Using ancient DNA to investigate the influence of environmental change on animal populations
Open Access
- Author:
- Letts, Brandon
- Graduate Program:
- Genetics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 16, 2011
- Committee Members:
- Beth Shapiro, Dissertation Advisor/Co-Advisor
Stephen Wade Schaeffer, Committee Chair/Co-Chair
Russell W Graham, Committee Member
Iliana Brigitta Baums, Committee Member
Daniel Bradley, Committee Member
Beth Shapiro, Committee Member - Keywords:
- Pleistocene
Holocene
bison
armadillo
steamer duck
caribou
environment
evolution
glaciation - Abstract:
- The last 2.58 million years have been characterized by several glacial cycles, the most recent of which, called the Wisconsinan in North America, ended only ten thousand years ago (kya). Using ancient DNA, I investigate the evolutionary history of four groups of animals that have had evolutionary histories shaped by the environmental changes associated with these glacial cycles. By collecting DNA from the Holocene epoch (10 kya to present), I investigate fine-scale responses of North American bison to the onset of an interglacial climate and illustrate that known environmental and anthropogenic events could be tied to the decline and extinction of the steppe bison. I provide the first evidence of bison migration northward through the ice-free corridor that was in northwestern Canada. I investigate the temporal genetic stability of caribou populations living in the Northwest Territories, Canada throughout the past 3,800 years to test if they were affected by a volcanic eruption ~1.1 kya and assess the genetic support for the subspecific identification of caribou ecotypes. In the first paleogenetic analysis of armadillos, I illustrate that North American fossils assigned to Dasypus bellus (the beautiful armadillo) genetically assign to two species, one of which likely represents the ancestor of the modern nine-banded armadillo. Finally, historic and modern DNA is used to determine the phylogeny of the steamer ducks of South America and hypothesize how past glacial environmental changes may have shaped their current genetic diversity and distribution. I show that several of these groups were often more flexible than expected, adapting to environmental changes within short periods of time. I also show that ancient DNA is available from regions like subtropical Florida and Texas that were previously assumed to be too hostile for DNA preservation.