Population Differentiation in Common Walnut (Juglans regia L.) across Major Parts of Its Native Range-Insights from Molecular and Morphometric Data.

Juglans regia is an economically highly important species for fruit and wood production in the warm temperate and subtropical zones of the Northern Hemisphere. Besides the natural influence of climatic and geomorphological barriers, its genetic structure has been strongly modified by humans and the population history is still unclear. For this reason, we investigated mainly natural walnut populations across the Eurasian continent on a molecular (44 populations, 581 trees) and morphometric level (23 populations, 1391 ripe nuts).