Negative frequency dependent prey selection by two canid predators and its implications for the conservation of a threatened rodent in arid Australia

Unprecedented anthropogenic changes to biodiversity and biogeography demand a greater understanding of the consequences of altered faunal composition for ecosystem functioning. Selective predation has important, yet poorly understood effects on ecosystem stability, and can be strongly influenced by the relative frequencies of different prey types in the environment. Yet, how predators adjust their selection for prey according to their environmental frequency is often overlooked. Here, we assessed frequency dependent selection of prey by dingoes and foxes in the Australian desert, biannually, across a nine-year period (2007-2016). Both predators exhibited potentially destabilizing, negative frequency dependent selection for prey. Foxes persisted to preferentially consume a threatened, native rodent (Notomys fuscus) when it was environmentally scarce. Bolstered by the observation that N.fuscus occurs at low densities in areas where foxes are common, our results suggest that N.fuscus is particularly vulnerable to predation by this predator; possibly because it is naive and/or lacks adaptations to avoid or escape predation by the relatively recently introduced fox. Dingoes tended to consume reptiles when they were scarce; potentially constituting a conservation concern if selected reptilian taxa are threatened. Foxes avoided, thus were unlikely to control populations of overabundant kangaroos, while both foxes and dingoes showed a preference for, and may therefore control populations of invasive rabbits. The integration of our results into the relative suites of (de)stabilizing influences exerted by dingoes and foxes is important to provide a more dynamic insight into how each predator impacts their naturally fluctuating ecosystems

Agricultural management intensity determines the strength of weed seed predation

Agricultural intensification both increases disturbances at the field level and reduces habitat heterogeneity at the landscape level and this can have detrimental effects on biodiversity-driven ecosystem services. A few studies have shown that agricultural intensification can diminish the ecosystem service of weed seed predation, but it is not known to what extent availability of crop and non-crop habitat can provide disturbance refugia for weed seed predators and how those effects cascade to ecosystem service provisioning. Using data from 13 fields in Southern Sweden, we first combined diet preference traits, activity density and metabolic theory, in order to develop a metric that approximates the community strength of seed predation. We then explored how the impact of field management intensity and habitat refugia on seed card predation rates mediated by weed seed availability and the metric of community strength of seed predation. We found that increasing field management intensity directly reduced seed card predation rates and weed seed availability and that reduced weed seed availability in turn impaired the community strength of seed predation. This suggests an indirect mechanism by which field management limits seed predator potential for weed seed predation. We found no evidence that either crop or non-crop refugia can increase seed card predation rates or community strength of seed predation during dis-turbances in the crop. Consequently, weed seed predation can be promoted by reducing disturbances at the field level, regardless of the availability of disturbance refugia in the landscape. Reduction of field management in-tensity can directly increase weed seed predation and indirectly seed predator communities' potential for weed seed predation by increasing weed seed availability. Future research is needed to explore if supporting a diversity of non-competitive weeds to enhance seed availability can improve the suppression of dominant and competitive weed species

Bringing Coherence to Multistate Charter Leadership: A Collective Case Study

Multistate networks are arguably the purest expression of the charter sector’s original promise as an engine of innovation within the public school system. On its face, this contention may appear somewhat counterintuitive; the proliferation of schools affiliated with charter management organizations (CMOs) that have siphoned market share away from standalone, community-based operators is often faulted for bringing homogeneity to a corner of the education landscape that once valorized pluralism. Replicating networks that expand their proven models into more than one state, however, are subject to divergent policy landscapes, operational conditions, and community expectations. Accordingly, in order to comport with the dictates of discrete sets of external demands, the leaders of multistate networks necessarily preside over a rolling set of limited experiments through which they are able to assess the relative efficacy of varying approaches to educating students. With the public policy and private philanthropic incentive structures continuing to tilt in favor of replication, and with multistate operators generally struggling to match the success of their more geographically compact peers, it is imperative that leaders of these unique organizations understand how to meet the needs of their communities while simultaneously cultivating the sense of collective mission that promotes effective operation. This collective case study explores how the leaders of five multistate networks attempt to create coherence within their organizations notwithstanding these materially different environmental conditions. Data from interviews, observations, and artifacts were triangulated, and the resulting analysis revealed commonalities, distinctions, and trends that illuminate how these leaders navigate the barriers that imperil the creation of coherence within the multistate construct. This study assesses the leadership moves that the chief executives of multistate networks make when attempting to create coherence and proposes a novel categorization scheme that classifies these strategies as either ideological, structural, or interpersonal in nature. This study also provides a composite picture of the successful multistate charter leader by synthesizing the key attributes possessed by the study participants, explaining how they exercise humility and finesse while using the serial experimentation compelled by the multistate framework to seek out opportunities to drive continuous improvement throughout their networks. Examined through a conceptual framework that ties together the literature on coherence in educational organizations and charter school replication, these findings demonstrate how multistate leaders engage stakeholders based in their satellite regions in a dynamic process of calibrating the appropriate fit between network model and local conditions. Implications from this study are relevant to the policymakers and funders who have continued to provide regulatory and financial support to operators undertaking interstate expansion efforts, to the current and prospective leaders of multistate CMOs who are being entrusted to create high-quality learning environments for students in far-flung communities, and to the superintendents of traditional public school districts who can draw lessons from the manner in which this study’s participants are consistently experimenting, evaluating, and adapting

Resilience of ecosystem processes: a new approach shows that functional redundancy of biological control services is reduced by landscape simplification

Functional redundancy can increase the resilience of ecosystem processes by providing insurance against species loss and the effects of abundance fluctuations. However, due to the difficulty of assessing individual species' contributions and the lack of a metric allowing for a quantification of redundancy within communities, few attempts have been made to estimate redundancy for individual ecosystem processes. We present a new method linking interaction metrics with metabolic theory that allows for a quantification of redundancy at the level of ecosystem processes. Using this approach, redundancy in the predation on aphids and other prey by natural enemies across a landscape heterogeneity gradient was estimated. Functional redundancy of predators was high in heterogeneous landscapes, low in homogeneous landscapes and scaled with predator specialisation. Our approach allows quantifying functional redundancy within communities and can be used to assess the role of functional redundancy across a wide variety of ecosystem processes and environmental factors

Functional redundancy of weed seed predation is reduced by intensified agriculture

Intensified agriculture, a driver of biodiversity loss, can diminish ecosystem functions and their stability. Biodiversity can increase functional redundancy and is expected to stabilize ecosystem functions. Few studies, however, have explored how agricultural intensity affects functional redundancy and its link with ecosystem function stability. Here, within a continental-wide study, we assess how functional redundancy of seed predation is affected by agricultural intensity and landscape simplification. By combining carabid abundances with molecular gut content data, functional redundancy of seed predation was quantified for 65 weed genera across 60 fields in four European countries. Across weed genera, functional redundancy was reduced with high field management intensity and simplified crop rotations. Moreover, functional redundancy increased the spatial stability of weed seed predation at the field scale. We found that ecosystem functions are vulnerable to disturbances in intensively managed agroecosystems, providing empirical evidence of the importance of biodiversity for stable ecosystem functions across space.Within a continent-wide study, we assess the impact of agricultural intensity and landscape simplification on the functional redundancy of weed seed predation. We found that functional redundancy was reduced with high field management intensity and simplified crop rotations. Additionally, high functional redundancy increased the spatial stability of weed seed predation, underscoring the importance of biodiversity in maintaining stable ecosystem functions across space in intensively managed agroecosystems.imag

Climate change and ecological intensification of agriculture in sub-Saharan Africa-A systems approach to predict maize yield under push-pull technology

Assessing effects of climate change on agricultural systems and the potential for ecological intensification to increase food security in developing countries is essential to guide management, policy-making and future research. 'Push-pull' technology (PPT) is a poly-cropping design developed in eastern Africa that utilizes plant chemicals to mediate plant-insect interactions. PPT application yields significant increases in crop productivity, by reducing pest load and damage caused by arthropods and parasitic weeds, while also bolstering soil fertility. As climate change effects may be species-and/or context-specific, there is need to elucidate how, in interaction with biotic factors, projected climate conditions are likely to influence future functioning of PPT. Here, we first reviewed how changes in temperature, precipitation and atmospheric CO2 concentration can influence PPT components (i.e., land use, soils, crops, weeds, diseases, pests and their natural enemies) across sub-Saharan Africa (SSA). We then imposed these anticipated responses on a landscape-scale qualitative mathematical model of maize production under PPT in eastern Africa, to predict cumulative, structure-mediated impacts of climate change on maize yield. Our review suggests variable impacts of climate change on PPT components in SSA by the end of the 21st century, including reduced soil fertility, increased weed and arthropod pest pressure and increased prevalence of crop diseases, but also increased biological control by pests' natural enemies. Extrapolating empirical evidence of climate effects to predict responses to projected climate conditions is mainly limited by a lack of mechanistic understanding regarding single and interactive effects of climate variables on PPT components. Model predictions of maize yield responses to anticipated impacts of climate change in eastern Africa suggest predominantly negative future trends. Nevertheless, maize yields can be sustained or increased by favourable changes in system components with less certain future behaviour, including higher PPT adoption, preservation of field edge density and agricultural diversification beyond cereal crops

Introduction to Quantum Algorithms for Physics and Chemistry

In this introductory review, we focus on applications of quantum computation to problems of interest in physics and chemistry. We describe quantum simulation algorithms that have been developed for electronic-structure problems, thermal-state preparation, simulation of time dynamics, adiabatic quantum simulation, and density functional theory.Comment: 44 pages, 5 figures; comments or suggestions for improvement are welcom

Harnessing nature-based solutions for smallholder plant health in a changing climate

The impacts of climate change on resource-poor farmers are especially severe and include increased challenges with food security and food safety. This report explores how linking the frameworks of nature-based solutions, integrated pest management (IPM), and One Health can facilitate the design of climate-resilient plant health systems, with particular benefits for reduced pesticide use and exposure. Climate-smart approaches to IPM are proposed as a means to reduce emerging risks from pest insects, nematodes, weeds, and diseases under climate change. We elaborate the main climate change threats – and adaptation options – for five key nature-based solutions central to IPM: host plant resistance and tolerance, habitat manipulation, biological control, semiochemical control, and the use of biopesticides. We conclude by laying out a road map for ‘climate-smart IPM’, which outlines the types of support required for practical implementation, such as climate-informed advisory services, information and communication technology, and policy. While emphasis throughout is placed on smallholder production systems – particularly for sub-Saharan Africa – the principles of climate-smart IPM can be considered relevant to crop production generally

High-performance Bragg gratings in chalcogenide rib waveguides written with a modified Sagnac interferometer

This paper was published in Journal of the Optical Society of America B-Optical Physics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=josab-23-7-1323. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Mehrdad Shokooh-Saremi, Vahid G. Ta'eed, Neil J. Baker, Ian C. M. Littler, David J. Moss, Benjamin J. Eggleton, Yinlan Ruan, and Barry Luther-Davie

Can water exclusion limit the ecological impact of invasive cane toads?

The proliferation of artificial water points (AWP) to enhance livestock production has fundamentally changed the ecology of dryland ecosystems. By providing a constant source of surface water, AWP can affect the density, distribution and activity of water-dependent native and invasive species. Thus, AWP have the potential to facilitate trophic and competitive interactions, thereby amplifying their impact on the structure and composition of resident animal and plant communities. Recent studies suggest that a strategic manipulation of surface water availability in dryland biomes could be a useful management approach to reduce the negative impacts of native herbivores on vegetation and to mitigate the spread and impact of water-dependent invasive species. However, there is only limited empirical evidence that water exclusion could provide benefits for the ecology and community structure of dryland ecosystems by returning them to their natural water-limited state. Especially for invasive species where the effectiveness of a large scale water exclusion strategy has not been sufficiently evaluated. This is particularly important for high-impact invasive species such as the cane toad Rhinella marina, an anuran that is currently invading northern and arid regions of Australia. Due to their potent chemical defences cane toads put a wide range of native predators at risk of toxic ingestion. During periods of prolonged hot and dry conditions which typically prevail in arid regions, cane toads need regular access to water to survive. In rangeland areas of the Tanami Desert in Australia’s Northern Territory, the existence of AWP fitted with two types of reservoirs provided an opportunity to examine whether exclusion from access to surface water at AWP could limit the abundance and ecological impacts of cane toads. Cane toads could readily access surface water at AWP fitted with earthen dams as reservoirs but cane toads could not access surface water at AWP fitted with water tanks. This study has implications for the management of cane toads in Australia’s arid and semi-arid rangelands. The findings demonstrate that excluding water-dependent species from access to surface water at AWP by changing the water reservoir system from traditionally used earthen dams to water tanks results in a reduction of both their population densities and ecological impacts