Social network analysis and valid Markov chain Monte Carlo tests of null models

Analyses of animal social networks derived from group-based associations often rely on randomisation methods developed in ecology (Manly, Ecology 76:1109–1115, 1995) and made available to the animal behaviour community through implementation of a pair-wise swapping algorithm by Bejder et al. (Anim Behav 56:719–725, 1998). We report a correctable flaw in this method and point the reader to a wider literature on the subject of null models in the ecology literature. We illustrate the importance of correcting the method using a toy network and use it to make a preliminary analysis of a network of associations among eagle rays.

Gunnison’s prairie dog (<Emphasis Type="Italic">Cynomys gunnisoni</Emphasis>): testing the resource dispersion hypothesis

Few studies have experimentally tested the resource dispersion hypothesis (RDH). In this study, I tested whether space use and social organization of Gunnison’s prairie dog responded to changes in the dispersion and abundance of resources. Food manipulations were carried out during the reproductive and nonreproductive seasons across 2 years. Gunnison’s prairie dog adults responded to the experiments by decreasing territory size as food became patchier in space and time. Both males and females modified their home ranges, with no detectable difference between sexes, either prior to or during the experiments. As food became patchier in space and time, the spatial overlap of adults increased, whereas it decreased as food became more evenly dispersed. The average size of a group, defined as those individuals occupying the same territory, did not change significantly as a result of the experiments. Where changes in the composition and size of groups did occur, there was no indication that such changes were sex specific. Results from this study support critical components of the RDH and strongly suggest that patterns of space use and social structure in Gunnison’s prairie dogs are the result of individual responses to resource abundance and distribution.     

国家公园效果评价体系研究

建立国家公园是保护生物多样性和促进地方发展的重要途径之一,开展国家公园效果评价是了解国家公园功能发挥的有效途径。通过查阅大量文献及德尔菲法（Delphi）,确定了与国家公园效果相关的28个评价指标,同时以功能为主导,将评价指标归纳为5个功能指标群：保护功能指标群（7个评价指标）、科研功能指标群（6个评价指标）、游憩功能指标群（7个评价指标）、教育功能指标群（4个评价指标）和经济发展功能指标群（4个评价指标）,通过对评价指标的赋分（5分制原则）和计算权重,从而达到国家公园效果评价的量化,实现对国家公园建设效果的评价。     

Group size, queuing and helping decisions in facultatively eusocial hover wasps

In facultatively eusocial hover wasps, some females leave their natal nests while others choose to stay and become helpers. We tested whether the decisions of 126 newly emerged females to stay or leave depended on group size: the number of females already resident on their natal nests. We predicted that females would be less likely to stay in larger groups, where the benefits of helping are probably smaller and there is a smaller chance of inheriting the dominant position. We also predicted that unrelated females would be less likely to join larger groups. We manipulated group size by removing residents from nests. Newly emerged females disappeared from their natal nests at a rate of 2.5% per day, but did not disappear from manipulated nests at higher rates than controls. Experimentally reducing group size also did not increase the frequency of joiners. Newly emerged females disappeared at twice the rate of older subordinate females, suggesting the existence of a `leaving window' early in life. One problem is the difficulty of distinguishing between leaving and death. Received: 7 July 1998 / Accepted after revision: 25 October 1998     

河流水环境有机污染物的自组织预测模型及应用

自组织预测模型是前苏联学者伊万年科提出的一种非线性建模预测方法,它能有效地解决复杂非线性系统的数据处理和建模问题。该文应用它进行水环境有机污染物预测,以实际监测数据为基础,建立了一个河流有机物浓度预测的自组织模型,其检验样本的预测误差在５％以内      

珠江三角洲火电群SO2污染及防治对策研究

在已有的大气环境质量资料和污染源排放资料基础上，用建立的珠江三角洲空气污染数值模式，经验证，计算了珠江三角洲２０００年，２０１０年的电力工业的ＳＯ２污染和对３个污染防治对策方案进行了分析，认为只有采取适当的限制燃料含硫量和大型燃煤电厂烟气脱硫等防治措施，才能控制ＳＯ２污染加重的趋势。     

Indicators of visual scale as predictors of landscape preference; a comparison between groups

Landscape change alters the visual scale of agricultural landscapes, as production units get larger and strips of taller vegetation are removed between smaller units. Visual scale, defined as the perceptual units reflecting the experience of landscape rooms, visibility and openness, is considered a key factor shaping landscape preference. The visual expression of landscapes affects people in many ways; aesthetic appreciation, health and well being. In order to understand how landscape changes alter the visual scale of landscapes, and hence its effect on human beings, it is important to establish efficient and practical ways of measuring visual scale and its relation to landscape preferences. This paper presents an empirical test of the ability to predict landscape preference of two photo-based indicators of visual scale; percentage open land in the view and size of landscape rooms. A preference survey was conducted with two groups of respondents; a student group from the Norwegian University of Life Sciences (UMB) and a public group. The student group was chosen to represent future landscape professionals. Photos of landscapes varying in the expression of visual scale were shown to survey respondents, who were asked to give scores according to how much they liked the landscapes. Both indicators were found to be predictors of preference for the student group, but not for the public group. The results demonstrate that student preferences do not reflect the landscape preferences of the wider public. The different appreciation of visual scale in the landscape of future landscape professionals and the public implies that experts wanting to reflect preferences of the wider public should be cautious when evaluating the visual impact of landscape change.     

Conspecific threat,predation avoidance,and resource defense: implications for grouping in langurs

Data on langur (Presbytis entellus) populations were gathered from the literature to test the importance of three selective pressures in determining group size and composition: predation pressure, intergroup resource defense, and conspecific threat. There were no detectable difference in the size of groups in populations facing nearly intact predator communities compared to those populations where predators were severely reduced in number or absent, although there was a trend for the number of adult males per group to increase in areas with nearly intact predator communities. Using population density as an indirect measure of the frequency of intrusions into a group’s home range and thereby as an index of the demographic pressure favoring resource defense, we predicted that higher densities would result in larger defensive coalitions and higher numbers of females per group. This prediction was not upheld. Our third selective pressure, conspecific threat, encompasses those selective forces resulting from physical attack on females, infants, and juveniles. Our index of conspecific threat uses the number of non-group males divided by the number of bisexual groups, because in langurs, the major source of conspecific threat derives from non-group males who, following group take-over, kill infants, wound females, and expel juveniles from groups. This index of conspecific threat was strongly related to the mean number of resident females, was weakly related to the mean group size, but was not related to the number of males in the group. In addition, as predicted, populations with a high index of conspecific threat had higher levels of juvenile expulsion. These analyses were corroborated by a simulation model which used a computer-generated series of null populations to calculate expected slopes of immatures regressed on adult females. These randomly generated populations, matched to means and ranges of real populations, allowed us to determine if deviations of the observed slopes from the expected null slopes could be explained by variation in predation pressure, population density, or conspecific threat. We found no evidence that predation pressure was associated with decreases in immature survival in smaller groups, as would be predicted by the predation-avoidance hypothesis. We found no evidence that immature survival was compromised by small group size in high-density populations, as would be predicted by the resource-defense hypothesis. However, as the index of conspecific threat increased, groups with larger numbers of females were more successful than groups with fewer females in reducing mortality or expulsion of immatures. Overall, conspecific threat received the strongest support as a selective pressure influencing langur group size and composition, suggesting that this selective pressure should be evaluated more widely as a factor influencing composition of animal groups. Received: 23 January 1995/Accepted after revision: 18 February 1996     

朝鲜晚奥陶世——志留纪和泥盆纪地层发现的启示

本文在比较系统介绍朝鲜于60-70年代发现泥盆纪临律群和晚奥陶世—志留纪地层的基础上,论证前者西延登上山东半岛,后者指向辽东、冀东的可能性。     

南秦岭东江口岩体群Pb、Sr和Nd同位素地球化学特征及其对物源的制约

以区域地球化学研究成果为基础，通过Pb、Sr、Nd同位素特征分析，揭示出东江口岩体群的Pb同位素特征与南秦岭东段基底具有耦合关系，而与其它构造单元则存在明显的差异，204Pb-207Pb／206Pb，204Pb-208Pb／206Pb图解研究表明，该岩体群为下地壳源花岗岩类，Nd同位素特征（tDN和εNd（t））表明，耀岭河群最适合于作为岩体群的主要物源。该岩体群和耀岭河群的Sr同位素存在一定的差别，这可能是由于南秦岭在280－200Ma间强烈的地质作用使Rb－Sr同位素体系改造所致。