Distribution by Scientific Domains

Kinds of Heterozygosity

  • average heterozygosity
  • compound heterozygosity
  • expected heterozygosity
  • genetic heterozygosity
  • high heterozygosity
  • individual heterozygosity
  • mean heterozygosity
  • multilocu heterozygosity
  • observed heterozygosity

  • Terms modified by Heterozygosity

  • heterozygosity level
  • heterozygosity value

  • Selected Abstracts

    Effectiveness of Conservation Targets in Capturing Genetic Diversity

    Maile C. Neel
    We used empirical data from four rare plant taxa to assess these consequences in terms of how well allele numbers ( all alleles and alleles occurring at a frequency openface>0.05 in any population ) and expected heterozygosity are represented when different numbers of populations are conserved. We determined sampling distributions for these three measures of genetic diversity using Monte Carlo methods. We assessed the proportion of alleles included in the number of populations considered adequate for conservation, needed to capture all alleles, and needed to meet an accepted standard of genetic-diversity conservation of having a 90,95% probability of including all common alleles. We also assessed the number of populations necessary to obtain values of heterozygosity within ±10% of the value obtained from all populations. Numbers of alleles were strongly affected by the number of populations sampled. Heterozygosity was only slightly less sensitive to numbers of populations than were alleles. On average, currently advocated conservation intensities represented 67,83% of all alleles and 85,93% of common alleles. The smallest number of populations to include all alleles ranged from 6 to 17 ( 42,57% ), but <0.2% of 1000 samples of these numbers of populations included them all. It was necessary to conserve 16,29 ( 53,93% ) of the sampled populations to meet the standard for common alleles. Between 20% and 64% of populations were needed to reliably represent species-level heterozygosity. Thus, higher percentages of populations are needed than are currently considered adequate to conserve genetic diversity if populations are selected without genetic data. Resumen: Cualquier acción de conservación que preserve algunas poblaciones y no otras tendrá consecuencias genéticas. Utilizamos datos empíricos de cuatro taxones de plantas raras para evaluar estas consecuencias en términos de lo bien representados que están los números de alelos ( todos los alelos ocurriendo a una frecuencia>0.05 en cualquier población ) y la heterocigosidad esperada cuando se conservan diferentes números de poblaciones. Las distribuciones de muestreo de estas tres medidas de la diversidad genética fueron determinadas utilizando métodos Monte Carlo. Evaluamos la proporción de alelos incluida en números de poblaciones: consideradas adecuadas para la conservación; requeridas para capturar todos los alelos; y las requeridas para alcanzar un estándar de conservación de diversidad genética aceptable del 90,95% de probabilidad de incluir todos los alelos comunes. También evaluamos el número de poblaciones necesarias para obtener valores de heterocigosidad que caigan dentro de ±10% del valor obtenido de todas las poblaciones. Los números de alelos fueron afectados significativamente por el número de poblaciones muestreadas. La heterocigosidad solo fue ligeramente menos sensible a los números de poblaciones de lo que fueron los alelos. Las intensidades de conservación propugnadas actualmente representaron en promedio el 67,83% de todos los alelos y el 85,93% de los alelos comunes. El menor número de poblaciones para incluir a todos los alelos varió de 6 a 17 ( 42,57% ), pero <0.2% de 1000 muestras de esos números de poblaciones los incluyó a todos. Fue necesario conservar de 16 a 29 ( 53,93% ) de las poblaciones muestreadas para alcanzar el estándar para los alelos comunes. Se requirió entre 20% y 64% de las poblaciones para representar la heterocigosidad a nivel de especie confiablemente. Por lo tanto, se requieren mayores porcentajes de poblaciones que los actualmente considerados adecuados para conservar la diversidad genética si las poblaciones son seleccionadas sin datos genéticos. [source]


    EVOLUTION, Issue 12 2004
    Mikael Puurtinen
    Abstract The amount and distribution of genetic variability in host populations can have significant effects on the outcome of host-parasite interactions. We studied the effect of mating system and genetic variability on susceptibility of Lymnaea stagnalis snails to trematode parasites. Mating system of snails from eight populations differing in the amount of genetic variability was manipulated, and self- and cross-fertilized offspring were exposed to naturally occurring trematode parasites in a controlled lake experiment. Susceptibility of snails varied between populations, but mating-system treatment did not have a significant effect. Heterozygosity of snails was negatively correlated with the probability of trematode infection, however, suggesting that parasitic diseases may pose a serious threat to populations lacking genetic variability. [source]

    LDL-receptor mutations in Europe,

    HUMAN MUTATION, Issue 6 2004
    George V.Z. Dedoussis
    Abstract Familial hypercholesterolemia (FH) is a clinical definition for a remarkable increase of cholesterol serum concentration, presence of xanthomas, and an autosomal dominant trait of either increased serum cholesterol or premature coronary artery disease (CAD). The identification of the low-density lipoprotein (LDL)-receptor (LDLR) as the underlying cause and its genetic characterization in FH patients revealed more insights in the trafficking of LDL, which primarily transports cholesterol to hepatic and peripheral cells. Mutations within LDLR result in hypercholesterolemia and, subsequently, cholesterol deposition in humans to a variable degree. This confirms the pathogenetic role of LDLR and also highlights the existence of additional factors in determining the phenotype. Autosomal dominant FH is caused by LDLR deficiency and defective apolipoprotein B-100 (APOB), respectively. Heterozygosity of the LDLR is relatively common (1:500). Clinical diagnosis is highly important and genetic diagnosis may be helpful, since treatment is usually effective for this otherwise fatal disease. Very recently, mutations in PCSK9 have been also shown to cause autosomal dominant hypercholesterolemia. For autosomal recessive hypercholesterolemia, mutations within the so-called ARH gene encoding a cellular adaptor protein required for LDL transport have been identified. These insights emphasize the crucial importance of LDL metabolism intra- and extracellularly in determining LDL-cholesterol serum concentration. Herein, we focus on the published European LDLR mutation data that reflect its heterogeneity and phenotypic penetrance. Hum Mutat 24:443,459, 2004. © 2004 Wiley-Liss, Inc. [source]

    Analysis of two Chinese yak (Bos grunniens) populations using bovine microsatellite primers

    Wang Minqiang
    Summary Two Chinese domestic yak populations representing the Plateau type and the Huanhu Alpine type were analysed with 12 bovine microsatellite primers. All primer pairs functioned in the yak genome and polymorphism was found at all loci. The allele size ranges and frequencies of the two yak populations were similar and there was considerable overlap with the allele size ranges observed in cattle. Data for European cattle breeds was obtained from the Cattle Diversity Database (CaDBase) to interpret the heterozygosity and genetic distance estimates in yak populations. Heterozygosity estimated for the two yak populations was comparable with that of European cattle while Nei's Genetic Distance DA between the two yak populations was less than distances between the most closely related German cattle breeds. Bovine microsatellite primers proved to be a valuable tool for characterization of yak populations. Zusammenfassung Untersuchungen von zwei chinesischen Yak (Bos grunniens) Herden mittels Primersequenzen von Rindermikrosatelliten Primersequenzen von Rindermikrosatelliten wurden verwendet, um zwei chinesische Yak-Herden zu analysieren, eine vom Plateau-Typ und eine andere vom Huanhu-Bergtyp. Alle 12 Primerpaare führten zu polymorphen Amplifikationsprodukten mit den DNA-Proben der Yaks. Der Allelgrößenbereich und die Allelfrequenzen aller 12 Marker waren in den beiden Yak-Herden sehr ähnlich. Zum Vergleich wurden Typisierungsergebnisse der 12 Mikrosatellitengenorte von 15 europäischen Rinderassen aus der Rinderdiversitätsdatenbank CaDBase entnommen. Ein großer Teil der Yak-Allele hatte die gleiche Größe wie beim Rind und auch der geschätzte Heterozygotiegrad der beiden Yak-Populationen war vergleichbar mit dem durchschnittlichen Heterozygotiegrad der 15 Rinderrassen. Die genetische Distanz (Nei's DA) zwischen beiden Yak-Herden wurde jedoch geringer geschätzt als zwischen zwei Paaren eng verwandter Rinderrassen. Die Ergebnisse zeigen, dass Sequenzinformationen von Rindermikrosatellitenprimern für die Charakterisierung von Yak-Populationen auf der molekularen Ebene nützlich sein können. [source]

    Temporal variation of heterozygosity-based assortative mating and related benefits in a lesser kestrel population

    Abstract Heterozygosity as a target of mate choice has received much attention in recent years and there is growing evidence supporting its role in the evolution of mate preferences. In this study we analyse mating patterns in relation to heterozygosity in a lesser kestrel (Falco naumanni) population intensively monitored over six study years (2002,2007). The magnitude of heterozygosity-based assortative mating varied over time, being particularly patent in the last study years (2006, 2007). We have found evidence that this mating pattern entails both direct and indirect-genetic benefits. Clutch size increased with female heterozygosity and more heterozygous males raised a higher number of fledglings particularly in those years when the strength of the heterozygosity-based assortative mating was markedly higher. In the last study year, parent,offspring correlation of heterozygosity was stronger and higher than the expected if individuals would have randomly mated with respect to heterozygosity. Overall, our results offer empirical support to the heterozygous mate hypothesis of sexual selection but suggest that genetic diversity may act as a temporally variable target for mate choice. [source]

    NEWS AND VIEWS: Heterozygosity of the Yellowstone wolves

    MOLECULAR ECOLOGY, Issue 16 2010
    First page of article [source]

    Heterozygosity,fitness correlations and associative overdominance: new detection method and proof of principle in the Iberian wild boar

    MOLECULAR ECOLOGY, Issue 13 2009
    Heterozygosity-fitness correlations (HFC) may result from a genome-wide process , inbreeding , or local effects within the genome. The majority of empirical studies reporting HFCs have attributed correlations to inbreeding depression. However, HFCs are unlikely to be caused by inbreeding depression because heterozygosity measured at a small number of neutral markers is unlikely to accurately capture a genome-wide pattern. Testing the strengths of localized effects caused by associative overdominance has proven challenging. In their current paper, Amos and Acevedo-Whitehouse present a novel test for local HFCs. Using stochastic simulations, they determine the conditions under which single-locus HFCs arise, before testing the strength of the correlation between the neutral marker and a linked gene under selection in their simulations. They used insights gained from simulation to statistically investigate the likely cause of correlations between heterozygosity and disease status using data on bovine tuberculosis infections in a wild boar population. They discover that a single microsatellite marker is an excellent predictor of tuberculosis progression in infected individuals. The results are relevant for wild boar management but, more generally, they demonstrate how single-locus HFCs could be used to identify coding loci under selection in free-living populations. [source]

    Heterozygosity,fitness correlations and their relevance to studies on inbreeding depression in threatened species

    MOLECULAR ECOLOGY, Issue 18 2008
    Abstract The majority of reported multilocus heterozygosity,fitness correlations (HFCs) are from large, outbred populations, and their relevance to studies on inbreeding depression in threatened populations is often stressed. The results of such HFC studies conducted on outbred populations may be of limited application to threatened population management, however, as bottlenecked populations exhibit increased incidence of inbreeding, increased linkage disequilibrium, reduced genetic diversity and possible effects of historical inbreeding such as purging. These differences may affect both our ability to detect inbreeding depression in threatened species, and our interpretation of the underlying mechanisms for observed heterozygosity,fitness relationships. The study of HFCs in outbred populations is of interest in itself, but the results may not translate directly to threatened populations that have undergone severe bottlenecks. [source]

    MHC diversity and the association to nematode parasitism in the yellow-necked mouse (Apodemus flavicollis)

    MOLECULAR ECOLOGY, Issue 7 2005
    Abstract In vertebrates, the genes of the major histocompatibility complex (MHC) are among the most debated candidates accounting for co-evolutionary processes of host,parasite interaction at the molecular level. The exceptionally high allelic polymorphism found in MHC loci is believed to be maintained by pathogen-driven selection, mediated either through heterozygous advantage or rare allele advantage (= frequency dependent selection). While investigations under natural conditions are still very rare, studies on humans or mice under laboratory conditions revealed support for both hypotheses. We investigated nematode burden and allelic diversity of a functional important MHC class II gene (DRB exon2) in free-ranging yellow-necked mice (Apodemus flavicollis). Twenty-seven distinct Apfl -DRB alleles were detected in 146 individuals with high levels of amino acid sequence divergence, especially at the antigen binding sites (ABS), indicating selection processes acting on this locus. Heterozygosity had no influence on the infection status (being infected or not), the number of different nematode infections (NNI) or the intensity of infection, measured as the individual faecal egg count (FEC). However, significant associations of specific Apfl -DRB alleles to both nematode susceptibility and resistance were found, for all nematodes as well as in separate analyses of the two most common nematodes. Apodemus flavicollis individuals carrying the alleles Apfl -DRB*5 or Apfl -DRB*15 revealed significantly higher FEC than individuals with other alleles. In contrast, the allele Apfl -DRB*23 showed a significant association to low FEC of the most common nematode. Thus, our results provide evidence for pathogen-driven selection acting through rare allele advantage under natural conditions. [source]

    Isolation and characterization of Brachymystax lenok microsatellite loci and cross-species amplification in Hucho spp. and Parahucho perryi

    E. Froufe
    Abstract We isolated and characterized eight polymorphic microsatellite markers for Brachymystax lenok (Pallas, 1773) from genomic libraries enriched for (GATA)n, (GACA)n and (ATG)n microsatellites. The number of alleles per locus ranged from two to 17. Heterozygosity ranged from 0.2 to 0.95. In addition, cross-species amplification was successful for seven loci in Hucho hucho, eight in H. taimen and seven in Parahucho perryi. [source]

    Characterization of microsatellite loci in the spruce bark beetle Ips typographus (Coleoptera: Scolytinae)

    A. Sallé
    Abstract Ips typographus is an economically important pest of Norway spruce stands. We developed five polymorphic microsatellite markers using a biotin enrichment protocol. The number of alleles ranged from three to 11 per locus and no strong evidence for null alleles was found. Heterozygosity ranged from 0.3 to 0.97. These markers could be useful tools to study the population structure and genetic consequences of I. typographus population outbreaks. [source]

    Genome-wide genetic diversity of ,Nici', the DNA source for the CHORI-260 turkey BAC library and candidate for whole genome sequencing

    ANIMAL GENETICS, Issue 3 2009
    L. D. Chaves
    Summary Vertebrate whole genome sequence assembly can benefit from a priori knowledge of variability in the target genome, with researchers often selecting highly inbred individuals for sequencing. However, for most species highly inbred research lines are lacking, requiring the use of an outbred individual(s). Here we examined the source DNA [Nicholas inbred (Nici)] of the CHORI-260 turkey bacterial artificial chromosome (BAC) library through analysis of microsatellites and BAC sequences. Heterozygosity of Nici was compared with that of individuals from several breeder lines. Seventy-eight microsatellites were screened for polymorphism in a total of 43 birds, identifying an average individual heterozygosity of 0.39, with Nici at 0.35. Additional loci (total of 147) were examined on a subset of individuals to obtain better genome coverage. The mean heterozygosity for this subset was 0.33 with Nici at 0.31. Examination of approximately 200 kb of genome sequence identified SNPs in the order of one per 200 bp in Nici. These data suggest that the heterozygosity of Nici is comparable to other birds of selected breeder lines and that whole genome sequencing would result in an abundant resource of genome-wide polymorphisms. [source]

    Association between SNP Heterozygosity and Quantitative Traits in the Framingham Heart Study

    Didahally R. Govindaraju
    Summary Associations between multilocus heterozygosity and fitness traits, also termed heterozygosity and fitness correlations (HFCs), have been reported in numerous organisms. These studies, in general, indicate a positive relationship between heterozygosity and fitness traits. We studied the association between genome-wide heterozygosity at 706 non-synonymous and synonymous SNPs and 19 quantitative traits, including morphological, biochemical and fitness traits in the Framingham Heart Study. Statistically significant association was found between heterozygosity and systolic and diastolic blood pressures as well as left ventricular diameter and wall thickness. These results suggest that heterozygosity may be associated with traits, such as blood pressure that closely track environmental variations. Balancing selection may be operating in the maintenance of heterozygosity and the major components of blood pressure and hypertension. Genome wide SNP heterozygosity may be used to understand the phenomenon of dominance as well as the evolutionary basis of many quantitative traits in humans. [source]

    Double Heterozygosity with Mutations Involving both the GJB2 and GJB6 Genes is a Possible, but very Rare, Cause of Congenital Deafness in the Czech Population

    P. Seeman
    Summary Mutations in the GJB2 gene are the most common cause of prelingual, autosomal recessive, sensorineural hearing loss worldwide. Nevertheless, 10% to 50% of patients with prelingual nonsyndromic deafness only carry one mutation in the GJB2 gene. Recently a large 342 kb deletion named ,(GJB6-D13S1830) involving the GJB6 gene was reported in Spanish and French deafness patients, either in a homozygous state or in combination with a monoallelic GJB2 mutation. No data have been reported about the frequency of this mutation in central Europe. Thirteen Czech patients with prelingual nonsyndromic sensorineural deafness carrying only one pathogenic mutation in the GJB2 gene were tested for the presence of the ,(GJB6-D13S1830) mutation. One patient with a GJB2 mutation (313del14) also carried the ,(GJB6-D13S1830). This is the first reported Czech case, and probably also the first central European case, of prelingual deafness due to mutations involving both the GJB2 and GJB6 genes. In addition, the ,(GJB6-D13S1830) was not detected in 600 control chromosomes from Czech individuals with normal hearing. We show that in the Czech Republic the ,(GJB6-D13S1830) is not the second most common causal factor in deafness patients heterozygous for a single GJB2 mutation, and that ,(GJB6-D13S1830) is very rare in central Europe compared to reports from Spain, France and Israel. [source]

    The dice of fate: the csd gene and how its allelic composition regulates sexual development in the honey bee, Apis mellifera

    BIOESSAYS, Issue 10 2004
    Martin Beye
    Perhaps 20% of known animal species are haplodiploid: unfertilized haploid eggs developinto males and fertilized diploid eggs into females. Sex determination in such haplodiploid species does not rely on a difference in heteromorphic sex chromosome composition but the genetic basis has been elucidated in some hymenopteran insects (wasps, sawflies, ants, bees). In these species, the development into one sex or the others depends on an initial signal whether there is only one allele or two different alleles of a single gene, the complementary sex determiner (csd), in the zygotic genome. The gene has been most-recently identified in the honey bee and has been found to encode an arginine serine-rich (SR) type protein. Heterozygosity generates an active protein that initiates female development while hemizygosity/homozygosity results in a non-active CSD protein and default male development. I will discuss plausible models of how the molecular decision of male and female is made and implemented. Comparison to hierarchies of dipteran insects suggests that SR-type protein has facilitated the differentiation of sex-determining systems and hierarchies. BioEssays 26:1131,1139, 2004. © 2004 Wiley Periodicals, Inc. [source]

    Genetic diversity measures of the bovine Alberes breed using microsatellites: variability among herds and types of coat colour,

    J. Casellas
    Summary The Alberes population is a native bovine breed of Catalonia with an unclear origin, which historically some authors have assumed as being composed of two different colour varieties (black and fawn). Sixteen microsatellite loci were analysed, all of them included in the AIRE2066 European Concerted Action list. Overall expected and observed heterozygosities reached values of 0.649 and 0.662, respectively. Genetic differences among black and fawn varieties were not significant (FST = 0.007), and therefore the population is a single variety with a great colour gradation. On the contrary, we detected significant genetic differences among herds (FST = 0.026; p < 0.001), showing a genetic heterogeneity over short geographical distances. The number of migrants per generation among pairs of herds oscillates between 1.46 (Roig and Freixe herds) and 5.62 (Castanyers and Roig herds). Moreover, inbreeding and bottleneck situations can be rejected. The Alberes breed has been grouped within the Cantabrian trunk, closely related to the Asturiana de la Montaña and Alistana breeds, although some other breeds may also have influenced the population along its history. Zusammenfassung Die Rasse Alberes ist eine einheimische Rinderrasse Kataloniens mit unklarer Herkunft, von der historisch einige Autoren vermuten, dass sie eine Zusammensetzung aus zwei verschiedenen Farbvarianten ist (schwarz und hellbraun). Es wurden sechzehn Mikrosatelliten, die alle aus der ,,AIRE2066 European Concerted Action list,, stammen, analysiert. Der gesamte erwartete und beobachtete Heterozygotiegrad erreichte Werte von 0,649 beziehungsweise 0,662. Die genetischen Unterschiede zwischen den schwarzen und hellbraunen Varianten waren nicht signifikant (Fst = 0,007), so dass die Rasse als eine einzige Variante mit einer großen Farbabstufung gilt, die wir erhalten müssen. Im Gegensatz dazu entdeckten wir signifikante genetische Unterschiede innerhalb der Herden (Fst = 0,026, p < 0,001), die eine genetische Heterogenität innerhalb kurzer geografischer Distanzen aufzeigten. Die Anzahl an Migranten pro Generation innerhalb der Herdpaare schwankt zwischen 1,46 (Roig - und Freixe -Herden) und 5,62 (Castanyers - und Roig -Herden). Darüberhinaus kann Inzucht und eine Flaschenhalssituation zurückgewiesen werden. Die Rasse Alberes wurde innerhalb eines Cantabrischen Astes gruppiert, in enger Verwandtschaft zu den Rassen Asturiana de la Montaña und Alistana, obwohl im Laufe der Geschichte auch einige andere Rassen die Population beeinflusst haben könnten. [source]

    Genetic diversity and population size: island populations of the common shrew, Sorex araneus

    MOLECULAR ECOLOGY, Issue 10 2007
    Abstract Populations of many species are currently being fragmented and reduced by human interactions. These processes will tend to reduce genetic diversity within populations and reduce individual heterozygosities because of genetic drift, inbreeding and reduced migration. Conservation biologists need to know the effect of population size on genetic diversity, as this is likely to influence a population's ability to persist. Island populations represent an ideal natural experiment with which to study this problem. In a study of common shrews (Sorex araneus) on offshore Scottish islands, 497 individuals from 13 islands of different sizes and 6 regions on the mainland were trapped and genotyped at eight microsatellite loci. Previous genetic work had revealed that most of the islands in this study were highly genetically divergent from one another and the mainland. We found that most of the islands exhibited lower genetic diversity than the mainland populations. In the island populations, mean expected heterozygosity, mean observed heterozygosity and mean allelic richness were significantly positively correlated with log island size and log population size, which were estimated using habitat population density data and application of a Geographic Information System. [source]

    Cryptic behaviours, inverse genetic landscapes, and spatial avoidance of inbreeding in the Pacific jumping mouse

    MOLECULAR ECOLOGY, Issue 4 2007
    Abstract Although the behaviour of individuals is known to impact the genetic make-up of a population, observed behavioural patterns do not always correspond to patterns of genetic structure. In particular, philopatric or dispersal-limited species often display lower-than-expected values of relatedness or inbreeding suggestive of the presence of cryptic migration, dispersal, or mating behaviours. I used a combination of microsatellite and mark,recapture data to test for the influence of such behaviours in a dispersal-limited species, the Pacific jumping mouse, within a semi-isolated population over three seasons. Despite short dispersal distances and a low rate of first generation migrants, heterozygosities were high and inbreeding values were low. Dispersal was male-biased; interestingly however, this pattern was only present when dispersal was considered to include movement away from paternal home range. Not unexpectedly, males were polygynous; notably, some females were also found to be polyandrous, selecting multiple neighbouring mates for their single annual litter. Patterns of genetic structure were consistent with these more inconspicuous behavioural patterns. Females were more closely related than males and isolation by distance was present only in females. Furthermore, detailed genetic landscapes revealed the existence of strong, significant negative correlations, with areas of low genetic distance among females overlapping spatially with areas of high genetic distance among males. These results support the hypothesis that the detected cryptic components of dispersal and mating behaviour are reducing the likelihood of inbreeding in this population through paternally driven spatial mixing of male genotypes and polyandry of females. [source]

    A microsatellite-based estimation of clonal diversity and population subdivision in Zostera marina, a marine flowering plant

    MOLECULAR ECOLOGY, Issue 2 2000
    T. B. H. Reusch
    Abstract We examined the genetic population structure in eelgrass (Zostera marina L.), the dominant seagrass species of the northern hemisphere, over spatial scales from 12 km to 10 000 km using the polymorphism of DNA microsatellites. Twelve populations were genotyped for six loci representing a total of 67 alleles. Populations sampled included the North Sea (four), the Baltic Sea (three), the western Atlantic (two), the eastern Atlantic (one), the Mediterranean Sea (one) and the eastern Pacific (one). Microsatellites revealed substantial genetic variation in a plant group with low allozyme diversity. Average expected heterozygosities per population (monoclonal populations excluded) ranged from 0.32 to 0.61 (mean = 0.48) and allele numbers varied between 3.3 and 6.7 (mean = 4.7). Using the expected frequency of multilocus genotypes within populations, we distinguished ramets from genetic individuals (i.e. equivalent to clones). Differences in clonal diversity among populations varied widely and ranged from maximal diversity (i.e. all ramets with different genotype) to near or total monoclonality (two populations). All multiple sampled ramets were excluded from further analysis of genetic differentiation within and between populations. All but one population were in Hardy,Weinberg equilibrium, indicating that Zostera marina is predominantly outcrossing. From a regression of the pairwise population differentiation with distance, we obtained an effective population size Ne of 2440,5000. The overall genetic differentiation among eelgrass populations, assessed as , (a standardized estimate of Slatkin's RST) was 0.384 (95% CI 0.34,0.44, P < 0.001). Genetic differentiation was weak among three North Sea populations situated 12,42 km distant from one another, suggesting that tidal currents result in an efficient exchange of propagules. In the Baltic and in Nova Scotia, a small but statistically significant fraction of the genetic variance was distributed between populations (, = 0.029,0.053) at scales of 15,35 km. Pairwise genetic differentiation between European populations were correlated with distance between populations up to a distance of 4500 km (linear differentiation-by-distance model, R2 = 0.67). In contrast, both Nova Scotian populations were genetically much closer to North Sea and Baltic populations than expected from their geographical distance (pairwise , = 0.03,0.08, P < 0.01). A biogeographical cluster of Canadian with Baltic/North Sea populations was also supported using a neighbour-joining tree based on Cavalli,Sforza's chord distance. Relatedness between populations may be very different from predictions based on geographical vicinity. [source]

    Isolation and description of eight polymorphic microsatellite loci for the winged-kelp Alaria nana

    JULIE D. COLLENSArticle first published online: 1 APR 200
    Abstract Here I report on the isolation of eight microsatellites from the winged-kelp, Alaria nana, using an enrichment protocol. Using 55 individuals from Tatoosh, WA and complete data at all loci, loci displayed 6,11 alleles with observed and expected heterozygosities of 0.396,0.754, and 0.769,0.872 respectively. Using an isolated, randomly breeding subset, six of the eight loci were determined to be in Hardy,Weinberg equilibrium. These markers will be useful in assessing population structure in the intertidal and inferring patterns of dispersal. [source]

    Isolation and characterization of microsatellite primers for Ceratosolen fusciceps, the fig-pollinating wasp of Ficus racemosa, and amplification in two populations

    Abstract Ten microsatellite loci were isolated and characterized for Ceratosolen fusciceps, the pollinating wasp of Ficus racemosa, based on individuals from Xishuangbanna (China) and Chiangmai (Thailand). High levels of variation were found among loci for both populations; allelic number varied from two to 18 (respectively from two to 22), expected heterozygosities ranged from 0.362 to 0.890 (respectively from 0.430 to 0.930). [source]

    Isolation and characterization of 11 tetranucleotide microsatellite loci in the Egyptian mongoose (Herpestes ichneumon)

    Abstract We report the isolation of 11 polymorphic tetranucleotide microsatellite loci in the Egyptian mongoose (Herpestes ichneumon). In a sample of 27 individuals, we observed between 4 and 7 alleles per locus and their observed and expected heterozygosities ranged from 0.37 to 0.85 and from 0.44 to 0.79, respectively. All genotypic frequencies conformed to Hardy,Weinberg equilibrium expectations and there were no instances of linkage disequilibrium detected between pairs of loci. [source]

    Development and characterization of 30 polymorphic microsatellite markers for the Atlantic surfclam, Spisula solidissima (Dillwyn, 1817)

    Abstract Thirty polymorphic microsatellite markers were developed for the Atlantic surfclam, Spisula solidissima, from an enriched library and characterized in 24 clams from a wild population. The number of alleles ranged from 3 to 16 per locus. The expected and observed heterozygosities ranged from 0.1942 to 0.9238 and 0.0833 to 0.875 respectively. Six loci showed significant (P < 0.05 after Bonferroni correction) deviation from Hardy,Weinberg equilibrium, probably because of the presence of null alleles. Three primer pairs amplified duplicated loci with two involving tandem mini-satellite repeats. Most of the microsatellite markers developed here should be useful for genetic studies in this species. [source]

    Eleven new microsatellite loci for the tiger rattlesnake (Crotalus tigris)

    Abstract Eleven microsatellite loci were isolated from an enriched genomic library from the tiger rattlesnake Crotalus tigris. Average observed heterozygosities in two populations were 0.456 and 0.427, respectively, and mean number of alleles were 7.54 (range 2,14) and 4.72 (range 2,13) respectively. No evidence of linkage disequilibrium was found across pairs of loci. The markers will be used in a long-term study examining the potential effects of urbanization on population dynamics and connectivity of this species in the mountain ranges surrounding Tucson, Arizona. [source]

    Isolation and characterization of microsatellite loci for storm-petrels

    Abstract Primers were developed for 10 microsatellite loci for two species of Oceanodroma storm-petrels. Variability was tested in 27 O. castro and 22 O. monteiroi from the Azores, and 24 O. leucorhoa from Norway. At least six loci amplified reliably and were polymorphic in each species. The number of alleles per locus averaged 4.6, and observed heterozygosities averaged 0.41. Most primers also yielded polymerase chain reaction products in O. tethys, O. hornbyi and Pterodroma phaeopygia. These loci are being used to assay population genetic structure in storm-petrels. [source]

    Characterization of single nucleotide polymorphism markers for the green sea turtle (Chelonia mydas)

    Abstract We present data on 29 new single nucleotide polymorphism assays for the green sea turtle, Chelonia mydas. DNA extracts from 39 green turtles were used for two methods of single nucleotide polymorphism discovery. The first approach employed an amplified fragment length polymorphism technique. The second technique screened a microsatellite library. Allele-specific amplification assays were developed for high-throughput single nucleotide polymorphism genotyping and tested on two Pacific C. mydas nesting populations. Observed heterozygosities ranged from 0 to 0.95 for a Hawaiian population and from 0 to 0.85 for a Galapagos population. Each of the populations had one locus out of Hardy,Weinberg equilibrium, SSCM2b and SSCM5 for Hawaii and Galapagos, respectively. No loci showed significant genotypic linkage disequilibrium across an expanded set of four Pacific nesting populations. However, two loci, SSCM4 and SSCM10b showed linkage disequilibrium across three populations indicating possible association. [source]

    Polymorphic microsatellite loci in the widespread amphidromous goby Sicyopterus lagocephalus and cross-genus amplification among Sicydiinae

    Abstract Microsatellite DNA markers were isolated in an amphidromous goby (Sicyopterus lagocephalus) from a partial genomic library enriched for AC repeats. Eight microsatellites were highly polymorphic with six to 33 alleles per locus and expected heterozygosities ranging from 0.53 to 0.97. Cross-species amplifications were performed within the sub-family Sicydiinae by genotyping individuals from two species of the genus Cotylopus. Some of these loci were successfully amplified and showed polymorphism in the second genus. [source]

    Isolation and characterization of 11 polymorphic microsatellite loci in the whitegirdled goby (Pterogobius zonoleucus) and cross-species amplification in the serpentine goby (P. elapoides)

    Abstract Eleven polymorphic microsatellite markers were developed from a (CA)n -enrichment library of the whitegirdled goby (Pterogobius zonoleucus). Polymorphism at these loci ranged from 2 to 12 alleles, and observed and expected heterozygosities from 0.05 to 0.90 and from 0.05 and 0.86, respectively. All loci conformed to Hardy,Weinberg equilibrium, with no significant linkage disequilibrium between all locus pairs. Cross-species amplification tests were successful in P. elapoides, and most loci were polymorphic. These microsatellite markers will be useful in further population genetic studies of both species. [source]

    Isolation and characterization of microsatellite loci in tropical forage Stylosanthes capitata Vogel

    M. O. SANTOS
    Abstract Stylosanthes capitata is an important tropical pasture legume. Knowledge of genetic diversity and structure of S. capitata populations is of great importance for the conservation and germplasm management of this species. Thus, eight microsatellite markers were developed from an S. capitata -enriched library. They were characterized in 20 accessions from the germplasm collection of the Empresa Brasileira de Pesquisa Agropecuária (Embrapa). The observed and expected heterozygosities ranged from 0.16 to 0.85 and from 0.40 to 0.85, respectively. These microsatellites are the first set of molecular markers from this species and will contribute towards studies of genetic diversity, conservation and breeding of S. capitata. [source]

    Development and characterization of 14 polymorphic microsatellite loci in the raccoon tick (Ixodes texanus)

    Abstract Fourteen polymorphic microsatellite loci were developed for the raccoon tick (Ixodes texanus). Three multiplexed panels comprising the loci were developed and 50 ticks collected from two infected raccoons (Procyon lotor) were genotyped. The number of alleles per locus ranged from five to 22, and single locus heterozygosities ranged from 0.46 to 0.94. Future research will further our understanding of I. texanus biology and help in elucidating the effects of life-history variation on parasite population genetic structure, using I. texanus as a model organism. [source]