Biological invasions

Here in Hawaii, the only ones in the rat race are mongooses, along with Federal and State officials wanting to kill both rats and mongooses.  However, there is a big flaw in the recent Federal and State proposal for statewide eradication of Hawaii's rodents and mongooses, currently under review.  Here is the argument against eradication.

Several Melaleuca (Myrtaceae) species are invasive globally. Recently an increase in invasive species from this genus have been reported in South Africa. Here we document the first detailed assessment of the distribution and invasive potential of Melaleuca rugulosa in South Africa. We assess population structure, determine the current and potential future distribution in South Africa using climatic variables, conduct a risk analysis, provide recommendations for management, and consider the feasibility of eradication. We found one naturalising population of »665 individuals covering more than 1.2 hectares. It was first recorded in 1961 invading the native fynbos vegetation in the Table Mountain National Park (TMNP). Two recent fires in 2009 and 2016 likely enhanced spread, this spread happened despite undocumented clearing attempts in the last decade. The south-western Cape is the most climatically suitable for M. rugulosa, with most other wetter areas of the country being only partly suitable regions. The risk analysis indicated a medium risk, and we suggest listing M. rugulosa as category 1a (eradication target) under the South African National Environmental Management: Biodiversity Act (10/ 2004). Given the small area occupied, ease of access and the lack of a soil seed bank, the population can be extirpated from Devil’s Peak within the TMNP. We highlight that serotinous alien species, particular from the Myrtaceae, should receive more attention as potential invasive species in fire-driven ecosystems and that their lack of invasiveness in areas where fire is suppressed, should not be misinterpreted as being a low-risk species.

Abstract Here we report the first molecular data on an invasive Sinanodonta woodiana ( Lea, 1834 ) (Bivalvia: Unionidae) population from Lesser Sundas (Flores Island, Indonesia). The DNA barcoding reveals that this population belongs to a mitochondrial lineage that is widely distributed across Malaysia. The mean COI p -distance between this ‘tropical’ lineage and invasive European populations is 5.3 ± 1.0% which clearly corresponds to the interspecific difference. The representatives of such a ‘tropical’ lineage have likely invaded other Indonesian islands together with the introduction of their host fish species, because our sequenced specimens were taken from a population on the southeastern edge of the current Sinanodonta distribution. The molecular identification of invasive populations of the Chinese pond mussels using available online databases such as the BOLD IDS and NCBI's Genbank is doubtful, because there are at least seven distinct mitochondrial lineages, hence each of them could belong to a separate cryptic taxon.

As a result of recent collecting efforts and older unpublished data of one of us (AA), 32 ant species (including 2 morphospecies) new to the island of Sicily (Italy) were discovered. Seven of these taxa represent unequivocally exotic entities, whose discovery marks a decisive increase of this component in the local fauna. Among these, two forms of Nylanderia EMERY, 1906 are treated as morphospecies because of the problematic taxonomy of the genus. Six taxa among the discovered species are entirely new to the myrmecofauna of Italy. Finally, Tetramorium indocile SANTSCHI, 1927 is reported for the first time as a host for the social parasite Strongylognathus testaceus (SCHENCK, 1852). The state of the art of the Sicilian myrmecofauna, now counting about 150 species, is commented on.

A B S T R A C T Invasive stands of Prosopis (mesquite) cover over 6 million ha of South Africa and could invade over 56 million ha. These invasive stands have major impacts on biodiversity, local livelihoods and ecosystem services. We applied several methods to develop an objective basis for a national strategy to prioritise and guide the management of Prosopis. Decision trees were used for assigning different control objectives (prevention of spread to unoccupied areas, local eradication, containment and asset protection) to each of the 234 local municipalities in the country. Priority assets that require protection in densely invaded areas were identified, ranked and mapped (in order of importance: water source areas, biodiversity hotspots, and areas with high agricultural and rangeland potential). Available control methods were compared in terms of costs, effectiveness, and potential to create employment. Biological control and more mechanised approaches were identified as important and the role of control-through-utilisation requires urgent research. Scenario development suggests that integrated control would be most effective. Strategic guidelines for improving the management of Prosopis were produced. These guidelines discuss key needs and objectives for management, targets, time frames, indicators and monitoring programs, research needs and spatially prioritized management areas. Although the strategy proposed in this paper is specific to Prosopis in South Africa, the principles will be useful in other regions where Prosopis species are invasive, and more generally for other widespread invasive tree taxa.

Ailanthus altissima (tree of heaven) is a non-native invasive tree spreading within central Appalachia. This dioecious, deciduous, and allelopathic species copiously produces samaras, capable of traveling at least 200 m through primary wind-dispersal. Removal of A. altissima individuals prior to timbering and other forest disturbances may help prevent spread into forest interiors. To aid in species management, this study investigated the use of remote sensing to identify the location and abundance of samaras in mixed mesophytic forests through supervised classifications. From empirical measurements, the estimated number of seeds per classified unit area was determined and the relationship between quantified propagule sources and individual seed primary dispersal was spatially modeled using a cellular automata model. The predicted seed dispersion pattern was compared to empirical seed trap measurements. Secondary seed dispersal, germination and seedling survival parameters were determined through field experiments. Specifically, I found that remote sensing can be successfully used to distinguish A. altissima samara clusters from surrounding closed canopy vegetation. The identified total area of classified A. altissima samara clusters was determined to be linearly related to total canopy seed yield, however model predictions of seed dispersal patterns generally predicted greater numbers of seeds per seed trap compared to measured outcomes. Seed dispersal predictions using all classified A. altissima samara clusters provided no positive relationships with observed values (Site II, p=0.2997; negative relationship at Site III, p=0.0053). Manually delineating seed sources through photo interpretation resulted in a positive relationship between model estimates and observed seed rain (Site II, p=0.0225), but may still contain commission errors (Site III, p=0.7002). Microsite survey observations of seed germination indicate the frequency of safe sites was high in disturbed environments (canopy gaps), but seedling survival was negligible in the year this study was performed. Measurements of secondary dispersal on land and water (hydrochory) indicate the species can be dispersed with multiple dispersal agents. Hydrochory was shown to be able to contribute greatly to the species’ long distance dispersal, as seeds can reach water bodies, stay viable for long periods of immersion, and can be dispersed downstream distances more than two orders of magnitude greater than primary dispersal. This was the first demonstration of hydrochory in this species. From these studies, it appears that polychory may contribute greatly to this species dispersal and I can infer the same polychory occurs in other terrestrial species, and may contribute to invasive success.

The American mink (Neovison vison) is a semi-aquatic, generalist carnivore released onto Tierra del Fuego (TDF) Island in the 1940s, subsequently spreading to adjacent islands in the archipelago with potential effects on native prey populations. Knowledge of this new predator’s trophic ecology is essential to identify threats, plan control strategies and conserve native fauna. We studied seasonal mink diet in TDF in different habitats. We identified undigested remains from 493 scats collected between May 2005 and March 2009 along marine coasts and freshwater shores (rivers and lakes). Small mammals and fish were the main mink prey in TDF (over 65% of diet items). Seasonal variations were not detected, but diet did vary significantly between marine and freshwater habitats, where more terrestrial items were consumed. Among mammals, mink consumed more small native rodents than exotic species. Native fish consumption was also important with greater representation of species from the families Nototheniidae and Galaxiidae in marine and freshwater habitats respectively. Birds were the third item in importance, but did not constitute a particularly large part of the mink’s diet on TDF. Overall, differences found in mink diet between habitats reflected their generalist/opportunistic feeding behaviour and did not differ greatly from observations in its native range or in other areas where it has been introduced. Our results establish the interactions between this novel predator and its prey and also illustrate the need to continue research on native prey populations to quantify mink impact on them and understand the ecological context of this biotic assemblage.

Admixture between differentiated populations is considered to be a powerful mechanism stimulating the invasive success of some introduced species. It is generally facilitated through multiple introductions; however, the importance of admixture prior to introduction has rarely been considered. We assess the likelihood that the invasive Ambrosia artemisiifolia populations of Europe and Australia developed through multiple introductions or were sourced from a historical admixture zone within native North America. To do this, we combine large genomic and sampling datasets analyzed with approximate Bayesian computation and Random Forest scenario evaluation to compare single and multiple invasion scenarios with pre- and post-introduction admixture simultaneously. We show the historical admixture zone within native North America originated before global invasion of this weed, and could act as a potential source of introduced populations. We provide evidence supporting the hypothesis that the invasive populations established through multiple introductions from the native range into Europe and subsequent bridgehead invasion into Australia. We discuss the evolutionary mechanisms that could promote invasiveness and evolutionary potential of alien species from bridgehead invasions and admixed source populations.

Exotic species can threaten biodiversity by disrupting ecological interactions among native species. Highly-attractive exotic species can exert a 'magnet effect' by attracting native pollinators, which may have either competitive or facilitative effects on co-flowering native plants. However, those effects may be context-dependent. We used a mistletoe-hummingbird pollination system in the Valdivian rainforest (southern Chile) to test whether the exotic tree Eucalyptus globulus (a highly attractive species to pollinators) acts as a magnet species, affecting the co-flowering native mistletoe. We compared humming-bird abundance, visitation rates, and activity patterns between native forest and abandoned E. globulus plantations. We found that hummingbirds were more abundant and visited more flowers at the plantation irrespective of E. globulus flowering. We observed a significant change of pollinator activity at the native habitat during E. globulus flowering, as hummingbirds visited mistletoe flowers more frequently early in the morning at the plantations and in the afternoon at the native forests. Our results showed that E. globulus acts as an exotic magnet species and can alter pollinator abundance and behavior. Our findings demonstrate the importance of considering local-and landscape-scale processes to understand the effects of magnet species on native plants and suggest that magnet species may influence even highly-attractive plants.

Non-native mammals are major drivers of ecosystem change and biodiversity loss; this is especially apparent on islands. However, techniques exist to remove non-native mammals, providing a powerful conservation tool. Conservation practitioners are now targeting larger islands for restoration. Leveraging existing and developing new techniques and technologies will prove critical to successful eradications on large islands. Using the removal of introduced goats (Capra hircus) from Santiago Island, Galápagos as a case study, we present a suite of Geographic Information System (GIS) tools that aid island conservation actions. GIS tools were incorporated into the three phases of the eradication campaign: planning, hunting, and monitoring. Further, these tools were adopted for three eradication techniques: ground-based hunting, aerial hunting by helicopter, and Judas goats. These geographic approaches provide a foundation for statistical, spatial, and economic analyses that should increase the capability and efficiency of removal campaigns. Given limited conservation funds and the dire status of many insular species, efficiently removing non-native mammals from islands is of paramount global conservation importance.

Invasive species often exhibit geographical variations in life history traits that may allow them to successfully invade different environments. We investigated geographical variation in body size and sexual size dimorphism (SSD) of invasive bullfrogs in southwestern China, by sampling two breeding populations (descendants of a single source population) inhabiting sites at low (1,412 m, Shiping) and high (2,692 m, Luguhu) altitudes. Both populations exhibited significant SSD, with females larger than males. At high altitude, mean body size of both sexes and the degree of SSD were significantly reduced; the reduction in mean body size with increasing altitude was more pronounced in females, although not significantly so. Female bullfrogs also showed a significant decrease in average age at high altitude that may be a major factor related to this pattern; average age of male bullfrogs did not vary significantly with altitude. Growth rate of both sexes was also lower at high altitude. Our results provide the first evidence that introduced bullfrog’s exhibit geographical variation in morphology in invaded areas in response to different environments, likely due to changes in climate. Additional research is required to determine the mechanism of this variation (i.e., physiological or developmental plasticity, mortality rate, selective pressure) and most importantly, to evaluate the potential for variation in the impacts of introduced bullfrogs on native ecosystems in China.

Two exotic fishes, common carp (Cyprinus carpio) and tilapia (Oreochromis niloticus), were introduced more than 20 years ago into Xochimilco for aquaculture, and now dominate the system in terms of biomass and numbers. Over this same period, wild populations of the microendemic axolotl salamander (Ambystoma mexicanum) have been dramatically reduced, and it currently persists in isolated areas of this aquatic system, which is situated at the edge of Mexico City. In this study, we examine potential trophic interactions and niche overlap among two exotic fishes: carp and tilapia, and the native axolotl. Axolotl had more diverse diets and a higher trophic position compared to the exotics. Stable isotope analysis revealed substantial trophic niche overlap among axolotl and the exotics. The two exotics occupied a larger niche area than the axolotl, suggesting higher levels of omnivory and diet specialization. Current exotic fish removal efforts will further our understanding of interactions between the axolotl and exotic species, and are expected to benefit axolotl recovery efforts.

A literature survey identified 403 primary research publications that investigated the ecological effects of invasive alien insects and/or the mechanisms underlying these effects. The majority of these studies were published in the last 8 years and nearly two-thirds were carried out in North America. These publications concerned 72 invasive insect species, of which two ant species, Solenopsis invicta and Linepithema humile, accounted for 18% and 14% of the studies, respectively. Most publications investigated effects on native biodiversity at population or community level. Genetic effects and, to a lesser extent, effects on ecosystem services and processes were rarely explored. We review the effects caused by different insect invaders according to: their ecosystem roles, i.e. herbivores, predators, parasites, parasitoids and pollinators; the level of biological organisation at which they occur; and the direct and indirect mechanisms underlying these effects. The best documented effects occur in invasive ants, Eurasian forest herbivores invasive in North America, and honeybees. Impacts may occur through simple trophic interactions such as herbivory, predation or parasitism. Alien species may also affect native species and communities through more complex mechanisms such as competition for resources, disease transmission, apparent competition, or pollination disruption, among others. Finally, some invasive insects, particularly forest herbivores and ants, are known to affect ecosystem processes through cascading effects. We identify biases and gaps in our knowledge of ecological effects of invasive insects and suggest further opportunities for research.

Several lines of evidence suggest that the effects of invasive speciesmay be greater in aquatic freshwaters than in terrestrial ecosystems.We argue that freshwaters are significantlymore invasible—from a number of poorly regulated sources—and also more susceptible to negative biodiversity, physical ecosystem, and socioeconomic impacts when invaded, than their terrestrial counterparts. Moreover, the nature
of freshwaters appears to result in impacts that are wide ranging and severe while being indirect, diffuse, and difficult to both detect and predict. For these reasons, we conclude that freshwater invasive species represent a special case,
when compared with terrestrial invasives, in which the likelihood of negative impacts, and their effects, is disproportionately severe. We suggest that future
approaches to research in this area should aim to audit the full array of impacts of a number of representative invasive species,with a view to building an evidence base
to support the global implementation of a precautionary approach to the release of aquatic freshwater non-native species.

Understanding the amount of impact and distribution of invasive species is important for both basic ecological research and making management decisions. Because of their extensive impacts in southern Patagonia, invasive North American beavers (Castor canadensis) are considered both a scientific and conservation priority. However, little is known about the landscape-scale effects of these exotic ecosystem engineers. Using satellite imagery, we estimated the impact of beavers in the Argentine portion of Tierra del Fuego Island and determined the habitat factors (vegetation cover, forest type, stream presence and topography) related to their presence using both non-parametric statistical and information-theoretic approaches. Results indicated that more than 31,000 ha (1.6 % of the study area) were impacted by beavers and that the presence, but not the amount, of beaver impacts were spatially clustered. Impacts were greater in the Mountain ecoregion (2.8 % of the ecoregion) and lower in the Steppe (0.1 %). The best model for predicting beaver presence included variables related to water availability (presence of peat-lands and streams), forage availability (forest type cover), and topography (slope and elevation). These findings support previous assertions that this invasion is the largest alteration to the sub-Antarctic forests in the Holocene. They also serve as a foundation for the development of maps based on habitat-and landscape-scale conditions to assist with the orientation of control, eradication, and restoration efforts currently being planned.

This article seeks to construct a comparative investigation of the role and application of militaristic metaphors in three contested areas of science-society discourse (invasive species, foot-and-mouth disease, and Severe Acute Respiratory Syndrome). It examines differences in the uses of metaphors and the role played by the emergence or neglect of critical linguistic engagement in these areas of public concern. It contributes to debates about the relationship between language use, policy, and the public understanding of science and technology. It demonstrates that militaristic metaphors are still part of a pervasive, but by no means inevitable, mode of science and policy communication.

A highly significant though often unrecognised dimension of globalisation is the movement of plant and animal species around the world. The increase in the movement of alien species is directly related to the growth in international trade and tourism and human mobility. However, the ecological, economic and social implications of such species transfer is little recognised in the tourism literature and, surprisingly, in discussions of sustainable tourism and tourism's contribution to conservation. This is remarkable given the scale of impacts that invasive species and diseases can have along with the measures put in place to prevent them. If a quarantine is applied then by definition mobility, and hence tourism, is prevented. Drawing on a range of sources the article provides an analysis of the relationship between tourism and biological exchange as well as the biosecurity methods that are put in place to prevent exchange and its impacts. The paper highlights the difficulties in applying some of these measures. The article concludes with noting the possible implications of forecast growth in international tourism for biological exchange including potential health and environmental concerns.

Key words: biodiversity conservation, biological exchange, biological invasion, invasive species, introduction pathways, antibiotic resistance

This is a draft version. For the authoritative version please consult the journal website.

Japanese honeysuckle (Lonicera japonica Thunb.) is a twining semi-evergreen vine native to Japan, Korea and eastern China. Over the past 150 yr it has been introduced as an ornamental and become established in temperate and tropical regions worldwide. It was first discovered in Canada in 1976 in southwestern Ontario woodlands and has since been found growing without cultivation in 15 localities. While L. japonica does not occur very frequently in southern Ontario, climate change models suggest that it may become more abundant in this region. Its predominance elsewhere derives from morphological and physiological characteristics that allow it to be particularly successful in the edge habitats of fragmented landscapes. Through extensive vegetative propagation and competitive ability it occupies space which may otherwise host a diverse native flora. The plant has many uses in Asian medicine and is a popular ornamental, but has been prohibited in some regions due to its displacement of ...

The wild boar is an invasive ecosystem
engineer in Argentina that has lacked sufficient basic
information to determine applied actions. The current
distribution, impacts and management of this species
were analyzed using the expert opinion surveys of
protected area managers. The boar is widely distributed and occupies most of Argentina’s terrestrial
ecoregions. Moreover, its populations are common,
and its abundance is growing in most of the protected
areas. Boars were recorded mostly in wetlands, forest
and shrublands. Managers also reported a wide range
of negative impacts, which included soil disturbance,
vegetation damage and animal predation. Several
control method types are used and in most protected
areas, more than one are applied, but hunting was the
most used technique. However, the effectiveness of
control methods was low, suggesting the need of an
urgent plan to define coordinated management actions
to minimize the negative impacts of this species and
also to prevent its expansion into new areas.

Understanding how invasive species affect key ecological interactions and ecosystem processes is imperative for the management of invasions. We evaluated the effects of invasive corals (Tubastraea spp.) on fish trophic interactions in an Atlantic coral reef. Remote underwater video cameras were used to examine fish foraging activity (bite rates and food preferences) on invasive cover levels. Using a model selection approach, we found that fish feeding rates declined with increased invasive cover. For Roving Herbivores (RH) and Sessile Invertivores (SI), an abrupt reduction of fish feeding rates corresponded with higher invasive cover, while feeding rates of Territorial Herbivores (TH) and Mobile Invertivores (MI) decreased linearly with cover increase. Additionally, some fish trophic groups, such as RH, SI and Omnivores (OM), had lower densities in reef sections with high invasive cover. These findings demonstrate that invasive corals negatively impact fish-benthic interactions, and could potentially alter existing trophic relationships in reef ecosystems.