Impact of introduced willows on the genetic diversity of Salix humboldtiana of north patagonia.

BOZZI, J.; MARCHELLI, P; THOMAS, L.; BIRGIT ZIEGENHAGEN; LEYER, I; GALLO, L.A.

Mar del Plata

Congreso; BIOLIEF 2ndWorld Conference on Biological Invasions and Ecosystem Functioning,; 2011

BIOLIEF

Casual or intentional exotic species introductions may initiate an invasion process that can produce important modifications in the genetic diversity of invaded native species. Demo-genetics processes like fragmentation, bottlenecks, hybridization and introgression tend to diminish and/or dilute their genetic variation and vital elements of the genetic system like mating system, gene flow, and fitness can be modified. Along the Río Negro River (635 km and 1000 m3/sec) in North Patagonia, Argentina, the native species Salix humboldtiana is affected by the invasion of introduced willow clones of the complex Salix alba-Salix fragilis, and Salix babylonica. The presence of dams, agricultural activities and selective extraction of the native willow species contribute to the landscape modification. A total of 1236 Salix humboldtiana adult trees were collected in 42 populations covering the lower valleys of Neuquen and Limay rivers and the upper, middle and lower valley of Rio Negro river. Natural regeneration was sampled at 14 populations summing 1344 individuals in Neuquén and Río Negro rivers. Two Salix humboldtiana diagnostic SSR markers have been found which are useful to hybrid detection. A high-throughput sequencing of S. humboldtiana genome allowed the search for other polymorphic SSRs. A strong fragmentation and reduction in population size was associated to the intensity of landscape use. Natural hybridization with the introduced clones is very likely and introgression processes should not be discarded. The complexity of this riparian system highlights its relevance as a study case to test genetic hypothesis related to invasion process dynamics in forest tree species.