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Methods highlight: Coupling isolates and whole-community 'omics: We employ both culturing and metagenomics techniques, and find the combination of the two effective for probing hypotheses and relationships between physiology, diversity, and function. We have currently developed a high throughput assay for assessing single-isolate desiccation tolerance and population dynamics under drying-rewetting, providing information on physiological strategies for tolerating moisture fluctuation that we can then link to metagenomic or metabolomics data in the whole-community.
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pMicrobes disperse long distances and in great abundances in precipitation, air, and through hosts. Recently, as Baas-Becking’s hypothesis that ‘everything is everywhere and the environment selects’ is challenged by empirical observations, dispersal has received greater recognition as a process shaping microbial community composition. However, the specifics are still unclear. How much does dispersal matter, compared to other things like species filtering? What determines how invadable a community is? How do different aspects of dispersal like rate and colonizer taxonomy and traits affect extant communities?
We recently addressed how dispersal interacts with selection to alter stochasticity in microbial community composition (see Evans et al. 2016, ISMEJ). In the Evans lab, we are now exploring dispersal and colonization in microbial communities in two ways. First, we are characterizing the composition of dispersing communities in air, rain, and fog in two systems, and quantifying the effect of this ‘input’ on soil (or litter) community dynamics and function. Second, graduate student Heather Kittredge (in collaboration with lab manager Kevin Dougherty) is asking how colonizing microorganisms, and specifically their genetic material, move through extant communities through replication and horizontal gene transfer. |
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Methods highlight: individual-based models. We have used models to study both microbial assembly and microbial linkages to ecosystem function. The movie to the left shows a simulation of microbial cells on a soil micro-grid (1 square milimeter!). Different colors represent different microbial functional groups (e.g. cheaters). Individuals compete and are filtered on the grid over time. We used this model to study the role of microbial physiology - and community composition - in drying-rewetting pulses (Evans et al. 2015) with Tina Kaiser at the International Institute of Applied Systems Analysis.
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Methods highlight: stable isotopes. An exciting aspect of this project is the use of isotopes to study plant-microbe interactions. We are developing a pulse-chase method using 13CO2 labeling to quantify rates of root exudation in switchgrass, and also using stable isotope probing (SIP) to characterize which microbes use which C and N compounds.
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