A large scale survey of Populus nigra presence and genetic introgression from non-native poplars in Switzerland based on molecular identification

Populus nigra is considered a rare and threatened tree species in Switzerland because of dramatic habitat loss owing to river regulations during the last two centuries and because of potential. gene introgression from non-indigenous P deltoides through planted P x canadensis hybrids. The significance of introgression as an endangerment to P nigra, however, is controversial. The aims of the present study were (1) to assess how abundant P nigra trees are in Switzerland and (2) to assess potential gene introgression. We present data from a molecular survey of 1372 putative P nigra trees from Switzerland, using both chloroplast DNA and nuclear DNA markers. The results show that P nigra is more abundant in Switzerland than hitherto thought. Furthermore, we detected a tow frequency of gene introgression. (C) 2009 Elsevier GmbH. Att rights reserved.