Introduction Of Invasive Species Research Articles

Ecological impact of a generalist invader in the aquatic food web is mediated by environmental context

Abstract Freshwater ecosystems are threatened by the introduction of invasive species. Generalist invaders often compete with native species for shared resources, resulting in possible native species niche displacement. However, environmental heterogeneity may modulate the level of individual specialisation in invasive species, altering the outcome of interspecific competition between invasive and native species. The objectives of our study were to (1) evaluate the environmental context of dietary specialisation and trophic position of an invasive species according to the Environmental Matching Hypothesis (EMH), and (2) consider how the environmental context of invasive species dietary resource use may influence the dietary niche of native species competing for similar resources. Resource use, trophic position and dietary niche were determined using gut content and stable isotope analyses for the invasive round goby (Negobius melanostomus) and the native yellow perch (Perca flavescens), along environmental gradients in an invaded fluvial ecosystem. Our results were in support of EMH for the invader diet and resource specialisation, but not trophic position. Under environmental conditions of high water‐conductivity, round gobies were generalists feeding mostly on pelagic prey. Under more challenging environmental conditions of low water‐conductivity, the invader specialised on preferred high‐quality benthic prey. The ecological impact of the round goby was greatest at low water‐conductivity sites where the invader was a benthic specialist; there was a greater relative dietary niche overlap between the invader and the native species. Our study uniquely illustrates how invasive species’ resource specialisation can be modulated by spatial environmental heterogeneity within ecosystems, and how this can subsequently alter the ecological impact of the invader on native species in aquatic food webs.

Riparian woody plant communities in the Romanian Carpathians: Species diversity and community structure of Salix and Hippophaë communities.

Riparian woody plant communities, including shrubs and trees, are essential for maintaining biodiversity, protecting against floods, reducing erosion, and transporting nutrients. However, these habitats are greatly threatened by human activities, particularly agricultural land acquisition, and the introduction of invasive species. This study examined species diversity and interspecific association in riparian woody plant communities along rivers in the Romanian Carpathians. The study focused on communities of Salix purpurea, S. alba, and Hippophaë rhamnoides in mountain regions, with varying sampling efforts at different sites for each species. A total of 174 plant species were found, predominantly herbaceous (77.9%), followed by trees (11.6%) and shrubs (10.5%). While S. alba and S. purpurea communities show high species richness and abundance, S. alba has slightly higher diversity (H' ≈ 2.23, SD = 0.28) than S. purpurea (H' ≈ 1.69, SD = 0.42). Contrarily, significant differences exist between H. rhamnoides and S. alba communities in species richness (p = .007) and Shannon diversity (p = .004). PCA analysis elaborated on distinct distribution patterns of plant associations within habitats S. purpurea community, H. rhamnoides community, and S. alba community. Four invasive species (Oenothera biennis L. and Oxalis stricta L. in S. alba communities, Reynoutria sachalinensis Nakai in both S. purpurea and H. rhamnoides communities, and Erigeron canadensis L. in H. rhamnoides communities) were identified, as requiring conservation efforts. Hemicryptophytes dominate species richness, while microphanerophytes and megaphanerophytes significantly contribute to plant abundance. H. rhamnoides formed Hippophaë rhamnoides dunes (2160) Natura 2000 habitat, while S. alba created galleries within the 92A0 Salix alba and Populus alba habitat. In conclusion, the findings from this study highlight the importance of preserving riparian habitats because their value goes beyond local or regional considerations and extends to the global scale due to their unique characteristics.

Exploring the knowledge and application of biosecurity practices related to invasive alien species in field research in Croatia

Accidental introductions of invasive alien species (IAS) are increasingly prevalent and costly. Anthropogenic activities, including fieldwork activities of researchers, pose a risk for the unintentional spread of IAS. However, specific biosecurity policies and measures to prevent accidental introductions and the secondary spread of IAS are lacking in many European countries, primarily relying on researchers’ awareness of the issue. This study aimed to evaluate the biosecurity practices of researchers in Croatia during their fieldwork activities through an anonymous online survey distributed to over 63 institutions. The survey was completed by 172 respondents from 45 institutions and aimed to assess their knowledge of IAS and awareness of biosecurity risks they can pose. The results showed that even though more than half of the participants worked in the field of biology and had at least some knowledge of IAS, the majority used only the most basic and least efficient cleaning approaches for fieldwork equipment, clothes, and footwear, which are not sufficient for preventing unintentional IAS introductions. Moreover, vehicle cleaning was the most neglected biosecurity measure in our study, with up to 60% of respondents never performing it and only 12% always performing at least some type of vehicle cleaning. Respondents with the best knowledge of IAS posed a significant risk during their fieldwork activities but at the same time demonstrated the best understanding of biosecurity measures and had the best biosecurity performance. Furthermore, students were identified as a high-risk group since they visited the highest number of locations during fieldwork and used the equipment most often but cleaned it the least frequently. Based on obtained results, we discuss potential interventions that could help manage accidental IAS introductions at the national and EU levels.

Expansion of fluvial transport of commodities through the Pantanal floodplains of Brazil: Potential impacts and interference by climate change

AbstractInland waterways have historically been viewed as a desirable means for transporting commodities. However, creating and maintaining navigable river channels can entail substantial geomorphological modifications, resulting in changes to the ecohydrology of a river and its adjacent floodplains. In addition, barge traffic has important environmental impacts. The proposed expansion of the Paraguay River Hidrovia through the Pantanal floodplains of Brazil will negatively impact biodiversity due to bank erosion, water pollution, and the introduction of invasive species. Dredging would decrease the area and duration of inundation of connected floodplains renowned for their biodiversity, including fish and wildlife. Furthermore, the effects of the Hidrovia on greenhouse gas emissions are potentially important, although the net effects are complex and require further research. Global climate change is projected to cause greater variability in rainfall and river levels, with longer and more severe low water periods that would impede navigability and require further channel modifications. Modifications of the Paraguay River channel that lower the water levels and reduce the extent of surface water persisting during the dry season would negatively impact aquatic life in the main channel as well as in the floodplains, where recent increases in wildfire severity and excessive heat are already stressors. These changes threaten traditional livelihoods for people in the Pantanal, including artisanal fisheries, cattle ranching, and ecotourism.

A Fuzzy Ballast Water Risk Assessment Model in Maritime Transport

Recent years have witnessed a growing awareness of the critical role that maritime transport plays in global sustainability, given its significant environmental, economic, and social impacts. Central to this concern is the management of ballast water, which, if not properly treated, can lead to the introduction of invasive species, biodiversity loss, and substantial economic and health repercussions. Traditional risk assessment models often fail to capture the complex uncertainties inherent in environmental risks associated with ballast water. This study introduces an innovative fuzzy logic-based risk assessment model designed to enhance decision-making processes in maritime operations by accurately assessing and mitigating the environmental risks of ballast water discharge. The model, structured using three fuzzy systems, integrates human reasoning with mathematical precision, providing an effective tool for sustainable maritime practices. The integrated fuzzy system employs 18 variables as inputs and yields three outputs (ballasting, ballast exchange, and de-ballasting risk). To evaluate the performance of the developed system, various data sets are used and tested through the MATLAB Fuzzy Toolbox. By aligning maritime operations with sustainability principles, this research contributes to the preservation of marine ecosystems, supports the economic stability of marine-dependent industries, and safeguards public health, underscoring the interconnectivity of maritime transport management with overarching sustainability objectives.

Length-Weight Relationship and Condition Factor of Introduced Red Devil Cichlid Amphilophus labiatus, in Lake Sentani, Indonesia

Papua’s freshwater ecosystems in the western part of New Guinea have begun to record widespread introductions of invasive species over the past decade. This lake's most dominant and common exotic species is Amphilophus labiatus (Günther, 1864). A study was conducted to document the length-weight relationship and condition factor of these fish in Lake Sentani. From June to August 2019, fish were caught using floating gillnets at six locations around the lake. Total length (TL) (mm), body depth (mm), and body weight (grams) were measured, and condition factor based on gender, body weight, and body length were observed in 345 fish, including 264 males and 81 males. The growth pattern of A. labiatus is positively allometric, with b values ranging from 3.19 to 3. 20 and coefficients of determination (r2) ranging from 0.84 to 0.87. Although the average body length of A. labiatus males was shorter than females, condition factor (CF) values were not significantly different between the sexes and ranged from 0. 64 to 2.03 (0.97 ± 1.17, mean ± SD). For males, it went from 0.67 to 1.19 (0.94 ± 0.13 mean ± SD). However, monthly CF data show a significant decrease in CF in August, suggesting that spawning events occur in late July or early August. A. labiatus grows well and colonizes habitats throughout Lake Sentani.

Climate change will likely facilitate invasion of Asian orchid Eulophia graminea into new areas

Climate change plays an increasing role in the global biodiversity crisis. Alteration in local climatic conditions not only can negatively affect native biodiversity but also can accelerate the introduction and spread of invasive species. In this study the ecological niche modelling approach was used to evaluate possible changes in the distribution of suitable niches of invasive orchid Eulophia graminea within its native (Asia) and non-native geographical range (America, Australia). We mapped the current potential range of this species and analysed three various projections of future climate (for 2100) each with four different climate change scenarios (SSPs). Calculated niche overlap indexes indicated low similarity of niches occupied by native and invasive populations of E. graminea and Australian populations seem to be the most unique, while American and Asian groups share partially similar niches. The occurrence of the American population of E. graminea was correlated especially with the temperature seasonality, while the Asian and Australian populations with annual precipitation and precipitation of the wettest quarter. As indicated in our analyses within Asia and America, E. graminea does not occupy all climatically suitable niches. On the other hand, in Australia the species studied already occupies all appropriate niche space. Climate change will likely be favorable for species studied to expand its range if the biotic components of its niche space (e.g., mycorrhizal fungi) will respond similarly. The most significant range expansion is predicted to occur in Australia which is interesting considering the marginally suitable habitats that E. graminea currently occupies.

Status of floristic diversity and impact of development on two sacred groves from Maval Tehsil (Maharashtra, India) after a century

Global urbanisation and anthropogenic activities are leading to a decline in religious beliefs and adversely affecting the biodiversity, ecology, and environmental sustainability of sacred groves, particularly in Lonavala (Rye Wood Park) and Karla Grove in Maval Tehsil, Pune district, Maharashtra, India. The Lonavala Grove, situated at 18.749° N, 73.403° E, and 622 m, and the Karla Grove, located at 18.760° N, 73.478° E, with an elevation of 621 m, both within the Western Ghats, are undergoing transformations due to landscape gardens and urban developments despite their historical significance. Gammie Alexander‘s 1903 floristic research identified 84 species across both groves, but our present study reveals a significant decline. Lonavala and Karla groves now host 46 genera and 42 species and 25 genera and 29 species, respectively, totaling 120 species from 49 families and 110 genera. This decline is attributed to the introduction of alien and invasive species, resulting in the disappearance of six indigenous species over the past century. The research aims to explore and document changes in floristic diversity, utilising remote sensing methods like NDVI for growth and deterioration assessment, measuring tree and liana girth, and analysing the impact on native flora due to the spread of alien species.

Current Status of La Crosse Virus in North America and Potential for Future Spread.

La Crosse virus (LACV) is an arthropod-borne RNA virus with substantial potential for future spread in North America. La Crosse virus is responsible for La Crosse encephalitis, a leading cause of arboviral encephalitis in children in the United States. Primarily transmitted by Aedes triseriatus (Eastern treehole) mosquitos and amplified by small mammal hosts, LACV has caused infections throughout the upper Midwest and, more recently, the mid-Atlantic and southeastern United States. Notably, in recent years, infections have also been identified increasingly in the Appalachian region. Anthropogenic and environmental factors have likely contributed to recent LACV spread, including the introduction of invasive vector species (especially Ae. albopictus), biotic interactions between and among vector and host species, land-use change, habitat disturbance, increased human travel and transport, and rising global temperatures. Prevention and control strategies, such as increased surveillance of vector and host populations, increased awareness among populations at risk for infection, and increased awareness among physicians are needed to limit future spread. Continued climate change with increases in global temperatures and erratic weather patterns may result in the expansion of competent mosquito vector species and thus could facilitate the geographic spread of LACV.

How to deal with invasive species that have high economic value?

The ever-accelerating process of introduction and establishment of invasive alien species (IAS) in marine waters requires engaging different actors in the management and planning. To address this challenge, stakeholders need an integrated approach for defining actions of control and management within an ecosystem-based framework: to seek and enhance coordination, collaboration and trust among all stakeholders affected by changes in linked marine social - ecological systems. This study explores the complexities and opportunities in managing economically valuable IAS, demonstrating the need for tailored management strategies that consider key ecological details needed for successful control such as timing of removals and key economic considerations such as appropriate incentive mechanisms and time horizons in favor of long-term conservation goals. We propose a set of actions that can serve as a roadmap for effective IAS control and management, considering their dual role as nuisances and valuable resources. These actions pertain to local, regional and international levels, encouraging meaningful stakeholder engagement through co-management structures that can foster the development of robust management plans, enabling better IAS control. The outcome holds potential for positive contributions to the blue economy— sustainable use of marine resources, including fisheries, tourism, and renewable energy— and for meeting sustainability objectives.

Multiple records of the introduced parthenogenetic Smooth-scaled Tegulet, <i>Gymnophthalmus underwoodi</i> Grant 1958, in Puerto Rico

The introduction of invasive species to islands can be devastating to local biota. While many invasive species’successful colonization of new habitats can be attributed to features like high fecundity or low mate selectivity,parthenogenetic species pose a unique threat in their ability to reproduce asexually at high rates. The Smooth-scaledTegulet (Gymnophthalmus underwoodi), first described from Barbados in the 1950s, has since been documented as anintroduced species across additional Lesser and Greater Antillean islands as well as northwestern Brazil and Venezuela.Herein we report multiple individuals from Puerto Rico, including the first genetic records, which indicate that theindividuals on this island are most closely related to populations recorded from Brazil and Montserrat. Additionalgenetic information is necessary to determine the timing and migration of this species across the Caribbean. Regardless,the continued geographic expansion of this parthenogen across the Caribbean could present a threat to local fauna.

Live‐bait industry as a pathway for movement of nonnative and invasive species: Implications for conservation of native Texas fishes

AbstractObjectiveLive‐bait species are widely used in recreational fishing throughout the United States. However, the use of invasive fish species as live bait has been identified as a common pathway for their introduction into aquatic ecosystems. We assessed the role that the live‐bait industry has in facilitating the introduction of nonnative and invasive species into Texas rivers. We focused on two invasive cyprinodontid species, the Sheepshead Minnow Cyprinodon variegatus and Gulf Killifish Fundulus grandis, which are believed to have been introduced into inland Texas rivers via bait‐bucket releases by anglers.MethodsWe conducted telephone and in‐person surveys of live‐bait shops in Texas on a seasonal basis (summer, fall, winter, spring) for 1 year. Locally owned bait shops and regional aquaculture facilities and hatcheries were included in the surveys.ResultSurveys did not reveal the presence of these invasive cyprinodontids in inland bait shops but did reveal the sale of nonnative Goldfish Carassius auratus and their black color morph, the black salty goldfish. Surveys conducted among inland and coastal live bait shops confirmed the sale of only one nonnative bait fish and six bait items native only to certain regions of Texas. Telephone surveys with aquaculture industry experts revealed that the aquaculture industry was also facilitating the movement of nonnative game and nongame fish species throughout the state.ConclusionGiven the potential for nonnative and invasive species to negatively affect recipient aquatic ecosystems, the continued distribution of such species within the aquaculture industry represents a potential threat in Texas. Our findings highlight the need for close monitoring of the live‐bait industry in the state to prevent further introductions into inland waters and reduce potential ecological risks to native fish populations and overall ecosystem functions and services.

Ensemble evaluation of potential distribution of Procambarus clarkii using multiple species distribution models.

Procambarus clarkii is a notorious invasive species that has led to ecological concerns owing to its high viability and rapid reproduction. South Korea, a country exposed to a high risk of introduction of invasive species due to active international trade, has suffered from recent massive invasions by invasive species, necessitating the evaluation of potential areas requiring intensive monitoring. In this study, we developed two different types of species distribution models, CLIMEX and random forest, for P. clarkii using occurrence records from the United States. The potential distribution in the United States was predicted along coastal lines and inland regions located below 40°N latitude The model was then applied to evaluate the potential distribution in South Korea, and an ensemble map was constructed to identify the most vulnerable domestic regions. According to both models, the domestic potential distribution was highest in most areas located at low altitudes. In the ensemble model, most of the low-altitude western regions, the eastern coast, and some southern inland regions were predicted to be suitable for the distribution of P. clarkii, and a similar distribution pattern was predicted when the model was projected into the future climate. Through this study, it is possible to secure basic data that can be used for the early monitoring of the introduction and subsequent distribution of P. clarkii.

A novel deep learning‐based bioacoustic approach for identification of look‐alike white‐eye (Zosterops) species traded in wildlife markets

The songbird trade crisis in East and South East Asia has been fuelled by high demand, driving many species to the brink of extinction. This demand, driven by the desire for songbirds as pets, for singing competitions and for prayer animal release has led to the overexploitation of numerous species and the introduction and spread of invasive alien species and diseases to novel environments. The ability to identify traded species efficiently and accurately is crucial for monitoring bird trade markets, protecting threatened species and enforcing wildlife laws. Citizen scientists can make major contributions to these conservation efforts but may be constrained by difficulties in distinguishing ‘look‐alike’ bird species traded in markets. To address this challenge, we developed a novel deep learning‐based Artificial Intelligence (AI) bioacoustic tool to enable citizen scientists to identify bird species traded in markets. To this end, we used three major avian vocalization databases to access bioacoustic data for 15 morphologically similar White‐eye (Zosterops) species that are commonly traded in Asian wildlife markets. Specifically, we employed the Inception v3 pre‐trained model to classify the 15 White‐eye species and ambient sound (i.e. non‐bird sound) using 448 bird recordings we obtained. We converted recordings into spectrogram (i.e. image form) and used eight image augmentation methods to enhance the performance of the AI neural network through training and validation. We found that recall, precision and F1 score increased as the amount of data augmentation increased, resulting in up to 91.6% overall accuracy and an F1 score of 88.8% for identifying focal species. Through the application of bioacoustics and deep learning, this approach would enable citizen scientists and law enforcement officials efficiently and accurately to identify prohibited trade in threatened species, making important contributions to conservation.

Molecular identification of cattle ticks in the Greater Accra Region of Ghana: a high occurrence of Rhipicephalus microplus.

Ticks are competent vectors of a wide range of pathogens. They are of veterinary and public health importance as they affect both animal and human health. Transhumance and the transboundary movements of cattle within the West African Sub-region have facilitated the spread of ticks which threatens the introduction of invasive species. Currently, Rhipicephalus microplus have been identified in the Upper East Region of Ghana which could mean a wider distribution of the species across the country due to livestock trade. This study focused on three sites in the Greater Accra Region, which serves as the gateway to receiving most of the cattle transported from the northern regions of Ghana. Ticks were sampled from August 2022 in the wet season to January 2023 in the dry season. Three tick genera were identified: Amblyomma (19.5%), Hyalomma (1.1%), and Rhipicephalus (79.3%) from the 1,489 feeding ticks collected from cattle. Furthermore, Rhipicephalus microplus, Hyalomma rufipes and Amblyomma variegatum were identified molecularly using primers that target the mitochondrial COI gene. There was a significant association between the tick species and seasons (p < 0.001). Finding R. microplus in this study indicates the extent of the spread of this invasive tick species in Ghana and highlights the need for efficient surveillance systems and control measures within the country.

Avian Plasmodium in invasive and native mosquitoes from southern Spain

BackgroundThe emergence of diseases of public health concern is enhanced by factors associated with global change, such as the introduction of invasive species. The Asian tiger mosquito (Aedes albopictus), considered a competent vector of different viruses and parasites, has been successfully introduced into Europe in recent decades. Molecular screening of parasites in mosquitoes (i.e. molecular xenomonitoring) is essential to understand the potential role of different native and invasive mosquito species in the local circulation of vector-borne parasites affecting both humans and wildlife.MethodsThe presence of avian Plasmodium parasites was molecularly tested in mosquitoes trapped in five localities with different environmental characteristics in southern Spain from May to November 2022. The species analyzed included the native Culex pipiens and Culiseta longiareolata and the invasive Ae. albopictus.ResultsAvian Plasmodium DNA was only found in Cx. pipiens with 31 positive out of 165 mosquito pools tested. None of the Ae. albopictus or Cs. longiareolata pools were positive for avian malaria parasites. Overall, eight Plasmodium lineages were identified, including a new lineage described here. No significant differences in parasite prevalence were found between localities or sampling sessions.ConclusionsUnlike the invasive Ae. albopictus, Cx. pipiens plays a key role in the transmission of avian Plasmodium in southern Spain. However, due to the recent establishment of Ae. albopictus in the area, further research on the role of this species in the local transmission of vector-borne pathogens with different reservoirs is required.Graphical

Economic costs of invasive non-native species in urban areas: An underexplored financial drain

Urbanization is an important driver of global change associated with a set of environmental modifications that affect the introduction and distribution of invasive non-native species (species with populations transported by humans beyond their natural biogeographic range that established and are spreading in their introduced range; hereafter, invasive species). These species are recognized as a cause of large ecological and economic losses. Nevertheless, the economic impacts of these species in urban areas are still poorly understood. Here we present a synthesis of the reported economic costs of invasive species in urban areas using the global InvaCost database, and demonstrate that costs are likely underestimated. Sixty-one invasive species have been reported to cause a cumulative cost of US$ 326.7 billion in urban areas between 1965 and 2021 globally (average annual cost of US$ 5.7 billion). Class Insecta was responsible for >99 % of reported costs (US$ 324.4 billion), followed by Aves (US$ 1.4 billion), and Magnoliopsida (US$ 494 million). The reported costs were highly uneven with the sum of the five costliest species representing 80 % of reported costs. Most reported costs were a result of damage (77.3 %), principally impacting public and social welfare (77.9 %) and authorities-stakeholders (20.7 %), and were almost entirely in terrestrial environments (99.9 %). We found costs reported for 24 countries. Yet, there are 73 additional countries with no reported costs, but with occurrences of invasive species that have reported costs in other countries. Although covering a relatively small area of the Earth's surface, urban areas represent about 15 % of the total reported costs attributed to invasive species. These results highlight the conservative nature of the estimates and impacts, revealing important biases present in the evaluation and publication of reported data on costs. We emphasize the urgent need for more focused assessments of invasive species' economic impacts in urban areas.

First inventory of Ants (Hymenoptera: Formicidae) with detection of potential invasive species in National Park of Ehotilés islands, Côte d’Ivoire

Estuarine and wetland ecosystems are becoming increasingly altered by the concentration of human population near the coastline. A major threat to biodiversity related to this human footprint is the introduction of invasive alien species, particularly in isolated ecosystems like islands where biological invasion is often harmful. The National Park of Ehotilés Islands is an archipelago of 6 islands and a RAMSAR site subjected to disturbances activities like agriculture, illegal fisheries, and tourism. These factors often act as an accelerator for the introduction of invasive species. However, there is a lack of research conducted on insects, specifically ants on these islands. This study aimed to inventory the present ant fauna and estimate the vulnerability to tramp and potential invasive ant species. Ants were collected using Winkler, pitfall, and funnel traps on five islands. In total, 76 ant species were recorded. These species are distributed into 20 genera and five subfamilies: Dolichoderinae (5 species), Formicinae (11 species), Myrmicinae (49 species), Ponerinae (11 species) and Proceratiinae (1 species). We also detected two tramp and potentially invasive species: the ghost ant Tapinoma melanocephalum and the big-headed ant Pheidole megacephala. Ant communities are dominated by six species, namely Odontomachus troglodytes, Oecophylla longinoda, Nylanderia lepida, Pheidole sp.2, Monomorium invidium, and the invasive ghost ant Tapinoma melanocephalum. This work is the first to inventory ants on the Islands of Ehotilés National Park and may serve as a basis for conservation decisions as it demonstrates that this park is not spared from the introduction of invasive ant species.

A simulation study evaluating how population survival and genetic diversity in a newly established population can be affected by propagule size, extinction rates, and initial heterozygosity.

The introduction and establishment of invasive species in regions outside their native range, is one of the major threats for the conservation of ecosystems, affecting native organisms and the habitat where they live in, causing substantial biological and monetary losses worldwide. Due to the impact of invasive species, it is important to understand what makes some species more invasive than others. Here, by simulating populations using a forward-in-time approach combining ecological and single polymorphic nucleotides (SNPs) we evaluated the relation between propagule size (number of individuals = 2, 10, 100, and 1,000), extinction rate (with values 2%, 5%, 10%, and 20%), and initial heterozygosity (0.1, 0.3, and 0.5) on the population survival and maintenance of the heterozygosity of a simulated invasive crab species over 30 generations assuming a single introduction. Our results revealed that simulated invasive populations with initial propagule sizes of 2-1,000 individuals experiencing a high extinction rate (10-20% per generation) were able to maintain over 50% of their initial heterozygosity during the first generations and that under scenarios with lower extinction rates invasive populations with initial propagule sizes of 10-1,000 individuals can survive up to 30 generations and maintain 60-100% of their initial heterozygosity. Our results can help other researchers better understand, how species with small propagule sizes and low heterozygosities can become successful invaders.

An Influx of Non-Native Bird Species into the Natural Environment Owing to the Accidental Release of Pet Birds in Japan.

The escape of pet birds into the wild raises concerns about the introduction of invasive avian species. This study investigated the impact of escaped pet birds on the introduction of non-native species in Japan. Data sourced from four lost-and-found pet websites between January 2018 and December 2021 revealed 12,125 recorded escapes exhibiting both daily occurrences and seasonal fluctuations. Statistical modeling identified the monthly average temperature (positively correlated) and maximum electricity demand (negatively correlated) as influential factors. Text analysis revealed "window" and "open" as frequently cited reasons for escapes. Budgerigars (Melopsittacus undulatus) and Cockatiels (Nymphicus hollandicus) accounted for 76% of the total escape, suggesting a low perceived risk of establishment in nonnative environments. Interestingly, two globally established invasive species, the Rose-ringed Parakeet (Psittacula krameri) and Monk Parakeet (Myiopsitta monachus), were among the escaped birds. While the Rose-ringed Parakeet is locally naturalized in Tokyo and its adjacent prefectures, the Monk Parakeet failed to establish itself in Japan. Despite the limited number of escaped Monk Parakeets, ongoing efforts are crucial for preventing the potential re-establishment of species with such capabilities.