Conservation of the Earth's diversity is one of the most important and daunting challenges faced by biologists and politicians alike. But exactly what (and why) we are trying to conserve remains a complicated and divisive question. This collection of essays features a diverse roster of internationally recognized experts who exemplify the wide range of views regarding how biodiversity should be defined--in terms of species numbers, categorization of landforms, different ecological levels, and as a dynamic and socio-political necessity for our own survival. In providing a synthesis of systematics and conservation, the book addresses problems such as matching species numbers, variety, and the systematic hierarchy assigned to geographic areas. In addition, the book outlines methods for selecting priority areas for conservation while challenging the concepts of "megadiversity" and "hotspots". Ecologists, taxonomists, conservation biologists, geographic information service managers, and those working for monitoring and land use organizations will want to read this book.