An academic biography of Colonel David de Crespigny Smiley and his intimate involvement in clandestine operations of the British secret service. Draws on extensive interviews and archival research, ...including 20 hours of interview conducted with Colonel David Smiley himself . Uncovers the motivations and ideals that informed Smiley’s commitment to covert action and intelligence during the Second World War and early part of the Cold War, often among tribally based societies. Addresses the wider issues of accountability and control of clandestine operations, referring in particular to operations in Albania, Oman and Yemen.
Biogeomorphologists study the roles of biota in landscape formation and decay. Ecologists interested in ecosystem engineering study environmental change caused by biota and the consequences for the ...engineer, other organisms, and ecological processes. The interface is geomorphological change, an interface both are aware of but study somewhat independently and differently. Interaction and integration among the two fields is the goal of this special issue. Here I take an ecological perspective of geomorphological change caused by ecosystem engineers in patches within landscapes that I hope can help facilitate this goal. I ask the following general questions: When will an ecosystem engineering species create a geomorphological signature in a landscape? What, in qualitative terms, is such a signature? How can the signature be estimated and how long will it last? What engineer attributes and ecological factors will determine signature change? What creates complications? How do the answers inform whether or not life leaves a geomorphological signature? To attempt answers, I develop a provisional, general theory of ecosystem engineering signatures that draws on and integrates a geomorphological foundation of balance between formation and decay; landscape patch dynamics; a general framework for ecosystem engineering; and empirical studies. I treat a landscape engineering signature as the balance of rates of formation (F) and rates of decay (D) across patches whose ratio value (F/D) can be transformed (>1), intermediate (1) or untransformed (<1). I suggest amenable systems for study. I describe how the signature can be estimated and evaluated for potential persistence, and how to identify when decay or engineer density and per capita engineering activity control the signature. I examine the influences on shifts from transformed to untransformed signatures, and vice versa, at constant and changing rates of decay. I show how the likelihood of signature shifts depends on: 1. engineer density in the landscape and per patch; 2. per capita engineering activity as structure per patch and patches per engineer, or its contribution for engineers occurring in groups; 3. the degree of patch maintenance, abandonment, and re-engineering of abandoned patches; and in some situations, 4. the direction of the signature shift that is considered. I use this to illustrate how different ecological factors affecting engineer species (e.g., abiotic resources and conditions, natural enemies) and engineer feedbacks can drive signature transitions. I address complications and how they might be dealt with for situations where an engineer species causes formation and decay; when multiple engineering species co-occur; and when patches are materially interconnected. I end by considering whether life leaves a geomorphological signature, using this to contrast my approach with biogeomorphology, and asking what a hypothetical analysis of signature patterns across many engineer species/landscape combinations might imply for the interface of ecology and biogeomorphology.
► I develop a theory of geomorphological signatures created by ecosystem engineers. ► Engineer formation rate/decay rate, across patches, defines a landscape signature. ► Engineer attributes and decay forces determine signature sensitivity to change. ► Three general engineer attributes determine signature sensitivity. ► The findings inform the degree to which life creates a geomorphological signature.
The modification of the physical environment by organisms is a critical interaction in most ecosystems. The concept of ecosystem engineering acknowledges this fact and allows ecologists to develop ...the conceptual tools for uncovering general patterns and building broadly applicable models. Although the concept has occasioned some controversy during its development, it is quickly gaining acceptance among ecologists. We outline the nature of some of these controversies and describe some of the major insights gained by viewing ecological systems through the lens of ecosystem engineering. We close by discussing areas of research where we believe the concept of organisms as ecosystem engineers will be most likely to lead to significant insights into the structure and function of ecological systems.
Boom‐bust dynamics – the rise of a population to outbreak levels, followed by a dramatic decline – have been associated with biological invasions and offered as a reason not to manage troublesome ...invaders. However, boom‐bust dynamics rarely have been critically defined, analyzed, or interpreted. Here, we define boom‐bust dynamics and provide specific suggestions for improving the application of the boom‐bust concept. Boom‐bust dynamics can arise from many causes, some closely associated with invasions, but others occurring across a wide range of ecological settings, especially when environmental conditions are changing rapidly. As a result, it is difficult to infer cause or predict future trajectories merely by observing the dynamic. We use tests with simulated data to show that a common metric for detecting and describing boom‐bust dynamics, decline from an observed peak to a subsequent trough, tends to severely overestimate the frequency and severity of busts, and should be used cautiously if at all. We review and test other metrics that are better suited to describe boom‐bust dynamics. Understanding the frequency and importance of boom‐bust dynamics requires empirical studies of large, representative, long‐term data sets that use clear definitions of boom‐bust, appropriate analytical methods, and careful interpretations.
Rates of biodiversity loss are higher in freshwater ecosystems than in most terrestrial or marine ecosystems, making freshwater conservation a priority. However, prioritization methods are impeded by ...insufficient knowledge on the distribution and conservation status of freshwater taxa, particularly invertebrates. We evaluated the extinction risk of the world's 590 freshwater crayfish species using the IUCN Categories and Criteria and found 32% of all species are threatened with extinction. The level of extinction risk differed between families, with proportionally more threatened species in the Parastacidae and Astacidae than in the Cambaridae. Four described species were Extinct and 21% were assessed as Data Deficient. There was geographical variation in the dominant threats affecting the main centres of crayfish diversity. The majority of threatened US and Mexican species face threats associated with urban development, pollution, damming and water management. Conversely, the majority of Australian threatened species are affected by climate change, harvesting, agriculture and invasive species. Only a small proportion of crayfish are found within the boundaries of protected areas, suggesting that alternative means of long-term protection will be required. Our study highlights many of the significant challenges yet to come for freshwater biodiversity unless conservation planning shifts from a reactive to proactive approach.
All living organisms modify their biotic and abiotic environment. Niche construction theory posits that organism-mediated modifications to the environment can change selection pressures and influence ...the evolutionary trajectories of natural populations. While there is broad support for this proposition in general, there is considerable uncertainty about how niche construction is related to other similar concepts in ecology and evolution. Comparative studies dealing with certain aspects of niche construction are increasingly common, but there is a troubling lack of experimental tests of the core concepts of niche construction theory. Here, we propose an operational framework to evaluate comparative and experimental evidence of the evolutionary consequences of niche construction, and suggest how such research can improve our understanding of ecological and evolutionary dynamics in ecosystems. We advocate for a shift toward explicit experimental tests of how organism-mediated environmental change can influence the selection pressures underlying evolutionary responses, as well as targeted field-based comparative research to identify the mode of evolution by niche construction and assess its importance in natural populations.
Britain’s hasty departure from Aden and South Arabia after 128 years has often been presented as a humiliation at best and a disaster at worst. London’s hopes of handing power and sovereignty over to ...a friendly federal regime collapsed in the face of a nationalist uprising backed that enjoyed the support of Egypt. Five decades after the final British troops left Aden, academic experts and former British officials directly involved in the events that unfolded critically reflect on British withdrawal from South Arabia, the post-colonial problems in South Yemen that still resonate today, and how the United Kingdom learnt from its experience in stabilising Oman while overseeing the formation of the United Arab Emirates.
Here we utilize a combination of genetic data, oceanographic data, and local ecological knowledge to assess connectivity patterns of the ornate spiny lobster Panulirus ornatus (Fabricius, 1798) in ...the South-East Asian archipelago from Vietnam to Australia. Partial mitochondrial DNA control region and 10 polymorphic microsatellites did not detect genetic structure of 216 wild P. ornatus samples from Australia, Indonesia and Vietnam. Analyses show no evidence for genetic differentiation among populations (mtDNA control region sequences ΦST = -0.008; microsatellite loci FST = 0.003). A lack of evidence for regional or localized mtDNA haplotype clusters, or geographic clusters of microsatellite genotypes, reveals a pattern of high gene flow in P. ornatus throughout the South-East Asian Archipelago. This lack of genetic structure may be due to the oceanography-driven connectivity of the pelagic lobster larvae between spawning grounds in Papua New Guinea, the Philippines and, possibly, Indonesia. The connectivity cycle necessitates three generations. The lack of genetic structure of P. ornatus population in the South-East Asian archipelago has important implications for the sustainable management of this lobster in that the species within the region needs to be managed as one genetic stock.
Extracellular electron uptake (EEU) is the ability of microbes to take up electrons from solid-phase conductive substances such as metal oxides. EEU is performed by prevalent phototrophic bacterial ...genera, but the electron transfer pathways and the physiological electron sinks are poorly understood. Here we show that electrons enter the photosynthetic electron transport chain during EEU in the phototrophic bacterium Rhodopseudomonas palustris TIE-1. Cathodic electron flow is also correlated with a highly reducing intracellular redox environment. We show that reducing equivalents are used for carbon dioxide (CO
) fixation, which is the primary electron sink. Deletion of the genes encoding ruBisCO (the CO
-fixing enzyme of the Calvin-Benson-Bassham cycle) leads to a 90% reduction in EEU. This work shows that phototrophs can directly use solid-phase conductive substances for electron transfer, energy transduction, and CO
fixation.
Ecosystem engineering in space and time Hastings, Alan; Byers, James E; Crooks, Jeffrey A ...
Ecology letters,
February 2007, Letnik:
10, Številka:
2
Journal Article
Recenzirano
The ecosystem engineering concept focuses on how organisms physically change the abiotic environment and how this feeds back to the biota. While the concept was formally introduced a little more than ...10 years ago, the underpinning of the concept can be traced back to more than a century to the early work of Darwin. The formal application of the idea is yielding new insights into the role of species in ecosystems and many other areas of basic and applied ecology. Here we focus on how temporal, spatial and organizational scales usefully inform the roles played by ecosystem engineers and their incorporation into broader ecological contexts. Two particular, distinguishing features of ecosystem engineers are that they affect the physical space in which other species live and their direct effects can last longer than the lifetime of the organism - engineering can in essence outlive the engineer. Together, these factors identify critical considerations that need to be included in models, experimental and observational work. The ecosystem engineering concept holds particular promise in the area of ecological applications, where influence over abiotic variables and their consequent effects on biotic communities may facilitate ecological restoration and counterbalance anthropogenic influences.
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