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Invasive species are characterized by their ability to colonize new habitats and establish populations away from their native range. In this sense, these plants are expected to have plastic responses to adapt to the environmental pressures during the invasion process. Hence, the role of natural selection is essential because it might favor the occurrence of advantageous traits. However, gene flow can counteract natural selection because immigrants introduce genes adapted to different conditions, with these introductions tending to homogenize allelic frequencies. In this work, we explore the effect of natural selection in invasive populations of S. madagascariensis in Argentina. We quantified leaf area, head number, and length of internodes and inflorescence from material spanning 54 years (1962-2016) and then compared between the edge versus established ranges. Our results show differences in all the measured plant traits among the sampled areas. However, only leaf area was statistically significant, which evidences different responses under the same environmental pressures in the areas located in the edge and established ranges. On the other hand, unlike homogeneous areas, the areas characterized by phenotypically diverse individuals were related to higher dispersal ability. In this sense, long-distance dispersal between neighboring areas may have had an important role in the recorded values. Furthermore, the implications of natural selection and founder effect in the invasion of S. madagascariensis are discussed.

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Spearfishing is currently the primary approach for removing invasive lionfish (Pterois volitans/miles) to mitigate their impacts on western Atlantic marine ecosystems, but a substantial portion of lionfish spawning biomass is beyond the depth limits of SCUBA divers. Innovative technologies may offer a means to target deepwater populations and allow for the development of a lionfish trap fishery, but the removal efficiency and potential environmental impacts of lionfish traps have not been evaluated. We tested a collapsible, non-containment trap (the 'Gittings trap') near artificial reefs in the northern Gulf of Mexico. A total of 327 lionfish and 28 native fish (four were species protected with regulations) recruited (i.e., were observed within the trap footprint at the time of retrieval) to traps during 82 trap sets, catching 144 lionfish and 29 native fish (one more than recruited, indicating detection error). Lionfish recruitment was highest for single (versus paired) traps deployed <15 m from reefs with a 1-day soak time, for which mean lionfish and native fish recruitment per trap were approximately 5 and 0.1, respectively. Lionfish from traps were an average of 19 mm or 62 grams larger than those caught spearfishing. Community impacts from Gittings traps appeared minimal given that recruitment rates were >10X higher for lionfish than native fishes and that traps did not move on the bottom during two major storm events, although further testing will be necessary to test trap movement with surface floats. Additional research should also focus on design and operational modifications to improve Gittings trap deployment success (68% successfully opened on the seabed) and reduce lionfish escapement (56% escaped from traps upon retrieval). While removal efficiency for lionfish demonstrated by traps (12-24%) was far below that of spearfishing, Gittings traps appear suitable for future development and testing on deepwater natural reefs, which constitute >90% of the region's reef habitat.

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The intensive use of glyphosate in industrial agriculture may lead to freshwater contamination, encouraging studies of its toxic effect on non-target aquatic organisms. Glyphosate-based commercial formulations contain adjuvants, making them even more toxic than the active ingredient (a.i.) itself. The golden mussel Limnoperna fortunei is a freshwater invasive species which has been found to increase glyphosate dissipation in water and to accelerate eutrophication. The aim of this study is to evaluate the capability of L. fortunei to reduce the concentration of glyphosate in two commercial formulations, Roundup Max® and Glifosato Atanor®. Results were compared with the decay of the a.i. alone and in presence of mussels. Evasive response and toxicity tests were performed in a first set of trials to analyze the response of L. fortunei exposed to Roundup Max® and Glifosato Atanor®. Subsequently, we conducted a 21-day degradation experiment in 2.6-L microcosms applying the following treatments: 6 mg L-1 of technical-grade glyphosate (G), Glifosato Atanor® (A), Roundup Max® (R), 20 mussels in dechlorinated tap water (M), and the combination of mussels and herbicide either in the technical-grade (MG) or formulated form (MA and MR) (all by triplicate). Samples were collected at days 0, 1, 7, 14 and 21. No significant differences in glyphosate decay were found between treatments with mussels (MG: 2.03 ± 0.40 mg L-1; MA: 1.60 ± 0.32 mg L-1; MR: 1.81 ± 0.21 mg L-1), between glyphosate as a.i. and the commercial formulations, and between the commercial formulations, suggesting that the adjuvants did not affect the degrading potential of L. fortunei. In addition to the acceleration of glyphosate dissipation in water, there was an increase in the concentration of dissolved nutrients in water (N-NH4+ and P-PO43-) even higher than that caused by the filtering activity of the mussels, probably resulting from stress or from the degradation of glyphosate and adjuvants. We believe that a larger bioavailability of these nutrients due to glyphosate metabolization mediated by mussels would accelerate eutrophication processes in natural water bodies. The approach used here, where L. fortunei was exposed to two commercial formulations actually used in agricultural practices, sheds light on the potential impact of glyphosate decay on water bodies invaded by this species.

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Quantifying the presence and environmental impact of invasive species is the starting point for research on management and nature conservation. North American beavers (Castor canadensis) were introduced to Argentina from Canada in 1946, and the species has been identified as a major agent of environmental change in the Tierra del Fuego archipelago in the Anthropocene. We studied the invasion status (distribution and density) of beavers through analyses of the dam densities in the Tierra del Fuego landscapes. We identified beaver dams with a GIS using visual interpretation of high-resolution aerial imagery from Microsoft Bing, Google Earth and HERE and related them to natural environmental gradients. These factors comprised geographic (vegetation zones and distance to streams), climatic (temperature, precipitation, evapotranspiration and net primary productivity) and topographic (elevation and slope) data. The datasets (dams and factors) were combined, and the data from the different zonation classes were subsequently compared using ANOVAs and Tukey's mean comparison tests. Deviations from the mean density (x mean density-x total mean density) were calculated to visualize the deviations for the studied factors. The datasets were also evaluated using principal component analyses (PCA). Our results showed a total of 206,203 beaver dams (100,951 in Argentina and 105,252 in Chile) in the study area (73,000 km2). The main island of Tierra del Fuego presented a greater degree of invasion (73.6% of the total study area) than the rest of the archipelago, especially in areas covered by mixed-evergreen and deciduous forests. The studied geographic, climatic and topographic factors showed positive trends (higher beaver preference) with beaver spread, which were all significant (p <0.05) when compared across the landscape. Although beavers are flexible in their habitat use, our empirical records showed that they had marked preferences and were positively influenced by the most productive forests. Here, we describe a scientific panorama that identified the drivers of species invasion based on satellite data and the available ecological datasets. The identification of such drivers could be useful for developing new tools for management and/or control strategies of the beavers in the Tierra del Fuego archipelago.

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Una de las causas que aportan a la disminución de la biodiversidad es la introducción de especies exóticas que muchas veces terminan siendo invasoras, y por lo tanto terminan compitiendo con especies locales. Esta competencia no siempre es equitativa ya que las especies invasoras comúnmente cuentan con ventajas adaptativas que le otorgan beneficios ante las especies locales. Este estudio realizado en microcuencas del noroccidente del Ecuador identifica los efectos de la reciente presencia de Poecilia gillii sobre la especie nativa Pseudopoecilia fria; mediante un análisis poblacional (distribución longitudinal, parámetros de crecimiento y morfometría). Los resultados muestran un desplazamiento de P. fria hacia la parte alta del río, un aceleramiento en su crecimiento y por lo tanto una madurez anticipada con la consecuente disminución del tamaño corporal y finalmente un cambio en el alto del cuerpo con deslizamiento posterior de la aleta pectoral.

One of the causes contributing to the decrease of biodiversity is the introduction of exotic species that often end up being invasive, and end up competing with local species. This competition is not always "fair" since invaders commonly have adaptive advantages that give them an advantage over local species. This study was carried out in small watersheds in northwestern Ecuador and identifies the effects of the recent introduction of P. gillii on the native species P. fria; using population analysis (longitudinal distribution, growth parameters and morphometry). The results show a displacement of P. fria towards the upper part of the river, acceleration in its growth and therefore an earlier sexual maturity with a consequent decrease in body size and finally a change in body depth with posterior displacement of the pectoral fin.

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In an era of climate change, biological invasions by alien species represent one of the main anthropogenic drivers of global environmental change. The present study, using an ensemble modelling approach, has mapped current and future global distribution of the invasive Leucanthemum vulgare (Ox-eye Daisy) and predicted the invasion hotspots under climate change. The current potential distribution of Ox-eye Daisy coincides well with the actual distribution records, thereby indicating robustness of our model. The model predicted a global increase in the suitable habitat for the potential invasion of this species under climate change. Oceania was shown to be the high-risk region to the potential invasion of this species under both current and future climate change scenarios. The results revealed niche conservatism for Australia and Northern America, but contrastingly a niche shift for Africa, Asia, Oceania and Southern America. The global distribution modelling and risk assessment of Ox-eye Daisy has immediate implications in mitigating its invasion impacts under climate change, as well as predicting the global invasion hotspots and developing region-specific invasion management strategies. Interestingly, the contrasting patterns of niche dynamics shown by this invasive plant species provide novel insights towards disentangling the different operative mechanisms underlying the process of biological invasions at the global scale.

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BACKGROUND: The insect Bagrada hilaris (Burmeister) an important pest worldwide, mainly due to the serious economic losses incurred and the large number of zones invaded. However, current and future spatial distributions of this pest, and the total area of cropland potentially affected have not been estimated. Here, we aim to: (1) estimate the potential geographic distribution of B. hilaris; (2) quantify the total area of cropland potentially affected worldwide, and in two recently colonized zones (California and Chile); and (3) estimate future changes in distribution under different climate change scenarios. RESULTS: We found that B. hilaris shows high environmental suitability in Mediterranean and arid regions, potentially affecting 1 108 184.1 km2 of cropland worldwide. The most affected continents were Asia and America, with 309 659.8 and 294 638.6 km2 of cropland at risk. More than 50% of cropland areas are at risk in seven countries. In California and central Chile, 43.7% and 50% of susceptible crops are at a high level of risk, respectively. Climate change scenarios predict an increase in the potential distribution of B. hilaris worldwide; America being the most affected continent. CONCLUSIONS: Our results provide a spatially explicit baseline from which to focus efforts on the prevention, management and control of this pest worldwide. © 2018 Society of Chemical Industry.

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Some marine invertebrates can inhabit floating substrates, and raft over long distances, becoming a significant environmental problem in terms of alien species and habitat disruption. On the Atlantico Department beaches (Colombia) woody debris and plastic litter dominate (86%) the types of refuse on the beaches with their densities ranging from 0.82-1.72 items m-1. Such litter and woody debris generate the optimal conditions for floating colonizers. In this work, 26 beaches were surveyed, and 16 of them (62%) were found to have marine fauna using litter and woody debris as a substrate for potential rafting and dispersal. Serpulidae polychaete tubes, goose barnacles Lepas (Anatifa) anserifera Linnaeus, 1767, and the bryozoans Arbopercula tenella (Hincks, 1880), Arbopercula angulata (Levinsen, 1909), plus three unidentified species were found colonizing woody debris, seeds, plastic and glass bottles. These findings of woody debris and litter facilitating the arrival and dispersal of non-native species on this coast, demonstrate that preventive management of such refuse in coastal habitats goes beyond simply preserving coastal esthetics.

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Alien species, one of the biggest threats to natural ecosystems worldwide, are of particular concern for oceanic archipelagos such as Galápagos. To enable more effective management of alien species, we reviewed, collated and analysed all available records of alien species for Galápagos. We also assembled a comprehensive dataset on pathways to and among the Galápagos Islands, including tourist and resident numbers, tourist vessels, their itineraries and visitation sites, aircraft capacity and occupancy, air and sea cargo and biosecurity interceptions. So far, 1,579 alien terrestrial and marine species have been introduced to Galápagos by humans. Of these, 1,476 have become established. Almost half of these were intentional introductions, mostly of plants. Most unintentional introductions arrived on plants and plant associated material, followed by transport vehicles, and commodities (in particular fruit and vegetables). The number, frequency and geographic origin of pathways for the arrival and dispersal of alien species to and within Galápagos have increased over time, tracking closely the increase in human population (residents and tourists) on the islands. Intentional introductions of alien species should decline as biosecurity is strengthened but there is a danger that unintentional introductions will increase further as tourism on Galápagos expands. This unique world heritage site will only retain its biodiversity values if the pathways for invasion are managed effectively.

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