GENETIC-VARIABILITY WITHIN AND AMONG SYMPATRIC BROWN TROUT (SALMO-TRUTTA) POPULATIONS - MULTILOCUS DNA FINGERPRINT ANALYSIS

Three brown trout (Salmo trutta L.) morphotypes, sonaghen, gillaroo, and ferox have been described from Lough Melvin, Ireland. Previous isozyme studies have shown these to be three genetically distinct and reproductively isolated populations. Multi-locus DNA fingerprinting of these populations was carried out to provide an initial assessment of this technique's potential use for salmonid population genetic studies. Highly variable profiles of Pal I digested genomic DNA were revealed for all three populations, using the human minisatellite 33.6 hybridization probe. Band-sharing analysis concurred with previous isozyme studies in showing a lower level of genetic variability within the ferox as compared with sonaghen and gillaroo. The analysis also confirmed the genetic distinctness of each population. While no unambiguous diagnostic fragments were observed for any of the populations, it was possible to discriminate ferox from both sonaghen and gillaroo based on the higher mean band-sharing coefficient observed within ferox. The main value for multi-locus DNA fingerprinting in salmonid population genetic studies may be as an alternative rapid method of determining overall levels of genetic variability (heterozygosity).