During laboratory and field experiments on Nacella concinna on the west coast of Admiralty Bay, King George Island (Antarctica) clear morphological and behavioural differences between two limpet forms (N. concinna polaris and N. concinna concinna) were found. They suggested presence of genetic divergence. AFLP (amplified fragment length polymorphism) profiling of N. concinna individuals representing the two forms revealed nearly 32% of polymorphic bands; only 2% of them differed between the forms. Our results suggest that the observed phenotypic variation seems to be a result of adaptation to environ− mental conditions and not of any genetic divergence.
Antarctic pearlwort ( Colobanthus quitensis ) is one of the flowering plant species considered native to maritime Antarctica. Although the species was intensively analyzed towards its morphological, anatomical and physiological adaptation to local environment, its genetic variability is still poorly studied. In the presented study, a recently developed retrotransposon−based DNA marker system (inter Primer Binding Site – iPBS) was applied to assess the genetic diversity and differentiation of C. quitensis populations from King George Island (South Shetland Islands, West Antarctic). A total of 143 scoreable bands were detected using 7 iPBS primers among 122 plant specimens representing 8 populations. 55 (38.5%) bands were found polymorphic, with an average of 14.3% polymorphic fragments per primer. Nine of all observed fragments were represented as a private bands deployed unevenly among populations. Low genetic diversity (on average H e = 0.040 and I = 0.061) and moderate population differentiation (F ST = 0.164) characterize the analyzed material. Clustering based on PCoA revealed, that the populations located on the edges of the study area diverge from the central populations. The pattern of population differentiation corresponds well with their geographic location and the characteristics of the sampling sites. Due to the character of iPBS markers, the observed genetic variability of populations may be explained by the genome rearrangements caused by mobilization of mobile genetic elements in the response to various stress factors. Additionally, this study demonstrates the usefulness of iPBS markers for genetic diversity studies in wild species.
The eurybathic isopod species Chelator insignis shows a wide distribution south of Iceland. We analysed 51 specimens from shelf (213–305 m depth), slope (885–891 m and 1380–1390 m depth) and deep−sea habitats (2750 m) south of Iceland with different DNA markers. A fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) was studied for 47 specimens, 16S was studied for 36 specimens, and a fragment for the 18S rRNA gene could be amplified for 11 specimens. For the COI data, specimens clustered into five distinct lineages each separated by ³ 20% uncorrected pairwise distances. Both the mitochondrial 16S and the nuclear 18S sequence data further support this deep divergence, suggesting the presence of overlooked species inside the nominal C. insignis . Populations on the shelf occurring east and west of the Reykjanes Ridge were genetically identical suggesting that this ridge is not a barrier to gene flow. However, populations from different depth ranges differed substantially. Our multi−gene analysis suggests that the newly found species likely have more narrow vertical distribution ranges and highlights a possible role of bathymetry in speciation processes.
Potato leaf blight disease caused by Ulocladium atrum (Syn. Stemphylium atrum) is an important and epidemic disease in potato-growing regions of Iran. In this study, 30 isolates of the disease were collected from the main potato-growing regions of Iran and were analyzed on the basis of morphological characterization and pathogenicity. Based on morphological characteristics, all isolates were identified as U. atrum. Pathogenicity studies indicated that all 30 isolates were pathogenic on potato “Agria” to varying degrees. Five U. atrum isolates causing potato leaf blight disease, obtained from the Plant Pathology Laboratory, Isfahan Research Center for Agriculture and Natural Resources, Isfahan, Iran, were also examined in this study. A total of 35 isolates were genetically analyzed using random amplified polymorphic DNA (RAPD) and inter-simple sequence repeats (ISSR) markers. Cluster analysis using the un-weighted pair group method with the arithmetic average (UPGMA) method for RAPD marker revealed no clear grouping of the isolates obtained from different geographical regions. The groupings, based on morphological characteristics, virulence variability and RAPD analysis, were not correlated. Cluster analysis using Jaccard’s coefficient for ISSR divided the U. atrum isolates into four main groups, in which there was no significant correlation between the isolate groupings regarding their geographic location and pathogenicity. Using molecular techniques genetic variability was detected among the accessions, with cophenetic correlation coefficients (CCC) of 0.80 for RAPDs and 0.89 for ISSRs. The RAPD and ISSR marker results corresponded well, with a correlation of 0.55.
Populations of Antarctic hairgrass Deschampsia antarctica Desv. from King George Island exhibit variation in many traits. The reason for that is not evident and could be addressed to variable environmental conditions. Obviously, phenotypic variation could be due to stable or temporal changes in expression pattern as the result of adaptation. Stable changes could be due to mutations or site DNA methylation variation that modified expression pattern. Recently, metAFLP approach was proposed to study such effects. A variant of methylation sensitive AFLP (Amplified Fragment Length Polymorphism), based on the isoschizomeric combinations Acc65 I/ Mse I and Kpn I/ Mse I was applied to analyze the sequence and site DNA methylation differences between two D. antarctica populations exhibiting morphological dissimilarities. Both DNA sequence mutations and site methylation pattern alternations were detected among and within analyzed populations. It is assumed that such changes might have originated as the response to environmental conditions that induced site methylation alternations leading to phenotypic variation of D. antarctica populations from South Shetland Islands.
Aeromonas hydrophila is a valuable indicator of the quality of water polluted by sewage and pathogens that pose a risk for humans and cold-blooded animals, including fi sh. The main aim of this research was to evaluate anthropogenic pollution of river water based on genetic diversity of 82 A. hydrophila strains by means of RAPD, semi-random AP-PCR (ISJ) and the rep-BOX conservative repeats test. Genetic diversity of A. hydrophila was HT = 0.28 (SD = 0.02) for all DNA markers (RAPD, semi random and rep-BOX). None of the analyzed electrophoretic patterns was identical, implying that there were many sources of strain transmission. The presence of genes for aerolysin (aerA), hemolysin (ahh1) and the cytotoxic enzyme complex (AHCYTOGEN) was verifi ed for all tested strains, and drug resistance patterns for tetracycline, enrofl oxacin and erythromycin were determined. The most diverse A. hydrophila strains isolated from river water were susceptible to enrofl oxacine (HS = 0.27), whereas less diverse strains were susceptible to erythromycin (HS = 0.24). The presence of the multidrug resistance marker (ISJ4-25; 1100 bp locus) in the examined strains (resistant to three analyzed drugs) indicates that intensive fi sh cultivation affects the microbiological quality of river water.
This study used ISSR markers to assess the genetic diversity of a collection of 15 genotypes of Salix purpurea and 6 interspecific hybrids, employing 40 of 60 tested ISSR primers generating polymorphic amplification products. The PCR-ISSR method was adapted for S. purpurea by optimizing the annealing temperature for each primer. The polymorphism index of ISSR amplification products was 91.8% for all studied genotypes and 70.4% for S. purpurea genotypes. Nei's genetic identity statistics ranged from 0.538 to 0.958. Nei's genetic distance values were used to build a dendrogram (UPGMA) for the investigated genotypes. The dendrogram shows five clusters, and principal coordinate analysis yielded nearly the same genetic relationships among the studied genotypes. The results confirm the usefulness of ISSR markers for determining genetic diversity in S. purpurea.
The study addresses the challenges facing the law of the sea. Although UNCLOS is rightly described as a constitution of the law of the sea, it does not and cannot give answers to all problems and doubts that arise in practice and that are related to global warming, protection of biodiversity, legal status of genetic resources, controversy concerning shipping, delimitation of areas or the protection of underwater cultural heritage. Hence the question arises, what the ways and means of further development of the law of the sea are. Undoubtedly, one of the possibilities is to develop implementation agreements, of which the third devoted to the protection and sustainable use of marine biodiversity outside national jurisdiction is the subject of an international conference convened by the General Assembly, whose resolutions in the area of the law of the sea play an important role. Undoubtedly, also the importance of the organization of the United Nations system, such as the IMO, FAO, UNESCO, UNEP is significant. There is also the possibility of accepting agreements addressing the issues left by UNCLOS without solution or definition. Not without significance is the soft law and the practice of states as well as the position of the organs appointed by UNCLOS.
Genetic diversity is often considered a major determinant of long term population persistence and its potential to adapt to variable environmental conditions. The ability of populations to maintain their genetic diversity across generations seems to be a major prerequisite for their sustainability, which is particularly important for keystone forest tree species. However, little is known about genetic consequences of demographic alterations occurring during natural processes of ecological succession involving changes in the species composition. Using microsatellites, we investigated genetic diversity of adult and offspring generations in beech (Fagus sylvatica L.) and oak (Quercus robur L.) populations coexisting in a naturally established old-growth forest stand, showing some symptoms of ongoing ecological succession from oak- to beech- dominated forest. In general, adult generations of both species exhibited high levels of genetic diversity (0.657 for beech; 0.821 for oak), which, however, depended on the sets of selected genetic markers. Nevertheless, several symptoms such as differences in genetic diversity indices between generations, significant levels of inbreeding (up to 0.029) and low estimates of effective population size (48-80) confirmed the declining status of the oak population. On the other hand, the uniform distribution of genetic diversity indices across generations, low levels of inbreeding (0.004), low genetic differentiation among adults and offspring and, most importantly, large estimates of effective population size (119-716), all supported beech as a successive and successful tree species in the studied forest stand.