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Allozyme variation in Chondrostoma from Austrian, French and northern Greek rivers was investigated. Populations of C. nasus from the upper Danube catchment are genetically very similar and apparently connected by high level of gene flow. Chondrostoma nasus has conserved all major allozyme polymorphisms during its recent range expansion into the Rhone basin. Chondrostoma vardarense from the Axios and Aliakmonas rivers share most of their allozymes with C. nasus from the upper Danube catchment, but have less genetic variation, a possible consequence of a genetic bottleneck following river capture.
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Gollmann et al. (2009) studied this question.
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