Fundamentals of Molecular Evolution

Abstract

The objectives in studying molecular evolution are (1) to reveal the nature of change, over time, in genetic materials (nucleic acids) and the products they encode and (2) to deter- mine the exact historical course of those changes within and among organisms. These objectives require an understand- ing of organismal genealogy, which, of course, remains in- complete. It is reasonable, however, to hope for improve- ment in this understanding, both because of increasing resolution from morphological studies and because studies of molecular evolution and organismal phylogeny are mutu- ally illuminating. Phylogenetic hypotheses indicate the direc- tion ofmolecular changes over time, and observed molecular differences among species provide data for further phyloge- netic analyses. This vital relationship has led to an integra- tion ofphylogenetic research and molecular data sets (molec- ular systematics), an integration which many now consider a major component of molecular evolutionary research, in addition to the two points listed above.