Historical demography and spatial genetic structure of the subterranean rodent C tenomys magellanicus in T ierra del F uego ( A rgentina)

C tenomys (tuco‐tuco) is the most numerous genus of S outh A merican subterranean rodents and one of the most genetically diverse clades of mammals known. In particular, the genus constitutes a very interesting model for evolutionary studies of genetic divergence and conservation. C tenomys magellanicus is the southernmost species of the group and the only one living in I sla G rande de T ierra del F uego ( A rgentina). This species presents two chromosomal forms ( C m 34 and C m 36) fragmented into demes distributed from the north region (steppe) to the south region (ecotone) of the island, respectively; no hybrids or overlapping areas were detected. To study the historical demography and the spatial genetic structure of the C . magellanicus population we used mitochondrial DNA (mtDNA) (D‐loop and c ytochrome b ) and microsatellite loci. Nine mtDNA haplotypes were identified, three of them belonging to the north and the other six to the south. Shared haplotypes between regions were not detected. mt DNA and microsatellite genotypes showed a marked pattern of population structure with low values of genetic flow between regions. The south is made up of small populations or isolated demes making up an endogamic metapopulation with unique alleles and haplotypes. Also, the results suggest a northward expansion process starting from an ancestral haplotype from the south. That population might have lived at a refuge through the adverse P leistocene environmental conditions that took place at T ierra del F uego. Results of this study are relevant to the conservation of C . magellanicus , suggesting that each region (north and south) might be considered as an Evolutionarily Significant Unit. © 2013 The Linnean Society of London