Genetic Heterogeneity Reveals On-Going Speciation and Cryptic Taxonomic Diversity of Stream-Dwelling Gudgeons (Teleostei, Cyprinidae) in the Middle Danubian Hydrosystem (Hungary)

Abstract

Although stream-dwelling gudgeons (Cyprinidae, genus: Gobio) are widespread in Central Europe, the taxonomy of this group and the distribution of its species are still unexplored in detail. The aims of our study are to ascertain taxonomic composition and distribution of the former Gobio gobio superspecies in the inner area of the Carpathian Basin. Since the presence of cryptic species is suspected in this area, we examined the taxonomic and phylogenetic relationships of Central European Gobio taxa by sequencing the mitochondrial DNA control region (mtCR). Additionally, we characterized the genetic structure of 27 stream-dwelling gudgeon populations of this area by Amplified Fragment Length Polymorphism (AFLP). Results of mtCR analysis proved the presence of three species already known as G. obtusirostris (dominant in NW-Hungary), G. gobio (sporadic) and G. carpathicus (sporadic). Additionally, the analysis revealed the existence of one doubtful taxon, G. sp1 (dominant in NE-Hungary), and a new isolated haplogroup (dominant in SW-Hungary). Although Network analysis showed significant detachment among haplogroups, their genetic distances were quite small. Therefore Bayesian phylogenetic analysis showed weak nodal support for the branching pattern both for newly described haplotypes, and for the already accepted species. AFLP data showed distinct population structure and a clear pattern of isolation was revealed by distance of stocks. At the same time, level of separation was not affected by the altitudinal position of sites. Moreover we found three major clusters of populations which were separated according to hydrographic regions, and corresponded to the findings of mtCR analysis. Our results suggest the on-going speciation of gudgeons in the Carpathian Basin, however the separation of haplogroups seems to only be an intermediate phase. The discovered natural pattern seems to be only slightly influenced by anthropogenic impacts. Additionally our results put into question the suitability of the recently accepted within Gobio genus taxonomy.

Austrian gudgeons of the genusGobio(Teleostei: Gobionidae): A mixture of divergent lineages

“…Whereas in the upper Danube system, all three main lineages are present, only G. gobio and Balkan lineage mtDNA haplotypes and G. obtusirostris and Balkan lineage haplotypes were found in the Rába and Mur river systems, respectively (Figure a). At least in the Rába river system, the apparent absence of the third mitochondrial lineage might be due to a small sample size ( N = 5), but our findings are consistent with Takács et al (), who did not find Balkan lineage haplotypes in the Rába system either (our Balkan lineage corresponds to haplogroup “B” in Takács et al, ). Both main RPS7 lineages were found in the upper Danube and Mur systems (Figure b).…”

“…Consequently, also the species status of G. obtusirostris still needs to be clarified. Nonetheless, for consistency with previous phylogenetic and phylogeographic studies on Gobio (Mendel et al, ; Takács et al, ), we decided to follow their terminology and use the term “ G. obtusirostris lineage.”…”

“…Molecular approaches have shed light on systematics, diversity, and phylogenetic relationships within the genus Gobio (Mendel et al, ; Takács et al, ), former sub‐species have been elevated to species rank and new species have been described (Doadrio & Madeira, ; Kottelat & Freyhof, ; Kottelat & Persat, ; Mousavi‐Sabet, Ganjbakhsh, Geiger & Freyhof, ; Naseka, Erkákan, & Kücük, ; Turan, Ekmekçi, Lusková, & Mendel, ; Vasiléva, Vasilév, & Boltachev, ). Phylogenetic and phylogeographic studies resolved systematic uncertainties (Mendel et al, ) and clarified thus far erroneous or incomplete local distribution patterns (Lusk, Halacka, Lusková, & Horák, ; Takács et al, ), information not only of scientific interest but also important for field biologists, consultants, and conservational workers. Thus, a large amount of molecular data on Gobio have accumulated over the last few years, not least because of large past and ongoing DNA barcoding initiatives (Geiger et al, ; Knebelsberger, Dunz, Neumann, & Geiger, ).…”

Introduced species community over-dominates endemic ichthyofauna of High Lika Plateau (Central Croatia) over a 100 year period

“…Cold climate (indicated by meteorological data in Table 1), slope and high altitude should promote life of cold adapted fish species and inhibit introduction of warm adapted species. Salmonids would find a favourable habitat for their dispersal no matter if appearing here naturally through drainage shifts (Takács et al 2014) or through historical human introduction.…”

“…Changes of the topographic and hydrographic conditions could cause these sub-areas to be shifted to another drainage (Takács et al 2014), leaving the possibility that Gacka, Lika and Jadova Rivers used to be in a direct contact with the Black Sea, and thus effectively explaining the appearance of the species. Furthermore, it should be taken into consideration that the samples collected with the latest research methods are fairly difficult to compare with those of the researches done many decades before.…”