Collaborative Research: High-Quality Genome Sequences of Two Divergent Woolly Mammoths

Collaborative Research: High-Quality Genome Sequences of Two Divergent Woolly Mammoths Stephan Shuster and Webb Miller, Penn State University ABSTRACT The woolly mammoth (Mammuthus primigenius) is ideal for making direct observations of the evolution of a mammalian genome and its genes as a species struggles to adapt to environmental changes, ending with extinction of the lineage. Because of the many well preserved specimens, their wide distribution in time and space, and the extensive literature on the species and its habitat, mammoths are the best model system for studying DNA from extinct species. Over the last four years, the field of ancient DNA has been revolutionized by novel sample-preparation methods and next-generation DNA sequencing, resulting in genome-scale projects, as well as population genetic studies based on complete mitochondrial sequences for the woolly mammoth. A recent analysis of these mitochondrial DNA sequences detected a deep split in the woolly mammoth population that has not been observed in the fossil record. Still more recently, a preliminary survey of the mammoths full DNA complement suggested that the split can be observed in two particular specimens, called M4 and M25 for historical reasons. These observations, though quite limited and preliminary, lead to the hypotheses that the woolly mammoth clades exemplified by M4 and M25 were genetically quite distinct, separating over a million years ago, and that M25s clade became extinct well before coming into contact with humans. The methods employed in this project will refine genomic sequencing and ultimately lead to a greater understanding of wooly mammoth genomic evolution over the last 100,000 years. The PIs have published initial results in the November, 2008 issue of Nature. The publication brought broad press coverage and has since been incorporated into secondary school teaching. This research has proven to be transformative not only in its scientific results but its stimulation of the scientific and lay public communities.