Tree of heaven (Ailanthus altissima (Mill.) Swingle): Genetic imprints of geographic origin in Europe

Artikel aus einem Buch

17590BU

200205037

Tree of heaven (Ailanthus altissima (Mill.) Swingle), an invasive tree species, was introduced to Europe in the 18th century. It is a diploid, dioecious species, which reproduces both sexually and asexually. Early sexual maturity, prolific fruiting, ready germination, adaptability to infertile sites and rapid growth rate make A. altissima to an intensely spreading tree in the many countries where it has been introduced. At present, this tree grows throughout the majority of European countries. According to historical records, first seeds were sent from Peking to Paris in 1740´s by Pierre d’Incarville, a priest who travelled from South China to Peking in North China. The tree-of-heaven soon became a popular planted species also in other European cities because of its attractive foliage, the rapid growth, the tolerance to urban air pollution, and as forage for a silk-producing caterpillar of a moth Samia cynthia (Drury). Consequently cities became the place where the establishment and naturalisation of this tree species principally started. Here, we focus on A. altissima trees, collected mainly in large cities, of which we analysed patterns of genetic variation and structure in order to infer the geographic origin and dispersal patterns. Both nuclear DNA and plastid DNA were genotyped in 62 populations from 31 countries of trees planted/naturalised in botanical gardens, in urban parks, along roads and rivers. Most of the trees were assigned to six genetic clusters. Analyses of plastid haplotypes will be ready by the time of the presentation, with which we can estimate the geographic areas in China from which A. altissima was introduced to Europe. Final results will be a) discussed with respect to the geographic origin of studied trees and b) compared to studies on Ailanthus in Japan and the USA.