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The genetic structure of European mudminnow populations throughout the species range was examined using mitochondrial DNA and seven microsatellite loci. Ten mitochondrial haplotypes were detected, suggesting three phylogeographic lineages, which likely diverged during the Early and Middle Pleistocene. These three lineages geographically correspond to three regions: the Danube drainage including the Drava system and Dniester Delta, the Sava system and the Tisza system. High genetic diversity observed using mtDNA was confirmed with microsatellite data, suggesting the existence of 14 populations in the studied area. The isolation-with-migration model showed that migration rates between populations were generally low and were highest between the Drava and its tributary Mura. According to the inferred relative population splitting times, Umbra krameri likely spread from the eastern part of the species range to the west, which also showed the highest genetic diversity and largest population size. As reported by the time-calibrated phylogeny, separation of the European and American Umbra occurred roughly at the end of Late Cretaceous and in the first half of the Paleogene (60.57 Ma with 95% highest probability density of 39.57-81.75). Taking these results into account, appropriate guidelines are proposed to conserve European mudminnow populations. [ABSTRACT FROM AUTHOR]

We investigated diel habitat use of fish covering the littoral and pelagic zones of the Římov Reservoir (Czech Republic) and analyzed the influence of predator presence and of shifting feeding habitats in all dominant species and age groups. Our sampling revealed distinctive diel changes of fish distribution in the reservoir, which were age- and species-dependent. The overall abundance of subadult fish in littoral habitats was significantly higher at night than during the daytime. Subadults were almost absent in pelagic habitat during the day and their presence increased during the night, although densities were smaller than in the littoral. Adults preferred the pelagic zone during the day and partly migrated to the littoral at night. Potential fish predators were most likely responsible for small fish avoidance of the littoral and pelagic zones during day. Higher availability of food in the littoral was the most important driver of the high occurrence of subadults at night. Day preference of pelagic zone by adults is most likely caused by higher profitability of this habitat in comparison with littoral. The reasons for night inshore migration of adults are not obvious, but the homogenization of their distribution or resting in the littoral could explain such behavior. [ABSTRACT FROM AUTHOR]