BACKGROUND: Anthropogenic factors can have a major impact on the contemporary distribution of intraspecific genetic diversity. Many freshwater fishes have finely structured and locally adapted populations, but their natural genetic structure can be affected by river engineering schemes across river basins, fish transfers in aquaculture industry and conservation management. The European bitterling (Rhodeus amarus) is a small fish that is a brood parasite of freshwater mussels and is widespread across continental Europe. Its range recently expanded, following sharp declines in the 1970s and 1980s. We investigated its genetic variability and spatial structure at the centre of its distribution at the boundary of three watersheds, testing the role of natural and anthropogenic factors in its genetic structure. RESULTS: Sequences of mitochondrial cytochrome B (CYTB) revealed that bitterling colonised central Europe from two Ponto-Caspian refugia, which partly defines its contemporary genetic structure. Twelve polymorphic microsatellite loci revealed pronounced interpopulation differentiation, with significant small-scale differentiation within the same river basins. At a large scale, populations from the Baltic Sea watershed (middle Oder and Vistula basins) were distinct from those from the Black Sea watershed (Danube basin), while populations from rivers of the North Sea watershed (Rhine, Elbe) originated from the admixture of both original sources. Notable exceptions demonstrated the potential role of human translocations across watersheds, with the upper River Oder (Baltic watershed) inhabited by fish from the Danube basin (Black Sea watershed) and a population in the southern part of the River Elbe (North Sea watershed) basin possessing a signal of admixture from the Danube basin. CONCLUSIONS: Hydrography and physical barriers to dispersal are only partly reflected in the genetic structure of the European bitterling at the intersection of three major watersheds in central Europe. Drainage boundaries have been obscured by human-mediated translocations, likely related to common carp, Cyprinus carpio, cultivation and game-fish management. Despite these translocations, populations of bitterling are significantly structured by genetic drift, possibly reinforced by its low dispersal ability. Overall, the impact of anthropogenic factors on the genetic structure of the bitterling populations in central Europe is limited.

• Keywords
• Cryptic invasions, Freshwater conservation, Game fish stocking, Gene flow, Human-mediated translocation, Phylogeography, Population genetics,
• MeSH
• Bayes Theorem MeSH
• Species Specificity MeSH
• Gene Frequency genetics   MeSH
• Genetic Variation MeSH
• Carps genetics   MeSH
• Humans MeSH
• Microsatellite Repeats genetics   MeSH
• DNA, Mitochondrial genetics   MeSH
• Mitochondria genetics   MeSH
• Genetics, Population MeSH
• Rivers * MeSH
• Fresh Water MeSH
• Geography MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Europe MeSH
• North Sea MeSH
• Names of Substances
• DNA, Mitochondrial MeSH

The natural history of model organisms is often overlooked despite its importance to correctly interpret the outcome of laboratory studies. Ageing is particularly understudied in natural populations. To address this gap, we present lifetime demographic data from wild populations of an annual species, the turquoise killifish, Nothobranchius furzeri, a model species in ageing research, and two other species of coexisting annual killifishes. Annual killifish hatch synchronously, have non-overlapping generations, and reproduce daily after reaching sexual maturity. Data from 13 isolated savanna pools in southern Mozambique demonstrate that the pools supporting killifish populations desiccated 1-4 months after their filling, though some pools persisted longer. Declines in population size over the season were stronger than predicted, because they exceeded the effect of steady habitat shrinking on population density that, contrary to the prediction, decreased. Populations of N. furzeri also became more female-biased with progressing season suggesting that males had lower survival. Nothobranchius community composition did not significantly vary across the season. Our data clearly demonstrate that natural populations of N. furzeri and its congeners suffer strong mortality throughout their lives, with apparent selective disappearance (condition-dependent mortality) at the individual level. This represents selective force that can shape the evolution of lifespan, and its variation across populations, beyond the effects of the gradient in habitat persistence.

• MeSH
• Cyprinodontiformes * genetics   physiology   MeSH
• Longevity MeSH
• Ecosystem MeSH
• Population Density MeSH
• Longitudinal Studies MeSH
• Sex Ratio MeSH
• Population Dynamics MeSH
• Seasons MeSH
• Sympatry MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH