Genetic differentiation of European grayling (Thymallus thymallus) populations in Serbia, based on mitochondrial and nuclear DNA analyses

Abstract

BackgroundThe structure and diversity of grayling (Thymallus thymallus) populations have been well studied in most of its native habitat; however the southernmost populations of the Balkan Peninsula remain largely unexplored. The purpose of this study was to assess the genetic diversity of Serbian grayling populations, detect the impact of stocking and provide guidelines for conservation and management.MethodsEighty grayling individuals were collected from four rivers (Ibar, Lim, Drina and Rzav). The mitochondrial DNA control region (CR; 595 bp of the 3'end and 74 bp of flanking tRNA) and the ATP6 gene (630 bp fragment) were sequenced for 20 individuals (five from each locality). In addition, all individuals were genotyped with 12 microsatellite loci. The diversity and structure of the populations as well as the recent and ancient population declines were studied using specialized software.ResultsWe detected three new haplotypes in the mtDNA CR and four haplotypes in the ATP6 gene of which three had not been described before. Previously, one CR haplotype and two ATP6 gene haplotypes had been identified as allochthonous, originating from Slovenia. Reconstruction of phylogenetic relations placed the remaining two CR haplotypes from the River Danube drainage of Serbia into a new clade, which is related to the previously described sister Slovenian clade. These two clades form a new Balkan clade. Microsatellite marker analysis showed that all four populations are genetically distinct from each other without any sign of intra-population structure, although stocking of the most diverse population (Drina River) was confirmed by mtDNA analysis. Recent and historical population declines of Serbian grayling do not differ from those of other European populations.ConclusionsOur study shows that (1) the Ibar, Lim and Drina Rivers grayling populations are genetically distinct from populations outside of Serbia and thus should be managed as native populations in spite of some introgression in the Drina River population and (2) the Rzav River population is not appropriate for further stocking activities since it originates from stocked Slovenian grayling. However, the Rzav River population does not represent an immediate danger to other populations because it is physically isolated from these.

Genetic variation of European grayling (Thymallus thymallus) populations in the Western Balkans

“…The other four haplotypes (i.e. Da23, Da25, Da27 and Da29) had been previously identified in the Danube drainage of Slovenia and Serbia (Weiss et al, 2002;Marić et al, 2011). In this study, the haplotypes Da23, Da25 and Ad7 were found to predominantly occur in Slovenia (frequency of 80-100%), while the others (i.e.…”

“…Additional grayling haplotypes from GenBank (accession numbers AF522395-AF522452; HM636922-HM636924) were used in analysis. To assign individual haplotypes and clades to the previously identified within the European grayling, data from this study were aligned against haplotypes from each clade (Weiss et al, 2002;Marić et al, 2011) and compared with them. T. arcticus (AF522453), T. grubei (AF522454) and T. brevirostris (AF522455) were used as outgroup taxa.…”

“…Unlike the Slovenian haplotypes, haplotypes found in BosniaHerzegovina and Montenegro (Da26, Da28, Da30, Da31, Da27, Da29 and Da32) form a rather homogenous group. Both sister groups belong to the so-called ''Balkan clade'' (Marić et al, 2011). Haplotype Da33 is the only haplotype found in the Danube drainage in the western Balkan that does not confine to the Balkan clade (Table 1).…”

“…A few local investigations (Kalamujić et al, 2007;Kalamujić, 2008;Marić et al, 2011) focused on grayling populations south of Slovenia. The preliminary results from these studies further affirm the assumption of Koskinen et al (2002c) that the level of genetic distinctiveness increases with approaching the southernmost border of the grayling range and underline the need to elaborate genetic surveys in this region.…”

Social, Economic, Fishery and Conservational Issues Featuring Fly Fishing Community in Serbia

“…trutta of two indigenous lineages sensu Bernatchez (2001): Danubian (Da) and Adriatic (Ad) in three drainages: Black Sea, Aegean Sea (Southern Serbia) and Adriatic Sea (South-western Serbia), as well as the Atlantic (At) brown trout introduced into the Da and Ad stocks. Serbia also homes a limited stock of European grayling Thymallus thymallus that belongs to the distinct Balkan lineage in the southernmost part of its dispersal area with only one isolated stock hitherto introduced there so far (Marić et al, 2011). In addition to the widespread brown trout mtDNA strains in both indigenous lineages, there are few narrowly distributed (Marić et al, 2006;Tošić et al, 2014).…”