Evolution of Polyploidy and Functional Diploidization in Sturgeons: Microsatellite Analysis in 10 Sturgeon Species.

Sturgeons (family Acipenseridae) are one of the most endangered groups of animals. Two hundred million years of evolution and multiple ploidy levels make this group a unique subject for studying the evolution of polyploidy in animals. As most sturgeon species have gone through significant functional diploidization, 2 scales of ploidy levels can be distinguished: the "evolutionary scale," which indicates the maximum ploidy level achieved and the "recent scale," which indicates the current functional ploidy level. This study analyzes published and new microsatellites to check the ploidy level and to determine the degrees of functional diploidization in 10 sturgeon species from Europe and Asia. We screened 50 primer pairs newly developed for Acipenser gueldenstaedtii and 40 primer pairs previously developed in other studies for other sturgeon species. The maximal number of alleles per individual of a given species was assessed at 20 microsatellite loci, which showed consistent amplification in most of the 10 analyzed species. Taken together, our data on the percentage of disomic loci in different species suggest that functional diploidization is an ongoing process in sturgeons. We observed lower levels of diploidization in tetraploid species from the Atlantic clade than in the species from the Pacific clade, which can be explained by the more recent genome duplication in tetraploid species from the Atlantic clade. Based on the recent findings and results of this study, we propose that the evolution of sturgeons has been affected by at least 3 different polyploidization events.

Isolation of 12 microsatellite markers following a pyrosequencing procedure and cross-priming in two invasive cryptic species, Alexandrium catenella (group IV) and A. tamarense (group III) (Dinophyceae).

Alexandrium catenella (group IV) and Alexandrium tamarense (group III) (Dinophyceae) are two cryptic invasive phytoplankton species belonging to the A. tamarense species complex. Their worldwide spread is favored by the human activities, transportation and climate change. In order to describe their diversity in the Mediterranean Sea and understand their settlements and maintenances in this area, new microsatellite markers were developed based on Thau lagoon (France) samples of A. catenella and A. tamarense strains. In this study twelve new microsatellite markers are proposed. Five of these microsatellite markers show amplifications on A. tamarense and ten on A. catenella. Three of these 12 microsatellite markers allowed amplifications on both cryptic species. Finally, the haplotypic diversity ranged from 0.000 to 0.791 and 0.000 to 0.942 for A. catenella and A. tamarense respectively.

Genetic diversity and conservation of the Prespa trout in the Balkans.

The Balkans are known to have a high level of biodiversity and endemism. No less than 15 taxa have been recorded in salmonids of the Salmo genus. Among them, the Prespa trout is found in only four river systems flowing into Lake Macro Prespa, three in the Former Yugoslav Republic of Macedonia and one in Greece. This is the first comprehensive survey of all streams located within the Macro Prespa Basin, encompassing the whole taxon range. A large genetic sample of 536 Prespa trout was collected mainly between 2005 and 2007. The sampling included 59 individuals from the Golema river system, 93 from the Kranska, 260 from the Brajcinska, 119 from the Agios Germanos, and five individuals from the lake itself. These specimens were analyzed with six microsatellite markers and by sequencing the mitochondrial control region. Nuclear data were examined through multidimensional analysis and assignment tests. Five clusters were detected by assignment: Golema, Kranska, Brajcinska upstream, Rzanska Brajcinska tributary and Brajcinska downstream. Most of these river systems thus hosted differentiated Prespa trout populations (with past gene flows likely dating before the construction of dams), except Agios Germanos, which was found to be composed of 5% to 32% of each cluster. Among the five trout individuals from the lake, four originated from Kranska River and one was admixed. Supported parsimonious hypotheses are proposed to explain these specificities. Conservation of this endemic taxon should take these results into account. No translocation should be performed between different tributaries of the lake and preservation of the Brajcinska populations should address the upstream-downstream differentiation described.