Arctic vegetation history from ancient DNA
We are analyzing ancient DNA preserved in lake sediment (i.e., sedimentary DNA sourced from the multitude of organisms living within a lake catchment) to reconstruct past ecological change on Baffin Island, Arctic Canada. Recent advances in DNA metabarcoding enable us to securely and efficiently identify the local presence of tundra plant taxa over thousands of years. Our paper on the early Holocene colonization of dwarf birch, a temperature-sensitive Arctic shrub, is now out in Global Change Biology. Ancient DNA in lake sediment can also give us a window into the past distribution of other taxonomic groups like mammals, birds, and insects, so stay tuned for more. This work is in collaboration with the TrEnD Lab at Curtin University in Australia.
Photo by Giff Miller
Last Interglacial climate and ecology
Data from Lisiecki and Raymo (2005)
Our NSF-funded project PACEMAP (Predicting Arctic Change through Ecosystem MoleculAr Proxies) is aimed at combining ancient DNA-based paleoecology with paleoclimate insights from lipid biomarkers (branched GDGTs and leaf waxes) in lake sediment to characterize how the Arctic responded to the warmth of the Last Interglacial. Our target lakes cover a latitudinal transect from treeline to the High Arctic and include rare terrestrial records of MIS 5e. We will be working on validating and calibrating these newly developed molecular proxies as well, through monitoring and detailed vegetation surveys. Our collaborators on this project include Elizabeth Thomas of University at Buffalo, Martha Raynolds of University of Alaska Fairbanks, Julio Sepúlveda of INSTAAR, and Mike Bunce of Curtin University.
Recent publication: Crump et al., 2021, PNAS
Early Holocene glacier activity on Baffin Island
How did mountain glaciers respond to past abrupt climate change? We're using cosmogenic Be to date early Holocene moraines in the Baffin Bay region to characterize the glacial response to short-lived cooling events that characterized the North Atlantic region during the early Holocene, à la the 9.3 and 8.2 ka events. Our data point to multiple synchronous glacier advances or stillstands during this period on eastern Baffin Island and western Greenland. This work is in collaboration with Nicolás Young of LDEO and Jason Briner of the University at Buffalo.
Photo by Jason Briner
Unravelling the paleoenvironmental history of Grand Teton NP
Photo by Kory Kirchner
The spectacular Teton Range in Wyoming was formed by uplift along the Teton fault and carved by repeated Pleistocene glaciations. By combining multi-proxy lake sediment studies and cosmogenic radionuclide dating, we are investigating the history of climate, glacier activity, ecological change, and earthquakes in this iconic National Park. I have used Be to date glacier moraines as well as earthquake-triggered landslide deposits. We are currently reconstructing the glacial and environmental response to past abrupt climate changes, including the Younger Dryas cold period and subsequent rapid warming. My upcoming NSF Postdoctoral Fellowship at UC Santa Cruz is aimed at using sedimentary ancient DNA to document ecological responses to rapid deglaciation and warming. This project is in collaboration with Darren Larsen of Occidental College.