Browsing by Subject "Genetic diversity"

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  • DiLeo, Michelle F.; Rico, Yessica; Boehmer, Hans Juergen; Wagner, Helene H. (2017)
    Ecological connectivity networks have been proposed as an efficient way to reconnect communities in fragmented landscapes. Yet few studies have evaluated if they are successful at enhancing actual functional connectivity (i.e. realized dispersal or gene flow) of focal species, or if this enhanced connectivity is enough to maintain genetic diversity and fitness of plant populations. Here we test the efficacy of an ecological connectivity network implemented in southern Germany since 1989 to reconnect calcareous grassland fragments through rotational shepherding. We genotyped 1449 individuals from 57 populations and measured fitness-related traits in 10 populations of Puisatilla vulgaris, a flagship species of calcareous grasslands in Europe. We tested if the shepherding network explained functional connectivity in P. vulgaris and if higher connectivity translated to higher genetic diversity and fitness of populations. We found that population-specific F-st was lowest in populations that had high connectivity within the shepherding network, and that well-connected populations within the network had significantly higher genetic diversity than ungrazed and more isolated grazed populations. Moreover, genetic diversity was significantly positively correlated with both seed set and seed mass. Together our results suggest that the implementation of an ecological shepherding network is an effective management measure to maintain functional connectivity and genetic diversity at the landscape scale for a calcareous grassland specialist. Populations with reduced genetic diversity would likely benefit from inclusion, or better integration into the ecological connectivity network. Our study demonstrates the often postulated but rarely tested sequence of positive associations between connectivity, genetic diversity, and fitness at the landscape scale, and provides a framework for testing the efficacy of ecological connectivity networks for focal species using molecular genetic tools.
  • Smaragdov, M. G.; Kudinov, A. A. (2020)
    Background Due to the advent of SNP array technology, a genome-wide analysis of genetic differences between populations and breeds has become possible at a previously unattainable level. The Wright's fixation index (F-st) and the principal component analysis (PCA) are widely used methods in animal genetics studies. In paper we compared the power of these methods, their complementing each other and which of them is the most powerful. Results Comparative analysis of the power Principal Components Analysis (PCA) and F-st were carried out to reveal genetic differences between herds of Holsteinized cows. Totally, 803 BovineSNP50 genotypes of cows from 13 herds were used in current study. Obtained F-st values were in the range of 0.002-0.012 (mean 0.0049) while for rare SNPs with MAF 0.0001-0.005 they were even smaller in the range of 0.001-0.01 (mean 0.0027). Genetic relatedness of the cows in the herds was the cause of such small F-st values. The contribution of rare alleles with MAF 0.0001-0.01 to the F-st values was much less than common alleles and this effect depends on linkage disequilibrium (LD). Despite of substantial change in the MAF spectrum and the number of SNPs we observed small effect size of LD - based pruning on F-st data. PCA analysis confirmed the mutual admixture and small genetic difference between herds. Moreover, PCA analysis of the herds based on the visualization the results of a single eigenvector cannot be used to significantly differentiate herds. Only summed eigenvectors should be used to realize full power of PCA to differentiate small between herds genetic difference. Finally, we presented evidences that the significance of F-st data far exceeds the significance of PCA data when these methods are used to reveal genetic differences between herds. Conclusions LD - based pruning had a small effect on findings of F-st and PCA analyzes. Therefore, for weakly structured populations the LD - based pruning is not effective. In addition, our results show that the significance of genetic differences between herds obtained by F-st analysis exceeds the values of PCA. Proposed, to differentiate herds or low structured populations we recommend primarily using the F-st approach and only then PCA.
  • Smaragdov, M. G; Kudinov, A. A (BioMed Central, 2020)
    Abstract Background Due to the advent of SNP array technology, a genome-wide analysis of genetic differences between populations and breeds has become possible at a previously unattainable level. The Wright’s fixation index (Fst) and the principal component analysis (PCA) are widely used methods in animal genetics studies. In paper we compared the power of these methods, their complementing each other and which of them is the most powerful. Results Comparative analysis of the power Principal Components Analysis (PCA) and Fst were carried out to reveal genetic differences between herds of Holsteinized cows. Totally, 803 BovineSNP50 genotypes of cows from 13 herds were used in current study. Obtained Fst values were in the range of 0.002–0.012 (mean 0.0049) while for rare SNPs with MAF 0.0001–0.005 they were even smaller in the range of 0.001–0.01 (mean 0.0027). Genetic relatedness of the cows in the herds was the cause of such small Fst values. The contribution of rare alleles with MAF 0.0001–0.01 to the Fst values was much less than common alleles and this effect depends on linkage disequilibrium (LD). Despite of substantial change in the MAF spectrum and the number of SNPs we observed small effect size of LD - based pruning on Fst data. PCA analysis confirmed the mutual admixture and small genetic difference between herds. Moreover, PCA analysis of the herds based on the visualization the results of a single eigenvector cannot be used to significantly differentiate herds. Only summed eigenvectors should be used to realize full power of PCA to differentiate small between herds genetic difference. Finally, we presented evidences that the significance of Fst data far exceeds the significance of PCA data when these methods are used to reveal genetic differences between herds. Conclusions LD - based pruning had a small effect on findings of Fst and PCA analyzes. Therefore, for weakly structured populations the LD - based pruning is not effective. In addition, our results show that the significance of genetic differences between herds obtained by Fst analysis exceeds the values of PCA. Proposed, to differentiate herds or low structured populations we recommend primarily using the Fst approach and only then PCA.
  • Tanhuanpää, Pirjo; Erkkilä, Maria; Kalendar, Ruslan; Schulman, Alan Howard; Manninen, Outi (2016)
    Timothy (Phleum pratense L.), a cool-season hexaploid perennial, is the most important forage grass species in Nordic countries. Earlier analyses of genetic diversity in a collection of 96 genebank accessions of timothy with SSR markers demonstrated high levels of diversity but could not resolve population structure. Therefore, we examined a subset of 51 accessions with REMAP markers, which are based on retrotransposons, and compared the diversity results with those obtained with SSR markers.
  • Khapilina, Oxana; Raiser, Olesya; Danilova, Alevtina; Shevtsov, Vladislav; Turzhanova, Ainur; Kalendar, Ruslan (2021)
    Analysis of the genetic diversity of natural populations of threatened and endangered species of plants is a main aspect of conservation strategy. The endangered species Allium altaicum is a relict plant of the Ice Age and natural populations are located in extreme climatic conditions of Kazakstan's Altai Mountains. Mobile genetic elements and other interspersed repeats are basic components of a eukaryote genome, which can activate under stress conditions and indirectly promote the survival of an organism against environmental stresses. Detections of chromosomal changes related to recombination processes of mobile genetic elements are performed by various PCR methods. These methods are based on interspersed repeat sequences and are an effective tool for research of biological diversity of plants and their variability. In our research, we used conservative sequences of tRNA primer binding sites (PBS) when initializing the retrotransposon replication as PCR primers to research the genetic diversity of 12 natural populations of A. altaicum found in various ecogeographic conditions of the Kazakhstani Altai. High efficiency of the PBS amplification method used was observed already at the intrapopulation level. Unique amplicons representative of a certain population were found at the intrapopulation level. Analysis of molecular dispersion revealed that the biodiversity of populations of mountainous and lowland A. altaicum is due to intrapopulation differences for climatic zones of habitation. This is likely conditional upon predominance of vegetative reproduction over seed reproduction in some populations. In the case of vegetative reproduction, somatic recombination related to the activity of mobile genetic elements are preserved in subsequent generations. This leads to an increase of intrapopulation genetic diversity. Thus, high genetic diversity was observed in populations such as A. altaicum located in the territory of the Kalbinskii Altai, whereas the minimum diversity was observed in the populations of the Leninororsk ecogeographic group. Distinctions between these populations were also identified depending on the areas of their distribution. Low-land and mid-mountain living environments are characterized by a great variety of shapes and plasticity. This work allowed us to obtain new genetic data on the structure of A. altaicum populations on the territory of the Kazakhstan Altai for the subsequent development of preservation and reproduction strategies for this relict species.
  • Milovanov, Alexander; Zvyagin, Andrey; Daniyarov, Asset; Kalendar, Ruslan; Troshin, Leonid (2019)
    Cultivated grapevine (Vitis vinifera L. ssp. sativa D.C.) is one of the oldest agricultural crops, each variety comprising an array of clones obtained by vegetative propagation from a selected vine grown from a single seedling. Most clones within a variety are identical, but some show a different form of accession, giving rise to new divergent phenotypes. Understanding the associations among the genotypes within a variety is crucial to efficient management and effective grapevine improvement. Inter-primer binding-site (iPBS) markers may aid in determining the new clones inside closely related genotypes. Following this idea, iPBS markers were used to assess the genetic variation of 33 grapevine genotypes collected from Russia. We used molecular markers to identify the differences among and within five grapevine clonal populations and analysed the variation, using clustering and statistical approaches. Four of a total of 30 PBS primers were selected, based on amplification efficiency. Polymerase chain reaction (PCR) with PBS primers resulted in a total of 1412 bands ranging from 300 to 6000 bp, with a polymorphism ratio of 44%, ranging from 58 to 75 bands per group. In total, were identified seven private bands in 33 genotypes. Results of molecular variance analysis showed that 40% of the total variation was observed within groups and only 60% between groups. Cluster analysis clearly showed that grapevine genotypes are highly divergent and possess abundant genetic diversities. The iPBS PCR-based genome fingerprinting technology used in this study effectively differentiated genotypes into five grapevine groups and indicated that iPBS markers are useful tools for clonal selection. The number of differences between clones was sufficient to identify them as separate clones of studied varieties containing unique mutations. Our previous phenotypic and phenological studies have confirmed that these genotypes differ from those of maternal plants. This work emphasized the need for a better understanding of the genotypic differences among closely related varieties of grapevine and has implications for the management of its selection processes.
  • Turzhanova, Ainur; Khapilina, Oxana; Tumenbayeva, A; Shevtsov, Vladislav; Raiser, Olesya; Kalendar, Ruslan (2020)
    The genus Alternaria is a widely distributed major plant pathogen that can act as a saprophyte in plant debris. Fungi of this genus frequently infect cereal crops and cause such diseases as black point and wheat leaf blight, which decrease the yield and quality of cereal products. A total of 25 Alternaria sp. isolates were collected from germ grains of various wheat cultivars from different geographic regions in Kazakhstan. We investigated the genetic relationships of the main Alternaria species related to black point disease of wheat in Kazakhstan, using the inter-primer binding site (iPBS) DNA profiling technique. We used 25 retrotransposon-based iPBS primers to identify the differences among and within Alternaria species populations, and analyzed the variation using clustering (UPGMA) and statistical approaches (AMOVA). Isolates of Alternaria species clustered into two main genetic groups, with species of A.alternata and A.tennuissima forming one cluster, and isolates of A. infectoria forming another. The genetic diversity found using retrotransposon profiles was strongly correlated with geographic data. Overall, the iPBS fingerprinting technique is highly informative and useful for the evaluation of genetic diversity and relationships of Alternaria species.
  • Ruuskanen, Jutta (Helsingin yliopisto, 2020)
    Arapaima gigas is one of the world’s largest freshwater fishes and it is native to the Amazon region. The species is over-exploited and sustainable long-term conservation strategies are needed to maintain the genetic diversity of the species. The aim of this study was to analyze the genetic diversity of Peruvian Arapaima gigas populations. The microsatellite data was collected as a part of a three-year project by the Regional Government of San Martín (GORESAM) and Finnish Game and Fisheries Research Institute (FGFRI). The data consisted of 15 microsatellite loci and 324 samples from three populations, Iquitos, Paiche, and Pucallpa. The samples for Iquitos and Pucallpa were collected from populations in the Amazon basin. Samples of Paiche were collected from a captive population in a fish farming research center. The average numbers of alleles and genotypes ranged between 1.9-3.3 and 2.5-4.6, respectively. Population Pucallpa showed the highest average level of heterozygosity (0.41), whereas the lowest level was observed in population Iquitos (0.25). There were altogether 13 loci which showed a statistically significant excess of heterozygosity, and nine loci with significant deficiency of heterozygosity across the three populations. The FIS-values were in accordance with most of the significant deviations indicating the excess or deficiency of heterozygosity. The average FIT-value (0.226) indicated a slight increase of homozygotes. Populations Iquitos and Paiche were on a state of Hardy-Weinberg equilibrium, but population Pucallpa showed a statistically significant deviation from the state of equilibrium. The pairwise FST-values ranged between 0.169-0.373, and they indicate that the three studied populations are genetically different. In addition, the values of Nei’s genetic distance (D) and full-pedigree likelihood analysis indicate a genetic differentiation between the populations. The number of migrants (Nm) between the three populations was estimated based on the mean frequency of private alleles (p(1) = 0.085) and the mean sample size (108 individuals). The number of migrants was 0.273 after the correction for sample size. The genetic diversity within and between the Peruvian populations resembles the results obtained in other studies of Arapaima gigas in the Amazon basin. Sustainable fish farming could offer a solution in maintaining the genetic diversity of the species.
  • Poczai, Peter; Matyas, Kinga Klara; Szabo, Istvan; Varga, Ildiko; Hyvönen, Jaakko; Cernak, Istvan; Gorji, Ahmad Mosapour; Decsi, Kincso; Taller, Janos (2011)
  • Qaderi, Ardashir; Omidi, Mansour; Pour-Aboughadareh, Alireza; Poczai, Péter; Shaghaghi, Javad; MehrAfarin, Ali; Nohooji, Majid Ghorbani; Etminan, Alireza (2019)
    In the present investigation, 72 accessions of the Iranian poppy (Papaver bracteatum Lindl.) were analyzed for genetic diversity and population structure using start codon targeted polymorphism (SCoT) and inter simple sequence repeat (ISSR) markers along with four important phytochemical traits to provide baseline knowledge for the Iranian poppy’s breeding and conservation plans. Twelve ISSR and thirteen SCoT primers generated a total of 98 and 186 fragments with a mean of 8.17 and 14.31 fragments per primer, respectively. Polymorphic information content for ISSR and SCoT primers ranged from 0.39 to 0.45 and 0.28 to 0.34, with the resolving power ranging from 21.61 to 3.97 and 13.08 to 28.02, respectively. Neighbour-joining (NJ) based clustering grouped 72 accessions into three main groups based on two markers studied (ISSR and SCoT) and the combined data (ISSR + SCoT), which associated with their eco-geographical regions. Population structure based analysis divided 72 accessions into 3 subpopulations using ISSR markers, when SCoT was used eight subpopulations were observed. However, when the combined data was used only three subpopulations were found, which corresponded to the grouping observed with the NJ method and these results were supported by principal coordinate analyses (PCoA). Phytochemical analysis revealed that plant capsule has higher total amounts of the alkaloids; thebaine, morphine and oripavine than stem tissues. Interestingly, for the geographical parameters, latitude showed a significant and positive correlation with thebaine extracted from both stem and capsules and the regression results confirmed these associations. Taken together, our results indicated that three populations Ploor, Eil-Teymoor and Anjomane due to their high contents of alkaloids like thebaine as well as the Taham population due to its high content of morphine and oripavine have a strong enough potency to be used in the pharmacy industry.
  • Lado, Sara; Elbers, Jean P.; Rogers, Mark F.; Melo-Ferreira, Jose; Yadamsuren, Adiya; Corander, Jukka; Horin, Petr; Burger, Pamela A. (2020)
    Background Immune-response (IR) genes have an important role in the defense against highly variable pathogens, and therefore, diversity in these genomic regions is essential for species' survival and adaptation. Although current genome assemblies from Old World camelids are very useful for investigating genome-wide diversity, demography and population structure, they have inconsistencies and gaps that limit analyses at local genomic scales. Improved and more accurate genome assemblies and annotations are needed to study complex genomic regions like adaptive and innate IR genes. Results In this work, we improved the genome assemblies of the three Old World camel species - domestic dromedary and Bactrian camel, and the two-humped wild camel - via different computational methods. The newly annotated dromedary genome assembly CamDro3 served as reference to scaffold the NCBI RefSeq genomes of domestic Bactrian and wild camels. These upgraded assemblies were then used to assess nucleotide diversity of IR genes within and between species, and to compare the diversity found in immune genes and the rest of the genes in the genome. We detected differences in the nucleotide diversity among the three Old World camelid species and between IR gene groups, i.e., innate versus adaptive. Among the three species, domestic Bactrian camels showed the highest mean nucleotide diversity. Among the functionally different IR gene groups, the highest mean nucleotide diversity was observed in the major histocompatibility complex. Conclusions The new camel genome assemblies were greatly improved in terms of contiguity and increased size with fewer scaffolds, which is of general value for the scientific community. This allowed us to perform in-depth studies on genetic diversity in immunity-related regions of the genome. Our results suggest that differences of diversity across classes of genes appear compatible with a combined role of population history and differential exposures to pathogens, and consequent different selective pressures.
  • Lado, Sara; Elbers, Jean P; Rogers, Mark F; Melo-Ferreira, José; Yadamsuren, Adiya; Corander, Jukka; Horin, Petr; Burger, Pamela A (BioMed Central, 2020)
    Abstract Background Immune-response (IR) genes have an important role in the defense against highly variable pathogens, and therefore, diversity in these genomic regions is essential for species’ survival and adaptation. Although current genome assemblies from Old World camelids are very useful for investigating genome-wide diversity, demography and population structure, they have inconsistencies and gaps that limit analyses at local genomic scales. Improved and more accurate genome assemblies and annotations are needed to study complex genomic regions like adaptive and innate IR genes. Results In this work, we improved the genome assemblies of the three Old World camel species – domestic dromedary and Bactrian camel, and the two-humped wild camel – via different computational methods. The newly annotated dromedary genome assembly CamDro3 served as reference to scaffold the NCBI RefSeq genomes of domestic Bactrian and wild camels. These upgraded assemblies were then used to assess nucleotide diversity of IR genes within and between species, and to compare the diversity found in immune genes and the rest of the genes in the genome. We detected differences in the nucleotide diversity among the three Old World camelid species and between IR gene groups, i.e., innate versus adaptive. Among the three species, domestic Bactrian camels showed the highest mean nucleotide diversity. Among the functionally different IR gene groups, the highest mean nucleotide diversity was observed in the major histocompatibility complex. Conclusions The new camel genome assemblies were greatly improved in terms of contiguity and increased size with fewer scaffolds, which is of general value for the scientific community. This allowed us to perform in-depth studies on genetic diversity in immunity-related regions of the genome. Our results suggest that differences of diversity across classes of genes appear compatible with a combined role of population history and differential exposures to pathogens, and consequent different selective pressures.
  • Seppä, Perttu; Bonelli, Mariaelena; Dupont, Simon; Hakala, Sanja Maria; Bagnères, Anne-Geneviève; Lorenzi, M. Cristina (2020)
    Simple Summary The co-evolution of hosts and parasites depends on their ability to adapt to each other's defense and counter-defense mechanisms. The strength of selection on those mechanisms may vary among populations, resulting in a geographical mosaic of co-evolution. The boreo-montane paper wasp Polistes biglumis and its parasite Polistes atrimandibularis exemplify this type of co-evolutionary system. Here, we used genetic markers to examine the genetic population structures of these wasps in the western Alps. We found that both host and parasite populations displayed similar levels of genetic variation. In the host species, populations located near to each other were genetically similar; in both the host and the parasite species populations farther apart were significantly different. Thus, apparent dispersal barriers (i.e., high mountains) did not seem to restrict gene flow across populations as expected. Furthermore, there were no major differences in gene flow between the two species, perhaps because P. atrimandibularis parasitizes both alpine and lowland host species and annually migrates between alpine and lowland populations. The presence of strong gene flow in a system where local populations experience variable levels of selection pressure challenges the classical hypothesis that restricted gene flow is required for local adaptations to evolve. The co-evolutionary pathways followed by hosts and parasites strongly depend on the adaptive potential of antagonists and its underlying genetic architecture. Geographically structured populations of interacting species often experience local differences in the strength of reciprocal selection pressures, which can result in a geographic mosaic of co-evolution. One example of such a system is the boreo-montane social wasp Polistes biglumis and its social parasite Polistes atrimandibularis, which have evolved local defense and counter-defense mechanisms to match their antagonist. In this work, we study spatial genetic structure of P. biglumis and P. atrimandibularis populations at local and regional scales in the Alps, by using nuclear markers (DNA microsatellites, AFLP) and mitochondrial sequences. Both the host and the parasite populations harbored similar amounts of genetic variation. Host populations were not genetically structured at the local scale, but geographic regions were significantly differentiated from each other in both the host and the parasite in all markers. The net dispersal inferred from genetic differentiation was similar in the host and the parasite, which may be due to the annual migration pattern of the parasites between alpine and lowland populations. Thus, the apparent dispersal barriers (i.e., high mountains) do not restrict gene flow as expected and there are no important gene flow differences between the species, which contradict the hypothesis that restricted gene flow is required for local adaptations to evolve.
  • Sinai, Iftah; Segev, Ori; Wei, Gilad; Oron, Talya; Merilä, Juha; Templeton, Alan R.; Blaustein, Leon; Greenbaum, Gili; Blank, Lior (2019)
    Genetic studies on core versus peripheral populations have yielded many patterns. This diversity in genetic patterns may reflect diversity in the meaning of peripheral populations as defined by geography, gene flow patterns, historical effects, and ecological conditions. Populations at the lower latitude periphery of a species' range are of particular concern because they may be at increased risk for extinction due to global climate change. In this work we aim to understand the impact of landscape and ecological factors on different geographical types of peripheral populations with respect to levels of genetic diversity and patterns of local population differentiation. We examined three geographical types of peripheral populations of the endangered salamander, Salamandra infraimmaculata, in Northern Israel, in the southernmost periphery of the genus Salamandra, by analyzing the variability in 15 microsatellite loci from 32 sites. Our results showed that: (1) genetic diversity decreases towards the geographical periphery of the species' range; (2) genetic diversity in geographically disjunct peripheral areas is low compared to the core or peripheral populations that are contiguous to the core and most likely affected by a founder effect; (3) ecologically marginal conditions enhance population subdivision. The patterns we found lead to the conclusion that genetic diversity is influenced by a combination of geographical, historical, and ecological factors. These complex patterns should be addressed when prioritizing areas for conservation.