Abandoned Foreigners: is the stage set for exotic pet reptiles to invade Central Europe?

Considerable scientific, politic and economic attention has been directed to biological invasions. Multiple pathways serve to introduce species to new environments and the release or escape of pets are among the most important sources for species invasions. Risk assessments help to identify species that are likely to become invasive and to set up preventive measures. Weighing the relative importance of ecological and human factors driving the establishment success of abandoned pets, we here present a new methodological guideline to help prioritising management activities for frequently traded pet reptiles. Climate match scores between the different distribution ranges as well as traits and niche axes shared by native and non-native species were assessed. Moreover, we tested for discrepancies in niche breadth between native and non-native ranges and estimated the ability of species to coexist with humans. Potentially moderate to high establishment success in most species was linked to appropriate climate match scores, broader niches with restrained human impacts and high similarities in reproductive traits with the native herpetofauna. Providing baseline information on the invasion potential of pet reptiles, this assessment calls for trade regulations and, to an even greater degree, for large scale education campaigns to prevent the establishment of non-native populations.     

Protected areas offer refuge from invasive species spreading under climate change

Protected areas (PAs) are intended to provide native biodiversity and habitats with a refuge against the impacts of global change, particularly acting as natural filters against biological invasions. In practice, however, it is unknown how effective PAs will be in shielding native species from invasions under projected climate change. Here, we investigate the current and future potential distributions of 100 of the most invasive terrestrial, freshwater, and marine species in Europe. We use this information to evaluate the combined threat posed by climate change and invasions to existing PAs and the most susceptible species they shelter. We found that only a quarter of Europe's marine and terrestrial areas protected over the last 100 years have been colonized by any of the invaders investigated, despite offering climatically suitable conditions for invasion. In addition, hotspots of invasive species and the most susceptible native species to their establishment do not match at large continental scales. Furthermore, the predicted richness of invaders is 11%–18% significantly lower inside PAs than outside them. Invasive species are rare in long‐established national parks and nature reserves, which are actively protected and often located in remote and pristine regions with very low human density. In contrast, the richness of invasive species is high in the more recently designated Natura 2000 sites, which are subject to high human accessibility. This situation may change in the future, since our models anticipate important shifts in species ranges toward the north and east of Europe at unprecedented rates of 14–55 km/decade, depending on taxonomic group and scenario. This may seriously compromise the conservation of biodiversity and ecosystem services. This study is the first comprehensive assessment of the resistance that PAs provide against biological invasions and climate change on a continental scale and illustrates their strategic value in safeguarding native biodiversity.     

Invasive fountain grass (Pennisetum setaceum (Forssk.) Chiov.) increases its potential area of distribution in Tenerife island under future climatic scenarios

Mapping the distribution of invasive species under current and future climate conditions is crucial to implement sustainable and effective conservation strategies. Several studies showed how invasive species may benefit from climate change fostering their invasion rate and, consequently, affecting the native species community. In the Canary Islands and on Tenerife in particular, previous research mostly focused on climate change impacts on the native communities, whereas less attention has been paid on alien species distribution under climate change scenarios. In this study, we modelled the habitat distribution of Pennisetum setaceum, one of the most invasive alien species on Tenerife. In addition, we described the species’ potential distribution shift in the light of two climate change scenarios (RCP2.6, RCP8.5), highlighting the areas that should be prioritized during management and eradication programs. P. setaceum’s suitable areas are located in the coastal area, with higher habitat suitability near cities and below 800 m asl. In both future climate change scenarios, the geographic distribution of P. setaceum suitable areas is characterized by an elevational shift, which is more pronounced in the RCP8.5 scenario. Despite being drought resistant, water supply is crucial for the species’ seed germination, thus supporting future species’ shift to higher elevation and in the north–north–west part of the island, where it could benefit from the combined effect of orographic precipitations and humidity carried by trade winds.

     

Casuarina: biogeography and ecology of an important tree genus in a changing world

Important insights on the invasion ecology of woody plants are emerging from the study of model groups, but it is important to test how widely such results can be generalised. We examined whether drivers of introduction and invasion in the genus Casuarina are similar to those identified for other groups. We reviewed the literature, mapped current global distributions, and modelled the potential global distribution of the genus. We assessed the rationale behind introductions, impacts of invasions, and the evolution of management approaches. Casuarinas have been introduced to about 150 countries. Ten of the 14 species in the genus have been introduced outside their native ranges, but only three species are recorded as naturalized or invasive (C. equisetifolia, C. cunninghamiana and C. glauca). Species with large native ranges are more likely to be introduced, and the three invasive species have the largest native ranges and the most records of introduction. There were no clear relationships between life-history traits (e.g. seed mass, plant height, or resprouting ability) and the extent of invasion. About 8 % of the Earth’s land surface is potentially suitable for casuarinas and large-scale plantings in some climatically suitable areas have not yet resulted in large-scale invasions; there is a substantial global Casuarina invasion debt. Experiences in Florida and the Mascarene Islands highlight that casuarinas have the potential to transform ecosystems with significant control costs. The challenge is to develop management approaches that minimise the impacts of invasions while preserving economic, environmental and cultural values of species in their introduced ranges.     

Niche dynamics of two cryptic <Emphasis Type="Italic">Prosopis</Emphasis> invading South American drylands

Whether or not species track native climatic conditions during invasions (i.e., climate match hypothesis) is fundamental to understand and prevent potential impacts of invasive species. Recent empirical work suggests that climatic mismatches between native and invasive ranges are pervasive. Whether these differences are due to adaptation to new climatic spaces in the invasive range or due to partial filling of the potential climatic space are still subject to debate. Here, we analyze climatic niche dynamics associated with the invasion of the two most common invasive plants in Brazilian semi-arid areas, Prosopis juliflora and Prosopis pallida. These species have been simultaneously introduced in the region, which creates a unique opportunity to compare their niche dynamics during invasion. Given that P. juliflora have a much wider native range size, we expect these species would present different dispersal potentials, which might translate into different unfilling levels. Using an ordination method with kernel smoother and null models, we contrasted climate spaces occupied by each species in both native and invasive ranges. We further used ecological niche models (ENMs) to compare reciprocal predictions of potentially suitable areas. Against our expectation based on differences in native range sizes, climatic niches of P. juliflora and P. pallida overlapped greatly, both in their native and invasive ranges. Our results support niche conservatism during the invasion process. Climatic mismatches among native and invaded ranges were exclusively attributed to unfilling of native climates in the invasive range. Both species showed similar unfilling levels. Likewise, ENMs predicted regions not yet occupied in the invasive range, revealing a potential for further expansion. We discuss colonization time lag and founder effect as potential mechanisms that may have prevented these species to fully occupy their native niches in the invasive range.     

Going Cheap: Determinants of Bird Price in the Taiwanese Pet Market

BackgroundInternational wildlife trade is the largest emerging source of vertebrate invasive alien species. In order to prevent invasions, it is essential to understand the mechanics of trade and, in particular, which traded species are most likely to be released or escape into the wild. A species’ economic value is a key factor, because we expect cheaper species to be less assiduously secured against escaping, and more likely to be deliberately released. Here, we investigate determinants of the price of species in the Taiwanese bird trade. Taiwan is an international hub for bird trade, and several native species are threatened by alien bird species.MethodologyWe investigated the relationship between the traded species sale price in Taiwan and the species availability for trade (the number of birds for sale, geographic range size and their origin, conservation and CITES status) and traits (body size, coloration, song attractiveness). We used phylogenetic generalized least squares models, with multi-model inference, to assess the variables that are best related to the price of birds in the Taiwanese pet trade.

Principal Findings / Conclusions

We found that species available for sale in larger numbers, native to Taiwan, not globally endangered, and small-bodied are all relatively cheaper, as too are species lacking yellow coloration and without attractive songs. Our models of price revealed high levels of phylogenetic correlation, and hence that closely related species tended to be sold for similar prices. We suggest that, on the basis of price, native species are more likely to be deliberately or accidentally released than alien species. Nevertheless, our survey of bird shops recorded 160 species alien to Taiwan (7,631 individuals), several of which are for sale cheaply and in large numbers. Alien bird species in trade therefore present an ongoing, non-trivial invasion risk on the island.     

Climate change increases risk of plant invasion in the Eastern United States

Invasive plant species threaten native ecosystems, natural resources, and managed lands worldwide. Climate change may increase risk from invasive plant species as favorable climate conditions allow invaders to expand into new ranges. Here, we use bioclimatic envelope modeling to assess current climatic habitat, or lands climatically suitable for invasion, for three of the most dominant and aggressive invasive plants in the southeast United States: kudzu (Pueraria lobata), privet (Ligustrum sinense; L. vulgare), and cogongrass (Imperata cylindrica). We define climatic habitat using both the Maxent and Mahalanobis distance methodologies, and we define the best climatic predictors based on variables that best ‘constrain’ species distributions and variables that ‘release’ the most land area if excluded. We then use an ensemble of 12 atmosphere-ocean general circulation models to project changes in climatic habitat for the three invasive species by 2100. The combined methodologies, predictors, and models produce a robust assessment of invasion risk inclusive of many of the approaches typically used individually to assess climate change impacts. Current invasion risk is widespread in southeastern states for all three species, although cogongrass invasion risk is more restricted to the Gulf Coast. Climate change is likely to enable all three species to greatly expand their ranges. Risk from privet and kudzu expands north into Ohio, Pennsylvania, New York, and New England states by 2100. Risk from cogongrass expands as far north as Kentucky and Virginia. Heightened surveillance and prompt eradication of small pockets of invasion in northern states should be a management priority.     

Establishment risk and potential invasiveness of the selected exotic amphibians from pet trade in the European Union

The pet trade has grown in recent years and become the most important pathway for the introduction of non-indigenous species of amphibians and reptiles worldwide. Amphibians traded on the pet market have been widely overlooked in systematic invasion studies, so their establishment potential and invasion dynamics remain poorly understood, despite the fact that the impact of invaders from this taxonomic group on native biota may be considerable. The determination of the most common species of amphibians traded as pets was based on a survey of the market in the Czech Republic, which is an export hub for ornamental aquatic animals into the European Union (EU). Subsequently, the establishment potential of the most common species for EU was determined using a proven risk assessment model. Amphibians that scored higher than the established species Xenopus laevis were additionally evaluated for their invasion potential using the Amphibian Invasiveness Screening Kit (AmphISK).Sixteen species of amphibians in pet market (14 Anura, 2Caudata) have an establishment potential in the EU. However, none of these species have reached the invasion potential score of already spreading species X. laevis and Lithobates catesbeianus. The species closest to the threshold value were Lithobates pipiens and Pelophylax saharicus. Amphibians represent a rather small group within all traded animals but this fact should not lead us to an underestimation of their potential invasiveness.     

Effect of Climate Change on Invasion Risk of Giant African Snail (Achatina fulica Férussac, 1821: Achatinidae) in India

The Giant African Snail (Achatina fulica) is considered to be one the world’s 100 worst invasive alien species. The snail has an impact on native biodiversity, and on agricultural and horticultural crops. In India, it is known to feed on more than fifty species of native plants and agricultural crops and also outcompetes the native snails. It was introduced into India in 1847 and since then it has spread all across the country. In this paper, we use ecological niche modeling (ENM) to assess the distribution pattern of Giant African Snail (GAS) under different climate change scenarios. The niche modeling results indicate that under the current climate scenario, Eastern India, peninsular India and the Andaman and Nicobar Islands are at high risk of invasion. The three different future climate scenarios show that there is no significant change in the geographical distribution of invasion prone areas. However, certain currently invaded areas will be more prone to invasion in the future. These regions include parts of Bihar, Southern Karnataka, parts of Gujarat and Assam. The Andaman and Nicobar and Lakshadweep Islands are highly vulnerable to invasion under changed climate. The Central Indian region is at low risk due to high temperature and low rainfall. An understanding of the invasion pattern can help in better management of this invasive species and also in formulating policies for its control.     

Analysis of the marine ornamental fish trade at Ceará State, northeast Brazil

Brazil is one of the leading exporters of ornamental fishes, mostly freshwater; however, monitoring of the trade is nearly non-existent in the country. This paper provides an initial assessment of a new venture, the marine aquarium fish trade at Ceará State, northeast Brazil, aiming to document the species traded, to provide preliminary estimates of numbers of specimens traded, and to identify priorities in data collection and monitoring. A total of 143 species and 199 304 fishes were traded. From the total, 109 species were native and represented 84% of the fishes traded. Thirty-four exotic species figured on the permits and amounted to nearly 16% of the exports; however, most of them consist of misidentified native species. Nearly 90% of the fish trade was directed to the international market. Official figures represent an underestimation of the total number of captured specimens.     

Ancestral origins and invasion pathways in a globally invasive bird correlate with climate and influences from bird trade

Invasive species present a major threat to global biodiversity. Understanding genetic patterns and evolutionary processes that reinforce successful establishment is paramount for elucidating mechanisms underlying biological invasions. Among birds, the ring‐necked parakeet (Psittacula krameri) is one of the most successful invasive species, established in over 35 countries. However, little is known about the evolutionary genetic origins of this species and what population genetic signatures tell us about patterns of invasion. We reveal the ancestral origins of populations across the invasive range and explore the potential influence of climate and propagule pressure from the pet trade on observed genetic patterns. Ring‐necked parakeet samples representing the ancestral native range (n = 96) were collected from museum specimens, and modern samples from the invasive range (n = 855) were gathered from across Europe, Mauritius and Seychelles, and sequenced for two mitochondrial DNA markers comprising 868 bp of cytochrome b and control region, and genotyped at 10 microsatellite loci. Invasive populations comprise birds that originate predominantly from Pakistan and northern areas of India. Haplotypes associated with more northerly distribution limits in the ancestral native range were more prevalent in invasive populations in Europe, and the predominance of Asian haplotypes in Europe is consistent with the higher number of Asian birds transported by the pet trade outside the native range. Successful establishment of invasive species is likely to be underpinned by a combination of environmental and anthropogenic influences.     

Molecular identification of the precise geographic origins of an invasive shrimp species in a globally significant Australian biodiversity hotspot

This report details the first detection of invasive freshwater shrimp in the south-west of Western Australia, a region recognised for its biodiversity and the vulnerability of its endemic species. The species was detected as part of biosecurity surveillance of Perth’s freshwater lakes. The introduced specimens were tentatively identified morphologically as Caridina indistincta, and then confirmed by molecular analysis as “species B” of that taxon, part of a species-complex native to eastern Australia. Phylogeographic analyses were then used to narrow down the likely source population to a small area of south-eastern Queensland, over 3500 kms across the continent from the invasion sites. The potential source area is heavily involved in the trade in freshwater species for aquaria and recreational fish stocking. This information will help in identifying the precise invasion vector and could thus allow more targeted management measures to prevent future imports of exotic aquatic invasive species.     

Will climate change favor exotic grasses over native ecosystem engineer species in the Amazon Basin?

Several anthropic disturbances, including deforestation, fires, the building of roads and dams, have intensified in Amazon in last decades. These disturbances contribute to an increase in the occurrence and intensity of extreme events, such as more frequent floods and more severe droughts, due to climate change. Along the Amazonian rivers, aquatic herbaceous plants, mainly of the Poaceae family, are very abundant and produce up to three times more biomass than the adjacent flooded forests, and some are considered ecosystem engineers given their structuring role in these environments. Invasive grasses have spread through the Neotropics and are gradually entering the Amazon via the Arc of Deforestation. These invasive species often attain high coverage, suppress other species, and become dominant in both disturbed and pristine habitats. The aim of this study was to establish the current and future distribution patterns of two native ecosystem engineer species (Echinochloa polystachya and Paspalum fasciculatum) and two invasive species (Urochloa brizantha and Urochloa decumbens) in the Amazon Basin. To predict the future climate, we used three scenarios, namely SSP1–2.6, SSP3–7.0 and SSP5–8.5 for the years 2040, 2080 and 2100, to project climatically suitable areas. The current climatically suitable range for the native ecosystem engineer species was estimated at 33–35% of the Amazon Basin, while the invasive ones have a range of 53–84% in potential climatically suitable areas. A decrease in the areas of suitability of the two ecosystem engineer species, E. polystachya and P. fasciculatum, was observed in all scenarios and years, while only the invasive U. brizantha showed an increase in suitable areas in all years. These results raise concerns about the invasion of grasses with high aggressive potential that could result in the exclusion of native ecosystem engineer species and their ecological roles.     

Potential geographic distribution of brown marmorated stink bug invasion (Halyomorpha halys)

Background

The Brown Marmorated Stink Bug (BMSB), Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), native to Asia, is becoming an invasive species with a rapidly expanding range in North America and Europe. In the US, it is a household pest and also caused unprecedented damage to agriculture crops. Exploring its climatic limits and estimating its potential geographic distribution can provide critical information for management strategies.

Methodology/Principals

We used direct climate comparisons to explore the climatic niche occupied by native and invasive populations of BMSB. Ecological niche modelings based on the native range were used to anticipate the potential distribution of BMSB worldwide. Conversely, niche models based on the introduced range were used to locate the original invasive propagates in Asia. Areas with high invasion potential were identified by two niche modeling algorithms (i.e., Maxent and GARP).

Conclusions/Significance

Reduced dimensionality of environmental space improves native model transferability in the invade area. Projecting models from invasive population back to native distributional areas offers valuable information on the potential source regions of the invasive populations. Our models anticipated successfully the current disjunct distribution of BMSB in the US. The original propagates are hypothesized to have come from northern Japan or western Korea. High climate suitable areas at risk of invasion include latitudes between 30°–50° including northern Europe, northeastern North America, southern Australia and the North Island of New Zealand. Angola in Africa and Uruguay in South America also showed high climate suitability.     

Pine invasions: climate predicts invasion success; something else predicts failure

Aim Explaining why some invasions fail while others succeed is a prevailing question in invasion biology. Different factors have been proposed to explain the success or failure of exotics. Evidence suggests that climate similarities may be crucial. We tested this using 12 species of the genus Pinus that have been widely planted and shown to be highly invasive. Pinus is among the best‐studied group of exotic species and one that has been widely introduced world‐wide, so we were able to obtain data on invasive and non‐invasive introductions (i.e. unsuccessful invasions; areas where after many decades of self‐sowing seeds there is no invasion). Location World‐wide. Methods We developed species distribution models for native ranges using a maximum entropy algorithm and projected them across the globe. We tested whether climate‐based models were able to predict both invasive and non‐invasive introductions. Results Appropriate climatic conditions seem to be required for these long‐lived species to invade because climates accurately predicted invasions. However, climate matching is necessary, but not sufficient to predict the fate of an introduction because most non‐invasive introductions were predicted to have triggered an invasion. Main conclusions Other factors, possibly including biotic components, may be the key to explaining why some introductions do not become invasions, because many areas where Pinus is not invading were predicted to be suitable for invasion based solely on climate.     

Modelling the impact of Hieracium spp. on protected areas in Australia under future climates

Anthropogenically-induced climate change is one of the most important global threats to biodiversity. Understanding its impact on the distribution of exotic plant species is critical for developing effective adaptation and management strategies. However, there is insufficient information currently available on the biodiversity at risk from 1) exotic plant invasions, 2) climate change, and 3) the interaction between these two major threats, to develop such strategies. We use ecological niche models as a first step to identify zones inside and outside Australian protected areas that may be most at risk from invasions of three species of Hieracium (hawkweeds) under current and future (2030 and 2070) climate scenarios, should current control and eradication methods fail. These perennial herbs are native to Europe and invasive to New Zealand and North America. Naturalised in Australia, hawkweeds threaten native tussock grasslands and the grazing industry, and have been placed on the National Alert List. Using eight ecological niche models currently available in the software package BIOMOD, we found that these species have yet to realize the extent of their climatic distribution under present day climate in Australia. As climate change accelerates, the climatic range of hawkweeds was projected to contract overall. However, much of the Australian Alps, which contain large contiguous tracts of reserves and many endemic species, will continue to retain climatically suitable areas for hawkweeds through to 2070. These results emphasise the need for ongoing monitoring as well as focused control to minimize the likelihood of hawkweeds realizing their invasive potential in protected areas and beyond.