THE DUVALL LAB AT NIU

The evolutionary history of plants is fascinating and complex. Hybridizations, genome duplications, and other cryptic processes all contribute to this history. We use the contemporary tools of genome-scale analyses in our studies of plant evolution. Our primary study system is the grass family (Poaceae), which has an estimated 12,075 species. There are three major areas of research in the Duvall lab:

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Plastome phylogenomics. Phylogenomics of plastid genomes (plastomes) is the phylogenetic analysis of complete plastid chromosomes. My lab group has sequenced and assembled over 350 plastomes. Complete plastome matrices of coding and noncoding sequences maximize phylogenetic information so that most branch points in the evolutionary trees produced by analysis of these matrices are maximally supported.

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Divergence estimation analysis. This research ties speciation events to paleoclimatic and phytogeographical events. The use of plastomes to estimate divergences leverages increased phylogenetically informative characters and well-supported phylogenomic relationships to increase the accuracy of divergence estimates. These estimates are then interpreted in the context of documented paleoclimatic shifts and tectonic or other events that can alter plant distributions.

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Mutation analysis. With full plastomes in hand, complete characterizations of specific types of mutations (inversions, tandem repeat "indels", recombination mutations, etc.) can be performed for determination of frequencies of each class of mutation.  Microstructural mutations (MCM) can be distinguished from rare genomic changes (RGC).  MCM and RGC have different causal mechanisms, occur at different rates, and exhibit different levels of homoplasy. These events can be tied to specific branch points in evolutionary trees to mark the genomic changes that accompanied evolutionary divergences.