Molecular phylogeographic analyses of the loach Oxynoemacheilus bureschi reveal post‐glacial range extensions across the Balkans

Abstract

Rivers on the Balkan Peninsula can be separated into ichthyofaunistic areas with different endemic fish species. The Vardar River contains a particularly large number of endemics, indicating its complete and long-term isolation from neighbouring river systems. One of the few species shared with other rivers is the loach species Oxynoemacheilus bureschi. In this study, the genetic analyses of 175 individuals of O. bureschi from 17 sites, covering the entire distribution of the species, including the Rivers Vardar (= Axios), Struma (= Strymon), Mesta (= Nestos) and Danube, were performed using one mitochondrial and one nuclear marker. Genetic differentiation among populations was in general low. Shared haplotypes were common and occurred even between distant localities and different river systems. This points to a high degree of gene flow among populations and rejects the hypothesis that the population in the Vardar River represents a relict from an early colonization of the Balkan Peninsula. In contrast, the results suggest that populations in the Vardar River, as well as those in the Danube River, are of recent origin, and a human-mediated introduction cannot be excluded. On the other hand, the populations in the Aggitis River, a left tributary of the lower Struma River, were clearly separated from the rest of the species and represent a long-term isolated lineage. Demographic analyses suggest a recent population expansion for O. bureschi, in which the population in the Aggitis River was not involved.

DNA barcoding and species delimitation of the genus Oxynoemacheilus (Teleostei: Nemacheilidae) in Anatolia

“…Through the analysis of mitochondrial cyt b and nuclear S7 sequences, Šedivá et al . (2010) indicated that maximum intraspecific K2P distances based on cyt b (0.90) were proposed for population structure of O. bureschi . In the present study, the intraspecific p distance calculated based on COI (0.98) was greater than those of cyt b.…”

Fresh- and Brackish-Water Cold-Tolerant Species of Southern Europe: Migrants from the Paratethys That Colonized the Arctic

“…On the other hand, several genera of this subfamily occur in Western Asia [45], and two members of the genus Oxynoemacheilus Banarescu and Nalbant, 1966 even reached the Balkan Peninsula waterbodies [46]. Another genus, Turcinoemacheilus Banarescu and Nalbant, 1964, is distributed mainly in the basins of the Tigris and Euphrates rivers, but one member of this genus, T. himalaya, has been described from Nepal [47].…”

“…According to Prokofiev [44] (p. 286), the westward spread of the nemacheiline loaches took place during the early Neogene sea regression, when "the Tethys-Parathetys basin lost its connection with the Indian Ocean". Probably, large-scale phylogenetic studies of this group of fish would help to solve this question more precisely, but genetic studies of the Nemacheilinae in Western Asia and Europe have so far dealt only with interspecific differences [48] and the short-distance dispersal of representatives of some genera [46].…”