-In order to illuminate the phylogeography of brown trout (Salmo trutta) populations in the Balkan state of Serbia, the 561 bp 5'-end of mtDNA control region of 101 individuals originating from upland tributaries of the Danubian, Aegean and Adriatic drainages were sequenced and compared to corresponding brown trout sequences obtained in previous studies. Among 15 haplotypes found, 14 were considered native, representing the Danubian and Adriatic lineages of the brown trout, while one haplotype (ATcs1), found only in two individuals originating from two stocked rivers, corresponded to the Atlantic lineage and was considered introduced. Native haplotypes exhibited a strong geographic pattern of distribution: the Danubian haplotypes were strictly confined to the Danubian drainage, while the Adriatic haplotypes dominated in the Aegean and Adriatic drainages; most of the total molecular variance (69%) was attributed to differences among the drainages. Phylogenetic reconstruction, supplemented with seven haplotypes newly described in this study, suggested a sister position of the Atlantic-Danubian and Adriatic-Mediterranean-marmoratus ("southern") phylogenetic group, and pointed to the existence of a distinct clade, detected within the "southern" group. The data obtained confirmed our expectation of the existence of high genetic diversity in Balkan trout populations, and we recommend more widespread surveys covering trout stocks from the region.phylogeography / Salmo trutta / mitochondrial DNA / control region / Balkan Peninsula

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The brown trout (Salmo trutta L.) is widely distributed all around Europe but its natural diversity is 19 threatened by massive stocking with Atlantic domestic strains. Describing the remaining natural genetic 20 diversity and the proportion of domestic hatchery strains in rivers is a prerequisite for smart conservation. 21 The high genetic diversity of brown trout populations around the Tyrrhenian Sea is well known. Use of 22 twelve microsatellites has allowed description of the natural genetic structure of populations and detection 23 of the consequences of stocking. Mitochondrial DNA control region sequences and the LDH-C1* gene 24 enabled placement of each population into one of the six mitochondrial and two allozymic known 25 2 evolutionary lineages. The Corsican populations showed low intra-population genetic diversity but an 26 exceptionally high level of inter-population differentiation. More southern Tyrrhenian regions exhibited 27 opposite pattern of diversity, partly due to the Atlantic domestic introgression. Globally, the natural 28 structure outlines two north-south clines: high inter-population differentiation and predominance of the 29 Adriatic lineage in the north, but lower inter-population differentiation and presence of the natural Atlantic 30 lineage in the south. In addition, the Tyrrhenian region is the contact zone between the widespread 31 Adriatic lineage and a local natural Atlantic lineage probably coming from North Africa through the Strait 32 of Gibraltar.

We evaluate the hypothesis of no geographic structure in the Huchen (Hucho hucho), a large, predatory salmonid endemic to the Danube basin. Forty-seven individuals sampled from throughout the Huchen's native range were genetically characterized. Extremely limited sequence diversity across 1,800 bases of mtDNA (the complete control region and partial NADH-1 subunit) evidenced by four closely related mtDNA haplotypes was found. Nonetheless, the geographic distribution of mtDNA repeats (5-10, 82-bp long copies per individual) as well as allelic diversity across two microsatellite loci indicated large-scale geographic structure between the north-western (Austria and Slovenia) distribution area and eastern (Slovakia and Ukraine) or southern (Bosnia-Herzegovina and Montenegro) sample sites. An extremely slow rate of substitution for the H. hucho mtDNA is considered along with the alternative hypotheses to explain the limited mtDNA diversity. Considering the regional genetic structure implied by our data, we advocate restrictions on the transport of brood fish or yearlings across the range of the species distribution and sale of Huchen across international boundaries. Future genetic analysis to support local conservation and monitoring efforts must focus on developing a high-resolution screen that may be applied to identify hatchery versus naturally reproduced individuals in the wild.

To determine the genetic architecture of trout in Albania, 87 individuals were collected from 19 riverine and lacustrine sites in Albania, FYROM and Greece. All individuals were analyzed for sequence variation in the mtDNA control region. Among fourteen haplotypes detected, four previously unpublished haplotypes, bearing a close relationship to haplotypes of the Adriatic and marmoratus lineages of Salmo trutta, were revealed. Ten previously described haplotypes, characteristic of S. ohridanus, S. letnica and the Adriatic and Mediterranean lineages of S. trutta, were also detected. Haplotypes detected in this study were placed in a well supported branch of S. ohridanus, and a cluster of Mediterranean – Adriatic – marmoratus haplotypes, which were further delimited into three subdivisions of Mediterranean, marmoratus, and a previously non-described formation of four Adriatic haplotypes (Balkan cluster). Haplotypes of the Balkan cluster and the other Adriatic haplotypes, do not represent a contiguous haplotype lineage and appear not to be closely related, indicating independent arrivals into the Adriatic drainage and suggesting successive colonization events. Despite the presence of marmoratus haplotypes in Albania, no marbled phenotype was found, confirming previously reported findings that there is no association between this phenotype and marmoratus haplotypes.