Deliberate Introductions Research Articles

Ancient and Recent Hybridization in the Oreochromis Cichlid Fishes.

Cichlid fishes of the genus Oreochromis (tilapia) are among the most important fish for inland capture fisheries and global aquaculture. Deliberate introductions of non-native species for fisheries improvement and accidental escapees from farms have resulted in admixture with indigenous species. Such hybridization may be detrimental to native biodiversity, potentially leading to genomic homogenization of populations and the loss of important genetic material associated with local adaptation. By contrast, introgression may fuel diversification when combined with ecological opportunity, by supplying novel genetic combinations. To date, the role of introgression in the evolutionary history of tilapia has not been explored. Here we studied both ancient and recent hybridization in tilapia, using whole genome resequencing of 575 individuals from 23 species. We focused on Tanzania, a natural hotspot of tilapia diversity, and a country where hybridization between exotic and native species in the natural environment has been previously reported. We reconstruct the first genome-scale phylogeny of the genus and reveal prevalent ancient gene flow across the Oreochromis phylogeny. This has likely resulted in the hybrid speciation of one species, O. chungruruensis. We identify multiple cases of recent hybridization between native and introduced species in the wild, linked to the use of non-native species in both capture fisheries improvement and aquaculture. This has potential implications for both conservation of wild populations and the development of the global tilapia aquaculture industry.

Biological control of weeds in Aotearoa / New Zealand: History, science and achievements to date

Aotearoa / New Zealand is the leading country globally in the use of biological control agents to combat introduced pest weed species. Here we review the history of biological control in Aotearoa / New Zealand, compile a list of current, self-introduced and accidentally introduced biocontrol agents, and list the agents currently under consideration for introduction to Aotearoa / New Zealand (accurate to 2021). We discuss the science and procedures in place for the safe introduction of a new biocontrol agent and discuss the public’s perception of biological control within Aotearoa / New Zealand. Since the 1920s there have been 79 control agents released; 68 of those species were deliberate introductions, eight self-introductions and three accidental introductions. Additionally, there have been eight reported occurrences of non-target-species attack by biological control agents in Aotearoa / New Zealand, all of which cause minor damage to their unintended hosts. Prior to their introduction to Aotearoa / New Zealand, potential biological control agents are required to undergo rigorous research and host-specificity testing to ensure that the agent does not pose a risk to indigenous taxa through non-target attack. This research is essential, as it ensures a precautionary approach is taken prior to introductions, which, in turn, provides the wider public with confidence in the validity of biocontrol agents as a means to manage weed species in Aotearoa / New Zealand.

Does non‐native diversity mirror Earth's biodiversity?

AbstractAimHuman activities have introduced numerous non‐native species (NNS) worldwide. Understanding and predicting large‐scale NNS establishment patterns remain fundamental scientific challenges. Here, we evaluate if NNS composition represents a proportional subset of the total species pool available to invade (i.e. total global biodiversity), or, conversely, certain taxa are disproportionately pre‐disposed to establish in non‐native areas.LocationGlobal.Time periodPresent day.Major taxa studiedGlobal diversity.MethodsWe compiled one of the most comprehensive global databases of NNS (36,822 established species) to determine if NNS diversity is a representative proportional subset of global biodiversity.ResultsOur study revealed that, while NNS diversity mirrors global biodiversity to a certain extent, due to significant deviance from the null model it is not always a representative proportional subset of global biodiversity. The strength of global biodiversity as a predictor depended on the taxonomic scale, with successive lower taxonomic levels less predictive than the one above it. Consequently, on average, 58%, 42% and 28% of variability in NNS numbers were explained by global biodiversity for phylum, class and family respectively. Moreover, global biodiversity was a similarly strong explanatory variable for NNS diversity among regions, but not habitats (i.e. terrestrial, freshwater and marine), where it better predicted NNS diversity for terrestrial than for freshwater and marine habitats. Freshwater and marine habitats were also greatly understudied relative to invasions in the terrestrial habitats. Over‐represented NNS relative to global biodiversity tended to be those intentionally introduced and/or ‘hitchhikers’ associated with deliberate introductions. Finally, randomness is likely an important factor in the establishment success of NNS.Main conclusionsBesides global biodiversity, other important explanatory variables for large‐scale patterns of NNS diversity likely include propagule and colonization pressures, environmental similarity between native and non‐native regions, biased selection of intentionally introduced species and disparate research efforts of habitats and taxa.

Temporal collections to study invasion biology.

Biological invasions represent an extraordinary opportunity to study evolution. This is because accidental or deliberate species introductions have taken place for centuries across large geographical scales, frequently prompting rapid evolutionary transitions in invasive populations. Until recently, however, the utility of invasions as evolutionary experiments has been hampered by limited information on the makeup of populations that were part of earlier invasion stages. Now, developments in ancient and historical DNA technologies, as well as the quickening pace of digitization for millions of specimens that are housed in herbaria and museums globally, promise to help overcome this obstacle. In this review, we first introduce the types of temporal data that can be used to study invasions, highlighting the timescale captured by each approach and their respective limitations. We then discuss how ancient and historical specimens as well as data available from prior invasion studies can be used to answer questions on mechanisms of (mal)adaptation, rates of evolution, or community-level changes during invasions. By bridging the gap between contemporary and historical invasive populations, temporal data can help us connect pattern to process in invasion science. These data will become increasingly important if invasions are to achieve their full potential as experiments of evolution in nature.

Analysing ecological dynamics with relational event models: The case of biological invasions

AbstractAimsSpatio‐temporal processes play a key role in ecology, from genes to large‐scale macroecological and biogeographical processes. Existing methods studying such spatio‐temporally structured data either simplify the dynamic structure or the complex interactions of ecological drivers. The aim of this paper is to present a generic method for ecological research that allows analysing spatio‐temporal patterns of biological processes at large spatial scales by including the time‐varying variables that drive these dynamics.LocationGlobal analysis at the level of 272 regions.MethodsWe introduce a method called relational event modelling (REM). REM relies on temporal interaction dynamics that encode sequences of relational events connecting a sender node to a recipient node at a specific point in time. We apply REM to the spread of alien species around the globe between 1880 and 2005, following accidental or deliberate introductions into geographical regions outside of their native range. In this context, a relational event represents the new occurrence of an alien species given its former distribution.ResultsThe application of relational event models to the first reported invasions of 4835 established alien species outside of their native ranges from four major taxonomic groups enables us to unravel the main drivers of the dynamics of the spread of invasive alien species. Combining the alien species first records data with other spatio‐temporal information enables us to discover which factors have been responsible for the spread of species across the globe. Besides the usual drivers of species invasions, such as trade, land use and climatic conditions, we also find evidence for species‐interconnectedness in alien species spread.ConclusionsRelational event models offer the capacity to account for the temporal sequences of ecological events such as biological invasions and to investigate how relationships between these events and potential drivers change over time.

The Importance of Thermally Abnormal Waters for Bioinvasions—A Case Study of Pistia stratiotes

Thermally abnormal waters represent safe sites for alien invasive plants requiring warmer conditions than provided by the ambient temperatures in the temperate zone. Therefore, such safe sites are frequently inhabited by tropical and sub-tropical plants. By performing a literature review we assessed that at least 55 alien aquatic plant taxa from 21 families were found in thermally abnormal waters in Europe. The majority of these taxa are submerged or rooted macrophytes. Six taxa are listed as quarantine pests according to EPPO. Among these, Pistia stratiotes is present in seven European countries, most of the records of this presence being recent. We studied P. stratiotes in a thermally abnormal stream where a persistent population was able to survive harsh winters. Models showed that the optimum temperature for P. stratiotes biomass was 28.8 ± 3.5 °C. Here, we show that air temperatures had a higher influence on the photosynthetic efficiency of P. stratiotes, estimated by chlorophyll fluorescence measurements, than did water temperatures. Generally, growth, and consequently surface cover for free-floating plants, cannot be explained solely by thermally abnormal water temperatures. We conclude that even though the majority of thermophile alien plant occurrences resulted from deliberate introductions, thermally abnormal waters pose an invasion risk for further deliberate, accidental, or spontaneous spread, which might be more likely for free-floating macrophytes.

Unravelling another mystery: Parasite escape and host‐switching vary spatially in non‐indigenous populations of Japanese mystery snails

Abstract Due to anthropogenic mechanisms, global freshwater biodiversity is declining, and non‐indigenous species are consistently cited as a major threat to native ecosystems. In particular, exotic freshwater gastropods and their parasites have invaded ecosystems through deliberate introductions and/or accidental transfer. In many cases, introduced hosts experience parasite escape in their non‐indigenous range by leaving behind some of their native parasite load during introduction. We investigated whether the Japanese mystery snail, Heterogen japonica, may be exhibiting signatures of parasite escape in non‐indigenous populations in the mid‐Atlantic U.S.A. by comparing the prevalence and diversity of trematode parasites in H. japonica and co‐occurring indigenous snails. Because trematodes can severely impact snail host reproduction, they are an important parasite group to investigate using comparative parasite analyses. Finally, we used genetic data to elucidate whether host switching of trematode lineages had occurred among the indigenous and non‐indigenous snails. Six locations from Richmond, Virginia to Washington, D.C. were surveyed for non‐indigenous and indigenous snails in 2018 and 2019. A random subset of each species was measured, dissected, sexed, and examined for parasite diversity. Brooding embryos were also counted in non‐indigenous snails. Among all snails, native species had a higher diversity of trematode (digenean and aspidogastrean) parasites than the invasive mystery snail, and infection was also influenced by site. Although H. japonica was uninfected at the majority of sites, it had moderate prevalence (up to 34%) of aspidogastrean trematodes at two sites. Female H. japonica infected with aspidogastreans had significantly fewer brooding embryos than uninfected snails. We found additional associates such as ciliates, nematodes, and the oligochaete Chaetogaster sp. in indigenous snails; of these, only ciliates and nematodes were found in association with H. japonica at comparatively low prevalence. While H. japonica has escaped several trematode species, specific populations still had high prevalence of aspidogastreans, the highest of which was found where H. japonica co‐occurred with the indigenous snail Elimia virginica. Genetic data found at least two cryptic lineages of aspidogastreans, and one was shared between H. japonica and E. virginica, suggesting that host‐switching has occurred. Parasites can play powerful roles in interspecific relationships, influence species interactions, and even impact ecosystem functioning. The ability of parasites to host switch could further influence community interactions in this system, particularly if H. japonica continues to spread in North America. Further research is needed to evaluate how parasites (or lack thereof) may mediate the interactions and demographics of indigenous and non‐indigenous species in invaded ranges.

New survey of Clare Island. Volume 9: Birds ed. by T.K. Kelly

Reviewed by: New survey of Clare Island. Volume 9: Birds ed. by T.K. Kelly Joe Furphy New Survey of Clare Island. Volume 9: Birds T.K. Kelly (ed.) (Royal Irish Academy; 166 pp; €35) ISBN: 978–1–911479–41–3 Any published work must be seen as a picture of a particular time and place, but one of the strengths of New Survey of Clare Island. Volume 9: Birds is the way in which comparisons are made with other locations and species. While it is particularly interesting to see the tables in the Appendices giving comparative statistics for several Irish islands, for many readers their fascination will be with the unanswered questions on bird population make-up and the differences between Clare Island and other islands, especially where habitats, food resources and land use etc., appear superficially similar. An early chapter lists the avian species so far recorded on Clare Island. Some are given longer descriptions, contributing towards an understanding of relationships not only inter-specifically, but also spatially in relation to the situation on the nearby mainland, although few direct comparisons to topography or land use are made. The Clare Island avifauna benefits from a lack of general human interference; only two species are listed as deliberate introductions: Canada goose Branta canadensis and Pheasant Phasianus colchius; ironically, throughout Europe both species are often unwelcome; questions therefore need to be asked about their effects on the native populations on Clare Island. Separate chapters are devoted to seabirds, land birds and water birds. The seabirds chapter raises several interesting and relevant questions regarding the population dynamics of several species. Contrasts with population changes in other seabird colonies not only make interesting reading but also pose questions as to why there is so much variation in numbers in colonies that externally appear similar in terms of habitat and available food supplies. By way of example, Gannets did not nest on Clare Island until 1978 but the numbers have dramatically increased, while the number of Fulmars, similarly open-sea feeders and cliff-nesters, has decreased. Fortunately, there have been several national and European censuses of seabirds, so there are sufficient data available to allow basic comparisons to be made and research projects instituted to ascertain reasons for such discrepancies. However, a full analysis of the causes for fluctuations in bird population requires evidence from a large range of parameters, several of which are not readily available. In considering the distribution and population changes in land birds, proximity to the mainland is a factor, and it is postulated that the changes on Clare Island may be related to fluctuations on the adjacent Mayo shores. Much of the land area of Ireland has been subject to changes in land use and land management, factors with profound effects on the distribution and population dynamics of land birds. Clare Island is fortunate in that it has been spared most of the recent changes, with the result that bird numbers and their distribution can be related much more to naturally induced fluctuations than in most of mainland Ireland. The major 21st-century survey involved a series of transects, after which estimates were made of the populations of the various species throughout the island. Most groups are open-habitat and generalist species, and it is noted that hole-nesting birds are absent, despite the presence of woodland. The absence of rooks is similarly remarked upon, and a chapter devoted to examining possible reasons for this concludes that the island is simply not large enough to sustain a colony of this species. The limitations of conducting detailed survey work on farmland are mentioned, especially the necessity to avoid walking on cropped land or through flocks of animals. A chapter is devoted to the land birds (excepting raptors) of other Irish islands. As well as producing a series of fascinating graphs, diagrams and lists, we learn about the difficulties in making accurate deductions on many aspects of the inter-island contrasts, due to the lack of statistics on which any conclusions can be based. The chapter on waterbirds highlights the difficulties in surveying breeding populations in certain locations, partly due to the secretive behaviour of several species during the...

Growth-enhanced salmon modify stream ecosystem functioning.

Use of fast-growing domesticated and/or genetically modified strains of fish is becoming increasingly common in aquaculture, increasing the likelihood of deliberate or accidental introductions into the wild. To date, their ecological impacts on ecosystems remain to be quantified. Here, using a controlled phenotype manipulation by implanting growth hormone in juvenile Atlantic salmon (Salmo salar), we found that growth-enhanced fish display changes in several phenotypic traits known to be important for ecosystem functioning, such as habitat use, morphology and excretion rate. Furthermore, these phenotypic changes were associated with significant impacts on the invertebrate community and key stream ecosystem functions such as primary production and leaf-litter decomposition. These findings provide novel evidence that introductions of growth-enhanced fish into the wild can affect the functioning of natural ecosystems and represent a form of intraspecific invasion. Consequently, environmental impact assessments of growth-enhanced organisms need to explicitly consider ecosystem-level effects.

Detailed assessment of the reported economic costs of invasive species in Australia

The legacy of deliberate and accidental introductions of invasive alien species to Australia has had a hefty economic toll, yet quantifying the magnitude of the costs associated with direct loss and damage, as well as for management interventions, remains elusive. This is because the reliability of cost estimates and under-sampling have not been determined. We provide the first detailed analysis of the reported costs associated with invasive species to the Australian economy since the 1960s, based on the recently published InvaCost database and supplementary information, for a total of 2078 unique cost entries. Since the 1960s, Australia has spent or incurred losses totalling at least US$298.58 billion (2017 value) or AU$389.59 billion (2017 average exchange rate) from invasive species. However, this is an underestimate given that costs rise as the number of estimates increases following a power law. There was an average 1.8–6.3-fold increase in the total costs per decade since the 1970s to the present, producing estimated costs of US$6.09–57.91 billion year-1 (all costs combined) or US$225.31 million–6.84 billion year-1 (observed, highly reliable costs only). Costs arising from plant species were the highest among kingdoms (US$151.68 billion), although most of the costs were not attributable to single species. Of the identified weedy species, the costliest were annual ryegrass (Lolium rigidum), parthenium (Parthenium hysterophorus) and ragwort (Senecio jacobaea). The four costliest classes were mammals (US$48.63 billion), insects (US$11.95 billion), eudicots (US$4.10 billion) and monocots (US$1.92 billion). The three costliest species were all animals – cats (Felis catus), rabbits (Oryctolagus cuniculus) and red imported fire ants (Solenopsis invicta). Each State/Territory had a different suite of major costs by species, but with most (3–62%) costs derived from one to three species per political unit. Most (61%) of the reported costs applied to multiple environments and 73% of the total pertained to direct damage or loss compared to management costs only, with both of these findings reflecting the availability of data. Rising incursions of invasive species will continue to have substantial costs for the Australian economy, but with better investment, standardised assessments and reporting and coordinated interventions (including eradications), some of these costs could be substantially reduced.

Invasive Species in Puerto Rico: The View From El Yunque

Native flora and fauna of Puerto Rico have a long biogeographic connection to South America. Theory and empirical evidence suggest that islands, particularly those distantly isolated from the mainland, should be more susceptible to naturalizations and invasions of non-native species than continental areas. Anthropogenic disturbances can facilitate accidental and deliberate introductions of non-native species. In this study, we asked: What is the current status of introduced species within El Yunque National Forest (EYNF), the largest and most well-conserved forest area of Puerto Rico? To address this question, we reviewed the literature and surveyed local experts to identify introduced plant and animal taxa that are behaving as invaders within EYNF. We hypothesized that well-conserved forest areas within EYNF would be more resistant to invasions than disturbed areas along roads and ruderal areas with a long history of human activity. We found that there is only partial evidence that supports our hypothesis and this evidence is strongest in vascular plants, but not for the other taxonomic groups analyzed. Our combined results showed that currently the more ubiquitous invasive species in EYNF include some mammals (feral cat, rat, and mongoose) and some invertebrates (earthworms, mosquito, and Africanized honeybee). For many taxa, there is little information to thoroughly test our hypothesis, and thus more detailed surveys of the status of non-native and invasive species in EYNF are needed.

Potential invasion range of raccoon in Iran under climate change

Growing global evidence demonstrates that not only the invasion of alien species has imposed serious threats to native biodiversity, but it also threatens health and economics. The raccoon (Procyon lotor), medium-sized mammal, native to North America, as a result of escapes or deliberate introductions in the mid-twentieth century, is now distributed across much of mainland Europe and the Caucasus and known as an alien invasive species. The raccoon was observed and reported for the first time in 1991 in the Caspian Hyrcanian mixed forests ecoregion in Iran, near the border of Azerbaijan. Although it has been almost three decades since the first report in the northwest of the country, there are not many official reports nor scientific research on its dispersal and adaptive behaviour. In this study, we provide new evidence on the current distribution range and predict the potential distribution range and thus invasion risk of the raccoon under climate change in Iran. We trained an ensemble of species distribution models trained in native and European invaded range and transferred it over space and time to Iran in 6 future climate scenarios. We also calculated the potential dispersal range of the raccoon per year and explored potential invasion corridors. Our results show that the raccoon inclined to expand in the forests and rangelands near the Caspian Sea and toward west Iran. Our work provides evidence to conservationists and decision-makers to further focus on the areas where the species will most likely expand, under the future scenarios of the climate change in 2050.

Recording plant status and regeneration during single visits

Information on the origin (status) and regeneration of plant species improves our understanding of native distributions and the establishment of non-native species. However, current categories used to record status in Britain and Ireland, whilst conceptually informative, rely on a knowledge of persistence that is impossible to assess objectively during a single (one-off) recording visit. We propose five alternative categories that focus on origin (how a species arrived at a site) rather than persistence. The first two categories apply to nationally native taxa: (1) populations that are unequivocally native and (2) those that are likely to have been introduced and/or are spreading for reasons that are obscure. The other three categories cover the occurrences of any taxon, native or non-native, that is known or suspected to have been introduced to a site: (3) introductions with unknown/obscure origins; (4) deliberate introductions; and (5) accidental introductions. For the introduced categories 3-5 we recommend that botanists also record signs of regeneration, i.e. seedlings or widely scattered patches, as a more objective measure whether a species is likely to be self-sustaining in a given locality.

Changes in the abundance and diversity of earthworms in hill soils under different long-term fertiliser and sheep stocking regimes

ABSTRACT This study examined the earthworm community in permanent pastures at three self-contained farmlets that make up the long-term P fertiliser and sheep grazing study located at Ballantrae Hill Country Research Station. Thirty five years after the study was established, earthworm abundance was lower at the farmlet receiving no fertiliser since 1979 (LFNF, 219 m−2), compared to that receiving 125 kg SSP/ha/year (LFLF, 384 m−2) or 375 kg SSP/ha/year (HFHF, 428 m−2). Earthworm species diversity increased from two in 1979, to nine in 2014, as a result of both accidental and deliberate anthropogenic earthworm introductions. Across all farmlets earthworm abundance was closely associated with pasture production, as well as several pasture attributes and soil variables, particularly those influenced by slope. Maximising the contribution of soil fauna to soil function in hill country requires recognising the influence of slope on earthworm habitats and associated resource availability.

A taxonomic revision of the whitefish of Lakes Brienz and Thun, Switzerland, with description of three new species.

Event Abstract Back to Event A taxonomic revision of the whitefish of Lakes Brienz and Thun, Switzerland, with description of three new species. Oliver M. Selz1, 2*, Ole Seehausen1, 2, Carmela J. Dönz1, 2 and Pascal Vonlanthen1, 3 1 Centre of Ecology, Evolution and Biogeochemistry, Swiss Federal Institute of Aquatic Science and Technology, Switzerland 2 University of Bern, Switzerland 3 Aquabios GmbH, Switzerland The European whitefish (Coregonus spp.) provide prime examples of postglacial adaptive radiations with up to six species occurring in a single lake of the prealpine region. Despite this enigmatic species richness, approximately one-third of the species diversity in Swiss Lakes has not yet been taxonomically resolved. Here we review and revise the alpha taxonomy of the endemic whitefish of Lakes Brienz and Thun, Switzerland. We evaluate the status of six known species, of which three have been previously described. With a combination of species-targeted and habitat-randomised fishing surveys during or outside of the spawning season we are able to reveal with an integrative taxonomic approach of combining genetic assignments with morphological and meristic traits and multivariate statistical methods six whitefish species. Four species occur in both lakes Thun and Brienz and two species, a profundal specialist and a species of partial allochthonous origin, are unique to Lake Thun. Despite many past and present anthropogenic pressures, Lakes Thun and Brienz today harbour the most speciose whitefish radiation of the prealpine region. We further show that two of these species are present in Lake Biel, which has been artificially connected downstream of the lakes Thun and Brienz through the Aare river approx. 150 years ago. This work highlights that species delineation and description in such rich radiations requires an integrative approach to taxonomy, combining morphology with genetics and ecology and large contemporary and historical specimen collections. Such work is also much needed for conservation-minded fisheries management because human-made changes to the connectivity of water bodies as well as deliberate introductions, are increasing the distribution ranges of species and cause previously isolated biota to mix. Keywords: Coregonus, Salmonidae, Whitefish, adaptive radiation, ecological speciation, Integrative taxonomy Conference: XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019. Presentation Type: Oral Topic: TAXONOMY, PHYLOGENY AND ZOOGEOGRAPHY Citation: Selz OM, Seehausen O, Dönz CJ and Vonlanthen P (2019). A taxonomic revision of the whitefish of Lakes Brienz and Thun, Switzerland, with description of three new species.. Front. Mar. Sci. Conference Abstract: XVI European Congress of Ichthyology. doi: 10.3389/conf.fmars.2019.07.00112 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 05 Jun 2019; Published Online: 14 Aug 2019. * Correspondence: Dr. Oliver M Selz, Centre of Ecology, Evolution and Biogeochemistry, Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, 6047, Switzerland, oliver.selz@eawag.ch Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Oliver M Selz Ole Seehausen Carmela J Dönz Pascal Vonlanthen Google Oliver M Selz Ole Seehausen Carmela J Dönz Pascal Vonlanthen Google Scholar Oliver M Selz Ole Seehausen Carmela J Dönz Pascal Vonlanthen PubMed Oliver M Selz Ole Seehausen Carmela J Dönz Pascal Vonlanthen Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Palmageddon: the wasting of ornamental palms by invasive palm weevils, Rhynchophorus spp.

Urban areas landscaped with ornamental palms, especially Canary Islands date palms (Phoenix canariensis), are particularly vulnerable to incursion by invasive palm weevils, Rhynchophorus spp. (Coleoptera: Curculionidae). Metropolitan palmscapes are often resource rich in terms of palm species diversity and density, and these areas typically have numerous conduits (e.g., air, road, or sea transportation hubs) that assist with international and regional trade and tourism which can facilitate accidental or deliberate weevil introductions. Once established in urban areas, Rhynchophorus populations may be hard to suppress, from where they can expand their range and threaten agricultural commodities or native palms in wilderness areas. Here, we review current knowledge about relationships between Rhynchophorus invasions and urban environments. Further research areas should be addressed to improve forecasts of invasion risks and to complement management options for detection and control. We propose that greater attention be paid to quarantine restrictions on live palm movements and pro-active early detection and monitoring programs in areas deemed to be at high risk of invasion and establishment. In response to an incursion, we advocate the deployment of containment and eradication campaigns in urban zones when populations are small and highly localized.

Piscivore Diet Shifts and Trophic Level Change after Alewife Establishment in Lake Champlain

AbstractInvasions and deliberate introductions of new prey species are likely to affect the prey choice and trophic level of resident predators. Rainbow Smelt Osmerus mordax and Alewife Alosa pseudoharengus are common prey fish species in lakes throughout North America, either as native or nonnative species. The establishment of Alewives in the 2000s in a lake with a native Rainbow Smelt population (Lake Champlain) presented an opportunity to study changes in the diet and trophic level of fish already established in the system. Using stable isotope analysis, we found that Alewives became a major component of predator diets, in particular of the diets of Atlantic Salmon Salmo salar and Walleye Sander vitreus. Lake Trout Salvelinus namaycush consumed relatively few Alewives. For Walleyes (the predator with both pre‐ and post‐Alewife isotope ratios available), the δ15N values decreased significantly from the pre‐Alewife period of the late 1990s, indicating that Walleyes feed at lower trophic levels when Alewives are present. Predation on Alewives was correlated with the amount of spatial overlap of predators and prey. Our results show that the introduction of Alewives has altered the predator–prey linkages in Lake Champlain, alterations that can have major effects on food web structure and trophic cascades.

A simple, rapid method for detecting seven common invasive fish species in Europe from environmental DNA

Abstract Biological invasions are a global threat to biodiversity, and many arise from deliberate introductions. The American freshwater fish Micropterus salmoides and Ameiurus spp. (Ameiurus melas and Ameiurus nebulosus) were introduced to Europe for recreational fishing, Gambusia holbrooki and Gambusia affinis were introduced for mosquito population control, and Lepomis gibbosus was introduced as an ornamental species. The Asiatic Pseudorasbora parva was acquired inadvertently as an accompanying species in fish consignments. This article presents a novel approach for detecting these species directly from water samples based on a panel of five taxon‐specific primers within 16S rDNA. The primers were validated from tissue, in aquarium experiments, and from Ebro River water samples (Spain). With a simple polymerase chain reaction (PCR) protocol, followed by visualization in agarose gel or capillary electrophoresis, it was possible to detect these species from environmental DNA concentrations as low as 0.89–100 pg mL–1. This sensitive and economical tool can be used to control European invasions of these species and to preserve native biodiversity.

A long-term study (1949–2015) of the aftermaths of the deliberate experimental introduction of an invasive freshwater amphipod (Crustacea) to a small Island

The ability to track changing distributions and long-term inter actions between native and introduced species provides insights into forecasting impacts of invaders. We used data from deliberate field introduction experiments of a freshwater Gammarus amphipod (Crustacea) to the rivers of a small British island, The Isle of Man. The deliberate introductions commenced in 1949 and re-sampling occurred in the ‘60s, ‘70s ‘80s, ‘90s, 200 5 and finally in 2015. The findings generally confirmed the failure of introductions of Gammarus pulex into sites previously dominated by the native Gammarus duebeni celticus even with high propagule pressure in terms of numbers of individual invaders released and repeated introductions. Despite this, the island-wide 2015 survey revealed that G. d. celticus occurred in fewer sites and G. pulex in more sites than a decade earlier, indicating at this island-wide scale, the displacement of G. pulex by G. d. celticus seems to be continuing. In addition, one of the introduction sites, Arbory Stream which contained G. d. celticus from 1951–2005 contained only G. pulex in 2015, showing that even after six decades, assumptions cannot be made as to the limits of invader range expansion. Multivariate analysis of physico-chemical data from the 2015 island-wide sur vey revealed water quality as a crucial environmental gradient that influences the distributions of the native and invader species, with the former in higher organic water quality sites than sites with the invader or where invader and native co-occurred. The North American amp hipod Crangonyx pseudogracilis had expanded its range since 2005, including invading low biological water quality sites previously devoid of both Gammarus spp.. Pollution from historic metal mining is implicated as a potential major factor excluding amphipods. This deliberate ecological experiment, through long-term monitoring, continues to provide insights into the factors determining the distributions of natives and invaders.

Climate matching drives spread rate but not establishment success in recent unintentional bird introductions

Understanding factors driving successful invasions is one of the cornerstones of invasion biology. Bird invasions have been frequently used as study models, and the foundation of current knowledge largely relies on species purposefully introduced during the 19th and early 20th centuries in countries colonized by Europeans. However, the profile of exotic bird species has changed radically in the last decades, as birds are now mostly introduced into the invasion process through unplanned releases from the worldwide pet and avicultural trade. Here we assessed the role of the three main drivers of invasion success (i.e., event-, species-, and location-level factors) on the establishment and spatial spread of exotic birds using an unprecedented dataset recorded throughout the last 100 y in the Iberian Peninsula. Our multimodel inference phylogenetic approach showed that the barriers that need to be overcome by a species to successfully establish or spread are not the same. Whereas establishment is largely related to event-level factors, apparently stochastic features of the introduction (time since first introduction and propagule pressure) and to the origin of introduced species (wild-caught species show higher invasiveness than captive-bred ones), the spread across the invaded region seems to be determined by the extent to which climatic conditions in the new region resemble those of the species' native range. Overall, these results contrast with what we learned from successful deliberate introductions and highlight that different management interventions should apply at different invasion stages, the most efficient strategies being related to event-level factors.