On the visual perception of the eyes in adult Hyalomma truncatum ticks (Acari: Ixodidae)

Adult Hyalomma truncatum ticks with uncovered and foil-covered eyes were exposed to an upright-positioned rectangle as a target giving a luminance contrast ratio of 5:1 at a sun-simulating radiation. The transmission rate of the foil was less than 0.003%. Significantly (p0.05) more locomotorally active ticks with uncovered eyes (36.6%) responded to the target than ticks with foil-covered eyes (7.3%). When the rectangle was illuminated by monochromatic light at wavelengths ranging between 420 and 648 nm, the target induced a positive scototaxis in ticks with uncovered eyes regardless of the wavelength range. In contrast, ticks with covered eyes did not exhibita positive scototaxis at wavelength ranges of 553–585 and 608–648 nm and very few ticks responded only to other wavelength ranges. The results indicate that the eyes are the only or at least the most essential sense organs in the visual system of adult H. truncatum ticks.     

Differences between attractive diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), sex pheromone lures are not determinable through analysis of emissions

1 Conjoint comparisons were made between trap captures of male diamondback moths, Plutella xylostella (L.), and gas chromatographic measures of sex pheromone emissions from grey and red rubber septa. The objective was to correlate trap captures with emissions. 2 Irrespective of their composition, all mixtures that were released from grey septa effected the capture of more males than the same mixtures released from red septa. There was no difference between captures by any of the mixtures when emitted from grey septa. However, when emitted from red septa, a nominal 50 : 50 ratio of (Z)-11-hexadecenal (Z11–16:Al) and (Z)-11-hexadecenyl acetate (Z11–16:Ac) effected the capture of more males than either nominal 70 : 30 or 67 : 23 ratios. Generally, the emitted ratios of Z11–16:Al and Z11–16:Ac from both types of septa were variable, ranging between 6 : 10 to about 40 : 10. 3 No statistical correlation was found between the emissions and trap captures by any single component, group or ratio of components. These results suggest that the environment substantially affects the emission of sex pheromone components from rubber septa. As a result, the demonstration of geographical biotypes of diamondback moths and other insects may be difficult.     

Incidence of Threat in Dreams: A Response to Revonsuo's Threat Simulation Theory.

A. Revonsuo (2000b) proposed an evolutionary theory of dreaming, stating it is a threat simulation mechanism that allowed early humans to rehearse threat perception and avoidance without biological cost. The present study aimed to establish the proportion of dreams containing physical threats to the dreamer, whether these represent realistic life-threatening events, and whether the dreamer successfully and realistically escapes. It also examined incidence of threatening events in real life. A sample of most recent dreams was collected (N = 401). Only 8.48% of dreamers reported realistic life-threatening events in dreams and a realistic escape subsequently occurred in only one third of these reports. Actual severe life-threatening events were experienced by 44.58% of the sample. These findings contradict key aspects of Revonsuo's theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Observations on graphing paleozoological data: Suggestions for better graphs

Paleozoologists have long used graphs of diverse styles to describe, analyze, and summarize their data. Some of these graphs provide excellent visual representations of complex data and are readily deciphered. Other graph styles require close study to be interpreted. Ease of visual decoding of information contained in a graph – graph perception – varies from graph style to graph style. Historical instances of graphing paleozoological data indicate some difficult to decipher graph styles have been used for at least a century. Graphs with three-dimensions, moiré effects, superimposed lines, or segmented bars, or which demand simultaneous decipherment of position and magnitude, are ill-advised. Temporal trends in data are best graphed following the principle of superposition such that data from old material is graphed at the bottom and data from younger material is graphed at the top of the diagram.     

高寒生态脆弱区农户对气候变化的感知与适应意向——以甘南高原为例

以地处青藏高原东缘的甘南高原为研究区,基于农户调查数据,分析了农户的气候变化感知对其适应意向的影响,为制定有效的气候变化适应政策提供依据.结果表明: 纯农户、兼业户、非农户对气候变化的严重性的感知依次降低,但适应功效感知依次增强,且与非农户、纯农户相比,兼业户的可能性感知、自我效能感知与适应成本感知均较高;纯农户、兼业户、非农户对气候变化的积极适应意向趋于增强;气候变化风险感知、适应功效感知促使农户产生积极适应意向,而适应成本感知促使其产生消极适应意向.同时,农户拥有的耕地面积、牲畜数量、收入水平以及性格乐观程度与积极适应意向发生概率呈显著正相关,而固定资产拥有量、无偿现金援助机会、亲戚网及帮助网规模与其呈显著负相关.最后,提出了促使农户产生积极适应意向的对策建议及未来研究中需关注的问题.     

Gravitropism of hypocotyls of wild-type and starch-deficient Arabidopsis seedlings in spaceflight studies

The major purpose of this spaceflight project was to investigate the starch-statolith hypothesis for gravity perception, and a secondary goal was to study plant growth and development under spaceflight conditions. This research was based on our ground studies of gravity perception in the wild type and three starch-deficient (one starchless and two reduced starch) mutants of Arabidopsis thaliana (L.) Heynh. Dark-grown seedlings that developed in microgravity were given one of several (30 min, 60 min, or 90 min) 1-g stimuli by an on-board centrifuge, and additional controls for seedling development also were performed. These latter control experiments included a morphological study of plants that developed in space in microgravity (F μg), in space on a centrifuge (F 1g), on the ground (G 1g), and on a rotating clinostat on the ground. Since elevated levels of ethylene were reported in the spacecraft atmosphere, additional controls for morphology and gravitropism with added ethylene also were performed. While exogenous ethylene reduced the absolute magnitude of the response in all four strains of Arabidopsis, this gas did not appear to change the relative graviresponsiveness among the strains. The relative response of hypocotyls of microgravity-grown seedlings to the stimuli provided by the in-flight centrifuge was: wild type > starch-deficient mutants. Although the protoplast pressure model for gravity perception cannot be excluded, these results are consistent with a statolith-based model for perception in plants. Received: 12 February 1999 / Accepted: 9 March 1999     

Incorporating Motion into Investigations of mimicry

During the past thirty years, natural selection due to predation has been investigated with regard to prey motion in three areas that are relevant to the evolution of mimicry: (1) anti-apostatic selection, (2) locomotor mimicry, and (3) escape mimicry. Anti-apostatic selection, or selection against the odd individuals, arises when prey are at very high densities or when prey are Müllerian mimics. When prey are at high densities, motion of the prey increases selection against odd individuals. When the prey are Müllerian mimics, motion may also play an important role in strengthening selection against odd individuals. This may explain locomotor mimicry between Müllerian mimics. Locomotor mimicry arises when two distantly-related prey species appear alike in behaviour, and there is a corresponding suite of morphological, physiological, and biomechanical traits that the prey have in common. Locomotor mimicry has been demonstrated in Müllerian mimics. It is also predicted to occur in Batesian mimics but with important limitations due to selection by the predator for the prey to maintain the ability to escape if detected. Locomotor mimicry may also occur between palatable species that are alike as a result of unprofitable prey (or escape) mimicry. Escape mimicry arises when prey are difficult to capture. By frustration learning, the predator associates the colour of the prey with unprofitability. In all three instances, dis-similarity in colour or motion probably increases selection against the odd individual. In addition, the interaction of colour and motion gives rise to greater reliability of the signals to a specialist predator. However for a generalist predator, multiple component signals of the prey lead to errors in signal perception and greater risk of cheating. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ontogeny and stability of separation and threat-induced defensive behaviors in rhesus monkeys during the first year of life

Twenty-six rhesus monkeys were tested repeatedly at 4, 8, and 12 months of age to characterize the expression and development of their defensive responses induced by separation from their mothers and exposure to a potential threat. Results demonstrated that by 4 months of age infant monkeys engaged in adult-like context-dependent responses and adaptively regulated these responses in relation to the changing context. When separated from their mothers and alone, infants at 4 months of age were active and emitted frequent coo vocalizations. However, when exposed to the profile of a human face, infants responded by becoming behaviorally inhibited and freezing. At 8 months of age, a dramatic reduction in infants' separation-induced coos was observed, whereas their duration of threat-induced freezing remained unchanged. At 12 months of age, a further decrease in cooing occurred, while freezing duration was maintained. No sex differences were found in the expression of these behaviors or their developmental patterns. Individual differences in separation-induced cooing and threat-induced freezing were apparent and remained stable over the three ages studied. However, within animals no relation was found between individual differences in cooing and freezing. These data demonstrate important differences in the developmental patterns for the expression of cooing and freezing over the first year of life. Marked individual differences in separation-induced cooing and threat-induced freezing were apparent and remained stable from 4–12 months of age. The data support the hypothesis that these different defensive responses reflect different adaptive responses that likely have different underlying mechanisms. The similarities between these defensive responses in rhesus monkeys and humans suggests that understanding the factors that promote the development of individual differences in monkeys will illuminate important factors that promote individual differences in humans. Am. J. Primatol. 44:125–135, 1998. ©1998 Wiley-Liss, Inc.     

Dogs' looking times and pupil dilation response reveal expectations about contact causality

Contact causality is one of the fundamental principles allowing us to make sense of our physical environment. From an early age, humans perceive spatio-temporally contiguous launching events as causal. Surprisingly little is known about causal perception in non-human animals, particularly outside the primate order. Violation-of-expectation paradigms in combination with eye-tracking and pupillometry have been used to study physical expectations in human infants. In the current study, we establish this approach for dogs (Canis familiaris). We presented dogs with realistic three-dimensional animations of launching events with contact (regular launching event) or without contact between the involved objects. In both conditions, the objects moved with the same timing and kinematic properties. The dogs tracked the object movements closely throughout the study but their pupils were larger in the no-contact condition and they looked longer at the object initiating the launch after the no-contact event compared to the contact event. We conclude that dogs have implicit expectations about contact causality.