Understanding the responses of species to historical shifts in climate informs predictions of the future impacts of human-mediated global changes on biological ecosystems. Mountainous terrain contains a wide range of habitats and diverse species, which have been shaped by a history of major climate changes since the last ice age. These changes include rapid and major changes in vegetation (i.e., shifts from tundra to forest). Mountainous regions are also thought to harbor biodiversity in refugia during otherwise inhospitable climate periods. This project will characterize an ice-age refugium that may have harbored a wide diversity of plant and animal species in steep terrain in northern Idaho, and thus illuminate how mountainous terrain may buffer populations through major climate changes. Focusing on two, dominant tree species in northern coniferous forests (western redcedar and mountain hemlock), this project will integrate three methodological approaches to leverage their complementary strengths in inferring past population sizes and locations. First, cutting-edge DNA-sequencing methods will reveal the genetic footprints of species' migration pathways and test for the existence of refugia. Second, new paleoecological records of pollen and macrofossils will reveal the regional plant species composition and climate during the coldest periods in the past 50,000 years. Third, simulations of historical climate across the complex mountainous landscape will be combined with information on the physiological tolerances of each species (e.g., cold hardiness), to reveal the most likely locations of refugia within this region.
The interdisciplinary approach of this project provides an opportunity to train the next generation of biogeographers, who will need these traditionally distinct skill sets in genetics, paleontology, and landscape modeling to forecast ecological impacts of future climate change. Graduate students will rotate among genetics, paleoecology and landscape ecology labs to achieve this training goal. In addition, a curriculum workshop will be conducted for high school teachers, and used to develop lessons for hands-on activities.
