The Theory Of Sex Allocation Mpb 18 Volume 18

This book is the first comprehensive treatment of sex allocation from the standpoint of modern evolutionary theory. It shows how the determination of sex ratio, resource allocation to sperm versus egg within simultaneous hermaphroditism, and the evolution of sex reversal can he explained as examples of a single process. The genetical theory, developed mostly with graphical arguments, also specifies when hermaphroditism and dioecy are themselves evolutionary stable. The work balances theory with field and laboratory research, providing critical tests of the theory by empirical studies of sex ratio in parasitoid wasps and mites, sex reversal in shrimp and coral reef fish, and allocation of resources to pollen versus seeds in higher plants. In addition, the author oilers an encyclopedic review of the field and laboratory work of other scientists, reviews many as yet untested hypotheses in sex allocation, and points toward numerous plant and animal systems that hold promise for future tests.

Advances in the Study of Behavior was initiated over 40 years ago to serve the increasing number of scientists engaged in the study of animal behavior. That number is still expanding. This volume makes another important "contribution to the development of the field" by presenting theoretical ideas and research to those studying animal behavior and to their colleagues in neighboring fields. Initiated over 40 years ago to serve the increasing number of scientists engaged in the study of animal behavior Makes another important contribution to the development of the field Presents theoretical ideas and research to those studying animal behavior and to their colleagues in neighboring fields

This book deals with a key area of population genetics: the ratio of the sexes in a population, or the allocation of resources to male versus female reproductive function. Samuel Karlin and Sabin Lessard establish the formal theoretical aspects of the evolution of sex ratio within the constraints of genetic mechanisms of sex determination. Their results generalize and unify existing work on the topic, strengthening previous conceptions in some cases and, in other instances, offering new directions of research. There are two main approaches to understanding the causes and effects of sex ratio. One approach focuses on the optimization and adaptive functions of sex allocation, while the other emphasizes the consequences of genetic sex determination mechanisms. In discussing the utility of these two approaches, Professors Karlin and Lessard examine the principal sex-determining mechanisms and facts involved in sex ratio representations, the various genetic and environmental factors that contribute to adaptive sex expression, and the evolution of sex determining systems and controls. From a population genetic perspective, the authors derive evolutionary properties in support of the high incidence of 1:1 sex ratio in natural populations and investigate the conditions that can explain the occurrence of biased sex ratio.

"Ecosystem" is an intuitively appealing concept to most ecologists, but, in spite of its widespread use, the term remains diffuse and ambiguous. The authors of this book argue that previous attempts to define the concept have been derived from particular viewpoints to the exclusion of others equally possible. They offer instead a more general line of thought based on hierarchy theory. Their contribution should help to counteract the present separation of subdisciplines in ecology and to bring functional and population/community ecologists closer to a common approach. Developed as a way of understanding highly complex organized systems, hierarchy theory has at its center the idea that organization results from differences in process rates. To the authors the theory suggests an objective way of decomposing ecosystems into their component parts. The results thus obtained offer a rewarding method for integrating various schools of ecology.

Ever since the acorn woodpecker was observed and described by Spanish explorers, its behavior--particularly the unique habit of caching acorns in specialized storage trees or granaries--has impressed observers. Acorn woodpeckers are also one of the few temperate zone species in which young are reared communally in family groups. This demographic study investigates the complexities of acorn storage and group living in acorn woodpeckers at Hastings Reservation in central coastal California. It is one of the most thorough studies of any avian social system to date.

A common tendency in the field of population ecology has been to overlook individual differences by treating populations as homogeneous units; conversely, in behavioral ecology the tendency has been to concentrate on how individual behavior is shaped by evolutionary forces, but not on how this behavior affects population dynamics. Adam Lomnicki and others aim to remedy this one-sidedness by showing that the overall dynamical behavior of populations must ultimately be understood in terms of the behavior of individuals. Professor Lomnicki's wide-ranging presentation of this approach includes simple mathematical models aimed at describing both the origin and consequences of individual variation among plants and animals. The author contends that further progress in population ecology will require taking into account individual differences other than sex, age, and taxonomic affiliation--unequal access to resources, for instance. Population ecologists who adopt this viewpoint may discover new answers to classical questions of population ecology. Partly because it uses a variety of examples from many taxonomic groups, this work will appeal not only to population ecologists but to ecologists in general.

Florida Scrub Jays are an excellent example of a cooperative-breeding species, in which adult birds often help raise offspring not their own. For more than a decade Glen E. Woolfenden and John W. Fitzpatrick studied a marked population of these birds in an attempt to establish a demographic base for understanding the phenomenon of "helping at the nest." By studying both population biology and behavior, the authors found that habitat restraints, rather than kin selection, are the main source of the behavior of Florida Scrub Jays: the goal of increasing the number of close relatives other than descendants in future generations is of relatively minor importance in their cooperative-breeding behavior. The Florida Scrub Jay lives only in the Florida oak scrub. All acceptable habitat is constantly filled with breeders. Each year about half of the pairs are assisted by one to several nonbreeding helpers. This book provides extensive data on fecundity, survivorship, relatedness, and dispersal to establish the demographic milieu and to address questions arising out of observed helping behavior--whom, how, when, and why the helpers help.