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Invasive species are considered a major threat to ecosystem functioning and native biodiversity. Their negative impacts on ecosystems and the provisioning of ecosystem services have been widely documented. South Africa faces one of the most significant challenges from invasive species globally, and the South African government spent an estimated US $100 million to mitigate impacts of non‐native species between 1995 and 2000 alone. Here, we modeled the current climatic niche of 162 non‐native trees and shrubs within South Africa and explored potential shifts in their distribution with projected climate change. Our results indicate that over half of these species will experience a decrease in their suitable climate over the next decades, although not uniformly so and ranges are predicted to expand into some regions. We also compared recent vs. historical introductions and showed similar patterns, indicating that possible violation of equilibrium assumptions in our distribution models likely does not strongly influence our findings. We suggest that climate change may therefore provide a window of opportunity for more effective invasive species control within South Africa, but that large range shifts are likely for many non‐natives in the future, and new invasive threats might emerge.

Biological invasions are increasing worldwide, damaging ecosystems and socioeconomic sectors. Two decades ago, the “100 of the world’s worst” invasive alien species list was established by the IUCN to improve communications , identifying particularly damaging ‘flagship’ invaders globally (hereafter, worst). Whilst this list has bolstered invader awareness, whether worst species are especially economically damaging and how they compare to other invaders (hereafter, other) remain unknown. Here, we quantify invasion costs using the most comprehensive global database compiling them (InvaCost). We compare these costs between worst and other species against sectorial, taxonomic and regional descriptors, and examine temporal cost trends. Only 60 of the 100 worst species had invasion costs considered as highly reliable and actually observed estimates (median: US$ 43 million). On average, these costs were significantly higher than the 463 other invasive species recorded in InvaCost (median: US$ 0.53 million), although some other species had higher costs than most worst species. Damages to the environment from the worst species dominated, whereas other species largely impacted agriculture. Disproportionately highest worst species costs were incurred in North America, whilst costs were more evenly distributed for other species; animal invasions were always costliest. Proportional management expenditures were low for the other species, and surprisingly, over twice as low for the worst species. Temporally, costs increased more for the worst than other taxa; however, management spending has remained very low for both groups. Nonetheless, since 40 species had no robust and/or reported costs, the “true” cost of “some of the world’s worst” 100 invasive species still remains unknown.

The objective of this research was to evaluate changes in fish diversity in streams subjected to different intensities of aquaculture production. The differences in the percentage of occupation by aquaculture ponds were used as a proxy for the propagule pressure of Oreochromis niloticus in natural environments and allowed for the classification of streams into three propagule pressure categories: no propagule, moderate, and intense. A species-rank abundance in the three propagule categories was conducted. Fish presence and absence data, and abundance of fish species were used as proxy to test the effect of aquaculture on fish assemblages. A total of 70 species were sampled, and O. niloticus was captured only in streams where aquaculture was developed. We found that O. niloticus increases its abundance as aquaculture propagule pressure also increases. Oreochromis niloticus was the 17th most abundant species in the moderate category, and the 6th species in the intense category. Fish composition (presence x absence, and abundance data) differed significantly among the propagule pressure categories, with species richness greater in no propagule pressure. These findings reinforce the role of aquaculture as a vector of invasive fish into Neotropical streams, where they can develop self-sustainable populations and impact native fish diversity.

The factors that determine patterns of non-native species richness and abundance are context dependent in both time and space. Global change has significantly boosted plant invasions in mountains, therefore, understanding which factors determine the invasion and at what scale they operate are fundamental for decision-making in the conservation of mountain ecosystems. Although much evidence has been gathered on the patterns of non-native species in mountain ecosystems, little is known about what specific abiotic, biotic, or anthropogenic factors are driven such patterns. Here, we assessed the importance of anthropogenic, biotic, and abiotic factors at two spatial scales as drivers of plant invasions along three roads in south-central Chile. We sampled non-native plant richness and abundance, and each of these explanatory factors, in-situ in 60 transects in disturbed areas and adjacent undisturbed vegetation. Low elevation areas were the most invaded, with patterns of richness and abundance driven mainly by anthropogenic factors, explaining between 20 and 50% of the variance for the three roads. Only for the abundance of non-native species along the road in the Malalcahuello National Reserve, biotic factors were more important (45% of the variance). At the regional scale, the abundance of non-native species was again explained best by anthropogenic factors (24% of the variance), yet non-native richness was driven most strongly by abiotic factors such as soil nitrogen content and pH (15% of the variance). Our results confirm the conclusions from experimental studies that anthropogenic factors override abiotic factors and are important drivers of non-native species at local and regional scales and that non-native plant invasion in mountains is currently not strongly limited by climate.

Management of invasive species often raises substantial conflicts of interest. Since such conflicts can hamper proposed management actions, managers, decision makers and researchers increasingly recognize the need to consider the social dimensions of invasive species management. In this exploratory study, we aimed (1) to explore whether species’ taxonomic position (i.e. animals vs. plants) and type of invaded landscape (i.e. urban vs. non-urban) might influence public perception about the management of invasive species, and (2) to assess the potential of public awareness to increase public support for invasive species management. We reviewed the scientific literature on the conflicts of interest around the management of alien species and administered two-phased questionnaires (before and after providing information on the target species and its management) to members of the public in South Africa and the UK (n = 240). Our review suggests that lack of public support for the management of invasive animals in both urban and non-urban areas derives mainly from moralistic value disagreements, while the management of invasive plants in non-urban areas mostly causes conflicts based on utilitarian value disagreements. Despite these general trends, conflicts are context dependent and can originate from a wide variety of different views. Notably, informing the public about the invasive status and negative impacts of the species targeted for management appeared to increase public support for the management actions. Therefore, our results align with the view that increased public awareness might increase the public support for the management of invasive species, independent of taxonomic position and type of landscape.

Interdisciplinarity is needed to gain knowledge of the ecology of invasive species and invaded ecosystems, and of the human dimensions of biological invasions. We combine a quantitative literature review with a qualitative historical narrative to document the progress of interdisciplinarity in invasion science since 1950. Our review shows that 92.4% of interdisciplinary publications (out of 9192) focus on ecological questions, 4.4% on social ones, and 3.2% on social-ecological ones. The emergence of invasion science out of ecology might explain why interdisciplinarity has remained mostly within the natural sciences. Nevertheless, invasion science is attracting social–ecological collaborations to understand ecological challenges, and to develop novel approaches to address new ideas, concepts, and invasion-related questions between scholars and stakeholders. We discuss ways to reframe invasion science as a field centred on interlinked social–ecological dynamics to bring science, governance and society together in a common effort to deal with invasions.

The Iberian Peninsula is a primary entry point for non-native species (NNS) into Europe via maritime routes, and is a significant tourist destination. This positions the highly diverse Spanish National Parks at high risk from invasive species, necessitating proactive adaptation and mitigation strategies. We present a comprehensive analysis of the risks posed by NNS to the network of 15 continental and marine National Parks in Spain under climate change, aiming to align management strategies with international Global Biodiversity Framework (GBF) targets. We identified 200 NNS across the network of National Parks, including 78 listed in national NNS regulations. Park managers helped identify 22 priority NNS, including the water hyacinth, American mink, Cape fig and wakame, among others. Over half of the 22 priority NNS (55%) were classified as having a “Major” impact on native biodiversity according to EICAT standards, with another 23% considered “Massive”. Distribution models suggest that rising minimum temperatures could enable NNS to expand in altitude within the parks, particularly in high-mountain parks. Species like the barbary sheep, water hyacinth and largemouth bass may particularly benefit from global warming. Our findings prioritize national parks most vulnerable to the double threat posed by climate change and invasive species, such as Islas Atlánticas, Doñana and Archipelago de Cabrera. We conclude that, in order to progress towards achieving GBF goals, it is essential to: (i) coordinate NNS management efforts across administrations (national and regional), (ii) integrate resources and expertise in a unified strategy against invasion across the network and (iii) enhance public awareness about the risks of introduction and impact of NNS.

Alien or non-native species are defined as species living outside their natural distributional ranges. The spread of alien species is increasing globally as a result of rapid technological advances and globalization. Recent investigations have estimated global hotspots of alien established species on the basis of geopolitical boundaries, including Dawson et al. (in: Nat Ecol Evol 1:186. https://doi.org/10.1038/s41559-017-0186, 2017). In particular, these investigations do not consider Intra-Country Established Alien Species, i.e., successful introductions that occur among regions within the same country. In continental countries such as Brazil, the USA and China, studies excluding Intra-Country Established Alien Species (IEAS) waste essential information. Here, we argue that researchers should also consider intra-country introductions when estimating and addressing the risks of alien introductions. By using detailed data for freshwater fish including IEAS in large countries, we demonstrate that novel hotspots for IEAS have arisen worldwide. We illustrate emblematic examples of IEAS, as well as their vectors and negative impacts, to demonstrate the range of impacts that might be missed when excluding IEAS data from analysis. We recognize the need for generalizations, but generalizations based on incomplete data can misinform conservation efforts, particularly in megadiverse regions. Ignores IEAS influences how we count non-native species, invasions and perceive invisibility and impacts. Consequently, upcoming records and analysis of invasion patterns and management of aliens and EAS global hotspots must account for such biases in quantifying the IEAS portion.

The use of long-term datasets is crucial in ecology because it provides a comprehensive understanding of natural fluctuations, changes in ecosystems over extended periods of time, and robust comparisons across geographical scales. This information is critical in detecting and analysing trends and patterns in species populations, community dynamics, and ecosystem functioning, which in turn helps in predicting future changes and impacts of human activities. Additionally, long-term data sets allow for the evaluation of the effectiveness of conservation efforts and management strategies, enabling scientists and decision makers to make evidence-based decisions for biodiversity conservation. Although the use of long-term data is recognized as highly important in several scientific disciplines, its usage remains undervalued regarding questions in invasion science. Here, we used four regional subsets (i.e. England, Hungary, Denmark and the Dutch-German-Luxembourg) of a recently collated long-term time series database to investigate the abundance and dynamics of occurring non-native species over space and time in Europe. While we found differences in the numbers of non-native species across the studied regions (Dutch-German-Luxembourg region = 37; England = 17, Hungary = 34; Denmark = 3), non-native species detection rates were continuous over time. Our results further show that long-term monitoring efforts at large spatial scales can substantially increase the accuracy and rate at which non-native species are detected. This information can inform management endeavours dealing with non-native species, underlining the need for invasion scientists and authorities-stakeholders to make more effort in collecting, analysing and making available long-term datasets at broader geographic ranges.

The introduction of invasive species increases interspecific competition with native species, especially if the invasive fish have a similar ecological role in the ecosystem. The vacant niche hypothesis postulates that an invasive species may be a stronger competitor if it has, additionally to a native species niche, access to a food unavailable to native species. However, there are very few model examples of nearly identical invasive and native species differing in trophic niche utilization. The once common crucian carp (Carassius carassius) has become endangered or extirpated in many regions of Europe mainly due to the invasion of gibel carp (C. gibelio). To estimate the trophic niche divergence between gibel and crucian carp living in syntopy, a non-lethal method of stable isotope analysis (SIA) of fish scales (δ13C and δ15N) was employed. Samples were collected from four sites in the Czech Republic to determine the overlap and sizes of the trophic niches of these two species. The results showed that at two sites, gibel carp had significantly lower δ15N than crucian carp, indicating its lower trophic position. The gibel carp also significantly higher δ13C at two sites indicating higher utilization of littoral sources compared to crucian carp. In addition, isotopic niches partially overlapped at the four study sites, with the most divergent trophic niches found in the macrophyte-rich site. Finally, the gibel carp had higher probability to occur within the crucian carp niche space than vice versa. Our results provide support for the vacant niche hypothesis, indicating that invasive gibel carp gain a competitive advantage over the native crucian carp via feeding on plant material that is underexploited by native crucian carp. Furthermore, data suggest that more “natural” environmental conditions, such as a rich littoral zone, may help to decrease isotopic niche overlap between the two species. Lower trophic position and higher reliance on unexploited food sources seem to contribute to the competitive superiority of the invasive gibel carp over the native crucian carp.