Combining Big Data and Plant Collections to Understand Invasiveness
A major interest of the Sigel lab is utilizing natural history specimens in novel ways to address evolutionary questions, often with important management and societal implications. As part of the Consortium for Plant Invasion Genomics (CPING; www.invasiongenomics.com), we are combining contemporary collections and historical herbarium specimens to better understand the spatial and temporal patterns and processes that underlie plant invasions. Using cutting edge phylogenomic, comparative genomic, and population genomics techniques, we focus on five focal invasive plant species to assess the role of colonization dynamics (i.e., the number, location, timing, and genetic diversity of introductions), hybridization with local species or between geographically disparate populations, and adaptation within the invasive range on the success of historic and recent plant invasions.
Leading the work on Salvinia molesta, a clonally-reproducing aquatic fern listed among the world’s worst 100 invasive plants, the Sigel lab has collected 100’s of herbarium and contemporary samples to address three main questions.
1) What is the genomic composition of giant salvinia and does it result from multiple origins?
2) Is genetic variation in clonal invasive populations of giant salvinia in the NGMCR due to multiple introductions from genetically variable native populations and/or somatic mutation following introduction?
3) Do patterns of epigenetic variation in giant salvinia correspond to patterns of genetic variation?
Our initial findings indicate that S. molesta is an allopolyploid comprising multiple-independently derived lineages formed by repeated hybridization events between two previously undetected parent species. Despite reproducing clonally, S. molesta exhibits substantial genotypic diversity in its invasive range, likely reflecting multiple colonization events from Brazilian source populations (Holt et al., in review, Biological Invasions). In collaboration with Dr. Brittany Sutherland of George Mason University we are adopting a hyRAD approach to better characterize population-level genetic diversity in the southeastern United States and test for the possibility of admixture among populations.
RESEARCH ON SALVINIA SUPPORTED BY THE LOUISIANA BOARD OF REGENTS, NSF AWARD #1920858, AND THE CONSORTIUM FOR PLANT INVASION GENOMICS. LEARN MORE AT INVASIONGENOMICS.COM
Salvinia molesta a. Infestation on Lake Bistineau (image: LSU AgCenter). b. clonal ramete (image: commons.wikimedia.org ) c. characteristic egg-beater hairs on the leaf surface (image: plants.usda.gov). d. Distribution and abundance based on the USGS Nonindigenous Aquatic Species Database (nas.er.usgs.gov). Circle size and color indicates abundance based on number of occurance records. Red asterisks indicate populations to be sampled.