The evolution of rice: Molecular vignettes on its origins and spread

The domesticated species Oryza sativa or Asian rice evolved starting approximately 9,000 years ago and from its centers of origin in China and India has subsequently spread throughout the Old World (and in historical times in the New World as well). This species is one of the key domesticated crop plants in the world and has emerged as a model for studying the origins and spread of domesticated taxa as well as in investigating the genetic basis for plant variation under domestication. Archaeological data has been critical in dissecting the origins and spread of rice throughout Asia, but molecular information has also provided a complementary approach to examining the evolutionary dynamics of this species. The evolutionary history of a species can leave its footprints within its genome. Moreover, genetic studies allow us to study the history of traits that do not leave an archaeological record-for example, grain stickiness or flowering time-which can provide insights into how crop species are adopted by different cultures. In this review, several molecular studies into the origin and spread of Asian rice are discussed and we explore the advances these genetic studies offer in our understanding of the evolution of domesticated species. We also explore how archaeological data can provide critical insights that can help refine genetic models of the origin and spread of domesticated species.