The laboratory will use improved methods for comparing genes from living specimens and also ancient remains in order to build evolutionary trees and suggest time scales for organizing knowledge of biological diversity within and among animal species, including humans. Specifically, this project will determine the sequence of bases present in pieces of genes from the mitochondria of about 600 individuals and 110 species. Mitochondrial DNA (mtDNA) is maternally inherited and evolves 5 to 10 times as fast as nuclear DNA. Because different parts of the mtDNA molecule evolves at different rates, mtDNA has proven useful for studying a broad range of evolution relationships, from ones as close as among humans to ones as distant as between fishes and humans. Comparison of the sequences will also permit testing ideas about what determines the rate of molecular evolution in such diverse animals as mammals, bird, insects, sea urchins, and worms. The genealogical framework to be provided for human mtDNA is likely to give new insights into human evolution and genetic diversity. In particular, these studies are expected to augment knowledge of the rime and place of human origin and enable the prehistoric processes of migration and population expansion across the Old World into Oceania and the New World to be examined in new ways. The technique for obtaining each DNA sequence employs the polymerase chain reaction. This method starts with the DNA in a tiny amount of tissue and makes up to a million copies of a specific segment of this DNA, which can then be sequenced directly. Because the method avoids the tedious steps of cloning and searching for the desired clone among thousands of millions of others, obtaining DNA sequences of hundreds of individuals (humans and animals) can be done after collection of a drop of blood or a few hairs. In addition, this technique makes the world's storehouse of museum specimens, as well as other ancient remains, accessible to molecular genetic analysis. This project will seek to improve further the methods of gathering DNA sequences, particularly with respect to retrieving sequences from museum specimens and ancient remains.
