Brian Leung

McGill University | McGill

Estimating biodiversity change across the planet in the context of widespread human modification is a critical challenge. Here, we review how biodiversity has changed in recent decades across scales and taxonomic groups, focusing on four diversity metrics: species richness, temporal turnover, spatial beta-diversity and abundance. At local scales, c...

Background Biological invasions threaten the functioning of ecosystems, biodiversity, and human well-being by degrading ecosystem services and eliciting massive economic costs. The European Union has historically been a hub for cultural development and global trade, and thus, has extensive opportunities for the introduction and spread of alien spec...

Background: Biological invasions threaten the functioning of ecosystems, biodiversity, and human well-being by degrading ecosystem services and eliciting massive economic costs. The European Union, as the world’s third-largest economy, has historically been a hub for cultural development and global trade, and thus, has extensive opportunities for t...

Canals provide wide-ranging economic benefits, while also serving as corridors for the introduction and spread of aquatic alien species, potentially leading to negative ecological and economic impacts. However, to date, no comprehensive quantifications of the reported economic costs of these species have been done. Here, we used the InvaCost databa...

1. Invasive alien species are one of the major threats to global biodiversity, ecosystem integrity, natures contribution to people and human health. While scenarios about potential future developments have been available for other global change drivers for quite some time, we largely lack an understanding of how biological invasions might unfold in...

Future dynamics of biological invasions are highly uncertain because they depend on multiple environmental, societal and socio-economic drivers. We adopted a qualitative scenario approach to explore the future of invasive alien species (IAS) in Europe and created an overall strategy for their management that considers different plausible future dev...

Unlabelled: The extent and impacts of biological invasions on biodiversity are largely shaped by an array of socio-economic and environmental factors, which exhibit high variation among countries. Yet, a global analysis of how these factors vary across countries is currently lacking. Here, we investigate how five broad, country-specific socio-econ...

Biological invasions are one of the main threats to biodiversity within protected areas (PAs) worldwide. Meanwhile, the resilience of PAs to invasions remains largely unknown. Consequently, providing a better understanding of how they are impacted by invasions is critical for informing policy responses and optimally allocating resources to preventi...

Ecological and socioeconomic impacts from biological invasions are rapidly escalating worldwide. While effective management underpins impact mitigation, such actions are often delayed, insufficient or entirely absent. Presently, management delays emanate from a lack of monetary rationale to invest at early invasion stages, which precludes effective...

The management of introduced species, whether kudzu or zebra mussels, is costly and complex. Now, a paper reports a workable, effective solution that harnesses network analyses of ecological phenomena.

Many plant traits covary with environmental gradients, reflecting shifts in adaptive strategies under changing conditions and thus providing information about potential consequences of future environmental change for vegetation and ecosystem functioning. Despite extensive efforts to map trait-environment relationships, the evidence remains heteroge...

As strategic transport infrastructures, canals provide wide-ranging economic benefits as well as save energy and reduce CO2 emissions. At the same time, by connecting previously biogeographically-isolated systems, they serve as corridors for the introduction and spread of aquatic alien species, potentially leading to unforeseen ecological and econo...

Urban trees are important nature‐based solutions for future well‐being and liveability but are at high risk of mortality from insect pests. In the United States (US), 82% of the population live in urban settings and this number is growing, making urban tree mortality a matter of concern for most of its population. Until now, the magnitudes and spat...

Contrary to previous studies, an analysis of 7,000 plant and animal species shows that species size is unrelated to changes in their population abundance.

Scenario analysis has emerged as a key tool to analyze complex and uncertain future socio-ecological developments. However, currently existing global scenarios (narratives of how the world may develop) have neglected biological invasions, a major threat to biodiversity and the economy. Here, we use a novel participatory process to develop a diverse...

Invasive species can have severe impacts on ecosystems, economies, and human health. Though the economic impacts of invasions provide important foundations for management and policy, up-to-date syntheses of these impacts are lacking. To produce the most comprehensive estimate of invasive species costs within North America (including the Greater Ant...

Urban trees are important nature-based solutions for future wellbeing and livability but are at high risk of mortality from insect pests. United States (US) urbanization levels are already at 82% and are growing, making urban tree mortality a matter of concern for the majority of its population. Until now, the magnitudes and spatial distributions o...

Ecological and socioeconomic impacts from biological invasions are rapidly escalating worldwide. While effective management underpins impact mitigation, such actions are often delayed, insufficient or entirely absent. Presently, management delays emanate from a lack of monetary rationale to invest at early invasion stages, which precludes effective...

Communities are shaped by a variety of ecological and environmental processes, each acting at different spatial scales. Seminal research on rocky shores highlighted the effects of consumers as local determinants of primary productivity and community assembly. However, it is now clear that the species interactions shaping communities at local scales...

Biological invasions are one of the main threats to biodiversity within protected areas (PAs) worldwide. Meanwhile, the resilience of PAs along with their capacity to mitigate impacts from invasions remains largely unknown. Filling this knowledge gap is therefore critical for informing policy responses and optimally allocating resources invested in...

The extent and impacts of biological invasions on biodiversity are largely shaped by an array of socio-ecological predictors, which exhibit high variation among countries. Yet a global synthetic perspective of how these factors vary across countries is currently lacking. Here, we investigate how a set of five socio-ecological predictors (Governance...

A Correction to this paper has been published: https://doi.org/10.1038/s41586-020-2920-6.

Scenario analysis has emerged as a key tool to analyze complex and uncertain future socio-ecological developments. However, current global scenarios (narratives of how the world may develop) have neglected biological invasions, a major threat to biodiversity and the economy. We used a novel participatory process to develop a diverse set of global b...

Behavioural lateralization, the asymmetric expression of cognitive functions, is reported to enhance key fitness-relevant traits such as group coordination, multitasking and predator escape. Therefore, studies reporting negative effects on lateralization in fish due to environmental stressors such as ocean acidification, hypoxia and pollutants are...

Biological invasions are a major threat to global biodiversity with particularly strong implications for island biodiversity. Much research has been dedicated towards understanding historic and current changes in alien species distribution and impacts on islands and potential changes under future climate change. However, projections of how alien sp...

Understanding the likely future impacts of biological invasions is crucial yet highly challenging given the multiple relevant environmental, socio‐economic and societal contexts and drivers. In the absence of quantitative models, methods based on expert knowledge are the best option for assessing future invasion trajectories. Here, we present an ex...

Rapid response strategies are necessary to effectively manage non-indigenous species. After detection, only few species persist and potentially cause harm. To help prioritize resources, we employed a multispecies, geographically explicit approach, focusing on non-indigenous aquarium fish establishment in the USA. We modeled casual (i.e. temporary)...

Nutrient subsidies support high primary productivity, increasing herbivore abundance and influencing their top‐down control of producers. Wind‐driven upwelling events deliver cold nutrient‐rich water to coastlines, supporting highly productive marine environments. Results from studies comparing ecological processes across upwelling regimes are mixe...

While generality is often desirable in ecology, customized models for individual species are thought to be more predictive by accounting for context‐specificity. However, fully customized models require more information for focal species. We focus on pest spread, and ask: how much does predictive power differ between generalized and customized mode...

Estimating α‐diversity and species distributions provide baseline information to understand factors such as biodiversity loss and erosion of ecosystem services. Yet, species surveys typically cover a small portion of any country's landmass. Public, global databases could help, but contain biases. Thus, the magnitude of bias should be identified and...

The PREPRINT is publicly available here: https://doi.org/10.32942/osf.io/6kcwa ------------------------------------------------------------------------------------------------------------------------------------------------------ABSTRACT: Behavioural lateralisation, defined as the asymmetric expression of cognitive functions, is reported to enhance...

1.Key questions in invasion biology include where will a non-indigenous species (NIS) establish, and how will it affect biodiversity? Scientists have addressed the first question, largely through correlating species’ distributions with environmental factors (i.e. species distribution models, SDM). Conceptually, SDMs reflect a species’ abiotic const...

Aim: To evaluate how the establishment risk of freshwater fish species from the aquarium trade will change under a climate change scenario forecast for the year 2050. Location: North America. Methods: In order to estimate changes in the magnitude of risk across geography and across different species in the aquarium pathway, we considered an integra...

Considerable controversy exists over the nature of the “Biodiversity Crisis.” While some studies suggest declining diversity, others suggest no loss on average. Population declines necessarily precede species loss and may therefore be a more sensitive metric. We examine trends in abundances to test the hypotheses: (1) losses are experienced disprop...

Models have been well developed describing human movements as vectors of the spread of non-indigenous species (NIS). However, to be maximally useful, predictions need to be integrated with management models of how different policies change human behaviour and lead to concurrent changes in invasion risk. Using the dispersal of freshwater organisms b...

We tested whether a general spread model could capture macroecological patterns across all damaging invasive forest pests in the United States. We showed that a common constant dispersal kernel model, simulated from the discovery date, explained 67.94% of the variation in range size across all pests, and had 68.00% locational accuracy between predi...

Aim To synthesize the species distribution modelling (SDM) literature to inform which variables have been used in MaxEnt models for different taxa and to quantify how frequently they have been important for species’ distributions. Location Global. Methods We conducted a quantitative synthesis analysing the contribution of over 400 distinct enviro...

The Indo-Pacific Red Lionfish was first reported off the Florida coast in 1985, following which it has spread across much of the SE USA, Gulf of Mexico, and Caribbean Sea. Lionfish negatively impact fish and invertebrate assemblages and abundances, thus further spread is cause for concern. To date, the fish has not been reported on the Pacific coas...

Predicting the spread of organisms is of fundamental and applied interest in ecology. We tested whether a general spread model could capture macroecological patterns across all damaging invasive forest pests in the United States. We showed that a common constant dispersal kernel model, simulated from the discovery date, explained 67.94% of the vari...

The development of risk assessment methods for invasive species is needed to prioritize management of invaders towards high risk species and likely locations for establishment. The concern regarding such species has been exacerbated by the climate changes currently underway, which could shift species distributions and change the invaders’ ability t...

We review and synthesize information on invasions of nonnative forest insects and diseases in the United States, including their ecological and economic impacts, pathways of arrival, distribution within the United States, and policy options for reducing future invasions. Nonnative insects have accumulated in United States forests at a rate of ∼2.5...

Environmental distance metrics quantify environmental similarity between locations using a number of environmental variables. They are commonly applied in aquatic non-indigenous species risk assessments to assess the relative risk of species transfer between different location pairs. Despite their application in governmental risk assessments global...

Letter from several members of the EPA Science Advisory Board Panel on Ballast Water and the National Acedemy of Sciences/National Research Council Committee on Ballast Water claiming that the EPA misstated the SAB Panel's findings as support for its proposed discharge standards

Parasites can play an important role in biological invasions. While introduced species often lose parasites from their native range, they can also accumulate novel parasites in their new range. The accumulation of parasites by introduced species likely varies spatially, and more parasites may shift to new hosts where parasite diversity is high. Con...

Factors associated with the burden of influenza among vulnerable populations have mainly been identified using statistical methodologies. Complex simulation models provide mechanistic explanations, in terms of spatial heterogeneity and contact rates, while controlling other factors and may be used to better understand statistical patterns and, ulti...

Predictions of large-scale ecological patterns and processes are critically dependent on the type of data available and our ability to make inferences using them. This is exemplified by prediction of the spread of invasive species, a global driver of environmental change. Here, data often consist of records of where species are found, however at lo...

Non-indigenous species (NIS) establishments are a growing concern. Current quantitative methods for NIS risk assessment generally focus on only one species or only one of the main drivers of establishment (propagule pressure, environmental suitability, or species’ traits). There is a need for quantitative models that estimate establishment probabil...

1.Predictive models in ecology are important for guiding policy and management. However, they are necessarily abstractions of natural systems, making predictive validation imperative. Models which make predictions about binary outcomes (eg. Species distribution models, population viability analysis, disease/invasion models) are widespread in the ec...

Invasive species policies are often directed at pathways of introduction, yet few analyses have examined risk at the pathway level. We synthesize the best available economic and ecological information surrounding International Standards for Phytosanitary Measures No 15 (ISPM15), a pathway-level international phytosanitary policy for treatment of wo...

Predicting population establishment based on initial population size is a theoretically and empirically challenging problem whose resolution informs a multitude of applications. Indeed, it is a central problem in the management of introduced, endangered, harvested, and pathogenic organisms. We focus here on introduced species. We synthesize the cur...

We address criticism that the Transport, Establishment, Abundance, Spread, Impact (TEASI) framework does not facilitate objective mapping of risk assessment methods nor defines best practice. We explain why TEASI is appropriate for mapping, despite inherent challenges, and how TEASI offers considerations for best practices, rather than suggesting o...

Aim: To build and assess pathway-level non-indigenous species (NIS) establishment curves generated using a propagule pressure (PP) proxy and historical establishment data. Location: North America Methods: Our analysis examines the utility and behaviour of pathway-level NIS establishment curves that relate species-level PP to establishment probabili...

We are now beginning to understand the role of intraspecific diversity on fundamental ecological phenomena. There exists a paucity of knowledge, however, regarding how intraspecific, or genetic diversity, may covary with other important factors such as propagule pressure. A combination of theoretical modelling and experimentation was used to explor...

Knowledge of dispersal and establishment during the early stages of invasion is essential for allocating monitoring effort, detecting nascent populations and predicting spread. The scarcity of these data, however, provides little guidance for monitoring programs. Here we present data on the adult distribution and the subsequent pattern of larval re...

Modeling plays a critical role in mitigating impacts of seasonal influenza epidemics. Complex simulation models are currently at the forefront of evaluating optimal mitigation strategies at multiple scales and levels of organization. Given their evaluative role, these models remain limited in their ability to predict and forecast future epidemics l...

Forecasts of several past influenza seasons and the observed data on past epidemics (black bars, number of laboratory positive samples), assuming a general infectiousness profile function and scalar for pre-existing immunity of 0.25. Forecasts were based on best-fit baseline model in which only the level of vaccination coverage was changed for each...

Deviation metric for overall fit in forecasts of several past influenza seasons. Overall fit was calculated under dynamic (blue) and static (red) forecasts assuming a general infectiousness profile function and scalar of 0.25 for pre-existing immunity. The metric was calculated as the % error between observed and simulated epidemics with 95% confid...

Infectiousness profiles based on the Ferguson model (general strain) and Liao et al. [35])(specific). Curves are normalized such that area under the curve equals 1. (TIFF)

Forecasts of several past influenza seasons and the observed data on past epidemics (black bars, number of laboratory positive samples), assuming a specific infectiousness profile function and scalar for pre-existing immunity of 0.25. Forecasts were based on best-fit baseline model in which only the level of vaccination coverage was changed for eac...

Deviation metric for peak week in forecasts of several past influenza seasons. Dynamic (blue) and static (red) forecasts were considered here assuming the general infectiousness profile function and scalar of 0.25 for pre-existing immunity. See legend of Fig. 4 for further details about x-axis. Deviation in peak week was calculated as difference in...

Deviation metric for absolute intensity in forecasts of several past influenza seasons. Dynamic (blue) and static (red) forecasts were considered here assuming the specific infectiousness profile function and scalar of 0.25 for pre-existing immunity. See legend of Fig. 4 for details about x-axis. Absolute intensity was calculated at peak week there...

Model fitting to observed data for reference influenza season (1998–1999) under different infectiousness profile functions and scalar for pre-existing immunity set to 0.25. Observed data are presented as the number (black solid lines) and % positive (dashed black line) of laboratory-confirmed positive samples. X-axis is the number of weeks since st...

Deviation metric for epidemic duration in forecasts of several past influenza seasons. Dynamic (blue) and static (red) forecasts were considered here assuming the general infectiousness profile function and scalar of 0.25 for pre-existing immunity. See legend of Fig. 4 for further details about x-axis. Deviation in epidemic duration was calculated...

Simulated age-based clinical attack rates (age categories of 0–100 in 5-year intervals) under different infectiousness profiles (panels) and scalar for pre-existing immunity (colored bars). Values were based on all available data from observed epidemics and 50 simulated epidemics with initial conditions as mentioned in the main text. (TIFF)

Supplementary material. (DOC)

Observed (points) and simulated (bars) age-based clinical attack rates (age categories of 0–17 and 18+) under different infectiousness profiles and scalar for pre-existing immunity. Values were based on all available data from observed epidemics and 50 simulated epidemics with initial conditions as mentioned in the main text. (TIFF)

Deviation metric for overall fit in forecasts of several past influenza seasons. Overall fit was calculated under dynamic (blue) and static (red) forecasts assuming a specific infectiousness profile function and scalar of 0.25 for pre-existing immunity. The metric was calculated as the % error between observed and simulated epidemics with 95% confi...

Deviation metric for peak week in forecasts of several past influenza seasons. Dynamic (blue) and static (red) forecasts were considered here assuming the specific infectiousness profile function and scalar of 0.25 for pre-existing immunity. See legend of Fig. 4 for further details about x-axis. Deviation in peak week was calculated as difference i...

Deviation metric for absolute intensity in forecasts of several past influenza seasons. Dynamic (blue) and static (red) forecasts were considered here assuming the general infectiousness profile function and scalar of 0.25 for pre-existing immunity. See legend of Fig. 4 for details about x-axis. Absolute intensity was calculated at peak week theref...