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2.
Previous ecological studies of Palearctic passerine migrants in Africa have claimed to reveal some general features with respect to habitat use, foraging ecology and interspecific relationships with Afrotropical residents. In this review we discuss apparent contradictions between earlier generalisations and more recent results from more detailed field studies and explore in which areas our ecological knowledge and theoretical understanding remain poor and have given rise to misconceptions. For example, it has been claimed that migrants use structurally more diverse and open habitats and that they forage higher and in more peripheral parts of the vegetation than their ecologically similar Afrotropical counterparts, yet in the past these characteristics were often not clearly defined and not always correlated in practice. It has also been stated that migrants are more flexible in habitat use, occupying a wider range of habitat types and employing a higher diversity of foraging techniques, both of which were assumed to be adaptations to permit coexistence with Afrotropical residents by using untapped resources that are only seasonally available. Yet results from studies of the role of competition in shaping migrant-resident communities remain largely unconvincing. While flexibility may facilitate migrant-resident coexistence, it may also favour the evolution of migration because specialists are less able to use their advantages in different environments. We note that definitions of flexibility and specialisation may themselves depend on the ecological or evolutionary approach adopted by researchers. We conclude that few generalisations can safely be made about the ecology of Palearctic migrants in Africa and that adaptive explanations for the behaviours observed are largely lacking, as are studies of the fitness consequences of different migrant strategies such as have been conducted in the Nearctic-Neotropical migration system. 相似文献
3.
In many anurans, the pelvic patch of the ventral skin and the urinary bladder are important osmoregulatory organs. Since the discovery of water channel protein, aquaporin (AQP), in mammalian erythrocytes, 17 distinct full sequences of AQP mRNAs have been identified in anurans. Phylogenetic tree of AQP proteins from amphibians and mammals suggested that anuran AQPs can be divided into six types: i.e. types 1, 2, 3, and 5, and anuran-specific types a1 and a2. Among them, two types of anuran AQPs (types 1 and a2) are localized in the skin and urinary bladder by immunohistochemistry. Tree frog type-a2 AQPs, AQP-h2 and AQP-h3, are vasotocin-regulated water channels predominant in the osmoregulatory organs. Both the AQP-h2 and AQP-h3 are expressed at the granular cells underneath the keratinized layer in the pelvic patch, whereas only AQP-h2 is detected at the granular cells in the urinary bladder. In response to vasotocin, both the molecules seem to be translocated from the cytoplasmic pool to the apical plasma membrane of the granular cells. On the other hand, type-1 AQPs, Rana FA-CHIP and Hyla AQP-h1, are detected at the endothelial cells of blood capillaries in frog osmoregulatory organs. These findings suggest that AQP-h2 and AQP-h3 are key players for transepithelial water movement, and that FA-CHIP and AQP-h1 might be important for the transport of absorbed water into the blood flow. Comparative investigation of type-a2 AQPs in anurans further revealed that AQP-h2 and -h3-like molecules might exist at the urinary bladder and the pelvic skin, respectively, in various anurans from aquatic species to arboreal dwellers. AQP-h2-like protein is also detected in the pelvic skin of terrestrial and arboreal species. It is possible that this molecule might have occurred in the pelvic skin as anurans penetrated into drier environments. 相似文献
4.
In addition to seasonal changes in morphology, physiology and behaviour that occur in predictable annual cycles, there are facultative responses to unpredictable events known as labile (i.e. shortlived) perturbation factors. These rapid behavioural and physiological changes have been termed the ‘emergency life-history stage’ and serve to enhance lifetime fitness. There are four major components: (1) proactive/reactive coping styles for responding to psychosocial stress, predation, and so forth; (2) fight-or-flight responses to rapid emergencies such as an attack by a predator or sudden severe storm; (3) ‘take-it-or-leave-it’ behavioural and physiological responses to longer-term perturbations of the physical environment; and (4) sickness behaviour and fever designed to respond to infection. Glucocorticosteroids interact with cytokines and with other hormones in the hypothalamo-pituitary-adrenal cascade and in the autonomic nervous system to initiate and orchestrate the emergency life-history stage within minutes to hours. Some traits of the emergency life-history stage include: redirection of behaviour from a normal life-history stage to increased foraging, irruptive-type migration during the day, enhanced restfulness at night, elevated gluconeogenesis, and recovery once the perturbation passes. These physiological and behavioural changes allow an individual to avoid potential deleterious effects of stress that may result from chronically elevated levels of circulating glucocorticosteroids over days and weeks. Thus, acute rises in glucocorticosteroids following perturbations of the environment may serve primarily as ‘antistress’ hormones, potentially allowing individuals to avoid chronic stress. Several field studies in diverse habitats indicate that individuals in free-living populations show elevated circulating levels of corticosteroids when they are in an emergency life-history stage. Some simple models based on food availability, body condition, social status and life-history stage, may allow predictions of sensitivity of the hypothalamo-pituitary-adrenal axis to labile perturbation factors. Although there is now extensive evidence for behavioural components of the emergency life-history stage in birds, there remains much to be learned about how other vertebrate groups, especially fish, cope with perturbations of the environment. Because of the unpredictable nature of these perturbations, systematic study of behavioural responses to them is not possible and investigators need to be ‘opportunistic’. There is also a growing need to expand our knowledge of these phenomena because human disturbance, global climate change and pollution are all major perturbations of the environment. How vertebrates respond to the unpredictable in general will thus have important conservation value for the future. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. 相似文献
6.
With the exception of a few model species, individual differences in cognition remain relatively unstudied in non-human animals. One intriguing possibility is that variation in cognition is functionally related to variation in personality. Here, we review some examples and present hypotheses on relationships between personality (or behavioural syndromes) and individual differences in cognitive style. Our hypotheses are based largely on a connection between fast-slow behavioural types (BTs; e.g. boldness, aggressiveness, exploration tendency) and cognitive speed-accuracy trade-offs. We also discuss connections between BTs, cognition and ecologically important aspects of decision-making, including sampling, impulsivity, risk sensitivity and choosiness. Finally, we introduce the notion of cognition syndromes, and apply ideas from theories on adaptive behavioural syndromes to generate predictions on cognition syndromes. 相似文献
7.
Summary Ecological research in Scotland during the four decades since the publication of Burnett's (1964) volume has characterized the diversity of alpine vegetation in Scotland. There has been less progress in understanding the structural and functional roles of plant species in Scottish alpine ecosystems. Areas for future research in Scottish alpine vegetation are discussed in terms of the causes of patterns in biodiversity and the factors likely to influence these. The potential role of Scottish alpine vegetation as a biogeographic extreme for comparison in larger scale studies is outlined. 相似文献
8.
Evidence supporting a key role for anaerobic methane oxidation in the global methane cycle is reviewed. Emphasis is on recent
microbiological advances. The driving force for research on this process continues to be the fact that microbial communities
intercept and consume methane from anoxic environments, methane that would otherwise enter the atmosphere. Anaerobic methane
oxidation is biogeochemically important because methane is a potent greenhouse gas in the atmosphere and is abundant in anoxic
environments. Geochemical evidence for this process has been observed in numerous marine sediments along the continental margins,
in methane seeps and vents, around methane hydrate deposits, and in anoxic waters. The anaerobic oxidation of methane is performed
by at least two phylogenetically distinct groups of archaea, the ANME-1 and ANME-2. These archaea are frequently observed
as consortia with sulfate-reducing bacteria, and the metabolism of these consortia presumably involves a syntrophic association
based on interspecies electron transfer. The archaeal member of a consortium apparently oxidizes methane and shuttles reduced
compounds to the sulfate-reducing bacteria. Despite recent advances in understanding anaerobic methane oxidation, uncertainties
still remain regarding the nature and necessity of the syntrophic association, the biochemical pathway of methane oxidation,
and the interaction of the process with the local chemical and physical environment. This review will consider the microbial
ecology and biogeochemistry of anaerobic methane oxidation with a special emphasis on the interactions between the responsible
organisms and their environment.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
The development of more efficient and cost-effective oestrous detection techniques for cattle depends on a thorough understanding of the changes in behaviour and physiology of the female during its oestrous cycle. Variability in the expression of oestrous behaviours both between individuals and over successive oestrous cycles complicates this process. This review considers many of the biological and environmental factors that influence the intensity and duration of oestrous behaviours in domestic cattle. Topics discussed include dominant-subordinate relationships, social facilitation, animal density, oestrous synchronisation, nutritional status, age and physiological state, presence of the bull and breed differences. Facility design, cattle management and various techniques used to detect oestrus (e.g. frequency, duration and timing of observations) directly influence the efficiency of oestrous detection programs. Environmental phenomena such as weather, day length, photoperiod and ambient temperature also affect the expression of oestrous behaviours. 相似文献
10.
There is growing interest in research and development to develop novel tools to study, detect, and characterize microbes
and their communities in industrial environments. However, knowledge about their validity in practical industrial use is still
scarce. This review describes the advantages and limitations of traditional and molecular methods used for biofilm and/or
planktonic cell studies, especially those performed with Listeria monocytogenes, Bacillus cereus, and/or Clostridium perfringens. In addition, the review addresses the importance of isolating the microorganisms from the industrial environment and the
possibilities and future prospects for exploiting the described methods in the industrial environment. 相似文献
11.
In recent years, cloud computing can be considered an emerging technology that can share resources with users. Because cloud computing is on-demand, efficient use of resources such as memory, processors, bandwidth, etc., is a big challenge. Despite the advantages of cloud computing, sometimes it is not a proper choice due to its delay in responding appropriately to existing requests, which led to the need for another technology called fog computing. Fog computing reduces traffic and time lags by expanding cloud services to the network and closer to users. It can schedule resources with higher efficiency and utilize them to impact the user's experience dramatically. This paper aims to survey some studies that have been done in the field of scheduling in fog/cloud computing environments. The focus of this survey is on published studies between 2015 and 2021 in journals or conferences. We selected 71 studies in a systematic literature review (SLR) from four major scientific databases based on their relation to our paper. We classified these studies into five categories based on their traced parameters and their focus area. This classification comprises 1—performance 2—energy efficiency, 3—resource utilization, 4—performance and energy efficiency, and 5—performance and resource utilization simultaneously. 42.3% of the studies focused on performance, 9.9% on energy efficiency, 7.0% on resource utilization, 21.1% on both performance and energy efficiency, and 19.7% on both performance and resource utilization. Finally, we present challenges and open issues in the resource scheduling methods in fog/cloud computing environments. 相似文献
13.
We review published records of laboratory experiments on peripatric and vicariance allopatric speciation to address the following three questions: (1) What was the true effect size of reproductive isolation? (2) Was the reproductive isolation persistent? (3) What influenced the development of isolation? Contrary to popular belief, laboratory evidence for allopatric speciation is quite weak. Assortative mating was only found among derived populations in vicariance experiments. Reproductive isolation against control populations was only intermittent, so there is reason to doubt if some cases showing significant reproductive isolation really should be attributed to speciation. The method of testing was at least as important as the speciation model. Experimental populations tested against each other were the most likely to demonstrate reproductive isolation. This study suggests that allopatric speciation experiments are more likely to yield conclusive results under divergent selection than under drift, and points to the benefits of large populations and many generations. 相似文献
15.
The development of social behaviour was studied in three natural populations of Bighorn sheep ( Ovis canadensis ). Individuals in all populations exhibited the same behavioural repertoires, but the utilization of specific behaviours among both infants and adults differed between populations. It was suggested that differences in the adult utilization of behaviour patterns result in part from behaviours used during infancy. In turn, the social and physical environments affected the development of subsequent behaviour patterns in sheep older than lambs. Desert sheep (in southern California) used mounting behaviours often, presumably because they matured sexually at an early age. Sheep in a more northern environment (British Columbia) used different behaviour patterns more frequently perhaps as a consequence of interactions experienced in larger bands. Additionally, playful interactions were reduced due to physical hazards in the desert, but they were at least nine times as frequent in the northern study population. Play in large groups resulted in the utilization of more different kinds of behaviour patterns. These behavioural findings are interpreted ecologically as consequences of inhabiting environments that differ socially and physically. 相似文献
16.
Systematically review and analyse the efficacy of CBT versus treatment as usual in adults with ADHD. The literature was systematically searched ending the 28 March 2014. Standardised mean differences (SMD) and 95 % confidence intervals were calculated. CBT was efficacious in reducing symptoms of ADHD (SDM ?1.0, 95 % CI ?1.5 to ?0.5) when evaluated by the patients, but not when evaluated by a clinician. Symptoms of depression and anxiety were significantly reduced when self-reported (SMD ?1.0, 95 % CI ?1.6 to ?0.5 and ?1.0, 95 % CI ?1.3 to ?0.3, respectively) and evaluated by a clinician (SMD ?0.9, 95 % CI ?1.7 to ?0.2 and ?0.9, 95 % CI ?1.6 to ?0.1). The clinical global impression scores improved more in the group randomised to CBT (?1.0; 95 % CI ?1.6 to ?0.4). CBT seems efficacious in some domains affecting adult patients with ADHD, but needs further evaluation. 相似文献
17.
The conservation status of all the amphibians in China is analyzed, and the country is shown to be a global priority for conservation in comparison to many other countries of the world. Three Chinese regions are particularly rich in amphibian diversity: Hengduan, Nanling, and Wuyi mountains. Salamanders are more threatened than frogs and toads. Several smaller families show a high propensity to become seriously threatened: Bombinatoridae, Cryptobranchidae, Hynobiidae and Salamandridae. Like other parts of the world, stream-breeding, high-elevation forest amphibians have a much higher likelihood of being seriously threatened. Habitat loss, pollution, and over-harvesting are the most serious threats to Chinese amphibians. Over-harvesting is a less pervasive threat than habitat loss, but it is more likely to drive a species into rapid decline. Five conservation challenges are mentioned with recommendations for the highest priority research and conservation actions. 相似文献
19.
FRAME and the University of Nottingham have been in association for the past 25 years. During this time, the research in the FRAME Alternatives Laboratory (FAL) at the University of Nottingham, which is partly funded by FRAME and also, more recently, by ECVAM, has involved participation in a number of international validation studies. Validation has become a pre-requisite for the regulatory acceptance of in vitro alternative test procedures, and a number of key lessons have been learned from these studies. The directors of validation studies need to ensure that standard operating procedures (SOPs) are fully complied with, and that the equipment used is certified to be of an acceptable standard. Database managers need to be able to check the original data, and to ensure adherence to procedures agreed before the study began. When the validation study is part of an integrated EU Framework Project, such as ACute-Tox, the Workpackage Leader must have the ability to understand and evaluate the data to be presented for inclusion in the study analysis, and to check that it complies with acceptance criteria. The potential to relate observed cellular biochemical changes to morphological endpoints also increases the level of understanding of the relevance and/or limitations of an assay. For example, exposure to a surfactant can induce the temporary loss of adhesion junctions between adjacent epithelial cells, resulting in the loss of barrier integrity and other effects on cell culture activity, which can potentially be restored over time. Unexpected results from the NRU phototoxicity assay with human keratinocytes instead of 3T3 cells, stimulated research into the ability of the in vitro assay, not only to identify phototoxins, but also to identify their possible mechanisms of action and mechanisms underlying the protective capacity within human primary keratinocytes in vitro. The protective effects of UV-filters can also be used to ascertain their effects on the photoactivation of drugs. 相似文献
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