Moussab/ORKG-training-evaluation-set huggingface dataset:
Research field: Ecology and Evolutionary Biology
Title: Facilitation and competition among invasive plants: A field experiment with alligatorweed and water hyacinth
Abstract: Ecosystems that are heavily invaded by an exotic species often contain abundant populations of other invasive species. This may reflect shared responses to a common factor, but may also reflect positive interactions among these exotic species. Armand Bayou (Pasadena, TX) is one such ecosystem where multiple species of invasive aquatic plants are common. We used this system to investigate whether presence of one exotic species made subsequent invasions by other exotic species more likely, less likely, or if it had no effect. We performed an experiment in which we selectively removed exotic rooted and/or floating aquatic plant species and tracked subsequent colonization and growth of native and invasive species. This allowed us to quantify how presence or absence of one plant functional group influenced the likelihood of successful invasion by members of the other functional group. We found that presence of alligatorweed (rooted plant) decreased establishment of new water hyacinth (free-floating plant) patches but increased growth of hyacinth in established patches, with an overall net positive effect on success of water hyacinth. Water hyacinth presence had no effect on establishment of alligatorweed but decreased growth of existing alligatorweed patches, with an overall net negative effect on success of alligatorweed. Moreover, observational data showed positive correlations between hyacinth and alligatorweed with hyacinth, on average, more abundant. The negative effect of hyacinth on alligatorweed growth implies competition, not strong mutual facilitation (invasional meltdown), is occurring in this system. Removal of hyacinth may increase alligatorweed invasion through release from competition. However, removal of alligatorweed may have more complex effects on hyacinth patch dynamics because there were strong opposing effects on establishment versus growth. The mix of positive and negative interactions between floating and rooted aquatic plants may influence local population dynamics of each group and thus overall invasion pressure in this watershed.
Extracted statement — hypothesis: Invasional meltdown
Research field: Ecology and Evolutionary Biology
Title: Reciprocally beneficial interactions between introduced plants and ants are induced by the presence of a third introduced species
Abstract: Interspecific interactions play an important role in the success of introduced species. For example, the ‘enemy release’ hypothesis posits that introduced species become invasive because they escape top–down regulation by natural enemies while the ‘invasional meltdown’ hypothesis posits that invasions may be facilitated by synergistic interactions between introduced species. Here, we explore how facilitation and enemy release interact to moderate the potential effect of a large category of positive interactions – protection mutualisms. We use the interactions between an introduced plant (Japanese knotweed Fallopia japonica), an introduced herbivore (Japanese beetle Popillia japonica), an introduced ant (European red ant Myrmica rubra), and native ants and herbivores in riparian zones of the northeastern United States as a model system. Japanese knotweed produces sugary extrafloral nectar that is attractive to ants, and we show that both sugar reward production and ant attendance increase when plants experience a level of leaf damage that is typical in the plants’ native range. Using manipulative experiments at six sites, we demonstrate low levels of ant patrolling, little effect of ants on herbivory rates, and low herbivore pressure during midsummer. Herbivory rates and the capacity of ants to protect plants (as evidenced by effects of ant exclusion) increased significantly when plants were exposed to introduced Japanese beetles that attack plants in the late summer. Beetles were also associated with greater on-plant foraging by ants, and among-plant differences in ant-foraging were correlated with the magnitude of damage inflicted on plants by the beetles. Last, we found that sites occupied by introduced M. rubra ants almost invariably included Japanese knotweed. Thus, underlying variation in the spatiotemporal distribution of the introduced herbivore influences the provision of benefits to the introduced plant and to the introduced ant. More specifically, the presence of the introduced herbivore converts an otherwise weak interaction between two introduced species into a reciprocally beneficial mutualism. Because the prospects for facilitation are linked to the prospects for enemy release in protection mutualisms, species
Extracted statement — hypothesis: Invasional meltdown
Research field: Ecology and Evolutionary Biology
Title: Novel interactions between non-native mammals and fungi facilitate establishment of invasive pines
Abstract: The role of novel ecological interactions between mammals, fungi and plants in invaded ecosystems remains unresolved, but may play a key role in the widespread successful invasion of pines and their ectomycorrhizal fungal associates, even where mammal faunas originate from different continents to trees and fungi as in New Zealand. We examine the role of novel mammal associations in dispersal of ectomycorrhizal fungal inoculum of North American pines (Pinus contorta, Pseudotsuga menziesii), and native beech trees (Lophozonia menziesii) using faecal analyses, video monitoring and a bioassay experiment. Both European red deer (Cervus elaphus) and Australian brushtail possum (Trichosurus vulpecula) pellets contained spores and DNA from a range of native and non‐native ectomycorrhizal fungi. Faecal pellets from both animals resulted in ectomycorrhizal infection of pine seedlings with fungal genera Rhizopogon and Suillus, but not with native fungi or the invasive fungus Amanita muscaria, despite video and DNA evidence of consumption of these fungi. Native L. menziesii seedlings never developed any ectomycorrhizal infection from faecal pellet inoculation. Synthesis. Our results show that introduced mammals from Australia and Europe facilitate the co‐invasion of invasive North American trees and Northern Hemisphere fungi in New Zealand, while we find no evidence that introduced mammals benefit native trees or fungi. This novel tripartite ‘invasional meltdown’, comprising taxa from three kingdoms and three continents, highlights unforeseen consequences of global biotic homogenization.
Extracted statement — hypothesis: Invasional meltdown
Research field: Ecology and Evolutionary Biology
Title: Experimental test of the invasional meltdown hypothesis: na exotic herbivore facilitates na exotic plant, but the plant does not reciprocally facilitate the herbivore
Abstract: Summary Ecosystems with multiple exotic species may be affected by facilitative invader interactions, which could lead to additional invasions (invasional meltdown hypothesis). Experiments show that one-way facilitation favours exotic species and observational studies suggest that reciprocal facilitation among exotic species may lead to an invasional meltdown. We conducted a mesocosm experiment to determine whether reciprocal facilitation occurs in wetland communities. We established communities with native wetland plants and aquatic snails. Communities were assigned to treatments: control (only natives), exotic snail (Pomacea maculata) invasion, exotic plant (Alternanthera philoxeroides) invasion, sequential invasion (snails then plants or plants then snails) or simultaneous invasion (snails and plants). Pomacea maculata preferentially consumed native plants, so A. philoxeroides comprised a larger percentage of plant mass and native plant mass was lowest in sequential (snail then plant) invasion treatments. Even though P. maculata may indirectly facilitate A. philoxeroides, A. philoxeroides did not reciprocally facilitate P. maculata. Rather, ecosystems invaded by multiple exotic species may be affected by one-way facilitation or reflect exotic species’ common responses to abiotic factors or common paths of introduction.
Extracted statement — hypothesis: Invasional meltdown
Research field: Ecology and Evolutionary Biology
Title: Biodiversity ffects and rates of spred of nonnative eucalypt woodlands in central California
Abstract: Woodlands comprised of planted, nonnative trees are increasing in extent globally, while native woodlands continue to decline due to human activities. The ecological impacts of planted woodlands may include changes to the communities of understory plants and animals found among these nonnative trees relative to native woodlands, as well as invasion of adjacent habitat areas through spread beyond the originally planted areas. Eucalypts (Eucalyptus spp.) are among the most widely planted trees worldwide, and are very common in California, USA. The goals of our investigation were to compare the biological communities of nonnative eucalypt woodlands to native oak woodlands in coastal central California, and to examine whether planted eucalypt groves have increased in size over the past decades. We assessed site and habitat attributes and characterized biological communities using understory plant, ground-dwelling arthropod, amphibian, and bird communities as indicators. Degree of difference between native and nonnative woodlands depended on the indicator used. Eucalypts had significantly greater canopy height and cover, and significantly lower cover by perennial plants and species richness of arthropods than oaks. Community composition of arthropods also differed significantly between eucalypts and oaks. Eucalypts had marginally significantly deeper litter depth, lower abundance of native plants with ranges limited to western North America, and lower abundance of amphibians. In contrast to these differences, eucalypt and oak groves had very similar bird community composition, species richness, and abundance. We found no evidence of "invasional meltdown," documenting similar abundance and richness of nonnatives in eucalypt vs. oak woodlands. Our time-series analysis revealed that planted eucalypt groves increased 271% in size, on average, over six decades, invading adjacent areas. Our results inform science-based management of California woodlands, revealing that while bird communities would probably not be affected by restoration of eucalypt to oak woodlands, such a restoration project would not only stop the spread of eucalypts into adjacent habitats but would also enhance cover by western North American native plants and perennials, enhance amphibian abundance, and increase arthropod richness.
Extracted statement — hypothesis: Invasional meltdown
Research field: Ecology and Evolutionary Biology
Title: Quantifying "apparent" impact and distinguishing impact from invasiveness in multispecies plant invasions
Abstract: The quantification of invader impacts remains a major hurdle to understanding and managing invasions. Here, we demonstrate a method for quantifying the community-level impact of multiple plant invaders by applying Parker et al.'s (1999) equation (impact = range x local abundance x per capita effect or per unit effect) using data from 620 survey plots from 31 grasslands across west-central Montana, USA. In testing for interactive effects of multiple invaders on native plant abundance (percent cover), we found no evidence for invasional meltdown or synergistic interactions for the 25 exotics tested. While much concern exists regarding impact thresholds, we also found little evidence for nonlinear relationships between invader abundance and impacts. These results suggest that management actions that reduce invader abundance should reduce invader impacts monotonically in this system. Eleven of 25 invaders had significant per unit impacts (negative local-scale relationships between invader and native cover). In decomposing the components of impact, we found that local invader abundance had a significant influence on the likelihood of impact, but range (number of plots occupied) did not. This analysis helped to differentiate measures of invasiveness (local abundance and range) from impact to distinguish high-impact invaders from invaders that exhibit negligible impacts, even when widespread. Distinguishing between high- and low-impact invaders should help refine trait-based prediction of problem species. Despite the unique information derived from evaluation of per unit effects of invaders, invasiveness 'scores based on range and local abundance produced similar rankings to impact scores that incorporated estimates of per unit effects. Hence, information on range and local abundance alone was sufficient to identify problematic plant invaders at the regional scale. In comparing empirical data on invader impacts to the state noxious weed list, we found that the noxious weed list captured 45% of the high impact invaders but missed 55% and assigned the lowest risk category to the highest-impact invader. While such subjective weed lists help to guide invasive species management, empirical data are needed to develop more comprehensive rankings of ecological impacts. Using weed lists to classify invaders for testing invasion theory is not well supported.
Extracted statement — hypothesis: Invasional meltdown
Research field: Ecology and Evolutionary Biology
Title: Strong invaders are strong defenders - implications for the resistance of invaded communities
Abstract: Many ecosystems receive a steady stream of non-native species. How biotic resistance develops over time in these ecosystems will depend on how established invaders contribute to subsequent resistance. If invasion success and defence capacity (i.e. contribution to resistance) are correlated, then community resistance should increase as species accumulate. If successful invaders also cause most impact (through replacing native species with low defence capacity) then the effect will be even stronger. If successful invaders instead have weak defence capacity or even facilitative attributes, then resistance should decrease with time, as proposed by the invasional meltdown hypothesis. We analysed 1157 introductions of freshwater fish in Swedish lakes and found that species' invasion success was positively correlated with their defence capacity and impact, suggesting that these communities will develop stronger resistance over time. These insights can be used to identify scenarios where invading species are expected to cause large impact.
Extracted statement — hypothesis: Invasional meltdown
Research field: Ecology and Evolutionary Biology
Title: Early life stages of exotic gobiids as new hosts for unionid glochidia
Abstract: Summary Introduction of an exotic species has the potential to alter interactions between fish and bivalves; yet our knowledge in this field is limited, not least by lack of studies involving fish early life stages (ELS). Here, for the first time, we examine glochidial infection of fish ELS by native and exotic bivalves in a system recently colonised by two exotic gobiid species (round goby Neogobius melanostomus, tubenose goby Proterorhinus semilunaris) and the exotic Chinese pond mussel Anodonta woodiana. The ELS of native fish were only rarely infected by native glochidia. By contrast, exotic fish displayed significantly higher native glochidia prevalence and mean intensity of infection than native fish (17 versus 2% and 3.3 versus 1.4 respectively), inferring potential for a parasite spillback/dilution effect. Exotic fish also displayed a higher parasitic load for exotic glochidia, inferring potential for invasional meltdown. Compared to native fish, presence of gobiids increased the total number of glochidia transported downstream on drifting fish by approximately 900%. We show that gobiid ELS are a novel, numerous and ‘attractive’ resource for unionid glochidia. As such, unionids could negatively affect gobiid recruitment through infection-related mortality of gobiid ELS and/or reinforce downstream unionid populations through transport on drifting gobiid ELS. These implications go beyond what is suggested in studies of older life stages, thereby stressing the importance of an holistic ontogenetic approach in ecological studies.
Extracted statement — hypothesis: Invasional meltdown
Research field: Ecology and Evolutionary Biology
Title: Morphological variation between non-native lake- and stream-dwelling pumpkinseed Lepomis gibbosusin the Iberian Peninsula
Abstract: The objective of this study was to test if morphological differences in pumpkinseed Lepomis gibbosus found in their native range (eastern North America) that are linked to feeding regime, competition with other species, hydrodynamic forces and habitat were also found among stream- and lake- or reservoir-dwelling fish in Iberian systems. The species has been introduced into these systems, expanding its range, and is presumably well adapted to freshwater Iberian Peninsula ecosystems. The results show a consistent pattern for size of lateral fins, with L. gibbosus that inhabit streams in the Iberian Peninsula having longer lateral fins than those inhabiting reservoirs or lakes. Differences in fin placement, body depth and caudal peduncle dimensions do not differentiate populations of L. gibbosus from lentic and lotic water bodies and, therefore, are not consistent with functional expectations. Lepomis gibbosus from lotic and lentic habitats also do not show a consistent pattern of internal morphological differentiation, probably due to the lack of lotic-lentic differences in prey type. Overall, the univariate and multivariate analyses show that most of the external and internal morphological characters that vary among populations do not differentiate lotic from lentic Iberian populations. The lack of expected differences may be a consequence of the high seasonal flow variation in Mediterranean streams, and the resultant low- or no-flow conditions during periods of summer drought.
Extracted statement — Species name: Lepomis gibbosus
Research field: Ecology and Evolutionary Biology
Title: Patterns of trait convergence and divergence among native and exotic species in herbaceous plant communities are not modified by nitrogen enrichment
Abstract: 1. Community assembly theories predict that the success of invading species into a new community should be predictable by functional traits. Environmental filters could constrain the number of successful ecological strategies in a habitat, resulting in similar suites of traits between native and successfully invading species (convergence). Conversely, concepts of limiting similarity and competitive exclusion predict native species will prevent invasion by functionally similar exotic species, resulting in trait divergence between the two species pools. Nutrient availability may further alter the strength of convergent or divergent forces in community assembly, by relaxing environmental constraints and/or influencing competitive interactions.
Extracted statement — hypothesis: limiting similarity
Research field: Ecology and Evolutionary Biology
Title: Limiting similarity between invaders and dominant species in herbaceous plant communities?
Abstract: 1 Limiting similarity theory predicts that successful invaders should differ functionally from species already present in the community. This theory has been tested by manipulating the functional richness of communities, but not other aspects of functional diversity such as the identity of dominant species. Because dominant species are known to have strong effects on ecosystem functioning, I hypothesized that successful invaders should be functionally dissimilar from community dominants. 2 To test this hypothesis, I added seeds of 17 different species to two different experiments: one in a natural oldfield community that had patches dominated by different plant species, and one in grassland mesocosms that varied in the identity of the dominant species but not in species richness or evenness. I used indicator species analyses to test whether invaders had higher establishment success in plots with functionally different dominant species. 3 A large percentage of invader species (47–71%) in both experiments showed no difference in affinity across the different dominant treatments, although one‐third of species did show some evidence for limiting similarity. Exotic invaders had much higher invasion success than native invaders, and seemed to be inhibited by dominant species that were functionally similar. However, even these invasion patterns were not consistent across the two experiments. 4 The results from this study show that there is some evidence that dominant species suppress invasion by functionally similar species, beyond the effect of simple presence or absence of species in communities, although it is not the sole factor affecting invasion success. Patterns of invasion success were inconsistent across species and experiments, indicating that other studies using only a single species of invader to make conclusions about community invasibility should be interpreted with caution.
Extracted statement — hypothesis: limiting similarity
Research field: Ecology and Evolutionary Biology
Title: Assembly rules operating along a primary riverbed-grassland successional sequence
Abstract: 1 Assembly rules are broadly defined as any filter imposed on a regional species pool that acts to determine the local community structure and composition. Environmental filtering is thought to result in the formation of groups of species with similar traits that tend to co‐occur more often than expected by chance alone, known as Beta guilds. At a smaller scale, within a single Beta guild, species may be partitioned into Alpha guilds – groups of species that have similar resource use and hence should tend not to co‐occur at small scales due the principle of limiting similarity. 2 This research investigates the effects of successional age and the presence of an invasive exotic species on Alpha and Beta guild structuring within plant communities along two successional river terrace sequences in the Waimakariri braided river system in New Zealand. 3 Fifteen sites were sampled, six with and nine without the Russel lupin (Lupinus polyphyllus), an invasive exotic species. At each site, species presence/absence was recorded in 100 circular quadrats (5 cm in diameter) at 30‐cm intervals along a 30‐m transect. Guild proportionality (Alpha guild structuring) was tested for using two a priori guild classifications each containing three guilds, and cluster analysis was used to test for environmental structuring between sites. 4 Significant assembly rules based on Alpha guild structuring were found, particularly for the monocot and dicot guild. Guild proportionality increased with increasing ecological age, which indicated an increase in the relative importance of competitive structuring at later stages of succession. This provides empirical support for Weiher and Keddy's theoretical model of community assembly. 5 Lupins were associated with altered Alpha and Beta guild structuring at early mid successional sites. Lupin‐containing sites had higher silt content than sites without lupins, and this could have altered the strength and scale of competitive structuring within the communities present. 6 This research adds to the increasing evidence for the existence of assembly rules based on limiting similarity within plant communities, and demonstrates the need to incorporate gradients of environmental and competitive adversity when investigating the rules that govern community assembly.
Extracted statement — hypothesis: limiting similarity