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BackgroundThe noble crayfish (Astacus astacus) displays a complex historical and contemporary genetic status in Europe. The species divergence has been shaped by geological events (i.e. Pleistocene glaciations) and humanly induced impacts (i.e. translocations, pollution, etc.) on its populations due to species commercial value and its niche degradation. Until now, limited genetic information has been procured for the Balkan area and especially for the southernmost distribution of this species (i.e. Greece). It is well known that the rich habitat diversity of the Balkan Peninsula offers suitable conditions for genetically diversified populations. Thus, the present manuscript revisits the phylogenetic relationships of the noble crayfish in Europe and identifies the genetic make-up and the biogeographical patterns of the species in its southern range limit.ResultsMitochondrial markers (i.e. COI and 16S) were used in order to elucidate the genetic structure and diversity of the noble crayfish in Europe. Two of the six European haplotypic lineages, were found exclusively in Greece. These two lineages exhibited greater haplotypic richness when compared with the rest four (of “Central European” origin) while they showed high genetic diversity. Divergence time analysis identified that the majority of this divergence was captured through Pleistocene, suggesting a southern glacial refugium (Greece, southern Balkans). Furthermore, six microsatellite markers were used in order to define the factors affecting the genetic structure and demographic history of the species in Greece. The population structure analysis revealed six to nine genetic clusters and eight putative genetic barriers. Evidence of bottleneck effects in the last ~5000 years (due to climatic and geological events and human activities) is also afforded. Findings from several other research fields (e.g. life sciences, geology or even archaeology) have been utilized to perceive the genetic make-up of the noble crayfish.ConclusionsThe southernmost part of Balkans has played a major role as a glacial refugium for A. astacus. Such refugia have served as centres of expansion to northern regions. Recent history of the noble crayfish in southern Balkans reveals the influence of environmental (climate, geology and/or topology) and anthropogenic factors.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0971-6) contains supplementary material, which is available to authorized users.

Aim Two species of the brine shrimp, namely Artemia franciscana Kellogg and A. persimilis Piccinelli and Prosdocimi, inhabit Chile. Most studies so far have shown that A. franciscana is the most widely distributed species in Chile, with A. persimilis present only in Chilean Patagonia. In general, there is good agreement between morphological and genetic comparisons of Chilean populations with respect to species discrimination. However, a number of results indicate an overlap with some populations tending to diverge from A. franciscana and/or resembling A. persimilis. Prior to the mid 90's the use of DNA markers in Artemia was rather limited, despite their successful application in numerous other species. In this study, we investigate whether the conclusions drawn from traditional comparative tools are congruent with the pattern of genetic divergence depicted by DNA analysis at the mitochondrial level.Location Eight sites in Chile and two reference samples of A. franciscana and A. persimilis from San Francisco Bay (USA) and Buenos Aires (Argentina), respectively.Methods Restriction fragment length polymorphism (RFLP) analysis of a 535 bp segment of the mitochondrial 16S rRNA gene with nine restriction enzymes in 240 individuals. ResultsNo haplotype was shared between the two species. Five restriction enzymes produced species-specific patterns, enabling the unambiguous assignment of populations to species. Very high (100%) bootstrap values supported the clustering of haplotypes in two groups corresponding to the two species. The two species were clearly differentiated with average sequence divergence of 12.3%. High genetic differentiation was also found among conspecific populations of A. franciscana with an F ST estimate of 91%. Main conclusionsThe mitochondrial DNA (mtDNA) results of this study show a broadly similar pattern to those of previous allozyme and nuclear DNA analyses, with the two New World species appearing as highly divergent. The presence of A. persimilis in southern Chile (Chilean Patagonia) was confirmed. Hence, a species previously regarded as geographically restricted mainly to Argentina, appears to have expanded its range. Populations of A. franciscana appear highly structured with a level of inter-population genetic differentiation much higher for mtDNA than previously reported with allozymes. Clustering of these populations does not follow a clear geographic pattern. The identification of population-specific genetic markers for A. persimilis and A. franciscana will help to tackle further aspects of the speciation patterns of these species.