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Background The Antarctic krill, Euphausia superba is a pelagic crustacean, abundant in high-density swarms (10 000 - 30 000 ind/m2) with a circumpolar distribution and a key role in the food web of the Southern Ocean. Only three EST derived microsatellite markers have been used in previous genetic studies, hence we developed additional highly polymorphic microsatellite markers to allow robust studies of the genetic variability and population differentiation within this species. Findings The microsatellite markers described here were obtained through an enriched genomic library, followed by 454 pyrosequencing. A total of 10 microsatellite markers were tested in 32 individuals from the Antarctic Peninsula. One of the tested loci was fixed for one allele while the other was variable. Of the remaining nine markers, seven showed no departure from Hardy-Weinberg equilibrium. The mean number of alleles was 14.9. Conclusions These markers open perspectives for population genetic studies of this species to unravel genetic structure, dispersal and population biology, vital information for future conservation. [ABSTRACT FROM AUTHOR]

Background The relationship between species diversity and components of ecosystem stability has been extensively studied, whilst the influence of the genetic component of biodiversity remains poorly understood. Here we manipulated both genotypic and allelic richness of the seagrass Zostera noltii, in order to explore their respective influences on the resistance of the experimental population to stress. Thus far intra-specific diversity was not taken into account in management plans, and restoration actions showed very low success. Information is therefore needed to understand the factors affecting resistance and resilience of populations. Results Our results show a positive influence of both allelic and genotypic richness on the resistance of meadows to environmental perturbations. They also show that at the low genotypic (i.e. clonal) richness levels used in prior experimental approaches, the effects of genotypic and allelic richness could not be disentangled and allelic richness was a likely hidden treatment explaining at least part of the effects hitherto attributed to genotypic richness. Conclusions Altogether, these results emphasize the need to acknowledge and take into account the interdependency of both genotypic and allelic richness in experimental designs attempting to estimate their importance alone or in combination. A positive influence of allelic richness on resistance to perturbations, and of allelic richness combined with genotypic richness on the recovery (resilience) of the experimental populations is supported by differential mortality results. These results, on the key species structuring of one of the most threatened coastal ecosystem worldwide, seagrass meadows, support the need to better take into account the distinct compartments of clonal and genetic diversity in management strategies, and in possible restoration plans in the future. [ABSTRACT FROM AUTHOR]

Background: One of the classical questions in evolutionary biology is how evolutionary processes are coupled at the gene and species level. With this motivation, we compare the topological properties (mainly the depth scaling, as a characterization of balance) of a large set of protein phylogenies with those of a set of species phylogenies. Results: The comparative analysis between protein and species phylogenies shows that both sets of phylogenies share a remarkably similar scaling behavior, suggesting the universality of branching rules and of the evolutionary processes that drive biological diversification from gene to species level. In order to explain such generality, we propose a simple model which allows us to estimate the proportion of evolvability/robustness needed to approximate the scaling behavior observed in the phylogenies, highlighting the relevance of the robustness of a biological system (species or protein) in the scaling properties of the phylogenetic trees. Conclusions: The invariance of the scaling properties at levels spanning from genes to species suggests that rules that govern the incapability of a biological system to diversify are equally relevant both at the gene and at the species level. [ABSTRACT FROM AUTHOR]