Genetic variation among trout in the River Neretva basin, Bosnia and Herzegovina

Abstract

Mitochondrial DNA haplotypes, characteristic of the Adriatic, Danubian and Atlantic lineages of brown trout Salmo trutta and of Salmo obtusirostris were found in trout inhabiting the River Neretva basin. With the exception of the one associated with softmouth trout, haplotypes were not correlated with operational taxonomic units based on phenotype. Nuclear DNA analysis identified four genetic assemblages corresponding to S. obtusirostris, different geographically confined autochthonous S. trutta populations, introduced S. trutta and a genetically heterogeneous group located between S. obtusirostris and S. trutta in the dendrogram of individuals, indicating the existence of hybrid swarms in the Neretva basin. Genetic assemblages corresponding to Salmo marmoratus and the recently proposed Salmo cf. montenigrinus were not detected. The presence of genetic intermediates indicates that the studied taxa are not completely reproductively isolated and that genetic stability has been either anthropogenically interrupted or not yet achieved among Neretva trout. This finding should be considered in management decisions since such an unstable community must be particularly susceptible to breakdown in genetic population structure as a result of hybridization between native and nonnative introduced trout stocks.

Application of mtDNA markers for European huchen (Hucho hucho Linnaeus, 1758) management in Poland

“…It should be emphasized that one of the most important factors determining the efficiency of conservation management of endangered fish species is the origin and quality of stocking material. Baseline genetic data are essential during welldeveloped restitution programs, enabling proper identification and selection of stocking material for supplementing wild populations, originating from proper stocks, being characterized by a high level of genetic diversity (Razpet et al 2007;Snoj et al 2009). Therefore, studies on the genetic structure of stock or population are crucial for conservation management of endangered fish species protected by a rehabilitation measure, such as European huchen.…”

Resolving taxonomic uncertainties using molecular systematics: Salmo dentex and the Balkan trout community

“…3), it is evident that the overlapping between brown trout and dentex refer mainly to these hybrid individuals. Additionally, the common haplotype AdN, found in high frequencies in all trouts of the lower Neretva course (Table 1, the softmouth trout excluded), has been previously reported to prevail in the native brown trout in the upper Neretva, too (Razpet et al, 2007). It is likely, therefore, that AdN is the ancestral haplotype in the Neretva basin, and as such cannot be conclusive indicator in assessing the relationship between brown trout, marble trout, and dentex.…”

“…Taking into account this observation and considering also the fact that the genetic signature of the Atlantic brown trout was found in the Neretva basin but not in the Skadar basin, made us consider that a great portion of phenotypic variability in the lower course of the Neretva could be attributed to introgression with nonindigenous domesticated brown trout. The non-native Atlantic brown trout and their introgressive hybridization with native trouts has already been observed in the managed area in the upper Neretva, giving rise to a multitude of phenotypic forms which may distort characteristic features and complicate attempts at phenotypic classification (Razpet et al, 2007). It is likely, on the other hand, that the absence of nonnative trout in the Skadar basin has sustained the reproductive barriers between native salmonid assemblages and therefore retained their genetic and phenotypic integrity.…”

“…The number of groups in STRUCTURE was estimated by calculating the likelihood of obtaining the data assuming a model in which the sampled individuals represented from 1 to 10 groups (K = 1-10), each repeated 12 times. In addition, the number of groups was determined also using ad hoc Razpet et al (2007) statistic DK (see Evanno et al, 2005). For each simulated run the first 20.000 steps were discarded (burn-in) and followed by 100.000 MCMC replicates.…”

“…Thirty-one randomly chosen samples from all phenotype groups were genotyped by sequencing while the remaining ones were genotyped using RFLP analysis described in Razpet et al (2007).…”