How to account for habitat suitability in weed management programmes?

Designing efficient management strategies for already established invasive alien species is challenging. Here, we ask whether environmental suitability, as predicted by species distribution models, is a useful basis of cost-effective spatial prioritization in large-scale surveillance and eradication programmes. We do so by means of spatially and temporarily explicit simulations of the spread of a case study species (Ambrosia artemisiifolia L.) in Austria and southern Germany under different management regimes. We ran these simulations on a contiguous grid of the study area with each grid cell (~35 km²) characterized by a habitat suitability value derived from the predictions of a species distribution model. The management regimes differed in terms of (a) a minimum habitat suitability rank p (suitability threshold) used to separate cells for surveillance from those which are not controlled; and (b) the strategy for selecting cells for annual campaigns from the pool defined by p. According to the results (i.e., number of cells infested in 2050 as well as infested on average per year) the most efficient way to base surveillance on suitability is to define the temporal sequence of management according to the grid cells’ suitability ranks. Management success declines sharply when the suitability threshold is set too high, but only moderately when it is set too low. We conclude that accounting for environmental suitability is important for large-scale management programmes of invasive alien species and that species distribution models are hence useful tools for designing such programmes.     

How to increase juvenile shrimps in mangrove waters?

The distribution, density and species composition of juvenile shrimps were studied in three mangrove zones of Pichavaram, situated on the southeast coast of India. Nine species of shrimps dominated with Metapenaeus monoceros, M. brevicornis and Penaeus indicus were recorded. This shrimp resource was higher in mangrove-lined waters than that in neritic waters. This field observation was experimentally proved using litter bags. The average catch around the litter bags was 0.80 individuals day^–1 for Rhizophora leaves, 1.6 ind. day^–1 for Avicennia leaves and 0.16 ind. day^–1 in control. In general, abundance of juvenile shrimps was the highest around the leaves that were decomposed for 40 days and colonized with high counts of nitrogen-fixing azotobacters. Finally, a vegetation trap technique using mangrove leaves has been proposed for efficient schooling of juvenile shrimps. There was about 3-fold increase in number of shrimp juveniles around the trap than at control waters.     

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.     

How much do we know about the current extinction rate?

Since about J600, 486 animal species have been recorded extinct. This represents about 0.04% of all animal species so far described. In the same period, 600 plant species are known to have disappeared, about 0.25% of the total. These figures are much smaller than those of the Permian/ Triassic and Cretaceous/Tertiary mass extinctions. One might therefore conclude that at present life on earth is at comparatively little risk of extinction. However, there is a growing body of data to show that the converse is true.     

How to value biodiversity in environmental management?

Biodiversity is globally recognised as a cornerstone of healthy ecosystems, and biodiversity conservation is increasingly becoming one of the important aims of environmental management. Evaluating the trade-offs of alternative management strategies requires quantitative estimates of the costs and benefits of their outcomes, including the value of biodiversity lost or preserved. This paper takes a decision-analytic standpoint, and reviews and discusses the alternative aspects of biodiversity valuation by dividing them into three categories: socio-cultural, economic, and ecological indicator approaches. We discuss the interplay between these three perspectives and suggest integrating them into an ecosystem-based management (EBM) framework, which permits us to acknowledge ecological systems as a rich mixture of interactive elements along with their social and economic aspects. In this holistic framework, socio-cultural preferences can serve as a tool to identify the ecosystem services most relevant to society, whereas monetary valuation offers more globally comparative and understandable values. Biodiversity indicators provide clear quantitative measures and information about the role of biodiversity in the functioning and health of ecosystems. In the multi-objective EBM approach proposed in the paper, biodiversity indicators serve to define threshold values (i.e., the minimum level required to maintain a healthy environment). An appropriate set of decision-making criteria and the best method for conducting the decision analysis depend on the context and the management problem in question. Therefore, we propose a sequence of steps to follow when quantitatively evaluating environmental management against biodiversity.     

Molecular systems biology at the crossroads: to know less about more,or to know more about less?

Systems biology is a rapidly evolving discipline that endeavours to understand the detailed coordinated workings of entire organisms, with the ultimate goal to detect differences between health and disease, or to understand how cells or entire organisms react to the environment. The editorial provides a critical evaluation of what molecular systems analysis can and cannot accomplish with existing methodologies, and how systems biology needs to merge with reductionism to yield a more comprehensive and mechanistically insightful model of a cell or organism.     

Do trout respond to riparian change? A meta‐analysis with implications for restoration and management

相似文献   

To know or not to know? Practices of knowledge and ignorance among Bidayuhs in an 'impurely' Christian world

This article seeks to render ignorance analytically and ethnographically productive by exploring practices and tropes of knowing and not-knowing among young Christian Bidayuhs in Sarawak, Malaysian Borneo. It argues that these Bidayuhs' professed ignorance of the old 'religion', adat gawai , cannot be dismissed as a simple lack of knowledge or reflection of sheer indifference. Instead, their invocations of ignorance could be understood as a productive, empowering device for dealing with the dangers of living in a world in which religious conversion remains an ongoing, incomplete process. Through this ethnographic analysis, the article also offers a reflexive critique of the knowledge-centred impulses that often shape anthropology's epistemological and methodological projects.  

Résumé

L'auteure cherche à rendre l'ignorance féconde du point de vue anecdotique et ethnographique en explorant les pratiques et figures rhétoriques liées à la connaissance et à l'ignorance chez les jeunes Bidayuhs chrétiens du Sarawak, dans la partie malaise de Bornéo. Elle affirme que l'ignorance de « l'ancienne religion >>, adat gawai , professée par ces Bidayuhs ne peut pas être réduite à un manque de connaissance ou à l'expression d'une simple indifférence. Elle pourrait, au contraire, constituer un dispositif productif et efficace permettant de gérer les dangers d'un monde dans lequel la conversion religieuse reste un processus permanent et incomplet. Par cette étude ethnographique, l'article offre aussi une critique des impulsions centrées sur le savoir qui donnent souvent forme aux projets épistémologiques et méthodologiques de l'anthropologie.     

How much can we know about the causes of evolutionary trends?

One of the first questions that paleontologists ask when they identify a large-scale trend in the fossil record (e.g., size increase, complexity increase) is whether it is passive or driven. In this article, I explore two questions about driven trends: (1) what is the underlying cause or source of the directional bias? and (2) has the strength of the directional bias changed over time? I identify two underdetermination problems that prevent scientists from giving complete answers to these two questions.     

What do we know about Hawaiian ferns and lycophytes?

The Hawaiian Islands are home to one of the most distinctive fern and lycophyte floras in the world. Of the 144 native fern species, 76% are endemic and, including subspecies and varieties, 84% of the 167 native fern taxa are endemic. There are 15 native lycophyte species, 47% of which are endemic, and 16 taxa, 50% of which are endemic. I review here most of the available literature on Hawaiian ferns and lycophytes. Few species of ferns or lycophytes have been studied in any kind of detail and, for most, we only know basic classification and general ecological information. Although the total number of studies reviewed here is not large, research has been conducted on a wide range of topics including systematics, floristics, dispersal, phylogeny, biogeography, ecology, form and function, population genetics, microevolution, fern-animal and fern-fungi associations, reproductive biology, demography, ethnobotany, and conservation.     

Cancer and diet: How are they related?

Extensive research in the past decade has revealed cancer to be a multigenic disease caused by perturbation of multiple cell signalling pathways and dysregulation of numerous gene products, all of which have been linked to inflammation. It is also becoming evident that various lifestyle factors, such as tobacco and alcohol use, diet, environmental pollution, radiation and infections, can cause chronic inflammation and lead to tumourigenesis. Chronic diseases caused by ongoing inflammation therefore require chronic, not acute, treatment. Nutraceuticals, compounds derived from fruits, vegetables, spices and cereals, can be used chronically. This study discusses the molecular targets of some nutraceuticals that happen to be markers of chronic inflammation and how they can prevent or treat cancer. These naturally-occurring agents in the diet have great potential as anti-cancer drugs, thus proving Hippocrates, who proclaimed 25 centuries ago, 'Let food be thy medicine and medicine be thy food'.     

How is diversity related to species turnover through time?

Empirical studies across a wide range of taxa show that the slopes of species–time relationships often decline as average species richness increases, indicating that more diverse communities have greater temporal stability in species composition. I explored potential explanations for this observation using two simple model formulations for species temporal dynamics. In the Abiotic model, species turnover is governed by the degree of heterogeneity in the environment and the range of species' tolerances. In this case, more variable conditions lead to lower species richness and higher turnover, but only if the distribution of species' niche widths and the size of the species pool are independent of the degree of environmental variability. The Biotic model represents direct effects of diversity on turnover through positive or negative feedbacks between diversity and species' colonization and extinction rates. Declining turnover with increasing richness occurred when higher diversity either facilitated colonization by new species or reduced extinction rates of extant species. Both models could produce the observed pattern of declining turnover at higher diversity under some circumstances, however the conditions for this outcome in the Abiotic model were restrictive and potentially unrealistic. The models provide a process-based framework for understanding the connection between diversity and species turnover through time.     

Application of traditional ecological knowledge in the management and sustainability of fisheries in East Africa: a long-neglected strategy?

Management and sustainability of fisheries has been guided by theories and models derived from modern ecological science. Traditional ecological knowledge (TEK) has been ignored in all spheres of decision-making for management and sustainability of fisheries in East Africa. TEK guided African communities in the way they associated and interacted with the natural environment around them. Spiritual rituals, religious practices, social taboos and sacred animal totems guided the peoples on how and when to utilize the available natural resources. In the advent of modern scientific knowledge, the African traditional knowledge quickly faded away and is generally seen as irrelevant. Today the potential of TEK in the management and sustainability of fisheries in East Africa has not been realized and its status and future is unknown. TEK should be complementary to modern scientific knowledge in the management and sustainability of fisheries. This paper therefore focuses on the potential application of TEK in the management and sustainability of fisheries in East Africa and the issues that impede its application.     

How are humans related to other primates? A guided inquiry laboratory for undergraduate students

Understanding that phylogenies depict the evolutionary history of species is a critical concept for undergraduate biology students. We present an inquiry-based laboratory exercise exploring this concept in the context of the human phylogeny. This activity reinforces several important biological concepts and skills. Bolstered concepts include that evolution is descent with modification, that evolution is a genetic process, and that humans are closely related to apes. In terms of thinking skills, the lab gives students practice with hypothetical-deductive thinking, quantifying patterns from complex data, and evaluating evidence.     

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.