Coping with multiple enemies: an integration of molecular and ecological perspectives

How plants respond to attack by the range of herbivores and pathogens that confront them in the field is the subject of considerable research by both molecular biologists and ecologists. However, in spite of the shared focus of these two bodies of research, there has been little integration between them. We consider the scope for such integration, and how greater dialogue between molecular biologists and ecologists could advance understanding of plant responses to multiple enemies.     

Cooperation: integrating evolutionary and ecological perspectives

Putting a competitive squeeze on a cooperative group has long been considered to encourage cheats. Now we learn that competition, by driving diversification among cooperators, can create groups that are both more productive and more resistant to defection.     

Bacteriocin diversity: ecological and evolutionary perspectives

The bacteriocin family is the most abundant and diverse group of bacterial defense systems. Bacteriocins range from the well-studied narrow spectrum, high molecular weight colicins produced by Escherichia coli and the short polypeptide lantibiotics of lactic acid bacteria to the relatively unknown halocins produced almost universally by the haolobacteria. The abundance and diversity of this potent arsenal of weapons is clear. Less clear is their evolutionary origins and the role they play in mediating microbial interactions. The goal of this review is to explore what we know about the evolution and ecology of the best-characterized family of bacteriocins, the colicins. We summarize current knowledge of how such extraordinary protein diversity arose and is maintained in microbial populations and what role these toxins play in mediating microbial population-level and community-level dynamics.     

Species borders: ecological and evolutionary perspectives

Recent ecological studies on species borders have used a number of approaches to establish causation for specific environmental factors and to identify the traits involved. These include interspecific comparisons, detailed investigations of marginal populations, and experimental manipulation. Species borders continue to be largely ignored in evolutionary biology, although some work suggests that marginal populations may often be relatively better-adapted to unfavourable conditions but perform poorly under most other conditions.     

Coral reef bleaching: ecological perspectives

Coral reef bleaching, the whitening of diverse invertebrate taxa, results from the loss of symbiotic zooxanthellae and/or a reduction in photosynthetic pigment concentrations in zooxanthellae residing within the gastrodermal tissues of host animals. Of particular concern are the consequences of bleaching of large numbers of reef-building scleractinian corals and hydrocorals. Published records of coral reef bleaching events from 1870 to the present suggest that the frequency (60 major events from 1979 to 1990), scale (co-occurrence in many coral reef regions and often over the bathymetric depth range of corals) and severity (>95% mortality in some areas) of recent bleaching disturbances are unprecedented in the scientific literature. The causes of small scale, isolated bleaching events can often be explained by particular stressors (e.g., temperature, salinity, light, sedimentation, aerial exposure and pollutants), but attempts to explain large scale bleaching events in terms of possible global change (e.g., greenhouse warming, increased UV radiation flux, deteriorating ecosystem health, or some combination of the above) have not been convincing. Attempts to relate the severity and extent of large scale coral reef bleaching events to particular causes have been hampered by a lack of (a) standardized methods to assess bleaching and (b) continuous, long-term data bases of environmental conditions over the periods of interest. An effort must be made to understand the impact of bleaching on the remainder of the reef community and the long-term effects on competition, predation, symbioses, bioerosion and substrate condition, all factors that can influence coral recruitment and reef recovery. If projected rates of sea warming are realized by mid to late AD 2000, i.e. a 2°C increase in high latitude coral seas, the upper thermal tolerance limits of many reef-building corals could be exceeded. Present evidence suggests that many corals would be unable to adapt physiologically or genetically to such marked and rapid temperature increases.     

Evolution of plant resistance at the molecular level: ecological context of species interactions

Molecular data regarding the diversity of plant loci involved in resistance to herbivores or pathogens are becoming increasingly available. These genes demonstrate variable patterns of diversity, suggesting that they differ in their evolutionary history. In parallel, the study of natural variation for resistance, generally conducted at the phenotypic level, has shown that resistance does not evolve solely under selection pressures exerted by enemies. Metapopulation dynamics and other ecological characteristics of interacting species also appear to have a large impact on resistance evolution. Until now, studies of resistance at the molecular level have been conducted separately from ecological studies in extant populations. Future progress requires an evolutionary approach integrating both molecular and ecological aspects of resistance evolution. Such an approach will contribute greatly to our understanding of the evolution of molecular diversity at loci involved in biotic stress.     

Theoretical molecular biology: prospectives and perspectives

I briefly discuss some aspects of theoretical molecular biology. Specifically, I include the issues of searches for homologies via string matchings, for patterns of specific nucleotide groupings and of sequence-structure relationship. The various approaches developed in order to achieve this end are described, attempting to convey some of the excitement in this quickly growing field.     

Neotropical bromeliads as food sources for birds: a systematic review and perspectives on the management of ecological interactions

The loss of interactions and ecosystem functions is a concerning by-product of pervasive Anthropocene species decline and extinction. Ecological interactions between species sustain the provision of ecosystem processes, especially those mediated by trophic relationships such as pollination and predation. At the local habitat scale, the diversity of natural food sources may increase the diversity of interactions, thus enhancing the stability of local communities and ecosystem functioning. Here I discuss the importance of bromeliads as a potential provider of additional trophic interactions with birds, a key animal group in the Neotropics. Based on 88 studies published between 1965 and 2020 across the Neotropical region, I observed that bromeliads act as ‘wildlife restaurants’ by providing an additional food source throughout the year in almost all Neotropical ecosystems for at least 162 bird species (mostly hummingbirds). These plants (both epiphytic and terrestrial forms) can provide nectar, flowers, water for drinking, invertebrates, small vertebrates, seeds, and fruits, as well as nest materials and substrates. Given these trophic relationships between bromeliads and birds, actions to restore the richness and abundance of these plants in changed habitats would potentially enhance the local diversity of birds. I discuss and recommend the use of bromeliad transplantations as a relevant conservation tool for birds and some implications for the maintenance of species and interaction diversity in natural and agricultural habitats.     

Clonal architecture in marine macroalgae: ecological and evolutionary perspectives

The study of the ecological and evolutionary consequences of clonal growth in vascular plants has been widely addressed; however, marine macroalgae, which are interesting modular organisms that combine simple morphologies and complex life cycles, have been almost ignored. This paper presents a review and analysis of the ecological and evolutionary consequences of clonality in marine macroalgae, including three main subjects: (1) modular construction (modules and ramets); (2) life cycle and evolutionary perspectives, and (3) ecological perspectives of clonality in marine macroalge. The biological emergent attributes of clonality are present in marine macroalgae e.g. high longevity of the genet by the continual renewal of modules, and variable morphological plasticity of ramets and modules in relation to environmental conditions. However, experimental work is still needed to solve questions such as the effect of crowding on survival rates and use of resources, as well as its effect on sexual or asexual patterns of reproduction. I expect that the study of the evolutionary consequences of the combined presence of alternation of generations and clonal growth in marine macroalgae will make important contributions to clonal plant theory.     

Tumour-stroma interactions in carcinogenesis: basic aspects and perspectives

In contrast to the conventional notion regarding tumour development as a cell autonomous process in which the major participants were the cancer cells, increasing evidence attributes important role in the stromal components, namely fibroblasts, and view the tumour as a heterogenous mixture of different cell types. These different types of cells, being cancer cells, fibroblasts, endothelial cells, and others, interact reciprocally and play an almost equally important role in the manifestation of certain aspects of the malignant phenotype. The elucidation of the mechanistic base of such interactions, besides the contribution to understand fundamental aspects of tumour cell biology, promises important applications in diagnosis, prognosis and therapy of the disease.     

Congenital adrenal hyperplasia: biochemical and molecular perspectives

Congenital adrenal hyperplasia is a disorder occurring in both sexes and is the commonest cause of ambiguous genitalia. It is a group of autosomal recessive disorders in which, on the basis of an enzyme defect the bulk of steroid hormone production by adrenal cortex shifts from corticosteroids to androgens. Autosomal recessive mutations in the CYP21, CYP17, CYP11B1 and 3betaHSD genes that encode steroidogenic enzymes, in addition to mutations in the gene encoding the intracellular cholesterol transport protein steroidogenic acute regulatory protein StAR can cause CAH. Each of the defects causes different biochemical consequences and clinical features. Deficiencies in 21 hydroxylase (21-OH) and 11beta-Hydroxylase (11beta-OH) are the two most frequent causes of CAH. All the biochemical defects impair cortisol secretion, resulting into compensatory hypersecretion of ACTH and consequent hyperplasia of the adrenal cortex. Research in recent years has clarified clinical, biochemical and genetic problems in diagnosis and treatment of the disorders. Expanding knowledge of the gene mutations associated with each of these disorders is providing valuable diagnostic tools in addition to the biochemical profile and phenotype. Genotyping is useful in selecting instances to provide genetic counseling and to clarify ambiguous cases.     

Measles virus and immunomodulation: molecular bases and perspectives

Measles virus (MV) remains among the most potent global pathogens, killing more than 1 million children annually. The virus induces a profound suppression of immune functions that favours the establishment of, and aggravates the course of, secondary infections. By contrast, MV-specific immune responses are efficiently generated, and these clear the virus from the organism and confer a long-lasting immunity. As sensitisers of pathogen encounter and instructors of the adaptive immune response, professional antigen-presenting cells (APCs) such as dendritic cells play a decisive role in the induction and quality of the MV-specific immune response. However, key features of immune suppression associated with MV are compatible with interference with APC maturation and function, and subsequent qualitative and quantitative alterations of T-cell activation.     

Biological soil crusts in ecological restoration: emerging research and perspectives

Drylands encompass over 40% of terrestrial ecosystems and face significant anthropogenic degradation causing a loss of ecosystem integrity, services, and deterioration of social‐ecological systems. To combat this degradation, some dryland restoration efforts have focused on the use of biological soil crusts (biocrusts): complex communities of cyanobacteria, algae, lichens, bryophytes, and other organisms living in association with the top millimeters of soil. Biocrusts are common in many ecosystems and especially drylands. They perform a suite of ecosystem functions: stabilizing soil surfaces to prevent erosion, contributing carbon through photosynthesis, fixing nitrogen, and mediating the hydrological cycle in drylands. Biocrusts have emerged as a potential tool in restoration; developing methods to implement effective biocrust restoration has the potential to return many ecosystem functions and services. Although culture‐based approaches have allowed researchers to learn about the biology, physiology, and cultivation of biocrusts, transferring this knowledge to field implementation has been more challenging. A large amount of research has amassed to improve our understanding of biocrust restoration, leaving us at an opportune time to learn from one another and to join approaches for maximum efficacy. The articles in this special issue improve the state of our current knowledge in biocrust restoration, highlighting efforts to effectively restore biocrusts through a variety of different ecosystems, across scales and utilizing a variety of lab and field methods. This collective work provides a useful resource for the scientific community as well as land managers.     

The community context of species' borders: ecological and evolutionary perspectives

Species distributional limits may coincide with hard dispersal barriers or physiological thresholds along environmental gradients, but they may also be influenced by species interactions. We explore a number of models of interspecific interactions that lead to (sometimes abrupt) distribution limits in the presence and absence of environmental gradients. We find that gradients in competitive ability can lead to spatial segregation of competitors into distinct ranges, but that spatial movement tends to broaden the region of sympatry between the two species, and that Allee effects tend to sharpen these boundaries. We generalize these simple models to include metapopulation dynamics and other types of interactions including predator–prey and host–parasite interactions. We derive conditions for range limits in each case. We also consider models that include coevolution and gene flow and find that character displacement along environmental gradients can lead to stable parapatric distributions. We conclude that it is essential to consider coevolved species interactions as a potential mechanism limiting species distributions, particularly when barriers to dispersal are weak and environmental gradients are gradual.     

The eutrophic Loosdrecht Lakes: Current ecological research and restoration perspectives

Features of the Loodsrecht Lakes, with emphasis on the main lake, are discussed with reference to restoration.Characteristics of the present situation are: (1) very low water transparency-Secchi-disc readings around 0.3 m occur in all seasons; (2) relatively small seasonal changes in sestonic matter; (3) important input of resuspended particles into the seston; (4) predominance of filamentous blue-green algae for most of the year; (5) relative scarcity of crustacean zooplankton, while rotifers are abundant; (6) poor development of littoral communities, and absence of benthic producers. The blue-green algae maintain high population density at very low growth rates: rates of loss are low. The zooplankton grazing rate is low due to inefficient filtering, but predation of larger crustaceans by fish may also be important. Studies on epipelon indicated that loss by deposition may be largely compensated by resuspension.Starting in 1984, the external phosphorus loading was markedly reduced. Results for 1984 and 1985 indicate that complementary measures are needed in order to improve water quality. Action should be directed towards increasing the phytoplankton turnover rates. Accelerated specific growth rate can be expected to accompany lower biomass, more successful competition by other algal groups, and enhancement of grazing pressure.Considering the shallowness of the system, promotion of littoral development and return of submerged vegetation may be important in establishing a new equilibrium of the system.     

建立我国生态补偿机制的思路与措施

建立生态补偿机制是促进我国生态保护、协调区域发展一项重要制度设计.尽管我国在国家、区域、流域等尺度上的生态补偿实践取得了很大进展,但仍存在缺乏系统的制度设计、政府单方面决策为主与利益相关参与不够、补偿范围界定方法不科学、生态补偿对象和补偿方式不完善;补偿标准低与确定方法缺乏科学基础;缺乏监督机制和政策效果不明显等方面不足.围绕统筹人与自然和谐发展的制度建设,提出了建立适合我国国情生态补偿机制的原则,并从以下方面探讨了建立生态补偿机制的措施与对策:科学确定生态补偿地域范围;明确生态补偿载体与补偿对象;建立合理的生态补偿经济标准核算方法;建立和完善生态环境补偿机制的措施,以期为建立协调人与自然和谐发展的制度提供参考.