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Four species of the genus Lepidonotus (Annelida, Polynoidae) have been listed in the Mediterranean, including L. carinulatus (Grube, 1869), L. squamatus (Linnaeus, 1758), L. tenuisetosus (Gravier, 1902) and L. clava (Montagu, 1808), although recent studies confirmed only the presence of the two latter. Based on materials collected in the Radès Area (Gulf of Tunis, Western Mediterranean), we provide a characterization of a population of L. tenuisetosus based on key morphological characters and body width/length relationships and conclude that all previously known Mediterranean reports from Israel, Croatia, Greece, Spain and Turkey did not belong to L. tenuisetosus, but either to L. carinulatus , L. clava or to other, non-identified species. Therefore, our finding represents not only the first correct record of L. tenuisetosus for the Tunisian waters and the Western basin, but for the whole Mediterranean Sea, and allows us to discuss on the possible reasons explaining the presence of this and other species of Lepidonotus in the Mediterranean.

While decision-making can benefit from considering positive and negative outcomes of change, over the past half-century, research on non-native species has focused predominately on their negative impacts. Here we provide a framework for considering the positive consequences of non-native species relative to relational, instrumental, and intrinsic values. We demonstrate that their beneficial outcomes are common and profoundly important for human well-being. Identified benefits include social cohesion, cultural identity, mental health, food and fuel production, regulation of clean waters, and attenuation of climate change. We argue that long-standing biases against non-native species within the literature have clouded the scientific process and hampered policy advances and sound public understanding. Future research should consider both costs and benefits of non-native species.

With the population increasing, fish communities, as important components in the river system, were inescapably impacted by human activities. To investigate these impacts, we characterized the fish community's composition by environmental DNA metabarcoding in the urban and suburban sites along Xiang River in central China. The results showed that 32 species were identified, and most species were from Cypriniform. The analysis indicated no significant differences in fish communities among the three urban areas. However, significant differences were observed between the bank solidified and non-solidified areas, which indicated that the channelization significantly influenced the biodiversity and abundances. An alien species, Clarias gariepinus, was discovered in all examined sites, and it was negatively associated with ten native species. Furthermore, human populations and acidification were also negatively related to diversity. Our findings clearly showed that the consequences of anthropogenic activities shaped ichthyofauna and caused biodiversity loss in the urban river.

Positive interactions have been hypothesized to influence plant community dynamics and species invasions. However, their prevalence and importance relative to negative interactions remain unclear, but are fundamentally important for both theoretical and applied ecology. We examined pairwise biotic interactions using over 50 years of successional data to assess the prevalence of positive interactions and their effects on each focal species (either native or exotic). We found that positive interactions were widespread and the relative frequency of positive and negative interactions varied with establishment stage and between native and exotic species. Specifically, positive interactions were more frequent during early establishment and less frequent at later stages. Positive interactions involving native species were more frequent and stronger than those between exotic species, reducing the impact of invasional meltdown on succession. Our study highlights the role of positive native interactions in shielding communities from biological invasion and enhancing the potential for long-term resilience.

AimMutualistic interactions between plants and animals are fundamental for the maintenance of natural communities and the ecosystem services they provide. However, particularly in human-dominated island ecosystems, introduced species may alter mutualistic interactions. Based on an extensive dataset of plant–frugivore interactions, we mapped and analysed a meta-network across the Caribbean archipelago. Specifically, we searched for subcommunity structure (modularity) and identified the types of species facilitating the integration of introduced species in the Caribbean meta-network.LocationCaribbean archipelago (Lucayan archipelago, Greater Antilles, Lesser Antilles).MethodsWe reviewed published scientific literature, unpublished theses and other nonpeer-reviewed sources to compile an extensive dataset of plant–frugivore interactions. We visualized spatial patterns and conducted a modularity analysis of the cross-island meta-network. We also examined which species were most likely to interact with introduced species: (1) endemic, nonendemic native or introduced species, and (2) generalized or specialized species.ResultsWe reported 3060 records of interactions between 486 plant and 178 frugivore species. The Caribbean meta-network was organized in 13 modules, driven by a combination of functional or taxonomic (modules dominated by certain groups of frugivores) and biogeographical (island-specific modules) mechanisms. Few introduced species or interaction pairs were shared across islands, suggesting little homogenization of the plant–frugivore meta-network at the regional scale. However, we found evidence of “invader complexes,” as introduced frugivores were more likely to interact with introduced plants than expected at random. Moreover, we found generalist species more likely to interact with introduced species than were specialized species.Main conclusionsThese results demonstrate that generalist species and “invader complexes” may facilitate the incorporation of introduced species into plant–frugivore communities. Despite the influx of introduced species, the meta-network was structured into modules related to biogeographical and functional or taxonomic affinities. These findings reveal how introduced species become an integral part of mutualistic systems on tropical islands.1 INTRODUCTIONMutualistic interactions between plants and animals, such as pollinators and frugivores, are critically important for maintaining the functionality of natural communities (Jordano, 1987;Ollerton et al., 2011; Rech et al., 2016). While most flowering plants are dependent on animals for pollination and seed-set (Ollerton et al., 2011; Rech et al., 2016), animal frugivores may ingest or otherwise manipulate and consequently disperse millions of seeds annually (Bueno et al., 2013). Frugivory is thereby crucial for the maintenance of plant diversity (Harms et al., 2000), as it allows plants to populate new sites, maintains gene flow between distinct populations and decreases density-dependent mortality in proximity of the parent individuals (Rogers et al., 2021). In some tropical systems, approximately 90% of all woody plants depend on frugivores for seed dispersal (Almeida-Neto et al., 2008; Howe & Smallwood, 1982). In addition to providing direct dispersal to specific, favourable sites for the plant (Wenny & Levey, 1998), frugivores can enhance the probability of successful germination, for example through the passage of seeds in the intestinal system (e.g. Traveset et al., 2001). The most important frugivore groups are birds, mammals and reptiles with birds and reptiles being particularly important in tropical island ecosystems (Kaiser-Bunbury et al., 2010; Valido & Olesen, 2007).Globally, co-evolved plant–frugivore communities are suffering from an array of drivers associated with global change, such as the introduction of species into new environments, where they become integrated into local communities through species interactions (Gallardo et al., 2016; Vilà et al., 2011). Species communities are thus being altered, which in turn may have consequences for biotic interactions and ecosystem functions, such as seed dispersal (Aslan et al., 2013; Lugo et al., 2012; Traveset & Richardson, 2006; Vizentin-Bugoni et al., 2021). Island ecosystems are particularly vulnerable to the disruption of native plant–frugivore interactions as island mutualists have evolved in isolation, and frequently developed specific traits, such as altered dispersal, or loss of defence traits in plants (Burns, 2019). Furthermore, as islands harbour many endemic species found nowhere else on Earth (Kier et al., 2009; Paulay, 1994), and have experienced disproportionally high extinction rates and numerous extant island species are threatened with extinctions (Blackburn et al., 2004; Fernández-Palacios et al., 2021; Groombridge, 1992), it is especially important to understand how introduced species integrate into island communities (Wood et al., 2017).Introduced species may integrate into existing communities and establish themselves in different ways. For instance, the concept of “invader complexes” suggests that introduced species facilitate the establishment of other introduced species, resulting in groups of introduced species interacting strongly with each other and less with the remaining community (D'Antonio & Dudley, 1993). Alternatively, endemic species that have become superabundant and highly generalized species due to ecological release and density compensation may readily include new arrivals into their interactions and thereby facilitate the establishment of introduced species on islands (Olesen et al., 2002). Furthermore, a growing number of studies show that species with many mutualistic partners (i.e. generalized species irrespectively of being nonendemic native or endemic) are more likely to incorporate new partners into their networks (Bascompte & Stouffer, 2009; Maruyama et al., 2016). In network theory, this is called “preferential attachment” (Newman, 2001), and thus, most generalized species would be expected to interact with introduced species.In addition to understanding which species are responsible for incorporating introduced species into native communities, we have little quantitative understanding of how introduced species affect the structure of native interaction networks and how this varies biogeographically (Fricke & Svenning, 2020). As for other mutualistic networks, plants and frugivores form complex interaction networks with reccurring structural properties (Bascompte & Jordano, 2007). One such property of interaction networks is modularity, which describes how interacting species aggregate into modules consisting of species that interact strongly within the respective module but much less with species of other modules (Thébault, 2013). The modular structure of mutualistic networks may reflect “co-evolutionary units” (Olesen et al., 2007) determined by an array of factors, such as phenological overlap, morphological traits, taxonomic relatedness and biogeography (Araujo et al., 2018; Dalsgaard et al., 2013; Donatti et al., 2011; Martín González et al., 2018; Maruyama et al., 2014; Schleuning et al., 2014). However, it is poorly understood whether introduced species influence the modular structure of mutualistic systems.Here, we present an extensive dataset on plant–frugivore interactions compiled from published and unpublished resources across the islands of the Caribbean archipelago: Lucayan archipelago, Greater Antilles and Lesser Antilles. We use the data to (i) explore the distribution of frugivory records across the Caribbean islands; (ii) assess island connectivity through shared species and interactions; (iii) evaluate the modular structure of the regional plant–frugivore meta-network and (iv) determine whether generalized vs. specialized species and introduced vs. endemic species are more likely to integrate introduced plants and frugivores into native plant–frugivore communities in island systems.2 METHODS2.1 Data collection and study regionAll our data were collected on the Caribbean islands, that is the Lucayan archipelago (The Bahamas and Turks and Caicos), the Greater Antilles (Cuba, Cayman Islands, Jamaica, Hispaniola and Puerto Rico) and the Lesser Antilles (a series of islands from the US and British Virgin Islands in the north to Grenada in the south). We did not include plant–frugivore interactions from islands such as Trinidad and Tobago, Curaçao, and Bonaire just north of South America, as these are continental islands with biotas with strong affinities to the South American mainland (Carstensen et al., 2012; Ricklefs & Bermingham, 2008). The low-lying sedimentary islands of the Lucayan Archipelago are part of the North American platform (Iturralde-Vinent & MacPhee, 1999; Trejo-Torres & Ackerman, 2001), and some of the islands have been interconnected in the Pleistocene (Murphy et al., 2004; Trejo-Torres & Ackerman, 2001). The mostly large and mountainous islands of the Greater Antilles are old with different geological origins (Graham, 2003; Iturralde-Vinent & MacPhee, 1999). The Greater Antilles emerged as fragments in the Eocene about 49 Ma; the geological history of the region has been highly dynamic with some parts connected in the past (Buskirk, 1985; Graham, 2003; Iturralde-Vinent & MacPhee, 1999; Ricklefs & Bermingham, 2008). The current biota of the Greater Antilles was only in small parts formed by vicariance, with dispersal facilitated by the Aves Ridge about 32–35 Ma (Iturralde-Vinent & MacPhee, 1999) or a more likely overwater dispersal at least for the avifauna (Buskirk, 1985; Graham, 2003; Ricklefs & Bermingham, 2008). The Lesser Antilles form a volcanic arc where the North and South American plates subduct under the Caribbean plate and likely originated at least 20 Ma (Ricklefs & Bermingham, 2008). To the east of the volcanic arc are some younger and low-lying islands such as Antigua and Barbuda, which consist of uplifted marine sediments (Ricklefs & Bermingham, 2008; Ricklefs & Lovette, 1999). Some islands were interconnected during the last glacial maximum, but most Lesser Antilles islands have never been interconnected (Ricklefs & Bermingham, 2004, 2008). The isolation of the Caribbean islands from the mainland differs greatly (Carstensen et al., 2012). Bimini in the Bahamas, for instance, is only approx. 87 km from the North American continent and Grenada in the Lesser Antilles is only 137 km from the continental landmass of South America. By contrast, islands such as Grand Turk (993 km) and South Caicos (999 km) are much more isolated from the mainland. On average, the isolation from any continental landmass in the Caribbean is over 500 km (Mean: 593 km ± 248 km SD; see details in Supporting Information Table S1). The distances between single islands are much smaller, for example the distance between Martinique and Dominica and Martinique and Saint Lucia is approx. 40 km. An island size threshold of 10,000 km2 has previously been suggested to be important for islands to be considered sources for colonization (Weigelt & Kreft, 2013), and on average, the islands of the Caribbean are approx. 304 km (±174 km SD) from the nearest island that exceeds 10,000 km2 (Table S1). Given the geological history and isolation of the Caribbean, the biota is characterized by being depauperate with high levels of endemism.To collect data on interactions between plants and frugivores in the Caribbean, we screened the Web of Science (WoS) and Google Scholar search engines. We used the combination of the following search terms: (“frugivory” OR “seed dispersal” OR “seed removal” OR “mutualism”) AND (“Caribbean” OR “Lesser Antilles” OR “Greater Antilles” OR “West Indies” OR “Bahamas” OR “Turks and Caicos” OR “Cayman Islands” OR “Jamaica” OR “Cuba” OR “Hispaniola” OR “Haiti” OR “Dominican Republic” OR “República Dominicana” OR “Puerto Rico” OR “Mona” OR “Virgin Islands” OR “Saint Martin” OR “Anguilla” OR “St. Kitts and Nevis” OR “Antigua” OR “Barbuda” OR “Montserrat” OR “Guadeloupe” OR “Dominica” OR “Martinique” OR “St. Lucia” OR “St. Vincent” OR “Grenadines” OR “Barbados” OR “Grenada”). To also include the grey literature, we contacted local ornithologists and ecologists working in the Caribbean region. This approach allowed us to obtain non-English publications, such as theses and dissertations not available online. We screened each of the studies manually, discarding studies where no appropriate data were presented (e.g. mutualistic interactions in marine environments). Interactions were only included when the respective authors presented original evidence for interaction events, that is evidence of fruits and/or seeds being ingested by frugivores. Thus, we discarded records where interactions between species were speculative (e.g. observation of frugivores on fruiting plant species without any evidence of fruit ingestion).We standardized the species names of plants and frugivores using the R-package taxize (Chamberlain & Szocs, 2013; Global Names Resolver, 2021) and data from the Integrated Taxonomic Information System (ITIS, 2021). We also retrieved information about species taxonomies (i.e. class, order and family) from ITIS. Finally, we compiled information about the native status of species and classified them into nonendemic native (species native to the Caribbean, but also naturally occurring elsewhere), endemic (only occurring within the Caribbean) and introduced (not naturally occurring within Caribbean) species (see details in Supporting Information Text S1). Of the original records, 95 plant (approx. 16% of all reported plants) and one frugivore record were not identified to species level (e.g. only genus name reported) and were thus excluded from data analyses. The final data used in statistical analyses consisted of interactions between 486 plant and 178 frugivore species.2.2 Data analysis2.2.1 Cross-island patterns of shared species and interactionsWe summarized patterns of shared species and interaction pairs across the Caribbean by calculating the proportion of shared species and interaction pairs across all islands. We calculated this proportion as the number of species/interaction pairs found on any two islands, divided by the total number of species/interaction pairs found on the given islands (Fricke & Svenning, 2020). We summarized these patterns separately for all reported records, for endemic, nonendemic native and for introduced plant and frugivore species and interaction pairs, respectively.2.2.2 Modularity of the Caribbean plant–frugivore meta-networkTo detect a modular structure of the meta-network, that is the network of plant–frugivore interactions across all islands, we employed Beckett's DIRT-LPA algorithm in the computeModules function of the R-package “bipartite” (Dormann et al., 2008, 2009). We ran 10 independent runs of the algorithm on the binary meta-network containing interactions between all identified species and identified the run with the single best division into modules, that is the highest degree of modularity Q. For the run with the highest Q value, we recorded the Q value, the number of modules as well as the respective plant and frugivore species in each module (Schleuning et al., 2014) and the islands on which they were recorded. To test whether the identified modular structure of the meta-network differed from random, we compared our results to 100 null models. To this end, we used an algorithm proposed by Patefield (1981) to randomize the interactions between species, using fixed marginal totals to produce networks with randomly associated species without constraining the degree of specialization (Blüthgen et al., 2008; Schleuning et al., 2014). For each of the null models, we applied the same approach as with the original matrix, that is we identified the single best configuration from 10 independent runs (Schleuning et al., 2014). We then tested whether modularity of the original matrix was significantly different from the best 100 null models by looking at the proportion of null modularity values that were greater than the empirical one, that is if .05; Figure S2c) and the frugivore perspective (slope = 0.003, p > .05; Figure S2d).4 DISCUSSIONHere, we present a comprehensive review of published plant–frugivore interactions across the Caribbean archipelago, including the Lucayan archipelago, the Greater and Lesser Antilles. All islands shared species and unique interaction pairs with neighbouring islands and archipelagos, thereby forming a cohesive meta-network. We show that the meta-network of plant–frugivore interactions across the Caribbean was structured into modules, with at least some modules determined by a combination of functional or taxonomic (i.e. certain groups of frugivores) and biogeographical (i.e. island-specific modules) mechanisms. While relatively few species in the dataset were introduced to the Caribbean (16% plant and 8% frugivore species), we found support for the “invader complexes” theory, whereby introduced species facilitate the establishment of other introduced species (D'Antonio & Dudley, 1993; Olesen et al., 2002). Moreover, we found that generalized species were more likely to incorporate introduced species into their interactions, giving support for the “preferential attachment” theory (Newman, 2001). Below, we first discuss the available data on frugivory in the Caribbean, whereafter we discuss how species and interactions are shared across islands. We end by discussing the drivers of modularity and the integration of introduced species into plant–frugivore communities across the Caribbean.4.1 Data on frugivores and their plants in the Caribbean archipelagoAcross all islands, the vast majority of reported frugivores were birds (79%), followed by reptiles (13%) and mammals (8%), of which in turn the majority were bats (71%). These data thus reflect patterns that are typical for oceanic islands, as there is generally a lack of nonvolant, large-bodied, frugivorous mammals which may be ecologically replaced by birds and reptiles (Kaiser-Bunbury et al., 2010). The low number of mammal species in the dataset could also reflect past mammal extinctions particularly on the islands of the Greater Antilles (Turvey et al., 2021), potentially leaving some plants without their main seed dispersers.A large proportion of the plant species (28%) and the majority of frugivore species in the dataset (65%) were classified as endemic to the Caribbean. High degrees of endemism in local species communities are characteristic of island ecosystems (Kier et al., 2009; Paulay, 1994). In a review of plant–frugivore interactions on the Galapagos archipelago, Heleno et al. (2011) found similarly high proportions of endemic frugivores in the species pool (71%), underlining the importance of endemic frugivores for island communities. By contrast, only a few species in the dataset were classified as introduced to the Caribbean (16% plants and 8% frugivores), which was lower than other studies on island ecosystems. Notably on Hawai'i, the proportion of introduced seed disperser species ranged from 50% to 100% for plants and from 60% to 100% for birds (Vizentin-Bugoni et al., 2019). On the Galapagos, the proportion of introduced plants and frugivores was 28% and 23%, respectively (Heleno et al., 2011). However, on the Galapagos, all introduced frugivore species were mammals, whereas in our data, the vast majority of introduced species were birds (86%) and only two species (14%) were mammals (a primate: Chlorocebus pygerythrus and a carnivore: Herpestes javonicus).4.2 Cross-island patterns of shared species and interactionsWhen examining the role of different groups of plants and frugivores in connecting islands and archipelagos, we found that nonendemic native species and interaction pairs were shared most widely across islands (Figure 2), which is expected, as these species are widespread species occurring throughout the Caribbean and the Neotropical mainland. They are thus supposedly good dispersers, and their ranges often occur across multiple islands and cross-borders of archipelagos (Dalsgaard et al., 2014). Although endemic frugivores made up more than 60% of the frugivore species, generally they overlapped much less between islands compared to nonendemic natives, which only accounted for less than 30% of the frugivores in the data (Table 2). This pattern is not surprising, since the distributional ranges of endemic species are per definition confined within limited geographical areas (Kricher, 2011), many species being single-island endemics or occurring on few islands within each of the archipelagoes, that is the Lucayan archipelago, the Greater and Lesser Antilles (Dalsgaard et al., 2014). In the Caribbean, for instance, there is a high number of single-island endemic frugivorous birds, such as various species of parrots like the Saint Vincent Parrot Amazona guildingii (Birds Caribbean, 2021). Introduced plant species were shared widely across the Caribbean (Figure 2), which was expected, as most were agricultural and widely cultivated plants, reflecting that the Caribbean is historically heavily impacted by humans (Kemp et al., 2020; Walters & Hansen, 2013). By contrast, introduced frugivores were reported on few islands only (Table 2), and these islands shared mostly low proportions of introduced frugivores (Table S4); introduced interaction pairs were almost not shared between islands. Globally, a recent study showed how introduced species caused an increase in the proportion of regions sharing species and interactions (Fricke & Svenning, 2020), demonstrating that species introductions led to increasing similarity and homogenization in plant–frugivore communities across the world (Fricke & Svenning, 2020). In the Caribbean, however, given our data, especially nonendemic natives played a bigger role in interconnecting islands.4.3 Modularity of the Caribbean plant–frugivore meta-networkThe Caribbean plant–frugivore meta-network was organized in modules, as are most mutualistic plant–animal interaction networks, both local networks (e.g. Dalsgaard et al., 2013; Dupont & Olesen, 2009; Mello et al., 2011a, 2011b; Olesen et al., 2007) and meta-networks (Araujo et al., 2018; Emer et al., 2018; Martín González et al., 2018). The separation of the meta-network into modules was at least partly driven by functional or taxonomic (i.e. modules dominated by certain species groups) and biogeographical (i.e. island-specific modules) mechanisms. For instance, one module consisted of small- to medium-sized bird species recorded in Jamaica (100% birds; 88% of frugivores recorded in Jamaica; module nine in Figure 4). Another module consisted mostly of various bat species (63% bats) recorded in Cuba (88% of frugivores recorded in Cuba; module one in Figure 4), whereas another module consisted almost exclusively of rock iguanas (Cychlura spp.) found in the Bahamas only (88% Iguanas; 88% of frugivores were recorded on the Bahamas only; module 13 in Figure 4). These modules associated with specific functional/taxonomic groups or specific islands were thus positioned in the periphery of the Caribbean meta-network (Figure 3). The separation into modules according to biogeographical affinities, such as single islands, was expected given that interactions between plants and frugivores are inherently spatial as species must be in the same place to interact (Morales & Vázquez, 2008) and many species are restricted to specific islands. Spatial patterns that correspond to insularity in the broad sense have previously been shown to partially explain the modular structure of mutualistic plant–animal networks in landscape matrices, where species are restricted to different types of patchily distributed habitats (Maruyama et al., 2014). Patterns of modularity have also previously been suggested to be explained by behavioural or functional traits of species (Dicks et al., 2002; Donatti et al., 2011; Maruyama et al., 2014). In plant–frugivore interactions, although plants typically aim to attract functionally diverse seed dispersers (Plein et al., 2013), there is evidence of functional matching between interaction partners, especially with birds (Vollstädt et al., 2017). Morphologically different frugivore species tend to forage on morphologically distinct sets of plant species (Dehling et al., 2016; Gautier-Hion et al., 1985; Lomáscolo et al., 2010; Mello et al., 2011b), which might be reflected in the modules composed primarily of specific frugivore groups with characteristic morphological and functional traits. Bats, for instance, consume different types of fruits than birds and may show a clear separation in their dietary composition (Gorchov et al., 1995). The patterns of modularity we detected were therefore in line with expectations of functional/taxonomic and biogeographical mechanisms as drivers of modularity. However, there were also modules consisting of a mix of species from various islands. One module consisted of about 50% of large parrot species (Amazona spp.), but the frugivores were recorded in the entire Caribbean (module six in Figure 4) and, notably, the module in the centre of the Caribbean meta-network consisted of various types of frugivores occurring throughout the Caribbean, thereby interconnecting islands and archipelagos in the Caribbean meta-network (module seven; Figure 3 and Table S5).4.4 Interactions with introduced speciesRegarding how introduced species were integrated into the meta-network, we found that nonendemic native and endemic plants and frugivores interacted significantly less with introduced frugivore species than expected at random (Figure 4a,b). Among Caribbean frugivores and their fruiting plants, there is therefore no support for the idea that endemic super-generalists are the main facilitators of introduced species, as suggested for pollination networks on tropical islands (Olesen et al., 2002). On the contrary, introduced frugivores were recorded interacting with introduced plants significantly more often than expected at random (Figure 4c). This pattern suggests that introduced frugivores “prefer” to feed on introduced plants, which in turn suggests the presence of “invader complexes,” that is introduced species interacting more among themselves than expected at random, thus facilitating their establishment (D'Antonio & Dudley, 1993). Such facilitation processes between introduced species can lead to “invasional meltdowns,” as large groups of introduced species may have increasingly negative impacts on native communities (Jeschke et al., 2012; Simberloff & von Holle, 1999). Other island ecosystems have been found to be even more dominated by introduced frugivores, notably Hawai'i is almost exclusively dominated by introduced frugivores, as most of the endemic species have gone extinct (Vizentin-Bugoni et al., 2019; Vizentin-Bugoni et al., 2021). These findings from various archipelagos are concerning, regarding the potential impact of introduced species on native ecosystems. Such findings are particularly worrying when considering that on other island ecosystems, introduced species were also more often involved in seed-dispersal interactions (rather than seed/pulp predation) than native species (Heleno et al., 2011; Vizentin-Bugoni et al., 2019, 2021). For many of the interaction records, our data do not distinguish between seed-dispersal interactions or seed/pulp predation events; thus, it is not possible to estimate the effect of introduced species on local native and endemic plant communities in the Caribbean. Nevertheless, in Hawai'i, it was shown that introduced frugivores do not sufficiently replace the species roles of lost seed dispersers, since they preferentially disperse seeds of introduced rather than native plants (Vizentin-Bugoni et al., 2019). This raises the question why introduced plant species seem so attractive. One reason could be that introduced plants may have specific traits, such as longer fruiting duration, which increase the probability of encounters and are therefore more likely to be consumed by frugivores (Heleno et al., 2011; Sperry et al., 2021). In the Caribbean meta-network, many of the observations were from agricultural areas, where agricultural plants such as Mangifera indica (Mango) are often abundant with large crops, and although they are not dispersed by any native frugivore, they do overall attract many frugivores. Fruiting plant and thus resource abundance is in turn linked to increased fruit consumption, because frugivores often track available fruits in the landscape (Quitián et al., 2019), and consequently, the patterns we find may be partially driven by the high abundance of introduced agricultural plants and their crop sizes in human-dominated environments. Such patterns may be more pronounced on densely populated islands than on islands with few people and relatively more protected areas.In addition to “invader complexes,” we found that generalist species, that is species with many interaction partners, were more likely to interact with introduced species, which was consistent for both plants and frugivores (Figure S2a,b). These results are in line with previous findings, underlining the importance of highly generalized species for the establishment of introduced species, especially on islands (Maruyama et al., 2016). This gives support for the “preferential attachment” hypothesis (Newman, 2001), that is that species with wide ecological niches include and facilitate the establishment of new species, such as introduced species on islands. Our finding that generalized species do not have a higher proportion of interactions with introduced partners in their total set of interactions than specialized species (Figure S2c,d) reflects the overall low numbers of introduced species in the Caribbean data. Since only few of the potentially available interaction partners are introduced species, generalized species with many interaction partners would also be expected to have a decreasing proportion of their interactions with introduced species. Thus, although generalized species are likely to incorporate introduced species into their niche (Figure S2a,b), they do not have a specific preference for introduced species (Figure S2c,d).5 CONCLUSIONSBased on a comprehensive review of accessible data on plant–frugivore interactions, we showed that the Caribbean meta-network is structured into modules and demonstrate how introduced species are integrated into native communities in the Caribbean archipelago. These results provide valuable insight into plant–frugivore interactions in insular biodiversity hotspots, showing how insular plant–frugivore systems are susceptible to invasion. Future studies are needed to demonstrate the importance of introduced species as seed dispersers compared with seed/pulp predators (Nogales et al., 2017). Specifically, research quantifying the relative importance of different frugivore groups as seed dispersers and their respective effectiveness is lacking for most plant–frugivore interactions in the Caribbean. This would provide valuable information and could help with the conservation of endemic plants in the Caribbean archipelago. Moreover, we also in general lack information on frugivory in the Caribbean. Kim et al. (2022) reported 4336 species of plants with animal-dispersal syndromes in the Caribbean archipelago, and our dataset represents only 11% of those species with some regional variation (Table S6). For instance, whereas Puerto Rican plants were covered relatively well (31% of the species), plants in Hispaniola (approx. 7%), Jamaica (approx. 8%) and the Lesser Antilles (approx. 9%) were less well represented. There may also be taxonomical differences in sampling completeness. Palms (Arecaceae) are highly diverse in the Caribbean representing 135 species (Roncal et al., 2008), and our dataset had only 23 palm species (17%). Several endemic and highly threatened fleshy-fruited plants do not have any information on the main seed dispersers (e.g. Catesbea spinosa, Brunfelsia portoricensis, Diospyros spp. and many cactus species). We also have limited and incomplete information on the fruit diet of several endemic frugivores (e.g. pigeons, thrashers and thrushes) that could play an important role for seed dispersal of Caribbean plants. There is therefore an urgent need to increment more scientific information on plant–frugivore interactions in the Caribbean, one of the world's insular biodiversity hotspots.ACKNOWLEDGEMENTSThis work is dedicated to our colleague and coauthor Michel Faife-Cabrera who passed away due to Covid-19 complications. M. Galetti thanks CNPq and University of Miami for financial support. M.G.R. Vollstädt, C. N. Kaiser-Bunbury, B. I. Simmons, F. Gonçalves, and B. Dalsgaard thank the Independent Research Fund Denmark (grant no. 0135-00333B). Funding for A. Strong's work was provided by an NSF grant to T. W. Sherry (Tulane University) and R. T. Holmes (Dartmouth College), the Chicago Zoological Society, Sigma Xi Grants-in-Aid-of Research, the World Nature Association, and The Louisiana Educational Quality Support Fund. A. Strong's work benefitted from collaborations with M. Johnson, T. Sherry, A. Sutton and the late R. Sutton. Funding for S. Schubert's work was provided by Rufford Foundation Small Grants 1, 2, & Booster, in addition to the Old Dominion University Paul W. Kirk Jr Student Research Award, a British Ornithologists' Union Student Research Award, and the BirdsCaribbean David S. Lee Fund. J. Salazar's work was funded by FONDOCyT. (Ministerio de Educaciòn Superior, Ciencia y Tecnología), Project 1B4-9. F. L. Tarazona-Tubens is supported by McKight Fellowship. B. I. Simmons was supported by a Royal Commission for the Exhibition of 1851 Research Fellowship. We also thank all researchers who have worked intensively in the Caribbean.CONFLICT OF INTERESTThe authors declare that there is no conflict of interest to report.Open ResearchSupporting InformationREFERENCESBIOSKETCHMaximilian Vollstädt is an ecologist, and a researcher at the University of Copenhagen, Denmark. His research interests include mutualistic interactions in plant-pollinator and plant-seed disperser communities in tropical island ecosystems.Author contributions: M.G.R.V., M.G., B.D. Conceptualization, Methodology; M.G.R.V., B.I.S. Formal analysis, Visualization; M.G.R.V., M.G., C.N.K.B., B.D. Original draft preparation, Writing; All Authors: Writing, Review & Editing.Volume28, Issue11November 2022Pages 2361-2374FiguresReferencesRelatedInformationRecommendedNatural mixing of species: novel plant–animal communities on Caribbean IslandsA. E. Lugo, T. A. Carlo, J. M. WunderleAnimal ConservationFrugivore distributions are associated with plant dispersal syndrome diversity in the Caribbean archipelagosSeokmin Kim, Lilian Sales, Daiane Carreira, Mauro GalettiDiversity and DistributionsInteractions between resource availability and enemy release in plant invasionDana M. BlumenthalEcology LettersHuman disturbances affect the topology of food websFrederico Mestre, Alejandro Rozenfeld, Miguel B. AraújoEcology LettersA general framework for species-abundance distributions: Linking traits and dispersal to explain commonness and rarityThomas Koffel, Kaito Umemura, Elena Litchman, Christopher A. Klausmeier

Many studies have assessed the various responses of alien plants to changes in overall nutrient or different nitrogen (N) availabilities. However, in natural soils, nutrients are present as different elements (e.g., N and phosphorus [P]) and forms (e.g., inorganic and organic). Few studies have explored whether invasive and native species differ in their responses to varying P availability and forms.We grew five taxonomically related pairs of common herbaceous, invasive and native species alone or in competition under six different conditions of P availability or forms and assessed their growth performance.Invasive species overall did not produce more biomass than native species did in the various P conditions. However, the biomass response to organic forms of P was, relative to the response to inorganic forms of P, stronger for the invasive species than that for the native species and agreed with invasive species mainly allocating biomass to the root system under organic P conditions.While invasive species were not more promiscuous than the native species, they took great advantage of the organic P forms. Therefore, the invasion risk of alien species may increase in habitats with more organic P sources.

Hybridization outcomes vary geographically and can depend on the environment. Hybridization can also reshape biotic interactions, leading to ecological shifts. If hybrids function differently ecologically in ways that enhance or reduce fitness, and those ecological roles vary geographically, ecological factors might explain variation in hybridization outcomes. However, relatively few studies have focused on ecological traits of hybrids. We compared the feeding ecology of Catostomus fish species and hybrids by using stable isotopes (δ

Arbuscular mycorrhizal fungi (AMF) provide crucial support for the establishment of plants in novel environments. We hypothesized that the OTU/genus richness and diversity of soil- and root-associated AMF associated with alien plant species in their exotic ranges are lower than those in their native ranges. We examined the root-associated and soil-dwelling AMF of 11 invasive plant species in their native and exotic ranges in the United States and Europe by DNA sequencing of the ITS2 locus. Examined root-associated AMF assemblages were simplified, which manifested as the loss of several AMF genera in the exotic ranges of the plants. These fungal assemblages were also characterized by greater dominance and simplification of the fungal assemblages. The dominant fungal genera were present regardless of whether their host plants were in their native or exotic ranges. Interestingly, both the native and invaded soils hosted diverse local AMF assemblages. Therefore, alien plant invasions were not limited to soils with low AMF diversity. Some AMF taxa could be context-dependent passengers rather than drivers of alien plant invasions. Further studies should identify functions of AMF missing or less abundant in roots of plants growing in exotic ranges.

In Patagonia (Argentina) two non-native vespid wasps became established in the last decades. Vespula germanica was first detected in 1980 while V. vulgaris arrived some 30 years later. Both species can have a strong negative impact on agriculture, natural environment and on outdoor human activities. Invasion success -the establishment and spread of a species- may be influenced negatively by the degree of interaction with the resident native community, and alien species already present. The sequential arrival of these two wasps allows us to understand key questions of invasion ecology. Additionally, recognizing the outcome of the invasion by vespids in Patagonia -a region lacking native social wasps-, may help plan species-focused mitigation and control strategies. We explored long term species coexistence through the deterministic Lotka-Volterra competition model, using site-specific field data on prey captured (to estimate niche overlap) and current nest densities in sites. Food items carried by workers were similar but there is some degree of segregation. V. germanica nest density in shared sites, and in sites without coexistence, were 3.14 and 3.5 respectively, being higher for V. vulgaris with 4.71 and 5.33. The model predicts stable co-existence of both species in the invaded range, yet a higher abundance of V. vulgaris should be expected. Added to evidence on other foraging behavioral attributes of both wasp species and the invasion patterns observed in other regions, it is likely that the prior presence of V. germanica does not contribute significantly to the biotic resistance of the invaded range for V. vulgaris

International audience; Urbanization of coastal habitats, often exemplified by harbors and marinas, has led to various ecological paradigms, questioning the functioning of these new ecosystems. In the present study we investigated, in a large Mediterranean harbor, whether spatial variation of pollution is present and if this variability drives the structure of the sessile community. We hypothesized locations to have significantly different communities, based on the assumption on the occurrence of environmental gradients of pollution that would constitute selective filters. Three distinct community types were identified in June, coinciding with spatially variable contaminants in sediments. We observed then an unexpected shift of the community between June and August associated to a sharp decrease in biodiversity and a decline of most species, masking the effects of local variation and thus leading to the homogenization of the biodiversity within the harbor. This shift coincided with successive heatwaves (the longest lasting 13 days over 25°C, with a thermal peak at 28°C) which might potentially be associated with a die-off in the harbor communities, regardless of location.

Biological invasions are one of the major threats to the ecosystem structure and functioning. After the initial introduction, frequently mediated by human activities, alien species can overcome different biogeographical and ecological barriers and determine severe impacts on native biodiversity and socio-economic activities. The Italian peninsula is located at the intersection of large trade routes within the Mediterranean Sea. Such position, along with the intense commercial activity and the high population density of the Italian coast, are considered important drivers of alien species in Italian marine and transitional ecosystems. The Italian peninsula, however, is also one of the regions with the highest native species richness within the Mediterranean Sea and, therefore, it is crucial to account for both alien and native species diversity when estimating the impact of biological invasion. Yet, such comprehensive information is frequently scattered across several biodiversity information systems and databases. Here, two datasets with alien and native species records in Italian marine and transitional waters are described. These datasets, created for the LifeWatch Italy case study on alien species, are the result of a large-scale collaboration involving experts working across the whole range of taxonomic diversity. The marine dataset includes a total of 12,219 records belonging to 3,772 species gathered from 91 investigated sites and seven EUNIS habitats. The dataset on transitional waters biodiversity includes 3,838 records belonging to 2,019 species found in 23 locations and four EUNIS habitats. Alien species were recorded in both marine and transitional waters, accounting respectively for 140 and 171 biological records belonging to 59 and 97 species. These occurrence data can be used for further research studies or management purposes, including the evaluation of the invasion risk and the formulation of alien species control and management plans. Furthermore, these compiled datasets can be used as input data for the Biotope vulnerability case study of LifeWatch ERIC, which offers a number of ICT services for the calculation of the incidence and of the impact of alien species on European biotopes.

A colonial ascidian of the genus Distaplia caused a mass mortality of the pen shell Atrina maura (Sowerby, 1835) during June 2016 in the southwest of the Gulf of California (Mexico), with a significant socio-economic cost. Tentatively identified in previous works as Distaplia cf. stylifera, a precise taxonomic determination was still lacking. In the present work, based on a detailed morphological study, it is confirmed that this aggressive species is Distaplia stylifera (Kowalevsky, 1874). Originally described from the Red Sea, the species currently has a wide circumtropical distribution (with the exception of the Eastern Pacific to date) and is reported as introduced in parts of its range. The present account thus represents an important range extension of this species. However, when revising the original description and later observations, the reported variability of several characters makes it likely that the binomen is in fact a complex of species, as is common in other ascidians with wide distributions. A complete morphological and genetic study including populations from the entire range of distribution would be necessary to settle the status of D. stylifera. Taxonomic uncertainties hinder a correct interpretation of biogeographical patterns and inference on the origin of the studied population. Nevertheless, the known introduction potential of the species, coupled with an explosive growth in an anthropized environment, and the lack of any previous reports in the Eastern Pacific, strongly suggest that the investigated population represents yet another instance of ascidian introduction. From the point of view of management, its invasive behavior is cause for great concern and warrants mitigation measures.

The prey naivety hypothesis posits that prey are vulnerable to introduced predators because many generations in slow gradual coevolution are needed for appropriate avoidance responses to develop. It predicts that prey will be more responsive to native than introduced predators and less responsive to introduced predators that differ substantially from native predators and from those newly established. To test these predictions, we conducted a global meta-analysis of studies that measured the wariness responses of small mammals to the scent of sympatric mammalian mesopredators. We identified 26 studies that met our selection criteria. These studies comprised 134 experiments reporting on the responses of 36 small mammal species to the scent of six introduced mesopredators and 12 native mesopredators. For each introduced mesopredator, we measured their phylogenetic and functional distance to local native mesopredators and the number of years sympatric with their prey. We used predator and prey body mass as a measure of predation risk. Globally, small mammals were similarly wary of the scent of native and introduced mesopredators; phylogenetic and functional distance between introduced mesopredators and closest native mesopredators had no effect on wariness; and wariness was unrelated to the number of prey generations, or years, since first contact with introduced mesopredators. Small mammal wariness was associated with predator-prey body mass ratio, regardless of the nativity. The one thing animals do not seem to recognize is whether their predators are native.La hipótesis de la ingenuidad de la presa plantea que ésta es vulnerable a los depredadores introducidos porque se requiere que muchas generaciones atraviesen una coevolución lenta y gradual para que se desarrollen las respuestas de evasión adecuadas. La hipótesis supone que la presa será más sensible a los depredadores introducidos que difieren notoriamente de los nativos y de aquellos recién establecidos. Realizamos un metaanálisis global de estudios que midieron las respuestas cautelosas de mamíferos pequeños ante el rastro de meso depredadores simpátricos para probar estas suposiciones. Identificamos 26 estudios que cumplieron con nuestro criterio de selección. Estos estudios estuvieron conformados por 134 experimentos que reportaban las respuestas de 36 especies de mamíferos pequeños ante el rastro de seis meso depredadores introducidos y 12 nativos. Medimos la distancia funcional y filogenética entre cada meso depredador introducido y los meso depredadores locales nativos y el número de años simpátricos con su presa. Usamos la masa corporal del depredador y la presa como medida del riesgo de depredación. A nivel mundial, los mamíferos pequeños compartieron la cautela ante el rastro de los meso depredadores nativos e introducidos; la distancia funcional y la filogenética entre los meso depredadores introducidos y el meso depredador nativo más cercano no tuvieron efecto sobre la cautela; y la cautela no estuvo relacionada con el número de generaciones de la presa, o años, desde el primer contacto con los meso depredadores introducidos. La cautela de los mamíferos pequeños estuvo asociada con las proporciones de masa corporal entre el depredador y la presa, sin importar el origen. Lo único que los animales parecen no reconocer es si el depredador es nativo o no.猎物天真假说认为, 猎物容易受到外来捕食者的捕猎, 因为它们需要多个世代缓慢的共同进化才能恰当地躲避捕食者。该假说预测猎物对本地捕食者的反应比对外来捕食者的反应更强, 且对与本地捕食者和新出现捕食者差异较大的外来捕食者反应更弱。为了检验这些预测, 我们对全球小型哺乳动物对同域中型哺乳动物捕食者气味的警戒反应研究进行了荟萃分析。我们确定了 26 项符合筛选标准的研究, 包含报告了 36 种小型哺乳动物对 6 种外来中型捕食者和 12 种本地中型捕食者气味反应的 134 项实验。对于每一种外来中型捕食者, 我们测量了它们与本地中型捕食者的系统发育距离及功能距离, 及其与猎物同域分布的年数。我们还用捕食者和猎物的体重作为捕食风险的衡量标准。结果显示, 在全球范围内, 小型哺乳动物对本地和外来中型捕食者的气味具有相似的警惕性;外来中型捕食者与最接近的本地中型捕食者之间的系统发育距离及功能距离对警惕性没有影响;且警惕性与猎物和外来中型捕食者首次接触后的世代数或年数无关。小型哺乳动物的警惕性与捕食者-猎物的体重比有关, 而与捕食者是否为本地物种无关。由此可见, 动物似乎无法分辨捕食者是本地物种还是外来物种。【翻译:胡怡思;审校:聂永刚】.

Invasive species pose a significant threat to biodiversity and agriculture world-wide. Natural enemies play an important part in controlling pest populations, yet we understand very little about the presence and prevalence of natural enemies during the early invasion stages. Microbial natural enemies of fall armyworm Spodoptera frugiperda are known in its native region, however, they have not yet been identified in Africa where fall armyworm has been an invasive crop pest since 2016. Larval samples were screened from Malawi, Rwanda, Kenya, Zambia, Sudan and Ghana for the presence of four different microbial natural enemies; two nucleopolyhedroviruses, Spodoptera frugiperda NPV (SfMNPV) and Spodoptera exempta NPV (SpexNPV); the fungal pathogen Metarhizium rileyi; and the bacterium Wolbachia. This study aimed to identify which microbial pathogens are present in invasive fall armyworm, and determine the geographical, meteorological and temporal variables that influence prevalence. Within 3 years of arrival, fall armyworm was exposed to all four microbial natural enemies. SfMNPV probably arrived with fall armyworm from the Americas, but this is the first putative evidence of host spillover from Spodoptera exempta (African armyworm) to fall armyworm for the endemic pathogen SpexNPV and for Wolbachia. It is also the first confirmed incidence of M. rileyi infecting fall armyworm in Africa. Natural enemies were localised, with variation being observed both nationally and temporally. The prevalence of SfMNPV (the most common natural enemy) was predominantly explained by variables associated with the weather; declining with increasing rainfall and increasing with temperature. However, virus prevalence also increased as the growing season progressed. The infection of an invasive species with a natural enemy from its native range and novel pathogens specific to its new range has important consequences for understanding the population ecology of invasive species and insect–pathogen interactions. Additionally, while it is widely known that temporal and geographic factors affect insect populations, this study reveals that these are important in understanding the distribution of microbial natural enemies associated with invasive pests during the early stages of invasion, and provide baseline data for future studies.

Invasive red lionfish Pterois volitans (Linnaeus, 1758) represent an ongoing ecological threat within temperate and tropical waters. Relatively little is known regarding the overall health of P. volitans and their potential for spreading pathogens in non-native regions. Lionfish collected from inshore reefs of Grenada, West Indies, in 2019 and 2021 were identified as P. volitans based on cytochrome c oxidase subunit 1 barcoding. Gross and microscopic examination of tissues revealed myxozoan plasmodia in the hearts of 24/76 (31.6%) lionfish by histopathology or wet mount cytology. Further histopathologic examination revealed severe granulomatous inflammation and myofiber necrosis associated with developing plasmodia and presporogonic life stages. Fresh myxospores were morphologically and molecularly consistent with Kudoa hypoepicardialis, being quadrate in apical view with 4 valves and 4 equal polar capsules. The spore body was 5.1-7.9 (mean: 6.0) µm long, 8.1-9.8 (8.7) µm wide, and 6.9-8.5 (7.7) µm thick. Polar capsules were 2.3-2.7 (2.5) µm long and 0.9-1.6 (1.3) µm wide. 18S small subunit rDNA sequences were 99.81-99.87% similar to sequence data from the original description of the species. Novel 28S large subunit rDNA and elongation factor 2 data, which did not match any previously reported species, were provided. This is the first account of a myxozoan parasite of P. volitans, a new host record and locality for K. hypoepicardialis, and one of few reports describing pathogen-associated lesions in invasive lionfish.

Exploring how functional traits vary and covary is important to understand plant responses to environmental change. However, we have limited understanding of the ways multiple functional traits vary and covary within invasive species.We measured 12 leaf traits of an invasive plant Chromolaena odorata, associated with plant or leaf economics, herbivore defense, and drought resistance on 10 introduced populations from Asia and 12 native populations from South and Central America, selected across a broad range of climatic conditions, and grown in a common garden.Species' range and climatic conditions influenced leaf traits, but trait variation across climate space differed between the introduced and native ranges. Traits that confer defense against herbivores and drought resistance were associated with economic strategy, but the patterns differed by range. Plants from introduced populations that were at the fast-return end of the spectrum (high photosynthetic capacity) had high physical defense traits (high trichome density), whereas plants from native populations that were at the fast-return end of the spectrum had high drought escape traits (early leaf senescence and high percentage of withered shoots).Our results indicate that invasive plants can rapidly adapt to novel environmental conditions. Chromolaena odorata showed multiple different functional trait covariation patterns and clines in the native and introduced ranges. Our results emphasize that interaction between multiple traits or functions should be considered when investigating the adaptive evolution of invasive plants.

Digitized collections can help illuminate the mechanisms behind the establishment and spread of invasive plants. These databases provide a record of traits in space and time that allows for investigation of abiotic and biotic factors that influence invasive species.Over 1100 digitized herbarium records were examined to investigate the invasion history and trait variation of Microstegium vimineum. Presence-absence of awns was investigated to quantify geographic patterns of this polymorphic trait, which serves several functions in grasses, including diaspore burial and dispersal to germination sites. Floret traits were further quantified, and genomic analyses of contemporary samples were conducted to investigate the history of M. vimineum's introduction and spread into North America.Herbarium records revealed similar patterns of awn polymorphism in native and invaded ranges of M. vimineum, with awned forms predominating at higher latitudes and awnless forms at lower latitudes. Herbarium records and genomic data suggested initial introduction and spread of the awnless form in the southeastern United States, followed by a putative secondary invasion and spread of the awned form from eastern Pennsylvania. Awned forms have longer florets, and floret size varies significantly with latitude. There is evidence of a transition zone with short-awned specimens at mid-latitudes. Genomic analyses revealed two distinct clusters corresponding to awnless and awned forms, with evidence of admixture.Our results demonstrate the power of herbarium data to elucidate the invasion history of a problematic weed in North America and, together with genomic data, reveal a possible key trait in introduction success: presence or absence of an awn.

Invasive species tend to possess acquisitive plant traits that support fast growth and strong competitive ability. However, the relevance of symbioses with arbuscular mycorrhizal fungi (AMF) to the fast growing, acquisitive strategy of invasive species is still unclear.We measured AMF colonization in roots of five congeneric pairs of invasive and native eastern North American woody species (10 species total; 4 lianas, 6 shrubs) that were grown in a monoculture common garden experiment in Syracuse, NY. We then examined the relationships of AMF colonization to above and belowground traits of these species.Total AMF colonization and arbuscule colonization were greater in invasive compared to native woody species, a pattern that was more distinct in congeneric shrubs than congeneric lianas. The level of AMF colonization was also positively correlated with traits indicative of rapid plant growth and nutrient uptake.The concordance of a resource-acquisitive strategy with higher AMF colonization suggests that symbioses with AMF may be part of the strategy by which invasive woody plants of eastern North America are able to maintain fast growth rates and outcompete their native counterparts.

The data we present are part of the long-term project SLAM (Long Term Ecological Study of the Impacts of Climate Change in the natural forest of Azores) aiming to assess the impact of biodiversity erosion drivers on Azorean native biota, using long-term ecological data. Additionally to SLAM (Sea, Land and Air Malaise) traps, nocturnal Active Aerial Searching and nocturnal Foliage Beating methods were used to sample, between 2017 and 2018, the arthropod biodiversity on two historical urban gardens of Azores, the “Jardim Botânico” of Faial Island and “Jardim Duque da Terceira” of Terceira Island. We provided an inventory of arthropods collected between 2017 and 2018 in two urban gardens of Faial and Terceira Islands (Azores). A total of 8342 specimens were collected, in which 7493 specimens were identified to species/subspecies level (Faial n = 3296; Terceira n = 4197). The identified specimens belong to four classes, 15 orders, 80 families and 159 species and subspecies of arthropods. A total of 84 species and subspecies are considered introduced (n = 2454 specimens), 50 native non-endemic (n = 4444 specimens), eight endemic (n = 217) and 17 have an indeterminate origin (n = 378). This study also revises the arthropod inventory of these Azorean gardens, by adding/updating the taxonomic names of three orders, ten families and 22 species.

MDFRC item.Using fish data from an intensive radio-tracking study over three consecutive seasons of microhabitat interaction between introduced pumpkinseed Lepomis gibbosus and native brown trout Salmo trutta in an English stream, constrained additive (CAO) and quadratic ordination (CQO) were used as a novel analytical approach to determine the degree of overlap and repartition in seasonal microhabitat preference between the two species, and to assess the shape of their preference profiles across a microhabitat gradient defined by depth, velocity, substratum, macrophytes, shelters and debris. Both species showed preference for stream pool habitats with instream cover mostly irrespective of season, indicating the existence of a microhabitat overlap. However, a certain degree of microhabitat repartition also was evident, with narrower preference profiles for introduced pumpkinseed relative to native brown trout. Overall, CAO and CQO represent a logical and useful multivariate extension to available modelling approaches in fish-habitat studies due to their ability to provide for a synoptic representation of response profiles for different species over a composite (latent) variable describing (micro) habitat characteristics.

Established alien land snail species that were introduced into the Western Palaearctic Region from other regions and their spread in the Western Palaearctic are reviewed. Thirteen of the 22 species came from North America, three from Sub-Saharan Africa, two from the Australian region, three probably from the Oriental Region and one from South America. The establishment of outdoor populations of these species was usually first seen at the western or southern rims of the Western Palearctic. Within Europe, the alien species usually spread from south to north and from west to east. The latitudinal ranges of the alien species significantly increased with increasing time since the first record of introduction to the Western Palearctic. The latitudinal mid-points of the Western Palaearctic and native ranges of the species are significantly correlated when one outlier is omitted. There is a general trend of poleward shifts of the ranges of the species in the Western Palaearctic compared to their native ranges. There are three reasons for these shifts: (1) the northward expansion of some species in Western Europe facilitated by the oceanic climate, (2) the impediment to the colonisation of southern latitudes in the Western Palaearctic due to their aridity and (3) the establishment of tropical species in the Mediterranean and the Middle East. Most of the species are small, not carnivorous and unlikely to cause serious ecological or economic damage. In contrast, the recently introduced large veronicellid slugs from Sub-Saharan Africa and the giant African snail Lissachatina fulica could cause economic damage in irrigated agricultural areas or greenhouses in the Mediterranean and the Middle East.

The present study adds 19 species (15 Rhodophyta, one Chlorophyta and three Ochrophyta) to the Azorean marine macroalgal flora, increasing the current total of species recorded in this region to 521 (349 Rhodophyta, 76 Chlorophyta and 96 Ochrophyta), and showing that this isolated island group supports a relatively rich marine macroalgal flora. Some species fall within their known overall distributional range, whereas other found here represent a northern or southern extension to their known distribution in the Atlantic. Three species (Antithamnionella elegans, Gymnophycus hapsiphorus and Scytosiphon dotyi) are probable introductions to the Azores, whereas Melanothamnus pseudoforcipatus has an uncertain status. Six of the newly reported species were found as components of the intertidal algal turf samples, which justifies the need for continuing to examine turf samples as new discoveries can be anticipated. This study is a contribution to the project AZORESBIOPORTAL-PORBIOTA (ACORES-010145-FEDER-000072) funded through FEDER (85%) and Regional funds (15%) via Operational Programme Azores 2020. Funding was also provided from National Funds through FCT-Fundação para a Ciência e a Tecnologia, under the projects UID/BIA/00329/2013, 2015-2018 and UID/BIA/00329/2019 and UID/BIA/00329/2020-2023. EC benefitted from a post-doctoral fellowship awarded by ARDITI (Regional Agency for Development of Research, Technology and Innovation of Madeira, Project M1420-09-5369-FSE-000002). ACLP was supported by PhD grant awarded by FRCT-Fundo Regional da Ciência e Tecnologia (M3.1.a/F/083/2015). PDT was supported by Xunta de Galicia 'Axudas de apoio a etapa de formacion posdoutoral' (grant ED481D/2017/011) and `Talento Senior' (grant 03IN858A2019-1630129). info:eu-repo/semantics/publishedVersion

La mayoría de las especies de plantas introducidas en México no han sido evaluadas para priorizar las acciones de gestión para erradicarlas o contenerlas o para mitigar los daños causados por invasiones de plantas nocivas. Se evaluaron 42 taxa (41 especies y una variedad) de malezas introducidas de la familia Leguminosae usando criterios empíricos y derivados de teoría, en el desarrollo de un modelo centrado en el comportamiento de las especies en el extranjero, su tiempo de residencia y las localidades ocupadas, y la presencia en México de los parientes congenéricos nativos y no nativos. Los datos se obtuvieron a partir de fuentes bibliográficas y de la base de datos “Malezas Introducidas en México” que incluye información de 11 herbarios de México. También desarrollamos un proceso de puntuación para calificar la expansión de las introducidas de acuerdo con tiempo de residencia y número de localidades ocupadas. Clasificamos a las leguminosas introducidas en cuatro categorías de prioridad de atención. Albizia lebbeck, Pueraria phaseoloides, Lablab purpureus, Securigera varia, Delonix regia, Clitoria ternatea y Spartium junceum deben recibir prioridad de atención alta; consideramos que ocho especies requieren una atención prioritaria media, y siete atención prioritaria baja. 20 taxa fueron clasificados como no prioritarios. El modelo de evaluación desarrollado todavía necesita un mayor refinamiento, ya que especies aparentemente inocuas obtuvieron puntajes altos y una potencialmente peligrosa (Cassia fistula) se clasificó en la categoría no prioritaria. Esperamos que el presente modelo de evaluación funcionará como una herramienta y con baja dependencia de expertos, para identificar a las especies introducidas que requieren un análisis de riesgo más completo para priorizar esfuerzos para el manejo de las plantas introducidas nocivas.

Interference competition over food and territory can shape population structure and habitat use within and between species. The introduction of invasive species often leads to novel competitive interactions over shared resources and invaders can eventually exclude the native species from preferred habitats. Invasive brook trout (Salvelinus fontinalis) introduced to northern Europe have excluded native brown trout (Salmo trutta) from numerous headwater streams. The fact that invasive brook trout can displace the more aggressive brown trout is puzzling. However, the earlier spawning and hatching of brook trout, compared to brown trout, may lead to unequal competition due to size advantage and prior resident status of brook trout at the fry stage. In this study, we examine the effect of competition between brown trout and brook trout using the natural size distribution of the two species. In two consecutive experiments, we first measured space use and feeding of a fry (age 0+) in the presence of a juvenile (age 1+). In experiment 2, we assessed territorial interactions between the species at the fry stage (age 0+) and if smaller brown trout could compensate the disadvantage by manipulating residence duration. Fry of brook trout feed sooner and spend more time close to the larger individual than brown trout fry. We also found that brook trout fry won most territorial contests against brown trout, and that increased residence duration led to longer and more aggressive interactions. The results suggest that smaller brown trout are displaced to suboptimal habitats in the presence of a larger brook trout. Therefore, the later emergence from gravel beds resulting in the naturally occurring size disadvantage of brown trout at the fry stage may lead to unequal territorial interactions that could explain why brown trout are displaced from preferred habitats in sympatry with brook trout.

Prudent predators catch sufficient prey to sustain their populations but not as much as to undermine their populations' survival. The idea that predators evolve to be prudent has been dismissed in the 1970s, but the arguments invoked then are untenable in the light of modern evolution theory. The evolution of prudent predation has repeatedly been demonstrated in two-species predator-prey metacommunity models. However, the vigorous population fluctuations that these models predict are not widely observed. Here we show that in complex model food webs prudent predation evolves as a result of consumer-mediated ('apparent') competitive exclusion of resources, which disadvantages aggressive consumers and does not generate such fluctuations. We make testable predictions for empirical signatures of this mechanism and its outcomes. Then we discuss how these predictions are borne out across freshwater, marine and terrestrial ecosystems. Demonstrating explanatory power of evolved prudent predation well beyond the question of predator-prey coexistence, the predicted signatures explain unexpected declines of invasive alien species, the shape of stock-recruitment relations of fish, and the clearance rates of pelagic consumers across the latitudinal gradient and 15 orders of magnitude in body mass. Specific research to further test this theory is proposed.

Freshwater rivers and lakes are particularly vulnerable to anthropogenic disturbance because of their proximity to human occupation. Anthropogenic impacts in fresh water include those caused by dams, water pollution, channelization, and invasive species. One common action to conserve freshwater biodiversity involves supplementing or reintroducing extirpated species, though the benefits of these efforts are controversial. Installation of fishways to dams and removal of invasive alien species has also resulted in recovery of native species. Herein results of long-term monitoring of salmonids in two rivers in Japan are presented. The first case involves a river above a dam where native white-spotted charr Salvelinus leucomaenis and masu salmon Oncorhynchus masou declined rapidly in number following dam construction, where non-native rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta increased in number, and where stocking of native masu salmon was unsuccessful. The second case involves a river formerly dominated by non-native rainbow trout, in which native Dolly Varden charr Salvelinus curilus and masu salmon increased in numbers following removal of non-native species and fishway installation. Results reveal natural recovery of masu salmon in a river within which they were once completely extirpated, without stocking. Because salmonids are migratory fish and return to natal rivers, when locally extinct, human intervention to stock or reintroduce them has often been deemed necessary. However, restoration of wildlife would not require stocking or reintroduction if factors that impede the self-recovery capability of species are removed.

In this study we report the first case of an introduced alien host spider species being parasitized and manipulated by an ichneumonid wasp. Hymenoepimecis bicolor, previously described parasitizing exclusively Trichonephila clavipes (Araneidae), was observed parasitizing the European species Cyrtophora citricola (Araneidae) in southeastern Brazil. The cocoon web built by the parasitized spider is composed of a reduced horizontal sheet, which maintains the radial structure. The reduced number of radii and spirals probably reduce the chances of insect interception by these modified structures. In addition, the density of supporting threads is apparently very different between normal and modified webs. The cocoon web spun by C. citricola lacks the protective barrier structure usually observed in cocoon webs spun by parasitized females of T. clavipes. Our observations are in agreement with several predictions of the ecdysteroid hypothesis and represent an interesting opportunity for further investigation of interactions between these parasitoids and their spider hosts.

Biological invasions pose one of the most severe environmental challenges of the twenty-first century. A longstanding idea is that invasion risk is predictable based on the phylogenetic distance - and hence ecological resemblance - between non-native and native species. However, current evidence is contradictory. To explain these mixed results, it has been proposed that the effect is scale-dependent, with invasion inhibited by phylogenetic similarity at small spatial scales but enhanced at larger scales. Analyzing invasion outcomes in a global sample of bird communities, we find no evidence to support this hypothesis. Instead, our results suggest that invaders are locally more successful in the presence of closely related and ecologically similar species, at least in human-altered environments where the majority of invasions have occurred. Functional trait analyses further confirm that the ecological niches of invaders are phylogenetically conserved, supporting the notion that successful invasion in the presence of close relatives is driven by shared adaptations to the types of niches available in novel environments.

Globalization and intensified volume of trade and transport around the world are accelerating the rate of biological invasions. It is therefore increasingly important to understand the processes through which invasive species colonize new habitats, often to the detriment of native flora. The initial steps of an invasion are particularly critical, as the introduced species relies on limited genetic diversity to adapt to a new environment. However, our understanding of this critical stage of the invasion is currently limited. We used a citizen science approach and social media to survey the distribution of invasive sunflower in Israel. We then sampled and sequenced a representative collection and compared it with available genomic data sets of North American wild sunflower, landraces and cultivars. We show that invasive wild sunflower is rapidly establishing throughout Israel, probably from a single, recent introduction from Texas, while maintaining high genetic diversity through ongoing gene flow. Since its introduction, invasive sunflower has spread quickly to most regions, and differentiation was detected despite extensive gene flow between clusters. Our findings suggest that rapid spread followed by continuous gene flow between diverging populations can serve as an efficient mechanism for maintaining sufficient genetic diversity at the early stages of invasion, promoting rapid adaptation and establishment in the new territory.

During the Anthropocene, Earth has experienced unprecedented habitat loss, native species decline and global climate change. Concurrently, greater globalization is facilitating species movement, increasing the likelihood of alien species establishment and propagation. There is a great need to understand what influences a species’ ability to persist or perish within a new or changing environment. Examining genes that may be associated with a species’ invasion success or persistence informs invasive species management, assists with native species preservation and sheds light on important evolutionary mechanisms that occur in novel environments. This approach can be aided by coupling spatial and temporal investigations of evolutionary processes. Here we use the common starling, Sturnus vulgaris, to identify parallel and divergent evolutionary change between contemporary native and invasive range samples and their common ancestral population. To do this, we use reduced-representation sequencing of native samples collected recently in northwestern Europe and invasive samples from Australia, together with museum specimens sampled in the UK during the mid-19th century. We found evidence of parallel selection on both continents, possibly resulting from common global selective forces such as exposure to pollutants. We also identified divergent selection in these populations, which might be related to adaptive changes in response to the novel environment encountered in the introduced Australian range. Interestingly, signatures of selection are equally as common within both invasive and native range contemporary samples. Our results demonstrate the value of including historical samples in genetic studies of invasion and highlight the ongoing and occasionally parallel role of adaptation in both native and invasive ranges.

1. We studied the natural history knowledge (NHK) of students (18-19 years), considering the salience of nature expressed through the knowledge of names of organisms, routes for knowledge transmission and acquisition, and the potential of specific taxa to represent a student's overall knowledge. 2. We report a two-year study of the NHK of 149 UK-resident first-year biology students surveyed by means of a free-listing exercise, facilitating the assessment of salience, prior to participation in a residential field-course run by the University of Oxford. 3. Each year, students anonymously completed a questionnaire asking them to name any five species in each of five taxonomic groups (birds, trees, mammals, butterflies and wildflowers) found wild in the British Isles, also stating if those named were native or introduced. Metadata were collected on the students' background and sources of knowledge (e.g., family, teachers, etc.). 4. Of the five taxonomic groups, birds were the best known by the students, while butterflies were the most poorly known group. However, although asked for names at species level, while 94% of students could name five British bird taxa, only 55.7% named them at species level, many giving folk-generics such as ‘duck’ or ‘seagull’ instead. For butterflies, only 12.8% of students correctly named five British species, and 47% named none. 5. Family influences, self-motivation and knowledge of birds, rather than formal education, best predicted students’ overall NHK. While urban/rural residency had a small effect on NHK, it strongly influenced the relative importance of other factors. 6. Factor Analysis showed NHK was best represented by knowledge of birds. Furthermore, the bird species named predicted students’ total NHK as well as the students’ knowledge of birds. Asked to name their favourite bird, students with family influence were significantly more likely to name native species. 7. We describe the complex interplay between context, family and formal education in developing nature salience; roles which we define as nature ‘advocacy’. In the urban context, the advocacy of family and teachers was essential to engage young people with nature, while this was not so in a rural context. We briefly consider the implications of our study for natural history education going forward.

Successful control and prevention of biological invasions depend on identifying traits of non-native species that promote fitness advantages in competition with native species. Here, we show that, among 76 native and non-native woody plants of deciduous forests of North America, invaders express a unique functional syndrome that combines high metabolic rate with robust leaves of longer lifespan and a greater duration of annual carbon gain, behaviours enabled by seasonally plastic xylem structure and rapid production of thin roots. This trait combination was absent in all native species examined and suggests the success of forest invaders is driven by a novel resource-use strategy. Furthermore, two traits alone-annual leaf duration and nuclear DNA content-separated native and invasive species with 93% accuracy, supporting the use of functional traits in invader risk assessments. A trait syndrome reflecting both fast growth capacity and understorey persistence may be a key driver of forest invasions.

Hybridization plays an important and underappreciated role in shaping the evolutionary trajectories of species. Following the introduction of a non-native organism to a novel habitat, hybridization with a native congener may affect the probability of establishment of the introduced species. In most documented cases of hybridization between a native and a non-native species, a mosaic hybrid zone is formed, with hybridization occurring heterogeneously across the landscape. In contrast, most naturally occurring hybrid zones are clinal in structure. Here, we report on a long-term microsatellite data set that monitored hybridization between the invasive winter moth, Operophtera brumata (Lepidoptera: Geometridae), and the native Bruce spanworm, O. bruceata, over a 12-year period. Our results document one of the first examples of the real-time formation and geographic settling of a clinal hybrid zone. In addition, by comparing one transect in Massachusetts where extreme winter cold temperatures have been hypothesized to restrict the distribution of winter moth, and one in coastal Connecticut, where winter temperatures are moderated by Long Island Sound, we found that the location of the hybrid zone appeared to be independent of environmental variables and maintained under a tension model wherein the stability of the hybrid zone was constrained by population density, reduced hybrid fitness, and low dispersal rates. Documenting the formation of a contemporary clinal hybrid zone may provide important insights into the factors that shaped other well-established hybrid zones.

Understanding the mechanisms allowing invasive species to adapt to novel environments is a challenge in invasion biology. Many invaders demonstrate rapid evolution of behavioural traits involved in range expansion such as locomotor activity, exploration and risk-taking. However, the molecular mechanisms that underpin these changes are poorly understood. In 86 years, invasive cane toads (Rhinella marina) in Australia have drastically expanded their geographic range westward from coastal Queensland to Western Australia. During their range expansion, toads have undergone extensive phenotypic changes, particularly in behaviours that enhance the toads' dispersal ability. Common-garden experiments have shown that some changes in behavioural traits related to dispersal are heritable. At the molecular level, it is currently unknown whether these changes in dispersal-related behaviour are underlain by small or large differences in gene expression, nor is known the biological function of genes showing differential expression. Here, we used RNA-seq to gain a better understanding of the molecular mechanisms underlying dispersal-related behavioural changes. We compared the brain transcriptomes of toads from the Hawai'ian source population, as well as three distinct populations from across the Australian invasive range. We found markedly different gene expression profiles between the source population and Australian toads. By contrast, toads from across the Australian invasive range had very similar transcriptomic profiles. Yet, key genes with functions putatively related to dispersal behaviour showed differential expression between populations located at each end of the invasive range. These genes could play an important role in the behavioural changes characteristic of range expansion in Australian cane toads.

Human activity has facilitated the introduction of many exotic species via global trade. Asia-Pacific countries comprise one of the most economically and trade-active regions in the world, which makes it one of the most vulnerable regions to invasive species, including ants. There are currently over 60 exotic ant species in the Asia-Pacific, with the red imported fire ant, Solenopsis invicta, among the most destructive. Exotic ants pose many economic and ecological problems for the region. Countries in the Asia-Pacific have dealt with the problem of exotic ants in very different ways, and there has been an overall lack of preparedness. To improve the management of risks associated with invasive ants, we recommend that countries take action across the biosecurity spectrum, spanning prevention, containment, and quarantine. The creation of an Asia-Pacific network for management of invasive ants should help prevent their introduction and mitigate their impacts. Expected final online publication date for the Annual Review of Entomology, Volume 67 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Interspecific aggression has important fitness consequences across the animal kingdom and can be especially important during species invasions, where asymmetric interactions between native and invasive species can lead to native species declines. We investigated the immediate behavioural consequences of interspecific interactions for a native species, the green anole lizard, Anolis carolinensis, after an invasion by a closely related invasive species, the Cuban brown anole, Anolis sagrei. We housed captive populations of green anoles (6 males, 6 females) in large outdoor enclosures and recorded their display behaviours (displays/min), activity levels (movements/min) and habitat use (2D and 3D home range size, perch height) for 10 days. We then introduced brown anoles and recorded the green anoles' behaviours for another 10 days, seeking differences between pre- and post-invasion behaviours. We recorded behavioural interactions between individuals (i.e. headbob and dewlap displays, chases, mating attempts, fights and copulations) throughout the study. To serve as a density control, we duplicated the experiment in a second enclosure using green anoles as ‘invaders’. We performed the experiment eight times with two densities of invaders: high (4 males, 4 females) and low (2 males, 2 females). We found that green anoles have smaller two-dimensional and three-dimensional home ranges and higher average perch heights after invasions but that these changes resulted from increased population densities rather than aggression from brown anole invaders. Furthermore, although green and brown anoles did display to each other, both species preferentially interacted with conspecifics and escalated aggressive behaviours between the two species (e.g. lock-jawed fights) rarely occurred. Taken together, these findings indicate that high brown anole population densities, rather than direct interference competition, could be driving green anole displacement across the brown anole's invasive range.

Habitat disturbance can promote the invasion success of alien species, but the underlying mechanisms remain unclear, especially in animal species. Alien species may have trait values that facilitate invasion (ideal weed hypothesis) or greater phenotypic plasticity than native species (plasticity hypothesis), thus promoting their invasion success in disturbed habitats. Invasion success and ultimately alien species dominance in disturbed habitats can also be a direct consequence of competitive exclusion of native species. We performed experiments in controlled conditions to determine which of these mechanisms could explain the invasion success of Arion subfuscus s.l. (hereafter Arion), an alien slug species complex that lives in various disturbed ecosystems of eastern Canada such as managed forests. To do so, we compared the behavioural response of Arion and native sympatric philomycid slugs (hereafter Philomycus) to a decrease in soil moisture content, which often occurs after forest harvesting (i.e. habitat disturbance). We also investigated whether the presence of Arion alters the behaviour of Philomycus, which would indicate that Arion has a greater ability to compete by interference than these native species. Our findings show that Arion did not have higher boldness or locomotor activity (i.e. behaviours that promote invasion success) or greater plasticity than Philomycus, and that the presence of Arion did not affect the behaviour of Philomycus. However, Arion may be able to exploit resources more efficiently than native species since it mainly used the closest refuge from the food source in the present study. These findings are in line with the ideal weed hypothesis but do not support the phenotypic plasticity hypothesis or any role of interference competition in Arion invasion success in disturbed habitats such as harvested forests. Our results also suggest that the direction, but not the magnitude, of behavioural plasticity might be a key aspect in alien species invasion success in disturbed habitats.

Antarctica's isolation has been breached by various non-native species, including microbes, a grass, and some invertebrates. As yet, no marine species have reportedly established populations. With increasing effects of climate change and human activity, continued concerted action is needed to keep Antarctica protected from the impacts of non-native species establishment.

In Europe Callopistromyia annulipes Macquart, 1855 is an alien species. It was introduced from North America in 2007 and has spread to more than ten European countries. The spread of the species has been observed since 2007 and the trend isstill continuing, the species having recently been found in Croatia. Using social networks such as Facebook and iNaturalist, we can spot the spread of alien species to new areas, learn more about their ecology and speculate on the direction of potential expansion. Citizen science is an excellent tool for obtaining new knowledge, but as of today, its potentials are greatly underutilized.

Elton's biotic resistance hypothesis, which posits that diverse communities should be more resistant to biological invasions, has received considerable experimental support. However, it remains unclear whether such a negative diversity-invasibility relationship would persist under anthropogenic environmental change. By using the common ragweed (Ambrosia artemisiifolia) as a model invader, our 4-year grassland experiment demonstrated consistently negative relationships between resident species diversity and community invasibility, irrespective of nitrogen addition, a result further supported by a meta-analysis. Importantly, our experiment showed that plant diversity consistently resisted invasion simultaneously through increased resident biomass, increased trait dissimilarity among residents, and increased community-weighted means of resource-conservative traits that strongly resist invasion, pointing to the importance of both trait complementarity and sampling effects for invasion resistance even under resource enrichment. Our study provides unique evidence that considering species' functional traits can help further our understanding of biotic resistance to biological invasions in a changing environment.

La restauración de los pastizales naturales invadidos por especies vegetales exóticas depende de la composición del banco de semillas del suelo. Se analizó la composición del banco de semillas germinable del suelo en dos ambientes de la Reserva Natural Paititi (Buenos Aires, Argentina): pastizales de Paspalum quadrifarium Lam. (pastizal natural) y pastizales invadidos por árboles exóticos que no superaban los cinco años de edad, Racosperma melanoxylon (R. Br.) Pedley, sinónimo de Acacia melanoxylon (pastizal invadido). Se tomaron muestras de suelo de cada ambiente en tres sitios, y mediante el registro de la emergencia de plántulas bajo condiciones controladas se determinó: 1) la densidad del banco de semillas total y de los grupos funcionales (dicotiledóneas, gramíneas y graminoides), la riqueza, la equitatividad, la diversidad y la abundancia específica, 2) la disimilitud florística, y 3) el valor zootécnico. Ni el banco de semillas de las especies nativas ni el de las exóticas difirieron significativamente entre ambientes. La densidad promedio del banco de semillas y de la riqueza no fueron significativamente diferentes entre ambientes (~10000 semillas/m2 y 30 especies, respectivamente). El número de semillas de los grupos funcionales y los índices de diversidad y de equitatividad tampoco fueron significativamente diferentes entre ambientes. Sin embargo, la disimilitud florística fue 0.36 y se explica por la ausencia de un mayor número de especies en el pastizal invadido, entre ellas, las buenas forrajeras. Esto determinó un valor zootécnico 26% menor en el pastizal invadido que en el natural. En el pastizal invadido, todas las plantas de P. quadrifarium estaban muertas y su banco de semillas germinable fue casi un tercio que en el pastizal natural. Estos resultados permiten considerar que si se eliminan los árboles de R. melanoxylon del pastizal recientemente invadido se podría conservar un banco de semillas comparable al del pastizal natural. The restoration of natural grasslands invaded by exotic plant species depends on the composition of the soil seed bank. We analyzed the composition of germinable soil seed bank in two environments of the Paititi Natural Reserve (Buenos Aires, Argentina): Paspalum quadrifarium Lam. grasslands (natural grassland) and grasslands invaded by species of exotic trees that were no more than five years old, Racosperma melanoxylon (R. Br.) Pedley, synonymous Acacia melanoxylon (invaded grassland). Soil samples from each environment were taken at three sites, and by recording seedling emergence under controlled conditions we determined: 1) the total soil seed bank density of the functional groups (dicots, grasses and graminoids), richness, equitability and diversity indices, and specific abundance, 2) floristic dissimilarity, and 3) zootechnical value. The seed bank of native and exotic species was not significantly different between environments. Average seed bank density and species richness were not significantly different between environments (~10000 seeds/m² and 30 species, respectively). Seed density of the functional groups and the diversity and equitability indices were not significantly different between environments. Still, floristic dissimilarity among environments was as low as 0.36, explained by the absence of a greater number of species in the invaded grassland. The seed bank of invaded grasslands was poor in forage species, consistent with a zootechnical value 26% lower than in the natural grassland. In the invaded grassland all P. quadrifarium plants were dead and their germinable seed bank was a third than in the natural grassland. The results suggest that an early intervention removing R. melanoxylon trees in the grassland invaded may preserve a soil seed bank comparable to those uninvaded grassland. EEA Balcarce Fil: Vignolio, Osvaldo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Fil: Garavano, María Eugenia. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Fil: Diez de Ulzurrun, Patricia. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Fil: Angelini, Hernán Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina. Fil: Ispizúa, Verónica. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.

Lake Ontario boasts a diverse fish community comprised of native and introduced species that support vibrant recreational, commercial and Indigenous fisheries. The effective delivery of a program to assess and control the sea lamprey (Petromyzon marinus) is crucial to achievement of Lake Ontario Fish Community Objectives of rehabilitating native fish stocks while protecting and maintaining the abundance of introduced salmonines. During 2000–2019, the Great Lakes Fishery Commission (GLFC) and its control agents, Fisheries and Oceans Canada (DFO) and the U. S. Fish and Wildlife Service (USFWS), delivered a consistent program of sea lamprey assessment and control. Beginning in 2004, rising sea lamprey abundance and marking rates on lake trout (Salvelinus namaycush) in Lake Ontario coincided with a decline of large lake trout in gillnet surveys. Efforts were undertaken to identify and control important sources of juvenile sea lampreys, including larvae that survived treatment, inhabited deepwater areas, or colonised previously uninhabited stream reaches and tributaries. A renewed reliance on proven conventional controls, including lampricide treatments and barriers, has resulted in consistent suppression of sea lamprey abundance and lake trout marking to prescribed targets in Lake Ontario during 2014–2019. This achievement is unprecedented in the 49-year history of Sea Lamprey Control Program delivery in Lake Ontario, and is attributable to the collaborative efforts of the GLFC, the control agents, and federal, provincial, state, and Indigenous partners.

During the early stage of biological invasions, interactions occur between native and non-native species that do not share an evolutionary history. This can result in ecological naïveté, causing native species to exhibit maladaptive behavioural responses to novel enemies, leading to negative consequences for individual fitness and ecosystem function. The behavioural response of native to non-native species during novel encounters can determine the impact of non-native species, and restrict or facilitate their establishment. In this study we simulated novel encounters between a widespread invasive fish species, the Nile tilapia (Oreochromis niloticus), and a threatened native Manyara tilapia (Oreochromis amphimelas). In the first experiment single adult O. niloticus were presented with a stimulus chamber (a transparent plastic cylinder) which was empty during control trials and contained a pair of juvenile O. amphimelas in stimulus trials. In the second experiment, the reciprocal set up was used, with pairs of juvenile O. amphimelas as the focal species and adult O. niloticus as the stimulus. Both species approached the stimulus chamber more readily during stimulus trials, a behavioural response which would increase the prevalence of interspecific interactions in situ. This included physical aggression, observed from the competitively dominant O. niloticus towards O. amphimelas. Despite an initial lack of fear shown by O. amphimelas, close inspection of the stimulus chamber often resulted in an energetically costly dart response. Under field conditions we predict that naïve native individuals may readily approach O. niloticus, increasing the likelihood of interactions and exacerbating widely reported negative outcomes.

Temperature is one of the most important factors governing the activity of ectothermic species, and it plays an important but less studied role in the manifestation of invasive species impacts. In this study, we investigated temperature-specific feeding and metabolic rates of invasive and native crayfish, and evaluated how temperature regulates their ecological impacts at present and in future according to different climatic scenarios by bioenergetics modelling. We conducted a series of maximum food consumption experiments and measured the metabolic rates of cold-adapted native noble crayfish (Astacus astacus) and invasive signal crayfish (Pacifastacus leniusculus) originally from a warmer environment over a temperature gradient resembling natural temperatures in Finland. The maximum feeding rates and routine metabolic rates (RMR) of native noble crayfish were significantly higher at low temperatures (

Invasions by multiple nonnative species threaten native communities worldwide. We know that interactions among nonnative species influence nonnative success. However, we know relatively less about the influence of community assembly history on the interactions within nonnative species and thereby invasion success. To investigate this, we transplanted seedlings of two highly invasive shrubs, Rosa rubiginosa (hereafter ‘rose’) and Cytisus scoparius (hereafter ‘broom’), at two different times into mesocosm communities of native and nonnative species. We conducted priority and delay treatments that consisted of the early and late arrival of the invasive shrubs, respectively. We gave full priority/delay to each invasive shrub (rose early/late arrival, broom early/late arrival) and simultaneous priority/delay (simultaneous early/late arrival). We predicted that if assembly history were important, the invasive shrubs will benefit from early-arriving and will be disadvantaged by late-arriving and that arriving before the co-invader shrub will be more beneficial than arriving before the rest of the community. We also predicted that assembly history treatments that gave an advantage to invasive shrubs will more negatively affect native species than nonnative species. We found that the invasive shrubs did not benefit by early-arrival, but they were hindered by the early-arrival of the co-invader. The rose paid a high cost for late-arrival, but the broom was only impaired when its late-arrival implied arriving after the rose. Contrary to our predictions, natives paid a lower cost than nonnatives by arriving late. In general, our mesocosm experiment showed that the success of invasive species depended more on not arriving later than other invaders than on arriving early in the community. We suggest that community assembly history modulates the sign and strength of nonnative species interactions whose consideration might improve management practices.

An invasive foraminiferan is recorded for the first time in an Australian estuary. Trochammina hadai, originally described as endemic from Japan and subsequently found to be alien in coastal waters of California and Brazil, has been identified in estuarine sediment in the vicinity of Bunbury Port in Western Australia. Species determination is based on morphological, molecular and ecological similarities to the Japanese type. The species has not been recorded in other estuaries in Australia. Bunbury Port is a major exporter of woodchip to Japan and the introduction of T. hadai may have come from ballast water out of shallow-draught woodchip vessels. Small sediment samples of estuarine mud obtained at water depths of ~5 m contain abundant T. hadai (on average ~0.4 mm in adult diameter) that are easily recognised in microscopic view of the sediment surface by their bright reddish-brown colour. The collection of sediment samples from the estuarine floor and ballast water, and the examination of these for foraminifers, may provide a useful indicator in estuaries for the possible presence of other exotic species, particularly in the vicinity of ports.

Established non-native species can have significant impacts on native biodiversity without any possibility of complete eradication. In such cases, one management approach is functional eradication, the reduction of introduced species density below levels that cause unacceptable effects on the native community. Functional eradication may be particularly effective for species with limited dispersal ability, which may limit rates of reinvasion from distant populations. Here, we evaluate the potential for functional eradication of introduced predatory oyster drills (Urosalpinx cinerea) using a community science approach in San Francisco Bay. We combined observational surveys, targeted removals, and a caging experiment to evaluate the effectiveness of this approach in mitigating the mortality of prey Olympia oysters (Ostrea lurida), a conservation and restoration priority species. Despite the efforts of over 300 volunteers that removed over 30,000 oyster drills, we report limited success and discuss several possible mechanisms for this result with broad relevance to management for this and other introduced species. We also found a strong negative relationship between oyster drills and oysters, showing virtually no coexistence across eight sites. At two removal sites, there was no effect of oyster drill removal on oyster survival, which was only observed by caging treatment (0 and 1.6% survival in open and partial cage treatments, as compared to 89.1% in predator exclusion treatments). We conclude that functional eradication of this species requires significantly greater effort and may not be a viable management strategy. Oyster restoration efforts should not be undertaken where Urosalpinx is established or is likely to invade.

The introduction of invasive exotic species can have strong ecological impacts on the native biota, with direct consequences for commercial fisheries. Feeding ecology studies are among the primary sources for improving predictions related to community structures, for example, by revealing potential competitive interactions between native and invasive species. We compared the stomach contents and studied diet overlaps among a native (Mullus barbatus) and two invasive (Upeneus moluccensis and U. pori) mullid species, collected off the coasts of the northeastern Levantine where invasive mullids have been part of the ecosystem for more than half a century. We also assessed the effect of sex, sampling period, depth and size on stomach contents. Schoener’s index indicated significant diet overlaps between U. moluccensis–U. pori and U. moluccensis–M. barbatus. Diets of U. pori and M. barbatus did not significantly overlap, which was explained by their differing depth preferences. Assessment of stomach contents showed that Crustacea, specifically Decapoda, was the main prey group across the studied mullid species. Polychaeta was also of high importance in the diet of the native M. barbatus, but not for the two invasive Upeneus species. A trophic level analysis revealed the two invasive mullids to have a higher trophic level than the native species (U. moluccensis: 3.58, U. pori: 3.55 versus M. barbatus: 3.38). The lack of a clear separation in habitat and diet preferences documented here between native and invasive mullids may pose a risk for the persistence of the economically valuable native M. barbatus in the Mediterranean Sea.

Our study assessed the effectiveness of species debarking in controlling species invasion and the change in seedling dynamics after application of the different treatments. A split plots design was used in two forest reserves to assess the effectiveness of three debarking treatments: complete ring debarking, partial ring debarking and a control (no debarking). The results reveal that ring debarking has the potential to be used to control invasive species such as Cecropia peltata L. and Broussonetia papyrifera (L.) Vent. The efficiency, however, was influenced by the extent of the wound created and the size of tree, especially if trees are partially debarked. The control method also stimulated natural regeneration of native species with higher regeneration of native species recorded compared to invasive species. Also, plots that had completely debarked trees had higher species diversity than the partially debarked and the control plots in one of the reserve. The fact that none of the trees in the control plots died is indication of the effectiveness of debarking in the control of invasive species considered here. The effectiveness of this method suggests it is a suitable option for killing small to medium size trees with little cost to the environment compared to the application of arboricides for instance and is therefore worth revisiting in silvicultural treatments where minimum environmental disturbance is required. We recommend more studies to compare the effectiveness of the control approaches on different invasive species and monitor how the native communities respond including in terms of species diversity and functional groups, since removal methods may impact differently on these plant community traits.

The pine wood nematode (PWN), Bursaphelenchus xylophilus, is a destructive invasive species that exerts devastating effects on most native pines in invaded regions, while many of the non-native pines have resistance to PWN. Recently, increasingly more research is focused on how microbial communities can improve host resistance against pathogens. However, the relationship between the microbial community structures and varying levels of pathogen resistance observed in different pine tree species remains unclear. Here, the bacterial and fungal communities of introduced resistant pines Pinus elliottii, P. caribaea, and P. taeda and native susceptible pines healthy and wilted P. massoniana infected by PWN were analyzed. The results showed that 6057 bacterial and 3931 fungal OTUs were annotated. The pine samples shared 944 bacterial OTUs primarily in the phyla Proteobacteria, Acidobacteria, Firmicutes, Bacteroidetes, and Chloroflexi and 111 fungal OTUs primarily in phyla Ascomycota and Basidiomycota, though different pines had unique OTUs. There were significant differences in microbial community diversity between different pines, especially between the bacterial communities of resistant and susceptible pines, and fungal communities between healthy pines (resistant pines included) and the wilted P. massoniana. Resistant pines had a greater abundance of bacteria in the genera Acidothermus (class unidentified_Actinobacteria) and Prevotellaceae (class Alphaproteobacteria), but a lower abundance of Erwinia (class Gammaproteobacteria). Healthy pines had a higher fungal abundance of Cladosporium (class Dothideomycetes) and class Eurotiomycetes, but a lower abundance of Graphilbum, Sporothrix, Geosmithia (class Sordariomycetes), and Cryptoporus (classes Agaricomycetes and Saccharomycetes). These differences in microbial abundance between resistant and healthy pines might be associated with pathogen resistance of the pines, and the results of this study contribute to the studies exploring microbial-based control of PWN.