Search

Aim: This study aims to quantify the patterns in compositional turnover of native and exotic ants on small islands in two oceans, and to explore whether such patterns are driven by similar environmental, geographical and potentially biotic variables. Location: Pacific and Atlantic islands. Time period: Present. Major taxa studied: Ants. Methods: We applied Multi‐Site Generalised Dissimilarity Modelling (MS‐GDM), which relates zeta diversity, the number of species shared by a given number of islands, to differences in environmental, geographical and biotic drivers. The use of zeta diversity enabled us to differentiate the contribution of rare species (shared by few islands) from those of widespread ones (shared by multiple islands) to compositional turnover. For completion, we also related species richness of insular ants per island with the same set of explanatory variables using Generalised Additive Models (GAM). Results: Pacific and Atlantic islands have similar patterns of ant species turnover and richness, albeit partly driven by different drivers. Native and exotic species turnover are mostly explained by the same set of variables in the Pacific (annual precipitation and distance to the nearest island), but not in the Atlantic (annual precipitation is a good predictor of native species turnover, but none of the variables considered in our study explained exotic species turnover). No signal of biotic interactions was detected at the insular community level. Main conclusions: Successful invasion strategies may depend on a combination of factors specific to the region in question. In the Pacific, milder environments and the absence of natives on certain islands enable exotic ants to select the same types of environment as native ants. In the harsher Atlantic Ocean, however, native ant species are likely to be well adapted to local environmental conditions, making it harder for exotics to become established. Exotic ant species, therefore, potentially rely on other attributes to establish, such as a combination of tolerance to a wide range of environmental conditions and human‐mediated colonization. [ABSTRACT FROM AUTHOR]

Aim To examine the relationship between island characteristics (area, distance to the nearest continent, climate and human population size) and ant species richness, as well as the factors underlying global geographical clustering of native and exotic ant composition on islands. Location One hundred and two islands from 20 island groups around the world. Methods We used spatial linear models that consider the spatial structure of islands to examine patterns of ant species richness. We also performed modularity analyses to identify clusters of islands hosting a similar suite of species and constructed conditional inference trees to assess the characteristics of islands that explain the formation of these island-ant groups. Results Island area was the best predictor of ant species richness. However, distance to the nearest continent was an important predictor of native ant species richness, as was human population size for exotic species richness. Native species appear slightly more modulated (i.e. well grouped in species assemblages that are present over a distinct cluster of islands) than are exotic species. Exotic species, while still exhibiting some modularity, tended to be widely distributed among island groups. Interestingly, ocean currents accounted for most of the variation in modularity and thus species composition for both native and exotic ant species. Main conclusions Contrary to previous work, both native and exotic species appeared to be confined to particular island regions, and patterns in the distribution of both native and exotic species were limited by a similar suite of factors. However, the distribution of exotic ant species appeared to be more influenced by human-related variables and less structured relative to those of native ant species, perhaps due to the long-term (and increasing) influence of human-mediated dispersal that favours exotic species. [ABSTRACT FROM AUTHOR]

Dispersal strategies are one of the most important determinants of range dynamics and a surrogate for invasiveness. We tested three inter-related hypotheses derived from demographic and ecological models: (H1) short-distance dispersal strategies arise at native range margins due to their demographic advantage; (H2) in non-native areas a high diffusion rate is favoured at the advancing range front for niche filling; (H3) environmental deterioration can increase dispersal and lead to a 'good-stay, bad-disperse' strategy. Spatially and temporally explicit rates of spread and dispersal kernels of the European starling Sturnus vulgaris were generated for its native range (Britain) using ringing records from 1909 to 2008, and for a non-native area (South Africa) using ringing data and distributional records since its introduction in 1897. There was a marked spatial and temporal variation in the rate of spread within both native and non-native ranges. In the native range the rate of spread declined with increasing distance from the species' European distribution (contradicting H1). In the non-native range the rate of spread increased with distance from the introduction locality (supporting H2). The annual rate of spread in the native range also increased significantly when environmental conditions were deteriorating as indicated by marked population declines and relatively low abundance (H3), providing clear evidence for flexible dispersal strategies based on a 'good-stay, bad-disperse' rule. Starlings' dispersal kernel followed an inverse power law and showed strong anisotropy and significant divergence between native and invasive populations, suggesting a flexible strategy comprising a dynamic response to spatial and temporal environmental variation with implications for predicting dispersal and range dynamics arising from environmental change. [ABSTRACT FROM AUTHOR]

Because invasive species threaten the integrity of natural ecosystems, a major goal in ecology is to develop predictive models to determine which species may become widespread and where they may invade. Indeed, considerable progress has been made in understanding the factors that influence the local pattern of spread for specific invaders and the factors that are correlated with the number of introduced species that have become established in a given region. However, few studies have examined the relative importance of multiple drivers of invasion success for widespread species at global scales. Here, we use a dataset of >5,000 presence/absence records to examine the interplay between climatic suitability, biotic resistance by native taxa, humanaided dispersal, and human modification of habitats, in shaping the distribution of one of the world's most notorious invasive species, the Argentine ant (Linepithema humile). Climatic suitability and the extent of human modification of habitats are primarily responsible for the distribution of this global invader. However, we also found some evidence for biotic resistance by native communities. Somewhat surprisingly, and despite the often cited importance of propagule pressure as a crucial driver of invasions, metrics of the magnitude of international traded commodities among countries were not related to global distribution patterns. Together, our analyses on the global.scale distribution of this invasive species provide strong evidence for the interplay of biotic and abiotic determinants of spread and also highlight the challenges of limiting the spread and subsequent impact of highly invasive species. [ABSTRACT FROM AUTHOR]

Aim Decision-support models have considerable potential for guiding management strategies when problems are complex. The robustness of such decision-making processes is rarely evaluated, and the influence of decision criteria (or factors) in management decisions is seldom considered. We present a framework for a spatially-explicit sensitivity analysis by using a scheme developed to provide objective guidelines, in the form of static priority maps, for managing woody invasive alien plants (IAPs). Location The Cape Floristic Region, South Africa. Methods The model included seven factors related to management history, fire risk, and the age, identity, density and spread of IAPs. Each factor had a weight associated that reflected its relative importance in prioritizing areas for clearing. We changed these factor weights using three approaches of sensitivity analysis and assessed the effect of these changes on the spatial structure of the resulting priority maps in three different management regions. Results Different outcomes arose depending on the importance given to different factors. Priority maps were most sensitive to the fire-related factors, suggesting that fire is both a crucial driver of invasion in fynbos and an overriding determinant of management options. The factor ‘area burnt recently’ provided crucial information for the effective clearing of IAPs. The sensitivity of the model to changes in other factors was more context specific: levels of sensitivity were highly dependent on different features of the landscape, especially the spatial heterogeneity of particular factors. Main conclusions By clarifying the importance of factors in shaping priority maps, the sensitivity analysis framework enabled us to identify the necessary factors to produce outcomes matching a pre-selected management strategy. This is important for cost-efficient management, as acquisition and curation of data is expensive. This spatially-explicit sensitivity analysis is, thus, recommended to evaluate the robustness and generality of selected management strategies, and validate the assumptions derived from decision-making protocols. [ABSTRACT FROM AUTHOR]

Determining the geographical range of invasive species is an important component of formulating effective management strategies. In the absence of detailed distributional data, species distribution models can provide estimates of an invasion range and increase our understanding of the ecological processes acting at various spatial scales. We used two complementary approaches to evaluate the influence of historical and environmental factors in shaping the distribution of the Argentine ant ( Linepithema humile), a widespread, highly invasive species native to South America. Occurrence data were combined with environmental data at incremental spatial scales (extent and resolution) to predict the suitable range of the ant invasion using ecological niche models. In addition, we also used a spread model that simulated the jump dispersal of the species to identify the most plausible scenarios of arrival of L. humile in the NE Iberian Peninsula at local scales. Based on the results of both modelling practices, we suggest that L. humile might have reached its maximum geographic range at regional scales in the NE Iberian Peninsula. However, the species does not appear in equilibrium with the environment at small spatial scales, and further expansions are expected along coastal and inland localities of the Costa Brava. Long-distance jumps are ultimately responsible for the spread of the Argentine ant in the area. Overall, our study shows the utility of combining niche based models with spread models to understand the dynamics of species' invasions. [ABSTRACT FROM AUTHOR]

Abstract: To address the lack of physiological approaches in current models assessing the potential distribution of the Argentine ant, we used data on brood development from distinct sources to evaluate a series of degree-day models for Catalonia (NE Iberian Peninsula), and data on the brood survival and oviposition rates to develop a worker production model. The degree-day model generated using data from Newell and Barber (1913) and Benois (1973) indicated that the number of degree-days required for the complete development from egg to adult worker was 445.4 degree-days above a threshold of 15.9 °C, while the model calibrated using data from Abril et al. (2008, in press) suggested 599.5 degree-days above 18.4 °C. Comparisons between the degree-day model predictions and the currently known distribution of the Argentine ant suggested that the one generated using data from Newell and Barber (1913) and Benois (1973) overestimated the presence of the species, while the one calibrated using data from Abril et al. (2008; in press) underestimated it. On the other hand, the predicted daily net production of Argentine ant workers generated by the worker production model predicted more accurately the distribution of the Argentine ant than the degree-day models. Our results show the utility of incorporating physiological data in models to assess the distribution limits of the Argentine ant, which up to date have taken little account of the physiological needs of the species in terms of its establishment and dispersion in its introduced ranges. [Copyright &y& Elsevier]

Abstract: Invasive alien trees and shrubs pose significant threats to biodiversity and ecosystem services in South African fynbos ecosystems. An ambitious initiative, the Working for Water program, commenced in 1995 to reduce the extent and impact of plant invasions. Despite substantial progress, the problem remains immense, and innovative ways of improving the efficiency of control operations are urgently needed. This study sought to develop a robust conceptual framework for effective management of the most important invasive alien plant (IAP) species. Two methods were applied in exploring the complexity of problems, thereby identifying appropriate response strategies. The DPSIR (Driving forces-Pressure-State-Impacts-Responses) framework and the Analytic Hierarchy Process (AHP) tool were used to design a strategy for prioritizing management actions. This strategy considers explicitly the most influential factors that determine the distribution, abundance, spread and impacts of IAPs. Efficient management of IAPs is constrained by multiple interacting environmental and socio-economic factors. Factors related to the fire-prone nature of the ecosystem and the characteristics of the invasive stands emerged as pivotal features for setting spatially-explicit priorities for management. Results of the analyses provide an objective and quantifiable perspective for improving the management efficiency. We conclude that considerable progress in controlling the spread of IAPs in fynbos ecosystems could be achieved by better coordination of management practices and by improving the quality of species distribution data. [Copyright &y& Elsevier]

The article presents information on species distributions of insects across spatial scales. It says that extensive researches have been done on this topic, however, relatively less is known about how the determinants of the distributions of single species vary across spatial scales. The author observes that integrating how the elements of niche, distribution and species-habitat association change through time will further improve understanding of the dynamics of distributions of species.

Simple Summary: Discoglossus pictus is a North African amphibian that was introduced in southern France early in the 20th century and has spread south and north along the Mediterranean coastal plains up to 170 km. Many studies have demonstrated that D. pictus competes against native species with similar breeding strategies, pointing out abiotic conditions as the main driver tipping the balance in favor of one or another species. This study aims to assess the impact of the spread of D. pictus on native Iberian Discoglossus and other native species, analyzing the potential roles of long-distance dispersal and long-term climate warming in the Iberian Peninsula. The study area covers the western Mediterranean region, including all Discoglossus species in northwestern Africa, Sicily, the Iberian Peninsula, and southern France. Our results show a strong climatic niche overlap between D. pictus and targeted species in the Iberian Peninsula, including endemic Discoglossus species. Future projections of climatic change suggest that climatic suitability will increase for all species, both inside and outside the Natura 2000 network, with the only exception being a moderate and widespread decrease for Pelodytes punctatus. However, these positive trends are reversed within Natura 2000 sites where most species are explicitly targeted, jeopardizing the effectiveness of protected areas in a long-distance dispersal scenario. Discoglossus pictus is a North African amphibian that was introduced in southern France early the 20th century and has spread south and north along the Mediterranean coastal plains up to 170 km. In order to disentangle the conservation implications of the spread of D. pictus for sensitive native species, we examined the impact of long-term climate warming on the basis of niche overlap analysis, taking into account abiotic factors. The study area covered the distribution ranges of all genus Discoglossus species in northwestern Africa (659,784 km2), Sicily (27,711 km2), the Iberian Peninsula, and southern France (699,546 km2). Niche overlap was measured from species environmental spaces extracted via PCA, including climate and relief environmental variables. Current and future climatic suitability for each species was assessed in an ensemble-forecasting framework of species distribution models, built using contemporary species data and climate predictors and projected to 2070′s climatic conditions. Our results show a strong climatic niche overlap between D. pictus and native and endemic species in the Iberian Peninsula. In this context, all species will experience an increase in climatic suitability over the next decades, with the only exception being Pelodytes punctatus, which could be negatively affected by synergies between global warming and cohabitation with D. pictus. [ABSTRACT FROM AUTHOR]

Species distribution models (SDMs) have been widely applied to predict geographic ranges of species across space and time under the assumption of niche conservatism (i.e., species niches change very slowly). However, an increasing number of studies have reported evidence of rapid niche changes across space and time, which has sparked a widespread debate on whether SDMs can be transferred to new areas or time periods. Understanding how niche changes affect SDM transferability is thus crucial for the future application and improvement of SDMs. Biological invasions provide an opportunity to address this question due to the geographically independent distributions and diverse patterns of niche changes between species' native and introduced ranges. Here, we synthesized findings on 217 species from 50 studies to elucidate the effects of niche change on the spatial transferability of SDMs. When niche change was considered as a categorical classification (conserved vs. shifted niches) in tests of the niche conservatism hypothesis, SDM transferability was markedly lower for species with a shifted niche in their introduced range. When niche change was measured as numerical dynamics between native and introduced niches, SDM transferability was high for species occupying similar environmental conditions in both ranges and low for species with more environmental space remaining unoccupied in the introduced range. Surprisingly, the number of presence points used for developing SDMs turned out to have an even stronger effect on transferability. Our results thus reveal detrimental effects of both niche change and lack of presence points on SDM transferability. It is necessary to consider both niche change and data quality for improving the transferability of SDMs, so that they can better support conservation management and policy decisions. [ABSTRACT FROM AUTHOR]

Determining the potential range of invasive alien species under current conditions is important. However, we also need to consider future distributions under scenarios of climate change and different management interventions when formulating effective long-term intervention strategies. This paper combines niche modelling and fine-scale process-based modelling to define regions at high risk of invasion and simulate likely dynamics at the landscape scale. Our study species is Schinus molle (Peruvian pepper tree; Anacardiaceae), a native of central South America, introduced to South Africa in about 1850 where it was widely planted along roads. Localities of planted and naturalized trees were mapped along 5380 km of roads - a transect that effectively samples a large part of western South Africa. Correlative modelling was used to produce profiles of present and future environmental conditions characterizing its planted and naturalized ranges. A cellular-automata simulation model was used to estimate the dynamics of S. molle under future climates and different management scenarios. The overall potential range of S. molle in the region is predicted to shrink progressively with predicted climate change. Some of the potential range of S. molle defined based on current conditions (including areas where it is currently highly invasive) is likely to become less favourable. The species could persist where it is well established long after conditions for recruitment have deteriorated. Some areas where the species is not widely naturalized now (notably the fynbos biome) are likely to become more favourable. Our modelling approach allows for the delineation of areas likely to be invaded in future by considering a range of factors at different scales that mediate the interplay of climatic variables and other drivers that define the dimensions of human intervention such as distance from planted trees and the density of planted plants, both of which affect propagule pressure. [ABSTRACT FROM AUTHOR]

Biological invasions have emerged as an eminent feature of global change, with substantial impacts on the environment and human livelihoods. Current research demonstrates that the numbers and impacts of alien species are rising unabatedly. At the same time, we lack a thorough understanding of potential future trajectories for the decades to come. With the recent establishment of comprehensive global databases, it is, for the first time, feasible to develop and quantify future scenarios of biological invasions. Therefore, we propose a conceptual framework for how to develop alien species scenarios for the twenty-first century and how to identify relevant steps and challenges along the way. The concept will be important to inform research, policy, stakeholders, and the general public. Furthermore, we call for the scientific community to join forces and to operationalize the framework for scenarios and models of biological invasions to develop an important baseline for understanding and managing future biological invasions. [ABSTRACT FROM AUTHOR]

Aim: Studies of climate change impacts on animal distributions typically consider only the direct impacts of a changing climate, under the assumption that future areas of suitable climate will otherwise remain ecologically suitable. Here we assess both the direct and indirect impacts of climate change on rain forest ant communities, where substantial shifts are projected to occur for both climate and habitat types. Location: Australian Wet Tropics (AWT). Methods: Generalized Dissimilarity Modelling was used to model turnover in the composition of ~300 rain forest ant species sampled at 150 sites across six mountains spanning five degrees of latitude. Ants were sampled within the leaf litter, on the litter surface and on tree trunks. By modelling the rate of turnover among sites, we determined the current effective area of similar ecological environments (SEE) for ant communities and consequently the expected change in species persistence when habitat shifts under two climate projections for the years 2035, 2055 and 2085. We compared results when SEE considered only the direct effects of a changing climate, with those when changes in habitat were also included. Results: The rain forest ant communities modelled will lose a substantial proportion of SEE under both climate change scenarios. Under combined direct (changes in climate) and indirect (changes in rain forest habitat) impacts of climate change, >90% of the communities in the region were predicted to lose up to half their similar habitats compared with 50%–60% when only considering direct climate change impacts. The highest risk of reduction in area of SEE is projected in drier inland areas of the AWT, where profound compositional turnover is linked to dramatic changes in rain forest vegetation, including extensive conversion into savanna. Main conclusions: Our findings emphasize the importance of incorporating habitat suitability into future projections of species turnover under a changing climate, particularly for habitats where vegetation structure is projected to undergo profound change. [ABSTRACT FROM AUTHOR]

Aim: Surrogate species can provide an efficient mechanism for biodiversity conservation if they encompass the needs or indicate the status of a broader set of species. When species that are the focus of ongoing management efforts act as effective surrogates for other species, these incidental surrogacy benefits lead to additional efficiency. Assessing surrogate relationships often relies on grouping species by distributional patterns or by species traits, but there are few approaches for integrating outputs from multiple methods into summaries of surrogate relationships that can inform decision‐making. Location: Prairie Pothole Region of the United States. Methods: We evaluated how well five upland‐nesting waterfowl species that are a focus of management may act as surrogates for other wetland‐dependent birds. We grouped species by their patterns of relative abundance at multiple scales and by different sets of traits, and evaluated whether empirical validation could effectively select among the resulting species groupings. We used an ensemble approach to integrate the different estimated relationships among species and visualized the ensemble as a network diagram. Results: Estimated relationships among species were sensitive to methodological decisions, with qualitatively different relationships arising from different approaches. An ensemble provided an effective tool for integrating across different estimates and highlighted the Sora (Porzana carolina), American Avocet (Recurvirostra Americana) and Black Tern (Chlidonias niger) as the non‐waterfowl species expected to show the strongest incidental surrogacy relationships with the waterfowl that are the focus of ongoing management. Main conclusions: An ensemble approach integrated multiple estimates of surrogate relationship strength among species and allowed for intuitive visualizations within a network. By accounting for methodological uncertainty while providing a simple continuous metric of surrogacy, our approach is amenable to both further validation and integration into decision‐making. [ABSTRACT FROM AUTHOR]

AlienScenarios, a three-year project starting in March 2019, will evaluate for the first time the range of plausible futures of biological invasions for the 21st century. AlienScenarios consists of seven project partners and seven integrated complementary subprojects. We will develop the qualitative narratives for plausible futures of global alien species richness and impacts in the 21st century - the Alien Species Narratives (ASNs). The ASNs further serve as overarching concept to parameterize quantitative models of global, continental and regional futures of biological invasions. We will also establish the first global mechanistic invasion model considering major processes of biological invasions such as source pools, driver dynamics and establishment rates. Further, we will assess the impacts of invasive alien species (IAS) in terms of economic costs according to the different ASNs. In addition, we will assess the consequences of different levels of implementation of the European Union Regulation on IAS. Providing some more detailed regional information, we will analyse changes of the functional composition of communities in mountain regions under different scenario storylines and will extend the analyses to the Global South using Panama as a country-level case study. Finally, the results of the other WPs will be synthesized, and the approach and results of AlienScenarios will be discussed with and communicated to stakeholders and the wider community. AlienScenarios will provide crucially needed insights for pro-active alien species management and policy. It will thus make an important contribution to global assessments and projections of biodiversity and ecosystem services, as well as regional policies (e.g. EU regulation on IAS). [ABSTRACT FROM AUTHOR]

AlienScenarios, a three-year project starting in March 2019, will evaluate for the first time the range of plausible futures of biological invasions for the 21st century. AlienScenarios consists of seven project partners and seven integrated complementary subprojects. We will develop the qualitative narratives for plausible futures of global alien species richness and impacts in the 21st century -- the Alien Species Narratives (ASNs). The ASNs further serve as overarching concept to parameterize quantitative models of global, continental and regional futures of biological invasions. We will also establish the first global mechanistic invasion model considering major processes of biological invasions such as source pools, driver dynamics and establishment rates. Further, we will assess the impacts of invasive alien species (IAS) in terms of economic costs according to the different ASNs. In addition, we will assess the consequences of different levels of implementation of the European Union Regulation on IAS. Providing some more detailed regional information, we will analyse changes of the functional composition of communities in mountain regions under different scenario storylines and will extend the analyses to the Global South using Panama as a country-level case study. Finally, the results of the other WPs will be synthesized, and the approach and results of AlienScenarios will be discussed with and communicated to stakeholders and the wider community. AlienScenarios will provide crucially needed insights for pro-active alien species management and policy. It will thus make an important contribution to global assessments and projections of biodiversity and ecosystem services, as well as regional policies (e.g. EU regulation on IAS). [ABSTRACT FROM AUTHOR]

Aim: The establishment and spread of invasive alien species may be influenced by several mutually interacting factors, whose understanding is paramount to develop effective biosecurity policies. However, studies focused on modelling spatially explicit patterns of future invasion risk have so far focused on species response to climate change impacts, while land‐use change has been neglected. We investigated how the interplay between climate and land‐use change could affect the future potential distribution and dispersal corridors of four alien squirrels introduced to Europe (Sciurus carolinensis,Callosciurus finlaysonii, Callosciurus erythraeus and Eutamias sibiricus). Location and Methods: Our study was conducted in Italy. We used Species Distribution Models and circuit theory methods to test whether future scenarios based only on climate change predict a different effect on range and connectivity of alien squirrel populations, compared to scenarios that include both climate and land‐use changes. Results: Scenarios based only on climate change predicted a range increase and a high geographic stability (>50%) for most species, with different, yet limited, effects on connectivity corridors. Conversely, scenarios based on both climate and land‐use change showed a loss in range extent and a low geographic stability (<50%) of both range and dispersal corridors for most species. Main conclusions: Scenarios considering both climate and land‐use change provide predictions on invasion risk that overturn those including only climate change. The effect of global warming alone would lead to a considerable range expansion of all species. Conversely, when land‐use change is added, a potential loss in suitable habitat and dispersal corridors is predicted for alien squirrels, hence limiting their range expansion. We recommend using multiple drivers in models to obtain reliable predictions for implementing biosecurity policies related to invasive alien species. [ABSTRACT FROM AUTHOR]

Aim: Marked differences in plant and animal responses to climate change could have a profound impact on community composition and function, with implications for habitat structure and resource availability for fauna, and the provision of faunal‐mediated ecological services for flora. We examine the comparative sensitivity of plant and ant assemblages to climatic change, and determine if we should expect community breakdown and a loss of ecosystem function under climate change. Location: A bioclimatic gradient from the temperate to arid zone in South Australia. Methods: We sampled plant and ant assemblages along the gradient to establish assemblage‐level responses to spatial climatic change using ordinations, and then projected assemblage responses to future climate change scenarios. Results: We recorded totals of 363 plant and 227 ant species. Alignment between plant and ant communities was high, suggesting a high degree of similarity in the structuring of plant and ant communities in relation to environmental variation. However, our modelling suggested that ant assemblages were up to 7.5 times more sensitive to projected climate change than were plant assemblages, forecasting a very substantial decoupling of these assemblages under a future climate. Main conclusions: Our results indicate that a high degree of community reorganization and change in ecosystem function should be expected under climate change. [ABSTRACT FROM AUTHOR]

Aim Stochastic threats such as disease outbreak, pollution events, fire, tsunami and drought can cause rapid species extinction and ecosystem collapse. The ability of a species or ecosystem to persist after a stochastic threat is strongly related to the extent and spatial pattern of its geographical distribution. Consequently, protocols for assessing risks to biodiversity typically include geographic range size criteria for assessing risks from stochastic threats. However, owing in part to the rarity of such events in nature, the metrics for assessing risk categories have never been tested. In this study, we investigate the performance of alternative range size metrics, including the two most widely used, extent of occurrence ( EOO) and area of occupancy ( AOO), as predictors of ecosystem collapse in landscapes subject to stochastic threats. Methods We developed a spatially explicit stochastic simulation model to investigate the impacts of four threat types on a dataset of 1350 simulated geographic distributions of varying pattern and size. We empirically estimated collapse probability in response to each threat type and evaluated the ability of a set of spatial predictors to predict risk. Results The probability of ecosystem collapse increased rapidly as range size declined. While AOO and EOO were the most important predictors of collapse risk for the three spatially explicit threats included in our model (circle, swipe and cluster), core area, patch density and mean patch size were better predictors for edge effect threats. Main conclusions Our study is the first to quantitatively assess the range size metrics employed in biodiversity risk assessment protocols. We show that the current methods for measuring range size are the best spatial metrics for estimating risks from stochastic threats. Our simulation framework delivers an objective assessment of the performance of hitherto untested but widely used measures of geographic range size for risk assessment. [ABSTRACT FROM AUTHOR]

Aim To investigate whether feral cats influence the distribution of Australia's largest remnant population of the threatened brush-tailed rabbit-rat Conilurus penicillatus and examine whether they influenced the extinction probability of C. penicillatus over a 15-year period (2000-2015). Location Melville Island, northern Australia. Methods In 2015, small mammal surveys were conducted at 88 sites across Melville Island, 86 of which had previously been surveyed in 2000-2002. We used single-season occupancy models to investigate correlates of the current distribution of C. penicillatus and dynamic occupancy models to investigate correlates of C. penicillatus local extinction. Results Our results show that C. penicillatus, which once occurred more widely across the island, is now restricted to parts of the island where feral cats are rarely detected and shrub density is high. Our results suggest that feral cats are driving C. penicillatus towards extinction on Melville Island, and hence have likely been a significant driver in the decline of this species in northern Australia more broadly. The impact of feral cats appears to be mitigated by vegetation structure. Main conclusions The ongoing development and implementation of methods to effectively reduce feral cat densities, coupled with the management of landscape processes to maintain shrub density, through fire management and the removal of large exotic herbivores, will contribute substantially to conserving this threatened species. This study demonstrates that the distribution of species can be strongly influenced by top-down factors such as predation, thereby highlighting the importance of including biotic interactions when investigating the distribution of predation-susceptible species. [ABSTRACT FROM AUTHOR]

Aims Effective conservation of threatened or endangered species requires a robust understanding of their spatio-temporal distribution. Although a huge amount is known about the movements of Atlantic adult sea turtles, much less is known about juvenile turtles, and much of the life history model is therefore inferred. We set out to describe the spatio-temporal distribution of juvenile loggerheads turtles found around the Canary Islands. Location Eastern North Atlantic Ocean. Methods Between 1999 and 2012, we satellite-tracked 24 healthy large juvenile loggerhead turtles (mean straight carapace length = 47.4 cm, range = 34.6-54.5 cm) captured in the waters around the Canary Islands. We describe their regional distribution, identify high-use areas and create a model for habitat suitability using minimum convex polygons, density rasters and ensemble ecological niche modelling, integrated with physical and biological environmental data. Results Turtles used a huge oceanic area (2.5 million km2) with particularly high usage around the Canary Islands, Spain, Portugal, Morocco and Western Sahara. In spring and summer, turtles generally moved further north towards the Iberian Peninsula. Ecological niche modelling identified sea surface temperature as the most important contributory variable to the habitat models. We also recorded three juvenile turtles making westward migrations away from the eastern Atlantic Ocean, presumably back towards their original natal beaches near sexual maturity. Main conclusions The results of the present study provide insight into a significant knowledge gap on the spatio-temporal distribution of large juvenile loggerhead turtles in the eastern Atlantic Ocean. The data highlight that turtles occupy a vast open oceanic area, which hampers the ability of static conservation approaches to afford effective protection. However, ensemble ecological niche modelling highlights key suitable habitat for juvenile loggerhead turtles, which could be used in dynamic conservation protection. [ABSTRACT FROM AUTHOR]

Aim Species' distributions are generally treated as static for the purposes of prioritization, but many species such as migrants and nomads have distributions that shift over time. Decisions about priority actions for such species must account for this temporal variation, making planning for their conservation a complex problem. Here, we explore how dynamic distributions can be incorporated into a spatial prioritization, and suggest approaches for prioritizing conservation action when knowledge of species' movements is uncertain. Location Australian rangelands, including the arid and semi-arid zones of central Australia and adjoining monsoonal tropics, although methods are applicable for any dynamic biodiversity feature. Methods We used the decision-support software marxan to explore the impact of temporal dynamics on spatial conservation planning for a suite of 42 highly mobile birds across the study region. We explored scenarios comparing a static representation of species' distributions with four methods of integrating temporal dynamics: (1) accounting for temporal variability in distribution across months and years, (2) considering only monthly variability in distribution, (3) considering only annual variability in distribution and (4) considering only minimal distributions during spatial bottlenecks, ignoring distributions at other times. Results Incorporating the temporal dynamics of species into spatial prioritization substantially changes the spatial pattern of conservation investment, increasing the overall area needed to be placed under conservation measures to achieve a specific target level of species protection. Targeting bottlenecks, locations critical to each species when its distribution is at a minimum, prioritizes a very different suite of sites to those chosen using the traditional approach of static distribution maps based on occurrences pooled across time. Main conclusions Our results highlight the need to consider dynamic movements in the conservation planning process to ensure that mobile species are adequately protected. A static approach to conservation planning may misdirect resources and lead to inadequate conservation for mobile species. [ABSTRACT FROM AUTHOR]

Peer assessment provides students with multiple benefits during their learning process. The aim of our study is to examine students’ perception of peer assessment. Questionnaires were administered before and after the peer-assessment process to 416 students studying 11 different subjects in four different fields taught at the University of Girona. Results suggest that students have a positive predisposition towards this methodology, both before and after its implementation. Students perceive it as a both motivating and recommended methodology that facilitates the acquisition of learning at different levels. As for its limitations, students highlight the responsibility that comes with it and a certain amount of distrust in fellow students’ abilities to peer-assess. [ABSTRACT FROM PUBLISHER]

Aim: Understanding the role of enemy release in biological invasions requires an assessment of the invader's home range, the number of invasion events and enemy prevalence. The common wasp (Vespula vulgaris) is a widespread invader. We sought to determine the Eurasian origin of this wasp and examined world-wide populations for microsporidian pathogen infections to investigate enemy release. Location: Argentina, Eurasia, New Zealand. Methods: A haplotype network and phylogenetic tree were constructed from combined wasp COI and cytb mitochondrial markers. A morphometric study using canonical discriminant analysis was conducted on wing venation patterns. Microsporidian pathogens prevalence was also examined using small subunit rRNA microsporidia-specific primers. Results: Our spatially structured haplotype network from the native range suggested a longitudinal cline of wasp haplotypes along an east to west gradient. Six haplotypes were detected from New Zealand, and two from Argentina. The populations from the introduced range were genetically similar to the western European, United Kingdom and Ireland. The morphometric analysis showed significant morphological variation between countries and supported the Western European origin for New Zealand populations, although not for Argentine samples. Microsporidian infection rates were highest in New Zealand samples (54%), but no significant differences in infection rates were observed between the invaded and native range. Nosema species included matches to N. apis (a pathogen from honey bees) and N. bombi (from bumble bees). Main conclusions: Multiple introductions of the common wasp have occurred in the invaded range. A high microsporidian infection rate within the native range, combined with multiple introductions and a reservoir of pathogens in other social insects such as bees, likely contributes to the high microsporidian infection rates in the invaded range. Enemy release is likely to be more frequent when pathogens are rare in the home range, or are host specific and rare in reservoir populations of the introduced range. [ABSTRACT FROM AUTHOR]

Aim Understanding the conditions that promote biological invasions is a critical step to developing successful management strategies. However, the level of invasion is affected by complex interactions among environmental factors that might change across habitats and regions making broad generalizations uninformative for management. We aimed to quantify the context-dependent association of climate and human activity at landscape scale (i.e. disturbance and propagule pressure) with the level of plant invasion at local scale across different stages of invasion, habitat types and bioclimatic regions. Location Mainland Spain. Methods Based on an extensive database of vegetation plots (~50,000), we used hierarchical Bayesian models to test how climate and human activity at a landscape scale (i.e. land-cover variables) are associated with establishment (i.e. presence) and dominance (i.e. relative species richness and abundance in invaded plots) of non-native plants across nine habitat types and three bioclimatic regions. Results The association of climate with establishment and dominance of non-native plants varied depending on habitat type but not bioclimatic region. These associations also varied depending on the stage of invasion under consideration. Establishment of non-native species was more likely close to the coast, while their dominance increased in wet and warm continental areas. Human activity variables were associated with establishment and dominance similarly across bioclimatic regions. Non-native species establishment and abundance peaked in human-altered landscapes. Different habitats showed different susceptibilities to establishment versus dominance by non-native species (e.g. woodlands had medium levels of establishment, but very low dominance). Main conclusions This study highlights how complex interactions among climate, human activity and habitats can determine patterns of invasions across broad landscapes. Successful management of plant invasions will depend on understanding these context-dependent effects across habitats at the different stages of the invasion process. [ABSTRACT FROM AUTHOR]

Aim Habitat selection is a behavioural mechanism by which animals attempt to maximize their inclusive fitness while balancing competing demands, such as finding food and rearing offspring while avoiding predation, in a heterogeneous and changing environment. Different habitat characteristics may be associated with each of these demands, implying that habitat selection varies depending on the behavioural motivations of the animal. Here, we investigate behaviour-specific habitat selection in African elephants and discuss its implications for distribution modelling and conservation. Location Northern Botswana, Africa, case study. Methods We use Bayesian state-space models to characterize location time series data of elephants into two behavioural states (encamped and exploratory). We then develop habitat selection models for each behavioural state and contrast them to models based on data pooled among behaviours. Results Spatial predictions of habitat use were often markedly different among the models. Behaviour-specific and pooled habitat selection models differed in model structure, the magnitude of model coefficients and the form of the selection curve (linear or quadratic). Selection was typically strongest in the behaviour-specific models, although this varied according to behavioural state and habitat covariate. Main conclusions Ignoring behavioural states often had important consequences for quantifying habitat selection. Quantifying selection irrespective of behaviour (among all behaviours) can obscure important species-habitat relationships, thereby risking weak or incorrect inferences. Behaviour-specific habitat selection provides greater insight into the process of habitat selection and can improve predictive habitat selection estimates. As some behaviours are more relevant to specific conservation objectives than others, focusing on behaviour-specific selection could improve how habitats are prioritized for conservation or management. [ABSTRACT FROM AUTHOR]

Aim Global conservation planning is often oriented around vertebrates and plants, yet most organisms are invertebrates. To explore the potential conservation implications of this bias, we assessed how well patterns of diversity for an influential group of invertebrates, the ants, correspond with those of three vertebrate groups (birds, mammals and amphibians). Location Global. Methods We compiled data on the number of genera of ants and the three vertebrate groups for 370 political regions across the world. We then compared their correlations both for overall diversity and between subsets of genera likely to be of conservation concern. We also developed generalized additive models (GAM) to identify regions where vertebrates and ants diverged in their diversity patterns. Results While ant and vertebrate diversity do positively correlate, the correlations are substantially weaker for the ant lineages of the greatest conservation concern. Vertebrates also notably fail to predict ant diversity in specific geographic areas, including Australia and Southeast Asia, parts of Africa and Madagascar, and south-western China. These failures may be genuine differences in diversity patterns, or they may indicate important gaps in our knowledge of ant and vertebrate diversity. Main conclusions We conclude that it is currently unwise to assume that global conservation priorities based on vertebrates will conserve ants as well. We suspect that this also applies to other invertebrates. [ABSTRACT FROM AUTHOR]

Refugee species have been confined to suboptimal habitat through historic anthropogenic factors. If this is unknown, management might actively conserve these species in suboptimal habitat assuming it represents optimal habitat. Similarly, species distribution modelling ( SDM) might misguide conservation management of refugee species by only using presence data from suboptimal habitats. We illustrate this by commenting on a recent SDM for European bison that reconstructed the historic distribution of the species. We challenge the interpretation of this model by suggesting an alternative historic biogeography based on the refugee species concept. We argue that, in the case of refugee species, historic reconstructions using SDM cannot be used as a template for conservation management. Rather, experimental re-introduction programmes should provide us with population performance and life history data from a range of suboptimal to optimal habitats. Such data could be used in mechanistic niche modelling to predict potential distribution of refugee species. [ABSTRACT FROM AUTHOR]

Understanding species' historical ranges can provide important information for conservation planning in the face of environmental change. Cromsigt et al. (this issue) comment on our recent European bison ( Bison bonasus) range reconstruction, suggesting that bison were already 8000 years ago a refugee species (i.e. restricted to marginal habitat due to past human pressure) and that species distribution models ( SDM) are generally of limited use for refugee species conservation. While we welcome this discussion, we find no evidence for the claim that human pressure prior to 8000 BP determined where bison occurred. More importantly, as human pressure is generally high and increasing, attempts to restore species across their former range may fail where the factors that relegated species into refugee status are still at play or where their optimal habitat has vanished. Identifying areas where human pressure is low and where refugee species have persisted over the last millennia is crucial, and SDM based on historical data are important for doing so. Refugee species suffer from the shifting baseline syndrome, but careful reality checks are needed and all available data should be considered before determining the baseline that should inform conservation planning. [ABSTRACT FROM AUTHOR]

The cover image, by Lucy Hawkes et al., is based on the Biodiversity Research New findings about the spatial and temporal use of the Eastern Atlantic Ocean by large juvenile loggerhead turtles, DOI:10.1111/ddi.12413. Photo Credit:SECAC / Nuria Varo Cruz. [ABSTRACT FROM AUTHOR]