ORIGINAL PAPER Assessing genetic variation and population structure of invasive North American beaver (Castor Canadensis Kuhl, 1820) in Tierra Del Fuego (Argentina) Marta Susana Lizarralde Æ Graciela Bailliet Æ Sebastia ´n Poljak Æ Mariana Fasanella Æ Cecilia Giulivi Received: 8 August 2007 / Accepted: 10 August 2007 Ó Springer Science+Business Media B.V. 2007 Abstract The North American beaver (Castor Canadensis) was introduced into Isla Grande de Tierra del Fuego, Argentina in 1946 as a potential source of wild fur. The species showed high growth potential, reaching close to 100,000 individuals from an original founding stock of 25 females and 25 males. Beavers adapted rapidly to their new environ- ment and became invasive, providing an excellent model of successful adaptation of introduced popu- lations to a new habitat. In this study, we used polymorphic mitochondrial (mt) DNA to evaluate genetic variation in the introduced beaver population from Tierra del Fuego. Nucleotide variation in partial sequences of Cytochrome b (500 bp) and 12S rRNA (421 bp) genes and the main non-coding D-loop region (521 bp) were analyzed. Our study allowed to identify 10 different mtDNA lineages in the invasive population, none of them shared among the source populations. The pattern observed is a consequence of cessation of gene flow following expansion of the founding beaver population since the time of its introduction. This approach contributes to the under- standing of effects of genetic changes on survival ability and reproductive success of invasive species. It also has important management implications to invasive species. Keywords Castor Canadensis Á Control region Á Cytochrome b Á D-loop Á Genetic variation Á Haplotype Á Invasive population Á Mitochondrial marker Á 12S rRNA Á Tierra del Fuego Introduction The management of biological invasions requires establishing general principles to predict the perfor- mance of a species in a new locality. Consideration of population genetics, with explicit analyses of the genetic structure of invasive species, may allow more effective management of invasive species. Examples of potential applications of population genetics in studies of invasive species include predicting inva- siveness to reduce occurrence of new invasions, M. S. Lizarralde (&) Á S. Poljak Á M. Fasanella Centro Regional de Estudios Geno ´micos, Universidad Nacional de La Plata, Av. Calchaquı ´ km 23.5 Piso 4, CP 1888 Florencio Varela, Buenos Aires, Argentina e-mail: mlizarralde@creg.org.ar M. S. Lizarralde Á S. Poljak Centro Austral de Investigaciones Cientı ´ficas, CADIC- CONICET, Ushuaia 9410 Tierra del Fuego, Argentina G. Bailliet Instituto Multidisciplinario de Biologı ´a Celular, IMBICE, La Plata 1900, Argentina C. Giulivi Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA 123 Biol Invasions DOI 10.1007/s10530-007-9161-6