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In the last 20 years, new species, asexual reproduction, polyploidy and hybridization have all been reported within the genus Cobitis. An understanding of the current distribution and baseline phylogeographical history of ‘true’ nonhybrid Cobitis species is crucial in order to unravel these discoveries. In the present work, we investigated the phylogeography of the spined loach, Cobitis taenia, using 1126 bp of the mitochondrial cytochrome b gene from 174 individuals collected at 47 sites. In total, 51 haplotypes that differed at 49 positions (4.35%) were detected. We deduce that C. taenia survived European glaciations in at least three refuges in the Ponto-Caspian area. Two of these refuges each provided a major lineage that recolonized Europe in separate directions: one westward to England and the other spreading north into Russia before moving west. A third (minor) lineage that contributed little to the recolonization of Europe was also revealed — remaining near its Black Sea refuge. However, more recent history was difficult to resolve with colonization from a more western refugium during the last glacial maximum (LGM) a distinct possibility. Nested clade analysis indicates a pattern of restricted gene flow with isolation by distance at the first two levels and overall. Unlike many other European freshwater fish species, the Danube is not part of the current distribution of C. taenia, nor was it used as either a refuge or a source of colonization of Europe. Low genetic diversity within C. taenia suggests that its colonization of Europe is relatively recent. Demographic analyses revealed a history of recent expansion and isolation by distance. [ABSTRACT FROM AUTHOR]

The substratum preferences of spined loach from eastern England differed significantly between fish of different age groups, sexes, habitat origin (river or drainage ditches) and even between ditches, under experimental conditions. Spined loach from drainage ditches preferred organic sediments, while those from a river showed more variable substratum choice. Significant inter-individual differences were found in river fish, with juveniles preferring sand, while males preferred organic sediment and females gravel. In addition, these preferences often changed at night. A clear pattern of nocturnal behaviour was established. These results have implications for conservation management since the identification of habitat requirements is often based on diurnal distributions.

The chromosomes of spiny loach specimens, genus Cobitis, from three populations in England were examined using Giemsa staining, Ag-NOR, C-banding and CMA3 techniques. All individuals examined invariably had a diploid chromosome number 2n=48 and a karyotype composed of ten metacentric, eighteen submetacentric and twenty subtelo-acrocentric chromosomes. The results revealed that only C. taenia occurred in the northern part of the Cobitis distribution range. Various cytogenetic features such as the number and location of Ag-NORs, DNA sites rich in GC pairs, and C bands confirmed the taxonomic status of the specimens. Among the individuals from English populations no polyploid forms have been detected.