A landscape genetics approach was applied to common goby (Pomatoschistus microps) sampled from three estuaries (six sites) of the Portuguese coast. Individuals of each site were genotyped for eight microsatellite loci and levels of genetic diversity and differentiation were correlated to present-day estuarine characteristics and historical events. A general ecological state for each sampling site was obtained from a principal component analysis (PCA) applied to estuarine geomorphologic characteristics and levels of heavy metals and total polycyclic aromatic hydrocarbons contamination. Genetic diversity was higher than that previously reported for common goby in the Atlantic and Mediterranean. FST were generally very low (0.000-0.049), as well as Nei’s genetic distances (0.000-0.167), although the later were statistically significant. Estuarine geomorphology and heavy metal contamination contributed the most to estuarine ecological differentiation but no trend was detected in the relationship between these characteristics and samples’ genetic diversity. Mantel tests also revealed no significant relationships between geographic, genetic and ecological distances. Null alleles only contributed to explain significant Hardy-Weinberg departures in two of the eight loci scored, although disequilibria were detected in at least two loci per sample. Notwithstanding its exploratory character, results suggest an important role for historical factors in the timing and direction of P. microps colonization of the Portuguese estuaries. Environmental variation and P. microps ability to cope with it are also structuring factors in establishing and maintaining the patchy genetic diversity detected in the studied estuaries.
The hexaploid barbel population of the species Labeobarbus fritschi
which lives in the Allal El Fassi dam reservoir in the north of Morocco showed an absence of males among a sample of 597 individuals analyzed in a first survey and among the 39 fish analyzed in this study. A possible explanation is that this population may be composed of females only and that
they reproduce either by gynogenesis or hybridogenesis, two processes triggered by hybridization with a sexually incompatible species (possibly the
sympatric barbel Luciobarbus setivimensis in this case). We used molecular markers to collect any information that could explain the phenomenon. To do this, numerous nuclear loci were screened (more than 50) in search of polymorphism. Genetic diversity was low as a possible consequence of clonal reproduction: only three allozymic and two intronic loci presented a sufficient level of polymorphism to be exploited. The existence of several copies of the same multilocus genotypes (1/3 of the fish) – with some showing a significantprobability of not being derived from sexual reproduction – provided evidence of unisexual reproduction. Deviations from panmixia as well as linkage equilibrium were also observed. Although preliminary, the data supports the hypothesis of the unisexual reproduction of females by way of gynogenesis rather than hybridogenesis.
Two sedentary gobiids (the cryptic species Pomatoschistus microps and P. marmoratus) have been analysed in several Mediterranean lagoons of southern France and in Corsica. In order to determine the level of population isolation between neighbouring lagoons, mtDNA was screened using RFLP (7 endonucleases) of an amplified 2 kb region (including the D-loop and Cyt b). The mtDNA diversity of the genus is high (42 haplotypes for 125 individuals) so that a detailed haplotype tree has been constructed using two additional outgroup species. The main result is that almost no common haplotypes are shared between populations of the same species inhabiting neighbouring lagoons. A high level of isolation between neighbouring lagoons during several centuries is deduced, at least for P. microps populations.
The short-finned eel Anguilla bicolor is known to be subdivided in two distinct subspecies (i.e. A. bicolor bicolor and A. bicolor pacifica), each subspecies being geographically distributed in allopatry. The present survey intends to describe genetic differentiation, population structure, molecular variance and phylogeny of both subspecies of A. bicolor in Indonesian waters. The genotypes of seven microsatellite locus and sequences of the entire cytochrome b were analyzed on 180 specimens collected in 10 representative locations, where one of the two subspecies spend their freshwater life. The results showed high heterozygosity (0.767 < He < 0.891). Significant deviation from Hardy-Weinberg equilibrium were essentially detected on AjTR04 and Aro63 loci. No diagnostic microsatellite loci was observed between the subspecies which shared most of their alleles. Genetic Reynolds distances computed for each population ranged
between 0.029 and 0.073 among A. bicolor pacifica populations, between 0.045 and 0.149 among A. bicolor bicolor populations and between 0.042 and 0.114 among populations of different subspecies. Both the mitochondrial and the microsatellite markers confirm the subdivision into two subspecies while microsatellite loci suggest a moderate differentiation between subspecies.
Three rheophilic species of the western Palaearctic Barbus with adjacent geographic distributions are recognised in the Danube River basin, each diagnosed by a set of unique mitochondrial DNA alleles. Barbus petenyi Heckel, 1852 from the Eastern and Southern Carpathians and from the Stara Planina Mts is redescribed and a neotype is designated. Barbus carpathicus, new species, is distributed in the Western and Eastern Carpathians. Barbus balcanicus, new species, occurs in the Dinaric and Western Stara Planina Mts. The three species are morphologically similar to each other but B. balcanicus can be distinguished by subtle differences in the snout shape and body and fin colour pattern. As evident from genetic data the name B. cyclolepis waleckii Rolik, 1970 was proposed for the hybrids between B. barbus and B. carpathicus and cannot be used as valid.