The aim of the monographs is to foster effective intra- and interdisciplinary communication between geneticists, and plant and animal breeders. This is to be achieved by publishing authoritative up-to-date texts; concise, but at the same time comprehensive, monographs, and multiauthor volumes on theoretical and applied genetics. The following broad fields of genetics and breeding are within the scope of the series: Evolutionary genetics Developmental genetics Population genetics Biochemical genetics Ecological genetics Somatic cell genetics Biometrical genetics Agricultural genetics Cytogenetics Mutation breeding Radiation genetics Breeding methodology Acceptable subjects for the Monographs on Theoretical and Applied Genetics are basic and applied aspects of genetic variation; genetic resources; genetic exchange and reproduction; mutagenesis; genotype-environment interaction; gene structure, regulation, action, expression and interaction; chromosomal and extrachromosomal inheritance of economic traits, and genetic models and simulations. September 1975 The Editors Preface Meiotic configurations are looked at from a special point of view in this book: the extraction from them of the maximal amount of quantitative information of genetic interest. Although this requires a certain understanding of their origin and consequences, much of what is known about chromosomes and their for mation into the special structures collected under the rather indiscriminate term I "configuration", is not considered relevant for this purpose, and simply neglected.

Meiosis, the process of forming gametes in preparation for sexual reproduction, has long been a focus of intense study. Meiosis has been studied at the cytological, genetic, molecular and cellular levels. Studies in model systems have revealed common underlying mechanisms while in parallel, studies in diverse organisms have revealed the incredible variation in meiotic mechanisms. This book brings together many of the diverse strands of investigation into this fascinating and challenging field of biology.

Introduction When the study of heredity and variation first came to be treated as a scientific subject-and this, one must remember, was only just over a hundred years ago-there was an unfortunate separation between the disciplines of cytology and experimental breeding. This separation was based partly on a lack of understanding and partly on a lack of the desire to understand. Even WILLIAM BATESON, the first apostle of mendelism in England, had a blind spot for cytology and for many years dogmatically refused to believe that MENDEL'S determinants were transmitted and distributed by the chromosomes. This separation between cytology and experimental breeding is one which persists, in a measure, even today, simply because there are two quite different, though complementary, techniques available for the study of heredity and variation. On the one hand, one can study directly the structure and behaviour of the actual vehicles which transmit the genetic determinants from one generation to the next. This is the method employed by those who study genetics through a microscope. The alternative method is that used by the experimental breeder who, in default of being able to watch the hereditary factors segregate from each other directly, is obliged to examine the constitution of the germ cells indirectly by sampling, and usually at random, the products of a controlled mating.

The chromosome complement (karyotype) often differs between related mammalian species (including humans vs chimpanzees), such that evolutionary biologists muse whether chromosomal difference is a cause or a consequence of speciation. The common shrew is an excellent model to investigate this problem because of its many geographical races (potential species) differing chromosomally, and its several sibling species (recently speciated forms) that are also chromosomally different. This system is an exceptional opportunity to investigate the role of chromosomes in speciation and this volume reflects detailed research following these approaches. Highlights include the demonstration that chromosomal re-arrangements can be associated with complete loss of gene flow and thus speciation and that selection within species hybrid zones may lead to de-speciation rather than speciation. This book represents an extraordinarily detailed consideration of the role of chromosomes in speciation in one astonishing species, providing insights to those interested in mammalian diversity, chromosomal evolution and speciation.

This two-volume work surveys the entire range of general aspects of chromosome research on plants. This first volume is divided into two sections. Section A consists of 11 chapters covering the entire range of general aspects of chromosome research in plants (including a chapter on genetic engineering in crop improvement). Section B is devoted to cytogenetics of cereals and millets (wheat, rye, barley, triticale, oats, maize, rice, pearl millet, and minor millets). More than one chapter is devoted to the same crop to give a detailed treatment of chromosome research (including molecular biology) in these crops.The second volume deals with cytogenetics of plant materials including legumes, vegetable and oil crops, sugar crops, forage crops, fibre crops, medicinal crops and ornamentals. This work will be useful both as a reference work and a teaching aid to satisfy a wide range of workers. Every chapter has been written by an expert who has been involved in chromosome research on a particular plant material for many years.

Wheat, which is the second most important cereal crop in the world, is being grown in a wide range of climates over an area of about 228 945 thou sand ha with a production of about 535 842 MT in the world. Bread wheat (Triticum aestivum L. ) accounts for 80% of the wheat consumption, howe ver, it is attacked by a large number of pests and pathogens; rusts and smuts cause enormous damage to the crop and reduce the yield drastically in some areas. The major breeding objectives for wheat include grain yield, earliness, resistance to lodging and diseases, spikelet fertility, cold tolerance, leaf duration and net assimilation rate, fertilizer utilization, coleoptile length, nutritional value, organoleptic qualities, and the improvement of charac ters such as color and milling yield. The breeding of wheat by traditional methods has been practiced for centuries, however, it has only now come to a stage where these methods are insufficient to make any further breakthrough or to cope with the world's demand. Although numerous varieties are released every year around the world, they do not last long, and long-term objectives cannot be realized unless more genetic variability is generated. Moreover, the intro duction of exotic genetic stocks and their cultivation over large areas results in the depletion and loss of the native germplasm pool.