Genetic structure of fragmented populations of a threatened endemic percid of the Rhône river: Zingel asper

Differential patterns of diversity at neutral and adaptive loci in endangered Rhodeus pseudosericeus populations

Given the fact that threatened species are often composed of isolated small populations, spatial continuity or demography of the populations may be major factors that have shaped the species' genetic diversity. Thus, neutral loci have been the most commonly-used markers in conservation genetics. However, the populations under the influence of different environmental factors may have evolved in response to different selective pressures, which cannot be fully reflected in neutral genetic variation. Rhodeus pseudosericeus, a bitterling species (Acheilognathidae; Cypriniformes) endemic to the Korean Peninsula, are only found in some limited areas of three rivers, Daecheon, Han and Muhan, that flow into the west coast. Here, we genotyped 24 microsatellite loci and two loci (DAB1 and DAB3) of MHC class II peptide-binding β1 domain for 222 individuals collected from seven populations. Our microsatellite analysis revealed distinctive differentiation between the populations of Daecheon and Muhan Rivers and the Han River populations, and populations were structured into two subgroups within the Han River. Apparent positive selection signatures were found in the peptide-binding residues (PBRs) of the MHC loci. The allelic distribution of MHC showed a degree of differentiation between the populations of Daecheon and Muhan Rivers and the Han River populations, partially similar to the results obtained for microsatellites, however showed rather complex patterns among populations in the Han River. Considering the apparent differences in the distribution of supertypes obtained based on the physicochemical differences induced by the polymorphisms of these PBRs, the differentiation in DAB1 between the two regional groups may result in the differences in immune function. No differentiation between these two regions was observed in the supertyping of DAB3, probably indicating that only DAB1 was associated with the response to locally specialized antigenic peptides.

High genetic diversity and population differentiation in Clarias gariepinus of Yala Swamp: evidence from mitochondrial DNA sequences

In order to improve the conservation and sustainable utilization of the African catfish Clarias gariepinus of the Yala Swamp in Kenya, genetic diversity and population structure of Lakes Kanyaboli and Namboyo populations of the species were studied using DNA sequences of the mitochondrial D-loop control region. Genetic diversity inferred as haplotype and nucleotide diversities and number of singletons and shared haplotypes was higher in the Lake Kanyaboli population (LKG) than the Lake Namboyo population (LNG) of C. gariepinus. Thirty-one haplotypes were inferred, of which 25 (80·6%) were private or singletons, while only six (19·4%) haplotypes were shared between LKG and LNG. Both populations were differentiated, with F_ST value that was significantly different from zero (P < 0·05). Two clusters were inferred both from the maximum likelihood tree and the spanning networks of phylogenetic relationships of haplotypes. Mismatch distribution for total sample was multi-modal but individually, distributions were uni-modal in LKG, but multimodal in LNG. The mean ± s.d. raggedness index for both populations was 0·085 ± 0·098 and not significantly different from zero (P > 0·05). Individual raggedness indices were 0·015 and 0·154 for LKG and LNG respectively. Fu's F_s was negative for both populations, with LKG recording -14·871, while LNG had -2·565, significantly different from zero for LKG (P < 0·05), but the value for LNG was not significant (P > 0·05). Tajima's D was negative for both populations, with LKG recording -1·734, while LNG had -1·136. Standardized square differences (SSD) were 0·001 for LKG and 0·048 for LNG and non-significant between them (P > 0·05). Values between all populations were also not significantly different (P > 0·05), mean ± s.d. SSD 0·025 ± 0·033.

Genetic diversity of the species Leporinus elongatus (Teleostei: Characiformes) in the Canoas Complex - Paranapanema River

Dams constructed along waterways interrupt the dispersion and migration of aquatic organisms, affecting mainly the abundance of migratory fish species. Translocation mechanisms have been constructed at dams aiming to minimize their impact on fish species migration behavior. There is little information available about the effect of the construction of dams on the genetic structure of the Neotropical migratory fish fauna. Therefore, RAPD molecular markers and microsatellites were utilized to evaluate the diversity and genetic structure of the migratory species Leporinus elongatus (piapara) in the Canoas Complex - Paranapanema River - Brazil. Ten groups were sampled in the fish ladders of the hydroelectric dam Canoas I and Canoas II during the reproductive period in three consecutive years. Both markers showed a high level of genetic diversity within these groups. The microsatellite markers demonstrated a loss of heterozygosity and a considerable level of inbreeding in the species. The genetic differentiation found among the groups with both markers utilized is within a range from low to moderate. The data obtained with the parameter of genetic diversity among the groups led to the conclusion that the groups of L. elongatus of the Canoas Complex are structured as a single population composed of sub-populations with low genetic diversity among them. The data on genetic diversity and population structure of L. elongatus are of great importance for the development of the species management and conservation programs in the Canoas Complex, which can also be utilized in aquaculture programs.

Environmental impacts of hydroelectric power and other anthropogenic developments on the hydromorphology and ecology of the Durance channel and the Etang de Berre, southeast France

The generation of electricity through hydropower can, along with other anthropogenic activities, degrade river hydromorphology and ecosystems. In this case, water for power generation is diverted from the River Durance to a canal, which services a chain of 17 power stations, with the lower three being in the catchment of the Etang de Berre. This means that excess water and sediments are discharged into the salt-water lagoon with enormous consequences for ecosystems there. This paper summarizes the impacts of HEP and other human activities on both the river and lagoonal systems. It also considers agency and government attempts to understand and counter the degradation of these systems, both to date and in the future, with the latter catering for the potential impacts of future human development and global warming.

Genetic structure of the vairone Telestes souffia in the eastern part of Lake Constance, central Europe

Examination of the genetic structure of the vairone Telestes souffia based on 10 nuclear markers (microsatellites) revealed little-to-moderate genetic differentiation between geographically adjacent populations in the eastern part of Lake Constance in central Europe. Results emphasize the critically endangered status of this freshwater fish in the upper Rhine River system.