About 99.9% of vertebrate species reproduce sexually. This makes the exceptional 0.1%—the asexual or clonal reproducers—fascinating in their own right, and also uniquely instructive about the biological significance of alternative reproductive modes. This book describes the genetics, ecology, natural history, and evolution of all of the world's approximately 100 “species” of vertebrate animal that routinely display one form or another of clonal or quasi-clonal reproduction. The book investigates the astounding realm of sexual abstinence, from the levels of DNA molecules and somatic cells to whole animals and natural populations. Also described is how scientists have learned to mimic and extend nature's own clonal processes by engineering perfect copies of genes, genomes, and whole animals in the laboratory. By considering the many facets of sexual abstinence and clonal reproduction in vertebrate animals, new light is also shed on the biological meaning and ramifications of standard sexuality.