In this second edition, all of the chapters have been updated and extensively revised to include recent advances in techniques and methods of analysis, and a separate chapter on the polymerase chain has been added. Each chapter emphasizes the conceptual background needed to understand the subject, and then provides a guide to collecting or analyzing data. Included are chapters on sampling design, collection and storage of tissues (a guide to major tissue collections has been added), each of the major molecule techniques, interspecific and phylogenetic analysis, and a review of applications. The technique chapters cover principles, assumptions, applications, limitations, and basic protocols for isozyme electrophoresis, molecular cytogenetics, DNA hybridization, the polymerase chain reaction (PCR), DNA fragments (including microsatellites and RAPDs), restriction sites analysis, cloning and nucleic acid sequencing. The chapters on analysis have been expanded to include the many new developments in techniques for analyzing molecular data, including an expanded discussion of maximum likelihood methods, methods for assessing the results, comparative methods, and models of molecular evolution.