Invasive alien species are one of the major threats to global biodiversity, ecosystem integrity, nature's contributions 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 the future across spatial scales. Based on previous work on global invasion scenarios, we developed a workflow to downscale global scenarios to a regional and policy‐relevant context. We applied this workflow at the European scale to create four European scenarios of biological invasions until 2050 that consider different environmental, socio‐economic and socio‐cultural trajectories, namely the European Alien Species Narratives (Eur‐ASNs). We compared the Eur‐ASNs with their previously published global counterparts (Global‐ASNs), assessing changes in 26 scenario variables. This assessment showed a high consistency between global and European scenarios in the logic and assumptions of the scenario variables. However, several discrepancies in scenario variable trends were detected that could be attributed to scale differences. This suggests that the workflow is able to capture scale‐dependent differences across scenarios. We also compared the Global‐ and Eur‐ASNs with the widely used Global and European Shared Socioeconomic Pathways (SSPs), a set of scenarios developed in the context of climate change to capture different future socio‐economic trends. Our comparison showed considerable divergences in the scenario space occupied by the different scenarios, with overall larger differences between the ASNs and SSPs than across scales (global vs. European) within the scenario initiatives. Given the differences between the ASNs and SSPs, it seems that the SSPs do not adequately capture the scenario space relevant to understanding the complex future of biological invasions. This underlines the importance of developing independent but complementary scenarios focussed on biological invasions. The downscaling workflow we implemented and presented here provides a tool to develop such scenarios across different regions and contexts. This is a major step towards an improved understanding of all major drivers of global change, including biological invasions. Read the free Plain Language Summary for this article on the Journal blog.
West Nile virus (WNV) is a globally significant vector-borne disease that is primarily transmitted between birds and mosquitoes. Recently, there has been an increase in WNV in southern Europe, with new cases reported in more northern regions. Bird migration plays a crucial role in the introduction of WNV in distant areas. To better understand and address this complex issue, we adopted a One Health approach, integrating clinical, zoological, and ecological data. We analyzed the role of migratory birds in the Palaearctic-African region in the spread of WNV across Africa and Europe. We categorized bird species into breeding and wintering chorotypes based on their distribution during the breeding season in the Western Palaearctic and the wintering season in the Afrotropical region, respectively. By linking these chorotypes to the occurrence of WNV outbreaks in both continents throughout the annual bird migration cycle, we investigated the relationship between migratory patterns and virus spread. We demonstrate that WNV-risk areas are interconnected through the migration of birds. We identified a total of 61 species that potentially contribute to the intercontinental spread of the virus or its variants, as well as pinpointed high-risk areas for future outbreaks. This interdisciplinary approach, which considers the interconnectedness of animals, humans, and ecosystems, represents a pioneering effort to establish connections between zoonotic diseases across continents. The findings of our study can aid in anticipating the arrival of new WNV strains and predicting the occurrence of other re-emerging diseases. By incorporating various disciplines, we can enhance our understanding of these complex dynamics and provide valuable insights for proactive and comprehensive disease management strategies.
Ongoing global change makes it ever more urgent to find creative solutions for biodiversity preservation, but prioritizing sites for protection can be challenging. One shortcut lies in mapping the habitat requirements of well-established biodiversity indicators, such as top predators, to identify high-biodiversity sites. Here, we planned site protection for biodiversity conservation by developing a multi-scale species distribution model (SDM) for the raptorial Northern Goshawk (Accipiter gentilis; goshawk) breeding in an extensive megacity region of Japan. Specifically, we: (1) examined the determinants of top predator occurrence and thus of high-biodiversity value in this megacity setting, (2) identified the biodiversity hotspots, (3) validated whether they actually held higher biodiversity through an independent dataset, and (4) evaluated their current protection by environmental laws. The SDM revealed that goshawks preferred secluded sites far from roads, with abundant forest within a 100 m radius and extensive forest ecotones suitable for hunting within a 900 m radius. This multi-scale landscape configuration was independently confirmed to hold higher biodiversity, yet covered only 3.2% of the study area, with only 44.0% of these sites legally protected. Thus, a rapid biodiversity assessment mediated by a top predator quickly highlighted: (1) the poor development of biodiversity-friendly urban planning in this megacity complex, an aspect overlooked for decades of rapid urban sprawl, and (2) the extreme urgency of extending legal protection to the sites missed by the current protected area network. Exigent biodiversity indicators, such as top predators, could be employed in the early or late stages of anthropogenic impacts in order to proactively incorporate biodiversity protection into planning or flag key biodiversity relics. Our results confirm and validate the applied reliability of top predatory species as biodiversity conservation tools.
Ecologists have long documented that the world's biota is spatially organised in regions with boundaries shaped by processes acting on geological and evolutionary timescales. Although growing evidence suggests that historical human impact has been key in how biodiversity is currently assembled, its role as a driver of the geographical organisation of biodiversity remains unclear. Using non‐volant terrestrial mammals we set up a bioregionalization procedure focused on two datasets, one describing the current ranges of terrestrial mammals, and another describing their potential natural ranges in absence of historic anthropogenic land use. We then quantified the relative importance of anthropogenic land use (5000 and 2000 years ago, and present time) to predict the current and natural biogeographical regions across the Earth. In general, past and present human land use were important predictors of current bioregions but did not largely contribute to predict natural bioregions. Past anthropogenic land use seems to have left an imprint on the taxonomic differentiation of some of the largest biogeographical realms, whereas land use at present stands out as a driver of the taxonomic differences between medium‐sized subregions, i.e. within and among continents. Our findings suggest that anthropogenic actions during the last millennia have had a far‐reaching effect on the spatial organisation of the Earth's non‐volant mammals.
The rapid conversion of natural habitats to anthropogenic landscapes is threatening insect pollinators worldwide, raising concern regarding the negative consequences on their fundamental role as plant pollinators. However, not all pollinators are negatively affected by habitat conversion, as certain species find appropriate resources in anthropogenic landscapes to persist and proliferate. The reason why some species tolerate anthropogenic environments while most find them inhospitable remains poorly understood. The cognitive buffer hypothesis, widely supported in vertebrates but untested in insects, offers a potential explanation. This theory suggests that species with larger brains have enhanced behavioural plasticity, enabling them to confront and adapt to novel challenges. To investigate this hypothesis in insects, we measured brain size for 89 bee species, and evaluated their association with the degree of habitat occupancy. Our analyses revealed that bee species mainly found in urban habitats had larger brains relative to their body size than those that tend to occur in forested or agricultural habitats. Additionally, urban bees exhibited larger body sizes and, consequently, larger absolute brain sizes. Our results provide the first empirical support for the cognitive buffer hypothesis in invertebrates, suggesting that a large brain in bees could confer behavioural advantages to tolerate urban environments.
We evaluate the frequency of flipper amputation and its impact on reproduction in the threatened loggerhead turtle (Caretta caretta) population of the Eastern Atlantic , through a long-term study on several high-density nesting beaches of Cabo Verde. 5982 adult females were individually identified, tagged and measured, and the presence of limb amputations was recorded. 918 of them had one or multiple amputations of the rear or front flippers. Most of these turtles (n = 778) had partial rather than complete flipper amputations. However, we found no difference in body condition indices (1.2 vs. 1.1), clutch size (82 vs. 83 eggs), or hatching success (79 vs. 80%) between amputated and non-amputated females. While amputations may cause individual mortality or reduced fitness, our results indicate that some amputated turtles successfully nest and survive across multiple nesting seasons. Moreover, the amputations do not appear to be impacting the strong recovery of this population. This study provides evidence of the successful reproductive capacity of amputated loggerhead sea turtles and, by extension, the potential reproductive success of amputees released from recovery centers.
Understanding the drivers and consequences of global environmental change is crucial to inform predictions of effects on ecosystems. We used the mammal community of Białowieża Forest, the last lowland near‐primeval forest in temperate Europe, as a sentinel of global change. We analyzed changes in stable carbon (δ ¹³ C) and nitrogen (δ ¹⁵ N) isotope values of hair in 687 specimens from 50 mammal species across seven decades (1946–2011). We classified mammals into four taxonomic‐dietary groups (herbivores, carnivores, insectivores, and bats). We found a significant negative trend in hair δ ¹⁵ N for the mammal community, particularly strong for herbivores. This trend is consistent with temporal patterns in nitrogen deposition from ( ¹⁵ N depleted) industrial fertilizers and fossil fuel emissions. It is also in line with global‐scale declines in δ ¹⁵ N reported in forests and other unfertilized, non‐urban terrestrial ecosystems and with local decreases in N foliar concentrations. The global depletion of ¹³ C content in atmospheric CO 2 due to fossil fuel burning (Suess effect) was detected in all groups. After correcting for this effect, the hair δ ¹³ C trend became non‐significant for both community and groups, except for bats, which showed a strong decline in δ ¹³ C. This could be related to an increase in the relative abundance of freshwater insects taken by bats or increased use of methane‐derived carbon in food webs used by bats. This work is the first broad‐scale and long‐term mammal isotope ecology study in a near‐primeval forest in temperate Europe. Mammal communities from natural forests represent a unique benchmark in global change research; investigating their isotopic temporal variation can help identify patterns and early detections of ecosystem changes and provide more comprehensive and integrative assessments than single species approaches.
Freshwater ecosystems are invaded by a non‐random selection of taxa, among which crayfish stand out with successful examples worldwide. Species distribution models (SDMs) have been used to detect suitable areas for invasive species and predict their potential distributions. However, these prediction exercises assume the stability of realized environmental niches, which is uncertain during invasion. Worldwide evaluations involving cosmopolitan invaders may be particularly useful but have seldom been considered. Focusing on the successful invasion history of the red swamp crayfish, Procambarus clarkii , we assessed its geographic expansion and niche trends over time. Based on global occurrences from 1854 to 2022, multiple sequential SDMs have been implemented based on a set of bioclimatic variables. The environmental suitability for each period was projected through to the next period(s) using an ensemble procedure of commonly used SDM algorithms. As the records of the species are known, it was possible to check whether the modelling projections were concordant with the observed expansion of red swamp crayfish at a global scale. This also permitted analysis of its realized niche, and its dynamics, during different expansion phases. SDM maps based on past species records showed concordance with the known crayfish distributions and yielded similar spatial patterns with outputs overperforming random combinations of cells in term of suitability. The results also reflect the stability of the species niche, which despite some expansions during the invasion process, changed little in terms of main position in functional space over time. SDMs developed in the early stages of invasion provide useful insights but also tend to underpredict the potential range compared to models that were built for later stages. Our approach can be easily transferable to other well‐documented taxa and represents valuable evidence for validating the use of SDMs, considering a highly dynamic world where biogeographical barriers are often bypassed.
Biological invasions are a major threat to Australia. Information on alien flora in Australia is collated independently by different jurisdictions, which has led to inconsistencies at the national level, hampering efficient management. To harmonise different information sources, we present the Alien Flora of Australia (AFA), a nationally unified dataset. To create the AFA, we developed an R script that compares existing data sources (the Australian Plant Census and state and territory censuses), identifies mismatches among them and integrates the information into unified invasion statuses at the national scale. The AFA follows the taxonomy and nomenclature adopted for the Australian Plant Census, introduction status and impact of plants known to occur in Australia. The up-to-date information presented in this dataset can aid early warning of alien species invasions, facilitate decision-making at different levels, and biosecurity at national scale. The associated script is ready to be implemented into new versions of the AFA with updated releases of any of the data sources, streamlining future efforts to track of alien flora across Australia.
Ducks and geese are little studied dispersal vectors for plants lacking a fleshy fruit, and our understanding of the traits associated with these plants is limited. We analyzed 507 faecal samples of mallard ( Anas platyrhynchos ) and Canada goose ( Branta canadensis ) from 18 natural and urban wetlands in England, where they are the dominant resident waterfowl. We recovered 930 plant diaspores from 39 taxa representing 18 families, including 28 terrestrial and five aquatic species and four aliens. Mallards had more seeds and seed species per sample than geese, more seeds from barochory and hydrochory syndromes, and seeds that on average were larger and from plants with greater moisture requirements (i.e., more aquatic). Mallards dispersed more plant species than geese in natural habitats. Plant communities and traits dispersed were different between urban (e.g., more achenes) and natural (e.g., more capsules) habitats. Waterfowl can readily spread alien species from urban into natural environments but also allow native terrestrial and aquatic plants to disperse in response to climate heating or other global change. Throughout the temperate regions of the Northern Hemisphere, the mallard is accompanied by a goose (either the Canada goose or the greylag goose) as the most abundant waterfowl in urbanized areas. This combination provides a previously overlooked seed dispersal service for plants with diverse traits.
Shrubs are key components of temperate and boreal ecosystems. Field experiments performed along environmental gradients are useful to study how these species may cope with new climatic conditions. We analyzed the effects of habitat, elevation, and canopy on the performance of the bilberry Vaccinium myrtillus, a key resource for numerous species in boreal and temperate regions of Eurasia. We estimated bilberry dry mass and measured vegetative (ramet height, stem diameter, and shoot production) and reproductive (fruit and seed production) performance of bilberry shrubs in thirty plots located at six study sites established in coniferous forests and subalpine meadows along a 600-m elevation gradient in Tatra National Park, Poland. Although we detected more ramets per plot in the meadows, bilberry dry mass was larger inside the forest, whereas ramets were heavier and taller and produced more annual shoots. A higher proportion of ramets produced fruits in the meadows, where we additionally found a higher proportion of mature seeds per bilberry fruit. When only plots located inside the forest were considered, we detected a negative relation between elevation and bilberry ramet dry mass. Canopy cover affected the number of ramets and the dry bilberry biomass per plot differently depending on the elevation, demonstrating interactive effects of these two variables in bilberry vegetative performance. Fruit production inside the forest was negatively affected by both elevation and canopy cover, while interactive effects of these two variables determined seed development. Bilberry management actions must consider habitat heterogeneity even at small spatial scales and possible interactive effects of environmental variables such as those analyzed in this study.
Delineating spatial boundaries that accurately encompass complex, often cryptic, life histories of highly migratory marine megafauna can be a significant conservation challenge. For example, marine turtles range across vast ocean basins and coastal areas, thus complicating the evaluation of relative impacts of multiple overlapping threats and the creation of coherent conservation strategies. To address these challenges, spatially explicit ‘regional management units’ (RMUs) were developed in 2010 for all marine turtle species, globally. RMUs were intended to provide a consistent framework that organizes conspecific assemblages into units above the level of nesting rookeries and genetic stocks, but below the species level, within regional entities that may share demographic trajectories because they experience similar environmental conditions and other factors. From their initial conception, RMUs were intended to be periodically revised using new information about marine turtle distributions, life history, habitat use patterns, and population structure. Here, we describe the process used to update the 2010 RMU framework by incorporating newly published information and inputs from global marine turtle experts who are members of the IUCN Marine Turtle Specialist Group. A total of 48 RMUs for 6 of 7 marine turtle species and 166 distinct genetic stocks for all 7 species are presented herein. The updated RMU framework reflects a significant advance in knowledge of marine turtle biology and biogeography, and it provides improved clarity about the RMU concept and its potential applications. All RMU products have been made open access to support research and conservation initiatives worldwide.
Protecting aquatic ecosystems requires comprehensive understanding and quantification of threats posed by invasive species to inform effective management strategy. In particular, aquatic invasive plants cause profound alterations to aquatic ecosystem composition, structure and productivity, however, monetary cost assessments have lacked at large scales. Here, for the first time, we synthesize the global economic impacts of aquatic and semi-aquatic invasive plants to describe the distributions of these costs across taxa, habitat types, environments, impacted sectors, cost typologies and geographic regions. We also examine the development of recorded costs over time across linear and non-linear models and infer the geographical gaps of recorded costs by superimposing cost and species distribution data. Between 1975 and 2020, the total cost of aquatic and semi-aquatic invasive plants to the global economy exceeded US$ 32 billion, of which the majority of recorded costs (57%) was attributable to multiple or unspecified taxa. Submerged plants had $8.4 billion (25.5 %) followed by floating plants $4.7 billion (14.5%), emergent $684 million (2.1%) and semi-aquatic $306 million (0.9%). Recorded costs were disproportionately high towards freshwater ecosystems, which have received the greatest cost research effort compared to marine and brackish systems. Public and social welfare and fisheries were the sectors most affected, while agriculture and health were most underreported. Cost attributed to management (4.8%; $1.6 billion) represented only a fraction of damages (85.8%; $28.2 billion). While recorded costs are rising over time, reporting issues e.g., robustness of data, lack of higher taxonomic resolution and geographical gaps (costly taxa currently occupying regions where monetary cost reports are lacking despite well-known impacts) likely have led to a dampening of trajectories. More robust and timely cost estimates will enhance interpretation of current and future impacts of aquatic invasive plants, assisting the long-term sustainability of our aquatic ecosystems and associated economic activities.
ARTICLE Ongoing harlequin toad declines suggest the amphibian extinction crisis is still an emergency Biodiversity loss is extreme in amphibians. Despite ongoing conservation action, it is difficult to determine where we stand in overcoming their extinction crisis. Among the most threatened amphibians are the 131 Neotropical harlequin toads. Many of them declined since the 1980s with several considered possibly extinct. Recently, more than 30 species have been rediscovered, raising hope for a reversing trend in the amphibian extinction crisis. We use past and present data available for harlequin toads (Atelopus), to examine whether the amphibian extinction crisis is still in an emergency state. Since 2004 no species has improved its population status, suggesting that recovery efforts have not been successful. Threats include habitat change, pathogen spread and climate change. More mitigation strategies need implementation, especially habitat protection and disease management, combined with captive conservation breeding. With harlequin toads serving as a model, it is clear that the amphibian extinction crisis is still underway.
The gray wolf (Canis lupus) population on the Iberian Peninsula was the largest in western and central Europe during most of the 20th century, with its size apparently never under a few hundred individuals. After partial legal protection in the 1970s in Spain, the northwest Iberian population increased to about 300-350 packs and then stabilized. In contrast to many current European wolf populations, which have been connected through gene flow, the Iberian wolf population has been isolated for decades. Here we measured changes on genomic diversity and inbreeding through the last decades in a geographic context. We find that the level of genomic diversity in Iberian wolves is low compared to other Eurasian wolf populations. Despite population expansion in the last 50 years, some modern wolves had very high inbreeding, especially in the recently recolonized and historical edge areas. These individuals contrast with others with low inbreeding within the same population. The high variance in inbreeding despite population expansion seems associated with small-scale fragmentation of the range that is revealed by the genetic similarity between modern and historical samples from close localities despite being separated by decades, remaining differentiated from other individuals that are just over 100 km away, a small distance for a species with great dispersal capacity inhabiting a continuous range. This illustrates that, despite its demographically stable condition, the population would probably benefit from favoring connectivity within the population as well as genetic exchange with other European wolf populations to avoid excessive fragmentation and local inbreeding depression.
Recent research has confirmed the efficiency of insectivorous bats as pest suppressors, underlining the ecological services they offer in agroecosystems. Therefore, some efforts try to enhance bat foraging in agricultural landscapes by acting upon environmental factors favouring them. In this study, we monitored a Miniopterus schreibersii colony in the southern Iberian Peninsula. We intensively sampled their faeces and analysed them by metabarcoding to describe how the bent-winged bat diet would change with time, and to test whether their most-consumed prey would seasonally depend on different landscapes or habitats. Our results confirm that M. schreibersii are selective opportunist predators of moths, dipterans, mayflies, and other fluttering insects, shifting their diet to temporary peaks of prey availability in their foraging range, including both pest and non-pest insects. Supporting our hypothesis, throughout the year, M. schreibersii consume insects linked to diverse open habitats, including wetlands, grassland, diverse croplands, and woodland. The importance of each prey habitat varies seasonally, depending on their insect phenology, making bats indirectly dependent on a diverse landscape as their primary prey source. Bats’ predation upon pest insects is quantitatively high, consuming around 1610 kg in 5 months, of which 1467 kg correspond to ten species. So, their suppression effect may be relevant, mainly in patchy heterogeneous landscapes, where bats’ foraging may concentrate in successive outbursts of pests, affecting different crops or woodlands. Our results stress that to take advantage of the ecosystem services of bats or other generalist insectivores, keeping the environmental conditions they require to thrive, particularly a heterogeneous landscape within the colony’s foraging area, is crucial.
Interactions between plants and herbivores are central in most ecosystems, but their strength is highly variable. The amount of variability within a system is thought to influence most aspects of plant-herbivore biology, from ecological stability to plant defense evolution. Our understanding of what influences variability, however, is limited by sparse data. We collected standardized surveys of herbivory for 503 plant species at 790 sites across 116° of latitude. With these data, we show that within-population variability in herbivory increases with latitude, decreases with plant size, and is phylogenetically structured. Differences in the magnitude of variability are thus central to how plant-herbivore biology varies across macroscale gradients. We argue that increased focus on interaction variability will advance understanding of patterns of life on Earth.
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