Once per life cycle, mitotic nuclear divisions are replaced by meiosis I and II – reducing chromosome number from the diploid level to a haploid genome and recombining chromosome arms by crossing-over. In animals, all this happens during formation of eggs and sperm – in yeasts before spore formation. The mechanisms of reciprocal exchange at crossover/chiasma sites are central to mainstream meiosis. To initiate the meiotic exchange of DNA, surgical cuts are made as a form of calculated damage that subsequently is repaired by homologous recombination. These key events are accompanied by ancillary provisions at the level of chromatin organization, sister chromatid cohesion and differential centromere connectivity. Great progress has been made in recent years in our understanding of these mechanisms. Questions still open primarily concern the placement of and mutual coordination between neighboring crossover events. Of overlapping significance, this book features two comprehensive treatises of enzymes involved in meiotic recombination, as well as the historical conceptualization of meiotic phenomena from genetical experiments. More specifically, these mechanisms are addressed in yeasts as unicellular model eukaryotes. Furthermore, evolutionary subjects related to meiosis are treated.

Since George Gaylord Simpson published Tempo and Mode in Evolution in 1944, discoveries in paleontology and genetics have abounded. This volume brings together the findings and insights of today's leading experts in the study of evolution, including Ayala, W. Ford Doolittle, and Stephen Jay Gould. The volume examines early cellular evolution, explores changes in the tempo of evolution between the Precambrian and Phanerozoic periods, and reconstructs the Cambrian evolutionary burst. Long-neglected despite Darwin's interest in it, species extinction is discussed in detail. Although the absence of data kept Simpson from exploring human evolution in his book, the current volume covers morphological and genetic changes in human populations, contradicting the popular claim that all modern humans descend from a single woman. This book discusses the role of molecular clocks, the results of evolution in 12 populations of Escherichia coli propagated for 10,000 generations, a physical map of Drosophila chromosomes, and evidence for "hitchhiking" by mutations.

In addition, the author develops new insights, especially in his examination of the intricate relationships between parasites and their social hosts through the rigorous use of evolutionary and ecological concepts.".

The Arthur M. Sackler Colloquia of the National Academy of Sciences address scientific topics of broad and current interest, cutting across the boundaries of traditional disciplines. Each year, four or five such colloquia are scheduled, typically two days in length and international in scope. Colloquia are organized by a member of the Academy, often with the assistance of an organizing committee, and feature presentations by leading scientists in the field and discussions with a hundred or more researchers with an interest in the topic. Colloquia presentations are recorded and posted on the National Academy of Sciences Sackler colloquia website and published on CD-ROM. These Colloquia are made possible by a generous gift from Mrs. Jill Sackler, in memory of her husband, Arthur M. Sackler.

Using an interdisciplinary approach, the authors provide an adaptionist interpretation of the basic features of recombination, its evolutionary significance as a key process in reproduction and its importance in genetic mapping. The book synthesizes much recent information in the fields of evloutionary genetics of recombination, the analysis of genetic markers and breeding applications. The authors analyse recombination through a consideration of computer models, large Drosophila populations and an empirical approach to current theories. Practically-orientated readers will be interested in the discussion of a wide spectrum of mapping methods and the new algorithms proposed for genetic mapping of quantitative loci.

This book assesses the scientific value and merit of research on human genetic differencesâ€"including a collection of DNA samples that represents the whole of human genetic diversityâ€"and the ethical, organizational, and policy issues surrounding such research. Evaluating Human Genetic Diversity discusses the potential uses of such collection, such as providing insight into human evolution and origins and serving as a springboard for important medical research. It also addresses issues of confidentiality and individual privacy for participants in genetic diversity research studies.