Sex Determination and Differentiation in Reptiles PDF Download
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Author: Ettore Olmo
Publisher: S. Karger AG (Switzerland)
ISBN:
Category : Medical
Languages : en
Pages : 152
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Book Description
Reptiles are a fascinating group for the study of sexual development because they exhibit a wide range of sex-determining mechanisms, from strict genetic sex determination (GSD) to strict thermal sex determination (TSD) and intermediate systems of GSD that are to various degrees overridden by environmental effects . This thematic issue presents the latest data on different aspects of sex determination in reptiles. Following an evolutionary perspective on why reptiles might be predisposed to evolve TSD, the papers in this issue explore in detail the different genetic and molecular mechanisms of sex determination and differentiation. They consider recent findings such as the discovery of new genes differentially expressed at male and female sex-determining temperatures, a new model of the role of aromatase, and the contribution of heat-shock proteins to TSD in the American alligator. Further studies examine the role played by sex allocation, the advantage of viviparity, and the effects of anthropogenic climate change on the sex ratio in TSD reptile populations. Providing a valuable overview for both students and researchers, this publication is essential reading for developmental and reproductive biologists, herpetologists, comparative endocrinologists, evolutionary biologists and geneticists.
Author: Ettore Olmo
Publisher: S. Karger AG (Switzerland)
ISBN:
Category : Medical
Languages : en
Pages : 152
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Book Description
Reptiles are a fascinating group for the study of sexual development because they exhibit a wide range of sex-determining mechanisms, from strict genetic sex determination (GSD) to strict thermal sex determination (TSD) and intermediate systems of GSD that are to various degrees overridden by environmental effects . This thematic issue presents the latest data on different aspects of sex determination in reptiles. Following an evolutionary perspective on why reptiles might be predisposed to evolve TSD, the papers in this issue explore in detail the different genetic and molecular mechanisms of sex determination and differentiation. They consider recent findings such as the discovery of new genes differentially expressed at male and female sex-determining temperatures, a new model of the role of aromatase, and the contribution of heat-shock proteins to TSD in the American alligator. Further studies examine the role played by sex allocation, the advantage of viviparity, and the effects of anthropogenic climate change on the sex ratio in TSD reptile populations. Providing a valuable overview for both students and researchers, this publication is essential reading for developmental and reproductive biologists, herpetologists, comparative endocrinologists, evolutionary biologists and geneticists.
Author: Nicole Valenzuela
Publisher: Smithsonian Institution Scholarly Press
ISBN:
Category : Science
Languages : en
Pages : 212
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Book Description
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.
Author:
Publisher:
ISBN:
Category : American alligator
Languages : en
Pages : 2
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Book Description
Author: Kazuya Kobayashi
Publisher: Springer
ISBN: 4431566090
Category : Science
Languages : en
Pages : 783
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Book Description
This book provides new insights into the universality of biological systems in animal reproduction and development by a comparative study of a variety of mechanisms in animals ranging from basal invertebrates to vertebrates, including mammals. Animals accomplish genetic diversity through meiosis and fertilization, and during embryogenesis animals must produce specialized cell types, including germ cells, in accordance with their individual body plan. This series of phenomena is essential to the continuity of life in the animal kingdom, and animals show various reproductive and developmental strategies. This volume, comprising four parts, reviews animal kingdom diversity, including reproductive strategies and germ cell differentiation mechanisms (Part 1), sex determination and differentiation (Part2), the mechanisms of fertilization (Part 3), and body axis formation (Part 4). Readers will find descriptions of the reproduction or development of 180 species, 13 phyla, 35 classes, 74 orders, 117 families, and 151 genera in this book. Of particular interest is the diversity of molecules and mechanisms used to achieve the same biological purpose in different animals. Undergraduates, graduate students, and professional scientists who want a deeper understanding of animal reproductive and developmental mechanisms will find this book to be of great value.
Author: Gerd Scherer
Publisher: Birkhäuser
ISBN: 3034877811
Category : Science
Languages : en
Pages : 210
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Book Description
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.
Author: Susumu Ohno
Publisher: Springer Science & Business Media
ISBN: 3642881785
Category : Science
Languages : en
Pages : 201
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Book Description
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.
Author: Kristen J. Navara
Publisher: Springer
ISBN: 3319712713
Category : Science
Languages : en
Pages : 246
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Book Description
There is extensive evidence that vertebrates of all classes have the ability to control the sexes of the offspring they produce. Despite dramatic differences in the mechanisms by which different taxa determine the initial sex of offspring, each group has found its own way of adjusting offspring sex ratios in response to social and environmental cues. For example, stress is a well-known modulator of offspring sex in members of all groups studied to date. Food availability, and limitation in particular, is another common cue that stimulates biases in offspring sex ratios in a wide variety of species. Offspring sex can be adjusted at the primary level, which occurs prior to conception, or at the secondary level, during embryonic development. While the mechanistic pathways that ultimately result in sex ratio biases and the developmental time-points sensitive to those mechanisms likely differ among taxa, the key involvement of steroid hormones in the process of sex ratio adjustment appears to be pervasive throughout. This book reviews the systems of sex determination at play in different vertebrate groups, summarizes the evidence that members of all vertebrate taxa can facultatively adjust offspring sex, and discusses when and how these adjustments can take place.
Author: Denis Charles Deeming
Publisher:
ISBN: 1897676115
Category : Nature
Languages : en
Pages : 349
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Book Description
Reptiles have been a topic for scientific study for many decades and remain widely studied around the world. In particular, their reproductive patterns and strategies have been extensively studied, proving useful in analysis of life-history strategies. A pivotal aspect of reptilian reproduction is incubation of eggs. Oviparity is found in all turtles, crocodilians and the tuatara and is prevalent in many lizards and snakes. Many aspects of the eggs, embryos and incubation conditions have been the subject of numerous scientific reports. This volume is dedicated to systematic analysis of reptilian incubation. The concept for the book is to look at reptilian eggs, development and incubation conditions in a functional way with particular emphasis on the natural incubation environment and, rather than concentrating on Family accounts, (e.g. incubation in crocodilians) the chapters review the topics in all reptile types allowing for the first time a systematic comparison of incubation between crocodilians, turtles and squamates. In addition to reviewing current information, the authors briefly look towards the future and outline areas where further research is needed.
Author: R. Reinboth
Publisher: Springer Science & Business Media
ISBN: 364266069X
Category : Science
Languages : en
Pages : 464
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Book Description
When Richard Goldschmidt' coined the term "intersexuality" in 1915, he intended it to apply to normally dioecious species which exhibit some kind of mixture between male and female characters. However, as knowledge of the bewildering variability present in the sexual orga nization of members of the animal kingdom has increased, the original meaning of the word has changed. Today many authors define inter sexuality as "the presence of both male and female characteristics, or of intermediate sexual characteristics, in a single individual".2 This more extensive and widely accepted concept justifies the title of our book •. Among all the anatomical and physiological features of living organisms the reproductive system has a unique importance for the perpetuation of the species. Conversely, reproductive processes are of little or no account for the viability of the individual. Therefore, within the framework of general biology reproduction has all too often been looked at solely from the point of view of genetics. Lively discussions about genotypic versus phenotypic sex determination long dominated the sci entific literature on sexuality in animals; this one-sided emphasis has tended to obscure many important facets of an organism's ability to reproduce. Recent developments in current biological research have brought the classic problem of sex differentiation into focus again, and the rapid progress being made in comparative endocrinology has added a new di mension to the study of reproductive biology.
Author: Harold Cogger
Publisher: CSIRO PUBLISHING
ISBN: 1486309704
Category : Science
Languages : en
Pages : 1093
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Book Description
Reptiles and Amphibians of Australia is a complete guide to Australia’s rich and varied herpetofauna, including frogs, crocodiles, turtles, tortoises, lizards and snakes. For each of the 1218 species there is a description of its appearance, distribution and habits. These descriptions are also accompanied by distribution maps and, in many cases, one of the book's more than 1000 colour photographs of living animals. The book also includes 130 simple-to-use dichotomous keys, accompanied by hundreds of explanatory drawings, that in most cases allow a specimen in hand to be identified. In addition, it has a comprehensive list of scientific references for those wishing to conduct more in-depth research, an extensive glossary, and basic guides to the collection, preservation and captive care of specimens. This classic work was originally published in 1975. The updated seventh edition contains a new Appendix that discusses recent changes and lists over 80 new or resurrected species and genera that have been added to the Australian frog and reptile fauna since the 2014 edition.
