|
In the 1980s rampant poaching fueled by a demand for ivory wiped out hundreds of thousands of African elephants. Consequently the population plummeted from over a million animals to 500,000. Such sharp declines lead to what biologists call a population bottleneck, a situation that results in a loss of genetic variation and increased inbreeding due to the reduced population size. At their worst population bottlenecks jeopardize the survival of a species. Biology graduate student Siri Nelson is working to understand how much genetic variation remains among elephant populations and if and how migration keeps remnant populations connected.
Working with Biology research professor Sam Wasser in the Center for Conservation Biology, Siri is using genetic tools to study variation among elephant populations from central to southern Africa. Siri’s data should help reveal the answers to several significant open questions about elephant dynamics including how different populations are related and the location of migration corridors. Knowing where migration occurs is important because preserving these routes is crucial to preventing populations from becoming increasingly fragmented. Poaching caused the precipitous population drop, but additional pressures such as habitat loss and destruction, which result in limited migration, exacerbate such declines. The more fragmented the population, the more severe the effects of a population bottleneck.
|
Last summer Siri traveled to Africa to visit elephant country for the first time. Prior to this trip her only contact with elephants was through their DNA in the lab. Needless to say, she felt disconnected from their ecology and natural history. Visiting the site of any research organism provides immense insight into relevant questions and hypotheses and Siri’s trip helped her clarify and focus her dissertation goals.
While in Africa, Siri collected more DNA samples for her project. Since trapping elephants and taking blood samples is not quite as easy as it is for many smaller organisms, elephant DNA samples come from scat. So Siri traveled around southern Africa with a cooler, many vials, and many, many gloves. Back in the lab her collecting will pay off by giving her a finer genetic resolution to determine how migratory routes have changed over time and whether there is one species of African elephant, as has long been thought, or two (forest and savannah species).
This latter two species hypothesis is founded on observations of elephant ecology; that is, elephants live in many different habitats. The stereotypical image of an elephant puts it on a savannah. But in reality they can also be found in dry forests, deserts, temperate regions of southern Africa, and, of course, around watering holes. If elephants living in any of these diverse habitats mate assortatively, and if different adaptations are required to survive in different habitats, then there is the opportunity for genetic divergence and even speciation to occur. Thus, despite the population bottleneck, Siri may find more genetic variation than would otherwise be expected.
Siri’s research has another compelling component: Increasing the understanding of how elephant populations are connected enhances the capabilities of the Center for Conservation Biology’s ivory poaching project by providing greater precision in their work. The Center currently collaborates with Interpol to determine the origin of illegally poached ivory. By extracting DNA from confiscated tusks, the Center compares genetic “fingerprints” to a continent-wide reference map constructed using DNA from scat samples. By pinpointing the origins of illegally poached ivory, law enforcement officials can concentrate their efforts in regions most at risk for poaching.
Siri’s Path to Conservation Biologist
Siri is a native Seattleite. She went to Garfield High School where she was part of the science magnet program. Through this program she took an urban ecology course and a class on marine science and discovered how much she liked the scientific process and fieldwork in particular. Funded by beach clean-ups, her class took a two-week field trip to the big island of Hawaii and spent a lot of time learning about the natural history of the island, impressing upon her the importance of such knowledge. Since then Siri’s path toward a career in conservation has been ardently focused.
For her bachelor’s degree Siri attended the Evergreen State College, where she majored in biology, ecology, and environmental science. Further pursuing education in conservation biology, Siri went to a field school in Australia for a semester where she studied habitat fragmentation as a model for island biogeography. During this time Siri realized that genetic and molecular tools greatly facilitate the understanding of population behaviors like migration. So following college she got a job specifically to improve her understanding of and ability to use these tools.
For four years Siri worked at the Seattle Biomedical Research Institute on several genome projects including one study investigating the genetic variation found in the surface binding proteins of malaria. After honing her skills as a molecular biologist, Siri applied to graduate school specifically to work with Sam. She is currently in her fourth year as a graduate student.
In Siri’s scant free time she can usually be found working in her garden or tending to her three chickens, both part of her conscientious effort to lead an environmentally-friendly lifestyle. She loves hiking, reading feminist blogs, and has spent time working at a homeless shelter. She has also been on the Department of Biology’s undergraduate curriculum committee for two and a half years and is currently working with faculty to identify learning goals for undergraduate students who major in biology. Provided funding is available, Siri plans to return to Africa next summer to collect more samples.
To learn more about research being conducted in the Center for Conservation Biology and how you can help support it, visit their website: http://depts.washington.edu/conserv/.