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.

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.

which individuals are heterozygous (H). A review by Selander (1976] comparing these param eters in various populations has been followed by many other studies. In the present volume, J. B. Mitton has used H to evaluate the importance of heterozygosity in natural populations. The degree of polymorphism expressed by P, has been used in several contributions to approach various problems of population genetics. particularly breeding structure and mating systems by Hamrick, Barrett and Shore, Brown, Burdon and Jarosz. as well as Soltis and Soltis, and Wyatt. Stoneburner. and Odrzykoski. New knowledge derived from these investigations has strengthened a point of view already stressed by Darwin: evolution takes place in a complex environment, that can be constantly changing over long periods of time. or can alternate between long periods of relative stability and cycles of rapid change. The most successful plant species become adjusted to these vagaries in several ways, including shifts in heterozygosity. polymorphism and mating systems. The strength of isozyme ana ysis for testing hypotheses is well illustrated by the contribution of the Soltises, who have shown clearly that a previously held hypothesis, predicting self fertilization fortified by polyploid genetic segregations in ferns, must be rejected."

The application of molecular techniques is rapidly transforming the study of plant systematics. The precision they offer enables researchers to classify plants that have not been subject to rigorous classification before and thus allows them to obtain a clearer picture of evolutionary relationships. Plant Molecular Systematics is arranged both conceptually and phylogenetically to accommodate the interests not only of general systematists, but also those of people interested in a particular plant family. The first part discusses molecular sequencing; the second reviews restriction site analysis and the sequencing of mitochondrial DNA. A third section details the analysis of ribosomal DNA and chloroplast DNA. The following section introduces model studies involving well-studied families such as the Onagraceae, Compositae and Leguminosae. The book concludes with a section addressing theoretical topics such as data analysis and the question of morphological vs. molecular data.

which individuals are heterozygous (H). A review by Selander (1976] comparing these param eters in various populations has been followed by many other studies. In the present volume, J. B. Mitton has used H to evaluate the importance of heterozygosity in natural populations. The degree of polymorphism expressed by P, has been used in several contributions to approach various problems of population genetics. particularly breeding structure and mating systems by Hamrick, Barrett and Shore, Brown, Burdon and Jarosz. as well as Soltis and Soltis, and Wyatt. Stoneburner. and Odrzykoski. New knowledge derived from these investigations has strengthened a point of view already stressed by Darwin: evolution takes place in a complex environment, that can be constantly changing over long periods of time. or can alternate between long periods of relative stability and cycles of rapid change. The most successful plant species become adjusted to these vagaries in several ways, including shifts in heterozygosity. polymorphism and mating systems. The strength of isozyme ana ysis for testing hypotheses is well illustrated by the contribution of the Soltises, who have shown clearly that a previously held hypothesis, predicting self fertilization fortified by polyploid genetic segregations in ferns, must be rejected."

Although they are relative latecomers on the evolutionary scene, having emerged only 135-170 million years ago, angiosperms or flowering plants are the most diverse and species-rich group of seed-producing land plants, comprising more than 13,000 genera and over 300,000 species. Not only are they a model group for studying the patterns and processes of evolutionary diversification, outside the laboratory they also play major roles in our economy, diet, and our courtship rituals, producing our fruits, legumes, and grains, not to mention the flowers in our Valentine's bouquets. They are also crucial ecologically, dominating most terrestrial and some aquatic landscapes. This fully revised edition of Phylogeny and Evolution of the Angiosperms provides an up-to-date, comprehensive overview of the evolution of and relationships among these vital plants, as well as of our attempts to reconstruct these relationships. Incorporating molecular phylogenetics with morphological, chemical, developmental, and paleobotanical data, as well as a more detailed account of early angiosperm fossils and important fossil information for each evolutionary branch of the angiosperms, the new edition integrates fossil evidence into a robust phylogenetic framework. Also including a wealth of new color images, this highly synthetic work further reevaluates long-held evolutionary hypotheses related to flowering plants and will be an essential reference for botanists, plant systematists, and evolutionary biologists alike.