GENOMICS OF THE WOOLLY MAMMOTH'S EXTINCTION
In my PhD research, I combine the fields of palaeogenomics and conservation genomics to study pre-extinction genetic processes in the last population of the woolly mammoth before its extinction.
African Elephants in Addo National Park, South Africa. Gorgo/Wikimedia Commons
Many endangered populations of today are facing the consequences of habitat fragmentation, isolation, and small population size. The smaller the population, the more vulnerable it is to random events and processes pushing it closer to extinction. Such stochastic events might occur in the environment, like hurricanes or severe droughts, but they might also occur in DNA. And the villains in this story are called inbreeding and genetic drift.
To what extant are inbreeding and genetic drift to be blamed for a species' extinction is not completely clear. Among other things, studying these processes in natural populations is difficult and our current knowledge is based more on theory than empirical evidence. However, high-thoughout sequencing is working miracles and thanks to the advances in ancient DNA techniques, we can travel back in time, which gives us a unique opportunity to learn about extinction from the most adequate source.
Who can teach us more about extinction then an extinct species? A species that lived in isolation, at a fraction of its original population size?
Charles R. Knight, 1920
The woolly mammoth was one of the most common and widespread Pleistocene megafaunal species, with a range stretching from the British Isles, across Eurasia, and into North America. The process of its extinction probably started with a complex series of climatic and environmental changes, as well as hunting by expanding human populations. After becoming extinct throughout most of its range at the end of the last ice age, the woolly mammoth survived in small isolated populations on islands off the coasts of Siberia and Alaska. Wrangel Island was the terminal refugium where mammoths became extinct 4 thousand years ago, approximately 6 thousand years after separation from the Siberian mainland.
Because of its evolutionary history and long-term isolation on a small island, the woolly mammoth is an excellent model system for studying basic conservation genomic principles, such as the effect that bottlenecks and long-term small population sizes have on neutral and adaptive genetic diversity.
My PhD project is supervised by Prof. Love Dalén at the Swedish Museum of Natural History