Browsing by Subject "Plants"
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Item Open Access Connecting differential responses of native and invasive riparian plants to climate change and environmental alteration.(Ecol Appl, 2015-04) Flanagan, Neal E; Richardson, Curtis J; Ho, MengchiClimate change is predicted to impact river systems in the southeastern United States through alterations of temperature, patterns of precipitation and hydrology. Future climate scenarios for the southeastern United States predict (1) surface water temperatures will warm in concert with air temperature, (2) storm flows will increase and base flows will decrease, and (3) the annual pattern of synchronization between hydroperiod and water temperature will be altered. These alterations are expected to disturb floodplain plant communities, making them more vulnerable to establishment of invasive species. The primary objective of this study is to evaluate whether native and invasive riparian plant assemblages respond differently to alterations of climate and land use. To study the response of riparian wetlands to watershed and climate alterations, we utilized an existing natural experiment imbedded in gradients of temperature and hydrology-found among dammed and undammed rivers. We evaluated a suite of environmental variables related to water temperature, hydrology, watershed disturbance, and edaphic conditions to identify the strongest predictors of native and invasive species abundances. We found that native species abundance is strongly influenced by climate-driven variables such as temperature and hydrology, while invasive species abundance is more strongly influenced by site-specific factors such as land use and soil nutrient availability. The patterns of synchronization between plant phenology, annual hydrographs, and annual water temperature cycles may be key factors sustaining the viability of native riparian plant communities. Our results demonstrate the need to understand the interactions between climate, land use, and nutrient management in maintaining the species diversity of riparian plant communities. Future climate change is likely to result in diminished competitiveness of native plant species, while the competitiveness of invasive species will increase due to anthropogenic watershed disturbance and accelerated nutrient and sediment export.Item Open Access Correlations between physical and chemical defences in plants: tradeoffs, syndromes, or just many different ways to skin a herbivorous cat?(The New phytologist, 2013-04) Moles, Angela T; Peco, Begoña; Wallis, Ian R; Foley, William J; Poore, Alistair GB; Seabloom, Eric W; Vesk, Peter A; Bisigato, Alejandro J; Cella-Pizarro, Lucrecia; Clark, Connie J; Cohen, Philippe S; Cornwell, William K; Edwards, Will; Ejrnaes, Rasmus; Gonzales-Ojeda, Therany; Graae, Bente J; Hay, Gregory; Lumbwe, Fainess C; Magaña-Rodríguez, Benjamín; Moore, Ben D; Peri, Pablo L; Poulsen, John R; Stegen, James C; Veldtman, Ruan; von Zeipel, Hugo; Andrew, Nigel R; Boulter, Sarah L; Borer, Elizabeth T; Cornelissen, Johannes HC; Farji-Brener, Alejandro G; DeGabriel, Jane L; Jurado, Enrique; Kyhn, Line A; Low, Bill; Mulder, Christa PH; Reardon-Smith, Kathryn; Rodríguez-Velázquez, Jorge; De Fortier, An; Zheng, Zheng; Blendinger, Pedro G; Enquist, Brian J; Facelli, Jose M; Knight, Tiffany; Majer, Jonathan D; Martínez-Ramos, Miguel; McQuillan, Peter; Hui, Francis KCMost plant species have a range of traits that deter herbivores. However, understanding of how different defences are related to one another is surprisingly weak. Many authors argue that defence traits trade off against one another, while others argue that they form coordinated defence syndromes. We collected a dataset of unprecedented taxonomic and geographic scope (261 species spanning 80 families, from 75 sites across the globe) to investigate relationships among four chemical and six physical defences. Five of the 45 pairwise correlations between defence traits were significant and three of these were tradeoffs. The relationship between species' overall chemical and physical defence levels was marginally nonsignificant (P = 0.08), and remained nonsignificant after accounting for phylogeny, growth form and abundance. Neither categorical principal component analysis (PCA) nor hierarchical cluster analysis supported the idea that species displayed defence syndromes. Our results do not support arguments for tradeoffs or for coordinated defence syndromes. Rather, plants display a range of combinations of defence traits. We suggest this lack of consistent defence syndromes may be adaptive, resulting from selective pressure to deploy a different combination of defences to coexisting species.Item Open Access Diversity of ageing across the tree of life.(Nature, 2014-01-09) Jones, Owen R; Scheuerlein, Alexander; Salguero-Gómez, Roberto; Camarda, Carlo Giovanni; Schaible, Ralf; Casper, Brenda B; Dahlgren, Johan P; Ehrlén, Johan; García, María B; Menges, Eric S; Quintana-Ascencio, Pedro F; Caswell, Hal; Baudisch, Annette; Vaupel, James WEvolution drives, and is driven by, demography. A genotype moulds its phenotype's age patterns of mortality and fertility in an environment; these two patterns in turn determine the genotype's fitness in that environment. Hence, to understand the evolution of ageing, age patterns of mortality and reproduction need to be compared for species across the tree of life. However, few studies have done so and only for a limited range of taxa. Here we contrast standardized patterns over age for 11 mammals, 12 other vertebrates, 10 invertebrates, 12 vascular plants and a green alga. Although it has been predicted that evolution should inevitably lead to increasing mortality and declining fertility with age after maturity, there is great variation among these species, including increasing, constant, decreasing, humped and bowed trajectories for both long- and short-lived species. This diversity challenges theoreticians to develop broader perspectives on the evolution of ageing and empiricists to study the demography of more species.Item Open Access Ectopic Expression of OsJAZs Alters Plant Defense and Development.(International journal of molecular sciences, 2022-04) Sun, Baolong; Shang, Luyue; Li, Yang; Zhang, Qiang; Chu, Zhaohui; He, Shengyang; Yang, Wei; Ding, XinhuaA key step in jasmonic acid (JA) signaling is the ligand-dependent assembly of a coreceptor complex comprising the F-box protein COI1 and JAZ transcriptional repressors. The assembly of this receptor complex results in proteasome-mediated degradation of JAZ repressors, which in turn bind and repress MYC transcription factors. Many studies on JAZs have been performed in Arabidopsis thaliana, but the function of JAZs in rice is largely unknown. To systematically reveal the function of OsJAZs, in this study, we compared the various phenotypes resulting from 13 OsJAZs via ectopic expression in Arabidopsis thaliana and the phenotypes of 12 AtJAZs overexpression (OE) lines. Phylogenetic analysis showed that the 25 proteins could be divided into three major groups. Yeast two-hybrid (Y2H) assays revealed that most OsJAZ proteins could form homodimers or heterodimers. The statistical results showed that the phenotypes of the OsJAZ OE plants were quite different from those of AtJAZ OE plants in terms of plant growth, development, and immunity. As an example, compared with other JAZ OE plants, OsJAZ11 OE plants exhibited a JA-insensitive phenotype and enhanced resistance to Pst DC3000. The protein stability after JA treatment of OsJAZ11 emphasized the specific function of the protein. This study aimed to explore the commonalities and characteristics of different JAZ proteins functions from a genetic perspective, and to screen genes with disease resistance value. Overall, the results of this study provide insights for further functional analysis of rice JAZ family proteins.Item Open Access Emerging contaminant or an old toxin in disguise? Silver nanoparticle impacts on ecosystems.(Environ Sci Technol, 2014-05-06) Colman, Benjamin P; Espinasse, Benjamin; Richardson, Curtis J; Matson, Cole W; Lowry, Gregory V; Hunt, Dana E; Wiesner, Mark R; Bernhardt, Emily SThe use of antimicrobial silver nanoparticles (AgNPs) in consumer-products is rising. Much of these AgNPs are expected to enter the wastewater stream, with up to 10% of that eventually released as effluent into aquatic ecosystems with unknown ecological consequences. We examined AgNP impacts on aquatic ecosystems by comparing the effects of two AgNP sizes (12 and 49 nm) to ionic silver (Ag(+); added as AgNO3), a historically problematic contaminant with known impacts. Using 19 wetland mesocosms, we added Ag to the 360 L aquatic compartment to reach 2.5 mg Ag L(-1). Silver treatments and two coating controls were done in triplicate, and compared to four replicate controls. All three silver treatments were toxic to aquatic plants, leading to a significant release of dissolved organic carbon and chloride following exposure. Simultaneously, dissolved methane concentrations increased forty-fold relative to controls in all three Ag treatments. Despite dramatic toxicity differences observed in lab studies for these three forms of Ag, our results show surprising convergence in the direction, magnitude, and duration of ecosystem-scale impacts for all Ag treatments. Our results suggest that all forms of Ag changed solute chemistry driving transformations of Ag which then altered Ag impacts.Item Open Access Emerging Technologies to Conserve Biodiversity.(Trends in ecology & evolution, 2015-11) Pimm, Stuart L; Alibhai, Sky; Bergl, Richard; Dehgan, Alex; Giri, Chandra; Jewell, Zoë; Joppa, Lucas; Kays, Roland; Loarie, ScottTechnologies to identify individual animals, follow their movements, identify and locate animal and plant species, and assess the status of their habitats remotely have become better, faster, and cheaper as threats to the survival of species are increasing. New technologies alone do not save species, and new data create new problems. For example, improving technologies alone cannot prevent poaching: solutions require providing appropriate tools to the right people. Habitat loss is another driver: the challenge here is to connect existing sophisticated remote sensing with species occurrence data to predict where species remain. Other challenges include assembling a wider public to crowdsource data, managing the massive quantities of data generated, and developing solutions to rapidly emerging threats.Item Open Access Environmental conditions influence the plant functional diversity effect on potential denitrification.(PLoS One, 2011-02-02) Sutton-Grier, Ariana E; Wright, Justin P; McGill, Bonnie M; Richardson, CurtisGlobal biodiversity loss has prompted research on the relationship between species diversity and ecosystem functioning. Few studies have examined how plant diversity impacts belowground processes; even fewer have examined how varying resource levels can influence the effect of plant diversity on microbial activity. In a field experiment in a restored wetland, we examined the role of plant trait diversity (or functional diversity, (FD)) and its interactions with natural levels of variability of soil properties, on a microbial process, denitrification potential (DNP). We demonstrated that FD significantly affected microbial DNP through its interactions with soil conditions; increasing FD led to increased DNP but mainly at higher levels of soil resources. Our results suggest that the effect of species diversity on ecosystem functioning may depend on environmental factors such as resource availability. Future biodiversity experiments should examine how natural levels of environmental variability impact the importance of biodiversity to ecosystem functioning.Item Open Access Environmental fate and effects of Bacillus thuringiensis (Bt) proteins from transgenic crops: a review.(Journal of agricultural and food chemistry, 2005-06) Clark, BW; Phillips, TA; Coats, JRThis paper reviews the scientific literature addressing the environmental fate and nontarget effects of the Cry protein toxins from Bacillus thuringiensis (Bt), specifically resulting from their expression in transgenic crops. Published literature on analytical methodologies for the detection and quantification of the Cry proteins in environmental matrices is also reviewed, with discussion of the adequacy of the techniques for determining the persistence and mobility of the Bt proteins. In general, assessment of the nontarget effects of Bt protein toxins indicates that there is a low level of hazard to most groups of nontarget organisms, although some investigations are of limited ecological relevance. Some published reports on the persistence of the proteins in soil show short half-lives, whereas others show low-level residues lasting for many months. Improvements in analytical methods will allow a more complete understanding of the fate and significance of Bt proteins in the environment.Item Open Access Estimating the normal background rate of species extinction.(Conservation biology : the journal of the Society for Conservation Biology, 2015-04) De Vos, Jurriaan M; Joppa, Lucas N; Gittleman, John L; Stephens, Patrick R; Pimm, Stuart LA key measure of humanity's global impact is by how much it has increased species extinction rates. Familiar statements are that these are 100-1000 times pre-human or background extinction levels. Estimating recent rates is straightforward, but establishing a background rate for comparison is not. Previous researchers chose an approximate benchmark of 1 extinction per million species per year (E/MSY). We explored disparate lines of evidence that suggest a substantially lower estimate. Fossil data yield direct estimates of extinction rates, but they are temporally coarse, mostly limited to marine hard-bodied taxa, and generally involve genera not species. Based on these data, typical background loss is 0.01 genera per million genera per year. Molecular phylogenies are available for more taxa and ecosystems, but it is debated whether they can be used to estimate separately speciation and extinction rates. We selected data to address known concerns and used them to determine median extinction estimates from statistical distributions of probable values for terrestrial plants and animals. We then created simulations to explore effects of violating model assumptions. Finally, we compiled estimates of diversification-the difference between speciation and extinction rates for different taxa. Median estimates of extinction rates ranged from 0.023 to 0.135 E/MSY. Simulation results suggested over- and under-estimation of extinction from individual phylogenies partially canceled each other out when large sets of phylogenies were analyzed. There was no evidence for recent and widespread pre-human overall declines in diversity. This implies that average extinction rates are less than average diversification rates. Median diversification rates were 0.05-0.2 new species per million species per year. On the basis of these results, we concluded that typical rates of background extinction may be closer to 0.1 E/MSY. Thus, current extinction rates are 1,000 times higher than natural background rates of extinction and future rates are likely to be 10,000 times higher.Item Open Access Evolution of networks and sequences in eukaryotic cell cycle control.(Philos Trans R Soc Lond B Biol Sci, 2011-12-27) Cross, Frederick R; Buchler, Nicolas E; Skotheim, Jan MThe molecular networks regulating the G1-S transition in budding yeast and mammals are strikingly similar in network structure. However, many of the individual proteins performing similar network roles appear to have unrelated amino acid sequences, suggesting either extremely rapid sequence evolution, or true polyphyly of proteins carrying out identical network roles. A yeast/mammal comparison suggests that network topology, and its associated dynamic properties, rather than regulatory proteins themselves may be the most important elements conserved through evolution. However, recent deep phylogenetic studies show that fungal and animal lineages are relatively closely related in the opisthokont branch of eukaryotes. The presence in plants of cell cycle regulators such as Rb, E2F and cyclins A and D, that appear lost in yeast, suggests cell cycle control in the last common ancestor of the eukaryotes was implemented with this set of regulatory proteins. Forward genetics in non-opisthokonts, such as plants or their green algal relatives, will provide direct information on cell cycle control in these organisms, and may elucidate the potentially more complex cell cycle control network of the last common eukaryotic ancestor.Item Open Access Horsetails and ferns are a monophyletic group and the closest living relatives to seed plants.(Nature, 2001-02) Pryer, KM; Schneider, H; Smith, AR; Cranfill, R; Wolf, PG; Hunt, JS; Sipes, SDMost of the 470-million-year history of plants on land belongs to bryophytes, pteridophytes and gymnosperms, which eventually yielded to the ecological dominance by angiosperms 90 Myr ago. Our knowledge of angiosperm phylogeny, particularly the branching order of the earliest lineages, has recently been increased by the concurrence of multigene sequence analyses. However, reconstructing relationships for all the main lineages of vascular plants that diverged since the Devonian period has remained a challenge. Here we report phylogenetic analyses of combined data--from morphology and from four genes--for 35 representatives from all the main lineages of land plants. We show that there are three monophyletic groups of extant vascular plants: (1) lycophytes, (2) seed plants and (3) a clade including equisetophytes (horsetails), psilotophytes (whisk ferns) and all eusporangiate and leptosporangiate ferns. Our maximum-likelihood analysis shows unambiguously that horsetails and ferns together are the closest relatives to seed plants. This refutes the prevailing view that horsetails and ferns are transitional evolutionary grades between bryophytes and seed plants, and has important implications for our understanding of the development and evolution of plants.Item Open Access Impacts of shrub encroachment on ecosystem structure and functioning: towards a global synthesis(Ecology Letters, 2011) Eldridge; DJ; Bowker, MA; Maestre, FT; Roger, E; REYNOLDS, JF; Whitford, WGEncroachment of woody plants into grasslands has generated considerable interest among ecologists. Syntheses of encroachment effects on ecosystem processes have been limited in extent and confined largely to pastoral land uses or particular geographical regions. We used univariate analyses, meta-analysis and structural equation modelling to test the propositions that (1) shrub encroachment does not necessarily lead to declines in ecosystem functions and (2) shrub traits influence the functional outcome of encroachment. Analyses of 43 ecosystem attributes from 244 case studies worldwide showed that some attributes consistently increased with encroachment (e.g. soil C, N), and others declined (e.g. grass cover, pH), but most exhibited variable responses. Traits of shrubs were associated with significant, though weak, structural and functional outcomes of encroachment. Our review revealed that encroachment had mixed effects on ecosystem structure and functioning at global scales, and that shrub traits influence the functional outcome of encroachment. Thus, a simple designation of encroachment as a process leading to functionally, structurally or contextually degraded ecosystems is not supported by a critical analysis of existing literature. Our results highlight that the commonly established link between shrub encroachment and degradation is not universal.Item Open Access Information processing without brains--the power of intercellular regulators in plants.(Development, 2010-04) Busch, Wolfgang; Benfey, Philip NPlants exhibit different developmental strategies than animals; these are characterized by a tight linkage between environmental conditions and development. As plants have neither specialized sensory organs nor a nervous system, intercellular regulators are essential for their development. Recently, major advances have been made in understanding how intercellular regulation is achieved in plants on a molecular level. Plants use a variety of molecules for intercellular regulation: hormones are used as systemic signals that are interpreted at the individual-cell level; receptor peptide-ligand systems regulate local homeostasis; moving transcriptional regulators act in a switch-like manner over small and large distances. Together, these mechanisms coherently coordinate developmental decisions with resource allocation and growth.Item Open Access Long-term transformation and fate of manufactured ag nanoparticles in a simulated large scale freshwater emergent wetland.(Environ Sci Technol, 2012-07-03) Lowry, GV; Espinasse, BP; Badireddy, AR; Richardson, CJ; Reinsch, BC; Bryant, LD; Bone, AJ; Deonarine, A; Chae, S; Therezien, M; Colman, BP; Hsu Kim, H; Bernhardt, ES; Matson, CW; Wiesner, MRTransformations and long-term fate of engineered nanomaterials must be measured in realistic complex natural systems to accurately assess the risks that they may pose. Here, we determine the long-term behavior of poly(vinylpyrrolidone)-coated silver nanoparticles (AgNPs) in freshwater mesocosms simulating an emergent wetland environment. AgNPs were either applied to the water column or to the terrestrial soils. The distribution of silver among water, solids, and biota, and Ag speciation in soils and sediment was determined 18 months after dosing. Most (70 wt %) of the added Ag resided in the soils and sediments, and largely remained in the compartment in which they were dosed. However, some movement between soil and sediment was observed. Movement of AgNPs from terrestrial soils to sediments was more facile than from sediments to soils, suggesting that erosion and runoff is a potential pathway for AgNPs to enter waterways. The AgNPs in terrestrial soils were transformed to Ag(2)S (~52%), whereas AgNPs in the subaquatic sediment were present as Ag(2)S (55%) and Ag-sulfhydryl compounds (27%). Despite significant sulfidation of the AgNPs, a fraction of the added Ag resided in the terrestrial plant biomass (~3 wt % for the terrestrially dosed mesocosm), and relatively high body burdens of Ag (0.5-3.3 μg Ag/g wet weight) were found in mosquito fish and chironomids in both mesocosms. Thus, Ag from the NPs remained bioavailable even after partial sulfidation and when water column total Ag concentrations are low (<0.002 mg/L).Item Open Access Low concentrations of silver nanoparticles in biosolids cause adverse ecosystem responses under realistic field scenario.(PLoS One, 2013) Colman, Benjamin P; Arnaout, Christina L; Anciaux, Sarah; Gunsch, Claudia K; Hochella, Michael F; Kim, Bojeong; Lowry, Gregory V; McGill, Bonnie M; Reinsch, Brian C; Richardson, Curtis J; Unrine, Jason M; Wright, Justin P; Yin, Liyan; Bernhardt, Emily SA large fraction of engineered nanomaterials in consumer and commercial products will reach natural ecosystems. To date, research on the biological impacts of environmental nanomaterial exposures has largely focused on high-concentration exposures in mechanistic lab studies with single strains of model organisms. These results are difficult to extrapolate to ecosystems, where exposures will likely be at low-concentrations and which are inhabited by a diversity of organisms. Here we show adverse responses of plants and microorganisms in a replicated long-term terrestrial mesocosm field experiment following a single low dose of silver nanoparticles (0.14 mg Ag kg(-1) soil) applied via a likely route of exposure, sewage biosolid application. While total aboveground plant biomass did not differ between treatments receiving biosolids, one plant species, Microstegium vimeneum, had 32 % less biomass in the Slurry+AgNP treatment relative to the Slurry only treatment. Microorganisms were also affected by AgNP treatment, which gave a significantly different community composition of bacteria in the Slurry+AgNPs as opposed to the Slurry treatment one day after addition as analyzed by T-RFLP analysis of 16S-rRNA genes. After eight days, N2O flux was 4.5 fold higher in the Slurry+AgNPs treatment than the Slurry treatment. After fifty days, community composition and N2O flux of the Slurry+AgNPs treatment converged with the Slurry. However, the soil microbial extracellular enzymes leucine amino peptidase and phosphatase had 52 and 27% lower activities, respectively, while microbial biomass was 35% lower than the Slurry. We also show that the magnitude of these responses was in all cases as large as or larger than the positive control, AgNO3, added at 4-fold the Ag concentration of the silver nanoparticles.Item Open Access Molecular phylogenetic studies in nyctaginaceae: patterns of diversification in arid North America(2007-05-04T17:36:36Z) Douglas, Norman AlanThe Four O'clock Family (Nyctaginaceae) has a number of genera with unusual morphological and ecological characters, several of which appear to have a "tendency" to evolve repeatedly in Nyctaginaceae. I present a molecular phylogeny for the Nyctaginaceae, consider taxonomic implications, biogeographic patterns, and the evolution of cleistogamy and gypsophily. These characters have each evolved multiple times in the xeric-adapted genera of the family. Further progress towards understanding these phenomena requires specific investigation of the ecology of pollination and gypsum tolerance. In the genus Boerhavia, an intensively sampled phylogeny based on internal transcribed spacer (ITS) and nitrate reductase (NIA) sequences provides new insights into relationships among species in the genus, and identifies a clade of annual species centered in the Sonoran Desert. Phylogeographic patterns are present in the genus that may reflect both relatively ancient vicariant events as well as the post-Pleistocene expansion of the Sonoran Desert. Many species in this group are found to be genetically cohesive, however two annual species complexes are found which species were nonmonophyletic. Since several mechanisms can potentially lead to the finding of nonmonophyletic species, Amplified Fragment Length Polymorphisms (AFLPs) were used to examine the structure of genetic variation in the two complexes. These data show that in these two groups, different evolutionary mechanisms are needed to explain the distribution of genetic diversity within and among populations. A complex comprised of Boerhavia spicata and B. xanti shows little evidence of genetic divergence between the species in Sonora, a pattern which may indicate recent contact between two very closely related forms. In contrast, high genetic structure between populations is found in the other complex, which contains the species with umbellate inflorescences. This complex includes several nominal species with highly restricted distributions, whose evolution may have been facilitated by low gene flow among populations. Little evidence was found for associations of inbreeding within populations, and floral traits which might be expected to influence outcrossing rates.Item Open Access Non-neutral vegetation dynamics.(PLoS One, 2006-12-20) Marani, M; Zillio, T; Belluco, E; Silvestri, S; Maritan, AThe neutral theory of biodiversity constitutes a reference null hypothesis for the interpretation of ecosystem dynamics and produces relatively simple analytical descriptions of basic system properties, which can be easily compared to observations. On the contrary, investigations in non-neutral dynamics have in the past been limited by the complexity arising from heterogeneous demographic behaviours and by the relative paucity of detailed observations of the spatial distribution of species diversity (beta-diversity): These circumstances prevented the development and testing of explicit non-neutral mathematical descriptions linking competitive strategies and observable ecosystem properties. Here we introduce an exact non-neutral model of vegetation dynamics, based on cloning and seed dispersal, which yields closed-form characterizations of beta-diversity. The predictions of the non-neutral model are validated using new high-resolution remote-sensing observations of salt-marsh vegetation in the Venice Lagoon (Italy). Model expressions of beta-diversity show a remarkable agreement with observed distributions within the wide observational range of scales explored (5 x 10(-1) m divided by 10(3) m). We also consider a neutral version of the model and find its predictions to be in agreement with the more limited characterization of beta-diversity typical of the neutral theory (based on the likelihood that two sites be conspecific or heterospecific, irrespective of the species). However, such an agreement proves to be misleading as the recruitment rates by propagules and by seed dispersal assumed by the neutral model do not reflect known species characteristics and correspond to averages of those obtained under the more general non-neutral hypothesis. We conclude that non-neutral beta-diversity characterizations are required to describe ecosystem dynamics in the presence of species-dependent properties and to successfully relate the observed patterns to the underlying processes.Item Open Access Plant species' origin predicts dominance and response to nutrient enrichment and herbivores in global grasslands.(Nat Commun, 2015-07-15) Seabloom, Eric W; Borer, Elizabeth T; Buckley, Yvonne M; Cleland, Elsa E; Davies, Kendi F; Firn, Jennifer; Harpole, W Stanley; Hautier, Yann; Lind, Eric M; MacDougall, Andrew S; Orrock, John L; Prober, Suzanne M; Adler, Peter B; Anderson, T Michael; Bakker, Jonathan D; Biederman, Lori A; Blumenthal, Dana M; Brown, Cynthia S; Brudvig, Lars A; Cadotte, Marc; Chu, Chengjin; Cottingham, Kathryn L; Crawley, Michael J; Damschen, Ellen I; Dantonio, Carla M; DeCrappeo, Nicole M; Du, Guozhen; Fay, Philip A; Frater, Paul; Gruner, Daniel S; Hagenah, Nicole; Hector, Andy; Hillebrand, Helmut; Hofmockel, Kirsten S; Humphries, Hope C; Jin, Virginia L; Kay, Adam; Kirkman, Kevin P; Klein, Julia A; Knops, Johannes MH; La Pierre, Kimberly J; Ladwig, Laura; Lambrinos, John G; Li, Qi; Li, Wei; Marushia, Robin; McCulley, Rebecca L; Melbourne, Brett A; Mitchell, Charles E; Moore, Joslin L; Morgan, John; Mortensen, Brent; O'Halloran, Lydia R; Pyke, David A; Risch, Anita C; Sankaran, Mahesh; Schuetz, Martin; Simonsen, Anna; Smith, Melinda D; Stevens, Carly J; Sullivan, Lauren; Wolkovich, Elizabeth; Wragg, Peter D; Wright, Justin; Yang, LouieExotic species dominate many communities; however the functional significance of species' biogeographic origin remains highly contentious. This debate is fuelled in part by the lack of globally replicated, systematic data assessing the relationship between species provenance, function and response to perturbations. We examined the abundance of native and exotic plant species at 64 grasslands in 13 countries, and at a subset of the sites we experimentally tested native and exotic species responses to two fundamental drivers of invasion, mineral nutrient supplies and vertebrate herbivory. Exotic species are six times more likely to dominate communities than native species. Furthermore, while experimental nutrient addition increases the cover and richness of exotic species, nutrients decrease native diversity and cover. Native and exotic species also differ in their response to vertebrate consumer exclusion. These results suggest that species origin has functional significance, and that eutrophication will lead to increased exotic dominance in grasslands.Item Open Access Solution NMR studies of the plant peptide hormone CEP inform function.(FEBS letters, 2013-12) Bobay, Benjamin G; DiGennaro, Peter; Scholl, Elizabeth; Imin, Nijat; Djordjevic, Michael A; Mck Bird, DavidThe C-terminally Encoded Peptide (CEP) family of regulatory peptides controls root development in vascular plants. Here, we present the first NMR structures of CEP. We show that root-knot nematode (RKN: Meloidogyne spp.) also encodes CEP, presumably to mimic plant CEP as part of their stereotypic, parasitic interaction with vascular plants. Molecular dynamics simulations of plant- and nematode-encoded CEP displaying known posttranslational modifications (PTM) provided insight into the structural effects of PTM and the conformational plasticity and rigidity of CEP. Potential mechanisms of action are discussed with respect to the structure and sampling of conformational space.Item Open Access Subacute effects of transgenic Cry1ab Bacillus thuringiensis corn litter on the isopods Trachelipus rathkii and Armadillidium nasatum.(Environmental toxicology and chemistry / SETAC, 2006-10) Clark, BW; Prihoda, KR; Coats, JRLaboratory studies were conducted to investigate the subacute effects of transgenic Cry1Ab corn leaf material containing Bacillus thuringiensis (Bt) protein on the terrestrial isopods Trachelipus rathkii and Armadillidium nasatum. Survival and growth were measured for eight weeks in isopods fed leaf material of two Bt11 corn varieties, two Monsanto 810 (Mon810) corn varieties, and the isolines of each. Total lipid and protein content of the organisms was measured to examine effects on energetic reserves. Armadillidium nasatum individuals in all treatments responded similarly. For T. rathkii, no statistically significant effect of Bt was observed, but statistical differences were observed in growth between hybrids. Protein and sugar content of the food were found to be correlated with the differences in growth for T. rathkii. Total protein content was higher in T. rathkii and A. nasatum fed material with higher protein and sugar content. A trend toward less growth in T. rathkii on Bt corn varieties versus their isolines triggered a concentration-response assay with purified Cry1Ab protein. No adverse effects of purified Bt protein were observed. These results indicate that little hazard to T. rathkii and A. nasatum from Bt corn leaf material from these hybrids exists. However, nutritional differences in corn hybrids contributed to differences in isopod growth.