Research

Check out the pubs page for the latest projects + some selected projects below

Phylogeny and Evolution in Asteraceae 

Studies of genomic and evolutionary mechanisms that have driven the success of Asteraceae have been hampered by the lack of a well-resolved phylogeny. Mandel et al. (2019) used a phylogenomic framework to fully resolve the Asteraceae backbone. This work supported a late Cretaceous origin followed by explosive diversifications that resulted in the family’s 25,000+ extant species. Ongoing work explores how large-scale gene duplications have influenced diversification in the family. Using 1KP transcriptome data and new transcriptomes from the most undersequenced members of the family (tribes Barnadesieae, Nassauvieae, and Mutisieae), we have identified novel genome duplication events allowing us to explore their role in the early evolution of the family. A unique feature of the phylogenomic tools we use in the lab is their ability to resolve relationships at multiple taxonomic levels, e.g., within tribes or genera. We have studied the evolutionary history of large groups of taxa, “The Fab 5”, five tribes that together comprise more than 10,000 species, or within notoriously complex genera like Packera which is wrought with hybridization and polyploidy.

Asteraceae Comparative Genomics

Rapid and recent advances in genomic technologies have set the stage for asking powerful questions about the origin of new traits. By integrating approaches across comparative genomics and developmental genetics, we can unravel the roles of genome evolution and changes in gene function in generating the biological diversity observed today. To advance evolutionary studies in Asteraceae/Asterales for which genomic resources are lagging, we are generating chromosome-resolved reference genomes using the latest technologies. For example, the addition of Hi-C to our PacBio data dramatically improved draft assemblies and has resulted in a high-quality reference genome for Centrapalus pauciflorus (Vernonieae). We are using a similar approach to sequence and assemble other Asteraceae and related taxa genomes.

Conservation genetics in the endangered whorled sunflower 

The federally endangered whorled sunflower, Helianthus verticillatus Small (Asteraceae), is known only from a handful of populations in the southeastern United States (including small populations in Alabama, Georgia, Mississippi, Tennessee, and Virginia). Recent field and laboratory work aimed at studying this species has revealed greater levels of morphological and genetic diversity than were previously known. Understanding the extent and partitioning of this diversity across populations can inform recovery planning and actions through a better understanding of the taxonomy and potential for successful reintroduction strategies.

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