The population and genetic profiles of a remnant Vimba vimba population in the upper course of the River Dyje (N=48°53 ́18 ́ ́/ E=15°39 ́29 ́ ́) was carried out to provide a basis for conservation measures. This population is an isolated fragment of a more widespread population in this river system and is now declining. It came into being 60 years ago as a consequence of the construction of the Vranov dam in the middle section of the River Dyje. Over those 60 years V. vimba disappeared from the other localities of the River Dyje basin. In the population under study, vimba is a single-batch spawner involving two age groups of fishes (4 to 5 years of the age). Individuals over six years of age are rare and sporadically occurring fishes of 8 to 10 years are exclusively females. The size of the adult part of population is less than one thousand individuals. The length growth rate is relatively high as compared with other studied populations in the Czech Republic, fishes of five years attain 200 mm of Sl. A very low genetic variability was evidenced in the population (mean number of alleles per locus = 1.30 ± 0.1; percentage of polymorphic loci = 16.7 %; mean observed heterozygosity = 0.022 ± 0.011).
Karyotyped specimens from three populations of spined loaches, genus Cobitis, that occurred in the Veleka (Bulgaria), Chernaya (Crimean Peninsula) and Southern Bug (Ukraine) Rivers in north-western Pontic region were subjected to enzyme electrophoresis (for 5 loci), comparative morphological studies, and phylogenetic analysis (based on PCR of a 1230 bp fragment of mtDNA and the cytochrome b gene). These studies resulted in the description of loaches from the Crimean Peninsula as a new species Cobitis taurica, while the taxonomic status of populations from the Veleka and S. Bug rivers appeared to be controversial and in need of further investigation.
Using mitochondrial DNA (mtDNA) variations, the phylogenetic position of Croatian populations of spined loaches within the European genus Cobitis was assessed. Spined loaches from the Matica, Neretva, Cetina, Zrmanja, Jadova, Sava, Drava and Kupa Rivers are included in two previously described groups: a) Cobitis sensu stricto group, and b) Adriatic group. The Danubian populations of C. elongatoides and its hybrids from the Kupa and Drava Rivers are related to the species included in the Cobitis s. str. group, whereas all other analysed populations clustered within the Adriatic group, which is divided into the “Bilineata”, “Elongata” and “Ohridana-zanandreai” clades. The Croatian spined loaches from the Adriatic watershed are included in the first two clades. Four mitochondrial lineages were revealed within the “Bilineata” clade: 1. ”C. bilineata” lineage containing loaches from the Zrmanja River and Italian and Spanish representatives of C. bilineata; 2. “Neretva-Cetina” lineage included loaches from the Cetina River (C. dalmatina) and the Neretva River (C. narentana); 3. “Jadova” lineage included specimens from the Jadova River; and 4. “Matica” lineage comprised spined loaches from the Matica River. Cobitis elongata from the Kupa and Drava Rivers belonged to the “Elongata” clade with two sublineages. Allozyme analyses of the C. taenia complex revealed the presence of both C. elongatoides and its all-female triploid hybrids in the Danube basin of Croatia.
Sample of Gobio gobio from 30 localities in the Czech Republic and Slovak Republic were studied. Starch gel electrophoresis was used for evaluation of variability of allozyme patterns in 16 active protein systems comprising 26 loci. Products of 17 loci were considered to study the genetic structure of its populations. From this, genetic variability was found in ten loci, occurrence of rare alleles was detected in next four loci. Percentage of polymorphic loci ranged between 6 and 41%; mean occurrence of alleles was between 1.1 and 2.0 per locus; and mean heterozygosity was observed at 0.013 to 0.248. The genetic distances among populations were 0.002 to 0.175 (N e i 1972) and 0.063 to 0.385 (C a v a l l i - S f o r z a & E d w a r d s 1967). Differences in occurrence and frequencies of alleles in some loci among the sea basins were evident. Higher genetic variability identified in populations from the Danube river system (Black See basin) is probably connected with the fact that this basin served as a refuge for ichthyofauna during glaciations.