Big sagebrush (Artemisia tridentata) is a foundational species of the North American West. Threatened and endangered species rely on it. And yet the range of this iconic species is shrinking, due to pressure on several fronts, including invasive species, encroaching native species, altered fire regimen, and climate change. The Turner Lab is working to understand the evolutionary impact that invasive species and land use change has had on big sagebrush, and how big sagebrush may be able to adapt to and succeed in the face of these pressures. This work is part of the NSF-funded Idaho EPSCoR GEM3 research program, a large and collaborative network of transdisciplinary scientists and stakeholders across Idaho.

Biological invasions of non-native species present compelling motivation to understand how human-induced changes in the environment and species distributions influence ecological and evolutionary processes. Their documented geographic spread across time makes them ideal for study using historic collections, allowing better insight to evolutionary change over short time scales. Applying advanced genomic approaches to historic samples is key to understanding the processes that allow plants to rapidly establish and adapt to new environments. Theory predicts that dramatic ecological and evolutionary changes affect invasive species soon upon arrival in a new habitat. Yet current research relies on sampling contemporary populations, and therefore reveals little about the initial stages of invasion. Here, we study of the history of an invasive weed by exploiting an untapped historical resource to observe “snapshots” of the initial stages of invasion and the genetic changes that occur as a plant species spreads. It involves sampling genetic material from dried plant specimens collected throughout the course of an invasion, from herbarium collections across North America. Techniques for ancient DNA originally developed to study long extinct organisms such as mammoths are being used to study evolution over the course of the 100 year invasion of North America by crossflower (Chorispora tenella, Brassicaceae), a widespread and governmentally listed noxious invasive weed. See more at the project website, here.

Collaborators: Ruth Hufbauer, John McKay, Hernán Burbano, Rafal Gutaker

Heterosis has also been hypothesized to contribute to invasion success. Previous work, including my comparison of transcriptome libraries from the native and invaded ranges (Lai et al., 2012), has shown that Centaurea diffusa individuals of hybrid ancestry (with introgression from C. stoebe ssp. stoebe) are more common in the invaded than the native range, though hybridization occurs in the native range only. My work assesses the impact of this heterosis on phenotypic and genetic divergence in the invaded range.

Collaborators: Kate Ostevik, Loren Rieseberg