Genetic structure of an isolated group of the indigenous population of northern Siberia--Nganasans (Tavgiitsi) of Taymyr. I. History, erythrocyte and serum blood systems, isoenzymes]

Nganasans is a small samodyen-speaking ethnic group originated from several clans of reindeer hunters. Pedigree studies revealed no consanguineous matings of uncle-niece, aunt-nephew, first cousins type among 120 families studied. Rather rarely mating between second cousins could be observed. The reviewed traditional kindship system based on bilateral exogamy is an explanation. Data on 12 blood systems and 6 red cell enzymes distribution in two main localities almost totally studied have been presented. No A2, r, K, MS alleles were observed. Hgh frequencies of Ns, R2, Fya, Jka, Gm1 have been found. Diegoa was seen in only one family. Polymorphism on PGM1, 6-PGD, AK and AP, monomorphism on LDH and MDH has been observed.     

Genetic structure of 2 isolated populations of native inhabitants of Sibiria (Northern Altaics) according to the results of a study of blood groups and isoenzymes

The article comprises the results of the investigation of the frequencies of alleles of 9 gene loci controlling the blood groups, isoenzymes in populations and subpopulations of Cumandinians and Chelkanians. The presence of alleles A2 r(cde) and K at low concentrations was discovered in both groups. The method of genetic distances was used for the investigation of the inter- and intragroup divergence. With respect to certain loci a considerable variation of allelic frequencies from village to village was established.     

Genetic variability and population structure in Cypriot chukar partridges (Alectoris chukar cypriotes) as determined by microsatellite analysis

For the first time, microsatellite loci were used to study the genetic structure in Alectoris chukar cypriotes. Four of the ten tested microsatellite loci were found to be polymorphic in 33 individuals from four regions of Cyprus. The differentiation test between all the pairs of samples gave non-differentiation exact P values in every case (P>0.05). The posterior probability distribution on the number of source populations indicated only one population (P=0.977); also, a high Bayes factor value (130.020) was obtained. Posterior co-assignment probabilities (measures of similarity) for all pairs of individuals ranged from 0.984 to 1. The global F_IS value was not found to be significant. A recent bottleneck of the Cypriot total partridge population is suggested and this is supported by a significant Wilcoxon test (P=0.031) under the Infinite Alleles Model (IAM) and shifted mode in the alleles frequencies distribution. The results suggest that all the individuals studied belong to only one randomly mating (panmictic) population, with low genetic variation and evidence of recent effective population size reduction (genetic bottleneck). A big hunting pressure exists on the island and about 200,000 captive-bred birds are released every year; these individuals are descendant from a small number of eggs collected in a small area of Cyprus in 1986 and this founder effect could explain the existence of a bottleneck and the low genetic variability.     

Genetic diversity and population structure of the serpentine endemic Calystegia collina (Convolvulaceae) in northern California

We used enzyme electrophoresis to evaluate genetic diversity in 32 populations of Calystegia collina, a clonal plant species endemic to serpentine outcrops in northern California (USA). Of 34 loci examined 56% were polymorphic, but on average only 17% were polymorphic within local populations. Neither the total number of alleles nor the number of multilocus genotypes differed significantly between populations in small vs. large serpentine outcrops. Genetic and geographic distances between populations were positively correlated, but this relationship was not significantly affected by the isolation of serpentine outcrops. Populations were highly differentiated (F(st) = 0.417) and little genetic variation was explained by geographic region or serpentine outcrop.Observed heterozygosity within populations almost always exceeded Hardy-Weinberg expectations. In many populations, all 30 sample ramets were uniformly heterozygous at one or more loci yet were genetically variable at other loci. These results imply that many C. collina populations originate from one or a few genetic founders, with little recruitment from seeds. Genetic variation within uniformly heterozygous populations must be the product of multiple, closely related founders or somatic mutations within the population. We conclude that vegetative reproduction, perhaps coupled with somatic mutation, helps maintain genetic diversity in these isolated but long-lived populations.     

Genetic diversity and population structure of native,naturalized, and cultivated Salix purpurea

Tree Genetics & Genomes - Sandalwood (Santalum album L.) is a valuable commodity in the international trade due to its use in fragrance and essential oil industries. In the present study, a...     

Genetic population structure of the lionfish Pterois miles (Scorpaenidae, Pteroinae) in the Gulf of Aqaba and northern Red Sea

The aim of this study is to reveal gene flow between populations of the coral reef dwelling lionfish Pterois miles in the Gulf of Aqaba and northern Red Sea. Due to the fjord-like hydrography and topology of the Gulf of Aqaba, isolation of populations might be possible. Analysis of 5' mitochondrial control region sequences from 94 P. miles specimens detected 32 polymorphic sites, yielding 38 haplotypes. Sequence divergence among different haplotypes ranged from 0.6% to 9.9% and genetic diversity was high (h=0.85, pi=1.9%). AMOVA indicates panmixia between the Gulf of Aqaba and northern Red Sea, but analysis of migration pattern shows an almost unidirectional migration originating from the Red Sea.     

Genetic diversity,population structure and gene flow in native populations of a proposed biocontrol agent (Cornops aquaticum)

The semiaquatic grasshopper Cornops aquaticum is native to South America, with a distribution as far south as the Argentinean pampas and as far north as the Gulf of Mexico. This grasshopper is being proposed as a form of biological control agent for the invasive aquatic macrophyte (Eichhornia crassipes) in South Africa. The results of a molecular study (six microsatellite loci) conducted on 11 C. aquaticum populations is presented. Unlike in contiguous mainland South American populations, we found genetic diversity to be lowest in a South African quarantine population, with reduced values in two other isolated populations from South America. In addition, F_st/R_st/analysis of molecular variance and Bayesian cluster analysis suggested high levels of connectivity between mainland populations. The implications of these findings and their relationship to those of a recent morphological study suggest that the suitability of C. aquaticum as a form of biocontrol might be unpredictable at best. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 666–676.     

Mating system and population genetic structure of an androdioecious tree, Fraxinus lanuginosa Koidz. (Oleaceae) in northern Japan

Models for the maintenance of androdioecy have suggested that selfing of hermaphrodites decreases the frequency of males in a population (the "male frequency"). To test this hypothesis, we used electrophoretic allozyme methods to study the mating system and population genetics of an androdioecious tree, Fraxinus lanuginosa, which exhibits large variations in male frequency among subpopulations in central Hokkaido (northern Japan). We estimated the outcrossing rates by using seeds assayed at three polymorphic loci, and found that the multilocus outcrossing rate (t(m)) increased with increasing male frequency (q) (t(m) = 0.69 to 0.99, q = 0.11 to 0.59). Fixation indices (F(j)) estimated from these t(m) values ranged from 0.006 to 0.185, and were significantly greater than zero in plots with a low male frequency (q or = 0.47). However, fixation indices at the late life stage (F(a)) were not significantly different from zero at five loci (F(a) = 0.056 to 0.101, q = 0.11 to 0.61), and the F(a) values were lower than the F(j) values in several of the plots where both values were measured. These results indicate that inbreeding depression substantially decreases the proportion of selfed progeny in partially self-fertilising subpopulations. A theoretical model for the maintenance of androdioecy showed expected male frequencies significantly lower than the observed values in plots with high male frequency (q = 0.59 to 0.61), although the differences between the expected and observed values of male frequencies were not significant in plots with intermediate or low male-frequencies (q = 0.11 to 0.47). In this paper, the factors are discussed that affect variations in the male frequency among subpopulations of F. lanuginosa based on these findings.     

Population structure of the forest Nentsi. V. F-statistics, genetic distances and the average heterozygosity (compared to the Nganasani)

Aspects of population structure within two of the least disintegrated "anthropological isolates" in north-western (forest Nentsi) and north-central (Nganasani) Siberia were analysed on the basis of 14 polymorphic loci. The mean FIS values were found to be 0.008 in the forest Nentsi and -0.038 in the Nganasani. The negative FIS in the latter may be due to avoidance of close inbreeding. This is not the case with the Forest Nentsi who prefer matings of the uncle-niece and first cousin's type. The mean RST(FST) values of 0.026 for the forest Nentsi and 0.009 for less heterogeneous Nganasani fall within the range of values found in subdivided human groups with a similar pattern of material culture and economy. Analysis of covariance and variance matrices containing gene frequencies for seven forest Nentsi and three Nganasani subdivisions indicate that the population structure of both groups is the product of the counterbalancing action of genetic drift and migration. Pairwise genetic and geographic distance matrices between subpopulations within both groups are highly correlated, allowing us to ascribe more than 90 percent of variation among subdivisions of the Nganasani and almost 70 percent in the forest Nentsi to the effects of geographic barriers, namely distance. Mean locus heterozygosity was found to be higher in the forest Nentsi (0.332) than in the Nganasani (0.286) reflecting pronounced difference in their histories.     

Genetic variation and population structure in central and isolated populations of balsam fir, Abies balsamea (Pinaceae)

Genetic variation and spatial genetic structure in balsam fir (Abies balsamea) were examined in two isolated populations in Iowa and Minnesota thought to be paleorefugia and in two ecologically central populations in old-growth forests of Upper Michigan. Overall levels of genetic variability at 22 allozyme loci were lower than that found in most conifer species (H(o) values ranged from 0.005 in the isolated populations to 0.025 in the central populations). The mean F(IS) value (0.154) was larger than usually found in conifers and suggests moderate levels of inbreeding. The mean F(ST), an estimate of genetic diversity among populations, was 3.7% of the total diversity, a value lower than the mean for conifers. Nm, the number of migrants per generation, was 6.5, suggesting either some gene flow among populations or a lack of genetic differentiation. Spatial autocorrelation analysis revealed a moderately patchy structure, with gene flow distances of 30-70 m in the central populations and at least 10 m in the isolated populations. The future of the ecologically central populations depends on maintenance of an intact forest mosaic. The low genetic variability in the small, isolated populations suggests that habitat fragmentation has led to a reduction in evolutionary potential and that the future viability of these populations will likely require active management in the face of global climate change.     

A genetic analysis of group movement in an isolated population of tree-roosting bats

Group fission is an important dispersal mechanism for philopatric adults. In Cypress Hills Interprovincial Park, Saskatchewan, tree-roosting big brown bats (Eptesicus fuscus) exhibit fission-fusion roosting behaviour. During 2004-2007, the majority of females previously resident to roosting area 1 (RA1) moved to a new roosting area (RA4). We examined how genetic relationships, inferred from data for microsatellite loci and mitochondrial DNA, influenced new roost area (RA) selection during 2006 when colony members were split between the RAs. We found that females who moved to RA4 had higher average relatedness than those that remained in RA1. We found that nearly all females belonging to matrilines with high average relatedness moved to RA4 while females from matrilines with low average relatedness were split between the two RAs. These results suggest that closely related maternal kin preferentially move to new RAs. However, daily roosting preferences within a RA are not based on genetic relationships probably because daily roosting associations between kin and non-kin are used to ensure adequate roost group size. Studying the effects of kinship on the fission and movements of groups not only enhances our understanding of social behaviour and population genetics but also informs conservation decisions.     

Genetic population structure of the Dakota skipper (Lepidoptera: Hesperia dacotae): A North American native prairie obligate

A range-wide survey of Dakotaskipper (Hesperia dacotae) populationsassessed levels of genetic variability andgeographic scale of population structure inthis species of conservation concern. Thisspecies exists on isolated patches of nativetall- and mixed-grass prairie within a highlymodified landscape dominated by agriculture. It has been extirpated from the southernportion of its range and has sufferedrange-wide declines. Nine populations weresampled from western Minnesota, eastern SouthDakota, and southern Manitoba. Starch gelelectrophoresis was used to resolve 21 isozymeloci in 278 Dakota skippers. Dakota skipperpopulations were approximately as variable asother lepidopterans found in isolated habitats. Genetic distances indicated that Manitobapopulations were somewhat distinct from ones inMinnesota and South Dakota. Isolation-by-distance was detected range-wideand among the seven southern-most populations. Genetically effective immigration rates weresmall at both range-wide and regional scalesand effective populations sizes were lowsuggesting that Dakota skipper populations aregenetically isolated from one another, althoughthey were likely more connected in the recentpast. Genotype assignment tests revealed twoclusters of populations in Minnesota and SouthDakota that were not apparent from theisolation-by-distance results. Significantheterozygote deficiencies relative toHardy-Weinberg expectations and high inbreedingcoefficients suggest structure within samplelocations. Management recommendations includethe maximization of effective population sizein each Dakota skipper population to offset theeffects of drift and habitat corridors in somecases. Habitat management should consider thewithin-site population structure and possibletemporal population structure detected in thisstudy.     

Genetic and morphological variability in a population of Diphyllobothrium dendriticum (Nitzsch, 1824)

Plerocercoids of Diphyllobothrium dendriticum were isolated from whitefish (Coregonus clupeaformis) from McGregor Lake, Alberta. Adult D. dendriticum were obtained by infection of golden hamsters (Mesocricetus auratus). Analysis of morphological variables indicated high variability and some overlap with D. latum. Correlations in morphology were due to the covariance of shape variables. Isozyme analysis also showed high variability, with two thirds of the enzymes studied being polymorphic. Correlations with morphology indicate a relationship between rare patterns for malate dehydrogenase and esterase and increased size of adults. Southern hybridisation with ribosomal gene probes produced two common patterns and a rare intermediate form, indicating that the species is variable even within a local population. Correlations between rDNA pattern type and morphological variables supported the hypothesis of a genetic base for the morphological variability.     

Genetic analysis of the population structure of socially organized oystercatchers (Haematopus ostralegus) using microsatellites

On the island of Schiermonnikoog (The Netherlands), the breeding population of oystercatchers can be divided into two groups: 'residents' and 'leapfrogs', based on their distinct social characteristics and limited probabilities of status change between breeding seasons. In order to investigate whether this social organization has caused local genetic differentiation, leapfrogs and residents were compared at eight polymorphic microsatellite loci. No significant genetic subdivision between residents and leapfrogs was observed (theta = 0.0000; 95% confidence interval (CI), -0.0027-0.0033), indicating that the oystercatcher population on the island of Schiermonnikoog has to be considered as one panmictic unit. Investigation of three additional locations in the northern part of The Netherlands did not reveal significant genetic population subdivision either (theta = -0.0005; 95% CI, -0.0045-0.0037), despite the fact that adult osytercatchers show extreme fidelity to their breeding localities. These results indicate panmixis and considerable levels of gene flow within the northern part of The Netherlands. Thus, the results from genetical analyses do not seem to be in agreement with observational data on the dispersal behaviour of breeding individuals. It is argued that the lack of population structure, locally on Schiermonnikoog as well as across larger geographical distances, is to be attributed to high levels of gene flow through dispersal of juvenile birds.     

Genetic structure of a lotic population of Burkolderia (Pseudomonas) cepacia.

The genetic structure of a population of Burkholderia (Pseudomonas) cepacia isolated from a southeastern blackwater stream was investigated by using multilocus enzyme electrophoresis to examine the allelic variation in eight structural gene loci. Overall, 213 isolates were collected at transect points along the stream continuum, from both the sediments along the bank and the water column. Multilocus enzyme electrophoresis analysis revealed 164 distinct electrophoretic types, and the mean genetic diversity of the entire population was 0.574. Genetic diversity values did not vary spatially along the stream continuum. From a canonical discriminant analysis, Mahalonobis distances (measurements of genetic similarity between populations) revealed significant differences among the subpopulations at the sediment sampling points, suggesting bacterial adaptation to a heterogeneous (or patchy) microgeographical environment. Multilocus linkage disequilibrium analysis of the isolates revealed only limited association between alleles, suggesting frequent recombination, relative to binary fission, in this population. Furthermore, the dendrogram created from the data of this study and the allele mismatch distribution are typical of a population characterized by extensive genetic mixing. We suggest that B. cepacia be added to the growing list of bacteria that are not obligatorily clonal.     

RAPD analysis of genetic diversity and population structure of Elymus sibiricus (Poaceae) native to the southeastern Qinghai-Tibet Plateau, China

Genetic diversity of Elymus sibiricus (Poaceae) was examined in eight populations from the southeast Qinghai-Tibet Plateau. We detected 291 RAPD polymorphic loci in 93 samples. The percentage of polymorphic bands (PPB) was 79%. Genetic diversity (H(E)) was 0.264, effective number of alleles (N(E)) was 1.444, Shannon's information index (H(O)) was 0.398, and expected Bayesian heterozygosity (H(B)) was 0.371. At the population level, PPB = 51%, N(E) = 1.306, H(E) = 0.176, I = 0.263, and H(B) = 0.247. A high level of genetic differentiation was detected based on Nei's genetic diversity analysis (G(ST) = 32.0%), Shannon's index analysis (33.7%), and the Bayesian method (θ(B) = 33.5%). The partitioning of molecular variance by AMOVA demonstrated significant genetic differentiation within populations (60%) and among populations (40%). The average number of individuals exchanged between populations per generation (N(m)) was 1.06. The populations were found to share high levels of genetic identity. No significant correlation was found between geographic distance and pairwise genetic distance (r = 0.7539, P = 0.9996). Correlation analysis revealed a significant correlation (r = 0.762) between RAPD H(E) found in this study and ISSR H(E) values from a previous study.     

Population genetics of the people of Iran II. Genetic differentiation and population structure

The genetic structure of six populations of Iran (Turks, Kurds, Lurs, Zabolis, Baluchis and Zoroastrians) was examined using data on blood groups, serum proteins and cell enzymes. Our results show conclusively that there are genetic differences among the six populations and the analysis of superimposed R and S matrices defined Harpending & Jenkins (1973) show by that the dispersion of some of the alleles correspond to the dispersion of the populations. The F_ST estimates are not large enough to favour selection on any of the loci studied. The F_IT and F_IS estimates are positive and moderately high suggesting that the genetic differentiation to some extent is influenced by inbreeding.