Integrative and Comparative Biology Advance Access originally published online on June 1, 2007
Integrative and Comparative Biology 2007 47(5):789-790; doi:10.1093/icb/icm009
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Book Review |
Reproductive Biology and Phylogeny of Gymnophiona (Caecilians). Jean-Marie Exbrayat, editor.
Department of Structural and Functional Biology
University of Naples Federico II, Naples, Italy
Correspondence: E-mail: rastogi{at}unina.it
Reproductive Biology and Phylogeny of Gymnophiona (Caecilians). Jean-Marie Exbrayat, editor.Enfield: Science Publishers, 2006. 395 pp. ISBN 1-57808-312-5, 978-1-57808-312-1.
This book is the 5th volume in Science Publishers’ Reproductive Biology and Phylogeny, a series in which each volume is dedicated to provide a comprehensive and accurate synthesis of our knowledge of one animal group. Gymnophiona (caecilians) are probably the most poorly known amphibian subgroup, and this volume is "perhaps" the first and only book that specifically deals with phylogeny and reproduction of this vertebrate subgroup. The editor of this volume, Jean-Marie Exbrayat, is a renowned researcher in the field of reproduction and development in caecilians. He has skilfully put together a series of chapters on caecilian phylogeny and biology by well-known authorities. This book should serve as a very convenient and comprehensive source of information on phylogeny, morphology, reproduction and development of caecilians. A feature that will make this volume attractive to readers who are interested in caecilian phylogeny and/or reproduction, is the inclusion of "concluding remarks" at the end of some chapters.
The volume is organized into 12 chapters. In the introductory chapter, M. H. Wake provides in brief the history of research on caecilian life history and reproduction. In the second chapter, M. Wilkinson and R. A. Nussbaum provide a most interesting and comprehensive review of caecilian phylogeny and classification. Chapter 3, by J.-M. Exbrayat and J. Estabel, begins with an overview of the anatomy common to all caecilians, and provides a thorough description of the male reproductive system. Chapter 4, by a group of researchers from India, summarizes and very nicely illustrates the morphological and functional aspects of the Mullerian duct in the adult male. Of all vertebrates known today, only caecilians show this unique feature. The evolutionary significance of this characteristic has been debated. Chapter 5, by J.-M. Exbrayat is a treatise of the known facts on the reproductive endocrinology of caecilians. Although there is lack of data on hormonal factors, on the basis of morphological studies it is speculated that external factors trigger the cascade of endocrine events leading to reproduction. Chapter 6 on spermatogenesis, by several authors, provides morphological details of this process in caecilians but also indicates the great paucity of information on the dynamics and regulation of spermatogenesis. Chapter 7, by D. M. Scheltinga and B. G. M. Jamieson, is a beautifully illustrated survey of the ultrasonic features and phylogeny of caecilian spermatozoa pointing to the existence of some plesiomorphic characters. This chapter in particular seems to have more detailed pictures and diagrams than the others. Chapter 8, by J.-M. Exbrayat, is a brief and informative, without being overwhelming, exposition of data on oogenesis and folliculogenesis with the major details coming mainly from Typhlonectes compressicauda and also from Ichthyophis beddomei. The author competently makes it clear that much remains to be done. Chapter 9, by E. Anjubault and J.-M. Exbrayat, is a brief analysis of the gonadal development exclusively in T. compressicauda. Whereas other species of Gymnophiona have not been exploited in this field yet, it is here speculated that a delayed sexual differentiation of gonads in the order Gymnophiona might explain the persistence of Mullerian glands in adult males. In chapters 10 and 11, the reproductive modes of caecilians have been nicely reviewed. Many species are viviparous, and chapter 11 emphasizes clearly that T. compressicauda is the caecilian most adapted to the viviparous mode of reproduction. The volume concludes with chapter 12 on fertilization and development comprehensively reviewed by J.-M. Exbrayat. The only shortcomings of this volume seem to be the poor quality of some photographic illustrations in chapters 4 and 5 and the total lack of end comments to call attention to a hot area of research in many chapters.
The scarcity of scientific data, as compared to that available for other amphibian orders, regarding any aspect of Gymnophiona can logically be accounted for the enormous difficulties encountered in collecting, let alone the possibility of rearing these "fossorial" animals of the tropical regions under laboratory conditions. Thus, this book should be as useful and interesting to the expert exploring caecilian phylogeny and reproductive biology as it should be to students and to the biological and non-biological community at large.
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