Collaborative Research: Mobile Elements and Primate Evolution

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Mobile elements are DNA segments that make copies of themselves that are then inserted elsewhere in the genome. These elements can influence many important evolutionary processes, including mutation and rearrangement of chromosomes. They may also play an important role in the development of new species. Although mobile elements make up nearly 30% of the human genome, little is known about their origins and their mechanisms of replication and insertion. The major goal of this research is to learn more about mobile elements and the roles they have played in human and primate evolution. Some mobile elements, particularly those termed Alus and L1s, are either present or absent at a specific chromosome location. Because the presence of a mobile element at a specific location is the more recent, or derived, state, and because these elements are not deleted after they are inserted, these polymorphisms are ideal for evolutionary analysis. In this collaborative project, a series of at least 100 Alu and L1 elements will be ascertained in a diverse collection of at least 16 primate species in order to provide a resource for primate evolutionary studies. Because of the role that some mobile elements play in key evolutionary processes, a comparison of humans with other primate species will help to define unique genetic attributes of our species. Key changes that accompanied human speciation may be identified. Thus, important information about the origins of our species will be obtained. A diverse collection of 300 humans will be typed for 100 L1 insertion elements (this will be added to an existing collection of 100 Alu insertion polymorphisms typed in the same individuals). This will produce a powerful resource for addressing questions about the demographic history of our species. Did anatomically modern humans experience a population bottleneck in their history? If so, how severe was this bottleneck, when did it occur, and where did it occur? This research will help to further test the hypothesis that modern humans originated in Africa, with a small subset of individuals later migrating out of Africa to other parts of the Old World. In addition to addressing questions about human origins, this project will provide a resource of newly identified and characterized mobile elements that can be used by any investigator interested in primate genetics. An important aspect of this project is the training of graduate and undergraduate students and of members of under-represented minority populations.