Invasion Processes Of Eurasian Willows In Patagonia: Genetic Investigations.

BOZZI, J., MARCHELLI, P., AZPILICUETA, M.M., APARICIO, A., KLEINIG, L.K.; ZIEGENHAGEN, B; LEYER, I.; B.; GALLO, L

Congreso; Jornada de Jornadas de Salicáceas 2011 Tercer Congreso Internacional de Salicáceas en Argentina; 2011

Along the North-Patagonian rivers, the native Salix humboldtiana is affected by the dominance of invasive Salicaceae from the Salix alba-Salix fragilis complex, Salix babylonica and hybrids. In addition to the aggressive invasion of the exotic species, the native was selectively logged due to its high wood quality. It is therefore assumed a genetic impoverishment of the remaining patches both through a reduction in the effective population size and to the possible introgression with the exotic species. The aim of the genetic investigations in the German-Argentinean project is to provide insights into the interaction processes behind native and non-native Salicaceae with respect to genetic and evolutionary processes to predict the further trend of Salix invasions at the Rio Negro and the impact on S. humboldtiana populations. The objectives include: to assess the possibilities for natural hybridisation among native and non-native willows and determine the taxonomic status of invasive Salix species or hybrids, to evaluate the spatial organisation of genetic diversity of the native species and the invaded and to assess the threat to Salix humboldtiana by hybridisation and introgression. Interspecific hybridisation between Salix species occurring in Patagonian floodplains will be tested through diagnostic genetic markers. Gene flow, seed dispersal and/or vegetative spread will be estimated at local and regional scales. The regional scale includes Limay, Neuquén and Río Negro rivers, and the local scale will be located at one plot where regeneration occurs. Several plots are being sampled along the three rivers and molecular analyses are in progress to genotype the individuals with highly variable nuclear microsatellite markers. The results will provide a basis for willow management in Patagonia, which is in the focus of nature conservation authorities since the establishment of floodplain forests structured by invasive willows becomes a fast growing problem. River-floodplain ecosystems in Patagonia surrounded by the steppe ecosystem are considered to have a high potential as biodiversity resources, which will become more and more important under the expected raising temperatures and decreasing precipitation through climate change for the coming 80 years. Salix humboldtiana is a threatened species that urgently needs a conservation strategy, but it is also a highly used species with important economic perspectives. The possibility of easily propagate selected individuals allows the application of new genomic technologies which may bring valuable information for breeding and genetic rescue activities.