Microsatellite DNA Loci Research Articles

Поиск новых SSR-локусов ДНК для создания эффективной технологии генотипирования сои

Soybean is the major protein-oil crop of a huge economic importance. Currently, to describe the new cultivars being applied for a patent there are used the modern methods based on an analysis of microsatellite (SSR) loci of DNA. The purposes of this work were a search of the new microsatellite markers to optimize the existing technology of soybean cultivars certification and identification as well as selection of conditions for PCR analysis and to test them on cultivars from the VIR’s collection. Seven microsatellite loci demonstrated the high polymorphism level on soybean cultivars and located in the different chromosomes were chosen in the literary sources and librarian data bases. The optimal temperatures for annealing were selected empirically for all the pairs of SSR-markers. The results of DNA amplification of 20 soybean genotypes showed all seven studied SSR-loci were polyallel. In general, we revealed 22 alleles that on average are 3.1 per a locus. The effective number of alleles Ne for the studied soybean genotypes varied from 1.69 to 2.27 and on average was equal to 2.01. An average meaning of an index of the polymorphic information content (PIC) was 0.50. All the investigated soybean samples have the unique sets of alleles by the studied loci. Seven approbated loci can be used in development of an effective technology for identification and certification of the soybean genotypes.

Formation of the genetic structure of cattle populations by single locus DNA fragments depending on their productivity direction and origin

Aim. Our work was aimed at investigating the specificities in the formation of the genetic structure of populations depending on the productivity direction of cattle, bred in Ukraine, using single locus DNA fragments, and studying the impact of the parental form on genetic polymorphism of modern intensive specialized breeds as a factor. Methods. The following methods were used in the work: veterinary methods (peripheral blood sampling); molecular-genetic meth- ods (the isolation and genotyping of DNA samples of dairy (83 animals), meat (192 animals) and aboriginal (43 ani- mals) cattle, bred in Ukraine, were performed by 10 microsatellite loci from the list, recommended by the International Society for Animal Genetics (ISAG); the complex of statistics methods was used for mathematic-statistical analysis, using modern software. Results. The analysis by 10 microsatellite loci demonstrated the specificities of genetic dif- ferentiation and the similarities between the investigated cattle populations, bred in Ukraine. Our results provide new information about the impact of artificial selection factors on single locus DNA fragments under the specialization of cattle breeds. The impact of the factor of ancestral form on the genetic structure was determined and confirmed by the same polymorphism spectra of the investigated DNA fragments in the maternal and derivative breeds. Another con- firmation was found in the differences, observed in animals of different productivity directions, which are a probable result of the breed-forming process, demonstrated by the results of the mathematic calculations of the data obtained. It was shown that microsatellite DNA loci are highly informative markers of genetic processes, occurring in domestic cattle populations. Conclusions. The specificities in the formation of the genetic structure of populations depending on the productivity direction of animals were determined. The impact of the parental form on genetic polymorphism of modern intensive specialized breeds was noted. It was found that among 10 microsatellite loci, used by us, there were loci in each group of animals, regarding which the hypothesis about their neutrality was reliably rejected accord- ing to the results of Ewens-Watterson test: for dairy cattle (INRA023, ETH3, ETH225, BM1824, BM2113, ETH10 and SPS115), for meat cattle (TGLA122 and ETH225), and for aboriginal cattle (TGLA126, INRA023 and TGLA227). We determined a high level of genetic diversity, remarkable for each investigated cattle population, bred in Ukraine, and general tendencies of differentiation in the selected populations depending on the targeted breeding work, on the level of polymorphism of microsatellite DNA loci (Friedman’s test: P < 0.01), and a similar genetic picture for a number of loci of investigated DNA fragments, which may be related to the history of creating these breeds.

Population connectivity in voles (Microtus sp.) as a gauge for tall grass prairie restoration in midwestern North America.

Ecological restoration can promote biodiversity conservation in anthropogenically fragmented habitats, but effectiveness of these management efforts need to be statistically validated to determine ’success.’ One such approach is to gauge the extent of recolonization as a measure of landscape permeability and, in turn, population connectivity. In this context, we estimated dispersal and population connectivity in prairie vole (Microtus ochrogaster; N = 231) and meadow vole (M. pennsylvanicus; N = 83) within five tall-grass prairie restoration sites embedded within the agricultural matrix of midwestern North America. We predicted that vole dispersal would be constrained by the extent of agricultural land surrounding restored habitat patches, spatially isolating vole populations and resulting in significant genetic structure. We first employed genetic assignment tests based on 15 microsatellite DNA loci to validate field-derived species-designations, then tested reclassified samples with multivariate and Bayesian clustering to assay for spatial and temporal genetic structure. Population connectivity was further evaluated by calculating pairwise FST, then potential demographic effects explored by computing migration rates, effective population size (Ne), and average relatedness (r). Genetic species assignments reclassified 25% of initial field identifications (N = 11 M. ochrogaster; N = 67 M. pennsylvanicus). In M. ochrogaster population connectivity was high across the study area, reflected in little to no spatial or temporal genetic structure. In M. pennsylvanicus genetic structure was detected, but relatedness estimates identified it as kin-clustering instead, underscoring social behavior among populations rather than spatial isolation as the cause. Estimates of Ne and r were stable across years, reflecting high dispersal and demographic resilience. Combined, these metrics suggest the agricultural matrix is highly permeable for voles and does not impede dispersal. High connectivity observed confirms that the restored landscape is productive and permeable for specific management targets such as voles and also demonstrates population genetic assays as a tool to statistically evaluate effectiveness of conservation initiatives.

Genotyping pigs of Ukrainian breeds by microsatellite loci with a tetranucleotide motif

The aim of the research was genotyping animals of Ukrainian pig breeds according to microsatellite loci of the genome for further creation and implementation of the methodology for determining gene complexes of pig adaptability. Research methods: zootechnical – the analysis of genealogy and the productivity indexes of animals of different breeds; bioinformation - work with databases of the primary genome sequences for the design of oligonucleotide primers; molecular genetic - nucleic acid extraction, the determination of purity and concentration of DNA preparations, the amplification of microsatellite loci in PCR with subsequent electrophoretic separation of the amplification products in denaturing gel; statistical – the determination of population-genetic parameters on the basis of typing data on microsatellite loci, the relationship of microsatellite loci with performance indexes, the search for adaptive complexes. It was carried out genotyping animals of the Ukrainian meat breed in SE “RF Elita MIW named after V. M. Remeslo NAAS "of Kyiv region for 6 microsatellite loci with tetranucleotide repeats, a panel of primers of its own design. It was found the fact that the average number of alleles per locus was 5.2 alleles. The level of actual heterozygosity was 0.830, while the expected heterozygosity was 0.780. However, this difference is not significant. DNA typing animals for 6 loci of microsatellite DNA of 17 heads of Poltava meat breed of SE "EB Nadiia" was carried out. As a result of genotyping, the average number of alleles per locus was 3.8. The actual and expected heterozygosity levels were 0.680 and 0.730, respectively. By loci of microsatellite DNA, we found in animals of Myrhorod breed: for locus FH3628 – 5 alleles of 200-228 nucleotides, FH1865 – 5 alleles (size from 109 to 129 nucleotides), FH4219 – 2 alleles of 80 and 92 nucleotides, FH1885 – 4 alleles from 205 up to 213 nucleotides, FH3764 – 2 alleles 138 and 146 nucleotides, and for FH4231 – 2 alleles 116 and 120 nucleotides. The level of actual heterozygosity was 0.860, while the expected heterozygosity was 0.810. Thus, in three breeds of Ukrainian selection for 6 loci of microsatellite DNA with tetranucleotide repeat, the level of actual heterozygosity was in the range of 0.680 in animals of Poltava meat breed to 0.860 in animals of Myrhorod breed. The level of expected heterozygosity is 0.730 in animals of Poltava meat breed to 0.810 in Myrhorod breed. The high level of heterozygosity, as well as the average number of alleles per locus allows to search for alleles and genotypes associated with the adaptability of animals in breeds of pigs of Ukrainian selection. Key words: pigs, microsatellite loci, genome, average number of alleles, level of heterozygosity, population, variability.

Limited Introgression between Rock-Wallabies with Extensive Chromosomal Rearrangements.

Chromosome rearrangements can result in the rapid evolution of hybrid incompatibilities. Robertsonian fusions, particularly those with monobrachial homology, can drive reproductive isolation amongst recently diverged taxa. The recent radiation of rock-wallabies (genus Petrogale) is an important model to explore the role of Robertsonian fusions in speciation. Here, we pursue that goal using an extensive sampling of populations and genomes of Petrogale from north-eastern Australia. In contrast to previous assessments using mitochondrial DNA or nuclear microsatellite loci, genomic data are able to separate the most closely related species and to resolve their divergence histories. Both phylogenetic and population genetic analyses indicate introgression between two species that differ by a single Robertsonian fusion. Based on the available data, there is also evidence for introgression between two species which share complex chromosomal rearrangements. However, the remaining results show no consistent signature of introgression amongst species pairs and where evident, indicate generally low introgression overall. X-linked loci have elevated divergence compared with autosomal loci indicating a potential role for genic evolution to produce reproductive isolation in concert with chromosome change. Our results highlight the value of genome scale data in evaluating the role of Robertsonian fusions and structural variation in divergence, speciation, and patterns of molecular evolution.

Assessing the origin, genetic structure and demographic history of the common pheasant (Phasianus colchicus) in the introduced European range

The common pheasant, a game species widely introduced throughout the world, can be considered as an ideal model to study the effects of introduction events on local adaptations, biogeographic patterns, and genetic divergence processes. We aimed to assess the origin, spatial patterns of genetic variation, and demographic history of the introduced populations in the contact zone of Central and Southeast Europe, using mitochondrial DNA control region sequences and microsatellite loci. Both types of molecular markers indicated relatively low to moderate levels of genetic variation. The mtDNA analyses revealed that common pheasants across the study area are divided into two distinct clades: B (mongolicus group) and F (colchicus group). Analyses of the microsatellite data consistently suggested a differentiation between Hungary and Serbia, with the pheasant population in Hungary being much more genetically homogeneous, while that of Serbia has much more genetic mixture and admixture. This cryptic differentiation was not detected using a non-spatial Bayesian clustering model. The analyses also provided strong evidence for a recent population expansion. This fundamental information is essential for adequate and effective conservation management of populations of a game species of great economic and ecological importance in the studied geographical region.

Influences of Small Hydroelectric Plants on the genetic differentiation of Neotropical freshwater fish populations: a case study

ABSTRACT In view of the growing global demand for electricity, many countries have been looking for ways to diversify production. However, in countries such as Brazil, hydroelectric power plants still constitute the predominant generating source, occupying important drainage systems, such as the Upper Paraná River. At the same time, hydroelectric dams are among the main sources of impacts on freshwater fish, interfering, for example, in the genetic distribution of populations. Although the same could be expected from Small Hydroelectric Plants, very little genetic information has been obtained along Neotropical drainages. Based on this, the present study analyzed the DNA (microsatellite loci) of non-migratory fish species (seven) upstream and downstream of three Small Hydroelectric Plants in the Upper Paraná River basin, obtaining information about the genetic distribution of fish populations in this scenario. In general, the data suggest that populations have been genetically subdivided by Small Hydroelectric Plants and that other factors, such as the number of Small Hydroelectric Plants along a drainage and connectivity with long free stretches, could also influence genetic differentiation levels, which provides information of great relevance to global discussions about the impacts of hydroelectric power plants, as well as for the implementation and management of projects.

Hybridization of Two Species of Japanese Toads, Bufo torrenticola and Bufo japonicus formosus, in the Central Part of Japan.

Interspecific hybridization between two species of Japanese toads, Bufo torrenticola (Bt) and Bufo japonicus formosus (Bjf), was not thought to have occurred due to the differences in their spawning habitats, although their hybridization was reported by previous research in a limited area. Such hybridization could have pivotal effects, such as genetic admixture, on Bt, which has a limited distribution and habitat. In this study, to clarify the details of hybridization, a total of 192 individuals were collected from multiple parapatric regions and an only Bjf allopatric region and analyzed based on morphology, mtDNA sequences, and nuclear DNA microsatellite loci. Each individual was identified based on morphological type and mtDNA lineage, and two mismatched combinations, Bt or an intermediate morphological type and the Bjf mtDNA lineage, were detected. In particular, the combination of Bt type and Bjf lineage was dominant in parapatric regions, and it was considered that asymmetric hybridization in which Bjf became a matriline had occurred. In addition, a Bayesian clustering method based on the microsatellite loci was conducted to detect a genetic admixture of the two toad species. Individuals representing a combination of the Bt type and Bjf lineage in the parapatric regions were largely assigned to the Bt cluster or equally to both clusters. These results indicate that backcross with Bt has been repeated, and therefore the traits of Bt might be maintained in this study.

Co-structure analysis and genetic associations reveal insights into pinworms (Trypanoxyuris) and primates (Alouatta palliata) microevolutionary dynamics

BackgroundIn parasitism arm race processes and red queen dynamics between host and parasites reciprocally mold many aspects of their genetics and evolution. We performed a parallel assessment of population genetics and demography of two species of pinworms with different degrees of host specificity (Trypanoxyuris multilabiatus, species-specific; and T. minutus, genus-specific) and their host, the mantled howler monkey (Alouatta palliata), based on mitochondrial DNA sequences and microsatellite loci (these only for the host). Given that pinworms and primates have a close co-evolutionary history, covariation in several genetic aspects of their populations is expected.ResultsMitochondrial DNA revealed two genetic clusters (West and East) in both pinworm species and howler monkeys, although population structure and genetic differentiation were stronger in the host, while genetic diversity was higher in pinworms than howler populations. Co-divergence tests showed no congruence between host and parasite phylogenies; nonetheless, a significant correlation was found between both pinworms and A. palliata genetic pairwise distances suggesting that the parasites’ gene flow is mediated by the host dispersal. Moreover, the parasite most infective and the host most susceptible haplotypes were also the most frequent, whereas the less divergent haplotypes tended to be either more infective (for pinworms) or more susceptible (for howlers). Finally, a positive correlation was found between pairwise p-distance of host haplotypes and that of their associated pinworm haplotypes.ConclusionThe genetic configuration of pinworm populations appears to be molded by their own demography and life history traits in conjunction with the biology and evolutionary history of their hosts, including host genetic variation, social interactions, dispersal and biogeography. Similarity in patterns of genetic structure, differentiation and diversity is higher between howler monkeys and T. multilabiatus in comparison with T. minutus, highlighting the role of host-specificity in coevolving processes. Trypanoxyuris minutus exhibits genetic specificity towards the most frequent host haplotype as well as geographic specificity. Results suggest signals of potential local adaptation in pinworms and further support the notion of correlated evolution between pinworms and their primate hosts.

Genogeography of norway spruce (Picea abies (L.) Karst.) according to the analysis of cytoplasmic DNA

Norway spruce (Picea abies (L.) Karst.) is one of the main forest-forming species in Belarus. It plays important economic, ecological and social roles. The spruce forest of the region is characterized by a complex history of the formation of its population genetic structure. The aim of this study was the genogeographic analysis of P. abies populations and the description of regional features of its gene pool in Belarus. Molecular genetic analysis of microsatellite (SSR) loci of chloroplast DNA and mt15-D02 locus of mitochondrial DNA of Norway spruce was carried out for samples from 57 naturally originated forest stands. We identified 19 allelic variants of the Pt63718, Pt26081, Pt71936 cpDNA loci and two allelic variants of mt15-D02 mtDNA. The geographical distribution of the alleles has been described and the regional features of the genogeographic differentiation of the spruce forests have been considered. The southern border of the continuous distribution area of P. abies and its island localities lie in the south of Belarus (Brest and Gomel regions). The frequency of occurrence of individual allelic variants of cpDNA SSR loci has the most pronounced deviations from the average values for the whole country in those regions. Analysis of cpDNA showed the presence of certain regional features of the genogeographic structure of the spruce forest in the “south-north” and “west-east” directions. According to mitochondrial DNA analysis higher concentration of P. abies trees of southern (Carpathian) origin is observed in the southwest of Belarus. On the contrary northern (Boreal) origin dominates in the rest of the country. The results of performed genogeographic analysis of Norway spruce populations can serve as a basis for improving the forest seed zoning of the tree species.

Signs of Genetic and Morphometric Population Differentiation in Small Planctivorous Seabird, Parakeet Auklet Aethia psittacula, Reinforces Linkage between Population Structure and Migratory Strategy

Study of population genetic structure is essential for insight in species biology, but mechanisms of its formation and factors influencing it remain insufficiently understood. Here we analyzed differentiation among populations in small colonial seabird of North Pacific, the Parakeet Auklet Aethia psittacula, which was previously considered as a monomorphic species. We compare our results with data on congeneric species to investigate the most important factors affecting the process of population differentiation in Aethini. We analyzed morphometric measurements, mitochondrial DNA control region fragment and microsatellite loci from six Parakeet Auklet colonies spanning the breeding range. Although results of microsatellite variability analysis did not reveal differences between birds from different colonies, results of control region variability and morphometric analyses testified for a slight but significant differentiation between birds from the Aleutian Islands and other parts of their range. They were significantly smaller in most linear parameters measured and had higher body condition (expressed as the scaled mass index). The results of mtDNA analysis and discrepancy between different types of genetic markers indicated that birds from Aleutian Islands and from the other parts of their breeding range probably originated from different refuges and the differentiation of mitochondrial lineages between them took place around 100 000 years ago. Our results and conclusions from the comparison with congeneric species indicated that foraging and migration patterns seem to determine population structure in small planktivorous alcids, with panmixia in highly mobile species, clear population differentiation in resident species and intermediate population differentiation in more dispersive species.

First report on embryonic and larval development of 2n/3n mosaic sterlet

Mosaicism is frequently observed in aquaculture practices, and it adversely affects the production as well as the restoration programme of the sturgeon. The purpose of the present study was the induction of 2n/3n mosaic in sterlet, Acipenser ruthenus L., and compare their embryonic and larval development with diploid control sterlet. Microsatellite DNA loci genotyping was conducted for the identification of the genotypes and parentage analysis. Embryonic development was monitored in experimental groups at every 24 h interval. Identification of individual stages of embryonic development was recorded based on a 36-degree scale of development. Additionally, the BW and body length (LT) of experimental fishes were taken during 110 days of the rearing period. The Fulton’s condition coefficient (F), length-weight parameters, and specific growth rate (SGR) coefficient were calculated. The analysis of embryonic development of the 2n/3n mosaic and the diploid control group did not show differences. However, higher mortality (88%) was observed in 2n/3n mosaic groups in comparison to the diploid control groups (55%). BW and body length of 2n/3n mosaic sterlet were slightly lower than the diploid control sterlet, but the differences were not statistically significant. F analysis did not confirm a lower growth performance of the fishes in the 2n/3n mosaic group. Microsatellite DNA loci genotyping confirmed both the incidence of polyspermy and retention of the second polar body. This paper presents the first report on embryonic development and growth performance of 2n/3n mosaic sturgeons.

Influence of the degree of homozygosity of STR-loci on the fertility of thoroughbred horses

Purpose: to study the effect of the level of homozygosity and inbreeding on the fecundity of thoroughbred mares.Materials and methods. A total of 3662 heads of breeding sows from leading stud farms of the Russian Federation were selected for the analysis. The influence of the homozygosity level on 17 microsatellite DNA loci on the main indices of reproduction of thoroughbred mares, such as the safe yield of foals and the number of fetal years, was analyzed in the article. All mares in the experimental sample had at least three years of breeding use. Individual fecundity rates and the number of homozygous loci in the STR profile were calculated for each horse.Results. The highest live foal yields (75.92%) had sows with homozygosity levels of 62.78-69.02%, and the lowest foal yields (45.73%) were recorded in mares with the highest homozygosity levels (75.28-76.92%). The maximum foal yield (65.85%) was determined in sows with an inbreeding rate of 4.1% or more, with a productive longevity of 6.26 fetal years on average. Analysis of the data showed that the level of inbreeding had almost no effect on the yield of live foals (R=0.010 at P>0.05), but had a negative correlation with the number of fruiting years (R=-0.092 at P<0.005).Conclusion. Estimation of homozygosity level of thoroughbred horses is especially relevant, as this breed has been perfected by purebred breeding method only for more than thirty years. In the thoroughbred horse breed, it is necessary to create a system of maintaining heterozygosity as well as the diversity of genotypes through the organization of breeding work.

Population structure and genetic diversity of non-native aoudad populations

The aoudad (Ammotragus lervia Pallas 1777) is an ungulate species, native to the mountain ranges of North Africa. In the second half of the twentieth century, it was successfully introduced in some European countries, mainly for hunting purposes, i.e. in Croatia, the Czech Republic, Italy, and Spain. We used neutral genetic markers, the mitochondrial DNA control region sequence and microsatellite loci, to characterize and compare genetic diversity and spatial pattern of genetic structure on different timeframes among all European aoudad populations. Four distinct control region haplotypes found in European aoudad populations indicate that the aoudad has been introduced in Europe from multiple genetic sources, with the population in the Sierra Espuña as the only population in which more than one haplotype was detected. The number of detected microsatellite alleles within all populations (< 3.61) and mean proportion of shared alleles within all analysed populations (< 0.55) indicates relatively low genetic variability, as expected for new populations funded by a small number of individuals. In STRUCTURE results with K = 2–4, Croatian and Czech populations cluster in the same genetic cluster, indicating joined origin. Among three populations from Spain, Almeria population shows as genetically distinct from others in results, while other Spanish populations diverge at K = 4. Maintenance of genetic diversity should be included in the management of populations to sustain their viability, specially for small Czech population with high proportion of shared alleles (0.85) and Croatian population that had the smallest estimated effective population size (Ne = 5.4).

A novel interpretation of speciation, hybridization, and genetic population structure of the stone crabsMenippe mercenaria(Say, 1817–1818) andM. adinaWilliams &amp; Felder, 1986 (Decapoda: Brachyura: Menippidae)

AbstractMitochondrial DNA cytochrome oxidase (COI) and microsatellite DNA loci were used to better explain the speciation events, history of hybridization, and genetic population structure of the stone crabs Menippe adinaWilliams &amp; Felder, 1986 and M. mercenaria (Say, 1817–1818). A survey of a 670-bp COI sequence of 711 stone crabs collected from Texas to North Carolina and from Belize, Central America showed the presence of two well-defined mtDNA lineages, Lin-A and Lin-B. Based on molecular clock calibrations of a published study these lineages shared a common ancestor between 1.5 to 1.8 million years. Lin-A was evident throughout the range of the two Menippe species, but Lin-B was found only in the eastern Gulf of Mexico and does not represent any of the two species. Our findings refute the claim that the eastern Gulf hybrid zone is the product of hybridization between M. adina and M. mercenaria. We propose that the hybrid zone is instead a relic of introgressive hybridization between the M. mercenaria of eastern Gulf stone crab nDNA Lin-AA that carries Lin-A and the new nDNA Lin-BB that carries Lin-B, forming the hybrid nDNA Lin-AB. Lin-B emerged from a founder effect in the Okefenokee Trough and introgressed into the eastern Gulf. There is no Lin-B in the Atlantic, hence no hybridization in that region. Using stone crab-specific microsatellite markers we found no evidence of an ongoing hybridization in the eastern Gulf and this region cannot be called a hybrid zone since hybridization here ceased probably soon after the last glacial episode. The microsatellite-marker analyses also suggested that the stone crab was geographically divided into four genetic clusters by three barriers to gene flow, the strongest of which is the one between the two species, M. adina and M. mercenaria, around Cape San Blas, Apalachicola Bay, Florida.

Investigating the genetic structure of the parasites Anisakis pegreffii and A. berlandi (Nematoda: Anisakidae) in a sympatric area of the southern Pacific Ocean waters using a multilocus genotyping approach: first evidence of their interspecific hybridization

The southern Pacific Ocean, off the New Zealand coast, has been reported as one sympatric area of the two parasite species Anisakis pegreffii and A. berlandi. Here, a multilocus genotyping approach, based on a panel of eleven DNA microsatellite (SSR) loci plus the sequences analysis of the nuclear nas10 nDNA and the mitochondrial mtDNA cox2 gene loci, was applied to a total of N = 344 adults and larvae of Anisakis spp. from cetacean and fish species, respectively. Out of the newly scored SSR loci, Anisl 15 and Anisl 2 showed fixed alternative alleles between A. pegreffii and A. berlandi resulting as 100% diagnostic loci. Out of SSRs Anisl 00314 and Anisl 7 previously disclosed, two additional loci, i.e., Anisl 4 and Anisl 22, were found to be sex-linked. The Bayesian genotypes clustering approach (STRUCTURE) allowed identification, with a 100% of probability value, N = 208 specimens to the "pure parental" A. pegreffii, N = 133 to the "pure parental" A. berlandi, while one adult and two larval stages showed mixed ancestry between the two groups having, in all cases, a Q-value = 0.50. NEWHYBRIDS analysis assigned (100% of probability) those specimens to their F1 hybrid category. This represents the first evidence of contemporary hybridization between the two parasite species in a sympatric area. The pairwise FST values estimated at intraspecific and interspecific level, inferred from both SSR loci and mitochondrial mtDNA cox2 sequences, have also demonstrated the existence of two distinct panmictic units in this study area, corresponding respectively to A. pegreffii and A. berlandi. The results obtained support the useful application of a multilocus approach in the identification of sibling species and their hybrid categories in sympatric areas. The possible use of sex-linked SSR loci of the two species of the A. simplex (s. l.), for sex determination of their larval stages, is also suggested.

Pattern of genetic structure of the common stream fish, Neolissochilus soroides (Pisces: Cyprinidae), addresses the importance of protected areas in eastern Thailand.

The well-known presence of mahseers, Neolissochilus soroides (Cyprinidae), in forested streams in eastern Thailand has attracted many visitors to protected areas for several decades. Because of its historical high abundance, this species was never considered of conservation concern. In this study, the authors revealed that mahseers are very limited to upstream areas in mountains facing the Gulf of Thailand and are now solely confined to habitats within protected areas. The fish were sampled below seven waterfalls in four national parks. All individuals were analysed using a fragment of the mitochondrial DNA cytochrome b gene and eight nuclear microsatellite DNA loci to uncover spatial genetic patterns. Cytochrome b data showed very low genetic diversity but indicated strong genetic differentiation between the most distant Klong Kaeo (KK) population and the other populations. The more variable microsatellite DNA markers showed moderate level of genetic diversity compared to other mahseers but revealed limited gene flow among all locations (overall FST =0.25, P < 0.05). In addition, significant correlation was found between genetic and geographic distances (P < 0.05). Genetic bottleneck analyses provided an insight into evolutionary history in N. soroides that may have experienced past reduction in population size. As eastern Thailand is a relatively heavily populated region, habitat modification in lowland areas is inevitable, and it will have consequences for species that prefer fast-flowing and clear water. Protected areas therefore provide valuable sanctuaries for N. soroides in headwater streams.

Conservation genetic assessment of the paleback darter, Etheostoma pallididorsum, a narrowly distributed endemic in the Ouachita Highlands, Arkansas, USA

Abstract The paleback darter, Etheostoma pallididorsum, is considered imperilled and has recently been petitioned for listing under the Endangered Species Act. Previous allozyme‐based studies found evidence of a small effective population size, warranting conservation concern. The objective of this study was to assess the population dynamics and the phylogeographical history of the paleback darter, using a multilocus microsatellite approach and mitochondrial DNA. The predictions of this study were that: paleback darter populations will exhibit low genetic diversity and minimal gene flow; population structure will correspond to the river systems from which the samples are derived; reservoir dams impounding the reaches between the Caddo and Ouachita rivers would serve as effective barriers to gene flow; and the Caddo and Ouachita rivers are reciprocally monophyletic. Microsatellite DNA loci revealed significant structure among sampled localities (global Fst = 0.17, P &lt; 0.001), with evidence of two distinct populations representing the Caddo and Ouachita rivers. However, Bayesian phylogeographical analyses resulted in three distinct clades: Caddo River, Ouachita River, and Mazarn Creek. Divergence from the most recent ancestor shared among the river drainages was estimated at 60 Kya. Population genetic diversity was relatively low (He = 0.65; mean alleles per locus, A = 6.26), but was comparable with the population genetic diversity found in the close relatives slackwater darter, Etheostoma boschungi (He = 0.65; A = 6.74), and Tuscumbia darter, Etheostoma tuscumbia (He = 0.57; A = 5.53). These results have conservation implications for paleback darter populations and can be informative for other headwater specialist species. Like other headwater species with population structuring and relatively low genetic diversity, the persistence of paleback darter populations is likely to be tied to the persistence and connectivity of local breeding and non‐breeding habitat. These results do not raise conservation concern for a population decline; however, the restricted distribution and endemic status of the species still renders paleback darter populations vulnerable to extirpation or extinction.

Features of Picea abies (L.) Karst. population structure formation on the territory of Belarus

One of the main forest forming tree species in Belarus is the European spruce (Picea abies (L.) Karst.). The formation of European spruce forest population genetic structure took place under the influence of migration flows from different refugia during the postglacial period. For the genogeographic study of P. abies 25 isozyme genes (Aat-1, Aat-2, Adh, Gdh, Idh-1, Idh-2, Mdh-1, Mdh-2, Mdh-3, Skdh, 6-Pgd-1, 6-Pgd-2, 6-Pgd-3, Lap-1, Lap-2, Sdh, Gpi, Hk, Me, Dia-1, Dia-2, Dia-4, Pgm-1, Pgm-2, Fl-Est) of nuclear DNA (analysis was carried out in 10 populations), 3 microsatellite loci (Pt63718, Pt26081, Pt71936) of chloroplast DNA (57 populations were considered) and 1 microsatellite locus (mt15-D02) of mitochondrial DNA (56 populations were studied) were used. As a result, 82 allelic variants of isozyme genes, 19 allelic variants of chloroplast DNA loci and 2 allelic variants of mitochondrial DNA locus were found. The spatial distribution of the alleles was defined and the regional features of the genogeographic differentiation of the spruce forest were considered. The presence of two migration flows representatives (southern and northern) in Belarus was confirmed. It was shown that the highest concentration of P. abies trees with southern (Carpathian) origin is observed in the southwest of the country. Clinal variability was revealed for a number of markers in the directions from south to north and from west to east. In general the data obtained are consistent with the results of studies based on the analysis of the spatial distribution of the cone scales traits.

High gene flow in polar cod (Boreogadus saida) from West-Svalbard and the Eurasian Basin.

The current and projected environmental change of the Arctic Ocean contrasts sharply with the limited knowledge of its genetic biodiversity. Polar cod Boreogadus saida (Lepechin, 1774) is an abundant circumpolar marine fish and ecological key species. The central role of polar cod in the Arctic marine food web warrants a better understanding of its population structure and connectivity. In this study, the genetic population structure of 171 juveniles, collected from several fjords off West-Svalbard (Billefjorden, Hornsund and Kongsfjorden), the northern Sophia Basin and the Eurasian Basin of the Arctic Ocean, was analysed using nine DNA microsatellite loci. Genetic analyses indicated moderate to high genetic diversity, but absence of spatial population structure and isolation-by-distance, suggesting ongoing gene flow between the studied sampling regions. High levels of connectivity may be key for polar cod to maintain populations across wide spatial scales. The adaptive capacity of the species will be increasingly important to face challenges such as habitat fragmentation, ocean warming and changes in prey composition. In view of a limited understanding of the population dynamics and evolution of polar cod, a valuable next step to predict future developments should be an integrated biological evaluation, including population genomics, a life-history approach, and habitat and biophysical dispersal modelling.