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Research Interests What is Ecological Genomics? The emerging field of Ecological Genomics seeks to understand the genetic mechanisms underlying responses of organisms to their natural environments. This is being achieved through the application of functional genomic approaches to identify and characterize genes with ecological and evolutionary relevance. By its very nature, ecological genomics is an interdisciplinary field, requiring a multidisciplinary approach that combines field studies with laboratory experiments with in ecologically relevant framework. Thus, while traditionally, ecological and laboratory-based genetic/genomic studies have occupied different areas of biological investigation, Ecological Genomics seeks to integrate these disciplines by using genomic approaches in an ecological context. Big Bluestem—The New Emerging Ecological Model Ecological Genomics in the Johnson Lab focuses on the genetic, molecular and ecological mechanisms involved in adaptation of the prairie grass big bluestem Andropogon gerardii to diverse and changing climates of the Great Plains. This warm season C4 grass has a widespread distribution, extending from the east coast of North America to the Great Plains where it covers vast areas of the prairie landscape and represents as much as 80% of the plant biomass, until petering out at the limit of its distribution in western KS and eastern Colorado. Big bluestem is a long-lived perennial that is widely used in prairie restorations. In 2007 alone, over 800,000 acres just in KS were restored to tall grass species with big bluestem one of the most abundant. Among natural populations, big bluestem shows a striking cline in morphology and physiology in drought adaptation over the 3-fold difference in annual precipitation across the Great Plains (1200 mm/yr in Illinois to 400 mm/r in W KS). The overall objective of the Johnson Lab is to uncover the genetic and molecular basis for the sharp ecotypic variation across the Great Plains. Our lab uses approaches such as gene expression analysis using cross-species hybridization with the maize oligonucleotide array and now 454 sequencing of cDNA libraries, and identification of candidate genes that may be important to drought response or other environmental changes. We complement the genetic work with experimental manipulations and reciprocal garden studies in the field and use the full suite of phenotypic characterizations i.e., physiological measures such as chlorophyll florescence, water use efficiency, photosynthetic rates, and morphological parameters such as specific leaf area, leaf thickness, relatively growth rates, leaf area and biomass, and root:shoot.) We also use a comparative approach by investigating big bluestem’s drought adapted sister species sand bluestem A. halli. Our ultimate goal is to discover how the ecologically dominant big bluestem tall grass can adjust to current sharp precipitation gradients and make predictions about its ability to respond to future and increasingly novel climates. This work also has conservation implications as it will help to inform land managers about the importance of using local ecotypes in prairie restorations and the response of those ecotypes to predicted climate change.
Current Ecological Genomics Projects
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