P. Schuster and P.F. Stadler, Nature and Evolution of Early Replicons.H.D. Robertson and O.D. Neel, Virus Origins: Conjoined RNA Genomes as Precursors to DNA Genomes.J.S. Semancik and N. Duran-Vila, Viroids in Plants: Shadows and Footprints of a Primitive RNA.C. Biebricher, Mutation, Competition, and Selection as Measured with Small RNA Molecules.A. Meyerhans and J.-P. Vartanian, The Fidelity of Cellular and Viral Polymerases and Its Manipulation for Hypermutagenesis.S. Wain-Hobson and M. Sala, Drift and Conservatism in RNA Virus Evolution: Are They Adapting or Merely Changing?E. Domingo, C. Escarmís, L. Menéndez-Aarias, and J.J. Holland, Viral Quasispecies and Fitness Variations.M.A. McClure, The Retroid Agents: Disease, Function, and Evolution.D. Wodarz and M.A. Nowak, Dynamics of HIV Pathogenesis and Treatment.I.M. Rouzine and J.M. Coffin, Interplay between Experiment and Theory in Development of a Working Model for HIV-1 Population Dynamics.A.J. Gibbs, P.L. Keese, M.J. Gibbs, and F. García-Arenal, Plant Virus Evolution: Past, Present, and Future.M. Gromeier, E. Wimmer, and A.E. Gorbalenya, Genetics, Pathogenesis, and Evolution of Picornaviruses.J.I. Esteban, M. Martell, W.F. Carman, and J. Gómez, The Impact of Rapid Evolution of the Hepatitis Viruses.R.G. Webster, Antigenic Variation in Influenza Viruses.L.P. Villarreal, DNA Virus Contribution to Host Evolution.C.R. Parrish and U. Truyen, Parvovirus Variation and Evolution.D.J. McGeoch and A.J. Davison, The Molecular Evolutionary History of the Herpesviruses.J. Salas, M.L. Salas, and E. ViÃ±uela, African Swine Fever Virus: A Missing Link Between Poxviruses and Iridoviruses?Subject Index.