"Molecular ecology is a field of study that integrates molecular biology, genetics, ecology, and evolutionary biology to help us understand some of the many ways in which organisms interact with each other and with their environment. Over the past few decades, new techniques in molecular biology have allowed us to generate genetic data from an incredibly wide range of taxa. These data have revolutionized our understanding of ecology and evolution through investigations that include quantifying genetic diversity, retracing the routes that individuals follow across short and long distances, identifying cryptic species, reconstructing family relationships, inferring demographic processes such as population declines, and identifying genes that enable evolutionary adaptations. Many of these topics have important real-world applications, for example in conservation genetics we might ask which populations have levels of genetic diversity that are low enough to justify human intervention, and in studies of biological invasions we might use genetic data to identify the origin - and potentially the introduction route - of an invader"-- Provided by publisher.