Moussab/ORKG-training-evaluation-set huggingface dataset:
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 — Habitat: Freshwater
Research field: Ecology and Evolutionary Biology
Title: Native and introduced fish species richness in Chilean Patagonian lakes: inferences on invasion mechanisms using salmonid-free lakes
Abstract: Geographic patterns of species richness have been linked to many physical and biological drivers. In this study, we document and explain gradients of species richness for native and introduced freshwater fish in Chilean lakes. We focus on the role of the physical environment to explain native richness patterns. For patterns of introduced salmonid richness and dominance, we also examine the biotic resistance and human activity hypotheses. We were particularly interested in identifying the factors that best explain the persistence of salmonid‐free lakes in Patagonia.
Extracted statement — Habitat: Freshwater
Research field: Ecology and Evolutionary Biology
Title: Fish invasions in the world's river systems: When natural processes are blurred by human activities
Abstract: Because species invasions are a principal driver of the human-induced biodiversity crisis, the identification of the major determinants of global invasions is a prerequisite for adopting sound conservation policies. Three major hypotheses, which are not necessarily mutually exclusive, have been proposed to explain the establishment of non-native species: the “human activity” hypothesis, which argues that human activities facilitate the establishment of non-native species by disturbing natural landscapes and by increasing propagule pressure; the “biotic resistance” hypothesis, predicting that species-rich communities will readily impede the establishment of non-native species; and the “biotic acceptance” hypothesis, predicting that environmentally suitable habitats for native species are also suitable for non-native species. We tested these hypotheses and report here a global map of fish invasions (i.e., the number of non-native fish species established per river basin) using an original worldwide dataset of freshwater fish occurrences, environmental variables, and human activity indicators for 1,055 river basins covering more than 80% of Earth's surface. First, we identified six major invasion hotspots where non-native species represent more than a quarter of the total number of species. According to the World Conservation Union, these areas are also characterised by the highest proportion of threatened fish species. Second, we show that the human activity indicators account for most of the global variation in non-native species richness, which is highly consistent with the “human activity” hypothesis. In contrast, our results do not provide support for either the “biotic acceptance” or the “biotic resistance” hypothesis. We show that the biogeography of fish invasions matches the geography of human impact at the global scale, which means that natural processes are blurred by human activities in driving fish invasions in the world's river systems. In view of our findings, we fear massive invasions in developing countries with a growing economy as already experienced in developed countries. Anticipating such potential biodiversity threats should therefore be a priority.
Extracted statement — Habitat: Freshwater
Research field: Ecology and Evolutionary Biology
Title: Cryptic seedling herbivory by nocturnal introduced generalists impacts survival, performance of native and exotic plants
Abstract: Although much of the theory on the success of invasive species has been geared at escape from specialist enemies, the impact of introduced generalist invertebrate herbivores on both native and introduced plant species has been underappreciated. The role of nocturnal invertebrate herbivores in structuring plant communities has been examined extensively in Europe, but less so in North America. Many nocturnal generalists (slugs, snails, and earwigs) have been introduced to North America, and 96% of herbivores found during a night census at our California Central Valley site were introduced generalists. We explored the role of these herbivores in the distribution, survivorship, and growth of 12 native and introduced plant species from six families. We predicted that introduced species sharing an evolutionary history with these generalists might be less vulnerable than native plant species. We quantified plant and herbivore abundances within our heterogeneous site and also established herbivore removal experiments in 160 plots spanning the gamut of microhabitats. As 18 collaborators, we checked 2000 seedling sites every day for three weeks to assess nocturnal seedling predation. Laboratory feeding trials allowed us to quantify the palatability of plant species to the two dominant nocturnal herbivores at the site (slugs and earwigs) and allowed us to account for herbivore microhabitat preferences when analyzing attack rates on seedlings. The relationship between local slug abundance and percent cover of five common plant taxa at the field site was significantly negatively associated with the mean palatability of these taxa to slugs in laboratory trials. Moreover, seedling mortality of 12 species in open-field plots was positively correlated with mean palatability of these taxa to both slugs and earwigs in laboratory trials. Counter to expectations, seedlings of native species were neither more vulnerable nor more palatable to nocturnal generalists than those of introduced species. Growth comparison of plants within and outside herbivore exclosures also revealed no differences between native and introduced plant species, despite large impacts of herbivores on growth. Cryptic nocturnal predation on seedlings was common and had large effects on plant establishment at our site. Without intensive monitoring, such predation could easily be misconstrued as poor seedling emergence.
Extracted statement — Release of which kind of enemies?: Generalists
Research field: Ecology and Evolutionary Biology
Title: Adaptation vs. phenotypic plasticity in the success of a clonal invader
Abstract: The relative importance of plasticity vs. adaptation for the spread of invasive species has rarely been studied. We examined this question in a clonal population of invasive freshwater snails (Potamopyrgus antipodarum) from the western United States by testing whether observed plasticity in life history traits conferred higher fitness across a range of temperatures. We raised isofemale lines from three populations from different climate regimes (high- and low-elevation rivers and an estuary) in a split-brood, common-garden design in three temperatures. We measured life history and growth traits and calculated population growth rate (as a measure of fitness) using an age-structured projection matrix model. We found a strong effect of temperature on all traits, but no evidence for divergence in the average level of traits among populations. Levels of genetic variation and significant reaction norm divergence for life history traits suggested some role for adaptation. Plasticity varied among traits and was lowest for size and reproductive traits compared to age-related traits and fitness. Plasticity in fitness was intermediate, suggesting that invasive populations are not general-purpose genotypes with respect to the range of temperatures studied. Thus, by considering plasticity in fitness and its component traits, we have shown that trait plasticity alone does not yield the same fitness across a relevant set of temperature conditions.
Extracted statement — Specific traits: Growth
Research field: Ecology and Evolutionary Biology
Title: Feeding behaviour, predatory functional response and trophic interactions of the invasive Chinese mitten crab (Eriocheir sinensis) and signal crayfish (Pacifastacus leniusculus)
Abstract: 1. Freshwaters are subject to particularly high rates of species introductions; hence, invaders increasingly co-occur and may interact to enhance impacts on ecosystem structure and function. As trophic interactions are a key mechanism by which invaders influence communities, we used a combination of approaches to investigate the feeding preferences and community impacts of two globally invasive large benthic decapods that co-occur in freshwaters: the signal crayfish (Pacifastacus leniusculus) and Chinese mitten crab (Eriocheir sinensis). 2. In laboratory preference tests, both consumed similar food items, including chironomids, isopods and the eggs of two coarse fish species. In a comparison of predatory functional responses with a native crayfish Austropotamobius pallipes), juvenile E. sinensis had a greater predatory intensity than the native A. pallipes on the keystone shredder Gammarus pulex, and also displayed a greater preference than P. leniusculus for this prey item. 3. In outdoor mesocosms (n = 16) used to investigate community impacts, the abundance of amphipods, isopods, chironomids and gastropods declined in the presence of decapods, and a decapod >gastropod >periphyton trophic cascade was detected when both species were present. Eriocheir sinensis affected a wider range of animal taxa than P. leniusculus. 4. Stable-isotope and gut-content analysis of wild-caught adult specimens of both invaders revealed a wide and overlapping range of diet items including macrophytes, algae, terrestrial detritus, macroinvertebrates and fish. Both decapods were similarly enriched in 15N and occupied the same trophic level as Ephemeroptera, Odonata and Notonecta. Eriocheir sinensis d13C values were closely aligned with macrophytes indicating a reliance on energy from this basal resource, supported by evidence of direct consumption from gut contents. Pacifastacus leniusculus d13C values were intermediate between those of terrestrial leaf litter and macrophytes, suggesting reliance on both allochthonous and autochthonous energy pathways. 5. Our results suggest that E. sinensis is likely to exert a greater per capita impact on the macroinvertebrate communities in invaded systems than P. leniusculus, with potential indirect effects on productivity and energy flow through the community.
Extracted statement — Outcome of interaction: Impact
Research field: Ecology and Evolutionary Biology
Title: Invasive mutualisms and the structure of plant-pollinator interactions in the temperate forests of north-west Patagonia, Argentina
Abstract: 1 Alien species may form plant–animal mutualistic complexes that contribute to their invasive potential. Using multivariate techniques, we examined the structure of a plant–pollinator web comprising both alien and native plants and flower visitors in the temperate forests of north‐west Patagonia, Argentina. Our main objective was to assess whether plant species origin (alien or native) influences the composition of flower visitor assemblages. We also examined the influence of other potential confounding intrinsic factors such as flower symmetry and colour, and extrinsic factors such as flowering time, site and habitat disturbance. 2 Flowers of alien and native plant species were visited by a similar number of species and proportion of insects from different orders, but the composition of the assemblages of flower‐visiting species differed between alien and native plants. 3 The influence of plant species origin on the composition of flower visitor assemblages persisted after accounting for other significant factors such as flowering time, bearing red corollas, and habitat disturbance. This influence was at least in part determined by the fact that alien flower visitors were more closely associated with alien plants than with native plants. The main native flower visitors were, on average, equally associated with native and alien plant species. 4 In spite of representing a minor fraction of total species richness (3.6% of all species), alien flower visitors accounted for > 20% of all individuals recorded on flowers. Thus, their high abundance could have a significant impact in terms of pollination. 5 The mutualistic web of alien plants and flower‐visiting insects is well integrated into the overall community‐wide pollination web. However, in addition to their use of the native biota, invasive plants and flower visitors may benefit from differential interactions with their alien partners. The existence of these invader complexes could contribute to the spread of aliens into novel environments.
Extracted statement — Ecological Level of evidence: Individual
Research field: Ecology and Evolutionary Biology
Title: Facilitation and interference underlying the association between the woody invaders Pyracantha angustifolia and Ligustrum lucidum
Abstract: ABSTRACT Questions: 1. Is there any post-dispersal positive effect of the exotic shrub Pyracantha angustifolia on the success of Ligustrum lucidum seedlings, as compared to the effect of the native Condalia montana or the open herbaceous patches between shrubs? 2. Is the possible facilitation by Pyracantha and/or Condalia related to differential emergence, growth, or survival of Ligustrum seedlings under their canopies? Location: Cordoba, central Argentina. Methods: We designed three treatments, in which ten mature individuals of Pyracantha, ten of the dominant native shrub Condalia montana, and ten patches without shrub cover were involved. In each treatment we planted seeds and saplings of Ligustrum collected from nearby natural populations. Seedlings emerging from the planted seeds were harvested after one year to measure growth. Survival of the transplanted saplings was recorded every two month during a year. Half of the planted seeds and transplanted saplings were cage-protected from rodents. Results...
Extracted statement — Ecological Level of evidence: Individual
Research field: Ecology and Evolutionary Biology
Title: Enemy release or invasional meltdown? Deer preference for exotic and native trees on Isla Victoria, Argentina
Abstract: How interactions between exotic species affect invasion impact is a fundamental issue on both theoretical and applied grounds. Exotics can facilitate establishment and invasion of other exotics (invasional meltdown) or they can restrict them by re-establishing natural population control (as predicted by the enemy- release hypothesis). We studied forest invasion on an Argentinean island where 43 species of Pinaceae, including 60% of the world's recorded invasive Pinaceae, were introduced c. 1920 but where few species are colonizing pristine areas. In this area two species of Palearctic deer, natural enemies of most Pinaceae, were introduced 80 years ago. Expecting deer to help to control the exotics, we conducted a cafeteria experiment to assess deer preferences among the two dominant native species (a conifer, Austrocedrus chilensis, and a broadleaf, Nothofagus dombeyi) and two widely introduced exotic tree species (Pseudotsuga menziesii and Pinus ponderosa). Deer browsed much more intensively on native species than on exotic conifers, in terms of number of individuals attacked and degree of browsing. Deer preference for natives could potentially facilitate invasion by exotic pines. However, we hypothesize that the low rates of invasion currently observed can result at least partly from high densities of exotic deer, which, despite their preference for natives, can prevent establishment of both native and exotic trees. Other factors, not mutually exclusive, could produce the observed pattern. Our results underscore the difficulty of predicting how one introduced species will effect impact of another one.
Extracted statement — Ecological Level of evidence: Individual
Research field: Ecology and Evolutionary Biology
Title: Positive interactions among plant species for pollinator service: assessing the 'magnet species' concept with invasive species
Abstract: Plants with poorly attractive flowers or with little floral rewards may have inadequate pollinator service, which in turn reduces seed output. However, pollinator service of less attractive species could be enhanced when they are associated with species with highly attractive flowers (so called ‘magnet-species’). Although several studies have reported the magnet species effect, few of them have evaluated whether this positive interaction result in an enhancement of the seed output for the beneficiary species. Here, we compared pollinator visitation rates and seed output of the invasive annual species Carduus pycnocephalus when grow associated with shrubs of the invasive Lupinus arboreus and when grow alone, and hypothesized that L. arboreus acts as a magnet species for C. pycnocephalus. Results showed that C. pycnocephalus individuals associated with L. arboreus had higher pollinator visitation rates and higher seed output than individuals growing alone. The higher visitation rates of C. pycnocephalus associated to L. arboreus were maintained after accounting for flower density, which consistently supports our hypothesis on the magnet species effect of L. arboreus. Given that both species are invasives, the facilitated pollination and reproduction of C. pycnocephalus by L. arboreus could promote its naturalization in the community, suggesting a synergistic invasional process contributing to an ‘invasional meltdown’. The magnet effect of Lupinus on Carduus found in this study seems to be one the first examples of indirect facilitative interactions via increased pollination among invasive species.
Extracted statement — Ecological Level of evidence: Individual
Research field: Ecology and Evolutionary Biology
Title: Preferences of the Ponto-Caspian amphipod Dikerogammarus haemobaphes for living zebra mussels
Abstract: A Ponto-Caspian amphipod Dikerogammarus haemobaphes has recently invaded European waters. In the recipient area, it encountered Dreissena polymorpha, a habitat-forming bivalve, co-occurring with the gammarids in their native range. We assumed that interspecific interactions between these two species, which could develop during their long-term co-evolution, may affect the gammarid behaviour in novel areas. We examined the gammarid ability to select a habitat containing living mussels and searched for cues used in that selection. We hypothesized that they may respond to such traits of a living mussel as byssal threads, activity (e.g. valve movements, filtration) and/or shell surface properties. We conducted the pairwise habitat-choice experiments in which we offered various objects to single gammarids in the following combinations: (1) living mussels versus empty shells (the general effect of living Dreissena); (2) living mussels versus shells with added byssal threads and shells with byssus versus shells without it (the effect of byssus); (3) living mussels versus shells, both coated with nail varnish to neutralize the shell surface (the effect of mussel activity); (4) varnished versus clean living mussels (the effect of shell surface); (5) varnished versus clean stones (the effect of varnish). We checked the gammarid positions in the experimental tanks after 24 h. The gammarids preferred clean living mussels over clean shells, regardless of the presence of byssal threads under the latter. They responded to the shell surface, exhibiting preferences for clean mussels over varnished individuals. They were neither affected by the presence of byssus nor by mussel activity. The ability to detect and actively select zebra mussel habitats may be beneficial for D. haemobaphes and help it establish stable populations in newly invaded areas.
Extracted statement — Ecological Level of evidence: Individual
Research field: Ecology and Evolutionary Biology
Title: Ecology of brushtail possums in New Zealand dryland ecosystem
Abstract: The introduced brushtail possum (Trichosurus vulpecula) is a major environmental and agricultural pest in New Zealand but little information is available on the ecology of possums in drylands, which cover c. 19% of the country. Here, we describe a temporal snapshot of the diet and feeding preferences of possums in a dryland habitat in New Zealand's South Island, as well as movement patterns and survival rates. We also briefly explore spatial patterns in capture rates. We trapped 279 possums at an average capture rate of 9 possums per 100 trap nights. Capture rates on individual trap lines varied from 0 to 38%, decreased with altitude, and were highest in the eastern (drier) parts of the study area. Stomach contents were dominated by forbs and sweet briar (Rosa rubiginosa); both items were consumed preferentially relative to availability. Possums also strongly preferred crack willow (Salix fragilis), which was uncommon in the study area and consumed only occasionally, but in large amounts. Estimated activity areas of 29 possums radio-tracked for up to 12 months varied from 0.2 to 19.5 ha (mean 5.1 ha). Nine possums (4 male, 5 female) undertook dispersal movements (≥1000 m), the longest of which was 4940 m. The most common dens of radio-collared possums were sweet briar shrubs, followed by rock outcrops. Estimated annual survival was 85% for adults and 54% for subadults. Differences between the diets, activity areas and den use of possums in this study and those in forest or farmland most likely reflect differences in availability and distribution of resources. Our results suggest that invasive willow and sweet briar may facilitate the existence of possums by providing abundant food and shelter. In turn, possums may facilitate the spread of weeds by acting as a seed vector. This basic ecological information will be useful in modelling and managing the impacts of possum populations in drylands.
Extracted statement — Ecological Level of evidence: Individual