CURRENT SPATIAL GENETIC STRUCTURE OF COMMON WALNUT (JUGLANS REGIA L.) POPULATIONS ACROSS ASIAN RANGE

Landscape genetics is an emerging powerful approach that combines methods from landscape ecology, geography, population genetics to quantify the effects of landscape on evolutionary processes. In particular, the landscape genetic overlay approach for geographic coincidence, genetic discontinuities and GIS technologies has provided opportunities to analyze spatial patterns of genetic diversity in forest species. Common walnut (Juglans regia L.) is generally accepted as native to the mountain ranges of south-eastern Europe and west-central Asia, from Xinjiang, Kyrgyzstan, Uzbekistan, mountains of Nepal, Tibet, north India and Pakistan, through Afghanistan, Turkmenistan and Iran to the Caucasus. The distribution of J. regia has been strongly modified by human management during the last 3,000 years. Despite its economic importance and the interest in germplasm conservation, the genetic diversity of J. regia has been investigated primarily on a national or regional scale. Despite the impressive morphological and phenological variation of walnut in Central Asia, an accurate overview of the wild genetic resources of the species in the Asian native range has never been undertaken.