Population Assignment Tests Research Articles

Population structure of Guyanagaster necrorhizus supports termite dispersal for this enigmatic fungus.

Understanding how species accomplish dispersal of their propagules can shed light on how they are adapted for their ecosystem. Guyanagaster necrorhizus is a sequestrate fungus, meaning its dispersal propagules, or spores, are entirely enclosed within a fruiting body, termed a sporocarp. This fungus is most closely related to Armillaria and its allies. While Armillaria species form mushrooms and have forcibly discharged spores, G.necrorhizus spores have lost this ability, and by necessity, must be passively dispersed. However, G.necrorhizus does not possess characteristics of other sequestrate fungi with known dispersal mechanisms. Repeated observations of termites feeding on G.necrorhizus sporocarps, and spores subsequently adhering to their exoskeletons, led to the hypothesis that termites disperse G.necrorhizus spores. To test this hypothesis, we used microsatellite markers and population genetics analyses to understand patterns of clonality and population structure of G.necrorhizus. While Armillaria individuals can spread vegetatively over large areas, high genotypic diversity in G.necrorhizus populations suggests spores are the primary mode of dispersal. Spatial genetic structure analyses show that G.necrorhizus sporocarps within 238m of each other are more closely related than would be expected by chance and conservative estimates from population assignment tests suggest gene flow no longer occurs between sporocarps separated by 2km. These distances are consistent with previous studies analysing foraging distances of the termites found associated with G.necrorhizus sporocarps. Termites have rarely been recorded to specifically target fungal sporocarps, making this a potentially novel fungal-insect interaction.

Assessing changes in functional connectivity in a desert bighorn sheep metapopulation after two generations.

Determining how species move across complex and fragmented landscapes and interact with human-made barriers is a major research focus in conservation. Studies estimating functional connectivity from movement, dispersal or gene flow usually rely on a single study period and rarely consider variation over time. We contrasted genetic structure and gene flow across barriers for a metapopulation of desert bighorn sheep (Ovis canadensis nelsoni) using genotypes collected 2000-2003 and 2013-2015. Based on the recently observed but unexpected spread of a respiratory pathogen across an interstate highway previously identified as a barrier to gene flow, we hypothesized that bighorn sheep changed how they interacted with that barrier, and that shifts in metapopulation structure influenced gene flow, genetic diversity and connectivity. Population assignment tests, genetic structure and genetic recapture demonstrated that bighorn sheep crossed the interstate highway in at least one location in 2013-2015, sharply reducing genetic structure between two populations, but supported conclusions of an earlier study that such crossings were very infrequent or unknown in 2000-2003. A recently expanded population established new links and caused decreases in genetic structure among multiple populations. Genetic diversity showed only slight increases in populations linked by new connections. Genetic structure and assignments revealed other previously undetected changes in movements and distribution, but much was consistent. Thus, we observed changes in both structural and functional connectivity over just two generations, but only in specific locations. Movement patterns of species should be revisited periodically to enable informed management, particularly in dynamic and fragmented systems.

Species delimitation in the genus Tamarix: Morphological and molecular data<br />

Tamarix (Tamaricaceae) is an ancient genus in Asia that contains about 54 to 90 species with unresolved taxonomy. Tamarix has major center of speciation in the Pakistan-Afghanistan-Iran-Turkmenistan-S-Kazakhstan-W-China area and in the eastern Mediterranean area. Tamarix species are highly plastic and tolerant to adversity being able to occupy different habitats, thus showing a wide range of ecological variations. Tamarix species have commercial value in the landscape and horticultural trade and are planted for erosion control and as wind breaks. In the genus Tamarix, many species are morphologically very similar probably due, in part, inter-specific hybridization. Tamarix species live in sympatry in Sistan and Baloochestan province of Iran and we have no report on the number of species and their genetic structure. Therefore, we performed morphometric study to delimit the species growing in these two provinces and also used combined ISSR (Inter simple sequence repeat) and RAPD (Random amplified polymorphic DNA) molecular markers to study their genetic structure. Morphological analyses separated plants of 6 studied species in different groups, indicating that morphological characters used can delimit Tamarix species. We also encountered some plants having intermediate morphological characters. AMOVA and Hickory test showed significant genetic differences of the studied species and Mantel test showed significant correlation between genetic distance and geographical distance. STRUCTURE analysis and population assignment test revealed some degree of genetic admixture among the studied species. Assignment tests showed that gene flow mainly occurred among the species that were growing in neighborhood regions. This genetic admixture may be the reason for intermediate morphological characters observed in some the plants.

Genetic and morphological diversity in Tragopogon graminifolius DC. (Asteraceae) in Iran

Tragopogon graminifolius DC. is a medicinal plant species of the genus Tragopogon L. (Asteraceae) that grows in different regions of Iran and is extensively used by locals. There is no report on genetic variability and population structure of this important plant species. Therefore, we studied the genetic diversity, population structure and morphological variability of 14 geographical populations of Tragopogon graminifolius in Iran. AMOVA and Gst analyses revealed significant molecular differences among the studied populations. Mantel test showed significant correlation between genetic distance and geographical distance of the studied populations and indicated that the neighboring populations had a higher degree of gene flow. STRUCTURE plot identified three main gene pools for Tragopogon graminifolius in Iran and population assignment test revealed that gene flow occurred mostly among populations of the same gene flow. The studied populations differed significantly in their morphological and genetic features. These results may be of use for future conservation of this important plant species.

Assessment of genetic diversity of an endangered tooth-carp, Aphanius farsicus (Teleostei: Cyprinodontiformes: Cyprinodontidae) using microsatellite markers.

Genetic structure of an endemic tooth-carp fish, Aphanius farsicus from four different water bodies in the Maharlu Lake basin was investigated by applying five microsatellite markers. All of the five examined microsatellite loci showed polymor-phism pattern. A total of four alleles were detected at five microsatellite loci, with an average of 2.8 to 3.5 alleles per locus. Average values of observed and expected heterozygosity were 0.95±0.09 and 0.64±0.02 respectively. None of the tests of linkage disequilibrium were significant between each pair of loci and no deviation from Hardy-Weinberg equilibrium were detected to test for heterozygote deficiency within populations. The Nei's genetic distance values ranged between 0.03 – 0.13. Analysis of pairwise genetic differentiation between each pair of the populations revealed that fixation index (FST) values ranged from 0.013 to 0.039 and RST ranged from 0.005 to 0.065. High genetic diversity observed within the populations (99%) and low diversity (1%) among them indicating probably high level of gene flow among the studied populations of Fars tooth-carp at the present time or in the past. Regarding low genetic differentiation among the studied populations and results of population assignment test, two hypotheses are suggested and supporting evidence for each hypothesis are provided.

Genotype by sequencing identifies natural selection as a driver of intraspecific divergence in Atlantic populations of the high dispersal marine invertebrate, Macoma petalum.

Mitochondrial DNA analyses indicate that the Bay of Fundy population of the intertidal tellinid bivalve Macoma petalum is genetically divergent from coastal populations in the Gulf of Maine and Nova Scotia. To further examine the evolutionary forces driving this genetic break, we performed double digest genotype by sequencing (GBS) to survey the nuclear genome for evidence of both neutral and selective processes shaping this pattern. The resulting reads were mapped to a partial transcriptome of its sister species, M. balthica, to identify single nucleotide polymorphisms (SNPs) in protein‐coding genes. Population assignment tests, principle components analyses, analysis of molecular variance, and outlier tests all support differentiation between the Bay of Fundy genotype and the genotypes of the Gulf of Maine, Gulf of St. Lawrence, and Nova Scotia. Although both neutral and non‐neutral patterns of genetic subdivision were significant, genetic structure among the regions was nearly 20 times higher for loci putatively under selection, suggesting a strong role for natural selection as a driver of genetic diversity in this species. Genetic differences were the greatest between the Bay of Fundy and all other population samples, and some outlier proteins were involved in immunity‐related processes. Our results suggest that in combination with limited gene flow across the mouth of the Bay of Fundy, local adaptation is an important driver of intraspecific genetic variation in this marine species with high dispersal potential.

Population Genomic Analysis of the Blue CrabCallinectes sapidusUsing Genotyping-By-Sequencing

Previous genetic studies of the blue crab Callinectes sapidus along the U.S. Atlantic and Gulf coasts have reported weak or temporally variable spatial structure, suggesting high gene flow among distant populations possibly facilitated by long-distance larval dispersal or other features of blue crab life history. The use of relatively few genetic markers, however, may have limited power to detect subtle but significant structure that could inform fisheries management. In this study, the potential for genome-scale datasets to uncover subtle patterns of population structure in the blue crab was examined using a high-throughput genotyping approach (genotyping-by-sequencing) that generated data for more than 9,600 single nucleotide polymorphisms (SNPs) in crabs from three populations: Panama City Beach, FL, Agawam River, MA, and Porto Alegre, Brazil. Principle components analyses among the three populations revealed very distinct clustering of the Brazilian samples from U.S. populations, likely reflecting restricted gene flow across the equator. Detailed analysis of population structure between the two U.S. populations revealed low but significant genetic differentiation (FST = 0.0103), with FST values ranging from -0.05 to 0.48. Previous studies have failed to detect significant genetic structure on a similar geographic scale. FST outlier analysis identified 242 loci (2.45% of total) with statistically extreme values at the false discovery rate α = 0.05 level, only 16 of which showed significant sequence homology to annotated proteins via BLASTx alignment. Top BLASTx hits were to crustacean or arthropod sequences and 8 of the 16 had high sequence similarity to transposable elements or related machinery. Finally, results of population assignment tests for the two U.S. populations showed that the full marker dataset provided good power to assign individuals back to their population of origin (∼83% and 92% success for Panama City Beach and Agawam River, respectively), which dropped significantly when using only 500 randomly selected SNPs (∼61% and 72% success). Overall, this study demonstrates the great utility of high-throughput sequencing technologies for characterizing fine-scale patterns of genetic structure in blue crabs, and this approach should substantially improve the delineation of stock structure and further advance our understanding of blue crab population connectivity and ecology.

Genetic diversity of common carp (Cyprinus carpio L.) strains breed in Poland based on microsatellite, AFLP, and mtDNA genotype data

The common carp (Cyprinus carpio L.) has a long-standing history in Polish pond aquaculture, which has given rise to a great number of local breeds, strains and hatchery populations. They are well adapted to their local conditions, play an important role for fisherman's livelihoods and embody valuable genetics for future breeding programs. Proper maintenance of animal genetic resources (AnGR) requires an appropriate strategy based upon the precise knowledge of their genetic structure. This study genetically characterizes 20 common carp strains breed in Poland alongside with wild carp from Onuma Lake in Japan. We study three different types of genetic markers including the 963 AFLP markers, a set of 11 microsatellite loci (STR) and DNA sequences of the mitochondrial control region (D-loop). Bayesian clustering analysis of microsatellite loci divided the studied strains into 17 distinct clusters. Using population assignment test 92.4% of carp individuals were correctly assigned to their strain of origin. Microsatellite and AFLP marker analysis have shown the moderate but significant level of genetic variation between strains (AMOVA 23% and 18.2% respectively). AFLP and STR analysis of genetic distances gave equivalent values and were positively correlated with high values of the Mantel test (r=0.553, n=20, p=0.001). Only two mtDNA haplotypes (H5 and H2) were detected in all studied carp strains with H2 being the most prevalent.This is the first comprehensive genetic research of common carp strains breed in Poland which provided crucial data for the national conservation strategy. This study means that this resource can now be placed within the context of similar studies worldwide allowing the further improvement and breeding work.

Patterns of population genetic structure and diversity across bumble bee communities in the Pacific Northwest

Patterns of genetic structure and diversity are largely mediated by a species’ ecological niche and sensitivity to climate variation. Some species with narrow ecological niches have been found to exhibit increased population differentiation, limited gene flow across populations, and reduced population genetic diversity. In this study, we examine patterns of population genetic structure and diversity of four bumble bee species that are broadly sympatric, but do not necessarily inhabit the same ecological niche in the Pacific Northwest of the United States. Testing for the effect of isolation by geographic distance (IBD) with linearized Fst and Dest found that Bombus sylvicola and B. mixtus exhibited significant IBD across populations. In contrast, both B. melanopygus and B. flavifrons, two species that are distributed across a broad elevation gradient, exhibited no IBD, a result further corroborated by Bayesian a priori population assignment tests. Furthermore, we discovered that B. sylvicola populations distributed on the Olympic Peninsula have significantly less average allelic diversity than populations distributed in the Cascade Mountains. Our results suggest that populations distributed in the Olympic Mountains represent a distinct genetic cluster relative to the Cascade Mountains, with B. sylvicola and B. mixtus likely experiencing the greatest degree of population genetic differentiation relative to B. flavifrons and B. melanopygus. While bumble bees are known to co-exist across a diversity of habitats, our results demonstrate that underlying population genetic structure and diversity may not necessarily be similar across species, and are largely governed by their respective niches.

RAPID-COMMUNICATION Genetic diversity and differentiation in natural populations of Arapaima gigas from lower Amazon revealed by microsatellites.

Genetic variability is one of the important criteria for species conservation decisions. This study aimed to analyze the genetic diversity and the population differentiation of two natural populations of Arapaima gigas, a species with a long history of being commercially exploited. We collected 87 samples of A. gigas from Grande Curuai Lake and Paru Lake, located in the Lower Amazon region of Amazônia, Brazil, and genotyped these samples using a multiplex panel of microsatellite markers. Our results showed that the populations of A. gigas analyzed had high levels of genetic variability, which were similar to those described in previous studies. These two populations had a significant population differentiation supported by the estimates of FST and RST (0.06), by Bayesian analysis (K = 2), and by population assignment tests, which revealed a moderate genetic distance.

Development of the method for identification of selected populations of torpedo scad, Megalaspis cordyla (Linnaeus, 1758), using microsatellite DNA analyses. CELFISH project - Part 4.

Catch and consumption of torpedo scad (Megalaspis cordyla) over the western Indian Ocean, but also the western Pacific from Japan to Australia is constantly increasing. Taking into account the degree of exploitation and missing information on the population structure of torpedo scad stocks it is crucial to provide population data. The analysis included individuals obtained in 2012 and 2013 from local markets in Madagascar, Tanzania, Vietnam and Cambodia and after successful DNA extraction fragment of the nuclear rhodopsin gene (RH1) and 9 microsatellite regions (SSRs) were amplified and analysed. Based on the obtained results it was found that there was no 100% overlap between the compared RH1 sequences and those from GenBank. In the case of the studied SSRs, the results allowed the initial characterisation and assessment of the genetic diversity of populations. Moreover, population assignment test distinguished the studied populations into two geographically distant subpopulations.

From Alaska to Antarctica: Species boundaries and genetic diversity of Prasiola (Trebouxiophyceae), a foliose chlorophyte associated with the bipolar lichen-forming fungus Mastodia tessellata

Symbiotic associations between green algae (Chlorophyta) and fungi give rise to morphologically and eco-physiologically distinct entities, or so-called, lichens. In one of the most peculiar of these associations, the partners are species of the macroscopic genus Prasiola (Trebouxiophyceae) and the ascomycete Mastodia tessellata (Verrucariaceae). This is the only known case of a lichen symbiosis involving a foliose green alga. Despite intense research targeted at understanding the biology of this particular association, little is known about the genetic variability of its symbionts. This study focuses on the photobiont partner of this lichen and was designed to explore and compare its genetic diversity along a latitudinal axis from Alaska to Antarctica. Molecular sequence data were generated for three loci: two nuclear markers (nrITS, RPL10A) and one plastid-encoded marker (tufA). The usefulness of the Prasiola nrITS and RPL10A data was examined at the species and intraspecific levels. We used the population assignment tests implemented in BAPS and STRUCTURE and two algorithmic species delimitation procedures (ABGD, GMYC) to generate species boundary discovery hypotheses, which were subsequently tested using Bayes factors. Population genetic differentiation and structure were also assessed through fixation indices, polymorphism statistics and haplotype networks. Based on the results of the species validation method, we propose that at least two species of Prasiola associate with the lichen-forming fungus Mastodia tessellata. Of these, P. borealis is broadly distributed in Alaska, Tierra del Fuego and the Antarctic Peninsula, whereas the second, undescribed, species is restricted to the Antarctic Peninsula. We detected significant phylogeographic substructure in P. borealis, including greater haplotype diversity in the Tierra del Fuego populations. Our findings provide new data that will be useful to unravel the cryptic diversity and phylogeographic patterns of the green alga partners of lichens.

Discovery of 20,000 RAD–SNPs and development of a 52-SNP array for monitoring river otters

Many North American river otter (Lontra canadensis) populations are threatened or recovering but are difficult to study because they occur at low densities, it is difficult to visually identify individuals, and they inhabit aquatic environments that accelerate degradation of biological samples. Single nucleotide polymorphisms (SNPs) can improve our ability to monitor demographic and genetic parameters of difficult to study species. We used restriction site associated DNA (RAD) sequencing to discover 20,772 SNPs present in Montana, USA, river otter populations, including 14,512 loci that were also variable in at least one other population range-wide. After applying careful filtering criteria meant to minimize ascertainment bias and identify high quality, highly heterozygous (Ho = 0.2–0.50) SNPs, we developed and tested 52 independent SNP qPCR genotyping assays, including 41 that performed well with diluted DNA. The 41 loci provided high power for population assignment tests with only 1 misassignment (1.6 %) between closely neighboring populations. Our SNPs showed high power to differentiate individuals and assign them to population of origin, as well as strong concordance of genotypes from high and diluted concentrations of DNA, and between original RAD and the SNP qPCR array.

Multilocus Phylogeography of the Treefrog Scinax eurydice (Anura, Hylidae) Reveals a Plio-Pleistocene Diversification in the Atlantic Forest.

We aim to evaluate the genetic structure of an Atlantic Forest amphibian species, Scinax eurydice, testing the congruence among patterns identified and proposed by the literature for Pleistocene refugia, microrefugia, and geographic barriers to gene flow such as major rivers. Furthermore, we aim to evaluate predictions of such barriers and refugia on the genetic structure of the species, such as presence/absence of dispersal, timing since separation, and population expansions/contractions. We sequenced mitochondrial and nuclear genetic markers on 94 tissue samples from 41 localities. We inferred a gene tree and estimated genetic distances using mtDNA sequences. We then ran population clustering and assignment methods, AMOVA, and estimated migration rates among populations identified through mtDNA and nDNA analyses. We used a dated species tree, skyline plots, and summary statistics to evaluate concordance between population’s distributions and geographic barriers and Pleistocene refugia. Scinax eurydice showed high mtDNA divergences and four clearly distinct mtDNA lineages. Species tree and population assignment tests supported the existence of two major clades corresponding to northeastern and southeastern Atlantic Forest in Brazil, each one composed of two other clades. Lineage splitting events occurred from late Pliocene to Pleistocene. We identified demographic expansions in two clades, and inexistent to low levels of migrations among different populations. Genetic patterns and demographic data support the existence of two northern Refuge and corroborate microrefugia south of the Doce/Jequitinhonha Rivers biogeographic divide. The results agree with a scenario of recent demographic expansion of lowland taxa. Scinax eurydice comprises a species complex, harboring undescribed taxa consistent with Pleistocene refugia. Two rivers lie at the boundaries among populations and endorse their role as secondary barriers to gene flow.

Contemporary inter-specific hybridization between Cirsium aduncum and C. haussknechtii (Asteraceae): Evidence from molecular and morphological data

Cirsium aduncum Fisch. & C.A.Mey. Ex DC. and C. haussknechtii Boiss., (Asteraceae) are important medicinal plant species that grow in different geographical regions of Iran. We had no knowledge about population genetic structure, intra-specific and inter-specific gene flow and the presence of hybrid zone for this two species in Iran. Therefore, in order to provide data for conservation of these two medicinally important species, the population genetic analysis and morphometric studies were performed in 18 geographical populations of these species. ANOVA and MDS analyses revealed significant morphological difference among the studied populations in either species, while MDS plot showed morphological overlap in plants of these two species. AMOVA test revealed significant genetic difference among the studied populations. Mantel test showed positive significant correlation between genetic and geographical distances and the occurrence of isolation by distance. Population assignment test and STRUCTURE plot of genetic data revealed inter-specific introgression between these species.

SSR and EST-SSR-based population genetic structure of Linum L. (Linaceae) species in Iran

The genus Linum L. (Linaceae) has more than 200 species. These species have agricultural, industrial, and medicinal importance. Domestication and continuous selection reduce genetic diversity of plants and in order to develop new and improved varieties, we should utilize all available genetic diversity in that crop and its wild relatives. The cultivated flax (L. usitatissimum L.) is an important crop plant and is being evaluated as a crop platform for the production of bio-industrial and nutraceutical products. In present study, we studied 230 plants of 23 populations in four Linum species namely, pale flax (L. bienne Mill.), cultivated flax (L. usitatissimum L.), and two wild relatives, L. austriacum L. and L. album L. The objective of this study was to investigate population genetic structure and genetic variability within each species using SSR and EST-SSR markers. The low degree of genetic variability was obtained in these species. AMOVA revealed significant genetic difference among species and populations. The significant correlation was observed between genetic and geographical distances the studied species. Evanno test and K-Means clustering revealed genetic fragmentation in the studied Linum species. Networking and STRUCTURE analysis revealed genetic affinity of the populations. The population assignment test revealed absence of gene flow or the occurrence of very limited gene flow among populations.

Genetic and morphological diversity in Cousinia tabrisiana (Asteraceae) populations

AbstractCousinia Cass. is one of the largest genuses in the Asteraceae. It contains 600 to 700 species in Southwest and Central Asia, in Iran with 270 species is the largest genus after Astragalus, Cousinia probably is unique in the degree of diversification of all its parts and definitely unique in the restricted distribution area of a high number of species. Some of Cousinia species have medicinal value. Perhaps the most important biological challenge today is the conservation of biodiversity. As human population increases, so does the need for natural resources and space for the growing population. In this investigation eighty-seven plant specimens of 8 geographical populations of Cousinia tabrisiana Bunge. were studied from morphological and genetic (ISSR) points of view. Both intra and inter-population morphological and genetic variability was observed in the studied populations. ANOVA and CVA tests revealed significant morphological difference among these populations. Similarly, AMOVA and Hickory tests revealed significant molecular difference among geographical populations. Mantel test produced significant positive correlation between genetic distance and geographical distance of the studied populations. Networking, STRUCTURE analysis and population assignment test revealed some degree of gene flow among these populations. LMFF test identified some of the ISSR loci to be correlated with environmental factors studied and consensus tree of morphological and genetic data identified divergent populations.

Population genetic structure and genetic diversity in <i>Dracocephalum thymiflorum</i> L. (Lamiaceae) populations in Iran

Dracocephalum thymiflorum L. is a medicinal plant that grows in limited areas in Iran and forms few local populations. We have no information on its genetic diversity and population genetic structure in the country. Therefore, the present population genetic study was performed to provide data on population genetic structure, potential gene pools and gene flow in Dracocephalum thymiflorum in Iran. The information obtained can be used in conservation of this medicinal plant species. We studied 55 randomly selected plants from 5 geographical populations by ISSR molecular markers. The studied populations contained high within-population genetic variability and also revealed strong genetic differentiation by AMOVA test (P = 0.01). Structure analysis and K-Means clustering revealed population genetic fragmentation that was mainly due to genetic difference between population 2 and the other studied populations. The population assignment test revealed the occurrence of limited gene flow among these populations. The information obtained can me used in programming the conservation of this important medicinal plant in Iran.

How do you solve a problem like Letharia? A new look at cryptic species in lichen-forming fungi using Bayesian clustering and SNPs from multilocus sequence data.

The inclusion of molecular data is increasingly an integral part of studies assessing species boundaries. Analyses based on predefined groups may obscure patterns of differentiation, and population assignment tests provide an alternative for identifying population structure and barriers to gene flow. In this study, we apply population assignment tests implemented in the programs STRUCTURE and BAPS to single nucleotide polymorphisms from DNA sequence data generated for three previous studies of the lichenized fungal genus Letharia. Previous molecular work employing a gene genealogical approach circumscribed six species-level lineages within the genus, four putative lineages within the nominal taxon L. columbiana (Nutt.) J.W. Thomson and two sorediate lineages. We show that Bayesian clustering implemented in the program STRUCTURE was generally able to recover the same six putative Letharia lineages. Population assignments were largely consistent across a range of scenarios, including: extensive amounts of missing data, the exclusion of SNPs from variable markers, and inferences based on SNPs from as few as three gene regions. While our study provided additional evidence corroborating the six candidate Letharia species, the equivalence of these genetic clusters with species-level lineages is uncertain due, in part, to limited phylogenetic signal. Furthermore, both the BAPS analysis and the ad hoc ΔK statistic from results of the STRUCTURE analysis suggest that population structure can possibly be captured with fewer genetic groups. Our findings also suggest that uneven sampling across taxa may be responsible for the contrasting inferences of population substructure. Our results consistently supported two distinct sorediate groups, ‘L. lupina’ and L. vulpina, and subtle morphological differences support this distinction. Similarly, the putative apotheciate species ‘L. lucida’ was also consistently supported as a distinct genetic cluster. However, additional studies will be required to elucidate the relationships of other L. columbiana s.l. populations with the two sorediate genetic clusters.

Single-nucleotide polymorphism in populations of sockeye salmon Oncorhynchus nerka from Kamchatka Peninsula

The genetic polymorphism of 45 single-nucleotide polymorphism loci was examined in the four largest wild populations of sockeye salmon Oncorhynchusnerka from drainages of the Asian coast of the Pacific Ocean (Eastern and Western Kamchatka). It was demonstrated that sockeye salmon from the Palana River were considerably different from all other populations examined. The most probable explanation of the observed differences is the suggestion on possible demographic events in the history of this population associated with the decrease in its effective number. To study the origin, colonization patterns, and evolution of Asian sockeye salmon, as well as to resolve some of the applied tasks, like population assignment and genetic identification, a differentiation approach to SNP-marker selection was suggested. Adaptively important loci that evolve under the pressure of balancing (stabilizing) selection were identified, thanks to which the number of loci that provide the baseline classification error rates in the population assignment tests was reduced to 30. It was demonstrated that SNPs located in the MHC2 and GPH genes were affected by diversifying selection. Procedures for selecting single-nucleotide polymorphisms for phylogenetic studies of Asian sockeye salmon were suggested. Using principal-component analysis, 17 loci that adequately reproduce genetic differentiation within arid among the regions of the origin of Kamchatka sockeye salmon, were selected.