Another myth busted?

In the past year, BTRG has performed a comprehensive genetic analysis of dentex trout from the River Neretva. This time we applied an extended set of molecular markers and included for comparison several specimens of "real glavatica" (i.e., marmorated trout from the Neretva), which were badly missing in our preliminary study.

Contrary to our previous hypothesis, dentex trout turned out as genetically indistinct from marmorated trout of the Neretva. We assume that a phenotype characteristic of dentex trout had probably evolved as a consequence of specific local adaptation.

For more information, see the summary of already submitted manuscript below.

The dentex samples were provided by prof. Branko Glamuzina (University of Dubrovnik) and prof. Ivan Bogut (University of Osijek), and the "glavatica" samples by Naris Pojskić (Institute for Genetic Engineering and Biotechnology).

Summary

The Balkan Peninsula is home to the most diverse collection of salmonids in the world. Nevertheless, many taxonomic uncertainties remain unresolved despite over a century of studies. Conservation of Balkan salmonid biodiversity hinges in large part upon addressing such uncertainties and is therefore of paramount importance. A notable example is found in the enigmatic Salmo dentex, which has been described by various authors in discontinuous populations ranging from the Aoos river in Greece to the Krka river drainage in Croatia. Current reports suggest it has disappeared from much of its previous range. At present, several contradictory opinions predominate on the taxonomic status of S. dentex without any broad consensus. To help resolve this issue we performed a rigorous molecular genetic analysis using a robust array of mtDNA, microsatellite, and nuclear gene markers of so-called S. dentex of the lower Neretva river drainage alongside other co-inhabiting endemic salmonids (i.e. S. obtusirostris, S. marmoratus, S. trutta). Our results clearly showed three genetically distinct lineages of salmonids with S. dentex being phenotypically distinct yet genetically indistinct from S. marmoratus of the lower Neretva. Based on our results and previous molecular results on Montenegrin dentex, it is clear that S. dentex is not a monophyletic lineage and should not be considered a distinct species on a genetic basis. We hypothesize S. dentex to most likely be polyphyletic assemblage of fish sharing a similar life history and unified phenotype evolved as a consequence of specific local adaptation.