-old infants (N = 38). In Experiment 1, infants saw fearful and neutral faces gazing towards spiders and flowers. Then spiders and flowers were presented again without faces. Infants responded with increased attention (signaled by the Negative central, Nc component) to stimuli associated with fear. In particular, spiders that were gaze-cued with a fearful as compared to a neutral expression elicited an increased Nc response. In Experiment 2, targets were snakes and fish. Snakes elicited increased Nc amplitude compared to fish irrespective of emotion condition. Results speak to the evolution-based fear-relevance of spiders and snakes. Our findings provide partial support for social fear learning and preparedness theory (Experiment 1) and non-associative accounts of fear acquisition (Experiment 2). We conclude that both kinds of fear acquisition seem to play a role in early human development.  相似文献   
992.
A number of empirical studies have suggested that individual differences in asocial exploration tendencies in animals may be related to those in social information use. However, because the ‘exploration tendency’ in most previous studies has been measured without considering the information-gathering processes, it is yet hard to conclude that the animal asocial exploration strategies may be tied to social information use. Here, we studied human learning behaviour in both asocial and social two-armed bandit tasks. By fitting reinforcement learning models including asocial and/or social decision processes, we measured each individual's (1) asocial exploration tendency and (2) social information use. We found consistent individual differences in the exploration tendency in the asocial tasks. We also found substantive heterogeneity in the adopted learning strategies in the social task: Nearly one-third of participants used predominantly the copy-when-uncertain strategy, while the remaining two-thirds were most likely to have relied only on asocial learning. However, we found no significant individual association between the exploration frequency in the asocial task and the use of the social information in the social task. Our results suggest that the social learning strategies may be independent from the asocial exploration strategies in humans.  相似文献   
993.
不育控制既可直接降低害鼠种群的生育率,又能影响个体的社会行为,引起种群内等级关系和社群结构的变化,进而干扰种群繁殖。为探究不同剂量卡麦角林对雄鼠行为的影响和持效时间,选取健康雄性黄毛鼠使用50mg/kg和100 mg/kg卡麦角林灌胃给药,并于给药后第1 d和第18 d与正常雄鼠遭遇,第4 d和第21 d与正常雌鼠遭遇,比较给药前(卡麦角林灌胃前4 d和前1 d 时分别与正常雄鼠和雌鼠遭遇)和给药后个体行为的差异。结果显示:卡麦角林降低了雄鼠对正常雄鼠的探究、攻击时间,降低雄鼠对正常雌鼠的攻击时间和频次;100 μg/kg卡麦角林降低雄鼠对正常雌鼠的探究频次,且雄鼠自身修饰和休息频次显著减少。这表明卡麦角林可干扰黄毛鼠对同性和异性个体间的社会行为。此外,药物处理后第18 d和第21 d,雄性个体与同性和异性个体的社会行为与处理前无显著差异,表明停药后药物对行为的影响会随着时间的延长逐渐消失。    相似文献   
994.
先前的研究表明,性别、年龄、蜱虫密度、季节等因素会影响大丰自然保护区中重引入麋鹿的口部搔痒行为,因此野生动物重引入需要考虑该种群是否仍保留瘙痒行为以便有效抵御皮外寄生虫尤其是蜱虫的侵扰。在本次研究中,我们进一步探讨了两个可能会影响麋鹿搔痒行为的因素:社会等级和食物供给。在发情季节,麋鹿群主通常具有较高水平的睾酮水平,进而抑制搔痒行为,所以我们预测群主的搔痒频率应该会低于单身汉。但是群主和单身汉的搔痒频率并没有差别,这可能是因为观察期处于发情末期,睾酮水平已经下降。食物供给也可能会影响搔痒行为,因为其可以减轻采食压力,从而释放了其他行为如搔痒的时间。然而我们也没有发现食物供给的影响,这可能是因为围栏小种群的游客较多,使得警戒行为占据了采食压力释放后的行为时间。我们建议未来改变行为观察时间,并排除游客干扰,从而进一步探讨这两个因素对麋鹿搔痒行为的影响。  相似文献   
995.
灵长类动物社会中,个体间的社会关系是维系群体稳定的重要基础,也影响个体的寿命和繁殖成功。本研究以栖息于安徽黄山的短尾猴YA1群为对象,采用焦点动物取样法和行为取样法采集成年雌性个体在交配期(2015.9 - 2015.12)和非交配期(2016.3 - 2016.5)的社会行为,通过理毛和近距行为计算社会联系强度,探讨群体成员之间的社会关系及影响因素。结果表明:在交配期和非交配期,雌性短尾猴的社会联系强度无显著差异(t = 0.181,P = 0.857);亲缘关系和社会联系强度呈显著正相关(交配期:r = 0.534, P = 0.001; 非交配期:r = 0.469, P= 0.001);个体间的等级距离和社会联系强度呈显著负相关(交配期:r = -0.288, P= 0.014; 非交配期:r = -0.238, P= 0.048);年龄差异和社会联系强度无显著相关性(交配期:r = -0.176, P = 0.181; 非交配期:r = -0.192, P = 0.151)。本研究提示成年雌性短尾猴个体间会形成稳定的社会关系,亲缘关系和等级顺位是影响个体之间社会关系的重要因素。  相似文献   
996.
The purpose of this study is to assess the resilience of socio-ecological production landscapes and seascapes (SEPLS) of Lefke Region in North Cyprus in the face of disturbance factors (e.g. drought, urbanization and land abandonment) by adopting a set of indicators. The main objectives of the study include measurement of the respective resilience of the ecological, social and agricultural systems of the SEPLS by using relevant indicators. The method of the study consists of three parts: (i) conceptualization of the resilience of the SEPLS of Lefke Region to address the key systems (ecosystem, agricultural and social), their hierarchical structures, components and interrelations; (ii) development of a set of suitable resilience assessment indicators for these systems; (iii) for the development of resilience assessment indicators a participatory approach was designated to collect the relevant data. Accordingly, a multiple-choice questionnaire – consisting of 5 choices – was prepared and relevant data were collected from December 2015 to March 2016 in 12 villages through personal interviews with 106 respondents.The respondents have expressed their preferences by selecting the most suitable choice in 5 which were ordered from the lowest to the highest degree of resilience (1–5 point scale). The results of the evaluation revealed that the average values (importance) of the ecological, agricultural and social resilience are respectively 2,87 (low), 3,44 (moderate) and 2,53 (low) out of maximum 5-points. The overall resilience of the SEPLS was estimated to be low with a 2,94 magnitude. Finally, some conclusions (e.g. integrated landscape management) for strengthening the resilience of the SEPLS in Lefke Region in terms of biodiversity conservation, agricultural production and sustainable livelihood development were drawn based on the major findings of the study.It is expected that the findings and conclusions of this study can draw attention of policy makers and natural resource managers on building and strengthening the resilience of the SEPLS of Lefke Region in terms of biodiversity conservation, sustainable agricultural production and livelihood development.  相似文献   
997.
Problem-solving competence at group level is influenced by the structure of the social networks and so it may shed light on the organization patterns of gregarious animals. Here we use an agent-based model to investigate whether the ubiquity of hierarchical networks in nature could be explained as the result of a selection pressure favoring problem-solving efficiency. The task of the agents is to find the global maxima of NK fitness landscapes and the agents cooperate by broadcasting messages informing on their fitness to the group. This information is then used to imitate, with a certain probability, the fittest agent in their influence networks. The performance of the group is measured by the time required to find the global maximum. For rugged landscapes, we find that the modular organization of the hierarchical network with its high degree of clustering eases the escape from the local maxima, resulting in a superior performance as compared with the scale-free and the random networks. The optimal performance in a rugged landscape is achieved by letting the main hub to be only slightly more propense to imitate the other agents than vice versa. The performance is greatly harmed when the main hub carries out the search independently of the rest of the group as well as when it compulsively imitates the other agents.  相似文献   
998.
用RT-PCR方法从青蒿(Artemisia annua L.)中克隆了一个1 539 bp全长鲨烯合酶cDNA.青蒿鲨烯合酶氨基酸序列与拟南芥、烟草、人类、酵母鲨烯合酶的一致性分别为70%、77%、44%和39%.青蒿鲨烯合酶基因组DNA结构很复杂,包括14个外显子和13个内含子.全长的或C末端截短的鲨烯合酶cDNA被克隆进原核表达载体pET30a并在大肠杆菌(Escherichia coli) BL21(DE3)中诱导表达.但在含有全长的鲨烯合酶cDNA的大肠杆菌中并没有观察到预期大小的鲨烯合酶表达,而C末端截短疏水区30个氨基酸的鲨烯合酶可在大肠杆菌中过量表达.  相似文献   
999.
One of the most critical features of human society is the pervasiveness of cooperation in social and economic exchanges. Moreover, social scientists have found overwhelming evidence that such cooperative behavior is likely to be directed toward in-group members. We propose that the group-based nature of cooperation includes punishment behavior. Punishment behavior is used to maintain cooperation within systems of social exchange and, thus, is directed towards members of an exchange system. Because social exchanges often take place within groups, we predict that punishment behavior is used to maintain cooperation in the punisher's group. Specifically, punishment behavior is directed toward in-group members who are found to be noncooperators. To examine this, we conducted a gift-giving game experiment with third-party punishment. The results of the experiment (N=90) support the following hypothesis: Participants who are cooperative in a gift-giving game punish noncooperative in-group members more severely than they punish noncooperative out-group members.  相似文献   
1000.
We characterize the spatial organization of red-tailed sportive lemurs (Lepilemur ruficaudatus) as a key aspect of their social organization and social system. Sportive lemurs are small (<1000 g), nocturnal and folivorous primates endemic to Madagascar. We studied a population of 57 individually-marked individuals in Kirindy Forest, western Madagascar, between 1995 and 2001. We radio-tracked 20 males and 26 females of the marked population to obtain detailed information on the size and location of their home ranges. Census data and morphometric measurements provided complementary data sets. Males and females occupied small (<1 ha) home-ranges. Long-term records from 9 individuals revealed home-range stability over several years. In 4 cases home ranges overlapped extensively with that of one member of the opposite sex; in 2 cases, a spatial association of 1 male and 2 females occurred. However, home ranges overlapped very little with neighboring individuals of both sexes. During the study period, spatially associated individuals used on average 5.6 sleeping trees within 117 days, but they spent on average only about every fourth night together. The data suggest that home ranges in red-tailed sportive lemurs are exclusively used by pairs or trios and that the modal social organization of red-tailed sportive lemurs is pair-living.  相似文献   
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