The invasion of ecosystems by alien species is a key driver of global environmental change and many invasive plant species attain sufficiently high abundance to alter the structure and function of an ecosystem. This book is the first publication to explain the reasons as to why some alien species undergo a profound shift in their ecological fortune from being minor components of their native ecosystems to becoming devastating dominants of non-native habitats.The book assesses the ecological, morphological, functional and genetic factors that contribute to invasion success. Cutting-edge tools in molecular genetics in the past two decades have opened up additional avenues for ecologists to address such questions and obtain novel insights in the ecology of invasive species. This text also highlights which molecular approaches are especially useful in discriminating between native and non-native populations of invaders that cannot otherwise be differentiated based on morphological traits. Such molecular approaches can yield useful insights with potential implications for biodiversity managers to identify alien invasive species that are likely to become invaders in the near future, thereby prioritizing them accordingly for different management strategies.