Browsing by Subject "community assembly"

Now showing 1 - 4 of 4
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    Functional diversity of fungal symbiont communities and the impact of biotic and abiotic factors on their composition and assembly
    (2023-09) NDINGA MUNIANIA, Cedric
    Plants harbor tremendously diverse microbial symbiont communities (“the microbiome”) that affect the host fitness and response to environmental changes. Despite their importance, less attention has been given to the response of microbial symbionts to environmental difference, the understanding of which is crucial if we are to use these important organisms for plant conservation and restoration under future stressful conditions. Because microbial symbionts deal with environments at two different scales: the environment inside the host plant and the wider environments outside of the host, understanding the response of these organisms to changing environments requires understanding of the interplay of biotic and abiotic factors on communities. Hence, focusing on dominant members of the plant microbiomes, the fungal endophytes, the main goal of this research was to investigate how the ecological context affect microbial symbiont community structure and assembly. To do that, first, I investigated patterns of carbon resource use and growth of fungal endophytes associated with the prairie grass, Andropogon gerardii, to better understand the processes generating and maintaining functional diversity in this key group of plant symbionts. I found that fungal endophyte communities are comprised of phylogenetically distinct assemblages of slow- and fast-growing fungi that differ in their use and growth on differing carbon substrates. Importantly result revealed that traits characterizing fungi in these assemblages originate from both ancient diversification and ongoing evolutionary processes. Then, to understand how differing deterministic and stochastic processes may contribute to the assembly the fungal symbionts, and the variation of these processes across site environments, spatial scale and time, I sampled roots of the widespread prairie grass, little bluestem (Schizachyrium scoparium) across a 700 km gradient of mean annual precipitation (MAP) and over a span of two years. I used Illumina sequencing of the fungal barcode rDNA (ITS2) to characterize the diversity and composition of fungal communities and employed a community phylogenetic framework to infer the relative contributions of deterministic and stochastic assembly processes. I found that spatial distance and MAP differences among sites significantly affect fungal diversity and community composition. Despite these difference in composition, results revealed that deterministic and stochastic processes exhibit comparable contributions to community assembly across site environments, and that the importance of stochastic processes increases relative to deterministic processes at smaller spatial scales. Interestingly, comparing among years, I found that the composition of fungal communities of historically drier sites tends to shift with interannual differences in weather whereas that of communities in historically wetter environments remain stable, suggesting an importance of past weather on symbiont communities’ response to environmental changes. Lastly, I compared the root and foliar endophytes communities of little bluestem with those of the cultivated crop, corn (Zea mays), to gain insight into the impacts of agriculture on microbial symbiont community diversity and composition. Using Illumina sequencing (ITS2), I characterized root and foliar communities from the two hosts at five locations across a gradient in MAP spanning over 450 km. Results showed that across each sampled location, the composition and diversity of endophyte communities differ between little bluestem and corn, but the magnitude and direction of differences depend on the tissue sampled (roots or leaves) and the site. Collectively these three studies demonstrate that diversity and composition of microbial symbiont communities reflect outcomes of both historical and contemporary process and environmental conditions. Importantly, this study suggests that the composition and diversity of fungal communities will likely shift in response to anthropogenic climate change, but the magnitude and direction of these shifts will depend on the interplay between many biotic and abiotic factors.
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    Fungal Endophytes of Pacific Northwest Beachgrasses Dataset
    (2015-08-26) David, Aaron S; Seabloom, Eric W; May, Georgiana; david250@umn.edu; David, Aaron S
    Leaf and root endophytes sampled from 3 species of grass (Elymus mollis, Ammophila arenaria, and Ammophila breviligulata) and 3 dune locations (front, crest, back) at 5 sites in the Oregon and Washington, USA in Aug-Sept 2011.
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    A global method for calculating plant CSR ecological strategies applied across biomes world‐wide
    (Wiley, 2017) Pierce, Simon; Negreiros, Daniel; Cerabolini, Bruno E. L.; Kattge, Jens; Díaz, Sandra; Kleyer, Michael; Shipley, Bill; Wright, Stuart Joseph; Soudzilovskaia, Nadejda A; Onipchenko, Vladimir G.; van Bodegom, Peter M; Frenette-Dussault, Cedric; Weiher, Evan; Pinho, Bruno X; Cornelissen, Johannes H. C.; Grime, John Philip; Thompson, Ken; Hunt, Roderick; Wilson, Peter J,; Buffa, Gabriella; Nyakunga, Oliver C; Reich, Peter B; Caccianiga, Marco; Mangili, Federico; Ceriani, Roberta M; Luzzaro, Alessandra; Brusa, Guido; Siefert, Andrew; Barbosa, Newton P. U.; Chapin, Francis Stuart, III; Cornwell, William K; Fang, Jingyun; Fernandes, Geraldo Wilson; Garnier, Eric; Le Stradic, Soizig; Peñuelas, Josep; Melo, Felipe P. L.; Slaviero, Antonio; Tabarelli, Marcelo; Tampucci, Duccio
    Competitor, stress-tolerator, ruderal (CSR) theory is a prominent plant functional strategy scheme previously applied to local floras. Globally, the wide geographic and phylogenetic coverage of available values of leaf area (LA), leaf dry matter content (LDMC) and specific leaf area (SLA) (representing, respectively, interspecific variation in plant size and conservative vs. acquisitive resource economics) promises the general application of CSR strategies across biomes, including the tropical forests hosting a large proportion of Earth's diversity. We used trait variation for 3068 tracheophytes (representing 198 families, six continents and 14 biomes) to create a globally calibrated CSR strategy calculator tool and investigate strategy–environment relationships across biomes world-wide. Due to disparity in trait availability globally, co-inertia analysis was used to check correspondence between a ‘wide geographic coverage, few traits’ data set and a ‘restricted coverage, many traits’ subset of 371 species for which 14 whole-plant, flowering, seed and leaf traits (including leaf nitrogen content) were available. CSR strategy/environment relationships within biomes were investigated using fourth-corner and RLQ analyses to determine strategy/climate specializations. Strong, significant concordance (RV = 0·597; P < 0·0001) was evident between the 14 trait multivariate space and when only LA, LDMC and SLA were used. Biomes such as tropical moist broadleaf forests exhibited strategy convergence (i.e. clustered around a CS/CSR median; C:S:R = 43:42:15%), with CS-selection associated with warm, stable situations (lesser temperature seasonality), with greater annual precipitation and potential evapotranspiration. Other biomes were characterized by strategy divergence: for example, deserts varied between xeromorphic perennials such as Larrea divaricata, classified as S-selected (C:S:R = 1:99:0%) and broadly R-selected annual herbs (e.g. Claytonia perfoliata; R/CR-selected; C:S:R = 21:0:79%). Strategy convergence was evident for several growth habits (e.g. trees) but not others (forbs). The CSR strategies of vascular plants can now be compared quantitatively within and between biomes at the global scale. Through known linkages between underlying leaf traits and growth rates, herbivory and decomposition rates, this method and the strategy–environment relationships it elucidates will help to predict which kinds of species may assemble in response to changes in biogeochemical cycles, climate and land use.
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    Leaf-level trade-offs between drought avoidance and desiccation recovery drive elevation stratification in arid oaks: site environmental data, individual tree stem and leaf physiological data, and analyses
    (2018-02-14) Fallon, Beth; Cavender-Bares, Jeannine; eafallon@umn.edu; Fallon, Beth
    This dataset and RStudio project includes all processed data, most raw data, and R scripts needed for analysis and figure construction included in the manuscript Fallon and J. Cavender-Bares 2018 (Fallon B. and J. Cavender-Bares. 2018. Leaf-level trade-offs between drought avoidance and desiccation recovery drive elevation stratification in arid oaks. Ecosphere. in press). We investigated whether oak species in the Chiricahua Mountains were 1) elevationally stratified, 2) whether that stratification was correlated with temperature minima, maxima, and water availability, 3) if physiological tolerances to freezing or drought stress correlated with elevation ranges, and 4) if traits important to local (elevation) distributions were correlated with climatic values of the wider species ranges. Data were collected at field sites from wild, adult trees in the Chiricahua Mountains, Arizona, USA from 2014-2015.This research was done with funding to B. Fallon from the Southwestern Research Station (SWRS, American Museum of Natural History), the University of Minnesota Charles J. Brand, Carolyn Crosby, and Dayton Bell Fellowships, and the Department of Plant and Microbial Biology. Additional funding was provided by NSF Award 1146380 (J. Cavender-Bares PI). We performed all data collection under permit with the Coronado National Forest, Douglas Ranger District, managed by the United States Forest Service (USDA).