Molecular markers have opened exciting new windows through which to view the natural biological world. This treatment addresses the many applications for genetic markers (from polymorphic proteins and DNA) from the perspectives of population biology, behavioral ecology, organismal evolution, and phylogeny. Opening chapters review the history and purview of molecular approaches, and compare and contrast various laboratory techniques for revealing molecular markers. Subsequent chapters review the extensive scientific literature of molecular ecology and evolution, and describe a cornucopia of captivating discoveries about nature's workings, past and present. The book is taxonomically balanced with numerous examples from plants, animals, and microbes. It is also temporally balanced with examples ranging from assessments of genetic parentage and kinship in the most recent generations to phylogenetic assessments deep in the Tree of Life (and nearly everything in-between). This Second Edition of a seminal work (first published in 1994) brings the reader up-to-date on the many dramatic advances and insights made over the last decade. Furthermore, by retaining descriptions of many pioneering works, this book also traces the empirical and conceptual roots of each subject, and thereby provides a rich sense of the field's history. Appropriate for advanced undergraduates, graduate students, and scientists in such disciplines as ecology, genetics, population biology, ethology, molecular biology, systematics, and conservation biology, this new edition is for anyone interested in the application of molecular markers to organisms in the wild.