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Bell, Spencer Sullivan. "Mountain Lake Revisited: Impacts of Invasion on Native Symbiotic Systems." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/96193.
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Organismal invasions have repeatedly been cited as both a driving force behind global change and beneficiaries of that change. Although many drivers of these invasions have been well studied, few studies have addressed invasions through the perspective of native symbiont communities. In the Mountain Lake region of Virginia, crayfish host diverse assemblages of obligate cleaning symbionts known as branchiobdellida. This cleaning symbiosis has been found to result in significant fitness benefits for native crayfish. Historical survey work showed that invasive crayfish, known to be intolerant of symbionts, were introduced into the region by the 1960s. I carried out an extensive regional survey to determine how this invasion has progressed and what impacts it is having on the native crayfish-branchiobdellida symbiosis. Survey results show that invasive crayfish have successfully spread throughout the region, resulting in the displacement of native crayfish. Additionally, findings suggest that invasion results in significantly reductions in abundance and richness in native symbiont communities. To determine mechanisms contributing to observed impacts on native symbionts, I carried out a study that simulated displacement of native crayfish by invasive crayfish in a controlled setting. This study found that as native crayfish are increasingly displaced by invasive crayfish, both symbiont dispersal and survival are negatively affected. This potential loss of symbiosis caused by invasion may reduce symbionts on native crayfish below abundances necessary for fitness benefits, exacerbating the negative impacts of invasions and presenting a major conservation issue in invaded systems.M. S.
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Morghan, Kimberly Jo Reever. "Competitive interactions between native grasses and invasive species in California grasslands /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Jewett, Elizabeth Bromley. "Epifaunal disturbance by periodic low dissolved oxygen native versus invasive species response /." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2714.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2005.Thesis research directed by: Biology. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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MacNeil, Calum. "The ecology of freshwater amphipods : a study of invasive and native species." Thesis, Queen's University Belfast, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312638.
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Fincham, William Norman Whitlock. "Quantifying the impacts of invasive non-native species using key functional traits." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/21380/.
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Invasive non-native species place high pressures on native communities and can result in ecological impacts often associated with differences in key functional behaviours that mediate top-down and bottom-up forces. In this thesis, I use two model systems, the UK Coccinellidae system and the UK freshwater amphipod system, to quantify per-capita differences between native and invasive non-native species. I scale these studies up to more complex ecological communities and attempt to account for additional environmental pressures (e.g. pathogenic infection). First, I present a laboratory experiment to quantify the per-capita differences in predatory behaviour between native and invasive non-native Coccinellidae with a pathogen (Beauveria bassiana) exposure treatment. H. axyridis was the most effcient predator and pathogenic infection reduced the forage ability in all species. Second, I used existing H. axyridis distribution and aphid abundance data to quantify H. axyridis' impact through top-down forces. The arrival of H. axyridis is correlated with significant changes in aphid abundance and, of the 14 species studied, five declined in abundance, four increased, while the remaining five showed no significant change. Third, I measured the per-capita differences in detrital processing rates between native and invasive freshwater amphipods when provided with three diets of differing resource quality and maintained at three temperatures. The rates of detrital processing varied between the native and invasive non-native species and between the temperature and resource quality treatments. Fourth, I applied native and invasive amphipods at two density treatments (high and low) to a field mesocosm experiment to measure how the per-capita differences impacted more complex ecological systems. The presence of invasive amphipods changed the macroinvertebrate community composition and ecosystem functioning. I finish by highlighting that our understanding as to how the pressures of invasive non-native species interact with additional environmental stressors remains limited and an area that warrants further investigation.
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Costa, Sofia Conde. "Antagonistic interactions between dominant invasive and native ant species in citrus orchards." Master's thesis, ISA, 2017. http://hdl.handle.net/10400.5/14836.
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Mestrado em Engenharia Agronómica - Proteção das plantas / Instituto Superior de AgronomiaThe Argentine ant, Linepithema humile (Mayr) established in the South of Portugal (Algarve), about 120 years ago. Zina et al. (2017) compared the composition of ant communities foraging in tree canopy in citrus orchards among the three ecological subregions of Algarve (Litoral, Barrocal and Serra) and observed that the invasive dominant species L. humile was absent from Serra. In this work, we tested the hypothesis that dominant native ant species, such as Tapinoma nigerrimum (Nylander) and Lasius grandis Forel could prevent the Argentine ant from invading Serra. Laboratory experiments were carried out, using both Petri dish arenas and cages to assess the antagonistic interactions between the Argentine ant and two dominant native species, at the individual and colony level, respectively. Overall, our results support the tested hypothesis. At the individual level, both T. nigerrimum and L. grandis showed higher aggression and survival levels than Argentine ant. At the colony level, the results suggest that both the Argentine ant and T. nigerrimum were able to recruit a relative large number of individuals from the colony when trying to colonise a food resource defended by the competitor species. In our experimental conditions, T. nigerrimum showed to be more efficient than Argentine ant in this type of competition, as it was able to defend a food resource in four out of five times from the attack of the former species, as well as to dominate a resource defended by Argentine ant in four out of five times
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Mullins, Lydia R. "Testing the effects of glyphosate and a possible tradeoff with immunity on native and non-native species of crickets." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587642768787223.
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Wint, Ashley A. "Genetic Diversity in Native and Invasive Rubus (Rosaceae)." TopSCHOLAR®, 2008. http://digitalcommons.wku.edu/theses/17.
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Invasive species are an increasing threat to biological diversity as well as a leading cause of recent species’ extinctions. Invasives spread quickly and efficiently, and the U.S spends millions of dollars annually in the control and eradication of these species. More information is necessary in order to predict which species may become invasive. Rubus (Rosaceae) was chosen for study because this genus includes various ploidy levels, reproductive modes, and species that are invasive as well as native.
Three Rubus species were chosen to represent apomictic and tetraploid invasives (Rubus armeniacus), a sexual and diploid native species (R. occidentalis), and a sexual and diploid invasive species (R. phoenicolasius). Specimens were collected across the U.S. and two different genetic fingerprinting techniques were used; Amplified Fragment Length Polymorphism (AFLP) and Randomly Amplified Fingerprints (RAF).
Using three AFLP primers and two RAF primers, genetic similarity was determined and phylograms were constructed. Through statistical analysis and phylogram data it was determined that there might be slightly more genetic diversity in native R. occidentalis than in invasive R. phoenicolasius. Genetic diversity between apomictic and tetraploid Rubus armeniacus and the two sexual and diploid Rubus species were so similar that no distinction could be made, although the mean pairwise distances and mean number of alleles were significantly different. It was also found that geographic distance and genetic similarity do not appear to be related in these three Rubus species. During the course of this study it was also observed that the AFLP technique produced more alleles than the RAF technique, although this difference was not significant.
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Li, Yue. "Biodiversity in a Dynamic World: How Environmental Variability Influences Coexistence between Introduced and Native Species." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/604812.
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Understanding broad patterns of biodiversity requires developing a unified and rigorously tested theory that explains how species coexist despite the risk of competitive exclusion. Species interactions are fundamentally shaped by environmental variability. Recent theoretical development has predicted a set of general mechanisms that promote species coexistence under variable environments. Nevertheless, this theoretical framework has received limited empirical tests. Biological invasions offer excellent opportunities to empirically test coexistence mechanisms in communities in which the stability of coexistence is likely affected by introduced species. I took this opportunity to directly test the theory of species coexistence in this dissertation work by investigating how environmental variability affected the invasion of introduced species and their coexistence with native species. My collaborators and I started the investigation of diversity maintenance by first examining the range expansion of introduced species. Studying range shifts can reveal drivers of diversity patterns, which are formed by overlapping ranges of different species. We used a novel spatial analysis to determine the scale-dependent expansion rate of an invasive winter annual species, Brassica tournefortii over North America as well as to infer the drivers of this scale dependency. We found that this species expanded rapidly on scales from 5 to 500 km historically but had ceased its current expansion on the 100-500 km scales due to climatic constraints. This finding left open the question why this species continued its spread on the 5-50 km scales and how it would impact native species within its invaded range. To address these questions, we examined relatively local scale interactions between B. tournefortii and its competitors. We compared key demographic rates of B. tournefortii with other invasive and native winter annuals over a Sonoran Desert landscape to check conditions necessary for their spatial and temporal niche differentiation. We found the presence of two essential requirements for their niche differentiation: species-specific germination responses that could differentiate species by their favored environments and buffered population growth in time and space that could prevent catastrophic population declines when species faced unfavorable conditions. These conditions could provide niche opportunities to promote both the establishment of B. tournefortii and the persistence of native species under its presence. Building upon this finding, we directly quantified one general mechanism of spatial niche differentiation between B. tournefortii and its native competitors. We measured the strength of this mechanism, the spatial storage effect, across a hierarchy of spatial scales (subhabitat -> habitat -> landscape). We found that this mechanism did not promote species coexistence on any of these scales over the study period. These species were not differentiated over their tested spatial niches because weak competition following dry growing conditions failed to intensify intraspecific competition relative to interspecific competition. The strength of this mechanism increased from occasionally producing negative effects on lower scales to consistently being non-negative on the highest scale. This scale-dependent pattern was in line with the expectation that coexistence potential would increase with scales as species interacted over a wider range of environmental heterogeneity. Our findings demonstrated empirically that environmental variability in time and space led to scale-dependent patterns of the coexistence potential between introduced and native species. This work showed that introduced and native species could be differentiated by their environmental responses given spatial and temporal environmental heterogeneity on higher scales. However, for those species to stably coexist on higher scales, competitive effects had to follow environmental responses to separate species by their own density-dependent feedback loops. This work is among the first few empirical tests of a body of theory that holds the promise to generalize the mechanisms of spatial and temporal niche differentiation. Its success and limitation can motivate more studies to adopt the guiding mathematical principles and to use similar yet more innovative approaches to address the grand question of biodiversity maintenance.
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Curtis, Tracy Renee. "Mechanisms facilitating the success of an invasive social wasp species in North America relative to a native species." Diss., Online access via UMI:, 2005. http://wwwlib.umi.com/dissertations/fullcit/3164710.
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Beckmann, Michael [Verfasser]. "In Search of Similarities in Invasive Plant Species - Comparing Native and Invasive Populations of Six Clonal Plant Species in Germany and New Zealand / Michael Beckmann." Kiel : Universitätsbibliothek Kiel, 2018. http://d-nb.info/1153400855/34.
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Townhill, Bryony Lindsey. "Marine species and climate change : using modelling techniques to investigate effects on species distributions." Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/25283.
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Anthropogenic climate change is one of the main challenges affecting the globe, with particular implications for the oceans. Marine climate change research has moved forward rapidly in recent years, and a range of physical model outputs are available that can be used by ecologists to help predict how species might be affected into the future. Policy makers require a level of understanding of how certain species and their ranges might change so that they can respond with sustainable management actions. This thesis aims to make use of a number of modelling techniques to explore implications of past and future conditions for marine species, and to appraise those tools that can be used under differing circumstances. Policy questions are answered relating to changes in the abundance and distribution of marine species. The links between historical climatic conditions and Barents Sea cod abundance are explored using Generalised Additive Models using data collected in the middle of the 20th century. This valuable historical data indicated that cod have temperature preferences and expand and shift their distributions based on environmental conditions. A simpler modelling technique is used to examine how oxygen conditions have changed in recent decades in the North Sea, how they might change in the future, and what implications this has for commercial fish species. The models show that oxygen conditions have improved recently and that they will not decrease to levels that result in large negative effects in the coming century. Species distribution modelling using a combination of global and downscaled model outputs shows that the UK will become more suitable for some non-native and harmful algal species in the 21st century, and less suitable for others. The model outputs contribute to the understanding of climate change effects and development of management tools to ensure the resilience of marine ecosystems into the future.
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anderson, kaylee. "Using Linear Mixed Models to Analyze Native and Non-Native Species Abundances in Coastal Sage Scrub." Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/scripps_theses/807.
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Coastal Sage Scrub (CSS) is a low scrubland plant community native to the coasts of California, housing many threatened and endangered species. Due to the invasion of non-native plants, many areas of CSS have type converted to annual grasslands and the fire frequency has accelerated; fire in turn, may facilitate further invasion, leading to a loss of biodiversity. While many studies document post-fire succession in these communities, pre-fire data are rarely available for comparison, especially data on seedling emergence. I analyzed post-fire recovery of a type-converted grassland community, comparing seedling emergence data for the first and third year after fire to the three years preceding the fire. Non-native species abundances declined more after the fire than did native abundances. This pattern was still present in 2015, three years post-fire. Two native species, Amsinckia menziesii var. intermedia (Amsinckia) and Phacelia distans (Phacelia), were subjects of seed addition treatments pre-fire, but I found no evidence that past seeding increased their abundances post-fire. Amsincki did recover to its pre-fire density three years after the fire, while the density of Phacelia declined over 75% in both the year immediately post-fire and three years after the fire. However, a third native species, Lupinus bicolor (Lupinus), was both much more abundant and also more spatially widespread both immediately after the fire and two years later. This supports the hypothesis that Lupinus is stored in the soil seed bank and the fire may have given this species the opportunity to recover by lowering abundances of non-native competitors. This analysis will inform future conservation efforts by improving our understanding of how seed banks impact the post-fire recovery of native species.
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Henkanaththegedara, Sujan Maduranga. "Ecological Complexity of Non-Native Species Impacts in Desert Aquatic Systems." Diss., North Dakota State University, 2012. https://hdl.handle.net/10365/26697.
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Without an adequate understanding of complex interactions between native and non-native species, management of invasive species can result in unforeseen detrimental impacts. I used both field and laboratory experiments to study reciprocal species interactions between the endangered Mohave tui chub (Siphateles bicolor mohavensis) and invasive western mosquitofish (Gambusia affinis). I also examined the impacts of both fish species on the aquatic invertebrate communities in desert springs. I demonstrate a case of intraguild predation (IGP) as a mechanism facilitating co-persistence of the endangered Mohave tui chub with invasive mosquitofish using field mesocosm experiments. In this case of IGP, adult tui chub prey on adult and juvenile mosquitofish, while adult mosquitofish prey on tui chub eggs and/or larvae. I conducted laboratory predation trials to assess if IGP was size-structured due to predator gape-limitation. I explored sex specific differences in gape-size limitation in mosquitofish, because mosquitofish are sexually dimorphic. Larval tui chubs had lower survival in the presence of female mosquitofish than in the presence of males. Reciprocally, male mosquitofish had lower survival than the females in the presence of Mohave tui chub. These results combined with vulnerability modeling supported that IGP in this system is size structured based on gape-size limitation. These results collectively suggest size-structured IGP may facilitate the co-persistence of these two fish species. My findings also suggest that mosquitofish may not be a limiting factor for the persistence of the endangered Mohave tui chub. Further, habitats currently harboring mosquitofish were considered as future refuge habitats for Mohave tui chub, a management option previously un-available. In addition to such reciprocal interactions between fish species, recently established fish populations may impact unique invertebrate communities. Mesocosm experiments with sympatric and allopatric populations of tui chub and mosquitofish showed negative impacts of both fish species on changes of invertebrate community structure. Specifically, fish caused population declines and, in some cases, extirpations of various invertebrate taxa. These results suggest important conservation implications of invasive fish as well as protected fish transplants into fishless desert springs. Overall my research emphasizes the complexity of ecological interactions between native and non-native fish species in desert aquatic systems.
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Richards, Jeannine Hyde. "From 'useful and interesting' to 'evil invaders': evolving perceptions of non-native species in the United States." Thesis, Boston University, 2002. https://hdl.handle.net/2144/27749.
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Boston University. University Professors Program Senior theses.PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
2031-01-02
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Kajita, Yukie. "Reproductive Tactics of Aphidophagous Lady Beetles: Comparison of a Native Species and an Invasive Species that is Displacing It." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/137.
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Coccinella septempunctata L. (Coleoptera: Coccinellidae) has been introduced to North America in recent decades, raising concerns of adverse impacts on native lady beetles, including the congeneric C. transversoguttata richardsoni (Brown). The central focus of my dissertation is to understand the importance of reproduction, in particular, in promoting invasion of C. septempunctata and its replacement of native lady beetles in alfalfa fields of western North America. Studies were conducted to compare reproductive tactics of the invasive C. septempunctata and the native C. transversoguttata, by addressing: 1) maximum rate of reproduction of overwintered lady beetles, 2) population dynamics of the invasive and native lady beetles and their aphid prey, and seasonal reproductive patterns, over a 3-year period (2004'2006) in alfalfa fields, 3) reproductive tactics and plasticity in response to various prey availabilities, and 4) ovarian dynamics and observation of oosorption in response to prey removal. The invasive C. septempunctata gained a reproductive advantage over native, North American lady beetles from its larger body size when feeding on abundant prey. The invasive species gained additional advantage by its allocation of prey to larger numbers of relatively small eggs. In alfalfa fields, females of C. septempunctata reproduced more readily and laid more eggs than females of C. transversoguttata even at low prey density. C. septempunctata females collected from the field were also more successful in approaching their maximum body weights and reproduction, as observed under ideal conditions, than were females of native C. transversoguttata. In the laboratory, C. septempunctata females produced larger numbers of relatively small eggs, and they maintained their body weights even as they were producing eggs at low rates when aphids were provided in limited numbers. More immediate adjustment of reproductive effort with prey removal, and higher recovery of reproductive rate when prey again became available, were observed in C. septempunctata, compared with C. transcersoguttata. These reproductive abilities of C. septempucntata may contribute to its invasion success and dominance in alfalfa fields. Further studies are needed to determine why females of C. septempunctata are in better physiological condition than are females of C. transversoguttata in spring alfalfa fields.
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Schwartz, Lauren Michele. "The competitive response of Panicum virgatum cultivars to non-native invasive species in southern Illinois." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/765.
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Historically, the tallgrass prairie (TGP) was the largest ecosystem in North America, but today only about 10-15% of the original extent exists today. Some areas have experienced more extreme loss, for example in the state of Illinois less than 0.01% of high-quality native tallgrass prairie remains. Non-native invasive species are a recent phenomenon that threatens the integrity of surviving TGP communities. Ecotypes of dominant C4 grasses are the basis of numerous cultivars, many of which are utilized in prairie restorations. In this study, the effects of three invasive species (Bromus inermis, Schedonorus phoenix, and Poa pratensis) on two lowland (`Alamo' and `Kanlow') and three upland (`Blackwell', `Cave in Rock', and `Trailblazer') cultivars of the dominant C4 grass Panicum virgatum were tested. Two simple pair-wise greenhouse experiments were established in which cultivars were sown as a monoculture or as a mixture of the cultivars with one of three invasive species. Pots were subjected to one of two water treatments with three replicates of each treatment combination. Response variables (height, number of leaves, tiller density, and biomass) and resources (soil moisture, soil pH, soil electrical conductivity, and light intensity) were measured. The greenhouse studies showed that response variables were affected by the presence of invasive species and that the time of growth affected resource levels. Resources are allocated to different areas (i.e growth and reproduction) when competition and stress are implemented on the dominant species. This study was the first to experimentally test for the presence of the physiological stress marker, trigonelline, in a prairie grass. Trigonelline was highest in upland cultivars under low moisture and highest in lowland cultivars under low moisture treatments. The results of these greenhouse studies suggest that invasive species may differentially affect cultivars of Panicum virgatum that may be sown in a prairie restoration. Performance of the P. virgatum cultivars was dependent on the timing of growth, the pot size, the invasive species, as well as soil moisture level. Therefore, when choosing a cultivar source for restoration, resources (i.e. soil moisture) should be looked into to maximize the output of the cultivar.
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Fisher, Alison J. "Ecology and genetics of the fungal pathogen Claviceps purpurea on native and invasive Spartina species /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Bunke, Mandy. "A new look at factors influencing intraguild predation and cannibalism between native and invasive species." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/22108/.
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Da, Silva Elizabeth M. "Pollinator-mediated impacts of the invasive plant species Lythrum salicaria on the native Decodon verticillatus." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28910.
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Plant-pollinator interactions in invaded communities can range from facilitative to competitive, with the latter being most commonly observed. If invasive species can successfully integrate into native plant-pollinator networks and change pollinator foraging patterns, native plant fitness in these communities could be altered.
Here I examine the impact of the showy flowering invasive plant, purple loosestrife (Lythrum salicaria), on a co-flowering close relative, swamp loosestrife (Decodon verticillatus). Both species are in the family Lythraceae, share a number of floral traits, and tend to be visited by the same pollinator community. A pollen limitation experiment was conducted in invaded and uninvaded populations of D. verticillatus on Lake Opinicon, Ontario, to determine if the presence of the L. salicaria altered pollinator driven reproductive success in D. verticillatus. These experiments demonstrated that invaded communities suffer less pollen limitation than uninvaded communities, suggesting that there could be a positive impact of invasion on this particular measure of plant fitness. Complementary pollinator observations conducted at the same sites determined that the facilitative effect was not due to increased pollinator visitation to D. verticillatus, but rather suggest that there are differences in pollinator foraging patterns on inflorescences in invaded and uninvaded sites. While greenhouse experiments revealed a negative impact of L. salicaria pollen deposition on seed set in D. verticillatus, our field experiments suggest that invasive pollen transfer to natives in situ is not great enough to significantly mitigate the facilitate effects of an invasion on seed set.
This work provides a unique contribution to the field of pollination biology as well as our understanding of the impacts of plant invasions, and suggests that positive as well as negative consequences for natives should be considered when investigating community impacts on plant invasion.
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Gwinn, R. Nathan, and John L. Koprowski. "Differential response to fire by an introduced and an endemic species complicates endangered species conservation." ASSOC TERIOLOGICA ITALIANA, 2016. http://hdl.handle.net/10150/625219.
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Fire is a natural component of, and serves as a tool for, the restoration of forested ecosystems worldwide; however, disturbance due to fire also has been implicated in the proliferation of invasive species. How these fires affect occupancy and use of the forest by wildlife is of great concern, in particular, the differential response of non-native and native species. In the North American Southwest, prior to European settlement, frequent wildfires helped to maintain forest structure. We examined the effect of a large wildfire on an introduced population of the Abert's squirrel (Sciurus aberti) that has invaded the high elevation forests inhabited by the critically endangered Mt. Graham red squirrel (Tamiasciurus fremonti grahamensis). We found that introduced Abert's squirrels were more common than native red squirrels in burned areas. Abert's squirrels did not abandon burned areas but nested, foraged, and did not adjust their home range size in burned areas. This suggests that invasive Abert's squirrels are better able to exploit burned areas than native red squirrels and that fire can favor non-native species. This interaction between non-native species, native species, and fire adds new insight into the complexities of conservation and restoration of ecosystems and helps to inform conservation activities worldwide.
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Bailey, R. J. E. "Predatory interactions between the invasive amphipod Gammarus tigrinus and the native Opossum shrimp Mysis relicta." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368463.
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Hua, Yujie. "Changes of Soil Biogeochemistry under Native and Exotic Plants Species." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/1912.
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Invasive plant species are major threats to the biodiversity and ecosystem stability. The purpose of this study is to understand the impacts of invasive plants on soil nutrient cycling and ecological functions. Soil samples were collected from rhizosphere and non-rhizosphere of both native and exotic plants from three genera, Lantana, Ficus and Schinus, at Tree Tops Park in South Florida, USA. Experimental results showed that the cultivable bacterial population in the soil under Brazilian pepper (invasive Schinus) was approximately ten times greater than all other plants. Also, Brazilian pepper lived under conditions of significantly lower available phosphorus but higher phosphatase activities than other sampled sites. Moreover, the respiration rates and soil macronutrients in rhizosphere soils of exotic plants were significantly higher than those of the natives (Phosphorus, p=0.034; Total Nitrogen, p=0.0067; Total Carbon, p=0.0243). Overall, the soil biogeochemical status under invasive plants was different from those of the natives.
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Sarvela, Erika Renee. "DIFFERENTIATING BETWEEN INVASIVE AND NATIVE POPULATIONS OF BIGHEAD AND SILVER CARP USING MS-AFLP." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2807.
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When a species is introduced outside their native range, the genetic diversity of the introduced population is generally decreased due to the founder effect, and the fitness of individuals in the introduced population may decrease due to inbreeding depression. Invasive species are a paradox to this paradigm because while the initial population size of an invasive species may be small in their non-native range, the individuals are able to survive, eat, and reproduce so successfully, that they have deleterious effects on native species. One mechanism that invasive species use to overcome a lack of genetic diversity and adapt to their new environment is CpG methylation, a heritable and environmentally influenced epigenetic modification that regulates the expression of certain genes to alter phenotypes without altering an organism’s DNA sequence.Bighead and silver carps, two species of bigheaded carp native to eastern Asia, are believed to have been introduced to the United States in the 1970s. Since that time, populations of both bighead and silver carp have surged, particularly in the Mississippi River drainage, where they compete with native planktivores for food, injure boaters, and threaten the multi-million dollar fisheries industry in the Great Lakes. In this study, methylation-sensitive amplified fragment length polymorphisms (MS-AFLPs) were used to analyze the genetic and epigenetic diversity of bighead and silver carp from the Gan, Pearl, and Yangtze rivers in their native China and from the Illinois River in the United States. While the heterozygosity of silver carp in Illinois was not found to be significantly lower than that of silver carp in China, the silver carp in Illinois did show a significantly higher level of methylation compared to Chinese silver carp. There is evidence that CpG methylation may play a significant role in allowing silver carp to adapt and thrive in an introduced environment.
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Lehr, Gavin Charles, and Gavin Charles Lehr. "Symbiosis in the Context of an Invasive, Non-Native Grass: Fungal Biodiversity and Student Engagement." Thesis, The University of Arizona, 2018. http://hdl.handle.net/10150/626728.
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Grasslands in the western United States face severe environmental threats including those brought about by climate change, such as changes in precipitation regimes and altered fire cycles; land-use conversion and development; and the introduction, establishment, and spread of non-native species. Lehmann’s lovegrass (Eragrostis lehmanniana) was introduced to the southwestern United States in the early 1900s. Since its introduction, it has become the dominant grass in the mid-elevation grasslands of southern Arizona, including the Santa Rita Experimental Range (SRER), where it has displaced native grasses including Arizona cottontop, three awns, and gramas. Like all plants in terrestrial ecosystems, this grass harbors fungal symbionts that can be important for its establishment and persistence. This thesis focuses on fungal symbionts of Lehmann’s lovegrass and has two components. First, the diversity and distributions of endophytes in Lehmann’s lovegrass are evaluated in the context of biotic and abiotic factors in the SRER. Culturing from roots and shoots of Lehmann’s lovegrass at points beneath and outside the canopy of native mesquites, which are encroaching on grasslands over time, provides insight into how a single plant species can exhibit local variation in the composition of its symbionts. Second, the thesis is used as the basis for engagement of students in science, technology, engineering, and mathematics (STEM) through the development and implementation of classroom- and field activities centered on endophytes, which help high school students address core learning aims while also gaining real research experience. Engaging students in important questions relevant to their local environment can catalyze interest in science and help students cross the threshold into research. The contributions of such approaches with respect to learning not only fulfills key next-generation science standards and common core objectives, but provides students with a meaningful introduction to the excitement, importance, and accessibility of science.
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Nghidinwa, Kirsti C. "Why are some species invasive? : determining the importance of species traits across three invasion stages and enemy release of southern African native plants in New Zealand." Lincoln University, 2009. http://hdl.handle.net/10182/1438.
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There are many factors that have been proposed to contribute to plant invasiveness in nonnative ecosystems. Traits of invading species are one of them. It has been proposed that successful species at a certain invasion stage share particular traits, which could be used to predict the behaviour of potentially invasive plants at the respective stage. Three main stages of invasion are distinguished: introduction, naturalization, and invasion. I conducted a stageand trait-based analysis of available data for the invasion of New Zealand by the flora of southern Africa. Using 3076 southern African native vascular plant species introduced into New Zealand, generalised linear mixed model analysis was conducted to assess association of several species traits with the three invasion stages. The results showed that plant traits were significantly associated with introduction but fewer traits were associated with naturalization or invasion, suggesting that introduction can be predicted better using plant traits. It has been also hypothesized that species may become invasive in non-native ecosystems because they are removed from the regulatory effects of coevolved natural enemies (Enemy Release hypothesis). A detailed field study of the succulent plant Cotyledon orbiculata var. orbiculata L. (Crassulaceae) was conducted in the non-native New Zealand and native Namibian habitats to compare the extent of damage by herbivores and pathogens. C. orbiculata is a southern African species that is currently thriving in New Zealand in areas seemingly beyond the climatic conditions in its native range (occurring in higher rainfall areas in New Zealand than are represented in its native range). As hypothesised, C. orbiculata was less damaged by herbivores in New Zealand but, contrary to expectation, more infected by pathogens. Consequently, the plant was overall not any less damaged by natural enemies in the non-native habitat than in its native habitat, although the fitness impacts of the enemy damage in the native and invaded ranges were not assessed. The results suggest that climatic conditions may counteract enemy release, especially in situations where pathogens are more prevalent in areas of higher rainfall and humidity. To forecast plant invasions, it is concluded that species traits offer some potential, particularly at the early stage of invasion. Predicting which introduced plants will become weeds is more difficult. Enemy release may explain some invasions, but climatic factors may offset the predictability of release from natural enemies.
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Kovalenko, Katya. "Indirect effects of invasive species community effects of invasive aquatic plant control and direct and indirect effects of non-native peacock bass /." Diss., Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-06252009-203011.
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Selge, Sebastian. "Public and scientific discourses on biological invasions : social representations of invasive non-native species in Scotland." Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=183833.
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Invasive non-native species are believed to be one of the biggest threats to biodiversity. Until now biological invasions have been mainly studied from a biological perspective and much research has been undertaken to investigate species’ ecology and potential options for management. Comparatively little attention has been devoted to questions regarding the social construction of the issue. This is despite invasion biologists increasingly acknowledging the fundamental importance of human perceptions, beliefs, attitudes and values inherent in debates about invasive non-native species. This thesis employs a mix of methods from the social sciences to investigate the social construction of biological invasions. Research conducted here is based on the theory of social representations. Thus, taking a social scientific perspective, the thesis contributes to both the development of the theory and an identification of beliefs inherent in the debate on biological invasions and their relationship to people’s attitudes towards species and their management. Those species attributes that predominantly shape the debate – but yet appear to be under-researched – are identified. Based on the findings in this thesis I argue that invasion biology would benefit from a more explicit and transparent use of its concepts and terminology. This will have implications also for the communication with policy makers, conservation managers and the general public. Recommendations for future research are discussed along with limitations of the thesis.
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liu, xian. "PREDICTION OF NON-NATIVE INVASIVE PLANT SPECIES OCCURRENCES IN RELATION TO ENVIRONMENTAL VARIABLES IN SOUTHERN ILLINOIS." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/dissertations/1911.
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Non-native invasive plants are destructive plants brought into places where they did occur before naturally. The rapid spread of non-native invasive plants has become an urgent threat to ecosystems at a global scale, and it is a top priority problem for natural resources management. The overall objective of this project is to predict the occurrence of some common non-native invasive plants species in Southern Illinois to allow management policies to be developed.Seventeen of the most common and abundant non-native invasive species in Southern Illinois were analyzed. Eleven environmental variables were used to model species distributions and estimate their importance to species distributions. Results showed that land cover and soil (major land resource area) were the two most significant variables related to most of focal species distributions and made the most contributions in this study. Prediction maps indicated that most species had high probabilities of occurrence at the central south and along the riversides of the Southern Illinois area. To explore how climate change affects species invasions and habitats, an ensemble of 5 commonly used atmosphere-ocean general circulation models (AOGCMs) (CanESM2, CCSM 4.0, CGCM3.0, CSIRO MK3.5, and NorESM) were used to project future climate conditions. Overall, land cover and soil types (major land resource area) were the two most significant non-climate variables related to most of focal species distributions. Species with a narrow habitat or which preferred specific habitats would be mostly affected by land cover types and soil types while species (e.g., Lonicera maackii) having wide habitat tolerance would be least impacted. Prediction maps showed that most species had distribution trends from east to west in the central south area or from central south to north east. The center of the southern part of the area dominated by the Shawnee National Forest was predicted to have the most suitable habitats for all focal species except for Humulus japonicus and Phragmites australis. The predicted distributions under climate scenarios indicated that species distributions could change or shift under different representative concentration pathways (RCPs) and potential suitable habitat might expand under climate change. Change detection was conducted to quantitatively examine how changing climate could affect invasive species’ potential habitats. The five species with the most species records were evaluated for this analysis. For these species, potential suitable habitats were most likely to expand in the central west of study area for all climate change scenarios. Species suitable habitats would shift under climate change. Functional group and phylogenetic group analyses were conducted to investigate how species groups affect species spatial distributions and how evolutionary related nonnative invasive species distribute spatially. The 17 focal species were grouped into 4 broad functional groups (Woody and shrub species -FG1, herbaceous species -FG2, grass species -FG3, and vine species -FG4) based on life form. AUC indicated that model performance of functional groups was no better than of individual species alone. Land cover was the variable with the largest variable contribution to the predicted distributions of FG1, FG3, and FG4 while maximum temperature had the largest contribution for FG2. Composite maps for the functional groups showed that the central south dominated by the Shawnee National Forest was predicted as the most suitable habitats for all four functional groups. The composite maps for these functional groups were similar to the maps for the individual species within each own functional group. Genetic sequences of each species were used to construct a phylogeny. Besides the 17 focal species, an outgroup species Berberis vulgaris was added into the model to root the phylogenetic tree. Based on the resulting phylogenetic tree, species were classed into 3 groups (superasterids-PG1, monocots-PG2, and superrosids-PG3) based phylogenetic relativeness and distance. AUC indicated that model performance of phylogenetic groups was no better than of individual species alone. Variable contributions of functional groups indicated that landcover was the most significant variable for all three PGs. Composite maps showed the central south was predicted as hotspot. Phylogenetically related species responded similarly to the single species. This study focused on the prediction of non-native invasive species distributions in relation to environmental variables. Environmental factors that significantly affect invasive species distributions can indicate natural resource managers when conducting invasive species management is necessary. The approach of studying how invasive species respond to climate change can be extended to other invasive species research. By integrating functional groups and phylogenetic groups into species distribution predictions, species with too few records for modeling can be examined with abundant species in the same functional or phylogenetic group in predicting distributions. However, this research did not study how interspecific interactions (i.e, competition) between native and invasive species would affect species invasion. Further research of intergrating biotic factors is needed.
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Megyeri, Krisztian. "The Impact of Ambrosia trifida (giant ragweed) on Native Prairie Species in an Early Prairie Restoration Project." ScholarWorks@UNO, 2011. http://scholarworks.uno.edu/honors_theses/2.
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As the ecological importance of prairies is becoming more recognized, the number of prairie restoration projects is increasing worldwide. One of the major challenges in restoring any disturbed ecosystem is the successful establishment of native species at the expensive of invasive species. While some weedy species are gradually replaced as other, more desired, species become established, there are invasive species that, due to their level of dominance, may out-compete native species indefinitely. The objectives of this study were 1) to quantify the impact of Ambrosia trifida (giant ragweed) on the plant community of a newsly established prairie, 2) to assess any difference in effectiveness between management practices (cutting versus pulling) of A. trifida, and 3) to establish a baseline vegetation survey to be used in future evaluations and research of the prairie. In March of 2011, 30 plots (each 3 m2) were established within the 20 acre prairie including 10 control plots [C], 10 plots where A. trifida was selectively cut approximately 10 cm above ground level [Rc], and 10 plots where A. trifida was selectively pulled [Rp]. Treatment (cutting/pulling) was applied three times (April, June, and August) during the study, and in order to compare the effectiveness of the treatments, the number of removed A. trifida was recorded for the first two applications. Between April and June, the number of A. trifida decreased by a mean of 34.9 individuals in the cut plots, and increased by a mean of 12.4 individuals in the pulled plots suggesting (albeit, not significantly) that pulling may disturb the ground and promote the germination of more seeds from the seedbed. Final biomass data collection was conducted in mid August by removing the above ground biomass of all plants excluding A. trifida from four subplots within each of the 30 main plots, followed by drying and weighing of all biomass. A total of 172 plants from 30 species were removed for a total biomass of 1735.10 grams. In the control plots the mean biomass was 6.73g and the species diversity (H') was 0.037. In the treatment plots, the corresponding values were 83.39g, and 2.093. This twelve-fold difference in biomass suggests that the presence of A. trifida has a remarkable impact on the overall community of this newly established prairie and that the correct management of A. trifida could expedite the restoration process.
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Durant, Cheyenne Elizabeth. "Invasions in the Prairie Pothole Region: Addressing the Effects of Exotic Plants on Wetland and Grassland Ecosystems and Restoration Efforts." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31750.
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Three wetland restoration methods: seeding, seeding + hay mulch, and seeding + hay mulch + vegetation plugs were compared via the plant community within a formerly cropped wetland in southeastern North Dakota. Arrangement of plugs were also compared to assess the success of native species establishment. Mean relative cover for native species and introduced species were recorded and analyzed to compare the restoration methods and plug arrangement. Three herbicide treatments were studied on upland prairie sites with and without prescribed burning to test effects on leafy spurge (Euphorbia esula) control and seeded native establishment. There is no difference native species richness between the restoration methods six years post restoration, and no difference in plant cover in the different arrangement of plugs. Quinclorac significantly reduced leafy spurge cover; however, glyphosate treatments had higher cover of seeded native species.
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Avanesyan, Alina. "Native versus Exotic Grasses: The Interaction between Generalist Insect Herbivores and Their Host Plants." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406808876.
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Pieterson, Elisabeth Corrie. "Nature versus Nurture: The Influence of Phylogenetic Relatedness, Origin, and Environment on Native and Introduced Woody Shrubs in the Eastern United States." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534521742118989.
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Snyder, Matthew Robert. "Environmental DNA Detection and Population Genetic Patterns of Native and Invasive Great Lakes Fishes." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1564680483342507.
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King, Rachel A. "The Effects of Invasive Grasses on the Survival and Germination of Native Forbs." Scholarship @ Claremont, 2012. http://scholarship.claremont.edu/scripps_theses/110.
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Invasive species are an increasingly severe conservation problem that can dramatically alter native plant communities. Although ecologists have proposed many mechanisms for the dominance of invasive species, superior competitive ability is one of the longest standing hypotheses. In winter annual plant communities, germination timing affects competition among plants. I hypothesized that grass invasion has changed the costs and benefits of early and late germination, and that species with flexible germination timing would compete better with invasives. Experiments at the Bernard Field Station in Claremont, CA and germinator trials in a controlled environment were used to examine the survivorship and germination rate of three native forbs in the presence or absence of invasive grass competition. Germinator trials revealed that most Clarkia purpurea seeds germinated in fall conditions, though newer seeds had higher proportions germinate under winter conditions. Older seeds had a lower germination success, indicating a potential decrease in seed viability. In the field experiment, November germinants had higher survival rates than October germinants for Amsinckia menziesii and Phacelia distans, and both species had similar numbers of new germinants at each census. Removal of invasive grasses did not significantly affect the survival of either species, though a trend towards increased survivorship was observed in removal plots of November germinants. Taken together, these results show evidence for variation in germination timing and responses to environmental cues among native annual seeds, and also support the idea that germination timing has important consequences for survivorship, and potentially competitive interactions, with invasive grasses.
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Crous, Casparus Johannes. "Vulnerability of selected native and invasive woody species to streamflow variability in Western Cape fynbos riparian ecotones." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4203.
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Thesis (MScConsEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: Riparian ecosystems of the Mediterranean south-western Cape region are projected to experience significant decreases in streamflow due to climate change and increased demands for water associated with human demographic trends and increasing living standards. Aggravating this problem are woody invasive alien plants, such as Acacia mearnsii, whose impacts, including those on catchment water yields, have justified extensive eradication programmes such as Working for Water (WfW). WfW has been highly successful in managing invasive alien species in some areas, while at the same time enhancing the quality of life of poor South Africans. Unfortunately, the managers of these eradication initiatives often experience a lack of information on the species- and site-specific ecological properties that may aid in prioritising sites more prone to invasion, essentially inhibiting accurate management output. Knowledge, such as that associated with the possible future distribution of invasive species in a changing environment, may help to optimise eradication initiatives. I therefore determined whether woody plants portray different physiological (vulnerability to cavitation) and wood anatomical traits (wood density, vessel resistance to implosion, vessel lumen and wall diameters) across three prominent riparian zones in the south-western Cape that each differ in streamflow quantity – to gain a mechanistic understanding of how woody species, especially invasive species, adapt their hydraulic strategy across this proxy for water availability. Using factorial ANOVA’s, to distinguish any differences in plant physiological and wood anatomical responses to water availability within and between species, showed Acacia mearnsii having consistently higher drought-tolerance (lower P50 values and denser wood) compared to native species under reduced water availability. These results supported the significant variation in drought-tolerance strategies that exist within and between taxonomically different species across different environments. Water availability thus has a strong selective effect on functional traits of species; however, minimum water potentials were more useful in describing in situ hydrological conditions than streamflow. Additionally, a non-causal relationship between wood anatomical traits and drought-induced cavitation was observed. Therefore, using only wood anatomical measurements to assess drought-tolerance of species might not be accurate across all species. This mechanistic approach to assess the invasive potential of species under projected drier conditions has great practical value. It can be used to improve species selection for restoration initiatives, and is of great value for future use in prioritizing eradication programmes.
AFRIKAANSE OPSOMMING: Rivieroewer ekosisteme in die Mediterreense Suidwes-Kaap streek kan groot afnames in stroomvloei verwag, wat meestal toegeskryf kan word aan klimaatsverandering en die verhoogde aanvraag na water geassosieerd met stygende populasiegrootte. Uitheemse indringerplante soos Acacia mearnsii vererger hierdie probleem. Laasgenoemde spesies plaas groot druk op opvanggebiede se water opbrengs, en vorm grootliks die rede waarom uitroeiing programme soos Werk vir Water (WfW) gestig is. WfW het al groot suksesse behaal in die bestuur van uitheemse indringerplante, en terselfdertyd die lewenskwaliteit van arm Suid-Afrikaners verhoog. Ongelukkig sukkel hierdie indringer uitroeiing inisiatiewe telkens met ongenoegsame bewyse wat kan help om leiding te verskaf by die prioritisering van areas meer geneig tot indringing. Die gevolg is dat onvoldoende bestuurs besluite gemaak kan word. Gevolglik sal kennis geassosieerd met die moontlike toekomstige verspreiding van hierdie indringerplant in ʼn veranderlike omgewing help om uitroeiing programme meer akkuraat te stel en gevolglik waardevol wees t.o.v. prioritisering van kwesbare areas. Die doel van hierdie studie was om die kwesbaarheid van sleutel inheemse houtagtige rivier spesies en veral die dreigende indringerplant Acacia mearnsii, te bestudeer in terme van verlaagde stroomvloei soos voorspel vir die Wes-Kaap fynbos ekosisteem. Deur te bepaal of houtagtige plante verskillende fisiologiese (kwesbaarheid teen xileem blokkasie) en anatomiese (hout digtheid, vat weerstandbiedendheid teen inmekaarkolking, vat holte en wand deursnee) hidrologiese eienskappe tentoonstel gemeet tussen drie prominente rivieroewer sones in die suidwes Kaap wat variëer in stroomvloei kwantiteit, verskaf ʼn meganistiese begrip van hoe spesies, veral die indringerplante, hul hidrologiese strategieë ten opsigte van droogtes kan aanpas. Faktoriële ANOVAS’s tussen spesies en liggings het getoon dat beide plant fisiologiese en hout anatomiese data beduidend variëer tussen taksonomies verskillende spesies. Veral Acacia mearnsii het deurgaans laer P50 waardes asook hoër houtdigtheid getoon, ‘n teken van hierdie spesies se verhoogde droogte toleransie in vergelyking met die inheemse spesies. Wat beduidend is is dat spesies-spesifieke lewensstrategieë ten opsigte van droogte toleransie in hierdie rivieroewer sones voorkom. Resultate het bevestig dat water beskikbaarheid ʼn groot rol speel in die seleksie van funksionele karaktereienskappe in plante, maar, dat minimum water potensiaal meer akkuraat was om in situ hidrologiese toestande te beskryf as wat stroomvloei kon. Die verhouding tussen plant fisiologiese en hout anatomiese karaktereienskappe was indirek as gevolg van spesies-spesifieke lewensstrategieë. Gevolglik sal die allenige gebruik van hout anatomiese eienskappe om droogte toleransie in plante te assesseer onakkuraat wees omdat daar ʼn swak verhouding tussen hout anatomie en droogte-geïnduseerde xileem blokkasie bestaan. ʼn Meganistiese benadering om die indringing potensiaal van spesies onder voorspelde droër kondisies te assesseer, asook om spesies seleksie vir restourasie doeleindes op te skerp, is prakties uitvoerbaar, en van groot waarde vir toekomstige gebruik in uitroeiing en restourasie inisiatiewe.
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Priddis, Edmund R. "Niche Separation Along Environmental Gradients as a Mechanism to Promote the Coexistence of Native and Invasive Species." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2199.pdf.
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Yuan, Wei. "The effects of non-native species on two life-stages of the Eastern oyster Crassostrea virginica." Master's thesis, University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6389.
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Since their recent introductions into Florida waters, three nonnative species [Perna viridis Linnaeus, 1758 (Asian green mussel), Mytella charruana d'Orbigny, 1846 (charru mussel) and Megabalanus coccopoma Darwin, 1854 (pink titan acorn barnacle)] have expanded both north and south along the Atlantic coast. Very little research has been done to understand how these nonnative species interact with the native eastern oyster (Crassostrea virginica Gmelin, 1791), which is a keystone species that provides important ecological services and economic benefits. To test the potential effects of P. viridis, M. charruana and M. coccopoma on C. virginica, I addressed the following questions: 1a) Does the presence of nonnative species decrease oyster larval settlement? 1b) Do oyster larvae avoid settling on oyster shells to which nonnative species are attached? 2a) Do nonnative species decrease survival of juvenile oysters (spat)? and 2b) Do nonnative species hinder spat growth? My manipulative experiments showed that the tested nonnative species influenced settlement, growth and survival of C. virginica in unique ways. Megabalanus coccopoma decreased the total number of settled oyster larvae, but did not influence larval preference or survival and growth of spat. Perna viridis negatively influenced larval settlement and oyster larvae avoided settling on shells of P. viridis. Mytella charruana had no influence on the total number of settled larvae but oyster larvae avoided settling on oyster shell with M. charruana or on the mussel shells themselves. Furthermore, both nonnative mussels negatively affected the survival of juvenile oysters, but only M. charruana reduced spat growth. These three nonnative species should be classified as invasive species because all had negative effects on the native oyster C. virginica.M.S.
Masters
Biology
Sciences
Biology
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Kinyo, Anthony Steven. "EFFECTS OF DISTANCE FROM INVASIVE LYTHRUM SALICARIA ON POLLINATOR VISITATION RATE AND REPRODUCTIVE SUCCESS IN NATIVE LYTHRUM ALATUM." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1127925607.
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Forget, Gabrielle. "A Meta-analysis of Evolutionary Responses in Native Plants to Introduced Plant Species: Does Phylogenetic Distance Play a Role?" Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35773.
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While there is increasing interest in the evolutionary consequences of species invasions on native plant communities, the connection between the phylogenetic relatedness of invaders and natives, and its evolutionary consequences, has not yet received much attention. One way to examine the role of relatedness on the impact of species invasions is through the use of meta-analytical techniques combined with a phylogenetic framework. I apply this technique and expand on a prior meta-analysis by Oduor (2013), in order to compare how native plant species that either have prior experience coexisting with an invasive (‘experienced’) or do not (‘naïve'), differ in terms of their growth and reproduction in the presence of the invasive for evidence of a phylogenetic signal in their response to plan invasions. My results suggest that the effects of a species invasion on native growth and reproductive traits may be greater when the native and invasive species are distantly related, and/or when the invasive species is allelopathic, but only in the presence on the invader. I also found that the negative effect of competition with an invader on native growth traits tended to be greatest when the native and invasive species were closely related, suggesting that the strength of competition and the evolutionary response of native plants to invasive plants may not be as closely associated as it is often assumed. Overall, my analysis suggests that future studies may benefit from integrating phylogenetic relatedness when exploring native evolutionary responses to invasions, but that considerable work need sot be done to tease apart the roles of relatedness and competition.
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Everling, Sanne. "The effect of temperature on the interaction between larvae of a native and a range expanding dragonfly species." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-446881.
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Climate change might affect the distribution of species; therefore, it is important to anticipate the imminent impact of climate change. Even though climate responses have the potential to affect species interactions, most models on the effect of climate change on species distribution assume that species respond to climate individually. Hence studies on competition effects are needed. In this study, I estimated growth, mortality, and behaviour (prey capture success, activity, exploration and boldness) at 20° C and 23° C at intra- and interspecific competition conditions in larvae of a native and a northward dispersing dragonfly. The results showed that the northward expanding Sympetrum fonscolombii had a higher growth and survival rate compared to the native Sympetrum vulgatum at interspecific conditions. At intraspecific conditions the results showed that temperature had no significant effect on the performance of S. fonscolombii, but S. vulgatum showed both a higher growth rate and a higher mortality at 23 ° C. A significant difference between temperatures within prey capture success rate was found in S. vulgatum only, during the second observation period. There was a correlation between activity and exploration in both species, between prey capture success rate and activity during the third observation round in S. vulgatum, and between prey capture success rate and boldness during the first observation round in S. fonscolombii. No other behaviours were correlated. Prey capture success rate was shown to be repeatable in both species, while boldness was repeatable in S. vulgatum only. The behavioural results suggests that behavioural traits are relatively plastic over ontogeny in both species, possibly caused by behavioural variation within each instar. Additionally, boldness, but not activity and exploration, might aid S. fonscolombii in their northward expansion. The majority of these results were similar at both temperatures and indicate that S. fonscolombii has a higher capacity to tolerate climate change, and their presence might negatively impact the performance of S. vulgatum.
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Gates, Kiza Kristine. "Coexistence between a native (Valvata humeralis) and a non-native (Potamopyrgus antipodarum) gastropod in the Middle Snake River, Idaho: implications for invasive species impact." Diss., Montana State University, 2012. http://etd.lib.montana.edu/etd/2012/gates/GatesK0812.pdf.
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The dominant competitive abilities of many invasive species are frequently assumed to preclude biologically similar native species over time, but there has been little research exploring how interactions between invasive and native species may change with changes in biotic and abiotic conditions. Introduction of the invasive New Zealand mud snail Potamopyrgus antipodarum in the Snake River in the late 1980's raised many concerns for the native gastropods of this region; however, the native gastropod Valvata humeralis has maintained large populations and continued to coexist with P. antipodarum. I investigated the coexistence of P. antipodarum and V. humeralis in the Vista reach of the Middle Snake River. Diet, spatial, and temporal partitioning of V. humeralis were explored in populations that were invaded by P. antipodarum and uninvaded. A field growth experiment was used to measure the net intra- and interspecific effects of V. humeralis and P. antipodarum at varying densities and species proportions. Results of the field growth experiment were compared with field survey data. A laboratory growth experiment and a stoichiometric experiment were used to identify the interaction mechanisms between species. Valvata humeralis juveniles appeared to shift diet in the presence P. antipodarum. There was evidence of spatial partitioning from P. antipodarum by V. humeralis at the among population scale but not the within population or patch scales. The field growth experiment indicated that interspecific net effects of P. antipodarum on V. humeralis changed in direction with increasing P. antipodarum density. Field surveys showed a similar pattern. The laboratory growth experiment indicated that direct interference competition was the negative mechanism of the species interaction and confirmed field experimental results. Stoichiometric analyses suggested that P. antipodarum juveniles require more phosphorus than V. humeralis juveniles, but that stoichiometric facilitation was not likely an interaction mechanism. Facilitated growth of V. humeralis in the presence of P. antipodarum may have been caused by increased access to food and/or P. antipodarum digestive food conditioning. Results suggest that the impact of an invasive species on the native community may be a complex interplay between invader density, native species behavior, invader nutrient use, and environmental conditions. 'Co-authored by Billie. L. Kerans.'
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Poulette, Megan Marie. "ECOSYSTEM IMPACTS OF THE INVASIVE SHRUB LONICERA MAACKII ARE INFLUENCED BY ASSOCIATIONS WITH NATIVE TREE SPECIES." UKnowledge, 2012. http://uknowledge.uky.edu/biology_etds/6.
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Invasive species are significant drivers of global environmental change, altering the stability and functioning of numerous ecosystems. The exotic shrub Lonicera maackii is an aggressive invader throughout much of the eastern United States. While much is known about its population and community impacts, little is known about effects on ecosystem processes.
This dissertation documents changes in ecosystem processes associated with L. maackii growing beneath three native tree species (Fraxinus quadrangulata, Quercus muehlenbergii, Carya ovata) in a savanna in Kentucky. Like many invasive plants, L. maackii litter decomposed and lost nitrogen (N) rapidly, especially in comparison with native tree litter. In comparison to the soils beneath the trees where the exotic shrub was absent, soils beneath L. maackii had a lower bulk density, elevated soil organic matter, C:N, and total soil N and a modified soil microbial community. Inorganic N deposition from spring throughfall was also altered by L. maackii, with higher NO3-N deposition beneath shrubs located beneath the tree canopy relative to canopy locations without L. maackii.
While many exotic plant species have been shown to alter ecosystem processes, their impact is often not uniform. This variability is attributed to among-site differences (soil, climate, plant community): within site variability is often ignored. While many of L. maackii’s alterations to ecosystem processes were uniform across the site, several were dependent upon interactions between the exotic and the native tree species. Litter from L. maackii decomposed and lost N more rapidly under C. ovata than under the other native tree species. Soils beneath L. maackii shrubs located under C. ovata also had a greater fungal:bacterial ratio and a greater abundance of the saprophytic fungal lipid biomarker 18:1ω9c.
These results demonstrate that L. maackii’s impact extends to ecosystem processes and suggests that invasive plants may have variable effects within a given environment depending on their interactions with the dominant native species. Identifying native species or communities that are more vulnerable to alterations of ecosystem function upon invasion may prove useful to land managers and foster a better understanding of the role that community dynamics play in moderating or enhancing invasive species impacts.
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Pagès, Marie. "Partnerships between professionals and amateurs in nature conservation : an examination of motivations and discourses in the management of invasive non-native species." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231663.
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Invasive Non-Native Species (INNS), or Invasive Alien Species, are organisms introduced by humans outside their natural range that have “negative impacts on biodiversity, socio-economy or human health”. Growing awareness of the ecological and socio-economic impacts of INNS has led to a mushrooming of control attempts across the UK. The costs of such environmental management has grown far in excess of the availability of funds to afford control by professionals and led to widespread involvement of volunteers in INNS management and monitoring. This thesis aimed to identify challenges in collaborations between lay people and experts in ecological restoration and to critically examine some of the claims made about the benefits of citizen participation on the sustainability and democratisation of environmental management and on citizen empowerment. Qualitative research methodology was employed to explore in depth motivations, experiences, intentions and views of volunteers and of the organisations that attempt to enrol them in practical conservation work and monitoring activities. We found that caring for nature, the experience of nature and the activities, and social interactions were the three main drivers of volunteering. Importantly, over time, motivations were shaped by the interplay between individual expectations and experiences with the social and ecological context and changed from identifiable personal goals and functions to more complex attachments to the place and the group. Our research also revealed that while some of these key motivations may be recognised by project managers, their description of costeffectiveness, local ownership and empowerment as complementary volunteering goals were often not aligned in practice. Moreover, decision-making may remain largely expert-based, with volunteers not perceiving their knowledge to be valid or a useful contribution to decision-making. Enhancing the sustainability and democratic nature of INNS management requires reflexive practice of citizen engagement that explicitly considers different interests and views but also invites citizens to reflect on their role in the co-production of conservation practice and knowledge.
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Savage, Matthew B. "A NON-NATIVE FOREST INVADER ALTERS FOREST STRUCTURE AND THE ASSOCIATED ARTHROPOD COMMUNITY." UKnowledge, 2017. http://uknowledge.uky.edu/entomology_etds/41.
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The emerald ash borer (EAB, Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) is a non-native wood boring beetle that is causing extensive ash (Fraxinus spp.) mortality in eastern North America, affecting both urban and wildland forests and drastically altering forest structure and composition. As EAB-induced ash mortality progresses, native arthropod associates of ash forests are impacted by the effects of rapid and broad scale tree mortality. These include loss of food source, increased canopy gap formation, alterations in litter inputs causing shifting temperature and moisture regimes on the forest floor, and significant accumulation of coarse woody debris.
I assessed the sub-canopy arthropod community in five forests, all in different stages of the invasion process, from introduction through impact. Additionally, I assessed the ground level arthropod community in a post EAB-invaded forest with 100% mature ash mortality. Arthropod communities were assessed at the ordinal level, and with a focus on coleopterans, they were further classified to families and trophic guilds to analyze abundance, richness, and diversity. Due to their overwhelming abundance, I identified scolytines collected in the post EAB-invaded forest to species to see if the EAB-invasion was part of a greater invasional meltdown. My results indicate that the EAB-invasion in North America is affecting the native coleopteran communities associated with these forests.
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Howard, Simon William. "Effects of trout on galaxiid growth and antipredator behaviour." Thesis, University of Canterbury. Biological Sciences, 2007. http://hdl.handle.net/10092/1438.
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The introduction of trout has been implicated in the declines in native fish fauna in New Zealand and worldwide. Since the introduction of brown (Salmo trutta) and rainbow (Oncorhynchus mykiss) trout to New Zealand in 1867, their distribution has spread and they have been implicated in the fragmentation of native fish distributions, particularly native non-migratory galaxiids. However, in the Upper Waimakariri basin the co-occurrence of trout and galaxiid populations is relatively common, even in streams where trout reach sizes known to be piscivorous. To investigate mechanisms that may regulate trout and galaxiid co-occurrence, I investigated differences in antipredator behaviour and growth rate between stream types with varying levels of trout presence. Using quantitative survey data collected between 1997 and 2006, I found that trout abundance was low and varied annually in frequently disturbed sites compared their high abundance in stable streams. This finding was used to classify streams into three population types, barrier (trout absent), disturbed (trout presence intermittent) and sympatric (constant trout presence). Using this classification, I tested the effects of trout chemical cues on galaxiid activity and refuge use in artificial channels. There were no differences in activity or refuge use between trout odour and there were no effects of population type or galaxiid size during both the day and the night. Using otolith weight-fish length relationships in galaxiids collected from each population type, I found that galaxiid growth rate was higher in disturbed streams than in stable streams either with or without trout. An experiment manipulating trout size and presence, over two months in a natural stream, found galaxiids from treatments without trout grew slower than those with trout. Slow growth rates in galaxiids above trout-migration barriers and in sympatry, combined with low growth rates in treatments without trout suggest that the mechanisms that regulate galaxiid growth are more complex than previously thought.
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Barnett, Jennifer M. "The Impact of Chinese Privet (Ligustrum Sinense) on the Survival and Re-Establishment of Native Plants at the Dallas Floodway Extension." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc862725/.
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Invasive woody shrubs are a problem when they displace native species and threaten habitats, especially those that harbor rare or endangered species. They not only compete with native plants, but also alter habitat and food that many organisms depend upon. Invasive plants undergo a release from their specialist predators in the nonnative range, providing them advantages over native species. Because modes and pathways of how invasive species spread are not fully understood, predicting spread and implementing restoration ecological controls remain inexact. Due to the lack of comparative studies on woody shrubs, especially invasive privets, we understand very little about conditions affecting their invasiveness. A study was conducted near Dallas, Texas to determine if privet has allelopathic properties that influences growth of native plants. Soil nutrients and other analyses were made and compared between field plots supporting privet, plots in which privet has been removed, and plots where privet has not been observed. In some field plots, natives were planted under the three previously mentioned conditions, and their survival and condition were monitored to evaluate effects of privet on their establishment and growth. It was found that Chinese privet did hinder seed germination in red mulberry, soapberry and beautyberry and root formation in beautyberry cuttings. The soil in the sites were found to be normal for bottomland forests that endured two flooding events within one year.
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Berman, Maïa. "Impacts of anthropogenic fires and invasive ants on native ant diversity in New Caledonia : from genes to communities." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20086/document.
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La destruction de l'habitat, les invasions biologiques et leur interaction sont des menaces majeures pour la biodiversité. La Nouvelle-Calédonie est menacée à la fois par des feux d'origine humaine, et par des fourmis invasives : il est important de comprendre leur impact sur ce biotope unique. Pour ce faire, une approche hiérarchique intégrant différents aspects de la biodiversité (composition, structure et fonction) a été adoptée. Les fourmis ont une grande importance écologique, en particulier en milieu tropical, et leur classification en groupes fonctionnels facilite l'interprétation de leur réponse aux perturbations environnementales. Les objectifs de cette étude étaient donc d'évaluer les impacts des feux, des fourmis invasives, et de leur interaction, sur les fourmis natives de Nouvelle-Calédonie, et ce à différentes échelles spatiales (globale, régionale, locale) et temporelles (court et long terme), ainsi qu'à divers niveaux d'organisation biologique (communautés, espèces, gènes). L'étude contribue à une meilleure connaissance de la myrmécofaune calédonienne, en révélant l'absence de fourmis souterraines spécialisées, et en documentant la distribution et composition des communautés de fourmis à l'échelle de l'île, en lien avec l'habitat et les fourmis exotiques. Les mécanismes par lesquels les feux impactent les fourmis natives, y compris en association avec les fourmis invasives, sont révélés. Le feu, en créant les conditions de micro- et macrohabitat favorisées par les fourmis invasives, facilite l'invasion, qui cause ensuite d'avantage de perte de diversité, soit quelques années après un incendie ou dans le contexte de la fragmentation à long terme. L'approche hiérarchique a permis de détecter des réponses contrastées au niveau des espèces et de la génétique, liées à différents traits d'histoire de vie, en plus des réponses mesurées au niveau des communautés. Cette étude souligne l'avantage d'une approche holistique pour adresser des problèmes liés à la biodiversitéHabitat destruction, biological invasions and their interaction are global drivers of biodiversity loss. The New Caledonian hotspot of biodiversity is threatened by both anthropogenic fires and invasive ants: it is important to understand their impacts on its biota. Because biodiversity spans several levels of organisation (from genes to communities) and relates to different attributes (compositional, structural and functional), this thesis takes a hierarchical approach to address this issue. Ants are of great ecological importance, especially in tropical biomes, and their classification into functional groups provides a global framework for analysing their response to disturbance. My aims were therefore to investigate the impacts of anthropogenic fires and invasive ants, and their interaction, on the native New Caledonian ant fauna at different spatial (global, regional, local) and temporal (short and long term) scales, and at different levels of biological organisation (community, species, genes). The study contributes to an improved knowledge of the New Caledonian ants, by revealing the lack of specialised subterranean species, and by investigating island-scale patterns of ant communities, in relation to habitat and invasion. The mechanisms by which fire impacts native ants, either as a standalone process or in association with invasion could be identified. In particular, I show that fire, by creating macro- and microhabitats favoured by invasive ants, facilitates invasion, which then causes further diversity declines, either in the short- (post-burning) or long-term (forest fragmentation). The hierarchical approach used enabled the detection of contrasting trait-derived responses at the species and genetic level, in addition to responses measured at the community level. This study highlights the advantage of a holistic approach to investigating biodiversity-related issues
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Villazon, Kathryn Aubrey. "Methods to restore native plant communities after invasive species removal marl prairie ponds and an abandoned phosphate mine in Florida /." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0041336.
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Jacques, Rochelle R. "Effects of Microstegium vimineum (Trin.) A. Camus (Asian stiltgrass; Poaceae) on native hardwood seedling growth and survival." Ohio : Ohio University, 2007. http://www.ohiolink.edu/etd/view.cgi?ohiou1180715972.
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