Evolutionary genomics in extreme environments: from fish to bears

Joanna KELLEY
School of Biological Sciences, Washington State University, USA joanna.l.kelley@wsu.edu
 

(Seminar in English)  

Organisms inhabit most of the globe and have adapted to all types of extreme environments. By analyzing genomes of organisms adapted to extreme environments we aim to understand the genomic basis of adaptation. The talk will highlight two studies: transcriptomes of fish living in sulfidic streams and hibernating bears. Multiple populations of Poecilia fish have adapted to hydrogen sulfide-rich springs from ancestral freshwater streams, making them an ideal system to study the reproducibility of the evolutionary process. Hydrogen sulfide (H₂S) interrupts the mitochondrial respiratory chain and is also associated with severe hypoxia, and therefore highly toxic. Comparing transcriptional changes across replicated pairs of sulfidic and non-sulfidic populations, we identify convergent evidence of differential expression. RNA-sequencing data from gills provides unique evidence for the genomic and transcriptional basis of adaptation to an extreme environment. Another area of research in my laboratory is in brown bears (Ursus arctos), which are superbly adapted to live in cold, high latitude environments in which they experience an annual winter food shortage. To survive such conditions, they undergo seasonal shifts from maximizing energy gain and energy storage (summer/fall) to conserving energy in winter hibernation. Using RNA-sequencing, we examine the transcriptional changes that occur in muscle, liver, and adipose tissues of captive brown bears in active, hyperphagic, and hibernation states. We identify differentially expressed genes among the three metabolic states. We find significant differential expression between hibernation and the other seasons in all three tissues, with the highest number of changes occurring in adipose tissue.

Recent publications:

Brown, A.P., Greenway, R., Morgan, S., Quackenbush, C.R., Giordani, L., Arias Rodriguez, L., Tobler, M., Kelley, J.L. (2017) Genome-scale data reveals that endemic Poecilia populations from small sulfidic springs display no evidence of inbreeding. Molecular Ecology. doi: 10.1111/mec.14249.

Passow, C.N., Henpita, C., Shaw, J.H., Quakenbush, C.R., Warren, W.C., Schartl, M., Arias-Rodriguez, L., Kelley, J.L., Tobler, M. (2017) The roles of plasticity and evolutionary change in shaping gene expression variation in natural populations of extremophile fish. Molecular Ecology. doi:10.1111/mec.14360.

Kelley, J.L., Passow, C.N., Arias Rodriguez, L., Patacsil Martin, D., Yee, M.C., Bustamante, C.D., Tobler, M. (2106) Mechanisms underlying adaptation to life in hydrogen sulfide rich environments. Molecular Biology and Evolution. doi:10.1093/molbev/msw020.