bluuebunny/crossref_metadata_2025_split huggingface dataset:
Feral sheep on Socorro Island: facilitators of alien plant colonization and ecosystem decay
Authors: Walter Hartmut S. , Levin Geoffrey A. 
Published: December 2008

ABSTRACTThe paper examines the role of feral sheep (Ovis aries) in facilitating the naturalization of alien plants and degrading a formerly robust and stable ecosystem of Socorro, an isolated oceanic island in the Mexican Pacific Ocean. Approximately half of the island is still sheep‐free. The other half has been widely overgrazed and transformed into savannah and prairie‐like open habitats that exhibit sheet and gully erosion and are covered by a mix of native and alien invasive vegetation today. Vegetation transects in this moderately sheep‐impacted sector show that a significant number of native and endemic herb and shrub species exhibit sympatric distribution patterns with introduced plants. Only one alien plant species has been recorded from any undisturbed and sheep‐free island sector so far.Socorro Island provides support for the hypothesis that disturbance of a pristine ecosystem is generally required for the colonization and naturalization of alien plants. Sheep are also indirectly responsible for the self‐invasion of mainland bird species into novel island habitats and for the decline and range contraction of several endemic bird species.
Argentine ants displace floral arthropods in a biodiversity hotspot
Authors: Lach Lori 
Published: December 2008

ABSTRACTArgentine ant (Linepithema humile (Mayr)) invasions are often associated with the displacement of ground‐dwelling arthropods. Argentine ant invasions can also exert other effects on the community through interactions with plants and their associated arthropods. For example, carbohydrate resources (e.g. floral or extrafloral nectar) may influence foraging behaviour and interactions among ants and other arthropods. In South Africa's Cape Floristic Region, Argentine ants and some native ant species are attracted to the floral nectar of Leucospermum conocarpodendron Rourke (Proteaceae), a native tree that also has extrafloral nectaries (EFNs). Despite having relatively low abundance in pitfall traps, Argentine ants visited inflorescences more frequently and in higher abundance than the most frequently observed native ants, Camponotus spp., though neither native nor Argentine ant floral foraging was influenced by the EFNs. Non‐metric multidimensional scaling revealed significant dissimilarity in arthropod communities on inflorescences with Argentine ants compared to inflorescences with native or no ants, with Coleoptera, Diptera, Hymenoptera, Arachnida, Orthoptera, and Blattaria all being underrepresented in inflorescences with Argentine ants compared to ant‐excluded inflorescences. Native honeybees (Apis mellifera capensis Eschscholtz) spent 75% less time foraging on inflorescences with Argentine ants than on inflorescences without ants. Neither Argentine ant nor native ant visits to inflorescences had a detectable effect on seed set of Le. conocarpodendron. However, a pollen supplementation experiment revealed that like many other proteas, Le. conocarpodendron is not pollen‐limited. Flower predation was negatively associated with increased ant visit frequency to the inflorescences, but did not differ among inflorescences visited by native and Argentine ants. Displacement of arthropods appears to be a consistent consequence of Argentine ant invasions. The displacement of floral arthropods by Argentine ants may have far‐reaching consequences for this biodiversity hotspot and other regions that are rich in insect‐pollinated plants.
Tracking biological invasions in space and time: elucidating the invasive history of the green alga Codium fragile using old DNA
Authors: Provan Jim , Booth David , Todd Nicola P. , Beatty Gemma E. , Maggs Christine A. 
Published: December 2008

ABSTRACTWith the advent of ‘ancient DNA’ studies on preserved material of extant and extinct species, museums and herbaria now represent an important although still underutilized resource in molecular ecology. The ability to obtain sequence data from archived specimens can reveal the recent history of cryptic species and introductions. We have analysed extant and herbarium samples of the highly invasive green alga Codium fragile, many over 100 years old, to identify cryptic accessions of the invasive strain known as C. fragile ssp. tomentosoides, which can be identified by a unique haplotype. Molecular characterization of specimens previously identified as native in various regions shows that the invasive tomentosoides strain has been colonizing new habitats across the world for longer than records indicate, in some cases nearly 100 years before it was noticed. It can now be found in the ranges of all the other native haplotypes detected, several of which correspond to recognized subspecies. Within regions in the southern hemisphere there was a greater diversity of haplotypes than in the northern hemisphere, probably as a result of dispersal by the Antarctic Circumpolar Current. The findings of this study highlight the importance of herbaria in preserving contemporaneous records of invasions as they occur, especially when invasive taxa are cryptic.
Tolerance to herbivory, and not resistance, may explain differential success of invasive, naturalized, and native North American temperate vines
Authors: Ashton Isabel W. , Lerdau Manuel T. 
Published: December 2008

ABSTRACTNumerous hypotheses suggest that natural enemies can influence the dynamics of biological invasions. Here, we use a group of 12 related native, invasive, and naturalized vines to test the relative importance of resistance and tolerance to herbivory in promoting biological invasions. In a field experiment in Long Island, New York, we excluded mammal and insect herbivores and examined plant growth and foliar damage over two growing seasons. This novel approach allowed us to compare the relative damage from mammal and insect herbivores and whether damage rates were related to invasion. In a greenhouse experiment, we simulated herbivory through clipping and measured growth response. After two seasons of excluding herbivores, there was no difference in relative growth rates among invasive, naturalized, and native woody vines, and all vines were susceptible to damage from mammal and insect herbivores. Thus, differential attack by herbivores and plant resistance to herbivory did not explain invasion success of these species. In the field, where damage rates were high, none of the vines were able to fully compensate for damage from mammals. However, in the greenhouse, we found that invasive vines were more tolerant of simulated herbivory than native and naturalized relatives. Our results indicate that invasive vines are not escaping herbivory in the novel range, rather they are persisting despite high rates of herbivore damage in the field. While most studies of invasive plants and natural enemies have focused on resistance, this work suggests that tolerance may also play a large role in facilitating invasions.
Alien spider introductions to Europe supported by global trade
Authors: Kobelt Manuel , Nentwig Wolfgang 
Published: December 2008

ABSTRACTGlobal trade is permanently ongoing and increases its volume every year. In this study, the occurrence of 87 unintentionally introduced spider species alien to Europe is analysed. The analysis includes (1) the introduction potential of six different origin areas of the world according to trade volume, area size, and geographical distance; (2) the body size of native and alien species; and (3) occurrence in or at buildings (synanthropic) or in natural habitats. We found the eastern Palearctic as the most influencing origin area with 44 introduced spider species to Europe. The eastern Palearctic and the Indomalayan provided a significantly higher number of introductions than expected, whereas the Nearctic, Neotropical, and Afrotropical provided a significantly lower number of introduced species than expected. This can be explained with their lower trade volume, smaller area, larger geographical distance to Europe, and stronger climate differences to Europe. Comparing the body size of introduced and native European spider species of the same family, we found for Theridiidae significantly larger alien spiders and for all other tested families a trend to a larger body size of alien species compared to the native spiders. The family affiliation of alien spiders is the most important factor for synanthropic occurrence in Europe. On the base of a very conservative estimation of spider species introductions to Europe combined with possible effects of climate change, we predict for the near future a permanent increase in the number of alien spider species in Europe.
Tracing recent invasions of the Ponto‐Caspian mysid shrimp Hemimysis anomala across Europe and to North America with mitochondrial DNA
Authors: Audzijonyte Asta , Wittmann Karl J. , Väinölä Risto 
Published: December 2008

ABSTRACTThe mysid crustacean Hemimysis anomala (‘bloody‐red shrimp’) is one of the most recent participants in the invasion of European inland waters by Ponto‐Caspian species. Recently the species also became established in England and the Laurentian Great Lakes of North America. Using information from mitochondrial cytochrome oxidase I (COI) gene sequences, we traced the invasion pathways of H. anomala; the inferences were enabled by the observed phylogeographical subdivision among the source area populations in the estuaries of the Ponto‐Caspian basin. The data distinguish two routes to northern and western Europe used by distinct lineages. One route has been to and through the Baltic Sea and further to the Rhine delta, probably from a population intentionally introduced to a Lithuanian water reservoir from the lower Dnieper River (NW Black Sea area) in 1960. The other lineage is derived from the Danube delta and has spread across the continent up the Danube River and further through the Main–Danube canal down to the Rhine River delta. Only the Danube lineage was found in England and in North America. The two lineages appear to have met secondarily and are now found intermixed at several sites in NW Europe, including the Rhine and waters linked with the man‐made Mittellandkanal that interconnects the Rhine and Baltic drainage systems.
Estimating the invasion success of introduced plants
Authors: Caley Peter , Groves Richard H. , Barker Robyn 
Published: December 2008

ABSTRACTWe present methods for estimating the base proportion of introduced alien species that will naturalize, and the distribution of time until naturalization occurs. The approach is Bayesian, incorporating prior estimates of the probability of naturalization and the time from introduction to naturalization. A worked example uses data on the introduction and time to recorded naturalization of woody perennials introduced to South Australia. Up until 2007, 188 of 2230 (8.4%) woody perennials listed in nursery catalogues between 1843 and 1985 were recorded as having naturalized. If prior information on naturalization rates from elsewhere is ignored, the available data suggest that the most likely proportion of introduced plants that will naturalize is large (0.93) though uncertain (95% CI 0.51–0.99), with the corresponding mean time to recorded naturalization being protracted (522 years) and similarly uncertain (95% CI 360–678 years). Alternatively, if informative prior estimates of both the naturalization probability and the time to recorded naturalization are incorporated, the most likely probability of naturalization is estimated to be 18.6% (95% CI 15.5–23.4%). For those plants that do naturalize, the most likely value for the mean time from importation to recorded naturalization is 149 years (95% CI 130–174 years). Our results illustrate the potentially long timescale of the naturalization process, and the challenges this presents for obtaining accurate estimates of naturalization parameters.
Predicting the number of ecologically harmful exotic species in an aquatic system
Authors: Ricciardi Anthony , Kipp Rebekah 
Published: December 2008

ABSTRACTMost introduced species apparently have little impact on native biodiversity, but the proliferation of human vectors that transport species worldwide increases the probability of a region being affected by high‐impact invaders – i.e. those that cause severe declines in native species populations. Our study determined whether the number of high‐impact invaders can be predicted from the total number of invaders in an area, after controlling for species–area effects. These two variables are positively correlated in a set of 16 invaded freshwater and marine systems from around the world. The relationship is a simple linear function; there is no evidence of synergistic or antagonistic effects of invaders across systems. A similar relationship is found for introduced freshwater fishes across 149 regions. In both data sets, high‐impact invaders comprise approximately 10% of the total number of invaders. Although the mechanism driving this correlation is likely a sampling effect, it is not simply the proportional sampling of a constant number of repeat‐offenders; in most cases, an invader is not reported to have strong impacts on native species in the majority of regions it invades. These findings link vector activity and the negative impacts of introduced species on biodiversity, and thus justify management efforts to reduce invasion rates even where numerous invasions have already occurred.
Effect of propagule pressure on the establishment and spread of the little fire ant Wasmannia auropunctata in a Gabonese oilfield
Authors: Mikheyev Alexander S. , Tchingnoumba Landry , Henderson Ann , Alonso Alfonso 
Published: December 2008

ABSTRACTWe studied the effect of propagule pressure on the establishment and subsequent spread of the invasive little fire ant Wasmannia auropunctata in a Gabonese oilfield in lowland rain forest. Oil well drilling, the major anthropogenic disturbance over the past 21 years in the area, was used as an indirect measure of propagule pressure. An analysis of 82 potential introductions at oil production platforms revealed that the probability of successful establishment significantly increased with the number of drilling events. Specifically, the shape of the dose–response establishment curve could be closely approximated by a Poisson process with a 34% chance of infestation per well drilled. Consistent with our knowledge of largely clonal reproduction by W. auropunctata, the shape of the establishment curve suggested that the ants were not substantially affected by Allee effects, probably greatly contributing to this species’ success as an invader. By contrast, the extent to which W. auropunctata spread beyond the point of initial introduction, and thus the extent of its damage to diversity of other ant species, was independent of propagule pressure. These results suggest that while establishment success depends on propagule pressure, other ecological or genetic factors may limit the extent of further spread. Knowledge of the shape of the dose–response establishment curve should prove useful in modelling the future spread of W. auropunctata and perhaps the spread of other clonal organisms.
Fifty years of invasion ecology – the legacy of Charles Elton
Authors: Richardson David M. , Pyšek Petr 
Published: December 2008

ABSTRACTThe publication, in 1958, of Charles Elton's book The ecology of invasions by animals and plants launched the systematic study of biological invasions. Invasion ecology has grown to become an important multi‐disciplinary subfield of ecology with growing links to many other disciplines. This paper examines the citation history of Elton's book using the Web of Science. We also examine Elton's influence in shaping the current research agenda in invasion ecology, for which we use the 28 papers in a special issue of Diversity and Distributions (Volume 14: 2) as a representative sample.After 50 years, Elton's book remains the most cited single source in the field (> 1500 citations), and is cited more often every year (> 100 times) than any other invasion‐related publication, including influential papers in journals. Most citations to Elton's book refer to particular topics/concepts covered in the book, rather than citing it as a general reference about invasions. The shift in the distribution of topics/concepts cited with reference to Elton over time follows the same trend as for biogeography and ecology in general (increasing emphasis on analytical studies, multi‐scale analyses, multi‐disciplinary studies, etc.).Some topics emphasized by Elton are still the focus of current research (dispersal and spread of invasive organisms, impact on biodiversity, role of disturbance and enemy release) but several prominent themes in modern studies were not addressed by Elton. The emergence of new themes can be attributed to a general change in approach and emphasis underpinning research questions in conservation biogeography and applied ecology over the last half century (risk analysis, multi‐scale comparisons, propagule pressure, experimental approaches) and to the recent emergence and increasing availability of large data sets on the distribution of introduced species and to the emergence of key technologies (e.g. geographic information systems, modelling techniques, including niche‐based modelling, and molecular methods). Half a century after its publication, Charles Elton's book on invasions remains influential, but massive changes in the status of invasions and other environmental issues worldwide, together with advances in technology, are reshaping the game rules and priorities of invasion ecology.
Abstinence From Moderate Alcohol Self‐Administration Alters Progenitor Cell Proliferation and Differentiation in Multiple Brain Regions of Male and Female P Rats
Authors: He Jun , Overstreet David H. , Crews Fulton T. 
Published: December 2008

Background: Acute and chronic ethanol exposure has been found to decrease hippocampal neurogenesis, reduce dendritic differentiation of new neurons, and increase cell death. Interestingly, abstinence from such treatment increases hippocampal neurogenesis and microglial genesis across several brain regions. The goal of the current investigation was to study cellular alterations on neuro‐ and cell‐genesis during abstinence following alcohol self‐administration using alcohol‐preferring rats (P rats).Methods: Male and female P rats were given the choice of drinking 10% alcohol in water or pure water for 7 weeks. Social interaction behavioral assessments were conducted at 5 hours upon removal of alcohol, followed by bromo‐deoxyuridine (BrdU, 150 mg/kg × 1/d × 14 d) injections to label proliferating cells. Animals were then killed 4 weeks later to conduct immunohistochemical and confocal analyses using antibodies against BrdU and other phenotypic markers (NeuN for mature neurons; Iba‐1 for microglia; GFAP for astrocytes; and NG2for oligodendrocyte progenitors).Results: Mild alcohol withdrawal anxiety was detected by reduction in social interactions. The number of hippocampal BrdU+cells was increased approximately 50% during alcohol abstinence (26 ± 2.8 in controls vs. 39 ± 4 in alcohol group). BrdU+cells were also increased in the substantia nigra (SN) approximately 65% in the alcohol abstinent group (12 ± 1 in controls vs. 19 ± 1.5 in alcohol group). No gender differences were found. Confocal analyses indicated that approximately 75% of co‐localization of BrdU+cells with NeuN in the hippocampal dentate gyrus (DG) resulting a net increase in neurogenesis in the alcohol abstinent group compared to controls. In cingulum, greater proportion of BrdU+cells were co‐localized with NG2in the alcohol abstinent group indicating increased differentiation toward oligodendrocyte progenitors in both genders. However, the phenotype of the BrdU+cells in SN and other brain regions were not identified by NeuN, Iba‐1, GFAP, or NG2suggesting that these BrdU+cells probably remain in a nondifferentiated stage.Conclusions: These data indicate that abstinence from moderate alcohol drinking increases hippocampal neurogenesis, cingulate NG2differentiation, and SN undifferentiated cell proliferation in both males and females. Such cellular alteration during abstinence could contribute to the spontaneous partial restoration of cognitive deficits upon sobriety.
Real‐Time Identification of Serious Infection in Geriatric Patients Using Clinical Information System Surveillance
Authors: Meurer William J. , Smith Barbara L. , Losman Eve D. , Sherman Diana , Yaksich, RN Joseph D. , Jared Jeremy D. , Malani Preeti N. , Younger John G. 
Published: December 2008

OBJECTIVES: To develop and characterize an automated syndromic surveillance mechanism for early identification of older emergency department (ED) patients with possible life‐threatening infection.DESIGN: Prospective, consecutive‐enrollment, single‐site observational study.SETTING: A large university medical center with an annual ED census of 75,273.PARTICIPANTS: Patients aged 70 and older admitted to the ED and having two or more systemic inflammatory response syndrome (SIRS) criteria during their ED stay.MEASUREMENTS: A search algorithm was developed to screen the census of the ED through its clinical information system. A study coordinator confirmed all patients electronically identified as having a probable infectious explanation for their visit.RESULTS: Infection accounted for 28% of ED and 34% of final hospital diagnoses. Identification using the software tool alone carried a 1.63 relative risk of infection (95% confidence interval CI=1.09–2.44) compared with other ED patients sufficiently ill to require admission. Follow‐up confirmation by a study coordinator increased the risk to 3.06 (95% CI=2.11–4.44). The sensitivity of the strategy overall was modest (14%), but patients identified were likely to have an infectious diagnosis (specificity=98%). The most common SIRS criterion triggering the electronic notification was the combination of tachycardia and tachypnea.CONCLUSION: A simple clinical informatics algorithm can detect infection in elderly patients in real time with high specificity. The utility of this tool for research and clinical care may be substantial.