No abstract

Biogeographic barriers for freshwater biota can be effective at various spatial scales. At the largest spatial scale, freshwater organisms can become genetically isolated by their high mountain ranges, vast deserts, and inability to cross oceans. Isolation by distance of aquatic plants is expected to be stronger across than alongside mountain ridges whereas the heterogeneity of habitats among populations and temporary droughts may influence connectivity and hamper dispersal. Suitable aquatic plant habitats became reduced, even for the widespread submerged Potamogeton pectinatus L. (also named Stuckenia pectinata) giving structure to various aquatic habitats. We compared the level of genetic diversity in a heterogeneous series of aquatic habitats across Iran and tested their differentiation over distances and across mountain ranges (Alborz and Zagros) and desert zones (Kavir), with values obtained from temperate region populations. The diversity of aquatic ecosystems across and along large geographic barriers provided a unique ecological situation within Iran. P. pectinatus were considered from thirty-six sites across Iran at direct flight distances ranging from 20 to 1,200 km. Nine microsatellite loci revealed a very high number of alleles over all sites. A PCoA, NJT clustering and STRUCTURE analysis revealed a separate grouping of individuals of southeastern Iranian sites and was confirmed by their different nuclear ITS and cpDNA haplotypes thereby indicating an evolutionary significant unit (ESU). At the level of populations, a positive correlation between allelic differentiation Dest with geographic distance was found. Individual-based STRUCTURE analysis over 36 sites showed 7 genetic clusters. FST and RST values for ten populations reached 0.343 and 0.521, respectively thereby indicating that allele length differences are more important and contain evolutionary information. Overall, higher levels of diversity and a stronger differentiation was revealed among Iranian P. pectinatus than previously observed for temperate European regions, due to regional differences across mountain ranges over long distances.

Potamogetonaceae comprises three closely related genera: Potamogeton, Stuckenia and Groenlandia. The last comprehensive research on this species group in Iran dates back to 1971 (Flora Iranica). In this research we present an identification key to the Potamogetonaceae species in Iran with descriptions of all taxa based on morphological and anatomical studies. 11 species of Potamogeton, three species of Stuckenia and one of Groenlandia are described from Iran. Moreover, a new hybrid (P. pusillus × P. crispus) is described as a new to science. Distribution is outlined for all taxa. The genus Potamogeton and related genera have a wide distribution in different aquatic ecosystems in particular of northern, central and southwestern Iran. The species formerly recorded as P. alpinus was identified as P. schweinfurthii. It is recorded for the flora of Iran for the first time.

Background and aims – Narrow endemics, characterized by small distribution areas and small effective population sizes are prone to extinction due to low genetic variation caused by genetic bottlenecks and drift together with the danger of habitat loss. Astragalus subrecognitus is an endemic species that only occurs in northwestern Iran in mountain steppe at higher elevations above the Qezel Ozan River in the province Zanjan. Methods – In this study, we investigated the genetic structure of the populations of A. subrecognitus using inter simple sequence repeats (ISSR) and sequence-related amplified polymorphism (SRAP) as molecular markers.Key results – We detected two genetic groups, which do however not concur with the geographic origins east and west of the Qezel Ozan River. Extant gene flow between these populations is rather unlikely given their distance of c. 70 km and the lack of suitable habitats for this species in lower areas of the valley in between. Conclusions – From this we conclude that we see an older pattern of geographic isolation that was followed by an exchange of genotypes during a time when migration through the valley was possible. Still, admixture between both genetic clusters was found only in one individual, indicating that broadening of allelic diversity by hybridization between individuals belonging to different genetic clusters might be a slow process. Due to the small size of the population, sparse inhabited area, and also very slow or even lack of regeneration in some places we consider A. subrecognitus according to IUCN Red List criteria as ‘endangered’ species.

-Potamogeton pectinatus L. is a widespread aquatic species distributed widely in aquatic ecosystems of Iran. In this study, inter simple sequence repeat (ISSR) markers were used to assess the genetic diversity of 35 accessions and 175 individuals of P. pectinatus collected from different regions of Iran. In total, 123 polymorphic DNA fragments were amplified from five combinations of ISSR primers. The ISSR based principle coordinate analyses (PCoA) demonstrated four different groups mostly corresponding with their geographic origins (North, Kerman/Fars, Centre and Southwest). The most variable populations were found in the central region of Iran possibly as a consequence of the larger number of samples from that region. The result of molecular variance (AMOVA) attributed 11% of the total genetic variation among and 89% within population variation. The results showed high levels of intra-regional and low inter-regional gene flow between clones, although the Northern accessions were clearly differentiated from the others. There was a low correlation between genetic distance and geographic distance of accessions. The results of STRUCTURE analysis suggested the presence of three genetic groups of this species in Iran, mostly adapted to different ecological conditions. Our results cover one of the gaps of different studies worldwide. In addition, our results confirm high levels of genetic diversity of P. pectinatus in Iran.