Extinction Of Native Species Research Articles

Potential distribution of the tiger shrimp Penaeus monodon (Decapoda: Penaeidae), an invasive species in the Atlantic Ocean

Introduction: Invasive species are considered the second cause of extinction of native species after habitat loss. The impacts of invasive species have serious economic implications since the presence of this type of species can result in a decrease in ecosystem services granted to humans. In marine systems, some human activities such as maritime transport and aquaculture have favored the dispersion of invasive species, especially those with commercial importance. This paper describes the potential distribution of the tiger shrimp, Penaeus monodon, an invasive species along the American Atlantic coast. Objective: To describe a potential distribution model of Penaeus monodon in the American Atlantic region and compare the environmental characteristics of this region with those of the Indo-Pacific original niche conditions. Methods: Using geographic and environmental data, we constructed and tested three models to determine the efficiency of MaxEnt v. 3.3 software in predicting new areas for the distribution of this invasive shrimp species. Geographic data were downloaded from such web sites as the Global Biodiversity Information Facility, the Ocean Biogeographic Information System, and the United States Geological Survey, as well from literature. Environmental data were downloaded from Bio-Oracle v2.0 data base. The three tested models were: 1) the first was created using only recordings of Penaeus monodon from the Indo-Pacific (its origin zone) and then projected to the Atlantic (native model); 2) the second was built using only recordings from the invaded area; the training and projection area of this model was the Atlantic (invasive model); 3) the third included recordings from both the Indo-Pacific and Atlantic regions, and the model was trained and projected jointly in both areas (complete model). We extracted the values of the three models for each tiger shrimp sightings in the invaded area; sightings with values ³ 0.5 were considered as valid prediction of occurrence of the species. Results: We found that the following variables explained 80 % of species distribution: phosphates from the ocean surface, coastal type, chlorophyll a, and maximum bottom temperature. In terms of the models’ ability to predict the occurrences reported in the Atlantic, results were as follows: Native model had a prediction index of 40 %; Invasive model was able to predict 81 % of recordings; and complete model predicted 92 % of total occurrences reported in the invaded area. Conclusions: Our findings suggest that based on the complete model, the countries where the tiger shrimp could establish itself are Mexico and Cuba. Continuous monitoring and conservation actions are relevant in the countries where this species is currently established, as well of those countries with potential for invasions.

Biological invasions drive biotic homogenization of North American crayfishes

The invasion of non-native species, and declines or extinctions of native species, can act together to drive either biotic homogenization or differentiation between regions over time. To date, no studies have investigated whether high incidence of biological invasions, as well as high risk of extinction, among freshwater crayfishes has resulted in biotic homogenization consistent with other taxonomic groups globally. We used Jaccard’s dissimilarity index to calculate taxonomic beta diversity of native crayfishes between and within major regions of North America, the most species-rich region on the planet for these organisms, and subsequently decomposed beta diversity into its turnover and nestedness components. To estimate biotic homogenization or differentiation, we next added introduced and established non-native crayfishes to these beta diversity calculations, and then incrementally subtracted native crayfishes on a gradient of high to lower vulnerability to extinction. We found that North American native crayfishes have extremely high beta diversity between major geographic regions of this continent, driven by turnover rather than nestedness, whereas beta diversity and its components are more heterogenous within major geographic regions. Further, we found that biological invasions by introduced non-native crayfishes drive biotic homogenization, rather than differentiation, between all regions of North America, and this effect was substantially greater than that of potential future extinctions. Within major regions of North America, biological invasions resulted in either biotic homogenization or differentiation, although the magnitude of homogenization when present was greater than that of differentiation. Cumulatively, biological invasions by non-native crayfishes are driving biotic homogenization of North American crayfishes. Management interventions are urgently needed to protect native species and ecosystems from the negative effects of these invasive crayfishes, as well as to conserve the antiquity and novelty of crayfish communities across North America.

Multitemporal Remote Sensing Based on an FVC Reference Period Using Sentinel-2 for Monitoring Eichhornia crassipes on a Mediterranean River

Invasive aquatic plants are a serious global ecological and socio-economic problem because they can cause local extinction of native species and alter navigation and fishing. Eichhornia crassipes (water hyacinth) is a dangerous invasive floating plant that is widely distributed throughout the world. In Lebanon, it has spread since 2006 in the Al Kabir River. Remote sensing techniques have been widely developed to detect and monitor dynamics and extents of invasive plants such as water hyacinth over large areas. However, they become challenging to use in narrow areas such as the Al Kabir River and we developed a new image-analysis method to extract water hyacinth areas on the river. The method is based on a time series of a biophysical variable obtained from Sentinel-2 images. After defining a reference period between two growing cycles, we used the fractional vegetation cover (FVC) to estimate the water hyacinth surface area in the river. This method makes it possible to monitor water hyacinth development and estimate the total area it colonizes in the river corridor. This method can help ecologists and other stakeholders to map invasive plants in rivers and improve their control.

Invasive birds spread native seeds

Ecological Networks When humans introduce exotic species to sensitive ecosystems, invasion and extinction of native species often follow. The resulting ecological communities can develop unusual interactions between the survivors and newcomers. Vizentin-Bugoni et al. analyzed the structure of seed dispersal networks in Hawai'i, where native bird species have been mostly replaced by invaders. They found that the native plants now depend on the invasive birds for seed dispersal. The network of dispersal interactions is complex and stable, which are features of native seed-dispersal networks in other parts of the world. It appears that introduced species may, in some circumstances, become integrated into native ecosystems. Science , this issue p. [78][1] [1]: /lookup/volpage/364/78?iss=6435

Similarity in seasonal flow regimes, not regional environmental classifications explain synchrony in brown trout population dynamics in France

Abstract Investigating the variables driving synchrony in populations and the spatial scales at which they operate is worthwhile for both a basic understanding of population dynamics and for management. Various environmental classifications have been developed to group sites according to predefined similarities in abiotic variables (with spatial and/or temporal components) and to explain population dynamics in running waters. These classifications may be useful to managers and decision makers, as studies have shown relationships between time‐dependent population variability and environmental classifications on different spatial scales. We investigated whether synchrony among brown trout (Salmo trutta) populations could be explained by three regional (hydro‐ecoregions, hydrological units, and natural flow regime classification) and one local environmental classification and their associated variables. We first analysed whether densities of two size classes (0+ and >0+ fish) varied over a large spatial scale (i.e. 112 sites spread throughout France sampled for >11 years). We then determined whether the degree of synchrony matched the spatial patterns defined by the environmental classifications. Finally, we investigated whether variables such as river distance between sites, hydrology, and temperature were associated with patterns of synchrony. Overall, relationships observed between synchronies in environmental variables and trout population densities were weak. Synchrony was best explained by the classification based on hydrological units, defined as discrete physical units that provided boundaries with real biological significance for river assemblages (12% for 0+ density and 9% for >0+ density and total densities). However, when considering environmental variables alone, synchrony in trout populations was mainly associated (from 11% to 23%) with seasonal flow variables such as high flows during reproductive and emergence periods. Temperature and river distance did not explain synchrony between trout populations. High flows during emergence appear to be a key driver of brown trout population dynamics. Floods during the reproductive period could explain synchrony among brown trout populations, although the effect was weaker than that of high flows during the emergence period. We concluded that existing physical, morphological, and biogeographical classifications at regional spatial scales were not sufficiently integrative to account for environmental drivers (such as flow variables) that were most associated with the spatiotemporal patterns of synchrony in trout populations. Flow explained synchrony better than classifications did. Further investigations should focus on the spatial patterns of flow variations during the emergence and reproductive periods to derive geographical areas that best capture synchrony patterns in trout dynamics. This approach could be extended to other freshwater fish species for which climatic drivers are important, and may help to explain the distributional changes of exotic species, the propensity of populations to fluctuate synchronously and the scale of synchrony patterns under different scenarios of climate change, or the threat of extinction of native species if the Moran effect is high.

Exploring vascular flora diversity of two protected sandy coastal areas in southern Italy

Coastal ecosystems are among the world’s most threatened environments, as they undergo diverse anthropogenic pressures, which trigger habitat alteration along with rarefaction and/or local extinction of native species. In this study, we performed a floristic investigation aimed at assessing the environmental status of two protected sandy areas located on the Tyrrhenian coast of southern Italy, the southern Garigliano estuary area and Castel Volturno Nature Reserve. These localities show similar geomorphological and climatic conditions, but different land uses and management practices. The sampling of the vascular plants was carried out through geo-location of species, to allow their availability to national and international floristic mapping projects. At whole territory and habitat types level, major trends for shared and exclusive species composition were identified through the analysis of life form, chorology percentage spectrum and similarity index. We detected that the total vascular flora is composed by 429 species, and found out that Garigliano is slightly richer in species (317) than Castel Volturno (311). It is important to note that Garigliano and Castel Volturno’s richness in plants was considerably significant in comparison with other coastal areas of central and southern Italy. Furthermore, although we pointed out that the studied areas showed a low degree of floristic similarity, the shrubland habitat encompassed the highest number of total species and plants of floristic interest (i.e., Italian endemic, rare in Campania, plants included in CITES convention, Habitat Directive, Regional Law of Campania 40/94, National and Regional Red List) in both areas. Finally, despite a severe alteration due to direct anthropogenic disturbance and large-scale alterations that occurred in the last 60 years, we showed that several species of phytogeographical interest are still found in the studied coastal sandy areas, confirming the great importance of this territory for plant diversity and conservation.

Hybridization between an endangered freshwater fish and an introduced congeneric species and consequent genetic introgression.

Artificial transplantation of organisms and consequent invasive hybridization can lead to the extinction of native species. In Matsuyama, Japan, a native bitterling fish, Tanakia lanceolata, is known to form hybrids with another bitterling species, T. limbata, which was recently introduced from western Kyushu, Japan. These bitterlings spawn in the gills of two freshwater unionid species, Pronodularia japanensis and Nodularia douglasiae nipponensis, which have rapidly declined on the Matsuyama Plain in the past 30 years. To gauge the effect of invasive hybridization, we determined the genetic introgression between T. lanceolata and T. limbata and analyzed the morphology of these species and their hybrids to infer their niche overlap. We collected adult individuals of Tanakia spp. and genotyped them based on six microsatellite loci and mitochondrial cytochrome b sequences. We analyzed their meristic characters and body shapes by geometric morphometrics. We found that 10.9% of all individuals collected were hybrids. Whereas T. lanceolata were more densely distributed downstream and T. limbata were distributed upstream, their hybrids were widely distributed, covering the entire range of native T. lanceolata. The body height and anal fin length of T. limbata were greater than those of T. lanceolata, but their hybrids were highly morphologically variable, covering both parental morphs, and were widely distributed in the habitats of both parental species. Hybridization has occurred in both directions, but introduced T. limbata females and native T. lanceolata males are more likely to have crossed. This study shows that invasive hybridization with the introduced T. limbata is a potential threat to the native population of T. lanceolata via genetic introgression and replacement of its niche in streams.

Causes and consequences of crayfish extinction: Stream connectivity, habitat changes, alien species and ecosystem services

Abstract Given the ongoing decline of many species, it is important to perform multifactorial analyses of conservation status and to assess the effects of species extinction on ecosystem services. In this study, we used long‐term surveys to assess the influence of habitat change, landscape alteration and invasive species on extinction risk of the native crayfish Austropotamobius pallipes. We reviewed the existing literature to assess which ecosystem services are threatened by local extinction of A. pallipes and replacement with alien crayfish. We sampled 196 streams and wetlands in northern Italy. Of these, 117 received multiple surveys over a 13‐year period (2004–2017), thus allowing accurate measurement of extinction rate. Thirty‐four percent of A. pallipes populations underwent extinction between 2004 and 2017. The occurrence of alien crayfish in the catchment basin and urban growth in the landscape surrounding streams were associated with A. pallipes extinction. The probability of persistence was significantly higher in populations close to stream springs and with physical barriers (especially waterfalls) separating them from basins with alien crayfish. Extinction of native crayfish alters community structure and impairs regulating services such as detrital breakdown and pest regulation. Replacement by alien crayfish (Procambarus clarkii and Faxonius limosus) also threatens supporting and regulating services by altering nutrient cycling, food webs, sediments and erosion. The implementation of management practices that control river connectivity using selective barriers is needed to prevent further local extinction of native species. Integrating information on extinction with knowledge of impacts on ecosystem services is essential in developing more effective conservation policies.

Plant Diversity in Cities:Call for Assessment and Conservation

Urbanization destroys natural habitats, displaces native ecosystems and results in regional extinction of native species. Urbanization is also argued to cause homogenization during which native species are replaced with non-native species. Negative impact of urbanization on ecosystems and biodiversity is usually focused upon while the fact that high levels of biodiversity may flourish inside cities are frequently ignored. Cities comprise a mixture of remnants of the pre-existing urban habitats and new urban habitats. The remaining fragments of natural landscapes, and other vegetation areas constitute the green infrastructure supporting the biological diversity of cities. Several biotopes such as lawns, hedges, parklands and street trees occur in the cities. In the cities ambient temperatures are higher than those of the surrounding rural areas, exhibiting the phenomenon of urban heat island. Urban vegetation experiences longer growing seasons and exhibits earlier greening than vegetation in the surrounding rural areas. Trees comprise the natural capital assets for cities as they provide immense benefits and ecosystem services for the wellbeing of city dwellers, although there are some disservices also. Studies on urban vegetation are very few in the tropics and particularly in India. In this article we review several aspects of plant diversity in cities in order to sensitize scientists, city managers and lay public to the need for more research on socioeconomic benefits and costs of city vegetation and to augment the vegetation within cities through conservation.

Stress in biological invasions: Introduced invasive grey squirrels increase physiological stress in native Eurasian red squirrels.

Invasive alien species can cause extinction of native species through processes including predation, interspecific competition for resources or disease-mediated competition. Increases in stress hormones in vertebrates may be associated with these processes and contribute to the decline in survival or reproduction of the native species. Eurasian red squirrels (Sciurus vulgaris) have gone extinct across much of the British Isles and parts of Northern Italy following the introduction of North American invasive grey squirrels (Sciurus carolinensis). We extracted glucocorticoid metabolites from faecal samples to measure whether the presence of the invasive species causes an increase in physiological stress in individuals of the native species. We show that native red squirrels in seven sites where they co-occurred with invasive grey squirrels had glucocorticoid concentrations that were three times higher than those in five sites without the invasive species. Moreover, in a longitudinal study, stress hormones in native red squirrels increased after colonisation by grey squirrels. When we experimentally reduced the abundance of the invasive grey squirrels, the concentration of faecal glucocorticoid metabolites in co-occurring red squirrels decreased significantly between pre- and postremoval periods. Hence, we found that the invasive species acts as a stressor which significantly increases the concentrations of glucocorticoids in the native species. Given that sustained elevations in glucocorticoids could reduce body growth and reproductive rate, our results are consistent with previous studies where the co-occurrence of the invasive grey squirrel was associated with smaller size and lower reproductive output in red squirrels.

A dynamic energy budget model to describe the reproduction and growth of invasive starfish Asterias amurensis in southeast Australia

The introduction of alien species is a global phenomenon that alters ecosystems structure and functioning. Invasive species are responsible for substantial economic and ecological losses. Invasive species impact resource availability, outcompeting and even causing extinction of native species. The management of invasive species requires knowledge on the ecology, physiology and population dynamics of these species. In a world where environmental conditions are changing fast due to global climate change and other anthropogenic stressors, a more comprehensive knowledge of the life history and physiology of these species is urgently needed. The DEB theory is unique in capturing the metabolic processes of an organism through its entire life cycle, and thus, is a useful tool to model lifetime feeding, growth, reproduction, and responses to changes in biotic and abiotic conditions. In this work, we estimated the parameters of a DEB model for Asterias amurensis. This starfish was introduced in Tasmania and is considered the most serious marine pest in Australia where it has caused local extinctions of several species. Asterias amurensis is a major predator and is a keystone species exerting top-down control of its prey populations by achieving large densities. We determined the influence of biotic and abiotic factors on the performance of A. amurensis. The DEB model presented here includes energy handling rules to describe gonad and pyloric caeca cycles. Model parameters were used to explore population dynamics of populations of A. amurensis in Australia. The DEB model allowed us to characterise the ecophysiology of A. amurensis, providing new insights on the role of food availability and temperature on its life cycle and reproduction strategy. Moreover it is a powerful tool for risk management of already established invasive populations and of regions with a high invasion risk.

Species introduction and taxonomic homogenization of Spanish freshwater fish fauna in relation to basin size, species richness and dam construction

The introduction of exotic species is a key global threat to biodiversity. Beyond an increased risk of native species extinction, there exists a loss of biodiversity distinctiveness. Nevertheless, quantitative information on biotic homogenization at the taxonomic level in relation to basin features is rare. We used freshwater fish distribution data in Spain at three different time periods (1952, 1995, and 2007) to assess the species introduction process and the temporal dynamics of taxonomic homogenization among river basins in relation to basin size, native species richness and dam construction variables. The degree of alteration of original faunas by species introduction has increased through time, especially in native richer species, which suggest that the number of non-native and native species covariate with environmental heterogeneity. On the other hand, neither basin size nor habitat modification by dam construction seems to explain the number of introduced species. Our results indicate that the taxonomic homogenization of Spanish fish fauna is a temporally and spatially dynamic process; initial local increases in β-diversity through species introduction could be blurred because of scaling to regional and national levels or by the continuous expansion of a reduced number of exotic species.

Ranking of invasive spread through urban green areas in the world’s 100 most populous cities

Urban landscapes are highly fragmented (leading to the extinction of native species) as well as transformed and disturbed (creating novel environments). Such conditions provide non-native species with opportunities to establish and spread through “urban green areas” (UGAs). UGAs can serve as stepping stones for many alien species to recruit and may become sources of propagules to launch invasions in adjoining natural ecosystems. There is great diversity in the spatial structures of UGAs worldwide; these are determined by the city’s level of development, human density, urban planning policy, and history. We explore the invasion risks of, and the potential of invasive spread in, UGAs in the world’s 100 most populous cities (in 40 countries). Based on maps of enhanced vegetation index at 250 m resolution over the extent of 25 by 25 km for each city centre, we simulate the invasion and spread of a reference species (a virtual ruderal invasive species) from the city centre into surrounding urban or rural areas. Doing so allowed us to provide an objective baseline for comparing urban susceptibility to such invasions across diverse cultures, histories and societies. We derive the global ranking of invasive spread potential for each city based on the rate of spread of the reference species, and the ranking of 40 countries, based on the average rate of spread in their cities. We explore correlates of spread rates after 100 time steps (years) by examining the roles of climate (mean annual temperature and rainfall), human demography (city population size and growth rate), and socio-economic indicators [human footprint, human development index and gross domestic product (GDP) per capita]. Small city population size and high GDP per capita are the only significant predictors of high potential for invasive spread. Among the G20 countries, Canada, South Korea, South Africa, France, USA and Brazil all feature in the top-10 countries, and Atlanta, Washington, D.C. and Dallas in the USA, Chittagong in Bangladesh, Toronto in Canada and Brasilia in Brazil are listed among the top 10 cities overall. Our results can serve as a global baseline assessment of invasive spread risks through UGAs, and call for improved protocols for monitoring, planning and management of UGAs.

Presumption of allelopathic compound(s) released in the leaf litter decomposition process of invasive plants: Calliandra calothyrsus and Cinchona pubescens

Mutaqien Z. 2017. Presumption of allelopathic compound(s) released in the leaf litter decomposition process of invasive plants: Calliandra calothyrsus and Cinchona pubescens. Pros Sem Nas Masy Biodiv Indon 3: 334-338. Invasive alien species is one of the main cause of ecological systems dramatically changes and also native species extinction worldwide. However, more studies are needed to discover its mechanism, including role of allelopathy compound in invasive plants competition. Cinchona pubescens Vahl. and Calliandra calothyrsus Meissn. are recorded as invasive species in some regions. Moreover, C. pubescens is stated as one of 100 of the world’s worst invasive alien species by IUCN. This study aimed to confirm indication of the existence of allelopathic mechanism in invasion process of these two invasive alien species by releasing allelopathic compound(s) from its leaves fall over decomposition process. To clarify this hypothesis, a preliminary study had been conducted by testing the effect of the compounds released from decomposition process over the times (7-180 days) to germination of Vigna radiata (L.) R. Wilczek in the laboratory. Completly Randomize Design was used by applying liquid produced by decomposition process of these two invasive species and control (three repetitions) to test its effects. Radicles and hypocotyls length were measured, compared and Anova analyzed by using R-statistic 3.1.3. Germination of V. radiata only significantly inhibited by compound(s) released by decomposition processes of C. callisaya’s leaves. Its inhibition effect was reduced over the times

A decade of insights into grassland ecosystem responses to global environmental change.

Earth's biodiversity and carbon uptake by plants, or primary productivity, are intricately interlinked, underlie many essential ecosystem processes, and depend on the interplay among environmental factors, many of which are being changed by human activities. While ecological theory generalizes across taxa and environments, most empirical tests of factors controlling diversity and productivity have been observational, single-site experiments, or meta-analyses, limiting our understanding of variation among site-level responses and tests of general mechanisms. A synthesis of results from ten years of a globally distributed, coordinated experiment, the Nutrient Network (NutNet), demonstrates that species diversity promotes ecosystem productivity and stability, and that nutrient supply and herbivory control diversity via changes in composition, including invasions of non-native species and extinction of native species. Distributed experimental networks are a powerful tool for tests and integration of multiple theories and for generating multivariate predictions about the effects of global changes on future ecosystems.

Control of invasive rats on islands and priorities for future action.

Invasive rats are one of the world's most successful animal groups that cause native species extinctions and ecosystem change, particularly on islands. On large islands, rat eradication is often impossible and population control, defined as the local limitation of rat abundance, is now routinely performed on many of the world's islands as an alternative management tool. However, a synthesis of the motivations, techniques, costs, and outcomes of such rat-control projects is lacking. We reviewed the literature, searched relevant websites, and conducted a survey via a questionnaire to synthesize the available information on rat-control projects in island natural areas worldwide to improve rat management and native species conservation. Data were collected from 136 projects conducted over the last 40 years; most were located in Australasia (46%) and the tropical Pacific (25%) in forest ecosystems (65%) and coastal strands (22%). Most of the projects targeted Rattus rattus and most (82%) were aimed at protecting birds and endangered ecosystems. Poisoning (35%) and a combination of trapping and poisoning (42%) were the most common methods. Poisoning allows for treatment of larger areas, and poison projects generally last longer than trapping projects. Second-generation anticoagulants (mainly brodifacoum and bromadiolone) were used most often. The median annual cost for rat-control projects was US$17,262 or US$227/ha. Median project duration was 4 years. For 58% of the projects, rat population reduction was reported, and 51% of projects showed evidence of positive effects on biodiversity. Our data were from few countries, revealing the need to expand rat-control distribution especially in some biodiversity hotspots. Improvement in control methods is needed as is regular monitoring to assess short- and long-term effectiveness of rat-control.

Can introduced species replace lost biodiversity? A test with freshwater molluscs

Human activity has dramatically accelerated both species extinctions and introductions, and the balance of these two processes is generally expected to reduce biodiversity and increase taxonomic homogenization. However, few tests of this hypothesis have been made. We tested whether new macroinvertebrate invaders in North American freshwaters can replace the recent loss of biodiversity, particularly focusing on molluscs. We found that both crustaceans and molluscs are overrepresented among endangered and recently extinct species, as well as among invaders. For molluscs, the number of recently extinct species (79 species) was more than twice that for exotic species (38 species). In addition, molluscan invaders are from different taxonomic families than recently extinct or endangered species. While most extinct and endangered molluscs are from streams and rivers, invaders preferentially colonize lakes and reservoirs. The impact of humans on species introductions and extinctions increases with spatial scale (from local to continental scales), resulting in the increased phylogenetic dissimilarity between introduced species and native communities. Construction of dams and alteration of the flow regimes of lotic systems will continue to lead to the extinction of native species, and promote the spread of invaders, resulting in a loss of biodiversity and taxonomic homogenization.

Overlooking the smallest matter: viruses impact biological invasions.

Parasites and pathogens have recently received considerable attention for their ability to affect biological invasions, however, researchers have largely overlooked the distinct role of viruses afforded by their unique ability to rapidly mutate and adapt to new hosts. With high mutation and genomic substitution rates, RNA and single-stranded DNA (ssDNA) viruses may be important constituents of invaded ecosystems, and could potentially behave quite differently from other pathogens. We review evidence suggesting that rapidly evolving viruses impact invasion dynamics in three key ways: (1) Rapidly evolving viruses may prevent exotic species from establishing self-sustaining populations. (2) Viruses can cause population collapses of exotic species in the introduced range. (3) Viruses can alter the consequences of biological invasions by causing population collapses and extinctions of native species. The ubiquity and frequent host shifting of viruses make their ability to influence invasion events likely. Eludicating the viral ecology of biological invasions will lead to an improved understanding of the causes and consequences of invasions, particularly as regards establishment success and changes to community structure that cannot be explained by direct interspecific interactions among native and exotic species.

Does Historical Coexistence with Dingoes Explain Current Avoidance of Domestic Dogs? Island Bandicoots Are Naïve to Dogs, unlike Their Mainland Counterparts.

Introduced predators have a global reputation for causing declines and extinctions of native species. Native prey naiveté towards novel predators is thought to be a key reason for predator impacts. However, naiveté is not necessarily forever: where coexistence establishes, it is likely that naiveté will be reduced through adaptation, and the once alien predator will eventually become recognised by prey. For example, native marsupial bandicoots in Sydney avoid backyards with domestic dogs (C. lupus familiaris), but not domestic cats (Felis catus), even though cats and dogs were both introduced about 200 years ago (Carthey and Banks 2012). The authors attributed bandicoots’ recognition of dogs to long-term exposure to a close relative of dogs, dingoes that arrived in Australia 4000 years ago. Here, we test a prediction of this hypothesis by taking the study to Tasmania, where dingoes have never been present but where domestic dogs also arrived about 200 years ago. We use a similar survey design to that of Carthey and Banks (2012): asking Hobart residents to report on pet-ownership, bandicoot sightings and scats within their backyards, as well as an array of yard characteristic control variables. We predicted that if long term experience with dingoes enabled mainland bandicoots to recognise domestic dogs, then Tasmanian bandicoots, which are inexperienced with dingoes, would not recognise domestic dogs. Our results indicate that Tasmanian bandicoots are naïve to both dogs and cats after only 200 years of coexistence, supporting our hypothesis and the notion that naiveté in native prey towards alien predators (as observed on the mainland) may eventually be overcome.

Persistence and survival of the spider Nephila plumipes in cities: do increased prey resources drive the success of an urban exploiter?

Species that successfully inhabit urban ecosystems are rare, and urbanisation often drives localised extinctions of native species. Nonetheless, some species take advantage of the novel conditions available in cities and increase in abundance. Trends in the abundance and distribution of species in urban areas have received much attention, but the precise elements of urban ecosystems that affect the survival of urban-dwelling species are largely unknown. Animals that successfully exploit urban environments may do so because of increases in the availability of resources or habitats. Here we assess the effects of anthropogenic landscapes and prey abundance on the persistence of an orb-weaving spider, Nephila plumipes. We assessed spider persistence for six months in situ along an urban gradient in Sydney. We then transplanted spiders from a common garden into sites along the gradient, monitored their persistence in the new environment and measured a suite of environmental variables at local and landscape scales. The abundance of prey was closely linked with spider persistence, in both the survey and the transplant experiment, and was positively associated with anthropogenic habitats. The surveyed spiders survived longer when located closer to the coast and transplanted spiders persisted longer in smaller sites with more impervious surfaces and reduced vegetation cover. Our study shows that urbanisation has a strong effect on potential prey abundance and can lead to increased persistence of N. plumipes, demonstrating the broad impacts that habitat disturbance can have on the life history and trophic interactions of city-dwelling animals.