Sequential assessment of prey through the use of multiple sensory cues by an eavesdropping bat

Predators are often confronted with a broad diversity of potential prey. They rely on cues associated with prey quality and palatability to optimize their hunting success and to avoid consuming toxic prey. Here, we investigate a predator’s ability to assess prey cues during capture, handling, and consumption when confronted with conflicting information about prey quality. We used advertisement calls of a preferred prey item (the túngara frog) to attract fringe-lipped bats, Trachops cirrhosus, then offered palatable, poisonous, and chemically manipulated anurans as prey. Advertisement calls elicited an attack response, but as bats approached, they used additional sensory cues in a sequential manner to update their information about prey size and palatability. While both palatable and poisonous small anurans were readily captured, large poisonous toads were approached but not contacted suggesting the use of echolocation for assessment of prey size at close range. Once prey was captured, bats used chemical cues to make final, post-capture decisions about whether to consume the prey. Bats dropped small, poisonous toads as well as palatable frogs coated in toad toxins either immediately or shortly after capture. Our study suggests that echolocation and chemical cues obtained at close range supplement information obtained from acoustic cues at long range. Updating information about prey quality minimizes the occurrence of costly errors and may be advantageous in tracking temporal and spatial fluctuations of prey and exploiting novel food sources. These findings emphasize the sequential, complex nature of prey assessment that may allow exploratory and flexible hunting behaviors.     

Phase relations between a circadian rhythm and its zeitgeber within the range of entrainment

The regular day-night changes in tissues, physiologic functions, and behavior of organisms are based on endogenous rhythmic processes which under constant conditions continue with periods slightly deviating from 24h. These ‘arcadian’ rhythms have properties of self-sustained oscillators. Under natural conditions, circadian rhythms are synchronized (entrained) to 24 h by periodic factors in the environment, the so-called ‘Zeitgebers’. In the laboratory, circadian rhythms can also be entrained to periods other than 24 h within certain limits. Data on the phase relationship between the circadian rhythm and an entraining light-dark cycle for vertebrates, insects, plants, and unicellular organisms are reviewed.     

From repulsion to attraction: species- and spatial context-dependent threat sensitive response of the spider mite Tetranychus urticae to predatory mite cues

Prey perceiving predation risk commonly change their behavior to avoid predation. However, antipredator strategies are costly. Therefore, according to the threat-sensitive predator avoidance hypothesis, prey should match the intensity of their antipredator behaviors to the degree of threat, which may depend on the predator species and the spatial context. We assessed threat sensitivity of the two-spotted spider mite, Tetranychus urticae, to the cues of three predatory mites, Phytoseiulus persimilis, Neoseiulus californicus, and Amblyseius andersoni, posing different degrees of risk in two spatial contexts. We first conducted a no-choice test measuring oviposition and activity of T. urticae exposed to chemical traces of predators or traces plus predator eggs. Then, we tested the site preference of T. urticae in choice tests, using artificial cages and leaves. In the no-choice test, T. urticae deposited their first egg later in the presence of cues of P. persimilis than of the other two predators and cue absence, indicating interspecific threat-sensitivity. T. urticae laid also fewer eggs in the presence of cues of P. persimilis and A. andersoni than of N. californicus and cue absence. In the artificial cage test, the spider mites preferred the site with predator traces, whereas in the leaf test, they preferentially resided on leaves without traces. We argue that in a nonplant environment, chemical predator traces do not indicate a risk for T. urticae, and instead, these traces function as indirect habitat cues. The spider mites were attracted to these cues because they associated them with the existence of a nearby host plant.     

Social Vulnerability to Climate Change and the Architecture of Entitlements

The objective of this paper is to outline a conceptual model of vulnerability to climate change as the first step in appraising and understanding the social and economic processes which facilitate and constrain adaptation. Vulnerability as defined here pertains to individuals and social groups. It is the state of individuals, of groups, of communities defined in terms of their ability to cope with and adapt to any external stress placed on their livelihoods and well-being. This proposed approach puts the social and economic well-being of society at the centre of the analysis, thereby reversing the central focus of approaches to climate impact assessment based on impacts on and the adaptability of natural resources or ecosystems and which only subsequently address consequences for human well-being. The vulnerability or security of any group is determined by the availability of resources and, crucially, by the entitlement of individuals and groups to call on these resources. This perspective extends the concept of entitlements developed within neo-classical and institutional economics. Within this conceptual framework, vulnerability can be seen as a socially-constructed phenomenon influenced by institutional and economic dynamics. The study develops proxy indicators of vulnerability related to the structure of economic relations and the entitlements which govern them, and shows how these can be applied to a District in coastal lowland Vietnam. This paper outlines the lessons of such an approach to social vulnerability for the assessment of climate change at the global scale. We argue that the socio-economic and biophysical processes that determine vulnerability are manifest at the local, national, regional and global level but that the state of vulnerability itself is associated with a specific population. Aggregation from one level to another is therefore not appropriate and global-scale analysis is meaningful only in so far as it deals with the vulnerability of the global community itself.     

Social experience influences the development of a central auditory area

Vocal communication develops under social influences that can enhance attention, an important factor in memory formation and perceptual tuning. In songbirds, social conditions can delay sensitive periods of development, overcome learning inhibitions and enable exceptional learning or induce selective learning. However, we do not know how social conditions influence auditory processing in the brain. In the present study, we raised young naive starlings under different social conditions but with the same auditory experience of adult songs, and we compared the effects of these different conditions on the development of the auditory cortex analogue. Several features appeared to be influenced by the social experience, among which the proportion of auditory neuronal sites and the neuronal selectivity. Both physical and social isolation from adult models altered the development of the auditory area in parallel to alterations in vocal development. To our knowledge, this is the first evidence that social deprivation has as much influence on neuronal responsiveness as sensory deprivation.     

抓好公民道德教育 促进社会生产力发展

本文概述了社会公德对生产力发展所起到的重要作用,并探讨了公民道德教育的重要意义以及主要措施。     

城镇发展的可持续性评价方法及其应用

采用多目标评价方法构建以发展度、协调度和支撑度为评价指标的评价模型,对城镇发展的可持续性进行评价.运用层次分析法,从人口、社会和经济等方面建立评价指标体系,评估人工生态系统的发展度和协调度,将资源和环境状况作为支撑度指标评估自然生态系统的可持续性,进而计算城镇发展的综合可持续性水平.以福建省铁山镇为例,应用该模型进行评价.结果表明,铁山镇发展的可持续性水平为0.617(取值范围0～1),属于中等可持续水平,水环境污染是最主要的瓶颈因素.该评价方法可以辨识城镇发展的可持续性,为城镇产业发展的方向和规模等提供决策依据.