Biological Invasions最新文献

Community resistance plays a crucial role in the successful invasion of alien plants. However, our understanding of how soil legacy effects of native species richness, parasitic plants, competition and soil microbes contribute to community resistance remain unclear. To compare the legacy effects of soil conditioning and the current effects of plant interactions, we performed an experiment in which Chromolaeana odorata (invader) growth was measured with or without competition on live and sterile soils with different conditioning histories (species richness). Overall, our research indicated that C. odorata outperformed two native species across treatments, however, this advantage was smaller on soils with species rich histories and with competition from current plant growth. Our findings also revealed that both the soil legacy effects of native richness and competition negatively impact the growth of C. odorata, and native plants tend to produce more biomass in soils with greater diversity and under competitive conditions (5.0%). Interestingly, the holoparasitic plant C. chinensis decreased native plant growth (− 40%) more than C. odorata growth (− 11%). Further, C. chinensis did not parasitize C. odorata on sterilized soil. Furthermore, C. odorata did not experience limitations from parasitism in sterilized soil, as indicated by a slight increase in biomass of 2.3%. These results indicated that soils with diverse plant histories, competition from native plants, and lower C. chinensis parasitism will synergistically decrease C. odorata invasion. This study underscores that community resistance to C. odorata is governed by an interplay of multiple biotic factors, both individually and in combination. Simultaneously, this study contributes to a theoretical foundation for understanding the successful invasion of alien plants.

The Argentine ant is one among the 100 worst invasive animal species of the world. It has invaded six continents, and poses significant threats to the native invertebrate fauna. Prior knowledge on the suitable ecological niches of Argentine ants may help to devise better management plans. This study delineates the niches of Argentine ants using the ecological niche modeling approach by maintaining the temporal match between the distributional information and environmental data. We used an exhaustive methodological framework to understand the niche characteristics of Argentine ants in their native and invaded ranges. The model developed using combined native and invaded range distributional information provided better habitat suitability predictions in the invaded ranges. Efforts were also made to identify the suitable niches of this invasive species globally. The current global model was projected onto two future periods (2041–2070 and 2071–2100) under two different emission scenarios (SSP126 and SSP585). Our study highlights four important features related to the ecological niches of Argentine ants: (1) large habitat preference towards permanent streams in the native ranges, (2) native ecological niche is only partly conserved across invaded ranges, (3) invaded range niches are largely differentiated, and (4) global warming induces an increase in habitat suitability in the northern hemisphere. The results of this study may provide potential insights for the effective implementation of management strategies.

When introduced species hybridize with native relatives, spread of advantageous invasive genes into native populations (introgression) is a conservation concern. Genome-scale SNP (single nucleotide polymorphism) analysis can be a powerful approach to detect hybridization and identify candidate loci experiencing selection in hybrid zones. However, followup studies are critical to verify and interpret potentially impactful patterns of introgression. In an earlier publication we identified three outlier loci (out of 68 unlinked SNPs) where non-native alleles appeared to have introgressed 90 km into the range of a threatened native salamander, while the other 65 markers showed no evidence of spread further than 12 km. This was consistent with strong selection favoring a few invasive traits, but our inferences necessarily depended on limited reference samples of the native species. Here, we further tested our initial interpretation by interrogating the outlier markers in greater detail. First, we isolated DNA from two museum specimens of native salamanders collected several decades before the introduction. Both had the putatively invasive SNPs, indicating that the SNP alleles were present before the introduction and therefore not diagnostic for nonnative ancestry. Second, we developed a novel genealogical analysis of DNA sequences (rather than SNPs) to infer allelic ancestry, since genealogical analysis of haplotypes minimizes the ancestry assignment errors that can occur with SNPs. When applied to the original loci, this analysis confirmed that the genotypes formerly interpreted as ‘superinvasive’ are native variants, and non-native alleles remain limited to areas near the original introduction sites.

The abundance of an invasive species within an ecosystem after introduction can depend on multiple factors. Although large-scale abiotic data are typically used to model the distribution of invasive species, there may be other fine-scale environmental or biotic factors within the invaded range influencing changes in the species’ distribution and abundance. Here, we examined the abundance of the invasive tropical/subtropical green porcelain crab, Petrolisthes armatus (Gibbes, 1850), at 33 oyster reef sites along 150 km of coastline within the northerly portion of its invaded range. We measured a suite of biological, physical, and landscape level metrics to examine which factors (other than temperature) were most associated with the abundance of this invasive species. P. armatus were present at 32 reefs across our spatial range and densities were highest at the northern sites in our domain. Our results revealed native mud crab density is positively correlated with P. armatus density, accounting for 23% of the spatial variation in abundance of P. armatus within its invaded range, more than 30 years after initial invasion. We hypothesize that the positive associations between native predatory mud crabs and this invasive crab may be a result of hydrodynamics aggregating both species within the same areas, or attraction by both crabs for the same fine-scale habitat structural attributes (i.e., interstitial space). These data emphasize the importance of collecting high-resolution survey data to understand the variables that are correlated with the abundance and distribution of invasive species at regional scales within its invaded range.

The spread of marine non-indigenous species (NIS) is driven largely by shipping and global trade. Biofouling on vessel hulls is a major source of invasions, but many biofouling organisms are sessile (non-motile) and require reproduction, which often produces mobile, waterborne propagules (e.g., larvae) that can colonize new regions. The ability of biofouling organisms to reproduce, however, can depend strongly on abiotic conditions at the time of reproduction but also potentially prior to any reproductive event. For many organisms, past environments can influence performance later in life via within-generation carryover effects, but how carryover effects influence potential NIS introductions is unclear. We conducted a laboratory experiment to explore within-generation carryover effects of salinity and how they operate across different environments in the barnacle Amphibalanus improvisus, a common biofouling organism. We exposed newly settled barnacles to two different salinities (15 and 28 psu) for three weeks, maintained them in a common salinity for five weeks, then re-exposed them to the two initial salinities in a fully-factorial design prior to measuring their reproductive output. We found that barnacles that switched salinities between the initial and final exposures tended to produce more nauplii larvae (up to 50%) than those that remained in the same salinity conditions, possibly because of a stress response induced by physiological acclimation to early life environments. Because adult biofouling species are likely to be exposed to variable environmental conditions during vessel transits, carryover effects and their impact on propagule output may be important to consider when evaluating potential NIS introductions via biofouling.

The golden twin-spot moth, Chrysodeixis chalcites Esper (Lepidoptera: Noctuidae), is a polyphagous, polyvoltine crop pest occurring natively from northern Europe to Mediterranean Africa and the Canary Islands. Larvae feed on a wide variety of naturally occurring plants as well as soybean and other legume crops, short staple cotton, tomato, potato, peppers, tobacco, and banana. Chrysodeixis chalcites has been recorded in agricultural lands in the Ontario peninsula in eastern Canada and in northern counties of Indiana, USA. Given the strong potential for C. chalcites to invade USA crop lands, it is important to identify environments most likely to sustain growing populations of this pest. Though C. chalcites is native to Europe and North Africa, it has invaded sub-Saharan Africa. Using occurrence data form the native and invaded ranges, and environmental predictors including bioclimatic conditions and human disturbance, we trained three ecological niche models to estimate an ensemble prediction of environmental suitability in the contiguous US. Because human impact is potentially a confounding predictor, models were trained both with and without it. High environmental suitability was projected for the Atlantic coast from New England to Florida, the Gulf coast, the lower Midwest, and the Pacific coast and Central Valley of California.

Solidago gigantea, a notorious invasive species in Europe and Asia, has been shown in previous studies to impact soil properties such as nutrient availability and pH. However, the strength and direction of these alterations have varied across studies. Additionally, the species reduces species richness in invaded communities, though the susceptibility of different plant communities to invasion remains unclear. To address these inconsistencies, we investigated invasion effects on soil properties and plant communities across various soil types, nitrogen and pH levels, and plant communities. Soil samples were collected from invaded and nearby uninvaded plots, with measurements taken for extractable nitrogen, pH, and moisture content. Plant species richness, diversity, Sorensen similarity, mean Ellenberg indicator values and some community mean plant traits were compared between invaded and uninvaded plots. Lastly, S. gigantea stand density and size in invaded plots were quantified. Solidago gigantea significantly altered soil extractable-N and pH, with the extent and direction of changes depending on initial soil conditions. Alterations were most pronounced in acid, N-poor soils. Species richness and diversity consistently decreased in invaded plots. However, this decline was not due to direct competition with native species but to the replacement of specialized, local plant communities with less diverse, fast growing generalist communities adapted to fertile habitats. Solidago gigantea acts as an invasive ecosystem engineer, modifying soil conditions after introduction. This not only facilitates its spread but also leads to lasting effects that can persist even after its removal. Further studies on other invasive species are needed to establish general patterns due to their varied effects on ecosystem properties.

An increase in the establishment and spread of invasive alien plant species (IAPS) poses significant socioeconomic and environmental impacts. This study aimed to detect potential variations in the density, biomass, and fruit and seed production of Argemone mexicana L. IAPS along with land uses and agroecologies in south Wollo, Ethiopia. Using a stratified sampling method, eight kebeles, which are Ethiopia’s small administrative divisions, were sampled. The data were collected from four land use types covering two agroecology. One-way ANOVA, Tukey’s HSD test, and an independent t-test were used to examine the differences between land use and agroecology respectively. The associations of density, biomass, fruit, and seed density with slope and elevation were assessed using simple linear regression, using R4.2.1 program software. The mean A. mexicana ha⁻¹ s’ varied, significantly from 19,000 to 82,416 and 35,079 to 47,062, the aboveground dry biomass in kg m⁻² was 0.032 to 1.59 and 0.1395 to 0.689, and the belowground dry biomass in kg m⁻² was 0.048 to 0.506 and 0.0988 to 0.2408 between land use and agroecology respectively. The mean fruit per A. mexicana varied from 19 to 97 and 35 to 56, and seed per fruit of A. mexicana was 330 to 400 and 351 to 378 between land use and agroecology, respectively. As the slope and elevation increased, the values of all the measured variables decreased. Grazing land and highland agroecology had the lowest mean values, whereas farmlands and agroecology in the midlands had the highest values. Intervention should began in farmland and midland agroecology to prevent A. mexicana invasion.

Invasive mammalian predators are a key threat to native fauna globally. Island ecosystems that developed in isolation from mammals are particularly threatened by introduced mammalian predators. This is the case in New Zealand, where introduced mammalian predators have caused the decline of native birds, lizards, and invertebrates. In alpine areas of New Zealand, predator control targets stoats, rats, and cats as they are recognised as the key threats to native birds. Mice, which are known predators of invertebrates at lower elevations, are not actively controlled. As a result, alpine invertebrates in New Zealand represent an ideal focus for a natural experiment to understand the effects of predator control efforts and invasive mice on native invertebrates that evolved in isolation from mammals. In the Fiordland region of New Zealand, we assessed the large-bodied alpine invertebrate community at eight different sites that vary in their occurrence of mice and control of higher-order predators. We found that the recent presence of mice influenced the invertebrate community: wētā (a group of native orthopterans) were less common at sites where mice were present, and the mean body size of invertebrates collected in pitfall traps was larger at sites where mice were absent compared to sites where they were present. Control of other predators (specifically rats and mustelids) did not influence invertebrate body size, abundance, or community composition. Our findings suggest that, as in lowland environments, mice are an important predator of large-bodied invertebrates in the alpine zone and should be incorporated into future predator management programmes.

Islands harbor a significant proportion of global biodiversity and also have disproportionately high richness of introduced species relative to continents. Given the sensitivity of island ecosystems to introduced species, data deficiencies on introduction pathways, patterns of establishment, and potential impacts of introduced species can hamper mitigation and conservation efforts on islands. The Caribbean region is emerging as a hotspot for introduced amphibian and reptile (herpetofaunal) species, but patterns associated with herpetofaunal introductions on specific islands are not well explored. Here, we perform a detailed investigation of Aruba, a small Caribbean island with an exceptionally high number of introduced herpetofaunal species. We compile a database from the literature of introduction pathways, introduction years, source locations, native ranges, establishment outcomes, habitat use, and ecological impacts for three newly documented species and the 12 previously documented introduced herpetofaunal species on Aruba. From this database we synthesize emergent introduction patterns on Aruba and highlight areas of data deficiency. Overall, the patterns on Aruba echo the patterns exhibited in the greater Caribbean region. Introduction rates on Aruba have been increasing exponentially, yet the introduction pathways and source locations of most species are unknown. Following introduction, most species successfully establish localized populations in anthropogenic habitat, but the ecological impacts of most species have not been well-assessed. We suggest increased monitoring of shipments will help identify potential pathways to slow the introduction of new species, and further studies of ecological impacts of introduced species are needed.