Some handy keywords for your enjoyment:
invasion biology, evolutionary ecology, ecological genomics, plant biology, plant-associated microbiomes, population genetics, ancient DNA, ethnobotany, science communication
Adaptive Capacity in Big Sagebrush
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.
Field of big sagebrush and lupines on the edge of Craters of the Moon National Monument. Image by Kathryn Turner.
Image from California Academy of Sciences Herbarium.
Using historical data to understand ecological and evolutionary processes
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
Designing restoration to resist invasion
In collaboration with the Josh Grinath lab and other folks at ISU, we are investigating the lasting effects of ecological disturbance on the post-fire recovery of sagebrush steppe ecosystems. Wildfires are becoming more common as environmental change progresses, destroying entire landscapes and costing the American public billions of dollars annually. Wildfire frequency in many regions is intensified by the invasion of exotic grasses that are highly flammable, and which often replace native plants as burned landscapes regrow. To prevent invasive species from taking over burned landscapes, land managers are increasingly applying seeds of native plants to encourage ecosystem recovery and keep invasive plants at bay. However, there is still much to learn about the factors that determine the success of seed additions in terms of the ability of seeded species to establish, and to suppress flammable invaders. It is also unclear how previous human-caused landscape changes, such as nitrogen pollution or the removal of water-hogging shrubs (a practice common in western USA rangelands), will affect the success of native seed additions and plant recovery from fire. Moreover, it is unclear how different seed mixes repel exotic plants from invading disturbed areas. This research project addresses these issues by building on a long-term experiment investigating the effects of past nitrogen pollution and shrub removal (originally intended to improve rangeland forage) in a highly invaded sagebrush steppe ecosystem. The experimental site was entirely burned in a recent wildfire, providing a unique opportunity to evaluate how a history of nitrogen pollution and shrub removal will influence plant recovery from wildfire. The research team will develop criteria for creating seed mixes that suppress invasive plants, particularly flammable annual grasses, and will determine their effectiveness within the different long term experimental environments present across the study site. The results from this study will aid land managers in choosing native seed mixes that will help to prevent the spread of invasive plants and decrease the risks and costs of future wildfires. This RAPID project was recently funded by the National Science Foundation. More details here.
Barton Road Ecological Research Area, post fire, October 2020. Image by Kathryn Turner.
Putative hybrid diffuse knapweed, Okanagan Valley, British Columbia 2009. Image by Kathryn Turner.
Invading hybrid Diffuse Knapweed
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
Header image: Centaurea diffusa herbarium specimen, Plant Science Center, University of Texas at Austin. Image by Kathryn Turner.