Molecular Phylogeography of the Tench Tinca Tinca (Linnaeus, 1758)
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Univerzita Karlova v Praze Přírodovědecká fakulta Katedra zoologie Molekulární fylogeografie lína obecného Tinca tinca (Linnaeus, 1758) Zdeněk Lajbner Disertační práce Školitel: RNDr. Petr Kotlík, Ph.D. ÚŽFG AV ČR, v.v.i., Liběchov Praha 2010 D DD 6 #$%%tiky & ()*+,5 D D. % a s 0 6D D z jeho strany dostávalo. D#1% .20 %\ 4. T% $$. () +,54.D0D$ TT 0 T "T 0 a cenné rady. , TD D \ .0 T .D tvorby di 60 T T ?\\0 D , D DD D 8 0#6$9 D"0$ 5 republiky - 6 4:;<;=>" "0 D\TD"0 6 #$% % $+ D5 .$- 6 +,;?@;A@;@B@TD0 # D Univerzity Karlovy v Praze - 6 CB<C;DCD( D$.T 0$E6 F $5 "0GD00- 6 <;;=<<@D;H1 % % $ () +,5- $6 ;@ICC;DIB> Summary The tench Tinca tinca (Linnaeus, 1758) is a valued table fish native to Europe and Asia, but which is now widely distributed in many temperate freshwater regions of the world as the result of human-mediated translocations. Spatial genetic analysis applied to sequence data from four unlinked loci (three nuclear introns and mitochondrial DNA) defined two groups of populations that were little structured geographically but were significantly differentiated from each other, and it identified locations of major genetic breaks, which were concordant across genes and were driven by distributions of two major phylogroups. This pattern most reasonably reflects isolation in two principal glacial refugia and subsequent range expansions, with the Eastern and Western phylogroups remaining largely allopatric throughout the tench range. However, this phylogeographic variation was also present in European cultured breeds studied and some populations at the western edge of the native range contained the Eastern phylogroup. Thus, natural processes have played an important role in structuring tench populations, but human-aided dispersal have also contributed significantly, with the admixed genetic composition of cultured breeds most likely contributing to the introgression. We have then designed novel PCR-RFLP assays of two nuclear-encoded markers and one mitochondrial DNA (mtDNA) marker, which allow a rapid identification of the morphologically undistinguishable Western and Eastern phylogroup and also of three geographical mtDNA clades within the Eastern phylogroup. The method will enable researchers and also fishery practitioners to rapidly distinguish genetically divergent geographical populations of the tench and will be useful for monitoring the introduction and human-mediated spread of the phylogroups in wild populations, for characterization of cultured strains and in breeding experiments. The population genetic test based on analyses of variation at introns of nuclear genes, microsatellites, allozymes and mitochondrial DNA in populations from two postglacial lakes within the contact zone of both phylogroups did not detect robust linkage and Hardy-Weinberg disequilibria that would not be limited to individual loci and would be concordant between populations. This test, based on the expectation that in the presence of strong barriers to reproduction the hybrid populations would show genome-wide associations among alleles and genotypes, supports the hypothesis of free interbreeding between the two phylogroups of tench. Therefore, although the phylogroups may be considered as separate phylogenetic species, the present data suggest that they form a single species under the biological species concepts.