Spatial genetic variability and molecular ecology of the invasive Castor canadensis in Tierra del Fuego

FASANELLA MARIANA; LIZARRALDE MARTA SUSANA

Congreso; 2nd World Conference on Biological Invasions and Ecosystem Functioning; 2011

The Archipelago of Tierra del Fuego (ATDF) contains numerous invasive species, of which Castor canadensis is the most abundant and important invasion. Beaver are responsible for the most drastic landscape alteration in Tierra del Fuego since the last glacial age, affecting not only the hydrology and composition of the southern beech forest, but more importantly allowing other exotic species to invade the ecosystem. From 25 pairs intentionally released in 1946, beavers have increased their numbers to a current population size of 100.000 individuals. 222 samples were analyzed and we detected 7 D-loop haplotypes, of which 3 are the most abundant and are distributed all along the archipelago. We subdivided the ATDF population into five subpopulations and we found a slight structure, Fst =0.169. In addition, there were no barriers to gene flow within the Isla Grande (IG), which may be due to the complex river system that allows beavers to easily disperse. These results indicate that the IG is a single management unit. Successful eradication programs of mammals always were conducted in small islands however, populations on larger islands or those that display no distinct structure are more problematic, so the eradication of Castor canadensis in the ATDF would be logistically impossible. Therefore, we propose to control the IG populations and to eradicate populations of the adjacent islands and especially from the continent. If the species is not early removed in the mainland, beavers will begin to colonize the Patagonian woods very quickly and its eradication will be almost impossible.