The major themes in the lab are:
- Adaptation to extreme environments
- Overwintering in cold environments
Genomic changes underlying adaptation to extreme environments
Extreme environments impose strong selective pressures on phenotypes and provide a context within which to explore specific questions about differentiation and adaptation. Poecilia mexicana and P. sulphuraria have independently colonized multiple springs with toxic concentrations of hydrogen sulfide (H2S). The sulfide spring fish provide a unique opportunity for an integrative approach to studying adaptation because: 1. the environmental gradients are clearly defined and replicated, 2. the environmental gradients are physiologically explicit, with known biochemical consequences; and 3. the divergence between populations is recent. Together with Dr. Michi Tobler at Kansas State University, we are using sulfide spring populations of Poecilia in three different river drainages to study parallel adaptation, adaptive trait divergence, differentiation in gene sequences, and gene expression patterns.
Antifreeze proteins in polar fish
One mechanism that polar species have evolved to survive in sub-freezing temperatures are antifreeze proteins (AFPs). AFPs have independently evolved at least five times in fish. AFPs interact with the leading edge of a forming ice crystal to reduce the freezing point and are identified as one of the key innovations that have lead to the radiation of species throughout the Southern Ocean. We combined EST sequencing and proteomic analyses to demonstrate that antifreeze protein genes are under diversifying selection and all isoforms are expressed and translated in a single individual (Kelley, Aagaard et al. 2010 J Mol Evol). Arctic and Antarctic eelpouts both have type III AFPs; we are currently sequencing genomes to determine the precise evolutionary history of type III antifreeze proteins (AFPs).
Overwintering in cold environments
Transcriptional changes in response to seasonal changes in brown bears
The brown bear experiences three major physiological shifts during a year, including active season, hyperphagia and hibernation. In collaboration with Profs. Charlie Robbins, Heiko Jansen and Omar Cornejo we are studying the transcriptional response to seasonal changes in brown bears. RNA-sequencing of multiple tissues will reveal complex regulatory changes that occur in response to extreme physiological changes. Here’s a great video about the bear center and some of the research done at WSU: http://www.kcts9.org/programs/in-close/environment/fat-bears
Here’s a video of bears in the yard.
Glacier ice worms (Mesenchytraeus solifugus) are the largest organisms on Earth that spend their entire lifecycles in ice. Ice worms are distributed on coastal and mountain glaciers from central Oregon to southern Alaska and while they are globally rare, local densities can exceed 100 worms per square meter. Thus, ice worms raise a number of evolutionary and ecological questions. How does a relatively large-bodied organism (relative to the microbial life that dominates glacier ecosystems) survive a life in ice? What are the genomic changes that underlie such an extreme phenotype? And, from an ecological role, what role do ice worms play in nutrient-limited, species poor glacier habitats? We are leading an effort to integrate sequencing of the ice worm genome with physiological and ecological data collection to clarify the ice worm story and shed light on how biodiversity arises and is structured in icy landscapes.
Climate change is dramatically altering alpine ecosystems worldwide. Perhaps nowhere are the effects of warming more pronounced than in alpine streams which are fed by meltwater from rapidly dwindling glaciers and snowfields. We are bringing genomic insight to larger, long-term ecological research effort. Specifically, we are sequencing the genomes of high-altitude, imperiled stoneflies (Lednia tumana and Zapada glacier) which we will compare to species that are not closely tied to icy meltwater conditions to understand their evolutionary trajectories. We are pairing this effort with ecophysiological experiments and RNA sequencing to clarify their existing vulnerabilities from an organismal perspective.