Molecular characterization of Alpine and northern european populations of Arctic charr Salvelinus alpinus (Linnaeus, 1758) by means of nuclear and mitochondrial markers

Molecular characterization of Alpine and Northern European populations of Arctic charr Salvelinus alpinus (Linnaeus, 1758) by means of nuclear and mitochondrial markers - The Arctic charr, Salvelinus alpinus, is a Holarctic Salmonid species adapted to cold-water habitats and whose either anadromous or sedentary populations are characterized by an extremely variable morphology. The presence of S. alpinus in Southern Europe is deemed as a relict of the Pleistocenic glaciations which strongly influenced both the distribution and the genetic variability of the species, due to repeated isolation and bottleneck events. Previous genetic studies revealed a very low mitochondrial diversity in contrast with the high genetic variability highlighted by microsatellites both within and between populations. In this study, mtDNA control region sequences and AFLP polymorphisms were characterized in 537 specimens from 35 Alpine and five Scandinavian populations. The control region data were aligned with GenBank sequences to build a Median-joining network. The results of AFLP analyses were evaluated by Factorial Correspondence Analysis (individual level) and by Multi-Dimensional-Scaling (population level), while hidden genetic structures were investigated by a Bayesian clustering approach. Multivariate statistical analyses showed that individuals and populations mostly clustered according to the geographic origin. Furthermore, some populations displayed low levels of genetic polymorphism which is probably due either to past demographic fluctuations or to a strong impact of anthropic activities in the recent decades.