Showing papers by "David L. Strayer published in 2020"

A conceptual map of invasion biology: Integrating hypotheses into a consensus network

Abstract: BACKGROUND AND AIMS: Since its emergence in the mid‐20th century, invasion biology has matured into a productive research field addressing questions of fundamental and applied importance. Not only has the number of empirical studies increased through time, but also has the number of competing, overlapping and, in some cases, contradictory hypotheses about biological invasions. To make these contradictions and redundancies explicit, and to gain insight into the field’s current theoretical structure, we developed and applied a Delphi approach to create a consensus network of 39 existing invasion hypotheses. RESULTS: The resulting network was analysed with a link‐clustering algorithm that revealed five concept clusters (resource availability, biotic interaction, propagule, trait and Darwin’s clusters) representing complementary areas in the theory of invasion biology. The network also displays hypotheses that link two or more clusters, called connecting hypotheses, which are important in determining network structure. The network indicates hypotheses that are logically linked either positively (77 connections of support) or negatively (that is, they contradict each other; 6 connections). SIGNIFICANCE: The network visually synthesizes how invasion biology’s predominant hypotheses are conceptually related to each other, and thus, reveals an emergent structure – a conceptual map – that can serve as a navigation tool for scholars, practitioners and students, both inside and outside of the field of invasion biology, and guide the development of a more coherent foundation of theory. Additionally, the outlined approach can be more widely applied to create a conceptual map for the larger fields of ecology and biogeography.

A proposed unified framework to describe the management of biological invasions

Abstract: Managing the impacts of invasive alien species (IAS) is a great societal challenge A wide variety of terms have been used to describe the management of invasive alien species and the sequence in which they might be applied This variety and lack of consistency creates uncertainty in the presentation and description of management in policy, science and practice Here we expand on the existing description of the invasion process to develop an IAS management framework We define the different forms of active management using a novel approach based on changes in species status, avoiding the need for stand-alone descriptions of management types, and provide a complete set of potential management activities We propose a standardised set of management terminology as an emergent feature of this framework We identified eight key forms of management: (1) pathway management, (2) interception, (3) limits to keeping, (4) secure keeping, (5) eradication, (6) complete reproductive removal, (7) containment and (8) suppression We recognise four associated terms: prevention; captive management; rapid eradication; and long-term management, and note the use of impact mitigation and restoration as associated forms of management We discuss the wider use of this framework and the supporting activities required to ensure management is well-targeted, cost-effective and makes best use of limited resources

Need for routine tracking of biological invasions.

Abstract: Jan Pergl , ∗ Petr Pyšek, Franz Essl, Jonathan M. Jeschke , Franck Courchamp , Juergen Geist , Martin Hejda, Ingo Kowarik, Aileen Mill, Camille Musseau, Pavel Pipek , Wolf-Christian Saul, Menja von Schmalensee, and David Strayer 14,15 Czech Academy of Sciences, Institute of Botany, Department of Invasion Ecology, CZ-252 43, Průhonice, Czech Republic Department of Ecology, Faculty of Science, Charles University, Viničná 7, CZ-128 44, Prague, Czech Republic Centre for Invasion Biology, Department of Botany and Zoology & Department of Mathematical Sciences, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa Division of Conservation Biology, Vegetation and Landscape Ecology, Department of Botany and Biodversity Research, University of Vienna, 1030, Wien, Austria Freie Universität Berlin, Department of Biology, Chemistry, Pharmacy, Institute of Biology, Königin-Luise-Straße 1–3, 14195, Berlin, Germany Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 310, 12587, Berlin, Germany Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Königin-Luise-Straße 2–4, 14195, Berlin, Germany Université Paris-Saclay, CNRS, AgroParisTech, Ecologie Systématique Evolution, 91405, Orsay, France Technical University of Munich, Aquatic Systems Biology Unit, Muehlenweg 22, 85454, Freising, Germany Department of Ecology, Technische Universität Berlin, Rothenburgstr. 12, 12165, Berlin, Germany Modelling Evidence and Policy Group, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K. West Iceland Nature Research Centre, Hafnargata 3, 340, Stykkishólmur, Iceland Faculty of Life and Environmental Sciences, University of Iceland, Askja, Sturlugata 7, 102, Reykjav́ık, Iceland Cary Institute of Ecosystem Studies, P.O. Box AB, 2801 Sharon Turnpike, Millbrook, NY, 12545, U.S.A. Graham Sustainability Institute, University of Michigan, 625 East Liberty Street, Ann Arbor, MI, 48104, U.S.A.

Non‐native species have multiple abundance–impact curves

Abstract: The abundance-impact curve is helpful for understanding and managing the impacts of non-native species. Abundance-impact curves can have a wide range of shapes (e.g., linear, threshold, sigmoid), each with its own implications for scientific understanding and management. Sometimes, the abundance-impact curve has been viewed as a property of the species, with a single curve for a species. I argue that the abundance-impact curve is determined jointly by a non-native species and the ecosystem it invades, so that a species may have multiple abundance-impact curves. Models of the impacts of the invasive mussel Dreissena show how a single species can have multiple, noninterchangeable abundance-impact curves. To the extent that ecosystem characteristics determine the abundance-impact curve, abundance-impact curves based on horizontal designs (space-for-time substitution) may be misleading and should be used with great caution, it at all. It is important for scientists and managers to correctly specify the abundance-impact curve when considering the impacts of non-native species. Diverting attention from the invading species to the invaded ecosystem, and especially to the interaction between species and ecosystem, could improve our understanding of how non-native species affect ecosystems and reduce uncertainty around the effects of management of populations of non-native species.

Long‐term variability and density dependence in Hudson River Dreissena populations

Abstract: 1. We used a 27-year record of Dreissena populations in the freshwater tidal Hudson River to describe interannual variation in population density, body size, and body condition; estimate long-term variation in recruitment, survivorship, and shell growth; and assess possible controls on the populations. 2. Dreissena populations in the Hudson have been highly variable, with interannual ranges of c. 100-fold in abundance and biomass, and 7-fold in mean body mass. This large interannual variation arises from both long-term trends and 2–5-year cycles. 3. Long-term trends include the 2008 appearance of the quagga mussel (Dreissena rostriformis), which still forms a small part (<10%) of the dreissenid community, and a decline in zebra mussel body size. The decline in body size was caused by a long-term decline in adult survivorship rather than a decline in rates of shell growth. We could detect no long-term trends in adult abundance or spread of Dreissena onto soft sediments in the Hudson. 4. We observed persistent, strong cycles in adult abundance and body size. These were driven by the appearance and decay of eight dominant year classes over the 27 years of our study, and were a result of temporal variation in recruitment rather than temporal variation in survivorship. The observed strongly irregular recruitment appears to arise from strong adult–larval interactions, and is consistent with previous simulation model results showing that interactions between adults and larvae can drive persistent cycling. 5. We found evidence that negative density dependence affects recruitment, somatic growth, and body condition of Dreissena in the Hudson. Warm summers may also cause high adult mortality. 6. We put our results into the context of a conceptual model of Dreissena population dynamics, and argue that neither the dynamics nor the controls of populations of these important invaders is known satisfactorily.

Resting-State Posterior Alpha Power Changes with Prolonged Exposure in a Natural Environment.

Abstract: Exposure to environments that contain natural features can benefit mood, cognition, and physiological responses. Previous research proposed exposure to nature restores voluntary attention – attention that is directed towards a task through top down control. Voluntary attention is limited in capacity and depletes with use. Nature provides unique stimuli that do not require voluntary attention; therefore, the neural resources needed for attention to operate efficiently are theorized to restore when spending time in nature. Electroencephalography reflects changes in attention through fluctuations in power within specific frequencies. The current study (N = 29) measured changes in averaged resting state posterior alpha power before, during, and after a multiday nature exposure. Linear mixed-effects models revealed posterior alpha power was significantly lower during the nature exposure compared to pre-trip and post-trip testing, suggesting posterior alpha power may be a potential biomarker for differences related to exposure to natural and urban environments.

Age-Related Differences in the Cognitive, Visual, and Temporal Demands of In-Vehicle Information Systems.

Abstract: In-vehicle information systems (IVIS) refer to a collection of features in vehicles that allow motorists to complete tasks (often unrelated to driving) while operating the vehicle. These systems may interfere, to a greater extent, with older drivers' ability to attend to the visual and cognitive demands of the driving environment. The current study sought to examine age-related differences in the visual, cognitive and temporal demands associated with IVIS interactions. Older and younger drivers completed a set of common tasks using the IVIS of a representative sample of six different vehicles while they drove along a low-density residential street. Evaluation measures included a Detection Response Task (DRT), to assess both cognitive and visual attention, and subjective measures following each condition using the NASA Task Load Index (TLX). Two age cohorts were evaluated: younger drivers between 21 and 36 years of age, and older drivers between 55 and 75 years of age. Participants completed experimental tasks involving interactions with the IVIS to achieve a specific goal (i.e., using the touch screen to tune the radio to a station; using voice commands to find a specified navigation destination, etc.). Performance of tasks varied according to different modes of interaction available in the vehicles. Older drivers took longer to complete tasks, were slower to react to stimuli, and reported higher task demand when interacting with IVIS. Older drivers stand to benefit the most from advancements in-vehicle technology, but ironically may struggle the most to use them. The results document significant age-related costs in the potential for distraction from IVIS interactions on the road.

Driver Arousal and Workload Under Partial Vehicle Automation: A Pilot Study

Abstract: Semi-automated vehicles (Level-2) provide driving assistance, but they still require driver supervision to maintain safe driving. However, little is known about potential differences in drivers’ co...