Genetic Diversity of Brown Trout Populations Using Mitochondrial Markers In Relatively Similar Geographical and Ecological Conditions – a Carpathian Case Study

Among the species of salmonids that exist in Romania, the most common is the brown trout (Salmo trutta, morpha fario, Linnaeus, 1758), with a high commercial potential, being used for aquaculture or fishing. Unfortunately, its natural habitat is disrupted by human activities and in order to avoid local extinction of Salmo trutta fario repopulation strategies are being applied. The repopulation activities must be carefully designed and conducted taking into consideration that there is a high risk of hybridization. Our study aims to analyze the genetic diversity of three Romanian brown trout populations found in rivers in the Făgăraş Mountains using mitochondrial markers.

Standard DNA extraction protocol with phenol-chloroform was applied to the biological material represented by small fin fragments sampled from 80 individuals of brown trout, followed by PCR amplification of D-loop control region and Sanger sequencing. Alignment and editing of all the sequences obtained were carried out with Bioedit, the phylogenetic tree construction was performed by Neighbour Joining method implemented in MEGA v5, and intra- and interpopulational diversity was evaluated with DNAsp v5 and MEGA v5.

For the three brown trout populations, 13 haplotypes were identified for N1, 11 for N2 and 10 for N4, with a haplotype diversity greater than 0.8. The phylogenetic tree topology showed that individuals chosen for this study were placed in the Danubian clade as the other Danubian sequences selected from GenBank.

The study proved that the three Salmo trutta fario populations analyzed were genetically distinct and that in Romania there are still are pure Danubian brown trout populations.