Genetic variability in tench (Tinca tinca L.) as revealed by PCR-RFLP analysis of mithochondrial DNA

Four mitochondrial DNA segments, ND1, ND6, cyt b and D-loop, were analysed by polymerase chain reaction-restriction fragment lenght polymorphism (PCR-RFLP) in 14 tench (Tinca tinca L.) populations located in Europe and Asia; also data on five Italian populations previously analysed for the same mtDNA segments were included in the study. All the considered segments were polymorphic and originated a total of 9 composite haplotypes, which were clustered into two haplogroups, A and B, possibly corresponding to the Western and Eastern phylogroups previously described in tench. Nine out of 19 populations showed polymorphism, with haplotype diversity ranging from 0.246 to 0.643 and nucleotide diversity from 0.009 to 0.078. Seventy-five percent of the pairwise comparisons were significant, indicating a high between-population variability. The Neighbour-Joining tree revealed the presence of three clusters, including ‘pure’ populations, with only A or B haplogroup, and ‘mixed’ populations, with both haplogroups. The possibility of identifying populations with different haplotypes has practical implications for both conservation and supportive stocking.