TY - JOUR T1 - Ancient Humans Influenced the Current Spatial Genetic Structure of Common Walnut Populations in Asia JF - PLOS ONE Y1 - 2015 A1 - Pollegioni, Paola A1 - Woeste, Keith E. A1 - Chiocchini, Francesca A1 - Del Lungo, Stefano A1 - Olimpieri, Irene A1 - Tortolano, Virginia A1 - Clark, Jo A1 - Hemery, Gabriel E. A1 - Mapelli, Sergio A1 - Malvolti, Maria Emilia ED - Chaubey, Gyaneshwer AB -

Common walnut (Juglans regia L) is an economically important species cultivated worldwide for its wood and nuts. It is generally accepted that J. regia survived and grew spontaneously in almost completely isolated stands in its Asian native range after the Last Glacial Maximum. Despite its natural geographic isolation, J. regia evolved over many centuries under the influence of human management and exploitation. We evaluated the hypothesis that the current distribution of natural genetic resources of common walnut in Asia is, at least in part, the product of ancient anthropogenic dispersal, human cultural interactions, and afforestation. Genetic analysis combined with ethno-linguistic and historical data indicated that ancient trade routes such as the Persian Royal Road and Silk Road enabled long-distance dispersal of J. regia from Iran and Trans-Caucasus to Central Asia, and from Western to Eastern China. Ancient commerce also disrupted the local spatial genetic structure of autochthonous walnut populations between Tashkent and Samarkand (Central-Eastern Uzbekistan), where the northern and central routes of the Northern Silk Road converged. A significant association between ancient language phyla and the genetic structure of walnut populations is reported even after adjustment for geographic distances that could have affected both walnut gene flow and human commerce over the centuries. Beyond the economic importance of common walnut, our study delineates an alternative approach for understanding how the genetic resources of long-lived perennial tree species may be affected by the interaction of geography and human history.

VL - 10 SP - e0135980 UR - http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0135980 CP - 9 J1 - PLoS ONE ID - AZ-CF-182725 M3 - 10.1371/journal.pone.0135980 ER -