Behavioral syndromes: an ecological and evolutionary overview

Recent studies suggest that populations and species often exhibit behavioral syndromes; that is, suites of correlated behaviors across situations. An example is an aggression syndrome where some individuals are more aggressive, whereas others are less aggressive across a range of situations and contexts. The existence of behavioral syndromes focuses the attention of behavioral ecologists on limited (less than optimal) behavioral plasticity and behavioral carryovers across situations, rather than on optimal plasticity in each isolated situation. Behavioral syndromes can explain behaviors that appear strikingly non-adaptive in an isolated context (e.g. inappropriately high activity when predators are present, or excessive sexual cannibalism). Behavioral syndromes can also help to explain the maintenance of individual variation in behavioral types, a phenomenon that is ubiquitous, but often ignored. Recent studies suggest that the behavioral type of an individual, population or species can have important ecological and evolutionary implications, including major effects on species distributions, on the relative tendencies of species to be invasive or to respond well to environmental change, and on speciation rates. Although most studies of behavioral syndromes to date have focused on a few organisms, mainly in the laboratory, further work on other species, particularly in the field, should yield numerous new insights.     

林德曼的营养动力论及其在当前生态学研究中的意义

莱曼德·林德曼1942年发表的论文“生态学的营养动力论”为水生态系统能流研究提出了一个全新的概念,被认为是生态学和湖沼学研究史上的奠基之作,也是生态系统生态学的重要著作。林德曼的研究是从定量上应用Arthur Tansley提出的生态系统概念最早的工作之一,并在几个方面具有开创性。该研究最重要的贡献是为研究营养级之间的相互关系和为比较不同的水生态系统提出了共同的衡量指标(有机物或能流),从而为生态学发展确立了理论取向。林德曼的生态学的营养动力论对当前的生态学研究仍然具有重大的指导意义。     

The role of ecological theory in microbial ecology

Microbial ecology is currently undergoing a revolution, with repercussions spreading throughout microbiology, ecology and ecosystem science. The rapid accumulation of molecular data is uncovering vast diversity, abundant uncultivated microbial groups and novel microbial functions. This accumulation of data requires the application of theory to provide organization, structure, mechanistic insight and, ultimately, predictive power that is of practical value, but the application of theory in microbial ecology is currently very limited. Here we argue that the full potential of the ongoing revolution will not be realized if research is not directed and driven by theory, and that the generality of established ecological theory must be tested using microbial systems.     

Regime changes in ecological systems: an information theory approach

We present our efforts at developing an ecological system index using information theory. Specifically, we derive an expression for Fisher Information based on sampling of the system trajectory as it evolves in the space defined by the state variables of the system, i.e. its state space. The Fisher Information index, as we have derived it, is a measure of system order, and captures the characteristic variation in speed and acceleration along the system's periodic steady-state trajectories. When calculated repeatedly over the system period, this index tracks steady states and transient behavior. We believe that such an index could be useful in detecting system 'flips' associated with a regime change, i.e. determining when systems are in a transient between one steady state and another. We illustrate the concepts using model ecosystems.     

Competence to make decisions: the psychology of deliberate decision making

This paper examines the psychological structure of mental competence, conceived of as competence in deliberate decision making. Analysis of that structure may be useful in understanding mental incompetence, as it occurs among some elderly persons. Mental competence not only depends on a number of cognitive abilities, such as foreseeing consequences, but also on the intactness of emotions, insight in one's own emotions, and abilities for emotion regulation.     

The ecological significance of toxic nectar

Although plant-herbivore and plant-pollinator interactions have traditionally been studied separately, many traits are simultaneously under selection by both herbivores and pollinators. For example, secondary compounds commonly associated with herbivore defense have been found in the nectar of many plant species, and many plants produce nectar that is toxic or repellent to some floral visitors. Although secondary compounds in nectar and toxic nectar are geographically and phylogenetically widespread, their ecological significance is poorly understood. Several hypotheses have been proposed for the possible functions of toxic nectar, including encouraging specialist pollinators, deterring nectar robbers, preventing microbial degradation of nectar, and altering pollinator behavior. All of these hypotheses rest on the assumption that the benefits of toxic nectar must outweigh possible costs; however, to date no study has demonstrated that toxic nectar provides fitness benefits for any plant. Therefore, in addition to these adaptive hypotheses, we should also consider the hypothesis that toxic nectar provides no benefits or is tolerably detrimental to plants, and occurs due to previous selection pressures or pleiotropic constraints. For example, secondary compounds may be transported into nectar as a consequence of their presence in phloem, rather than due to direct selection for toxic nectar. Experimental approaches are necessary to understand the role of toxic nectar in plant-animal interactions.     

The diversity and ecological significance of Protozoa

The unicellular eukaryotes are currently grouped in the kingdom Protista, together with their multicellular relatives. The inclusion of protozoa, algae and water moulds in a single taxon has resulted in nomenclatural problems, academic homelessness, and a reduction in their teaching. There are around 40 000 described protozoan protist species. Protozoa are principally grazers of bacteria, increasing mineralization and making nutrients more available to other organisms; most are aquatic, but they are also widespread animal parasites and symbionts. Their biomass, role in food chains, roles as mutualists and pathogens, and value as biomonitors are reviewed. To assess the role of protozoa in ecosystems more accurately, the current poor taxonomic standards in ecological work on protozoa must be improved. The manpower to respond to existing and new challenges in the field is declining as protozoology disappears from university courses and this problem needs to be addressed.     

The significance of clinical assessment of brain tissue oxygenation in different pathological conditions: an overview.

The development of methods of measurement of brain oxygenation in man is reviewed and the possible clinical potential of some new and established laboratory techniques is evaluated. Advantages and problems associated with the various approaches are considered together with the difficulties that are encountered in interpretation of data obtained and the factors that may increase such difficulties. It is concluded that invasive techniques that can only be used intraoperatively are of limited value but may be helpful in confirming the edges of ischemic areas or the restoration of adequate local blood flow. Chronically implanted devices have been useful in detecting epileptic foci and in evaluation of anesthetic regimes in patients with brain lesions. Infrared spectroscopy may offer possibilities for noninvasive whole brain monitoring in patients, but the method lacks resolution.     

The mouse genome: an overview.

A genetic map with one molecularly marked locus per cM will be available for the mouse in the near future. A map of this density should provide molecular reference points that connect genetic and physical maps, identify sites to initiate positional cloning studies for the molecular characterization of mutant loci, and define homologous regions of mouse and human genomes.