Placental matrotrophy has evolved independently in many lineages, which is indicative of strong selection. Several ad-hoc hypotheses and one mathematical model have been proposed to explain its evolution, but little experimental data exists to support these claims. Recent studies have attempted to find correlates between placental matrotrophy and other life history traits, but the only common correlate found was a reduction in reproductive allocation (RA). Here I report on three studies. The first two focus on the Trexler-DeAngelis model for the evolution of matrotrophy. In chapter one, I use closely related placental and non-placental species from the northern clade of Poeciliopsis to test an assumption imperative to the model, that placental species abort a subset of developing offspring in low food conditions. The results show no evidence of abortion due to food level. Instead, placental species appear to be tethered to a brood once initiated, and sacrifice body condition to maintain reproduction when resources are restricted. However, an alternative explanation for these results is that the pattern of resource allocation is a function other life history traits, rather than placentation alone. Chapter two distinguishes between these alternatives, by performing a similar experiment on the southern clade of Poeciliopsis, which has the opposite relationship between life history traits and placentation seen in the northern clade. The results mirror those from the northern clade, indicating reproductive mode, rather than life history, dictates the pattern of resource allocation. This further adds to the difficulties of explaining the evolution of the placenta within the constraints of the Trexler-DeAngelis model. The third study characterizes locomotor consequences related to differences in reproductive allocation using the Trinidadian Guppy (Poecilia reticulata), because placentation is correlated with a reduction in reproductive allocation. Females with the highest RA were less streamlined, had lower escape velocities, and had to work harder during prolonged swimming. In low predation natural habitat, these same females were restricted to habitat with slower moving water, while females with lower RAs were able to use faster flows, which are thought to be preferred feeding grounds. All high predation fish used slow moving water, irrespective of RA.

"Understanding reproduction in marine fishes is critical to their conservation. It is also a fascinating topic in its own right. This book is now the best single reference on the subject, with original insights, analysis, and information. Anyone interested in the fascinating diversity of ways fish reproduce will want to have a copy of this book handy."--Peter Moyle, co-author of Protecting Life on Earth "Cole has assembled the internationally recognized authorities and they successfully cover topics of critical interest to behaviorists, ecologists, anatomists, physiologists, and conservation biologists. These experts demonstrate the amazing diversity and complexity of sexual and reproductive characteristics that have evolved among marine fishes."--Gene Helfman, co-author of The Diversity of Fishes: Biology, Evolution and Ecology "Kathleen Cole and her contributing authors raise from the depths of ignorance many neglected themes in the reproductive biology and fluid sexuality of marine fishes. The sheer richness of the data and the enthusiastic, engaging and thoughtful ways in which they are presented will encourage further research and discovery in biology of marine fishes and their complex and dynamic habitats."--Lynne Parenti, co-author of Comparative Biogeography

The animals loosely termed fish constitute more than half of all known vertebrate species. There are approximately 27,000 described living species of bony fishes (Euteleostomi = Osteichthyes), about 70 species of hagfishes and some 34 species of lampreys. Approximately 970 species are chondrichthyans, the sharks and their relatives, which were the

It is perhaps because fishes live in a buoyant medium, whether it be fresh or sea water, that they show a diversity in body shapes that is unparalleled by other vertebrates. There is also a unique diversity in the modes of reproduction, whether by external or internal fertilization, and this, with the morphology and fine structure of the reproducti

Reproductive Biology of Teleost Fishes is the first integrated review of the reproductive biology of the bony fishes, which are the most species-rich and diversified group of vertebrates. Teleosts display remarkable variation in their modes of reproduction, and this volume is intended to provide a framework for understanding the remarkable reproductive diversity of this group. It describes their reproductive biology using, wherever possible, phylogenetic analyses and life-history theory as a means to interpret the information. The book addresses the genetic, physiological, behavioural, ecological, evolutionary and applied aspects of teleost reproduction in a comparative framework that emphasises the adaptive basis of reproductive diversity. Reproductive Biology of Teleost Fishes provides a comprehensive synthesis of fish reproduction that will be of great interest to life scientists, particularly ecologists, evolutionary biologists, physiologists and advanced undergraduates, postgraduates and research workers requiring a comprehensive overview of fish reproduction. The book is suitable for courses in fish biology and ecology, reproductive physiology and reproductive genetics. It also addresses applied questions and will be of value for courses on fisheries science and aquaculture. Libraries in all universities and research establishments where biological sciences, fisheries science and aquaculture are studied and taught should have several copies of this important book on their shelves.

There is remarkable diversity in the form and function of vertebrate reproductive mode, and adaptive explanations for the vast differences among species have fallen short. Instead, parent-offspring conflicts provide a parsimonious framework that describes why evolutionary transitions occur from one mode to another, and how the differences among species change the nature of sexual selection and speciation. My dissertation examines the effect of reproductive mode on vertebrate evolution by examining two topics--the evolution of matrotrophy following a transition from oviparity to viviparity and the effect differences in reproductive mode have the evolution of reproductive isolation and the rate of speciation. Cyprinodontiformes, an order of small mostly freshwater fish, are notable for exhibiting a wide range of reproductive phenotypes. I make use of the repeated transitions from oviparity to viviparity and from lecithotrophy to matrotrophy in Cyprinodontiformes to test hypotheses that parent-offspring conflicts have driven the evolution of reproductive mode.