This volume from the Science 101 series addresses a broad spectrum of issues related to biodiversity. The first chapter defines the term and explores its evolution from the perspective of the biodiversity hierarchy, which organizes diversity from a genetic center out to the continental level. Tables are used to clarify certain aspects of biodiversity, such as estimated numbers of species, biomes and eco-regions, and major mass extinction events, while descriptions of scientific studies add interest: on the Galapagos Islands, for example, the first-born chick of the blue-footed boobie will sometimes push its sibling out of the nest, enhancing its own prospects of survival; when food is plentiful, however, the parent boobies suppress this pattern. What does this tell us about how environmental and behavioral factors combine to influence behavior? The second chapter looks at major geographic realms, the distribution of life around the planet and some early explorations, depicting stories of various scientific expeditions that led to the foundations of modern biology, including that of the HMS Beagle and Charles Darwin, the HMS Challenger (from which John Murray documented the discovery of more than 4,700 new marine species) and Alfred Russell Wallace’s observations of species distribution around the Malay Archipelago. Chapter Three delves into the importance of biodiversity—portraying the challenges that face so many species and ecosystems, such as the western honeybee, the Pacific kelp forests and the Monteverde Cloud Forest of Costa Rica, while also discussing the value of conservation efforts and how biodiversity can be used as a model for technological advancement. We learn, for example, that velcro was patterned after cockleburs, robot design has been aided by studies of millipedes and that an understanding of why bears don’t lose bone density during hibernation could lead to further discoveries in kidney disease or osteoporosis. The fourth chapter examines the state of the world’s biodiversity, delineating some of the major threats and underlying contributing factors such as habitat loss, weak legislation and lack of enforcement. The vast array of challenges is daunting—vanishing ice sheets, light pollution, toxic contaminants and habitat fragmentation, to list only a few. The volume closes on a hopeful note, with a final chapter that lists innovations in conservation efforts, from small changes people can make to increase sustainability and reduce their impact on biodiversity to more sweeping ideas for communities and businesses. Recommended for high school and public libraries.