Genetic diversity and structure of the noble crayfish populations in the Balkan Peninsula revealed by mitochondrial and microsatellite DNA markers

Abstract

Background The noble crayfish (Astacus astacus) is a native European species in decline, with a contracting range and diminishing populations and abundance. Previous studies revealed this species significant genetic diversity in the south-eastern Europe, with populations from the western and the southern part of the Balkan Peninsula being the most divergent. However, sampling of populations from the western part of the Balkans was limited and insufficient for investigating genetic diversity and population divergence for the purpose of conservation planning and management. Thus, the major aim of this study was to fill in this knowledge gap by studying mitochondrial and microsatellite DNA diversity, using 413 noble crayfish from 18 populations from waterbodies in the western part of the Balkan Peninsula. Methods Phylogenetic analysis of studied populations and their mitochondrial diversity were studied using COI and 16S sequences and population genetic structure was described using 15 microsatellite loci. Results Phylogeographic analysis revealed new divergent mitochondrial haplotypes for the populations in the westernmost part of the Balkan Peninsula in the tributaries of the Sava and Drava rivers. Microsatellite data indicated that these populations harbour an important component of genetic diversity within A. astacus. The results suggest that the western part of the Balkans played an important role as microrefugia during the Pleistocene climate fluctuations, allowing the long term persistence of A. astacus populations in this region. These results will also be important to supporting conservation decision making and planning.

Integrating population genetics and species distribution modelling to guide conservation of the noble crayfish, Astacus astacus, in Croatia

“…Precisely, the MJ network showed weak phylogeographic structure and high haplotype-sharing even between geographically distant populations. This finding is consistent with the results of previous studies 9 , 11 showing that the contemporary distribution and genetic structure of A. astacus were shaped through past geo-climatic events, strong anthropogenic influence on its habitat and frequent human mediated translocations that partly eroded their genetic structure. Similarities between distant A. astacus populations in several cases were explained by artificial stockings from different countries or populations 10 , 11 .…”

“…The phylogenetic network based on mtDNA displayed intraspecific relationships within A. astacus consistent with the findings of previous studies 7 – 9 . Our results confirmed the existence of several genetic lineages, with the indication of novel divergent lineage containing haplotypes from Croatia and Slovenia (Hap51/Lsh18 and Hap61/Lsh19).…”

“…The final data set for the microsatellite analyses comprised 413 samples and 15 microsatellite loci; 269 successfully genotyped noble crayfish samples from 12 populations in this study, and reference data from five populations obtained in Gross et al 9 . No evidence of linkage disequilibrium between pairs of loci tested over all populations was detected after Bonferroni correction (p = 0.0004), hence all microsatellites were considered as independent markers.…”

“…Such a case was also observed in our study; crayfish from population JAR were used for aquaculture in the geographically distant hatchery Otočac, and consequently samples from both populations belonged to the same mtDNA lineage and shared the same haplotype (Lsh2). The genetic lineages of A. astacus diversified during the late Pliocene and throughout the Pleistocene, within the period between 1.7 and 0.5 mya 9 . Current A. astacus lineage distribution shows a divergence pattern congruent with the phenomena of insularity and isolation of multiple southern glacial refugia during repeated climatic pulses in the Pleistocene that produced a mosaic of lineages 43 .…”

“…It is naturally distributed in the waterbodies of the Black Sea drainage, with a few recorded populations in the Adriatic Sea drainage that are of anthropogenic origin 6 . Large-scale genetic analyses revealed that A. astacus encompasses several mitochondrial lineages that have separated and diversified during the Pleistocene glaciations in the western and southern Balkans 7 – 9 , as well as in the lower Danube basin 7 . Results of microsatellite analysis revealed a differentiation of northern European populations from central European populations, with the former exhibiting a lower genetic diversity 10 .…”