Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Ancestry

  • african ancestry
  • asian ancestry
  • common ancestry
  • european ancestry
  • genetic ancestry
  • japanese ancestry
  • mixed ancestry
  • shared ancestry

  • Terms modified by Ancestry

  • ancestry informative marker

  • Selected Abstracts

    Ancestry and kinships of native Siberian populations: The HLA evidence

    Tatiana S. Uinuk-Ool
    First page of article [source]

    Cranial Nonmetric Variation and Estimating Ancestry,

    Joseph T. Hefner Ph.D.
    Abstract:, Historically, when predicting the ancestry of human skeletal remains, forensic anthropologists have not fully considered the variation within human populations, but instead have relied on a typological, experience-based approach. Unfortunately, reliance on observer experience has produced a method that is as much an art as it is a science. This research focuses on the frequency distribution and inter-trait correlations of 11 common morphoscopic traits to demonstrate that the experience-based approach to ancestry prediction is indeed an art that is unscientific, because it is unreplicable, unreliable, and invalid. Ten of 11 traits examined had frequency distributions with significant differences (p < 0.001) between groups, but the range in variation of these traits far exceeds previous assumptions. Such within group variation clearly demonstrates that extreme trait expressions are not reliable for estimating ancestry through visual observation alone, but instead that these traits should be analyzed within a statistical framework. [source]

    DNA Sequence Characterization of the FGA STR Locus in the Free State Population of South Africa

    André de Kock Ph.D.
    POPULATION: African (n=52), Mixed Ancestry (n=5), Caucasian (n=4) SAN (n=1). [source]

    Sequence Variations of the Human MPDZ Gene and Association With Alcoholism in Subjects With European Ancestry

    ALCOHOLISM, Issue 4 2009
    Victor M. Karpyak
    Background:,Mpdz gene variations are known contributors of acute alcohol withdrawal severity and seizures in mice. Methods:, To investigate the relevance of these findings for human alcoholism, we resequenced 46 exons, exon,intron boundaries, and 2 kilobases in the 5, region of the human MPDZ gene in 61 subjects with a history of alcohol withdrawal seizures (AWS), 59 subjects with a history of alcohol withdrawal without AWS, and 64 Coriell samples from self-reported nonalcoholic subjects [all European American (EA) ancestry] and compared with the Mpdz sequences of 3 mouse strains with different propensity to AWS. To explore potential associations of the human MPDZ gene with alcoholism and AWS, single SNP and haplotype analyses were performed using 13 common variants. Results:, Sixty-seven new, mostly rare variants were discovered in the human MPDZ gene. Sequence comparison revealed that the human gene does not have variations identical to those comprising Mpdz gene haplotype associated with AWS in mice. We also found no significant association between MPDZ haplotypes and AWS in humans. However, a global test of haplotype association revealed a significant difference in haplotype frequencies between alcohol-dependent subjects without AWS and Coriell controls (p = 0.015), suggesting a potential role of MPDZ in alcoholism and/or related phenotypes other than AWS. Haplotype-specific tests for the most common haplotypes (frequency > 0.05), revealed a specific high-risk haplotype (p = 0.006, maximum statistic p = 0.051), containing rs13297480G allele also found to be significantly more prevalent in alcoholics without AWS compared with nonalcoholic Coriell subjects (p = 0.019). Conclusions:, Sequencing of MPDZ gene in individuals with EA ancestry revealed no variations in the sites identical to those associated with AWS in mice. Exploratory haplotype and single SNP association analyses suggest a possible association between the MPDZ gene and alcohol dependence but not AWS. Further functional genomic analysis of MPDZ variants and investigation of their association with a broader array of alcoholism-related phenotypes could reveal additional genetic markers of alcoholism. [source]

    Ancestry and divergence of subtropical montane forest isolates: molecular biogeography of the genus Abies (Pinaceae) in southern México and Guatemala

    MOLECULAR ECOLOGY, Issue 10 2008
    Abstract The genus Abies has a complex history in southern México and Guatemala. In this region, four closely related species, Abies flinckii, A. guatemalensis, A. hickelii, and A. religiosa, are distributed in fragmented and isolated montane populations. Range-wide genetic variation was investigated across species using cytoplasmic DNA markers with contrasted inheritance. Variation at two maternally inherited mitochondrial DNA markers was low. All species shared two of the nine mitotypes detected, while the remaining seven mitochondrial DNA types were restricted to a few isolated stands. Mitochondrial genetic differentiation across taxa was high (GST = 0.933), it was not related to the taxonomic identity (amova; P > 0.05) of the populations, and it was not phylogeographically structured (GST , NST). In contrast, variation at three paternally inherited chloroplast DNA microsatellites was high. Chloroplast genetic differentiation was lower (GST = 0.402; RST = 0.547) than for mitochondrial DNA, but it was significantly related to taxonomy (amova; P < 0.001), and exhibited a significant phylogeographical structure (GST < RST). Different analyses of population structure indicated that A. flinckii was the most divergent taxon, while the remaining three species formed a relatively homogeneous group. However, a small number of the populations of these three taxa, all located at the limits of their respective ranges or in the Transverse Volcanic Belt, diverged from this main cluster. These trends suggest that the Mesoamerican Abies share a recent common ancestor and that their divergence and speciation is mainly driven by genetic drift and isolation during the warm interglacial periods. [source]

    A Stem Group Brachiopod From The Lower Cambrian: Support For A Micrina (Halkieriid) Ancestry

    PALAEONTOLOGY, Issue 5 2002
    Lars E. Holmer
    The shell structure of the Lower Cambrian Mickwitzia, a bilaterally symmetrical bivalve hitherto doubtfully assigned to the Brachiopoda, confirms that the genus shares characters with linguliform brachiopods. The columnar lamination of its organophosphatic shell is homologous with that characterizing acrotretides. The shell, however, is also pervaded by striated apatitic tubes indistinguishable from those permeating the sclerites of the problematic organophosphatic, laminar,shelled Micrina which is close to Halkieria. No crown group brachiopods have such tubes that are presumed to have contained setae. The presence of both these features in the Mickwitzia shell suggests that the stock is a stem group brachiopod with a halkieriid ancestry. [source]

    Skin Responses to Ultraviolet Radiation: Effects of Constitutive Pigmentation, Sex, and Ancestry

    Jennifer K. Wagner
    Constitutive skin pigmentation and skin responses to ultraviolet radiation were measured on a sample of volunteers (n=250) living in State College, PA, USA. The sample was composed of individuals of European American (n=190), Hispanic (n=45), and East Asian ancestry (n=15). Constitutive pigmentation was measured using the Adjusted Melanin Index (AMI), Erythemal Dose Response (EDR) was measured using the slope of a* at 24 h (,a*), and Melanogenic Dose,Response (MDR) was measured using ,AM, the slope of AMI at 7 d. The relationships between constitutive skin pigmentation, EDR, MDR, sex, age, and ancestry were investigated. European Americans showed a lower constitutive pigmentation, had a significantly higher burn response (EDR), and had a significantly lower tanning response (MDR) than Hispanics and East Asians. No significant difference is seen between Hispanics and East Asians for either constitutive pigmentation or EDR. Constitutive pigmentation in females was slightly lower than in males in all three samples, but the difference was not significant. While no differences were observed in MDR between sexes, males had a stronger EDR than females regardless of population or constitutive pigmentation level, and this difference was significant in European Americans and Hispanics. We observed no age-related differences in any of the populations or measures investigated. We evaluated the relationship between constitutive pigmentation, EDR and MDR. There was a strong inverse correlation between constitutive pigmentation and EDR in the three samples (European Americans, R2=0.176, P < 0.001; Hispanics, R2=0.204, P=0.009; East Asians, R2=0.223, P=0.098) and a strong direct correlation between constitutive pigmentation and MDR in European Americans and Hispanics (European Americans, R2=0.094, P < 0.001; Hispanics, R2=0.164, P=0.012). In other words, persons with lower constitutive pigmentation both burn more and tan less than persons with higher pigmentation. However, after controlling for constitutive pigmentation, EDR and MDR were significantly correlated in European Americans (R2=0.041 P=0.006). Thus, the general observation that persons who burn more tan less is probable because of the common link that these two phenotypes have with constitutive skin pigmentation and, in fact, once pigmentation has been adjusted for, there is a positive correlation between tanning response and burning response in European Americans. [source]

    Molecular Phylogeny and Surface Morphology of Colpodella edax (Alveolata): Insights into the Phagotrophic Ancestry of Apicomplexans

    ABSTRACT. The molecular phylogeny of colpodellids provides a framework for inferences about the earliest stages in apicomplexan evolution and the characteristics of the last common ancestor of apicomplexans and dinoflagellates. We extended this research by presenting phylogenetic analyses of small subunit rRNA gene sequences from Colpodella edax and three unidentified eukaryotes published from molecular phylogenetic surveys of anoxic environments. Phylogenetic analyses consistently showed C. edax and the environmental sequences nested within a colpodellid clade, which formed the sister group to (eu)apicomplexans. We also presented surface details of C. edax using scanning electron microscopy in order to supplement previous ultrastructural investigations of this species using transmission electron microscopy and to provide morphological context for interpreting environmental sequences. The microscopical data confirmed a sparse distribution of micropores, an amphiesma consisting of small polygonal alveoli, flagellar hairs on the anterior flagellum, and a rostrum molded by the underlying (open-sided) conoid. Three flagella were present in some individuals, a peculiar feature also found in the microgametes of some apicomplexans. [source]

    Inferring Continental Ancestry of Argentineans from Autosomal, Y-Chromosomal and Mitochondrial DNA

    Daniel Corach
    Summary We investigated the bio-geographic ancestry of Argentineans, and quantified their genetic admixture, analyzing 246 unrelated male individuals from eight provinces of three Argentinean regions using ancestry-sensitive DNA markers (ASDM) from autosomal, Y and mitochondrial chromosomes. Our results demonstrate that European, Native American and African ancestry components were detectable in the contemporary Argentineans, the amounts depending on the genetic system applied, exhibiting large inter-individual heterogeneity. Argentineans carried a large fraction of European genetic heritage in their Y-chromosomal (94.1%) and autosomal (78.5%) DNA, but their mitochondrial gene pool is mostly of Native American ancestry (53.7%); instead, African heritage was small in all three genetic systems (<4%). Population substructure in Argentina considering the eight sampled provinces was very small based on autosomal (0.92% of total variation was between provincial groups, p = 0.005) and mtDNA (1.77%, p = 0.005) data (none with NRY data), and all three genetic systems revealed no substructure when clustering the provinces into the three geographic regions to which they belong. The complex genetic ancestry picture detected in Argentineans underscores the need to apply ASDM from all three genetic systems to infer geographic origins and genetic admixture. This applies to all worldwide areas where people with different continental ancestry live geographically close together. [source]

    A South African mixed ancestry family with Huntington disease-like 2: Clinical and genetic features

    MOVEMENT DISORDERS, Issue 14 2007
    Soraya Bardien PhD
    Abstract Huntington disease-like 2 (HDL2) is a neurodegenerative disorder caused by an expansion of a CTG repeat in the junctophilin-3 gene (JPH3). A limited number of HDL2 families have been reported, all of apparently Black African ancestry. We report on a South African family that presented with progressive dementia and a movement disorder affecting numerous family members. Genotyping of the JPH3 CTG repeat revealed pathogenic expansions in three affected individuals. Whereas HDL2 is thought to be clinically indistinguishable from Huntington disease (HD), 2 of the patients in this study presented with clinical symptoms that differed substantially from HD; one had myoclonus and the other had Parkinsonism. Moreover, brain magnetic resonance imaging scans of these patients showed imaging features atypical for HD. Mitochondrial DNA and Y-chromosome DNA analysis on a family member showed that his maternal and paternal ancestries are typical of that found among the South African mixed ancestry or colored population. A difference in the distribution of CTG repeats between Caucasian and Black individuals was detected. We conclude that the phenotype of HDL2 is broad and can differ from that of typical HD. The diagnosis therefore should be considered in a wide spectrum of neuropsychiatric and abnormal movement presentations. © 2007 Movement Disorder Society [source]

    Neuropsychiatric movement disorders following streptococcal infection

    K G Walker MB BS
    The aim of this study was to describe post-streptococcal movement disorders that form part of the acute rheumatic fever complex. The clinical records of patients diagnosed with Sydenham's chorea were analyzed retrospectively to investigate epidemiology, the significance of socioeconomic deprivation, clinical manifestations, treatments, outcomes, long-term morbidity, and disease evolution. Forty-two patients (21 males, 21 females) were diagnosed with Sydenham's chorea. The median presentation age was 9 years 8 months (range 3y 5mo to 13y 2mo). Nineteen patients were of indigenous African ancestry; 23 were of mixed ancestry. All patients lived in poverty and had poor access to medical care. Twelve of the total group had disabling symptoms for longer than 2 years; six of these patients developed paediatric autoimmune neuropsychiatric disorder associated with Streptococcus (Paediatric autoimmune neuropsychiatric disorder associated with Streptococcus [PANDAS]), five Tourette syndrome (TS), and one learning difficulties. Poor outcome was significantly more prevalent in patients of mixed ancestry, in those with a positive family history, previous behavioural problems, or a failure to complete 10 days of penicillin and ,bed-rest'/hospitalization. Sydenham's chorea is one manifestation of post-streptococcal neuropsychiatric movement disorders. This study demonstrates that patients can present with one diagnosis and evolve other neuropsychiatric conditions such as TS and PANDAS. In the South African context, it is important to delineate neuropsychiatric movement disorders associated with streptococcal infections. The potential genetic susceptibility should be explored. [source]

    Effect of pioglitazone on insulin sensitivity, vascular function and cardiovascular inflammatory markers in insulin-resistant non-diabetic Asian Indians

    DIABETIC MEDICINE, Issue 5 2006
    A. Raji
    Abstract Aims To determine the effects of pioglitazone (30 mg once daily for 16 weeks) on insulin sensitivity, insulin-mediated vasodilation, vascular inflammatory markers, fat distribution and lipids in Asian Indians and Caucasians of European ancestry. Methods Cross-sectional study. Eighteen non-diabetic Asian Indians and 17 Caucasians of comparable age (34 ± 3 vs. 36 ± 3 years) and body mass index (26.0 ± 1.2 vs. 24.7 ± 1.0 kg/m2) had measurements of insulin sensitivity (M, insulin clamp at 6 pmol/kg per min), abdominal fat (computed tomographic scan at L4-L5), endothelial-dependent (reactive hyperaemia, RH) and -independent (0.4 mg sublingual nitroglycerin, TNG) vasodilation using brachial artery ultrasound before and after the 2-h clamp at baseline and after pioglitazone therapy. Results Asian Indians were insulin resistant compared with Causasians during the baseline clamp (M = 25.6 ± 1.7 vs. 41.1 ± 2.2 µmol/kg per min, P < 0.0001) and improved significantly after pioglitazone (to 33.9 ± 1.7 µmol/kg per min, P < 0.001). Vasodilatory responses to RH and TNG were similar in Asian Indians and Caucasians at baseline and did not change. Insulin-mediated vasodilation improved after pioglitazone in Asian Indians, but not in Caucasians, and correlated with the change in insulin sensitivity (r = 0.52, P = 0.03). C-reactive protein (CRP) was higher in Asian Indians vs. Caucasians (1.6 ± 0.4 vs. 0.9 ± 0.2 mg/l) and was negatively correlated with insulin sensitivity (r = ,0.53, P = 0.02). In the Asian Indian group, CRP and plasminogen activator inhibitor-1 decreased and adiponectin increased after pioglitazone, but there were no significant changes in total or visceral fat. Conclusions These results demonstrate that insulin-resistant Asian Indians respond favourably to an insulin sensitizer with improvements in insulin sensitivity, cardiovascular and inflammatory risk markers, and vascular responses to insulin. These agents may have a role in decreasing the risk of diabetes and cardiovascular disease in this high-risk population. [source]

    The origins of kingship in early medieval Kent

    Charlotte Behr
    In this article, it is argued that Bede's famous account of the origin and early development of the people and kings of Kent in Historia ecclesiastica (I.15) does not report historical events, but reflects eighth-century concepts of migration-period kingship with mythical links to the Jutes of Scandinavia. Bracteate evidence shows that the veneration of Woden existed in Kent by the sixth century. Support for a contemporary belief in the Scandinavian origin of Kentish kings is found in locally produced bracteates, which imitate Scandinavian styles, and where several recovered from Kentish cemeteries are found in close proximity to places with royal connections. These include the only known Kentish site linked to the veneration of Woden. Evidence suggests that Kentish genealogy reflects a mythical belief in ancestry from Woden, rather than historical descent from Scandinavian Jutes. Finally, it is argued that Kentish bracteates, usually found in exceptionally rich female graves, were worn by high status women. These women may have played a significant role in legitimizing new royal claims. [source]

    Representing genetic variation as continuous surfaces: an approach for identifying spatial dependency in landscape genetic studies

    ECOGRAPHY, Issue 6 2008
    Melanie A. Murphy
    Landscape genetics, an emerging field integrating landscape ecology and population genetics, has great potential to influence our understanding of habitat connectivity and distribution of organisms. Whereas typical population genetics studies summarize gene flow as pairwise measures between sampling localities, landscape characteristics that influence population genetic connectivity are often continuously distributed in space. Thus, there are currently gaps in both the ability to analyze genotypic data in a continuous spatial context and our knowledge of expected of landscape genetic structure under varying conditions. We present a framework for generating continuous "genetic surfaces", evaluate their statistical properties, and quantify statistical behavior of landscape genetic structure in a simple landscape. We simulated microsatellite genotypes under varying parameters (time since vicariance, migration, effective population size) and used ancestry (q) values from STRUCTURE to interpolate a genetic surface. Using a spatially adjusted Pearson's correlation coefficient to test the significance of landscape variable(s) on genetic structure we were able to detect landscape genetic structure on a contemporary time scale (,5 generations post vicariance, migration probability ,0.10) even when population differentiation was minimal (FST,0.00015). We show that genetic variation can be significantly correlated with geographic distance even when genetic structure is due to landscape variable(s), demonstrating the importance of testing landscape influence on genetic structure. Finally, we apply genetic surfacing to analyze an empirical dataset of black bears from northern Idaho USA. We find black bear genetic variation is a function of distance (autocorrelation) and habitat patch (spatial dependency), consistent with previous results indicating genetic variation was influenced by landscape by resistance. These results suggest genetic surfaces can be used to test competing hypotheses of the influence of landscape characteristics on genetic structure without delineation of categorical groups. [source]

    Polymorphisms in the thymidylate synthase promoter and the DNA repair genes XRCC1 and XPD in a Brazilian population

    Renata Canalle
    Abstract Polymorphisms in genes responsible for maintaining genomic integrity are potential modifiers of disease risk. Since considerable interindividual and interethnic variation in DNA repair capacity has been associated with polymorphic alleles, we evaluated the frequency of the 2R/3R variants in the TS promoter, Arg194Trp and Arg399Gln in the XRCC1 gene, and Asp312Asn and Lys751Gln in the XPD gene in 364 healthy individuals from a Brazilian population separated by ethnicity (European ancestry and African ancestry). The genotypes were determined by PCR (TS) or by PCR-RFLP (XRCC1 and XPD). The frequency of the TS 3R allele was 0.56 for whites and 0.51 for nonwhites. In the case of the XRCC1 MspI polymorphism, the allele frequencies were 0.09 for 194Trp in both nonwhites and whites and 0.27 and 0.28 for 399Gln in nonwhites and whites, respectively. For the XPD 312Asn allele, we found a frequency of 0.25 in white individuals, which was significantly different (P = 0.025) from that seen in nonwhites (0.15). Similarly, the 751Gln polymorphic allele of the XPD gene was significantly more frequent (P < 0.002) in whites (0.30) than in nonwhites (0.20). The genotype frequencies were within Hardy,Weinberg equilibrium. We concluded that the genotype and allele frequencies of XPD gene polymorphism differed between white and nonwhite Brazilians, and that the frequencies of the XPD 312Asn and XRCC1 399Gln alleles in this Brazilian population showed ethnic variability when compared with those observed in other populations. Environ. Mol. Mutagen., 2006. © 2006 Wiley-Liss, Inc. [source]

    Proteorhodopsin photosystem gene clusters exhibit co-evolutionary trends and shared ancestry among diverse marine microbial phyla

    Jay McCarren
    Summary Since the recent discovery of retinylidene proteins in marine bacteria (proteorhodopsins), the estimated abundance and diversity of this gene family has expanded rapidly. To explore proteorhodopsin photosystem evolutionary and distributional trends, we identified and compared 16 different proteorhodopsin-containing genome fragments recovered from naturally occurring bacterioplankton populations. In addition to finding several deep-branching proteorhodopsin sequences, proteorhodopsins were found in novel taxonomic contexts, including a betaproteobacterium and a planctomycete. Approximately one-third of the proteorhodopsin-containing genome fragments analysed, as well as a number of recently reported marine bacterial whole genome sequences, contained a linked set of genes required for biosynthesis of the rhodopsin chromophore, retinal. Phylogenetic analyses of the retinal biosynthetic genes suggested their co-evolution and probable coordinated lateral gene transfer into disparate lineages, including Euryarchaeota, Planctomycetales, and three different proteobacterial lineages. The lateral transfer and retention of genes required to assemble a functional proteorhodopsin photosystem appears to be a coordinated and relatively frequent evolutionary event. Strong selection pressure apparently acts to preserve these light-dependent photosystems in diverse marine microbial lineages. [source]


    EVOLUTION, Issue 6 2010
    Scott A. Pavey
    Ecological divergence may result when populations experience different selection regimes, but there is considerable discussion about the role of migration at the beginning stages of divergence before reproductive isolating mechanisms have evolved. However, detection of past migration is difficult in current populations and tools to differentiate genetic similarities due to migration versus recent common ancestry are only recently available. Using past volcanic eruption times as a framework, we combine morphological analyses of traits important to reproduction with a coalescent-based genetic analysis of two proximate sockeye salmon (Oncorhynchus nerka) populations. We find that this is the most recent (,500 years, 100 generations) natural ecological divergence recorded in a fish species, and report that this divergence is occurring despite migration. Although studies of fish divergence following the retreat of glaciers (10,000,15,000 years ago) have contributed extensively to our understanding of speciation, the Aniakchak system of sockeye salmon provides a rare example of the initial stages of ecological divergence following natural colonization. Our results show that even in the face of continued migration, populations may diverge in the absence of a physical barrier. [source]


    EVOLUTION, Issue 4 2010
    Sofia Adolfsson
    Transitions from sexual to asexual reproduction are often coupled with elevations in ploidy. As a consequence, the importance of ploidy per se for the maintenance and spread of asexual populations is unclear. To examine the effects of ploidy and asexual reproduction as independent determinants of the success of asexual lineages, we sampled diploid sexual, diploid asexual, and triploid asexual Eucypris virens ostracods across a European wide range. Applying nuclear and mitochondrial markers, we found that E. virens consists of genetically highly differentiated diploid sexual populations, to the extent that these sexual clades could be considered as cryptic species. All sexual populations were found in southern Europe and North Africa and we found that both diploid asexual and triploid asexual lineages have originated multiple times from several sexual lineages. Therefore, the asexual lineages show a wide variety of genetic backgrounds and very strong population genetic structure across the wide geographic range. Finally, we found that triploid, but not diploid, asexual clones dominate habitats in northern Europe. The limited distribution of diploid asexual lineages, despite their shared ancestry with triploid asexual lineages, strongly suggests that the wider geographic distribution of triploids is due to elevated ploidy rather than to asexuality. [source]


    EVOLUTION, Issue 3 2007
    L. Lacey Knowles
    Patterns of genetic variation can provide valuable insights for deciphering the relative roles of different evolutionary processes in species differentiation. However, population-genetic models for studying divergence in geographically structured species are generally lacking. Since these are the biogeographic settings where genetic drift is expected to predominate, not only are population-genetic tests of hypotheses in geographically structured species constrained, but generalizations about the evolutionary processes that promote species divergence may also be potentially biased. Here we estimate a population-divergence model in montane grasshoppers from the sky islands of the Rocky Mountains. Because this region was directly impacted by Pleistocene glaciation, both the displacement into glacial refugia and recolonization of montane habitats may contribute to differentiation. Building on the tradition of using information from the genealogical relationships of alleles to infer the geography of divergence, here the additional consideration of the process of gene-lineage sorting is used to obtain a quantitative estimate of population relationships and historical associations (i.e., a population tree) from the gene trees of five anonymous nuclear loci and one mitochondrial locus in the broadly distributed species Melanoplus oregonensis. Three different approaches are used to estimate a model of population divergence; this comparison allows us to evaluate specific methodological assumptions that influence the estimated history of divergence. A model of population divergence was identified that significantly fits the data better compared to the other approaches, based on per-site likelihood scores of the multiple loci, and that provides clues about how divergence proceeded in M. oregonensis during the dynamic Pleistocene. Unlike the approaches that either considered only the most recent coalescence (i.e., information from a single individual per population) or did not consider the pattern of coalescence in the gene genealogies, the population-divergence model that best fits the data was estimated by considering the pattern of gene lineage coalescence across multiple individuals, as well as loci. These results indicate that sampling of multiple individuals per population is critical to obtaining an accurate estimate of the history of divergence so that the signal of common ancestry can be separated from the confounding influence of gene flow,even though estimates suggest that gene flow is not a predominant factor structuring patterns of genetic variation across these sky island populations. They also suggest that the gene genealogies contain information about population relationships, despite the lack of complete sorting of gene lineages. What emerges from the analyses is a model of population divergence that incorporates both contemporary distributions and historical associations, and shows a latitudinal and regional structuring of populations reminiscent of population displacements into multiple glacial refugia. Because the population-divergence model itself is built upon the specific events shaping the history of M. oregonensis, it provides a framework for estimating additional population-genetic parameters relevant to understanding the processes governing differentiation in geographically structured species and avoids the problems of relying on overly simplified and inaccurate divergence models. The utility of these approaches, as well as the caveats and future improvements, for estimating population relationships and historical associations relevant to genetic analyses of geographically structured species are discussed. [source]


    EVOLUTION, Issue 6 2006
    Marcus R. Kronforst
    Abstract Introgressive hybridization is an important evolutionary process and new analytical methods provide substantial power to detect and quantify it. In this study we use variation in the frequency of 657 AFLP fragments and DNA sequence variation from 15 genes to measure the extent of admixture and the direction of interspecific gene flow among three Heliconius butterfly species that diverged recently as a result of natural selection for Müllerian mimicry, and which continue to hybridize. Bayesian clustering based on AFLP genotypes correctly delineated the three species and identified four H. cydno, three H. pachinus, and three H. melpomene individuals that were of mixed ancestry. Gene genealogies revealed substantial shared DNA sequence variation among all three species and coalescent simulations based on the Isolation with Migration (IM) model pointed to interspecific gene flow as its cause. The IM simulations further indicated that interspecific gene flow was significantly asymmetrical, with greater gene flow from H. pachinus into H. cydno (2Nm 5 4.326) than the reverse (2Nm 5 0.502), and unidirectional gene flow from H. cydno and H. pachinus into H. melpomene (2Nm 5 0.294 and 0.252, respectively). These asymmetries are in the directions expected based on the genetics of wing patterning and the probability that hybrids of various phenotypes will survive and reproduce in different mimetic environments. This empirical demonstration of extensive interspecific gene flow is in contrast to a previous study which found little evidence of gene flow between another pair of hybridizing Heliconius species, H. himera and H. erato, and it highlights the critical role of natural selection in maintaining species diversity. Furthermore, these results lend support to the hypotheses that phenotypic diversification in the genus Heliconius has been fueled by introgressive hybridization and that reinforcement has driven the evolution of assortative mate preferences. [source]


    EVOLUTION, Issue 2 2006
    R. Brian Langerhans
    Abstract Examples of convergent evolution suggest that natural selection can often produce predictable evolutionary outcomes. However, unique histories among species can lead to divergent evolution regardless of their shared selective pressures,and some contend that such historical contingencies produce the dominant features of evolution. A classic example of convergent evolution is the set of Anolis lizard ecomorphs of the Greater Antilles. On each of four islands, anole species partition the structural habitat into at least four categories, exhibiting similar morphologies within each category. We assessed the relative importance of shared selection due to habitat similarity, unique island histories, and unique effects of similar habitats on different islands in the generation of morphological variation in anole ecomorphs. We found that shared features of diversification across habitats were of greatest importance, but island effects on morphology (reflecting either island effects per se or phylogenetic relationships) and unique aspects of habitat diversification on different islands were also important. There were three distinct cases of island-specific habitat diversification, and only one was confounded by phylogenetic relatedness. The other two unique aspects were not related to shared ancestry but might reflect as-yet-unmeasured environmental differences between islands in habitat characteristics. Quantifying the relative importance of shared and unique responses to similar selective regimes provides a more complete understanding of phenotypic diversification, even in this much-studied system [source]


    EVOLUTION, Issue 5 2004
    M. Alice Pinto
    Abstract The invasion of Africanized honeybees (Apis mellifera L.) in the Americas provides a window of opportunity to study the dynamics of secondary contact of subspecies of bees that evolved in allopatry in ecologically distinctive habitats of the Old World. We report here the results of an 11-year mitochondrial DNA survey of a feral honeybee population from southern United States (Texas). The mitochondrial haplotype (mitotype) frequencies changed radically during the 11-year study period. Prior to immigration of Africanized honeybees, the resident population was essentially of eastern and western European maternal ancestry. Three years after detection of the first Africanized swarm there was a mitotype turnover in the population from predominantly eastern European to predominantly A. m. scutellata (ancestor of Africanized honeybees). This remarkable change in the mitotype composition coincided with arrival of the parasitic mite Varroa destructor, which was likely responsible for severe losses experienced by colonies of European ancestry. From 1997 onward the population stabilized with most colonies of A. m. scutellata maternal origin. [source]

    Morphology and anatomy of anomalous short shoots in Pinus (Pinaceae) and their evolutionary meaning

    FEDDES REPERTORIUM, Issue 3-4 2010
    Veit Martin Dörken Dr.
    Abstract Recent Pinus -species are evergreen and have a typical long shoot/short shoot differentiation. For angiosperms we could show that this type of shoot differentiation is linked to deciduousness (Dörken & Stützel 2009). Evergreen angiosperms with prominent shoot differentiation are derived from deciduous ancestors. The primitive evergreen condition is however characterized by the absence of a shoot differentiation. Here it is therefore analysed if the shoot differentiation in Pinus could be regarded as a reminder of a deciduous ancestry. In such a context Pinus monophylla would be functionally closest to a primitive evergreen angiosperm and represent a nearly perfect secondary adaptation to the needs of an evergreen species. Morphology and anatomy of aberrant short shoots in Pinus -species have been analysed to test this hypothesis. We suppose that the ancestor of Pinus had several needle leaves inserted spirally on a well developed short shoot axis ending in a terminal bud, as it can be found in Larix today (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    A variant of the myosin light chain kinase gene is associated with severe asthma in African Americans

    Carlos Flores
    Abstract Asthma is a complex phenotype influenced by environmental and genetic factors for which severe irreversible structural airway alterations are more frequently observed in African Americans. In addition to a multitude of factors contributing to its pathobiology, increased amounts of myosin light chain kinase (MLCK), the central regulator of cellular contraction, have been found in airway smooth muscle from asthmatics. The gene encoding MLCK (MYLK) is located in 3q21.1, a region noted by a number of genome-wide studies to show linkage with asthma and asthma-related phenotypes. We studied 17 MYLK genetic variants in European and African Americans with asthma and severe asthma and identified a single non-synonymous polymorphism (Pro147Ser) that was almost entirely restricted to African populations and which was associated with severe asthma in African Americans. These results remained highly significant after adjusting for proportions of ancestry estimated using 30 unlinked microsatellites (adjusted odds ratio: 1.76 [95% confidence interval, CI: 1.17,2.65], p = 0.005). Since all common HapMap polymorphisms in ,500,kb contiguous regions have low-to-moderate linkage disequilibrium with Pro147Ser, we speculate that this polymorphism is causally related to the severe asthma phenotype in African Americans. The association of this polymorphism, located in the N-terminal region of the non-muscle MLCK isoform, emphasizes the potential importance of the vascular endothelium, a tissue in which MLCK is centrally involved in multiple aspects of the inflammatory response, in the pathogenesis of severe asthma. This finding also offers a possible genetic explanation for some of the more severe asthma phenotype observed in African American asthmatics. Genet Epidemiol 2007. © 2007 Wiley-Liss, Inc. [source]

    Faster returns on ,leaf economics' and different biogeochemical niche in invasive compared with native plant species

    Abstract Plant-invasive success is one of the most important current global changes in the biosphere. To understand which factors explain such success, we compared the foliar traits of 41 native and 47 alien-invasive plant species in Oahu Island (Hawaii), a location with a highly endemic flora that has evolved in isolation and is currently vulnerable to invasions by exotic plant species. Foliar traits, which in most cases presented significant phylogenetic signal, i.e. closely related species tended to resemble each other due to shared ancestry, separated invasive from native species. Invasive species had lower leaf mass per area and enhanced capacities in terms of productivity (photosynthetic capacity) and nutrient capture both of macro- (N, P, K) and microelements (Fe, Ni, Cu and Zn). All these differences remain highly significant after removing the effects of phylogenetic history. Alien-invasive species did not show higher efficiency at using limiting nutrient resources, but they got faster leaf economics returns and occupied a different biogeochemical niche, which helps to explain the success of invasive plants and suggests that potential increases in soil nutrient availability might favor further invasive plant success. [source]

    Historical writing in twelfth- and thirteenth-century Scotland: the Dunfermline compilation

    HISTORICAL RESEARCH, Issue 220 2010
    Alice Taylor
    This article examines the first three items in a manuscript housed in the Royal Library in Madrid but written at the Benedictine abbey of Dunfermline in Fife, Scotland during the reign of James III (1460,88). It argues that the three items were originally put together during the reign of Alexander III (1249,86) and together formed a compilation which should be viewed as the earliest extant history of the twelfth- and thirteenth-century kings of Scots. Interestingly, the Dunfermline compilation did not stress the Irish ancestry of the kings of Scots, as might be assumed, but instead set its subjects against the backdrop of their Anglo-Saxon descent from the house of Cerdic. The article then considers the relationship of the Dunfermline compilation to Turgot's Vita Sancte Margarete and Aelred of Rievaulx's Genealogia Regum Anglorum and argues that the use of these sources in the compilation suggest that it was put together for a particular political purpose, a purpose for which the Anglo-Saxon ancestry of the kings of Scots had particular relevance. [source]

    "The Pacific Era Has Arrived": Transnational Education among Japanese Americans, 1932,1941

    Eiichiro Azuma
    Looking back on the two years at Keisen Girls'School, I am so grateful for the opportunity to have been able to study here, Our teachers have taught us that it was mistaken if we simply aspired to mimic the ways ofJapanese woman. Cognizant of our special position as Americans of Japanese ancestry, we must instead strive to promote the U.S.-Japan friendship. Furthermore, we must adapt the merits of the Japanese spirit [that we have acquired here] to our Americanism. Back in the United States, we will dedicate ourselves to the good of our own society as best possible citizens, cooperating with Americans of other races and learning from each other, Such is the mission of the Nisei as a bridge between Japan and the United States,one that we have come to appreciate [through our schooling in Japan].1 [source]

    IBDfinder and SNPsetter: Tools for pedigree-independent identification of autozygous regions in individuals with recessive inherited disease,

    HUMAN MUTATION, Issue 6 2009
    Ian M. Carr
    Abstract Autozygosity mapping of recessive genes can be performed on a small number of affected individuals from consanguineous pedigrees. With the advent of microarray SNP analysis, acquiring genotype data has become extremely simple and quick, in comparison to gene mapping with microsatellite markers. However, the subsequent data analysis required to identify autozygous regions can still be a significant obstacle. For rapid gene identification, it may be desirable to integrate information from heterogeneous groups of affected individuals, both familial and isolated, under various assumptions of ancestry and locus heterogeneity, that are not amenable to formal linkage analysis. Unfortunately, there are few computer programs aimed specifically at facilitating this type of data sifting. Here, we demonstrate two new programs that facilitate the identification of autozygous regions within a heterogeneous SNP dataset derived from familial and sporadic affected individuals. Hum Mutat 30:1,8, 2009. © 2009 Wiley-Liss, Inc. [source]

    A panel of ancestry informative markers for estimating individual biogeographical ancestry and admixture from four continents: utility and applications,

    HUMAN MUTATION, Issue 5 2008
    Indrani Halder
    Abstract Autosomal ancestry informative markers (AIMs) are useful for inferring individual biogeographical ancestry (I-BGA) and admixture. Ancestry estimates obtained from Y and mtDNA are useful for reconstructing population expansions and migrations in our recent past but individual genomic admixture estimates are useful to test for association of admixture with phenotypes, as covariate in association studies to control for stratification and, in forensics, to estimate certain overt phenotypes from ancestry. We have developed a panel of 176 autosomal AIMs that can effectively distinguish I-BGA and admixture proportions from four continental ancestral populations: Europeans, West Africans, Indigenous Americans, and East Asians. We present allele frequencies for these AIMs in all four ancestral populations and use them to assess the global apportionment of I-BGA and admixture diversity among some extant populations. We observed patterns of apportionment similar to those described previously using sex and autosomal markers, such as European admixture for African Americans (14.3%) and Mexicans (43.2%), European (65.5%) and East Asian affiliation (27%) for South Asians, and low levels of African admixture (2.8,10.8%) mirroring the distribution of Y E3b haplogroups among various Eurasian populations. Using simulation studies and pedigree analysis we show that I-BGA estimates obtained using this panel and a four-population model has a high degree of precision (average root mean square error [RMSE]=0.026). Using ancestry,phenotype associations we demonstrate that a large and informative AIM panel such as this can help reduce false-positive and false-negative associations between phenotypes and admixture proportions, which may result when using a smaller panel of less informative AIMs. Hum Mutat 29(5), 648,658, 2008. © 2008 Wiley-Liss, Inc. [source]

    MHC microsatellites in a Southern Brazilian population

    C. Sens-Abuázar
    Summary Microsatellites are short tandem repeats of 1,6 bp DNA fragments, which are found throughout the genome. Due to their high levels of polymorphism, many of them are used as markers for population studies. Here we report an investigation on four microsatellites (D6S273, D6S2792, STR_MICA and D6S2810) located within the major histocompatibility complex in a sample of 281 Southern Brazilians of European ancestry. Allelic and haplotypic frequencies are described, as well as linkage disequilibrium (LD) between alleles of these microsatellites and alleles of three HLA genes: HLA-B, HLA-DRB1 and HLA-DQB1. The most polymorphic microsatellite was D6S2810, located close to the HLA-B locus. Strong LD was observed between alleles of microsatellites and HLA genes. The strongest associations occurred among STR_MICA*A5.1,HLA-B*13, STR_MICA*A6,HLA-B*49, STR_MICA*A9,HLA-B*39, STR_MICA*A9,HLAB*57, D6S2810*334,HLA-B*14, D6S2810*334,HLA-B*38, STR_MICA*A5.1,HLA-DRB1*1501,HLA-DQB1*0602 and D6S2810*344,HLA-DRB1*0411,HLA-DQB1*0302. This study contributes with important information on HLA haplotypes, and is potentially useful in resolving cases of low resolution HLA genotyping ambiguities. [source]