Copulatory organs (hemipenes) of male snakes vary markedly among species in shape and ornamentation. We suggest that sexual conflict over copulation duration may have shaped the evolution of hemipenis morphology, favouring more elaborate organs in species in which a long duration of copulation is especially beneficial to males, despite the associated costs to females. To test this proposition, we compare mating behaviour between two species of gartersnakes differing in hemipenis morphology. In addition, we review data on copulation duration and hemipenis morphology and relate hemipenis morphology to phylogeny among of New World natricines. As predicted, copulation duration was significantly shorter in the common gartersnake (Thamnophis sirtalis), a species with simple subcylindrical hemipenes, than in the plains gartersnake (Thamnophis radix), a species with more complex, bilobed organs. Furthermore, female T. radix frequently exhibited vigorous body rolls during copulation, a behaviour associated with copulation termination, whereas female T. sirtalis never exhibited this behaviour. Copulations were of shorter duration when female T. radix (but not T. sirtalis) more greatly exceeded males in body size, suggesting that females can more easily disengage from small males. Our review of New World natricines provides only weak evidence for an association between copulation duration and hemipenis morphology. Our mapping of hemipenis morphology onto the New World natricine phylogeny suggests that hemipenis morphology is evolutionarily plastic; both simple and bilobed hemipenes occur in all three major natricine clades, as well as in two of three gartersnake subclades and several sister-species pairs.

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Price not available.With an ever-increasing number of people including wildlife watching in their yearly activities this volume will serve a vital function in providing the layman, and mammalogists with a means for identification of marine mammals. While there are good field guides for limited geographic areas, the present guide provides a single comprehensive guide covering all of the world's marine mammals, including whales, porpoises, dolphins, seals, otters, and polar bears. This book is designed for this purpose, and achieves its goal.The book is divided into seven main chapters or sections, preceded by abstract, preface, and acknowledgments. The introductory section is devoted to general remarks on oceanography and distribution of marine mammals, identification and how to use the key, species codes of the United Nations Food and Agricultural Organization (FAO), and a superbly illustrated glossary of technical terms used throughout the volume.Keys for both external and cranial features are well illustrated. Seventy-eight extant species of Cetacea divided into two suborders (Mysticeti and Odontoceti), cover some 162 pages (pp. 40-202) of text. The main body of the text consists of species accounts. A typical species account is two pages long and includes names used by the FAO in English, French. and Spanish. along with sections on distinctive characteristics, size, geographic distribution, ecology, behavior, and remarks on species that could be confused with the species being discussed. This is followed by remarks on exploitation and status listed by the International Union for the Conservation of Nature and Natural Resources when known. The section on geographic distribution is supplemented with a distribution map for each species covered in the text. Each species is provided with dichromatic-lateral-view illustrations, along with dorsal. ventral, and lateral views of the skull.The second order covered is a to-page chapter on the four known species of sirenians, followed by a 82-page review of the order Carnivora, divided into the suborder Pinnipedia, with some 34 species of pinnipeds assigned to three families, the Otariidae (sea lions and fur seals) with 14 species recognized, the Odobenidae with one extant species, the walrus, and Phocidae (true seals) with 19 species. The remaining six-page section covers the sea otter, marine otter, and polar bear. What makes this book even more spectacular is that the authors also included the four species of cetaceans, two seals, and one sirenian that are found only in fresh water.In the section on Carnivora, Platanista gangetiea and P. minor are considered distinct species, although considerable controversy questions this distinction. The sperm whale is referred to Physeter catodon, although P. macrocephalu.s is cited under other scientific names still being used. Otaria hyronia is used for the South American sea lion, although O. jfavescens also is currently being used (Nowak, 1991; Wilson and Reeder, 1993).Following the species accounts there is a table consisting ...