Moussab/ORKG-training-evaluation-set huggingface dataset:
Research field: Ecology and Evolutionary Biology
Title: Are invasive species the drivers or passengers of change in degraded ecosystems?
Abstract: Few invaded ecosystems are free from habitat loss and disturbance, leading to uncertainty whether dominant invasive species are driving community change or are passengers along for the environmental ride. The ''driver'' model predicts that invaded communities are highly interactive, with subordinate native species being limited or ex- cluded by competition from the exotic dominants. The ''passenger'' model predicts that invaded communities are primarily structured by noninteractive factors (environmental change, dispersal limitation) that are less constraining on the exotics, which thus dominate. We tested these alternative hypotheses in an invaded, fragmented, and fire-suppressed oak savanna. We examined the impact of two invasive dominant perennial grasses on community structure using a reduction (mowing of aboveground biomass) and removal (weeding of above- and belowground biomass) experiment conducted at different seasons and soil depths. We examined the relative importance of competition vs. dispersal limitation with experimental seed additions. Competition by the dominants limits the abundance and re- production of many native and exotic species based on their increased performance with removals and mowing. The treatments resulted in increased light availability and bare soil; soil moisture and N were unaffected. Although competition was limiting for some, 36 of 79 species did not respond to the treatments or declined in the absence of grass cover. Seed additions revealed that some subordinates are dispersal limited; competition alone was insufficient to explain their rarity even though it does exacerbate dispersal inefficiencies by lowering reproduction. While the net effects of the dominants were negative, their presence restricted woody plants, facilitated seedling survival with moderate disturbance (i.e., treatments applied in the fall), or was not the primary limiting factor for the occurrence of some species. Finally, the species most functionally distinct from the dominants (forbs, woody plants) responded most significantly to the treatments. This suggests that relative abundance is determined more by trade-offs relating to environmental conditions (long- term fire suppression) than to traits relating to resource capture (which should most impact functionally similar species). This points toward the passenger model as the underlying cause of exotic dominance, although their combined effects (suppressive and facilitative) on community structure are substantial.
Extracted statement — Measure of disturbance: reduction (mowing of aboveground biomass)
Research field: Ecology and Evolutionary Biology
Title: Architectural strategies of Rhamnus cathartica (Rhamnaceae) in relation to canopy openness
Abstract: While phenotypic plasticity is considered the major means that allows plant to cope with environmental heterogeneity, scant information is available on phenotypic plasticity of the whole-plant architecture in relation to ontogenic processes. We performed an architectural analysis to gain an understanding of the structural and ontogenic properties of common buckthorn (Rhamnus cathartica L., Rhamnaceae) growing in the understory and under an open canopy. We found that ontogenic effects on growth need to be calibrated if a full description of phenotypic plasticity is to be obtained. Our analysis pointed to three levels of organization (or nested structural units) in R. cathartica. Their modulation in relation to light conditions leads to the expression of two architectural strategies that involve sets of traits known to confer competitive advantage in their respective environments. In the understory, the plant develops a tree-like form. Its strategy here is based on restricting investment in exploitation str...
Extracted statement — Species name: Rhamnus cathartica L.
Research field: Ecology and Evolutionary Biology
Title: Leaf-level phenotypic variability and plasticity of invasive Rhododendron ponticum and non-invasive Ilex aquifolium co-occurring at two contrasting European sites
Abstract: To understand the role of leaf-level plasticity and variability in species invasiveness, foliar characteristics were studied in relation to seasonal average integrated quantum flux density (Qint) in the understorey evergreen species Rhododendron ponticum and Ilex aquifolium at two sites. A native relict population of R. ponticum was sampled in southern Spain (Mediterranean climate), while an invasive alien population was investigated in Belgium (temperate maritime climate). Ilex aquifolium was native at both sites. Both species exhibited a significant plastic response to Qint in leaf dry mass per unit area, thickness, photosynthetic potentials, and chlorophyll contents at the two sites. However, R. ponticum exhibited a higher photosynthetic nitrogen use efficiency and larger investment of nitrogen in chlorophyll than I. aquifolium. Since leaf nitrogen (N) contents per unit dry mass were lower in R. ponticum, this species formed a larger foliar area with equal photosynthetic potential and light-harvesting efficiency compared with I. aquifolium. The foliage of R. ponticum was mechanically more resistant with larger density in the Belgian site than in the Spanish site. Mean leaf-level phenotypic plasticity was larger in the Belgian population of R. ponticum than in the Spanish population of this species and the two populations of I. aquifolium. We suggest that large fractional investments of foliar N in photosynthetic function coupled with a relatively large mean, leaf-level phenotypic plasticity may provide the primary explanation for the invasive nature and superior performance of R. ponticum at the Belgian site. With alleviation of water limitations from Mediterranean to temperate maritime climates, the invasiveness of R. ponticum may also be enhanced by the increased foliage mechanical resistance observed in the alien populations.
Extracted statement — Species name: Rhododendron ponticum
Research field: Ecology and Evolutionary Biology
Title: Phenotypic divergence of exotic fish populations is shaped by spatial proximity and habitat differences across an invaded landscape
Abstract: Background: Brown trout (Salmo trutta) were introduced into, and subsequently colonized, a number of disparate watersheds on the island of Newfoundland, Canada (110,638 km 2 ), starting in 1883. Questions: Do environmental features of recently invaded habitats shape population-level phenotypic variability? Are patterns of phenotypic variability suggestive of parallel adaptive divergence? And does the extent of phenotypic divergence increase as a function of distance between populations? Hypotheses: Populations that display similar phenotypes will inhabit similar environments. Patterns in morphology, coloration, and growth in an invasive stream-dwelling fish should be consistent with adaptation, and populations closer to each other should be more similar than should populations that are farther apart. Organism and study system: Sixteen brown trout populations of probable common descent, inhabiting a gradient of environments. These populations include the most ancestral (∼130 years old) and most recently established (∼20 years old). Analytical methods: We used multivariate statistical techniques to quantify morphological (e.g. body shape via geometric morphometrics and linear measurements of traits), meristic (e.g. counts of pigmentation spots), and growth traits from 1677 individuals. To account for ontogenetic and allometric effects on morphology, we conducted separate analyses on three distinct size/age classes. We used the BIO-ENV routine and Mantel tests to measure the correlation between phenotypic and habitat features. Results: Phenotypic similarity was significantly correlated with environmental similarity, especially in the larger size classes of fish. The extent to which these associations between phenotype and habitat result from parallel evolution, adaptive phenotypic plasticity, or historical founder effects is not known. Observed patterns of body shape and fin sizes were generally consistent with predictions of adaptive trait patterns, but other traits showed less consistent patterns with habitat features. Phenotypic differences increased as a function of straight-line distance (km) between watersheds and to a lesser extent fish dispersal distances, which suggests habitat has played a more significant role in shaping population phenotypes compared with founder effects.
Extracted statement — Species name: Salmo trutta
Research field: Ecology and Evolutionary Biology
Title: Evolution of dispersal traits along an invasion route in the wind-dispersed Senecio inaequidens (Asteraceae) 
Abstract: In introduced organisms, dispersal propensity is expected to increase during range expansion. This prediction is based on the assumption that phenotypic plasticity is low compared to genetic diversity, and an increase in dispersal can be counteracted by the Allee effect. Empirical evidence in support of these hypotheses is however lacking. The present study tested for evidence of differentiation in dispersal-related traits and the Allee effect in the wind-dispersed invasive Senecio inaequidens (Asteraceae). We collected capitula from individuals in ten field populations, along an invasion route including the original introduction site in southern France. In addition, we conducted a common garden experiment from field-collected seeds and obtained capitula from individuals representing the same ten field populations. We analysed phenotypic variation in dispersal traits between field and common garden environments as a function of the distance between populations and the introduction site. Our results revealed low levels of phenotypic differentiation among populations. However, significant clinal variation in dispersal traits was demonstrated in common garden plants representing the invasion route. In field populations, similar trends in dispersal-related traits and evidence of an Allee effect were not detected. In part, our results supported expectations of increased dispersal capacity with range expansion, and emphasized the contribution of phenotypic plasticity under natural conditions.
Extracted statement — Species name: Senecio inaequidens
Research field: Ecology and Evolutionary Biology
Title: Increased fitness and plasticity of an invasive species in its introduced range: a study using Senecio pterophorus
Abstract: 1 When a plant species is introduced into a new range, it may differentiate genetically from the original populations in the home range. This genetic differentiation may influence the extent to which the invasion of the new range is successful. We tested this hypothesis by examining Senecio pterophorus, a South African shrub that was introduced into NE Spain about 40 years ago. We predicted that in the introduced range invasive populations would perform better and show greater plasticity than native populations. 2 Individuals of S. pterophorus from four Spanish (invasive) and four South African (native) populations were grown in Catalonia, Spain, in a common garden in which disturbance and water availability were manipulated. Fitness traits and several ecophysiological parameters were measured. 3 The invasive populations of S. pterophorus survived better throughout the summer drought in a disturbed (unvegetated) environment than native South African populations. This success may be attributable to the lower specific leaf area (SLA) and better water content regulation of the invasive populations in this treatment. 4 Invasive populations displayed up to three times higher relative growth rate than native populations under conditions of disturbance and non‐limiting water availability. 5 The reproductive performance of the invasive populations was higher in all treatments except under the most stressful conditions (i.e. in non‐watered undisturbed plots), where no plant from either population flowered. 6 The results for leaf parameters and chlorophyll fluorescence measurements suggested that the greater fitness of the invasive populations could be attributed to more favourable ecophysiological responses. 7 Synthesis. Spanish invasive populations of S. pterophorus performed better in the presence of high levels of disturbance, and displayed higher plasticity of fitness traits in response to resource availability than native South African populations. Our results suggest that genetic differentiation from source populations associated with founding may play a role in invasion success.
Extracted statement — Species name: Senecio pterophorus
Research field: Ecology and Evolutionary Biology
Title: Diversity and biomass of native macrophytes are negatively related to dominance of an invasive Poaceae in Brazilian sub-tropical streams
Abstract: Besides exacerbated exploitation, pollution, flow alteration and habitats degradation, freshwater biodiversity is also threatened by biological invasions. This paper addresses how native aquatic macrophyte communities are affected by the non-native species Urochloa arrecta, a current successful invader in Brazilian freshwater systems. We compared the native macrophytes colonizing patches dominated and non-dominated by this invader species. We surveyed eight streams in Northwest Parana State (Brazil). In each stream, we recorded native macrophytes' richness and biomass in sites where U. arrecta was dominant and in sites where it was not dominant or absent. No native species were found in seven, out of the eight investigated sites where U. arrecta was dominant. Thus, we found higher native species richness, Shannon index and native biomass values in sites without dominance of U. arrecta than in sites dominated by this invader. Although difficult to conclude about causes of such differences, we infer that the elevated biomass production by this grass might be the primary reason for alterations in invaded environments and for the consequent impacts on macrophytes' native communities. However, biotic resistance offered by native richer sites could be an alternative explanation for our results. To mitigate potential impacts and to prevent future environmental perturbations, we propose mechanical removal of the invasive species and maintenance or restoration of riparian vegetation, for freshwater ecosystems have vital importance for the maintenance of ecological services and biodiversity and should be preserved.
Extracted statement — Measure of native biodiversity: Shannon index
Research field: Ecology and Evolutionary Biology
Title: Shoreline development drives invasion of Phragmites australis and the loss of plant diversity on New England salt marshes
Abstract: Abstract: The reed Phragmites australis Cav. is aggressively invading salt marshes along the Atlantic Coast of North America. We examined the interactive role of habitat alteration (i.e., shoreline development) in driving this invasion and its consequences for plant richness in New England salt marshes. We surveyed 22 salt marshes in Narragansett Bay, Rhode Island, and quantified shoreline development, Phragmites cover, soil salinity, and nitrogen availability. Shoreline development, operationally defined as removal of the woody vegetation bordering marshes, explained >90% of intermarsh variation in Phragmites cover. Shoreline development was also significantly correlated with reduced soil salinities and increased nitrogen availability, suggesting that removing woody vegetation bordering marshes increases nitrogen availability and decreases soil salinities, thus facilitating Phragmites invasion. Soil salinity (64%) and nitrogen availability (56%) alone explained a large proportion of variation in Phragmites cover, but together they explained 80% of the variation in Phragmites invasion success. Both univariate and aggregate (multidimensional scaling) analyses of plant community composition revealed that Phragmites dominance in developed salt marshes resulted in an almost three‐fold decrease in plant species richness. Our findings illustrate the importance of maintaining integrity of habitat borders in conserving natural communities and provide an example of the critical role that local conservation can play in preserving these systems. In addition, our findings provide ecologists and natural resource managers with a mechanistic understanding of how human habitat alteration in one vegetation community can interact with species introductions in adjacent communities (i.e., flow‐on or adjacency effects) to hasten ecosystem degradation.
Extracted statement — Measure of disturbance: shoreline development
Research field: Ecology and Evolutionary Biology
Title: Variable effects of feral pig disturbances on native and exotic plants in a California grassland
Abstract: Biological invasions are a global phenomenon that can accelerate disturbance regimes and facilitate colonization by other nonnative species. In a coastal grassland in northern California, we conducted a four-year exclosure experiment to assess the effects of soil disturbances by feral pigs (Sus scrofa) on plant community composition and soil nitrogen availability. Our results indicate that pig disturbances had substantial effects on the community, although many responses varied with plant functional group, geographic origin (native vs. exotic), and grassland type. (''Short patches'' were dominated by annual grasses and forbs, whereas ''tall patches'' were dominated by perennial bunchgrasses.) Soil disturbances by pigs increased the richness of exotic plant species by 29% and native taxa by 24%. Although native perennial grasses were unaffected, disturbances reduced the bio- mass of exotic perennial grasses by 52% in tall patches and had no effect in short patches. Pig disturbances led to a 69% decrease in biomass of exotic annual grasses in tall patches but caused a 62% increase in short patches. Native, nongrass monocots exhibited the opposite biomass pattern as those seen for exotic annual grasses, with disturbance causing an 80% increase in tall patches and a 56% decrease in short patches. Native forbs were unaffected by disturbance, whereas the biomass of exotic forbs increased by 79% with disturbance in tall patches and showed no response in short patches. In contrast to these vegetation results, we found no evidence that pig disturbances affected nitrogen mineral- ization rates or soil moisture availability. Thus, we hypothesize that the observed vegetation changes were due to space clearing by pigs that provided greater opportunities for colo- nization and reduced intensity of competition, rather than changes in soil characteristics. In summary, although responses were variable, disturbances by feral pigs generally pro- moted the continued invasion of this coastal grassland by exotic plant taxa.
Extracted statement — Type of disturbance: Soil disturbance
Research field: Ecology and Evolutionary Biology
Title: Jack-of-all-trades: phenotypic plasticity facilitates the invasion of an alien slug species
Abstract: Invasive alien species might benefit from phenotypic plasticity by being able to (i) maintain fitness in stressful environments (‘robust’), (ii) increase fitness in favourable environments (‘opportunistic’), or (iii) combine both abilities (‘robust and opportunistic’). Here, we applied this framework, for the first time, to an animal, the invasive slug, Arion lusitanicus, and tested (i) whether it has a more adaptive phenotypic plasticity compared with a congeneric native slug, Arion fuscus, and (ii) whether it is robust, opportunistic or both. During one year, we exposed specimens of both species to a range of temperatures along an altitudinal gradient (700–2400 m a.s.l.) and to high and low food levels, and we compared the responsiveness of two fitness traits: survival and egg production. During summer, the invasive species had a more adaptive phenotypic plasticity, and at high temperatures and low food levels, it survived better and produced more eggs than A. fuscus, representing the robust phenotype. During winter, A. lusitanicus displayed a less adaptive phenotype than A. fuscus. We show that the framework developed for plants is also very useful for a better mechanistic understanding of animal invasions. Warmer summers and milder winters might lead to an expansion of this invasive species to higher altitudes and enhance its spread in the lowlands, supporting the concern that global climate change will increase biological invasions.
Extracted statement — Specific traits: Survival and egg production
Research field: Ecology and Evolutionary Biology
Title: Latitudinal Patterns in Phenotypic Plasticity and Fitness-Related Traits: Assessing the Climatic Variability Hypothesis (CVH) with an Invasive Plant Species
Abstract: Phenotypic plasticity has been suggested as the main mechanism for species persistence under a global change scenario, and also as one of the main mechanisms that alien species use to tolerate and invade broad geographic areas. However, contrasting with this central role of phenotypic plasticity, standard models aimed to predict the effect of climatic change on species distributions do not allow for the inclusion of differences in plastic responses among populations. In this context, the climatic variability hypothesis (CVH), which states that higher thermal variability at higher latitudes should determine an increase in phenotypic plasticity with latitude, could be considered a timely and promising hypothesis. Accordingly, in this study we evaluated, for the first time in a plant species (Taraxacum officinale), the prediction of the CVH. Specifically, we measured plastic responses at different environmental temperatures (5 and 20°C), in several ecophysiological and fitness-related traits for five populations distributed along a broad latitudinal gradient. Overall, phenotypic plasticity increased with latitude for all six traits analyzed, and mean trait values increased with latitude at both experimental temperatures, the change was noticeably greater at 20° than at 5°C. Our results suggest that the positive relationship found between phenotypic plasticity and geographic latitude could have very deep implications on future species persistence and invasion processes under a scenario of climate change.
Extracted statement — Species name: Taraxacum officinale
Research field: Ecology and Evolutionary Biology
Title: Functional differences in response to drought in the invasive Taraxacum officinale from native and introduced alpine habitat ranges
Abstract: Background: Phenotypic plasticity and ecotypic differentiation have been suggested as the main mechanisms by which widely distributed species can colonise broad geographic areas with variable and stressful conditions. Some invasive plant species are among the most widely distributed plants worldwide. Plasticity and local adaptation could be the mechanisms for colonising new areas. Aims: We addressed if Taraxacum officinale from native (Alps) and introduced (Andes) stock responded similarly to drought treatment, in terms of photosynthesis, foliar angle, and flowering time. We also evaluated if ontogeny affected fitness and physiological responses to drought. Methods: We carried out two common garden experiments with both seedlings and adults (F2) of T. officinale from its native and introduced ranges in order to evaluate their plasticity and ecotypic differentiation under a drought treatment. Results: Our data suggest that the functional response of T. officinale individuals from the introduced range to drought is the result of local adaptation rather than plasticity. In addition, the individuals from the native distribution range were more sensitive to drought than those from the introduced distribution ranges at both seedling and adult stages. Conclusions: These results suggest that local adaptation may be a possible mechanism underlying the successful invasion of T. officinale in high mountain environments of the Andes.
Extracted statement — Species name: Taraxacum officinale