A comprehensive account of taxonomy, including historical overviews, the first cladistic analyses of bacteria based on classical evidence, the most comprehensive cladistic analyses of eukaryotes based on classical evidence, cladograms, tables and lists, descriptions of the various groups, profiles of taxonomists, and coverage of classifications for lower groups, evolution, and fossils, with edits and a chapter on ecology and biogeography and one on geological time added for this 2nd edition.