Polyploidy plays an important role in biological diversity, trait improvement, and plant species survival. Understanding the evolutionary phenomenon of polyploidy is a key challenge for plant and crop scientists. This book is made up of contributions from leading researchers in the field from around the world, providing a truly global review of the subject. Providing broad-ranging coverage, and up-to-date information from some of the world’s leading researchers, this book is an invaluable resource for geneticists, plant and crop scientists, and evolutionary biologists.

Polyploidy – whole-genome duplication (WGD) – is a fundamental driver of biodiversity with significant consequences for genome structure, organization, and evolution. Once considered a speciation process common only in plants, polyploidy is now recognized to have played a major role in the structure, gene content, and evolution of most eukaryotic genomes. In fact, the diversity of eukaryotes seems closely tied to multiple WGDs. Polyploidy generates new genomic interactions – initially resulting in “genomic and transcriptomic shock” – that must be resolved in a new polyploid lineage. This process essentially acts as a “reset” button, resulting in genomic changes that may ultimately promote adaptive speciation. This book brings together for the first time the conceptual and theoretical underpinnings of polyploid genome evolution with syntheses of the patterns and processes of genome evolution in diverse polyploid groups. Because polyploidy is most common and best studied in plants, the book emphasizes plant models, but recent studies of vertebrates and fungi are providing fresh perspectives on factors that allow polyploid speciation and shape polyploid genomes. The emerging paradigm is that polyploidy – through alterations in genome structure and gene regulation – generates genetic and phenotypic novelty that manifests itself at the chromosomal, physiological, and organismal levels, with long-term ecological and evolutionary consequences.

Recent major advances in the field of comparative genomics and cytogenomics of plants, particularly associated with the completion of ambitious genome projects, have uncovered astonishing facets of the architecture and evolutionary history of plant genomes. The aim of this book was to review these recent developments as well as their implications in our understanding of the mechanisms which drive plant diversity. New insights into the evolution of gene functions, gene families and genome size are presented, with particular emphasis on the evolutionary impact of polyploidization and transposable elements. Knowledge on the structure and evolution of plant sex chromosomes, centromeres and microRNAs is reviewed and updated. Taken together, the contributions by internationally recognized experts present a panoramic overview of the structural features and evolutionary dynamics of plant genomes.This volume of Genome Dynamics will provide researchers, teachers and students in the fields of biology and agronomy with a valuable source of current knowledge on plant genomes.

The nature of populations, races, subspecies, and species. Genetic basis of isolation. Origin of isolation - theoretical. Origin of isolation - experimental. The nature of the speciation process.

Polyploidy as a dramatic mutational event in the process of evolution has wide implications in nature and for the generation of new and improved crops. The three day Conference on POLYPLOIDY: BIOLOGICAL RELEVANCE focused on three aspects of this natural phenomenon: the first emphasized the characteristics of polyploidy, the second described the occurrence of polyploidy among plants and animals, and the third considered past and future areas of both fundamental and pragmatic research that involve polyploidy. New information relative to origin, cytogenetics, ecology, physiology, biochemistry, and populational studies stress the need to reexamine current views on the origins of polyploidy and its significance among both plants and animals. There are major differences in the occurrence of polyploidy between. plant groups and it is proving a much more common event among bisexual vertebrates than heretofore considered possible. Crop development and improvement must utilize approaches based fundamentally on more natural systems; in fact future research should focus more on polyploidy as a natural phenomenon that needs study at all levels of endeavor from field-oriented populational aspects to sophisticated molecular analyses and genome manipulations. This volume provides a summary of current knowledge of polyploidy pertinent to botanists, zoologists, and agriculturists who are interested in the evolution o~natural systems and who are concerned with the contribution that crop improvement can make to human well-being. Walter H. Lewis St. Louis, Missouri October, 1979 v ACKNOWLEDGMENTS The Host Committee thanks all speakers and moderators for their generous contribution to the Conference and to this volume.

The field of plant taxonomy has transformed rapidly over the past fifteen years, especially with regard to improvements in cladistic analysis and the use of new molecular data. The second edition of this popular resource reflects these far-reaching and dramatic developments with more than 3,000 new references and many new figures. Synthesizing current research and trends, Plant Taxonomy now provides the most up-to-date overview in relation to monographic, biodiversity, and evolutionary studies, and continues to be an essential resource for students and scholars. This text is divided into two parts: Part 1 explains the principles of taxonomy, including the importance of systematics, characters, concepts of categories, and different approaches to biological classification. Part 2 outlines the different types of data used in plant taxonomic studies with suggestions on their efficacy and modes of presentation and evaluation. This section also lists the equipment and financial resources required for gathering each type of data. References throughout the book illuminate the historical development of taxonomic terminology and philosophy while citations offer further study. Plant Taxonomy is also a personal story of what it means to be a practicing taxonomist and to view these activities within a meaningful conceptual framework. Tod F. Stuessy recalls the progression of his own work and shares his belief that the most creative taxonomy is done by those who have a strong conceptual grasp of their own research.