Following an opening chapter by the late Susumu Ohno on paralogues of sex-determining genes, the five best-studied genes essential for early mammalian gonadal development are portrayed in detail: SF-1 and WT1 and their roles in early events in gonadal development, SRY and SOX9 in testis determination, and the anti-testis gene DAX-1. Subsequent chapters look at the roles of these genes in sex determination in marsupial mammals, birds, reptiles, amphibians and fish, and review the different sex-determining mechanisms, genetic and environmental, that operate in these different vertebrate classes. Two insights emerge: one, that the same basic set of genes appears to operate during early gonadal development in all vertebrates, despite the differences in mechanisms; the other, that sex determination in vertebrates results from a complex network of regulatory interactions and not from a simple hierarchical cascade of gene actions.

Gender (sex) is a set of morphological and physiological characteristics of the organism underlying sexual reproduction, the essence of which is reduced to fertilization, i.e. the fusion of male and female gametes (gametes) zygote, which develops into a new organism.Sexual reproduction of a species is considered as one of the mechanisms of its homeostasis. Thanks to this mechanism, numerous species have an evolutionary advantage. In the book, two authors will discuss the types of genetic sex determination and differentiation, mostly in multicellular animal organisms. Sex determination is both genetic and environmental process, the sex of an individual being established through an alternative physiological solution. There are two main postulated mechanisms of sex determination: genetic (GSD, Genetical Sex Determination) and environmental (ESD, Environmental Sex Determination).

Natural selection operates among individual organisms which differ in their genetic constitution. The degree of hereditary variability within a species is greatly enhanced by cross-fertilization. Indeed, the mechanism of sexual reproduction occurred very early in evolution, for it is seen today even in bacteria. In Escherichia coli, fertilization occurs by passage of the single chromosome from the male into the female bacterium (LEDERBERG, 1959). In multicellular organisms, the separation of germ from soma, and the production of haploid gametes became mandatory. The gametes were of two types. One, extremely mobile, was designed to seek out and penetrate the other, which loaded with nutrients, received the mobile gamete and intiated the development of a new individual. The foundation for true bisexuality was thus laid. In the primitive state of bisexuality, whether an individual is to be a sperm-producing male or an egg-producing female appears to be decided rather haphazardly. In the worm, Banelia viridis, the minute males are parasites in the female. Larvae that become attached to the proboscis of an adult female become males, while unattached larvae sink to the bottom and become females (BALTZER, 1935). The more sophisticated state of bisexuality was initiated by setting aside a particular pair of chromosomes for specialization and making either the male or the female a heterogametic sex. Sex chromosomes as we know them were thus born.

Edited by the world's foremost authorities on the subject, with essays by leading scholars in the field, this work shows how the sex of reptiles and many fish is determined not by the chromosomes they inherit but by the temperature at which incubation takes place.

Encyclopedia of Reproduction, Second Edition, Six Volume Set comprehensively reviews biology and abnormalities, also covering the most common diseases in humans, such as prostate and breast cancer, as well as normal developmental biology, including embryogenesis, gestation, birth and puberty. Each article provides a comprehensive overview of the selected topic to inform a broad spectrum of readers, from advanced undergraduate students, to research professionals. Chapters also explore the latest advances in cloning, stem cells, endocrinology, clinical reproductive medicine and genomics. As reproductive health is a fundamental component of an individual’s overall health status and a central determinant of quality of life, this book provides the most extensive and authoritative reference within the field. Provides a one-stop shop for information on reproduction that is not available elsewhere Includes extensive coverage of the full range of topics, from basic, to clinical considerations, including evolutionary advances in molecular, cellular, developmental and clinical sciences Includes multimedia and interactive teaching tools, such as downloadable PowerPoint slides, video content and interactive elements, such as the Virtual Microscope

Hormones and Reproduction of Vertebrates, Volume 2: Amphibians is the second of five second-edition volumes representing a comprehensive and integrated overview of hormones and reproduction in fishes, amphibians, reptiles, birds, and mammals. The book includes coverage of endocrinology, neuroendocrinology, physiology, behavior, and anatomy of amphibian reproduction. It provides a broad treatment of the roles of pituitary, thyroid, adrenal, and gonadal hormones in all aspects of reproduction, as well as descriptions of major life history events. New to this edition is a concluding assessment of the effect of environmental influences on amphibians. Initial chapters in this book broadly examine sex determination, reproductive neuroendocrinology, stress, and hormonal regulation as it relates to male and female reproductive structure and function. Subsequent chapters examine hormones and reproduction of specific taxa, including anuran amphibians, urodeles, and gymnophionids. The book concludes with an examination of endocrine disruption of reproduction in amphibians. Hormones and Reproduction of Vertebrates, Volume 2: Amphibians is designed to provide a readable, coordinated description of reproductive basics in amphibians, as well as an introduction to the latest trends in reproductive research and a presentation of our understanding of reproductive events gained over the past decade. It may serve as a stand-alone reference for researchers and practitioners in the field of herpetology or as one of five coordinated references aligned to provide topical treatment across vertebrate taxa for researchers, practitioners, and students focused on vertebrate endocrinology. - Covers endocrinology, neuroendocrinology, physiology, behavior, anatomy, and development of amphibian reproduction - Includes pituitary, thyroid, adrenal, and gonadal hormones - Focuses on anuran, urodele, and gymnophiona amphibians - Provides new coverage on environmental disruption in amphibians

Understanding of the origin of species and their adaptability to new environments is one of the main questions in biology. This is fueled by the ongoing debate on species concepts and facilitated by the availability of an unprecedented large number of genomic resources. Genomes are organized into chromosomes, where significant variations in number and morphology are observed among species due to large-scale structural variants such as inversions, translocations, fusions, and fissions. This genomic reshuffling provides, in the long term, new chromosomal forms on which natural selection can act upon, contributing to the origin of biodiversity. This book contains mainly articles, reviews, and an opinion piece that explore numerous aspects of genome plasticity among taxa that will help in understanding the dynamics of genome composition, the evolutionary relationships between species and, in the long run, speciation.

One of the only books to discuss all vertebrates, the fourth edition of Vertebrate Endocrinology has been completely reorganized and updated to explore the intricate mechanisms that control human physiology and behavior as well as that of other vertebrate animals. Perfect for students in endocrinology, zoology, biology and physiology, it allows readers to gain both an understanding of the intricate relationships among all of the body systems and their regulation by hormones and other bioregulators, but also a sense of their development through evolutionary time as well as the roles of hormones at different stages of an animal's life cycle. Chapters have been reorganized to more closely follow traditional classroom presentation and extensive suggested readings are included at the end of each chapter allowing the reader to obtain further information as well as connect concepts to the literature on which the book is based. For the first time, this edition features four-color illustrations. - Provides a complete overview of the endocrine system of vertebrates by first emphasizing the mammalian system as the basis of most terminology and understanding of endocrine mechanisms and then applies that to non-mammals - Introduces the reader to suitable concepts and explanation of jargon so that the reader will be able to delve directly into the primary literature on any endocrine-related topic with a background that will aid in their interpretation of new information - Revised and updated chapter on The Molecular Bases for Chemical Regulation that now includes more evolutionary data - Includes information on endocrine disrupting chemicals and their implications on the health of wildlife and humans