Mitochondrial DNA diversity in Atherina boyeri populations as determined by RFLP analysis of three mtDNA segments.

The genetic differentiation and the phylogenetic relationships of eight Atherina boyeri Greek populations have been investigated at the mtDNA level. The populations studied are from two different lakes, a lagoon, the interface zone between the lagoon and the sea, and four marine sites. RFLP analysis of three mtDNA segments (12s rRNA, 16s rRNA and D-loop) amplified by PCR was used. Six, seven and eight restriction enzymes were found to have at least one recognition site at 12s rRNA, 16s rRNA and D-loop respectively. Twenty-one different haplotypes were detected among the populations studied. Several restriction patterns were revealed. These patterns can be used for the discrimination of the populations living in the sea ('marine' type populations) from the others inhabiting the lagoon and the lakes ('lagoon' type populations). The estimated net nucleotide sequence divergence between the populations examined ranged from 0 to 10.385%, while the Nst value of 0.92 indicates the existence of high interpopulation genetic differentiation. This high degree of differentiation detected between the 'lagoon' and 'marine' type populations makes the classification of these two types of populations as a single taxon questionable.