Do we know enough about controlling sediment to mitigate damage to stream ecosystems?

Stream and river ecosystems have suffered extensive degradation, and billions are expended annually on restoration efforts. However, few of these projects are monitored, and restoration effectiveness is often unknown. Consequently, there is a poor scientific foundation for restoration designs. Since many stream restoration efforts are at least partially targeted at controlling erosion of channel banks and beds, the effects of a large-scale, long-term stream erosion control effort in six Mississippi watersheds was assessed using 10–16 years of suspended sediment and water discharge records. Flow-adjusted suspended sediment concentrations showed no trends in five of the watersheds and a slight downward trend in one watershed, which was treated with small reservoirs as well as bed and bank erosion protection. Results indicate the inability of orthodox stream management structures (weirs and bank protection) to reduce watershed sediment yield and the need for a stronger scientific basis for stream restoration.     

What do we need to know about speciation?

Speciation has been a major focus of evolutionary biology research in recent years, with many important advances. However, some of the traditional organising principles of the subject area no longer provide a satisfactory framework, such as the classification of speciation mechanisms by geographical context into allopatric, parapatric and sympatry classes. Therefore, we have asked where speciation research should be directed in the coming years. Here, we present a distillation of questions about the mechanisms of speciation, the genetic basis of speciation and the relationship between speciation and diversity. Our list of topics is not exhaustive; rather we aim to promote discussion on research priorities and on the common themes that underlie disparate speciation processes.     

Consequences of habitat fragmentation for plant species: Do we know enough?

Habitat fragmentation is one of the most important causes for the decline of plant species. However, plants differing in phylogeny, habitat requirements and biology are likely to respond differently to habitat fragmentation. We ask whether case studies on the effects of habitat fragmentation conducted so far allow generalizations about its effects on the fitness and genetic diversity of populations of endangered plant species. We compared the characteristics of plant species endangered in Germany whose sensitivity to habitat fragmentation had been studied with those of the endangered species that had not been studied. We found strong discrepancies between the two groups with regard to their taxonomy and traits relevant to their sensitivity to habitat fragmentation. Monocots, graminoids, clonal, abiotically pollinated and self compatible species were underrepresented among the studied species, and most study species were from a few habitat types, in particular grasslands. We conclude that our current knowledge of the effects of habitat fragmentation on plant populations is not sufficient to provide widely applicable guidelines for species management. The selection of species studied so far has been biased toward species from certain habitats and species exhibiting traits that probably make them vulnerable to habitat fragmentation. Future studies should include community-wide approaches in different habitats, e.g. re-visitation studies in which the species pool is assessed at different time intervals, and population-biological studies of species from a wide range of habitats, and of different life forms and growth strategies. A more representative picture of the effects of habitat fragmentation would allow a better assessment of threats and more specific recommendations for optimally managing populations of endangered plants.     

What do we know about salt stress in bryophytes?

Bryophytes are among the first plants that faced the terrestrial way of life. They settled almost all terrestrial habitats, but no extant seawater representatives are known. It is not widely documented how bryophytes cope with salt stress, but there are species inhabiting salty environments. Here, we present the current state of knowledge on salt stress biology in bryophytes.     

What do we know about serotonin?

The present review focuses on what is known of basic serotonin physiology in the human body. Here, we describe serotonin biochemistry and metabolism and summarize the results of studies that have contributed significantly to our understanding of serotonin physiology. We report the well-established role of serotonin in cardiovascular, gastrointestinal, and circulatory physiology. Emphasis is placed on the role of serotonin in peripheral physiological systems rather than in the central nervous system. A brief overview is provided on the emerging role of serotonin in novel areas such as bone pathways and glucose uptake. We also report a select few animal studies and animal models that have provided worthwhile contributions to the understanding of serotonin in human physiology. In addition, we summarize the results of large-scale genetic studies on serotonin and serotonin transporter genes, performed in relation to behavioral and mood disorders.     

What do we know about mechanical strain in lung alveoli?

The pulmonary alveolus, terminal gas-exchange unit of the lung, is composed of alveolar epithelial and endothelial cells separated by a thin basement membrane and interstitial space. These cells participate in the maintenance of a delicate system regulated not only by biological factors but also by the mechanical environment of the lung, which undergoes dynamic deformation during breathing. Clinical and animal studies as well as cell culture studies point toward a strong influence of mechanical forces on lung cells and tissues including effects on growth and repair, surfactant release, injury, and inflammation. However, despite substantial advances in our understanding of lung mechanics over the last half century, there are still many unanswered questions regarding the micromechanics of the alveolus and how it deforms during lung inflation. Therefore, the aims of this review are to draw a multidisciplinary account of the mechanics of the alveolus on the basis of its structure, biology, and chemistry and to compare estimates of alveolar deformation from previous studies.     

Why do we need to know more about mixed Plasmodium species infections in humans?

Four Plasmodium species cause malaria in humans. Most malaria-endemic regions feature mixed infections involving two or more of these species. Factors contributing to heterogeneous parasite species and disease distribution include differences in genetic polymorphisms underlying parasite drug resistance and host susceptibility, mosquito vector ecology and transmission seasonality. It is suggested that unknown factors limit mixed Plasmodium species infections, and that mixed-species infections protect against severe Plasmodium falciparum malaria. Careful examination of methods used to detect these parasites and interpretation of individual- and population-based data are necessary to understand the influence of mixed Plasmodium species infections on malarial disease. This should ensure that deployment of future antimalarial vaccines and drugs will be conducted in a safe and timely manner.     

Managing fire‐dependent vegetation in Byron Shire,Australia: Are we restoring the keystone ecological process of fire?

Fire is a keystone ecological process in many ecosystems. In such ecosystems, the exclusion of fire can lead to fundamental shifts in vegetation structure, composition and distribution and poses a major threat to the biodiversity dependent on these habitats. Programmes to manage and restore native vegetation have increased rapidly over recent decades, and while many such programmes have demonstrable success managing a range of environmental threats, their effectiveness in identifying and addressing the major threat of fire exclusion in fire‐dependent vegetation is questionable. This study sought to identify impediments to the management of fire‐excluded vegetation at the assessment and planning stage of ecological management programmes in Byron Shire in north‐east New South Wales. Sixty ecological management and restoration plans for sites known to be fire‐excluded in the shire were reviewed to determine the rate at which fire exclusion was identified and addressed in planning over the last decade. Document analysis found the majority of plans failed to accurately identify fire exclusion or to recommend the reintroduction of fire in fire‐excluded management sites. Absence of standardised guidelines that require comprehensive consideration of fire exclusion in ecological management and restoration plans is suggested as a key factor in the low response rates observed. Furthermore, it was found that existing implicit prompts to address inappropriate‐fire regimes generally, including government policies, project objectives and site‐assessment prompts had little effect on identification and response rates, further confirming the need for more‐explicit assessment prompts relating to fire‐frequency issues. Without improvements of the current ecological assessment and planning process to increase identification and management of fire exclusion in the study area, fire‐dependent biodiversity values will continue to decline wherever fire exclusion remains unmanaged. It is recommended that explicit assessment and planning templates are developed and implemented to effectively manage fire exclusion and conserve the fire‐dependent biodiversity of Byron Shire and the far north coast of NSW.     

Spatial dynamics in model plant communities: what do we really know?

A variety of models have shown that spatial dynamics and small-scale endogenous heterogeneity (e.g., forest gaps or local resource depletion zones) can change the rate and outcome of competition in communities of plants or other sessile organisms. However, the theory appears complicated and hard to connect to real systems. We synthesize results from three different kinds of models: interacting particle systems, moment equations for spatial point processes, and metapopulation or patch models. Studies using all three frameworks agree that spatial dynamics need not enhance coexistence nor slow down dynamics; their effects depend on the underlying competitive interactions in the community. When similar species would coexist in a nonspatial habitat, endogenous spatial structure inhibits coexistence and slows dynamics. When a dominant species disperses poorly and the weaker species has higher fecundity or better dispersal, competition-colonization trade-offs enhance coexistence. Even when species have equal dispersal and per-generation fecundity, spatial successional niches where the weaker and faster-growing species can rapidly exploit ephemeral local resources can enhance coexistence. When interspecific competition is strong, spatial dynamics reduce founder control at large scales and short dispersal becomes advantageous. We describe a series of empirical tests to detect and distinguish among the suggested scenarios.     

Why do we need permanent plots in the study of long-term vegetation dynamics?

Abstract. This paper presents a survey of vegetation studies on permanent plots, with an emphasis on the long-term character of these studies. It makes remarks on the external and internal causes of succession, pays attention to the pathways of succession, links up permanent plots studies and chronosequences, discusses internal causes and mechanisms of succession, and finally mentions the significance of long-term vegetation dynamics for nature conservation.     

What do we know about IL-6 in COVID-19 so far?

Interleukin 6(IL-6)is a cytokine with dual functions of pro-inflammation and anti-inflammation.It is mainly produced by mononuclear macrophages,Th2 cells,vascul...     

From monkeys to humans: what do we now know about brain homologies?

Different primate species, including humans, have evolved by a repeated branching of lineages, some of which have become extinct. The problem of determining the relationships among cortical areas within the brains of the surviving branches (e.g. humans, macaque monkeys, owl monkeys) is difficult for several reasons. First, evolutionary intermediates are missing, second, measurement techniques are different in different primate species, third, species differ in body size, and fourth, brain areas can duplicate, fuse, or reorganize between and within lineages.     

Managing ecosystem services: what do we need to know about their ecology?

Human domination of the biosphere has greatly altered ecosystems, often overwhelming their capacity to provide ecosystem services critical to our survival. Yet ecological understanding of ecosystem services is quite limited. Previous work maps the supply and demand for services, assesses threats to them, and estimates economic values, but does not measure the underlying role of biodiversity in providing services. In contrast, experimental studies of biodiversity-function examine communities whose structures often differ markedly from those providing services in real landscapes. A bridge is needed between these two approaches. To develop this research agenda, I discuss critical questions and key approaches in four areas: (1) identifying the important 'ecosystem service providers'; (2) determining the various aspects of community structure that influence function in real landscapes, especially compensatory community responses that stabilize function, or non-random extinction sequences that rapidly erode it; (3) assessing key environmental factors influencing provision of services, and (4) measuring the spatio-temporal scale over which providers and services operate. I show how this research agenda can assist in developing environmental policy and natural resource management plans.