This book focuses on explaining the distribution of sexual systems (simultaneous hermaphroditism, sequential hermaphroditism, environmental sex determination,dioecy, androdioecy, etc.) among taxa, which remains a major challenge in evolutionary biology. Although significant advances have been made for angiosperms, there is not yet a theory that predicts the sexual system for the majority of animal taxa, and other taxa of plants also remain poorly understood. The problem, particularly for animals, is that sexual systems can be very conservative, with whole phyla and classes being characterized by a single sexual system; for example essentially the whole phylum Platyhelminthes is simultaneously hermaphroditic, whereas the Insecta (Hexapoda) and the Tetrapoda among the vertebrates, are exclusively dioecious. Sex allocation theory on the other hand, suggests that sexual systems should be highly responsive to evolution, changing with population density, life span, patterns of resource availability, etc. The book provides an overview of the topic and then presents a series of chapters, each dealing with a taxon with substantial lability in sexual system in order to identify the factors associated with changes in sexual system in each case. By doing so, the authors reveal factors that have not been considered in formal theory but seem to have a major impact on transitions between sexual systems. This book appeals to a wide readership in fields from zoology and evolutionary biology to botany.

Sexual reproduction is a fundamental aspect of life. It is defined by the occurrence of meiosis and the fusion of two gametes of different sexes or mating types. Sex-determination mechanisms are responsible for the sexual fate and development of sexual characteristics in an organism, be it a unicellular alga, a plant, or an animal. In many cases, sex determination is genetic: males and females have different alleles or different genes that specify their sexual morphology. In animals, this is often accompanied by chromosomal differences. In other cases, sex may be determined by environmental (e.g. temperature) or social variables (e.g. the size of an organism relative to other members of its population). Surprisingly, sex-determination mechanisms are not evolutionarily conserved but are bewilderingly diverse and appear to have had rapid turnover rates during evolution. Evolutionary biologists continue to seek a solution to this conundrum. What drives the surprising dynamics of such a fundamental process that always leads to the same outcome: two sex types, male and female? The answer is complex but the ongoing genomic revolution has already greatly increased our knowledge of sex-determination systems and sex chromosomes in recent years. This novel book presents and synthesizes our current understanding, and clearly shows that sex-determination evolution will remain a dynamic field of future research. The Evolution of Sex Determination is an advanced, research level text suitable for graduate students and researchers in genetics, developmental biology, and evolution.

Primary sexual traits, those structures and processes directly involved in reproduction, are some of the most diverse, specialized, and bizarre in the animal kingdom. Moreover, reproductive traits are often species-specific, suggesting that they evolved very rapidly. This diversity, long the province of taxonomists, has recently attracted broader interest from evolutionary biologists, especially those interested in sexual selection and the evolution of reproductive strategies. Primary sexual characters were long assumed to be the product of natural selection, exclusively. A recent alternative suggests that sexual selection explains much of the diversity of "primary" sexual characters. A third approach to the evolution of reproductive interactions after copulation or insemination has been to consider the process one of sexual conflict. That is, the reproductive processes of a species may reflect, as does the mating system, evolution acting on males and on females, but in different directions. In this volume, authors explore a wide variety of primary sexual characters and selective pressures that have shaped them, from natural selection for offspring survival to species-isolating mechanisms, sperm competition, cryptic female choice and sexual arms races. Exploring diverse reproductive adaptations from a theoretical and practical perspective, The Evolution of Primary Sexual Characters will provide an unparalleled overview of sexual diversity in many taxa and an introduction to the issues in sexual selection that are changing our view of sexual processes.

During evolution there have been several major changes in the way genetic information is organized and transmitted from one generation to the next. These transitions include the origin of life itself, the first eukaryotic cells, reproduction by sexual means, the appearance of multicellular plants and animals, the emergence of cooperation and of animal societies. This is the first book to discuss all these major transitions and their implications for our understanding of evolution.Clearly written and illustrated with many original diagrams, this book will be welcomed by students and researchers in the fields of evolutionary biology, ecology, and genetics.

A collection of stories by mothers of transgender and gender variant children.

The first volume to address the study of evolutionary transitions in plants, Major Evolutionary Transitions in Flowering Plant Reproduction brings together compelling work from the three areas of significant innovation in plant biology: evolution and adaptation in flowers and pollination, mating patterns and gender strategies, and asexual reproduction and polyploidy. Spencer C. H. Barrett assembles here a distinguished group of authors who address evolutionary transitions using comparative and phylogenetic approaches, the tools of genomics, population genetics, and theoretical modeling, and through studies in development and field experiments in ecology. With special focus on evolutionary transitions and shifts in reproductive characters—key elements of biological diversification and research in evolutionary biology—Major Evolutionary Transitions in Flowering Plant Reproduction is the most up-to-date treatment of a fast-moving area of evolutionary biology and ecology.

Written by the leading experts in the field, this book examines the evolutionary advantages of gender dimorphism and sexual dimorphism in flowering plants. Divided into three sections: the first introduces readers to the tremendous variety of breeding systems and their evolution in plants and sets the stage for a consideration of the evolution of dimorphism in reproductive and non-reproductive characters. The second section deals with the evolution of secondary sexual characters, including the theory related to the evolution of sexual dimorphism and its empirical patterns, while the last section deals with the genetics of gender expression and of secondary sexual characters.