GENETIC DIFFERENTIATION AND PHYLOGENETIC-RELATIONSHIPS AMONG GREEK SALMO-TRUTTA L (BROWN TROUT) POPULATIONS AS REVEALED BY RFLP ANALYSIS OFPCR AMPLIFIED MITOCHONDRIAL-DNA SEGMENTS

The genetic differentiation and phylogenetic relationships of 13 popul ations (11 from Greece, one from Albania and one from France) of brown trout (Salmo trutta L.) were investigated at the mtDNA level. RFLP an alysis of four segments of mitochondrial DNA (D-loop, cytochrome b and ND-5/6) amplified by PCR was used. Seven of 14 restriction endonuclea ses were found to detect variability in the ND-5/6 regions, whereas fo ur and two out of 17 and 16 were polymorphic in the D-loop and cytochr ome b, respectively. Eleven different haplotypes were observed. The ob served interpopulation diversity was very high (mean = 1.65 per cent), whereas the intrapopulation diversity was low in most cases (mean = 0 .063 per cent). Five phylogenetic assemblages were identified. The res ults demonstrate that Greece is one of the regions where brown trout d isplay very high levels of genetic diversity. Most populations were ge netically very distinct, possessing private mtDNA genotypes. Therefore , they represent unique gene pools which may warrant individual recogn ition for conservation and management. The genetic relationships among populations suggested by mtDNA data were not in accordance with alloz yme data. This study illustrates the importance of considering the his torical biogeography of a species in order to understand its populatio n genetic structure. It also reinforces the view that mtDNA analysis r epresents a powerful tool to study past and present demographic phenom ena.