Landmark cues can change the motivational state of desert ant foragers

Desert ants of the genus Cataglyphis rely on path integration vectors to return to the nest (inbound runs) and back to frequently visited feeding sites (outbound runs). If disturbed, e.g., experimentally displaced on their inbound runs, they continue to run off their home-bound vector, but if disturbed in the same way on their outbound runs, they do not continue their feeder-based vector, but immediately switch on the home-bound state of their path integration vector and return to the nest. Here we show that familiar landmarks encountered by the ants during their run towards the feeder can change the ants’ motivational state insofar that the ants even if disturbed continue to run in the nest-to-feeder direction rather than reverse their courses, as they do in landmark-free situations. Hence, landmark cues can cause the ants to change their motivational state from homing to foraging.     

Regulation of the biosynthesis of ergot alkaloids byPenicillium sizovae

To investigate the regulation of the biosynthesis of ergot alkaloids by end products, the effect of exogenous agroclavine-1 and epoxyagroclavine-1 on their accumulation byP. sizovae was studied. The added alkaloids stimulated considerably their own biosynthesis depending on their concentration and time of introduction. The stimulating effect of both alkaloids and products of their degradation was suggested. Exogenous agroclavine-1 and epoxyagroclavine-1 changed the relation between the quantities of intra-and extracellular alkaloids, thus pointing to their possible influence on the transport processes.     

When the Curtain Falls on a Fieldwork Project: The Last Chapter of a Gay Synagogue Study

Ethnographic texts preserve the historicity and losses of both the people observed and their observer. However, anthropologists rarely inform their readers about the circumstances of their departure from a fieldwork project. Without formally indicating the completion of their research goals, they usually move on to a new field and cease publishing on their former site. This procedure seemed natural enough when anthropologists conducted their studies in remote Third World locations. The constraints of distance, time, and budget made that abrupt separation seemingly inevitable and self-explanatory. But when anthropologists choose fieldwork sites that are close to home or easy to revisit, or conduct long-term research, their relationships with their subjects change radically, both during fieldwork and during the stages of writing and publishing the ethnographic text. Consequently, their eventual exit from the field involves a different process. Based on the experience of a fifteenyear engagement in the study of a gay synagogue in New York, this paper explores the latter process. The issue of exiting presents a methodological, emotional, and ethical problem meriting serious professional consideration.     

Wolbachia属共生菌及其对节肢动物宿主适合度的影响

Wolbachia是广泛分布于节肢动物体生殖组织内呈母质遗传的一类共生细菌。近30多年来,大量的研究主要集中于Wolbachia对宿主生殖方式的调控方面;近年来的研究发现,Wolbachia对节肢动物宿主的适合度具有不同程度的影响。现对Wolbachia的宿主分布、存在部位及其对节肢动物宿主种群适合度的影响等方面进行了综述,探讨了Wolbachia在该领域的研究意义和潜在的应用价值。     

Effect of Adult Feeding on Male Mating Behaviour in the Butterfly, <Emphasis Type="Italic">Bicyclus anynana</Emphasis> (Lepidoptera: Nymphalidae)

Many species of lepidopterans supplement their nectar diet with foods rich in nitrogen and minerals, which are present only in trace amounts in nectar. We examined the effect of adult diet on mating behaviour and spermatophore characteristics in male Bicyclus anynana (Butler, 1879) butterflies, which feed on rotten fruits as adults. We found little effect of adult diet on male reproduction in terms of mating rate and sperm production, although males fed on fruit produced larger spermatophores on their first mating compared to males fed sugar only. We also examined how males allocate sperm across matings. Males ejaculate larger spermatophores during their first mating, and produce spermatophores containing decreasingly fewer non-fertile sperm with number of matings performed. Males that produced more non-fertile sperm on their first mating had reduced lifespan possibly indicating a trade-off between sperm production and adult longevity. It is suggested that adult diet has little affect on male ejaculate production and males feed on fruit to supplement their energetic carbon requirements.     

Stresses on the limbs of quadrupedal primates

Data is presented from eight primates on the ground reaction forces on the limbs during locomotion. These subjects supported from 30 to 45% of their body weight on their forelimbs. Other quadrupedal mammals support 55-60% of their body weight on their forelimbs. The increase of peak vertical force with speed varies greatly between the subjects. The variation in weight supported by the forelimbs and the peak forces on the forelimbs is proposed to correlate with variation in locomotor adaptations. It is suggested that the occurrence of bipedalism in primates represents the extreme expression of the tendency in primates to reduce the compressive forces on their forelimbs.     

饲喂雌鼠大豆异黄酮对后代雌性生殖性状的影响

目的研究雌性小鼠饲喂异黄酮后对其后代雌鼠生殖性状的影响。方法分别在雌鼠从断奶到妊娠前和妊娠期间两个不同阶段的日粮中添加不同剂量的大豆异黄酮（0、50、400 mg/kg）。记录F1代的出生窝产仔数、出生窝重、雌鼠的阴道最早开张时间和最早见栓时间,以及后代雌鼠性成熟期和体成熟期生殖器官重量、血清雌激素的含量。结果雌鼠妊娠期饲喂含50、400 mg/kg大豆异黄酮的饲料后F1代的窝产仔数显著高于对照组（P〈0.05）;雌鼠妊娠期采食400 mg/kg大豆异黄酮饲料,其后代雌鼠初次配种时间明显延迟（P〈0.05）;45、65日龄体重显著低于对照组,65日龄子宫重显著低于对照组,卵巢重显著高于对照组;血清中雌激素含量显著低于对照组（P〈0.05）,妊娠期间采食50 mg/kg大豆异黄酮饲料,其F1代雌鼠仅窝产仔数和45日龄时血清中雌激素含量受到影响;而雌鼠从断奶到怀孕期间饲喂含大豆异黄酮饲料的F1代在各项指标与对照组均差异无显著性。结论雌鼠妊娠期间饲喂含400 mg/kg大豆异黄酮的饲料会显著影响其雌性后代的初情期、生殖器官发育、血清雌激素含量等生殖生理性状,而在非妊娠期饲喂含大豆异黄酮饲料对F1代无显著影响。     

白蚁肠道共生微生物的作用:酵母,一个“隐身”的特别菌群

长期以来,白蚁对木质纤维素的降解能力令人惊叹,毫无疑问,其在全球碳循环中扮演着一个十分重要的角色。这一强大功能的实现极大地依赖于一种特别的肠道"消化液(digestome)",它的构成不仅包括了来自白蚁自身产生的木质纤维素降解酶系统,还来源于独特与多样的肠道共生微生物的贡献(包括了古细菌、细菌、酵母以及其他真核生物),它们的协同作用能有效地将木质纤维素生物质高效转化为乙酸、甲烷、二氧化碳、氢气等物质。然而,到目前为止,我们对这类昆虫的独特肠道生物转化系统的认识还很不深入,特别是针对肠道内的那些各类共生微生物菌群的功能、白蚁与共生微生物间的相互关系、以及潜在的科学与应用价值还无法给予明确的科学解释,更不用说针对其肠道中的共生酵母菌群,一类通常被忽略的独特微生物。近20多年来,越来越多的研究证据表明,白蚁肠道共生酵母在与寄主的关系中表现了不可或缺的重要性与独特功能,已被证明广泛分布于不同白蚁及许多其他昆虫的肠道中。随着近20年来越来越多昆虫肠道共生微生物酵母群被发现和鉴定,他们潜在的功能以及与寄主的共生机制被逐步解析,这些研究结果进一步揭示了"隐身"的昆虫肠道酵母类微生物菌群与寄主的营养、关键生物质转化过程中的重要酶系统、转化过程中的关键中间产物的转化与利用、抵御外源性的重要病原物,甚至对白蚁种群繁衍的远缘交配等方面均可能发挥了重要和不可缺少的作用。本文将试图归纳相关研究的最新进展,系统总结与解析白蚁肠道来源共生酵母的重要科学价值及其在不同领域的潜在应用前景。     

Medicine and place: an inquiry

This essay explores the various places inhabited by doctors and patients, in order to lead doctors to a more complex understanding of their patients' experiences of illness. Using Adam Haslett's "The Good Doctor" (2002), we examine what happens when doctors enter the worlds of their patients, both the literal landscapes of their patients' homes and the hidden landscapes of their minds. We illustrate the impact place has on doctors' understanding of their patients and on the patients' attitudes toward their illness. In addition, we examine how place informs readers' perceptions of both the coherence and the divide between the worlds of doctor and patient.     

Biological interactions of alpha,beta-unsaturated aldehydes

This article describes the chemical nature of alpha,beta-unsaturated aldehydes and some of their toxicological effects based on their ability to function as direct-acting alkylating agents. Selected compounds discussed include alpha,beta-unsaturated aldehydic environmental pollutants, metabolites of xenobiotics and natural products, and lipid peroxidation--and DNA oxidation products derived from cellular constituents. Briefly reviewed are sources and mechanisms of formation of the aldehydes, their reactivity with respect to glutathione and amino-groups, their toxicity based on interaction with sulfhydryl and amino targets in cells, and modulation of their toxicity by metabolism.     

唐家河自然保护区冬季独栖羚牛及其习性

笔者于1987年冬季至1988年春季对唐家河自然保护区离群的独栖羚牛进行了考察研究,获得了数量、分布及冬季活动规律等资料,并在行为生态、越冬适应及死亡限制因素等方面作了较深入的研究。这些老、弱、病、残羚牛离群而独栖生活,也是羚牛个体发生的必然规律;它们日趋衰弱,濒于死亡的边缘也是必然趋势。     

Mothers' attitudes in infant feeding at Newcastle General Hospital in summer 1975.

Two-hundred successively delivered mothers were asked about their attitudes towards feeding their babies, the influences on them, and their personal and social backgrounds. Initially 39% intended to breast-feed, though in the first few weeks many gave up. Choosing to breast-feed, and success in doing so, were strongly associated with higher social class. The commonest reason given by those who chose the bottle was the embarrassment of breast-feeding. Efforts to increase the numbers of mothers choosing to breast-feed should concentrate on those mothers who remain undecided on their method of feeding. If they are to breast-feed their babies successfully they will need careful advice and support both before and after delivery.     

Can Experience Alter the Avian Annual Cycle? Results of Migration Experiments with Indigo Buntings

Field experiments were conducted during 2 years testing whether premature release on their familiar, perennial breeding territories would cause indigo buntings (Passerina cyanea) to delete spring migration from their annual cycle. In the first year, male buntings were captured on their breeding territories in summer and held indoors for the winter on the photoregime that they would have encountered in nature as fall migrants and winter residents. The following spring they were released at the time buntings begin spring migration from the subtropics. Half were released on their breeding territories, to which they would normally have returned; half were released far to the south. Some of the males released on their territories remained and passed into breeding condition without having migrated, while some of those released to the south returned north to their territories. The results suggest that endogenous or photoperiodic mechanisms controlling the timing and occurrence of migration in this species can be overridden by experience. In the second year we tested alternative explanations for these results. Our second year's results seem to indicate (1) that birds that deleted migration in year one did not do so because of unfavourable weather and (2) that the birds that returned to their breeding sites in year one were actually migrating and not simply retracing their outward journey.     

The Lion King and the Hyaena Queen: large carnivore interactions and coexistence

Interactions among species, which range from competition to facilitation, have profound effects on ecosystem functioning. Large carnivores are of particular importance in shaping community structure since they are at the top of the food chain, and many efforts are made to conserve such keystone species. Despite this, the mechanisms of carnivore interactions are far from understood, yet they are key to enabling or hindering their coexistence and hence are highly relevant for their conservation. The goal of this review is thus to provide detailed information on the extents of competition and facilitation between large carnivores and their impact in shaping their life histories. Here, we use the example of spotted hyaenas (Crocuta crocuta) and lions (Panthera leo) and provide a comprehensive knowledge of their interactions based on meta‐analyses from available literature (148 publications). Despite their strong potential for both exploitation and interference competition (range and diet overlap, intraguild predation and kleptoparasitism), we underline some mechanisms facilitating their coexistence (different prey‐age selection and scavenging opportunities). We stress the fact that prey abundance is key to their coexistence and that hyaenas forming very large groups in rich ecosystems could have a negative impact on lions. We show that the coexistence of spotted hyaenas and lions is a complex balance between competition and facilitation, and that prey availability within the ecosystem determines which predator is dominant. However, there are still many gaps in our knowledge such as the spatio‐temporal dynamics of their interactions. As both species' survival becomes increasingly dependent on protected areas, where their densities can be high, it is critical to understand their interactions to inform both reintroduction programs and protected area management.     

Latitudinal shifts of introduced species: possible causes and implications

This study aims to document shifts in the latitudinal distributions of non-native species relative to their own native distributions and to discuss possible causes and implications of these shifts. We used published and newly compiled data on inter-continentally introduced birds, mammals and plants. We found strong correlations between the latitudinal distributions occupied by species in their native and exotic ranges. However, relatively more non-native species occur at latitudes higher than those in their native ranges, and fewer occur at latitudes lower than those in their native ranges. Only a small fraction of species examined (i.e. <20% of animals and <10% of plants) have expanded their distributions in their exotic range beyond both high- and low-limits of their native latitudes. Birds, mammals and plants tended to shift their exotic ranges in similar ways. In addition, most non-native species (65–85% in different groups) have not reached the distributional extent observed in their native ranges. The possible drivers of latitudinal shifts in the exotic range may include climate change, greater biotic resistance at lower latitudes, historical limitations on ranges in native regions, and the impacts of humans on species distributions. The relatively restricted distribution of most species in their exotic range highlights the great potential of future spread of most introduced species and calls for closely monitoring their directional spread under climate change.     

植物内生菌在生物防治中的应用

从植物内生菌的抗病虫机理及生防作用方面综述了植物内生菌在生物防治中的研究进展,对植物内生菌的抗病虫机理进行了探讨,并展望了植物内生菌在植物保护中的应用前景.     

Do second-generation Asian Americans face a systematic disadvantage in occupational attainment? Comment on Tran,Lee and Huang

ABSTRACT

We critically review and discuss several methodological problems with their analysis. Their definition of the occupational hierarchy is unclear, and their inadequate statistical models exacerbate the vagueness of their results. They ignore gender interactions, and the age range of their target population seems too narrow for their research concerns. Their interpretation of their own statistical findings on occupational attainment is fundamentally flawed although they refuse to acknowledge it. Their reported results cannot be replicated based on the information that they are willing to reveal about their analysis which suggests additional, undisclosed errors. In our reanalysis of their data using more appropriate methods, we find that rather than being systematically disadvantaged, the occupational attainment of most second-generation Asian Americans has either achieved parity with whites or has exceeded them after controlling for age, educational level, and survey year.     

Young Children’s Sensitivity to Their Own Ignorance in Informing Others

Prior research suggests that young children selectively inform others depending on others’ knowledge states. Yet, little is known whether children selectively inform others depending on their own knowledge states. To explore this issue, we manipulated 3- to 4-year-old children’s knowledge about the content of a box and assessed the impact on their decisions to inform another person. Moreover, we assessed the presence of uncertainty gestures while they inform another person in light of the suggestions that children''s gestures reflect early developing, perhaps transient, epistemic sensitivity. Finally, we compared children’s performance in the informing context to their explicit verbal judgment of their knowledge states to further confirm the existence of a performance gap between the two tasks. In their decisions to inform, children tend to accurately assess their ignorance, whereas they tend to overestimate their own knowledge states when asked to explicitly report them. Moreover, children display different levels of uncertainty gestures depending on the varying degrees of their informational access. These findings suggest that children’s implicit awareness of their own ignorance may be facilitated in a social, communicative context.     

The legacy effects of keystone individuals on collective behaviour scale to how long they remain within a group

The collective behaviour of social groups is often strongly influenced by one or few individuals, termed here ‘keystone individuals’. We examined whether the influence of keystone individuals on collective behaviour lingers after their departure and whether these lingering effects scale with their tenure in the group. In the social spider, Stegodyphus dumicola, colonies'' boldest individuals wield a disproportionately large influence over colony behaviour. We experimentally manipulated keystones'' tenure in laboratory-housed colonies and tracked their legacy effects on collective prey capture following their removal. We found that bolder keystones caused more aggressive collective foraging behaviour and catalysed greater inter-individual variation in boldness within their colonies. The longer keystones remained in a colony, the longer both of these effects lingered after their departure. Our data demonstrate that, long after their disappearance, keystones have large and lasting effects on social dynamics at both the individual and colony levels.