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Sample records for joint demographic history

  1. Inferring the Joint Demographic History of Multiple Populations from Multidimensional SNP Frequency Data

    PubMed Central

    Gutenkunst, Ryan N.; Hernandez, Ryan D.; Williamson, Scott H.; Bustamante, Carlos D.

    2009-01-01

    Demographic models built from genetic data play important roles in illuminating prehistorical events and serving as null models in genome scans for selection. We introduce an inference method based on the joint frequency spectrum of genetic variants within and between populations. For candidate models we numerically compute the expected spectrum using a diffusion approximation to the one-locus, two-allele Wright-Fisher process, involving up to three simultaneous populations. Our approach is a composite likelihood scheme, since linkage between neutral loci alters the variance but not the expectation of the frequency spectrum. We thus use bootstraps incorporating linkage to estimate uncertainties for parameters and significance values for hypothesis tests. Our method can also incorporate selection on single sites, predicting the joint distribution of selected alleles among populations experiencing a bevy of evolutionary forces, including expansions, contractions, migrations, and admixture. We model human expansion out of Africa and the settlement of the New World, using 5 Mb of noncoding DNA resequenced in 68 individuals from 4 populations (YRI, CHB, CEU, and MXL) by the Environmental Genome Project. We infer divergence between West African and Eurasian populations 140 thousand years ago (95% confidence interval: 40–270 kya). This is earlier than other genetic studies, in part because we incorporate migration. We estimate the European (CEU) and East Asian (CHB) divergence time to be 23 kya (95% c.i.: 17–43 kya), long after archeological evidence places modern humans in Europe. Finally, we estimate divergence between East Asians (CHB) and Mexican-Americans (MXL) of 22 kya (95% c.i.: 16.3–26.9 kya), and our analysis yields no evidence for subsequent migration. Furthermore, combining our demographic model with a previously estimated distribution of selective effects among newly arising amino acid mutations accurately predicts the frequency spectrum of

  2. Geographical barriers and climate influence demographic history in narrowleaf cottonwoods

    PubMed Central

    Evans, L M; Allan, G J; DiFazio, S P; Slavov, G T; Wilder, J A; Floate, K D; Rood, S B; Whitham, T G

    2015-01-01

    Studies of genetic variation can clarify the role of geography and spatio-temporal variation of climate in shaping demography, particularly in temperate zone tree species with large latitudinal ranges. Here, we examined genetic variation in narrowleaf cottonwood, Populus angustifolia, a dominant riparian tree. Using multi-locus surveys of polymorphism in 363 individuals across the species' 1800 km latitudinal range, we found that, first, P. angustifolia has stronger neutral genetic structure than many forest trees (simple sequence repeat (SSR) FST=0.21), with major genetic groups corresponding to large apparent geographical barriers to gene flow. Second, using SSRs and putatively neutral sequenced loci, coalescent simulations indicated that populations diverged before the last glacial maximum (LGM), suggesting the presence of population structure before the LGM. Third, the LGM and subsequent warming appear to have had different influences on each of these distinct populations, with effective population size reduction in the southern extent of the range but major expansion in the north. These results are consistent with the hypothesis that climate and geographic barriers have jointly affected the demographic history of P. angustifolia, and point the importance of both factors as being instrumental in shaping genetic variation and structure in widespread forest trees. PMID:25585921

  3. Linkage Disequilibrium and Demographic History of Wild and Domestic Canids

    PubMed Central

    Gray, Melissa M.; Granka, Julie M.; Bustamante, Carlos D.; Sutter, Nathan B.; Boyko, Adam R.; Zhu, Lan; Ostrander, Elaine A.; Wayne, Robert K.

    2009-01-01

    Assessing the extent of linkage disequilibrium (LD) in natural populations of a nonmodel species has been difficult due to the lack of available genomic markers. However, with advances in genotyping and genome sequencing, genomic characterization of natural populations has become feasible. Using sequence data and SNP genotypes, we measured LD and modeled the demographic history of wild canid populations and domestic dog breeds. In 11 gray wolf populations and one coyote population, we find that the extent of LD as measured by the distance at which r2 = 0.2 extends <10 kb in outbred populations to >1.7 Mb in populations that have experienced significant founder events and bottlenecks. This large range in the extent of LD parallels that observed in 18 dog breeds where the r2 value varies from ∼20 kb to >5 Mb. Furthermore, in modeling demographic history under a composite-likelihood framework, we find that two of five wild canid populations exhibit evidence of a historical population contraction. Five domestic dog breeds display evidence for a minor population contraction during domestication and a more severe contraction during breed formation. Only a 5% reduction in nucleotide diversity was observed as a result of domestication, whereas the loss of nucleotide diversity with breed formation averaged 35%. PMID:19189949

  4. Genealogy and Demographic History of a Widespread Amphibian throughout Indochina.

    PubMed

    Blair, Christopher; Davy, Christina M; Ngo, Andre; Orlov, Nikolai L; Shi, Hai-tao; Lu, Shun-qing; Gao, Lan; Rao, Ding-qi; Murphy, Robert W

    2013-01-01

    Relatively little is known about spatial patterns of cryptic diversity in tropical species and the processes that generate them. Few studies examine the geographic distribution of genetic lineages in Southeast Asia, an area hypothesized to harbor substantial cryptic diversity. We investigated the evolutionary history of Asian tree frogs of the Polypedates leucomystax complex (n = 172) based on 1800 bp of the mtDNA genes ND1 and cytochrome b and tested hypotheses pertaining to climate, geology, and dispersal patterns. Analyses revealed substantial genetic diversity and lineage divergence throughout the region with evidence for widespread sympatric lineages and a general north versus south clustering. Relaxed molecular clock analysis and tests for demographic expansion identified an initial cladogenesis during the Miocene with subsequent Plio-Pleistocene diversification, with the former corresponding to periods of increased aridity and the onset of monsoonal weather systems. Rates of diversification were relatively constant until the Early Pleistocene when rates increased exponentially. We found equivocal evidence for isolation-by-distance and a potential role of some landscape features as partial barriers to dispersal. Finally, our analyses showed that divergence between insular and mainland populations occurred before Homo sapiens colonized Southeast Asia, suggesting that historical human-mediated dispersal did not drive insular diversification. Our results suggested that demographic expansion in the Late Pleistocene resulted in widespread sympatric lineages in the P. leucomystax complex throughout southern China and Indochina and further clarified the evolutionary history of lineages within P. leucomystax.

  5. Contrasting demographic histories of the neighboring bonobo and chimpanzee.

    PubMed

    Hvilsom, Christina; Carlsen, Frands; Heller, Rasmus; Jaffré, Nina; Siegismund, Hans R

    2014-01-01

    The Pleistocene epoch was a period of dramatic climate change that had profound impacts on the population sizes of many animal species. How these species were shaped by past events is often unclear, hindering our understanding of the population dynamics resulting in present day populations. We analyzed complete mitochondrial genomes representing all four recognized chimpanzee subspecies and the bonobo to infer the recent demographic history and used simulations to exclude a confounding effect of population structure. Our genus-wide Bayesian coalescent-based analysis revealed surprisingly dissimilar demographic histories of the chimpanzee subspecies and the bonobo, despite their overlapping habitat requirements. Whereas the central and eastern chimpanzee subspecies were inferred to have expanded tenfold between around 50,000 and 80,000 years ago and today, the population size of the neighboring bonobo remained constant. The changes in population size are likely linked to changes in habitat area due to climate oscillations during the late Pleistocene. Furthermore, the timing of population expansion for the rainforest-adapted chimpanzee is concurrent with the expansion of the savanna-adapted human, which could suggest a common response to changed climate conditions around 50,000-80,000 years ago.

  6. Demographic history of India and mtDNA-sequence diversity.

    PubMed Central

    Mountain, J L; Hebert, J M; Bhattacharyya, S; Underhill, P A; Ottolenghi, C; Gadgil, M; Cavalli-Sforza, L L

    1995-01-01

    The demographic history of India was examined by comparing mtDNA sequences obtained from members of three culturally divergent Indian subpopulations (endogamous caste groups). While an inferred tree revealed some clustering according to caste affiliation, there was no clear separation into three genetically distinct groups along caste lines. Comparison of pairwise nucleotide difference distributions, however, did indicate a difference in growth patterns between two of the castes. The Brahmin population appears to have undergone either a rapid expansion or steady growth. The low-ranking Mukri caste, however, may have either maintained a roughly constant population size or undergone multiple bottlenecks during that period. Comparison of the Indian sequences to those obtained from other populations, using a tree, revealed that the Indian sequences, along with all other non-African samples, form a starlike cluster. This cluster may represent a major expansion, possibly originating in southern Asia, taking place at some point after modern humans initially left Africa. PMID:7717409

  7. Demographic history and linkage disequilibrium in human populations.

    PubMed

    Laan, M; Pääbo, S

    1997-12-01

    In the human genome, linkage disequilibrium (LD)--the non-random association of alleles at chromosomal loci--has been studied mainly in regions surrounding disease genes on affected chromosomes. Consequently, little information is available on the distribution of LD across anonymous genomic regions in the general population. However, demographic history is expected to influence the extent of overall LD across the genome, so a population that has been of constant size will display higher levels of LD than a population that has expanded. In support of this, the extent of LD between anonymous loci on chromosome 4 in chimpanzees (as a model of a population of constant size) has been compared to that in Finns (as a model of an expanded population; refs 8,9) and found to exhibit more LD than in the latter population. In Europe, studies of mitochondrial (mt) DNA sequences have suggested that most populations have experienced expansion, whereas the Saami in northern Fenno-Scandinavia have been of constant size (Table 1). Thus, in northern Europe, populations with radically different demographic histories live in close geographic proximity to each other. We studied the allelic associations between anonymous microsatellite loci on the X chromosome in the Saami and neighbouring populations and found dramatically higher levels of LD in the Saami than in other populations in the region. This indicates that whereas recently expanded populations, such as the Finns, are well suited to map single disease genes affected by recent mutations, populations that have been of constant size, such as the Saami, may be much better suited to map genes for complex traits that are caused by older mutations.

  8. Selection, recombination and demographic history in Drosophila miranda.

    PubMed

    Bachtrog, Doris; Andolfatto, Peter

    2006-12-01

    Selection, recombination, and the demographic history of a species can all have profound effects on genomewide patterns of variability. To assess the impact of these forces in the genome of Drosophila miranda, we examine polymorphism and divergence patterns at 62 loci scattered across the genome. In accordance with recent findings in D. melanogaster, we find that noncoding DNA generally evolves more slowly than synonymous sites, that the distribution of polymorphism frequencies in noncoding DNA is significantly skewed toward rare variants relative to synonymous sites, and that long introns evolve significantly slower than short introns or synonymous sites. These observations suggest that most noncoding DNA is functionally constrained and evolving under purifying selection. However, in contrast to findings in the D. melanogaster species group, we find little evidence of adaptive evolution acting on either coding or noncoding sequences in D. miranda. Levels of linkage disequilibrium (LD) in D. miranda are comparable to those observed in D. melanogaster, but vary considerably among chromosomes. These patterns suggest a significantly lower rate of recombination on autosomes, possibly due to the presence of polymorphic autosomal inversions and/or differences in chromosome sizes. All chromosomes show significant departures from the standard neutral model, including too much heterogeneity in synonymous site polymorphism relative to divergence among loci and a general excess of rare synonymous polymorphisms. These departures from neutral equilibrium expectations are discussed in the context of nonequilibrium models of demography and selection.

  9. Demographic history and rare allele sharing among human populations.

    PubMed

    Gravel, Simon; Henn, Brenna M; Gutenkunst, Ryan N; Indap, Amit R; Marth, Gabor T; Clark, Andrew G; Yu, Fuli; Gibbs, Richard A; Bustamante, Carlos D

    2011-07-19

    High-throughput sequencing technology enables population-level surveys of human genomic variation. Here, we examine the joint allele frequency distributions across continental human populations and present an approach for combining complementary aspects of whole-genome, low-coverage data and targeted high-coverage data. We apply this approach to data generated by the pilot phase of the Thousand Genomes Project, including whole-genome 2-4× coverage data for 179 samples from HapMap European, Asian, and African panels as well as high-coverage target sequencing of the exons of 800 genes from 697 individuals in seven populations. We use the site frequency spectra obtained from these data to infer demographic parameters for an Out-of-Africa model for populations of African, European, and Asian descent and to predict, by a jackknife-based approach, the amount of genetic diversity that will be discovered as sample sizes are increased. We predict that the number of discovered nonsynonymous coding variants will reach 100,000 in each population after ∼1,000 sequenced chromosomes per population, whereas ∼2,500 chromosomes will be needed for the same number of synonymous variants. Beyond this point, the number of segregating sites in the European and Asian panel populations is expected to overcome that of the African panel because of faster recent population growth. Overall, we find that the majority of human genomic variable sites are rare and exhibit little sharing among diverged populations. Our results emphasize that replication of disease association for specific rare genetic variants across diverged populations must overcome both reduced statistical power because of rarity and higher population divergence.

  10. Demographic history and rare allele sharing among human populations

    PubMed Central

    Gravel, Simon; Henn, Brenna M.; Gutenkunst, Ryan N.; Indap, Amit R.; Marth, Gabor T.; Clark, Andrew G.; Yu, Fuli; Gibbs, Richard A.; Bustamante, Carlos D.; Altshuler, David L.; Durbin, Richard M.; Abecasis, Gonçalo R.; Bentley, David R.; Chakravarti, Aravinda; Clark, Andrew G.; Collins, Francis S.; De La Vega, Francisco M.; Donnelly, Peter; Egholm, Michael; Flicek, Paul; Gabriel, Stacey B.; Gibbs, Richard A.; Knoppers, Bartha M.; Lander, Eric S.; Lehrach, Hans; Mardis, Elaine R.; McVean, Gil A.; Nickerson, Debbie A.; Peltonen, Leena; Schafer, Alan J.; Sherry, Stephen T.; Wang, Jun; Wilson, Richard K.; Gibbs, Richard A.; Deiros, David; Metzker, Mike; Muzny, Donna; Reid, Jeff; Wheeler, David; Wang, Jun; Li, Jingxiang; Jian, Min; Li, Guoqing; Li, Ruiqiang; Liang, Huiqing; Tian, Geng; Wang, Bo; Wang, Jian; Wang, Wei; Yang, Huanming; Zhang, Xiuqing; Zheng, Huisong; Lander, Eric S.; Altshuler, David L.; Ambrogio, Lauren; Bloom, Toby; Cibulskis, Kristian; Fennell, Tim J.; Gabriel, Stacey B.; Jaffe, David B.; Shefler, Erica; Sougnez, Carrie L.; Bentley, David R.; Gormley, Niall; Humphray, Sean; Kingsbury, Zoya; Koko-Gonzales, Paula; Stone, Jennifer; McKernan, Kevin J.; Costa, Gina L.; Ichikawa, Jeffry K.; Lee, Clarence C.; Sudbrak, Ralf; Lehrach, Hans; Borodina, Tatiana A.; Dahl, Andreas; Davydov, Alexey N.; Marquardt, Peter; Mertes, Florian; Nietfeld, Wilfiried; Rosenstiel, Philip; Schreiber, Stefan; Soldatov, Aleksey V.; Timmermann, Bernd; Tolzmann, Marius; Egholm, Michael; Affourtit, Jason; Ashworth, Dana; Attiya, Said; Bachorski, Melissa; Buglione, Eli; Burke, Adam; Caprio, Amanda; Celone, Christopher; Clark, Shauna; Conners, David; Desany, Brian; Gu, Lisa; Guccione, Lorri; Kao, Kalvin; Kebbel, Andrew; Knowlton, Jennifer; Labrecque, Matthew; McDade, Louise; Mealmaker, Craig; Minderman, Melissa; Nawrocki, Anne; Niazi, Faheem; Pareja, Kristen; Ramenani, Ravi; Riches, David; Song, Wanmin; Turcotte, Cynthia; Wang, Shally; Mardis, Elaine R.; Wilson, Richard K.; Dooling, David; Fulton, Lucinda; Fulton, Robert; Weinstock, George; Durbin, Richard M.; Burton, John; Carter, David M.; Churcher, Carol; Coffey, Alison; Cox, Anthony; Palotie, Aarno; Quail, Michael; Skelly, Tom; Stalker, James; Swerdlow, Harold P.; Turner, Daniel; De Witte, Anniek; Giles, Shane; Gibbs, Richard A.; Wheeler, David; Bainbridge, Matthew; Challis, Danny; Sabo, Aniko; Yu, Fuli; Yu, Jin; Wang, Jun; Fang, Xiaodong; Guo, Xiaosen; Li, Ruiqiang; Li, Yingrui; Luo, Ruibang; Tai, Shuaishuai; Wu, Honglong; Zheng, Hancheng; Zheng, Xiaole; Zhou, Yan; Li, Guoqing; Wang, Jian; Yang, Huanming; Marth, Gabor T.; Garrison, Erik P.; Huang, Weichun; Indap, Amit; Kural, Deniz; Lee, Wan-Ping; Leong, Wen Fung; Quinlan, Aaron R.; Stewart, Chip; Stromberg, Michael P.; Ward, Alistair N.; Wu, Jiantao; Lee, Charles; Mills, Ryan E.; Shi, Xinghua; Daly, Mark J.; DePristo, Mark A.; Altshuler, David L.; Ball, Aaron D.; Banks, Eric; Bloom, Toby; Browning, Brian L.; Cibulskis, Kristian; Fennell, Tim J.; Garimella, Kiran V.; Grossman, Sharon R.; Handsaker, Robert E.; Hanna, Matt; Hartl, Chris; Jaffe, David B.; Kernytsky, Andrew M.; Korn, Joshua M.; Li, Heng; Maguire, Jared R.; McCarroll, Steven A.; McKenna, Aaron; Nemesh, James C.; Philippakis, Anthony A.; Poplin, Ryan E.; Price, Alkes; Rivas, Manuel A.; Sabeti, Pardis C.; Schaffner, Stephen F.; Shefler, Erica; Shlyakhter, Ilya A.; Cooper, David N.; Ball, Edward V.; Mort, Matthew; Phillips, Andrew D.; Stenson, Peter D.; Sebat, Jonathan; Makarov, Vladimir; Ye, Kenny; Yoon, Seungtai C.; Bustamante, Carlos D.; Clark, Andrew G.; Boyko, Adam; Degenhardt, Jeremiah; Gravel, Simon; Gutenkunst, Ryan N.; Kaganovich, Mark; Keinan, Alon; Lacroute, Phil; Ma, Xin; Reynolds, Andy; Clarke, Laura; Flicek, Paul; Cunningham, Fiona; Herrero, Javier; Keenen, Stephen; Kulesha, Eugene; Leinonen, Rasko; McLaren, William M.; Radhakrishnan, Rajesh; Smith, Richard E.; Zalunin, Vadim; Zheng-Bradley, Xiangqun; Korbel, Jan O.; Stütz, Adrian M.; Humphray, Sean; Bauer, Markus; Cheetham, R. Keira; Cox, Tony; Eberle, Michael; James, Terena; Kahn, Scott; Murray, Lisa; Chakravarti, Aravinda; Ye, Kai; De La Vega, Francisco M.; Fu, Yutao; Hyland, Fiona C. L.; Manning, Jonathan M.; McLaughlin, Stephen F.; Peckham, Heather E.; Sakarya, Onur; Sun, Yongming A.; Tsung, Eric F.; Batzer, Mark A.; Konkel, Miriam K.; Walker, Jerilyn A.; Sudbrak, Ralf; Albrecht, Marcus W.; Amstislavskiy, Vyacheslav S.; Herwig, Ralf; Parkhomchuk, Dimitri V.; Sherry, Stephen T.; Agarwala, Richa; Khouri, Hoda M.; Morgulis, Aleksandr O.; Paschall, Justin E.; Phan, Lon D.; Rotmistrovsky, Kirill E.; Sanders, Robert D.; Shumway, Martin F.; Xiao, Chunlin; McVean, Gil A.; Auton, Adam; Iqbal, Zamin; Lunter, Gerton; Marchini, Jonathan L.; Moutsianas, Loukas; Myers, Simon; Tumian, Afidalina; Desany, Brian; Knight, James; Winer, Roger; Craig, David W.; Beckstrom-Sternberg, Steve M.; Christoforides, Alexis; Kurdoglu, Ahmet A.; Pearson, John V.; Sinari, Shripad A.; Tembe, Waibhav D.; Haussler, David; Hinrichs, Angie S.; Katzman, Sol J.; Kern, Andrew; Kuhn, Robert M.; Przeworski, Molly; Hernandez, Ryan D.; Howie, Bryan; Kelley, Joanna L.; Melton, S. Cord; Abecasis, Gonçalo R.; Li, Yun; Anderson, Paul; Blackwell, Tom; Chen, Wei; Cookson, William O.; Ding, Jun; Kang, Hyun Min; Lathrop, Mark; Liang, Liming; Moffatt, Miriam F.; Scheet, Paul; Sidore, Carlo; Snyder, Matthew; Zhan, Xiaowei; Zöllner, Sebastian; Awadalla, Philip; Casals, Ferran; Idaghdour, Youssef; Keebler, John; Stone, Eric A.; Zilversmit, Martine; Jorde, Lynn; Xing, Jinchuan; Eichler, Evan E.; Aksay, Gozde; Alkan, Can; Hajirasouliha, Iman; Hormozdiari, Fereydoun; Kidd, Jeffrey M.; Sahinalp, S. Cenk; Sudmant, Peter H.; Mardis, Elaine R.; Chen, Ken; Chinwalla, Asif; Ding, Li; Koboldt, Daniel C.; McLellan, Mike D.; Dooling, David; Weinstock, George; Wallis, John W.; Wendl, Michael C.; Zhang, Qunyuan; Durbin, Richard M.; Albers, Cornelis A.; Ayub, Qasim; Balasubramaniam, Senduran; Barrett, Jeffrey C.; Carter, David M.; Chen, Yuan; Conrad, Donald F.; Danecek, Petr; Dermitzakis, Emmanouil T.; Hu, Min; Huang, Ni; Hurles, Matt E.; Jin, Hanjun; Jostins, Luke; Keane, Thomas M.; Le, Si Quang; Lindsay, Sarah; Long, Quan; MacArthur, Daniel G.; Montgomery, Stephen B.; Parts, Leopold; Stalker, James; Tyler-Smith, Chris; Walter, Klaudia; Zhang, Yujun; Gerstein, Mark B.; Snyder, Michael; Abyzov, Alexej; Balasubramanian, Suganthi; Bjornson, Robert; Du, Jiang; Grubert, Fabian; Habegger, Lukas; Haraksingh, Rajini; Jee, Justin; Khurana, Ekta; Lam, Hugo Y. K.; Leng, Jing; Mu, Xinmeng Jasmine; Urban, Alexander E.; Zhang, Zhengdong; Li, Yingrui; Luo, Ruibang; Marth, Gabor T.; Garrison, Erik P.; Kural, Deniz; Quinlan, Aaron R.; Stewart, Chip; Stromberg, Michael P.; Ward, Alistair N.; Wu, Jiantao; Lee, Charles; Mills, Ryan E.; Shi, Xinghua; McCarroll, Steven A.; Banks, Eric; DePristo, Mark A.; Handsaker, Robert E.; Hartl, Chris; Korn, Joshua M.; Li, Heng; Nemesh, James C.; Sebat, Jonathan; Makarov, Vladimir; Ye, Kenny; Yoon, Seungtai C.; Degenhardt, Jeremiah; Kaganovich, Mark; Clarke, Laura; Smith, Richard E.; Zheng-Bradley, Xiangqun; Korbel, Jan O.; Humphray, Sean; Cheetham, R. Keira; Eberle, Michael; Kahn, Scott; Murray, Lisa; Ye, Kai; De La Vega, Francisco M.; Fu, Yutao; Peckham, Heather E.; Sun, Yongming A.; Batzer, Mark A.; Konkel, Miriam K.; Walker, Jerilyn A.; Xiao, Chunlin; Iqbal, Zamin; Desany, Brian; Blackwell, Tom; Snyder, Matthew; Xing, Jinchuan; Eichler, Evan E.; Aksay, Gozde; Alkan, Can; Hajirasouliha, Iman; Hormozdiari, Fereydoun; Kidd, Jeffrey M.; Chen, Ken; Chinwalla, Asif; Ding, Li; McLellan, Mike D.; Wallis, John W.; Hurles, Matt E.; Conrad, Donald F.; Walter, Klaudia; Zhang, Yujun; Gerstein, Mark B.; Snyder, Michael; Abyzov, Alexej; Du, Jiang; Grubert, Fabian; Haraksingh, Rajini; Jee, Justin; Khurana, Ekta; Lam, Hugo Y. K.; Leng, Jing; Mu, Xinmeng Jasmine; Urban, Alexander E.; Zhang, Zhengdong; Gibbs, Richard A.; Bainbridge, Matthew; Challis, Danny; Coafra, Cristian; Dinh, Huyen; Kovar, Christie; Lee, Sandy; Muzny, Donna; Nazareth, Lynne; Reid, Jeff; Sabo, Aniko; Yu, Fuli; Yu, Jin; Marth, Gabor T.; Garrison, Erik P.; Indap, Amit; Leong, Wen Fung; Quinlan, Aaron R.; Stewart, Chip; Ward, Alistair N.; Wu, Jiantao; Cibulskis, Kristian; Fennell, Tim J.; Gabriel, Stacey B.; Garimella, Kiran V.; Hartl, Chris; Shefler, Erica; Sougnez, Carrie L.; Wilkinson, Jane; Clark, Andrew G.; Gravel, Simon; Grubert, Fabian; Clarke, Laura; Flicek, Paul; Smith, Richard E.; Zheng-Bradley, Xiangqun; Sherry, Stephen T.; Khouri, Hoda M.; Paschall, Justin E.; Shumway, Martin F.; Xiao, Chunlin; McVean, Gil A.; Katzman, Sol J.; Abecasis, Gonçalo R.; Blackwell, Tom; Mardis, Elaine R.; Dooling, David; Fulton, Lucinda; Fulton, Robert; Koboldt, Daniel C.; Durbin, Richard M.; Balasubramaniam, Senduran; Coffey, Allison; Keane, Thomas M.; MacArthur, Daniel G.; Palotie, Aarno; Scott, Carol; Stalker, James; Tyler-Smith, Chris; Gerstein, Mark B.; Balasubramanian, Suganthi; Chakravarti, Aravinda; Knoppers, Bartha M.; Abecasis, Gonçalo R.; Bustamante, Carlos D.; Gharani, Neda; Gibbs, Richard A.; Jorde, Lynn; Kaye, Jane S.; Kent, Alastair; Li, Taosha; McGuire, Amy L.; McVean, Gil A.; Ossorio, Pilar N.; Rotimi, Charles N.; Su, Yeyang; Toji, Lorraine H.; TylerSmith, Chris; Brooks, Lisa D.; Felsenfeld, Adam L.; McEwen, Jean E.; Abdallah, Assya; Juenger, Christopher R.; Clemm, Nicholas C.; Collins, Francis S.; Duncanson, Audrey; Green, Eric D.; Guyer, Mark S.; Peterson, Jane L.; Schafer, Alan J.; Abecasis, Gonçalo R.; Altshuler, David L.; Auton, Adam; Brooks, Lisa D.; Durbin, Richard M.; Gibbs, Richard A.; Hurles, Matt E.; McVean, Gil A.

    2011-01-01

    High-throughput sequencing technology enables population-level surveys of human genomic variation. Here, we examine the joint allele frequency distributions across continental human populations and present an approach for combining complementary aspects of whole-genome, low-coverage data and targeted high-coverage data. We apply this approach to data generated by the pilot phase of the Thousand Genomes Project, including whole-genome 2–4× coverage data for 179 samples from HapMap European, Asian, and African panels as well as high-coverage target sequencing of the exons of 800 genes from 697 individuals in seven populations. We use the site frequency spectra obtained from these data to infer demographic parameters for an Out-of-Africa model for populations of African, European, and Asian descent and to predict, by a jackknife-based approach, the amount of genetic diversity that will be discovered as sample sizes are increased. We predict that the number of discovered nonsynonymous coding variants will reach 100,000 in each population after ∼1,000 sequenced chromosomes per population, whereas ∼2,500 chromosomes will be needed for the same number of synonymous variants. Beyond this point, the number of segregating sites in the European and Asian panel populations is expected to overcome that of the African panel because of faster recent population growth. Overall, we find that the majority of human genomic variable sites are rare and exhibit little sharing among diverged populations. Our results emphasize that replication of disease association for specific rare genetic variants across diverged populations must overcome both reduced statistical power because of rarity and higher population divergence. PMID:21730125

  11. Inferring Demographic History from a Spectrum of Shared Haplotype Lengths

    PubMed Central

    Harris, Kelley; Nielsen, Rasmus

    2013-01-01

    There has been much recent excitement about the use of genetics to elucidate ancestral history and demography. Whole genome data from humans and other species are revealing complex stories of divergence and admixture that were left undiscovered by previous smaller data sets. A central challenge is to estimate the timing of past admixture and divergence events, for example the time at which Neanderthals exchanged genetic material with humans and the time at which modern humans left Africa. Here, we present a method for using sequence data to jointly estimate the timing and magnitude of past admixture events, along with population divergence times and changes in effective population size. We infer demography from a collection of pairwise sequence alignments by summarizing their length distribution of tracts of identity by state (IBS) and maximizing an analytic composite likelihood derived from a Markovian coalescent approximation. Recent gene flow between populations leaves behind long tracts of identity by descent (IBD), and these tracts give our method power by influencing the distribution of shared IBS tracts. In simulated data, we accurately infer the timing and strength of admixture events, population size changes, and divergence times over a variety of ancient and recent time scales. Using the same technique, we analyze deeply sequenced trio parents from the 1000 Genomes project. The data show evidence of extensive gene flow between Africa and Europe after the time of divergence as well as substructure and gene flow among ancestral hominids. In particular, we infer that recent African-European gene flow and ancient ghost admixture into Europe are both necessary to explain the spectrum of IBS sharing in the trios, rejecting simpler models that contain less population structure. PMID:23754952

  12. Linkage disequilibrium reveals different demographic history in egg laying chickens

    PubMed Central

    2010-01-01

    Background The availability of larger-scale SNP data sets in the chicken genome allows to achieve a higher resolution of the pattern of linkage disequilibrium (LD). In this study, 36 k and 57 k genotypes from two independent genotyping chips were used to systematically characterize genome-wide extent and structure of LD in the genome of four chicken populations. In total, we analyzed genotypes of 454 animals from two commercial and two experimental populations of white and brown layers which allows to some extent a generalization of the results. Results The number of usable SNPs in this study was 19 k to 37 k in brown layers and 8 k to 19 k in white layers. Our analyzes showed a large difference of LD between the lines of white and brown layers. A mean value of r2 = 0.73 ± 0.36 was observed in pair-wise distances of < 25 Kb for commercial white layers, and it dropped to 0.60 ± 0.38 with distances of 75 to 120 Kb, the interval which includes the average inter-marker space in this line. In contrast, an overall mean value of r2= 0.32 ± 0.33 was observed for SNPs less than 25 Kb apart from each other and dropped to 0.21 ± 0.26 at a distance of 100 kb in commercial brown layers. There was a remarkable similarity of the LD patterns among the two populations of white layers. The same was true for the two populations of brown layers, while the LD pattern between white and brown layers was clearly different. Inferring the population demographic history from LD data resulted in a larger effective population size in brown than white populations, reflecting less inbreeding among brown compared to white egg layers. Conclusions We report comprehensive LD map statistics for the genome of egg laying chickens with an up to 3 times higher resolution compared to the maps available so far. The results were found to be consistent between analyzes based on the parallel SNP chips and across different populations (commercial vs. experimental) within the brown and the white layers. It

  13. [Hereditary spherocytosis: Review. Part I. History, demographics, pathogenesis, and diagnosis].

    PubMed

    Donato, Hugo; Crisp, Renée Leonor; Rapetti, María Cristina; García, Eliana; Attie, Myriam

    2015-01-01

    Hereditary spherocytosis is the most frequent hereditary anemia excluding beta thalassemia in Argentina. Historical, demographic, genetic and pathogenic aspects of the disease are reviewed, and confirmatory laboratory tests are described. Special characteristics on the outcome of the disease in our population and prevalent protein deficiencies in our country are described. Emphasis is given on new available laboratory tests, which allow an earlier diagnosis using volume of blood samples significantly smaller than required for conventional tests.

  14. Joint Genome Institute's Automation Approach and History

    SciTech Connect

    Roberts, Simon

    2006-07-05

    Department of Energy/Joint Genome Institute (DOE/JGI) collaborates with DOE national laboratories and community users, to advance genome science in support of the DOE missions of clean bio-energy, carbon cycling, and bioremediation.

  15. Demographic buffering of life histories? Implications of the choice of measurement scale.

    PubMed

    Bjørkvoll, Eirin; Lee, Aline M; Grøtan, Vidar; Saether, Bernt-Erikik; Stien, Audun; Engen, Steinar; Albon, Steve; Loe, Leif Egil; Hansen, Brage Bremset

    2016-01-01

    Life-history theory predicts that the vital rates that influence population growth the most should be buffered against environmental fluctuations due to selection for reduced variation. However, it remains unclear whether populations actually are influenced by such "demographic buffering," because variation in vital rates can be compared on different measurement scales, and there has been little attempt to investigate whether the choice of scale influences the chance of detecting demographic buffering. We compared two statistical approaches to examine whether demographic buffering has influenced vital rates in wild Svalbard reindeer (Rangifer tarandus platyrhynchus). To account for statistical variance constraints on vital rates limited between 0 and 1 in analyses of demographic buffering, one approach is to scale observed variation by the maximum possible variation on the arithmetic scale. When applying this approach, the results suggested that demographic buffering was occurring. However, when we applied an alternative approach that identified statistical variance constraints on the logit scale, there was no evidence for demographic buffering. Thus, the choice of measurement scale must be carefully considered before one can fully understand whether demographic buffering influences life histories. Defining the appropriate scale may require an understanding of the mechanisms through which demographic buffering may have evolved. PMID:27008773

  16. Formal linguistics as a cue to demographic history.

    PubMed

    Longobardi, Giuseppe; Ceolin, Andrea; Ecay, Aaron; Ghirotto, Silvia; Guardiano, Cristina; Irimia, Monica-Alexandrina; Michelioudakis, Dimitris; Radkevich, Nina; Pettener, Davide; Luiselli, Donata; Barbujani, Guido

    2016-06-20

    Beyond its theoretical success, the development of molecular genetics has brought about the possibility of extraordinary progress in the study of classification and in the inference of the evolutionary history of many species and populations. A major step forward was represented by the availability of extremely large sets of molecular data suited to quantitative and computational treatments. In this paper, we argue that even in cognitive sciences, purely theoretical progress in a discipline such as linguistics may have analogous impact. Thus, exactly on the model of molecular biology, we propose to unify two traditionally unrelated lines of linguistic investigation: 1) the formal study of syntactic variation (parameter theory) in the biolinguistic program; 2) the reconstruction of relatedness among languages (phylogenetic taxonomy). The results of our linguistic analysis have thus been plotted against data from population genetics and the correlations have turned out to be largely significant: given a non-trivial set of languages/populations, the description of their variation provided by the comparison of systematic parametric analysis and molecular anthropology informatively recapitulates their history and relationships. As a result, we can claim that the reality of some parametric model of the language faculty and language acquisition/transmission (more broadly of generative grammar) receives strong and original support from its historical heuristic power. Then, on these grounds, we can begin testing Darwin's prediction that, when properly generated, the trees of human populations and of their languages should eventually turn out to be significantly parallel. PMID:27081010

  17. Formal linguistics as a cue to demographic history.

    PubMed

    Longobardi, Giuseppe; Ceolin, Andrea; Ecay, Aaron; Ghirotto, Silvia; Guardiano, Cristina; Irimia, Monica-Alexandrina; Michelioudakis, Dimitris; Radkevich, Nina; Pettener, Davide; Luiselli, Donata; Barbujani, Guido

    2016-06-20

    Beyond its theoretical success, the development of molecular genetics has brought about the possibility of extraordinary progress in the study of classification and in the inference of the evolutionary history of many species and populations. A major step forward was represented by the availability of extremely large sets of molecular data suited to quantitative and computational treatments. In this paper, we argue that even in cognitive sciences, purely theoretical progress in a discipline such as linguistics may have analogous impact. Thus, exactly on the model of molecular biology, we propose to unify two traditionally unrelated lines of linguistic investigation: 1) the formal study of syntactic variation (parameter theory) in the biolinguistic program; 2) the reconstruction of relatedness among languages (phylogenetic taxonomy). The results of our linguistic analysis have thus been plotted against data from population genetics and the correlations have turned out to be largely significant: given a non-trivial set of languages/populations, the description of their variation provided by the comparison of systematic parametric analysis and molecular anthropology informatively recapitulates their history and relationships. As a result, we can claim that the reality of some parametric model of the language faculty and language acquisition/transmission (more broadly of generative grammar) receives strong and original support from its historical heuristic power. Then, on these grounds, we can begin testing Darwin's prediction that, when properly generated, the trees of human populations and of their languages should eventually turn out to be significantly parallel.

  18. Demographic histories, isolation and social factors as determinants of the genetic structure of Alpine linguistic groups.

    PubMed

    Coia, Valentina; Capocasa, Marco; Anagnostou, Paolo; Pascali, Vincenzo; Scarnicci, Francesca; Boschi, Ilaria; Battaggia, Cinzia; Crivellaro, Federica; Ferri, Gianmarco; Alù, Milena; Brisighelli, Francesca; Busby, George B J; Capelli, Cristian; Maixner, Frank; Cipollini, Giovanna; Viazzo, Pier Paolo; Zink, Albert; Destro Bisol, Giovanni

    2013-01-01

    Great European mountain ranges have acted as barriers to gene flow for resident populations since prehistory and have offered a place for the settlement of small, and sometimes culturally diverse, communities. Therefore, the human groups that have settled in these areas are worth exploring as an important potential source of diversity in the genetic structure of European populations. In this study, we present new high resolution data concerning Y chromosomal variation in three distinct Alpine ethno-linguistic groups, Italian, Ladin and German. Combining unpublished and literature data on Y chromosome and mitochondrial variation, we were able to detect different genetic patterns. In fact, within and among population diversity values observed vary across linguistic groups, with German and Italian speakers at the two extremes, and seem to reflect their different demographic histories. Using simulations we inferred that the joint effect of continued genetic isolation and reduced founding group size may explain the apportionment of genetic diversity observed in all groups. Extending the analysis to other continental populations, we observed that the genetic differentiation of Ladins and German speakers from Europeans is comparable or even greater to that observed for well known outliers like Sardinian and Basques. Finally, we found that in south Tyroleans, the social practice of Geschlossener Hof, a hereditary norm which might have favored male dispersal, coincides with a significant intra-group diversity for mtDNA but not for Y chromosome, a genetic pattern which is opposite to those expected among patrilocal populations. Together with previous evidence regarding the possible effects of "local ethnicity" on the genetic structure of German speakers that have settled in the eastern Italian Alps, this finding suggests that taking socio-cultural factors into account together with geographical variables and linguistic diversity may help unveil some yet to be understood

  19. Demographic Histories, Isolation and Social Factors as Determinants of the Genetic Structure of Alpine Linguistic Groups

    PubMed Central

    Coia, Valentina; Capocasa, Marco; Anagnostou, Paolo; Pascali, Vincenzo; Scarnicci, Francesca; Boschi, Ilaria; Battaggia, Cinzia; Crivellaro, Federica; Ferri, Gianmarco; Alù, Milena; Brisighelli, Francesca; Busby, George B. J.; Capelli, Cristian; Maixner, Frank; Cipollini, Giovanna; Viazzo, Pier Paolo; Zink, Albert; Destro Bisol, Giovanni

    2013-01-01

    Great European mountain ranges have acted as barriers to gene flow for resident populations since prehistory and have offered a place for the settlement of small, and sometimes culturally diverse, communities. Therefore, the human groups that have settled in these areas are worth exploring as an important potential source of diversity in the genetic structure of European populations. In this study, we present new high resolution data concerning Y chromosomal variation in three distinct Alpine ethno-linguistic groups, Italian, Ladin and German. Combining unpublished and literature data on Y chromosome and mitochondrial variation, we were able to detect different genetic patterns. In fact, within and among population diversity values observed vary across linguistic groups, with German and Italian speakers at the two extremes, and seem to reflect their different demographic histories. Using simulations we inferred that the joint effect of continued genetic isolation and reduced founding group size may explain the apportionment of genetic diversity observed in all groups. Extending the analysis to other continental populations, we observed that the genetic differentiation of Ladins and German speakers from Europeans is comparable or even greater to that observed for well known outliers like Sardinian and Basques. Finally, we found that in south Tyroleans, the social practice of Geschlossener Hof, a hereditary norm which might have favored male dispersal, coincides with a significant intra-group diversity for mtDNA but not for Y chromosome, a genetic pattern which is opposite to those expected among patrilocal populations. Together with previous evidence regarding the possible effects of “local ethnicity” on the genetic structure of German speakers that have settled in the eastern Italian Alps, this finding suggests that taking socio-cultural factors into account together with geographical variables and linguistic diversity may help unveil some yet to be understood

  20. How the World Survived the Population Bomb: Lessons From 50 Years of Extraordinary Demographic History

    PubMed Central

    Lam, David

    2012-01-01

    The world population will reach 7 billion in late 2011, a demographic milestone that is causing renewed attention to the challenges caused by population growth. This article looks at the last 50 years of demographic change, one of the most extraordinary periods in demographic history. During this period, world population grew at rates that have never been seen before and will almost surely never be seen again. There were many concerns about the potential impact of rapid population growth in the 1960s, including mass starvation in countries such as India, depletion of nonrenewable resources, and increased poverty in low-income countries. The actual experience was very different. World food production increased faster than world population in every decade since the 1960s, resource prices fell during most of the period, and poverty declined significantly in much of the developing world. The article considers the economic and demographic explanations for the surprising successes of this important period in demographic history. It also looks at regions that have been less successful, especially Africa, and at the lessons for dealing with the important challenges that still remain. PMID:22005884

  1. How the world survived the population bomb: lessons from 50 years of extraordinary demographic history.

    PubMed

    Lam, David

    2011-11-01

    The world population will reach 7 billion in late 2011, a demographic milestone that is causing renewed attention to the challenges caused by population growth. This article looks at the last 50 years of demographic change, one of the most extraordinary periods in demographic history. During this period, world population grew at rates that have never been seen before and will almost surely never be seen again. There were many concerns about the potential impact of rapid population growth in the 1960s, including mass starvation in countries such as India, depletion of nonrenewable resources, and increased poverty in low-income countries. The actual experience was very different. World food production increased faster than world population in every decade since the 1960s, resource prices fell during most of the period, and poverty declined significantly in much of the developing world. The article considers the economic and demographic explanations for the surprising successes of this important period in demographic history. It also looks at regions that have been less successful, especially Africa, and at the lessons for dealing with the important challenges that still remain. PMID:22005884

  2. Unification Theory of Optimal Life Histories and Linear Demographic Models in Internal Stochasticity

    PubMed Central

    Oizumi, Ryo

    2014-01-01

    Life history of organisms is exposed to uncertainty generated by internal and external stochasticities. Internal stochasticity is generated by the randomness in each individual life history, such as randomness in food intake, genetic character and size growth rate, whereas external stochasticity is due to the environment. For instance, it is known that the external stochasticity tends to affect population growth rate negatively. It has been shown in a recent theoretical study using path-integral formulation in structured linear demographic models that internal stochasticity can affect population growth rate positively or negatively. However, internal stochasticity has not been the main subject of researches. Taking account of effect of internal stochasticity on the population growth rate, the fittest organism has the optimal control of life history affected by the stochasticity in the habitat. The study of this control is known as the optimal life schedule problems. In order to analyze the optimal control under internal stochasticity, we need to make use of “Stochastic Control Theory” in the optimal life schedule problem. There is, however, no such kind of theory unifying optimal life history and internal stochasticity. This study focuses on an extension of optimal life schedule problems to unify control theory of internal stochasticity into linear demographic models. First, we show the relationship between the general age-states linear demographic models and the stochastic control theory via several mathematical formulations, such as path–integral, integral equation, and transition matrix. Secondly, we apply our theory to a two-resource utilization model for two different breeding systems: semelparity and iteroparity. Finally, we show that the diversity of resources is important for species in a case. Our study shows that this unification theory can address risk hedges of life history in general age-states linear demographic models. PMID:24945258

  3. Multilocus dataset reveals demographic histories of two peat mosses in Europe

    PubMed Central

    Szövényi, Péter; Hock, Zsófia; Schneller, Jakob J; Tóth, Zoltán

    2007-01-01

    Background Revealing the past and present demographic history of populations is of high importance to evaluate the conservation status of species. Demographic data can be obtained by direct monitoring or by analysing data of historical and recent collections. Although these methods provide the most detailed information they are very time consuming. Another alternative way is to make use of the information accumulated in the species' DNA over its history. Recent development of the coalescent theory makes it possible to reconstruct the demographic history of species using nucleotide polymorphism data. To separate the effect of natural selection and demography, multilocus analysis is needed because these two forces can produce similar patterns of polymorphisms. In this study we investigated the amount and pattern of sequence variability of a Europe wide sample set of two peat moss species (Sphagnum fimbriatum and S. squarrosum) with similar distributions and mating systems but presumably contrasting historical demographies using 3 regions of the nuclear genome (appr. 3000 bps). We aimed to draw inferences concerning demographic, and phylogeographic histories of the species. Results All three nuclear regions supported the presence of an Atlantic and Non-Atlantic clade of S. fimbriatum suggesting glacial survival of the species along the Atlantic coast of Europe. Contrarily, S. squarrosum haplotypes showed three clades but no geographic structure at all. Maximum likelihood, mismatch and Bayesian analyses supported a severe historical bottleneck and a relatively recent demographic expansion of the Non-Atlantic clade of S. fimbriatum, whereas size of S. squarrosum populations has probably decreased in the past. Species wide molecular diversity of the two species was nearly the same with an excess of replacement mutations in S. fimbriatum. Similar levels of molecular diversity, contrasting phylogeographic patterns and excess of replacement mutations in S. fimbriatum

  4. Population genetic structure and demographic history of the black fly vector, Simulium nodosum in Thailand.

    PubMed

    Chaiyasan, P; Pramual, P

    2016-09-01

    An understanding of the genetic structure and diversity of vector species is crucial for effective control and management. In this study, mitochondrial DNA sequences were used to examine the genetic structure, diversity and demographic history of a black fly vector, Simulium nodosum Puri (Diptera: Simuliidae), in Thailand. A total of 145 sequences were obtained from 10 sampling locations collected across geographical ranges in the country. Low genetic diversity was found in populations of S. nodosum that could be explained by the recent population history of this species. Demographic history analysis revealed a signature of demographic expansion dating back to only 2600-5200 years ago. Recent population expansion in S. nodosum possibly followed an increase in agriculture that enabled its hosts', humans and domestic animals, densities to increase. Alternatively, the Thai populations could be a derivative of an older expansion event in the more northern populations. Mitochondrial DNA genealogy revealed no genetically divergent lineages, which agrees with the previous cytogenetic study. Genetic structure analyses found that only 27% of the pairwise comparisons were significantly different. The most likely explanation for the pattern of genetic structuring is the effect of genetic drift because of recent colonization.

  5. Population genetic structure and demographic history of the black fly vector, Simulium nodosum in Thailand.

    PubMed

    Chaiyasan, P; Pramual, P

    2016-09-01

    An understanding of the genetic structure and diversity of vector species is crucial for effective control and management. In this study, mitochondrial DNA sequences were used to examine the genetic structure, diversity and demographic history of a black fly vector, Simulium nodosum Puri (Diptera: Simuliidae), in Thailand. A total of 145 sequences were obtained from 10 sampling locations collected across geographical ranges in the country. Low genetic diversity was found in populations of S. nodosum that could be explained by the recent population history of this species. Demographic history analysis revealed a signature of demographic expansion dating back to only 2600-5200 years ago. Recent population expansion in S. nodosum possibly followed an increase in agriculture that enabled its hosts', humans and domestic animals, densities to increase. Alternatively, the Thai populations could be a derivative of an older expansion event in the more northern populations. Mitochondrial DNA genealogy revealed no genetically divergent lineages, which agrees with the previous cytogenetic study. Genetic structure analyses found that only 27% of the pairwise comparisons were significantly different. The most likely explanation for the pattern of genetic structuring is the effect of genetic drift because of recent colonization. PMID:27245148

  6. Statistical inference on genetic data reveals the complex demographic history of human populations in central Asia.

    PubMed

    Palstra, Friso P; Heyer, Evelyne; Austerlitz, Frédéric

    2015-06-01

    The demographic history of modern humans constitutes a combination of expansions, colonizations, contractions, and remigrations. The advent of large scale genetic data combined with statistically refined methods facilitates inference of this complex history. Here we study the demographic history of two genetically admixed ethnic groups in Central Asia, an area characterized by high levels of genetic diversity and a history of recurrent immigration. Using Approximate Bayesian Computation, we infer that the timing of admixture markedly differs between the two groups. Admixture in the traditionally agricultural Tajiks could be dated back to the onset of the Neolithic transition in the region, whereas admixture in Kyrgyz is more recent, and may have involved the westward movement of Turkic peoples. These results are confirmed by a coalescent method that fits an isolation-with-migration model to the genetic data, with both Central Asian groups having received gene flow from the extremities of Eurasia. Interestingly, our analyses also uncover signatures of gene flow from Eastern to Western Eurasia during Paleolithic times. In conclusion, the high genetic diversity currently observed in these two Central Asian peoples most likely reflects the effects of recurrent immigration that likely started before historical times. Conversely, conquests during historical times may have had a relatively limited genetic impact. These results emphasize the need for a better understanding of the genetic consequences of transmission of culture and technological innovations, as well as those of invasions and conquests.

  7. Inferring population structure and demographic history using Y-STR data from worldwide populations.

    PubMed

    Xu, Hongyang; Wang, Chuan-Chao; Shrestha, Rukesh; Wang, Ling-Xiang; Zhang, Manfei; He, Yungang; Kidd, Judith R; Kidd, Kenneth K; Jin, Li; Li, Hui

    2015-02-01

    The Y chromosome is one of the best genetic materials to explore the evolutionary history of human populations. Global analyses of Y chromosomal short tandem repeats (STRs) data can reveal very interesting world population structures and histories. However, previous Y-STR works tended to focus on small geographical ranges or only included limited sample sizes. In this study, we have investigated population structure and demographic history using 17 Y chromosomal STRs data of 979 males from 44 worldwide populations. The largest genetic distances have been observed between pairs of African and non-African populations. American populations with the lowest genetic diversities also showed large genetic distances and coancestry coefficients with other populations, whereas Eurasian populations displayed close genetic affinities. African populations tend to have the oldest time to the most recent common ancestors (TMRCAs), the largest effective population sizes and the earliest expansion times, whereas the American, Siberian, Melanesian, and isolated Atayal populations have the most recent TMRCAs and expansion times, and the smallest effective population sizes. This clear geographic pattern is well consistent with serial founder model for the origin of populations outside Africa. The Y-STR dataset presented here provides the most detailed view of worldwide population structure and human male demographic history, and additionally will be of great benefit to future forensic applications and population genetic studies.

  8. Inferring population structure and demographic history using Y-STR data from worldwide populations.

    PubMed

    Xu, Hongyang; Wang, Chuan-Chao; Shrestha, Rukesh; Wang, Ling-Xiang; Zhang, Manfei; He, Yungang; Kidd, Judith R; Kidd, Kenneth K; Jin, Li; Li, Hui

    2015-02-01

    The Y chromosome is one of the best genetic materials to explore the evolutionary history of human populations. Global analyses of Y chromosomal short tandem repeats (STRs) data can reveal very interesting world population structures and histories. However, previous Y-STR works tended to focus on small geographical ranges or only included limited sample sizes. In this study, we have investigated population structure and demographic history using 17 Y chromosomal STRs data of 979 males from 44 worldwide populations. The largest genetic distances have been observed between pairs of African and non-African populations. American populations with the lowest genetic diversities also showed large genetic distances and coancestry coefficients with other populations, whereas Eurasian populations displayed close genetic affinities. African populations tend to have the oldest time to the most recent common ancestors (TMRCAs), the largest effective population sizes and the earliest expansion times, whereas the American, Siberian, Melanesian, and isolated Atayal populations have the most recent TMRCAs and expansion times, and the smallest effective population sizes. This clear geographic pattern is well consistent with serial founder model for the origin of populations outside Africa. The Y-STR dataset presented here provides the most detailed view of worldwide population structure and human male demographic history, and additionally will be of great benefit to future forensic applications and population genetic studies. PMID:25159112

  9. A life-history perspective on the demographic drivers of structured population dynamics in changing environments.

    PubMed

    Koons, David N; Iles, David T; Schaub, Michael; Caswell, Hal

    2016-09-01

    Current understanding of life-history evolution and how demographic parameters contribute to population dynamics across species is largely based on assumptions of either constant environments or stationary environmental variation. Meanwhile, species are faced with non-stationary environmental conditions (changing mean, variance, or both) created by climate and landscape change. To close the gap between contemporary reality and demographic theory, we develop a set of transient life table response experiments (LTREs) for decomposing realised population growth rates into contributions from specific vital rates and components of population structure. Using transient LTREs in a theoretical framework, we reveal that established concepts in population biology will require revision because of reliance on approaches that do not address the influence of unstable population structure on population growth and mean fitness. Going forward, transient LTREs will enhance understanding of demography and improve the explanatory power of models used to understand ecological and evolutionary dynamics. PMID:27401966

  10. Demographic and mental history-related data predicted occurrence of psychosis in metamphetamine users.

    PubMed

    Farnia, Vahid; Shakeri, Jalal; Tatari, Faezeh; Juibari, Toraj Ahmadi; Bajoghli, Hafez; Golshani, Senoobar; Hookari, Sara; Holsboer-Trachsler, Edith; Brand, Serge

    2016-06-30

    Methamphetamine use is increasing worldwide, and the occurrence of psychosis further complicates treatment. This holds also true for Iran. The aim of the present study was to investigate possible predictors of metamphetamine-induced psychosis. 237 methamphetamine users (70.9% with psychosis; mean age: M=33.41 years) took part in the study. A psychiatric interview was performed covering socio-demographic and illness-related information. Male gender, low education, unemployment, being single, a history of mental disorders, and a higher number of previous hospitalizations predicted the occurrence of psychosis, while age and duration of metamphetamine use were excluded from the equation. Socio-demographic and mental illness-related dimension seemed suitable to predict occurrence of psychosis among metamphetamine abusers.

  11. Life History Traits and Demographic Parameters of Triatoma infestans (Hemiptera: Reduviidae) Fed on Human Blood.

    PubMed

    Medone, Paula; Balsalobre, Agustin; Rabinovich, Jorge E; Marti, Gerardo A; Menu, Frédéric

    2015-11-01

    Triatoma infestans (Klug, 1834) (Hemiptera: Reduviidae), the main vector of Chagas disease in South America, feeds primarily on humans, but ethical reasons preclude carrying out demographical studies using people. Thus, most laboratory studies of T. infestans are conducted using bird or mammal live hosts that may result in different demographic parameters from those obtained on human blood. Therefore, it is of interest to determine whether the use of an artificial feeder with human blood would be operational to rear triatomines and estimate population growth rates. We estimated life history traits and demographic parameters using an artificial feeder with human blood and compared them with those obtained on live hens. Both groups of T. infestans were kept under constant conditions [28 ± 1°C, 40 ± 5% relative humidity, a photoperiod of 12:12 (L:D) h] and fed weekly. On the basis of age-specific survival and age-specific fecundity, we calculated the intrinsic rate of natural increase (r), the finite rate of population growth (λ), the net reproductive rate (Ro), and the mean generation time (Tg). Our results show differences in life history traits between blood sources, resulting in smaller population growth rates on human blood than on live hens. Although demographic growth rate was smaller on human blood than on hens, it still remains positive, so the benefit/cost ratio of this feeding method seems relatively attractive. We discuss possibility of using the artificial feeder with human blood for both ecological and behavioral studies. PMID:26373893

  12. Life History Traits and Demographic Parameters of Triatoma infestans (Hemiptera: Reduviidae) Fed on Human Blood.

    PubMed

    Medone, Paula; Balsalobre, Agustin; Rabinovich, Jorge E; Marti, Gerardo A; Menu, Frédéric

    2015-11-01

    Triatoma infestans (Klug, 1834) (Hemiptera: Reduviidae), the main vector of Chagas disease in South America, feeds primarily on humans, but ethical reasons preclude carrying out demographical studies using people. Thus, most laboratory studies of T. infestans are conducted using bird or mammal live hosts that may result in different demographic parameters from those obtained on human blood. Therefore, it is of interest to determine whether the use of an artificial feeder with human blood would be operational to rear triatomines and estimate population growth rates. We estimated life history traits and demographic parameters using an artificial feeder with human blood and compared them with those obtained on live hens. Both groups of T. infestans were kept under constant conditions [28 ± 1°C, 40 ± 5% relative humidity, a photoperiod of 12:12 (L:D) h] and fed weekly. On the basis of age-specific survival and age-specific fecundity, we calculated the intrinsic rate of natural increase (r), the finite rate of population growth (λ), the net reproductive rate (Ro), and the mean generation time (Tg). Our results show differences in life history traits between blood sources, resulting in smaller population growth rates on human blood than on live hens. Although demographic growth rate was smaller on human blood than on hens, it still remains positive, so the benefit/cost ratio of this feeding method seems relatively attractive. We discuss possibility of using the artificial feeder with human blood for both ecological and behavioral studies.

  13. Life-history evolution in guppies VIII: the demographics of density regulation in guppies (Poecilia reticulata).

    PubMed

    Reznick, David N; Bassar, Ronald D; Travis, Joseph; Helen Rodd, F

    2012-09-01

    In prior research, we found the way guppy life histories evolve in response to living in environments with a high or low risk of predation is consistent with life-history theory that assumes no density dependence. We later found that guppies from high-predation environments experience higher mortality rates than those from low-predation environments, but the increased risk was evenly distributed across all age/size classes. Life-history theory that assumes density-independent population growth predicts that life histories will not evolve under such circumstances, yet we have shown with field introduction experiments that they do evolve. However, theory that incorporates density regulation predicts this pattern of mortality can result in the patterns of life-history evolution we had observed. Here we report on density manipulation experiments performed in populations of guppies from low-predation environments to ask whether natural populations normally experience density regulation and, if so, to characterize the short-term demographic changes that underlie density regulation. Our experiments reveal that these populations are density regulated. Decreased density resulted in higher juvenile growth, decreased juvenile mortality rates, and increased reproductive investment by adult females. Increased density causes reduced offspring size, decreased fat storage by adult females, and increased adult mortality.

  14. Life-history evolution in guppies VIII: the demographics of density regulation in guppies (Poecilia reticulata).

    PubMed

    Reznick, David N; Bassar, Ronald D; Travis, Joseph; Helen Rodd, F

    2012-09-01

    In prior research, we found the way guppy life histories evolve in response to living in environments with a high or low risk of predation is consistent with life-history theory that assumes no density dependence. We later found that guppies from high-predation environments experience higher mortality rates than those from low-predation environments, but the increased risk was evenly distributed across all age/size classes. Life-history theory that assumes density-independent population growth predicts that life histories will not evolve under such circumstances, yet we have shown with field introduction experiments that they do evolve. However, theory that incorporates density regulation predicts this pattern of mortality can result in the patterns of life-history evolution we had observed. Here we report on density manipulation experiments performed in populations of guppies from low-predation environments to ask whether natural populations normally experience density regulation and, if so, to characterize the short-term demographic changes that underlie density regulation. Our experiments reveal that these populations are density regulated. Decreased density resulted in higher juvenile growth, decreased juvenile mortality rates, and increased reproductive investment by adult females. Increased density causes reduced offspring size, decreased fat storage by adult females, and increased adult mortality. PMID:22946811

  15. Estimating genome-wide heterozygosity: effects of demographic history and marker type

    PubMed Central

    Miller, J M; Malenfant, R M; David, P; Davis, C S; Poissant, J; Hogg, J T; Festa-Bianchet, M; Coltman, D W

    2014-01-01

    Heterozygosity–fitness correlations (HFCs) are often used to link individual genetic variation to differences in fitness. However, most studies examining HFCs find weak or no correlations. Here, we derive broad theoretical predictions about how many loci are needed to adequately measure genomic heterozygosity assuming different levels of identity disequilibrium (ID), a proxy for inbreeding. We then evaluate the expected ability to detect HFCs using an empirical data set of 200 microsatellites and 412 single nucleotide polymorphisms (SNPs) genotyped in two populations of bighorn sheep (Ovis canadensis), with different demographic histories. In both populations, heterozygosity was significantly correlated across marker types, although the strength of the correlation was weaker in a native population compared with one founded via translocation and later supplemented with additional individuals. Despite being bi-allelic, SNPs had similar correlations to genome-wide heterozygosity as microsatellites in both populations. For both marker types, this association became stronger and less variable as more markers were considered. Both populations had significant levels of ID; however, estimates were an order of magnitude lower in the native population. As with heterozygosity, SNPs performed similarly to microsatellites, and precision and accuracy of the estimates of ID increased as more loci were considered. Although dependent on the demographic history of the population considered, these results illustrate that genome-wide heterozygosity, and therefore HFCs, are best measured by a large number of markers, a feat now more realistically accomplished with SNPs than microsatellites. PMID:24149650

  16. Demographic history of an elusive carnivore: using museums to inform management.

    PubMed

    Holbrook, Joseph D; Deyoung, Randy W; Tewes, Michael E; Young, John H

    2012-09-01

    Elusive carnivores present a challenge to managers because traditional survey methods are not suitable. We applied a genetic approach using museum specimens to examine how historical and recent conditions influenced the demographic history of Puma concolor in western and southern Texas, USA. We used 10 microsatellite loci and indexed population trends by estimating historical and recent genetic diversity, genetic differentiation and effective population size. Mountain lions in southern Texas exhibited a 9% decline in genetic diversity, whereas diversity remained stable in western Texas. Genetic differentiation between western and southern Texas was minimal historically (F(ST) = 0.04, P < 0.01), but increased 2-2.5 times in our recent sample. An index of genetic drift for southern Texas was seven to eight times that of western Texas, presumably contributing to the current differentiation between western and southern Texas. Furthermore, southern Texas exhibited a >50% temporal decline in effective population size, whereas western Texas showed no change. Our results illustrate that population declines and genetic drift have occurred in southern Texas, likely because of contemporary habitat loss and predator control. Population monitoring may be needed to ensure the persistence of mountain lions in the southern Texas region. This study highlights the utility of sampling museum collections to examine demographic histories and inform wildlife management. PMID:23028402

  17. Demographic history of an elusive carnivore: using museums to inform management

    PubMed Central

    Holbrook, Joseph D; DeYoung, Randy W; Tewes, Michael E; Young, John H

    2012-01-01

    Elusive carnivores present a challenge to managers because traditional survey methods are not suitable. We applied a genetic approach using museum specimens to examine how historical and recent conditions influenced the demographic history of Puma concolor in western and southern Texas, USA. We used 10 microsatellite loci and indexed population trends by estimating historical and recent genetic diversity, genetic differentiation and effective population size. Mountain lions in southern Texas exhibited a 9% decline in genetic diversity, whereas diversity remained stable in western Texas. Genetic differentiation between western and southern Texas was minimal historically (FST = 0.04, P < 0.01), but increased 2–2.5 times in our recent sample. An index of genetic drift for southern Texas was seven to eight times that of western Texas, presumably contributing to the current differentiation between western and southern Texas. Furthermore, southern Texas exhibited a >50% temporal decline in effective population size, whereas western Texas showed no change. Our results illustrate that population declines and genetic drift have occurred in southern Texas, likely because of contemporary habitat loss and predator control. Population monitoring may be needed to ensure the persistence of mountain lions in the southern Texas region. This study highlights the utility of sampling museum collections to examine demographic histories and inform wildlife management. PMID:23028402

  18. Demographic History of Indigenous Populations in Mesoamerica Based on mtDNA Sequence Data.

    PubMed

    González-Martín, Antonio; Gorostiza, Amaya; Regalado-Liu, Lucía; Arroyo-Peña, Sergio; Tirado, Sergio; Nuño-Arana, Ismael; Rubi-Castellanos, Rodrigo; Sandoval, Karla; Coble, Michael D; Rangel-Villalobos, Héctor

    2015-01-01

    The genetic characterization of Native American groups provides insights into their history and demographic events. We sequenced the mitochondrial D-loop region (control region) of 520 samples from eight Mexican indigenous groups. In addition to an analysis of the genetic diversity, structure and genetic relationship between 28 Native American populations, we applied Bayesian skyline methodology for a deeper insight into the history of Mesoamerica. AMOVA tests applying cultural, linguistic and geographic criteria were performed. MDS plots showed a central cluster of Oaxaca and Maya populations, whereas those from the North and West were located on the periphery. Demographic reconstruction indicates higher values of the effective number of breeding females (Nef) in Central Mesoamerica during the Preclassic period, whereas this pattern moves toward the Classic period for groups in the North and West. Conversely, Nef minimum values are distributed either in the Lithic period (i.e. founder effects) or in recent periods (i.e. population declines). The Mesomerican regions showed differences in population fluctuation as indicated by the maximum Inter-Generational Rate (IGRmax): i) Center-South from the lithic period until the Preclassic; ii) West from the beginning of the Preclassic period until early Classic; iii) North characterized by a wide range of temporal variation from the Lithic to the Preclassic. Our findings are consistent with the genetic variations observed between central, South and Southeast Mesoamerica and the North-West region that are related to differences in genetic drift, structure, and temporal survival strategies (agriculture versus hunter-gathering, respectively). Interestingly, although the European contact had a major negative demographic impact, we detect a previous decline in Mesoamerica that had begun a few hundred years before. PMID:26292226

  19. Demographic History of Indigenous Populations in Mesoamerica Based on mtDNA Sequence Data

    PubMed Central

    González-Martín, Antonio; Gorostiza, Amaya; Regalado-Liu, Lucía; Arroyo-Peña, Sergio; Tirado, Sergio; Nuño-Arana, Ismael; Rubi-Castellanos, Rodrigo; Sandoval, Karla; Coble, Michael D.; Rangel-Villalobos, Héctor

    2015-01-01

    The genetic characterization of Native American groups provides insights into their history and demographic events. We sequenced the mitochondrial D-loop region (control region) of 520 samples from eight Mexican indigenous groups. In addition to an analysis of the genetic diversity, structure and genetic relationship between 28 Native American populations, we applied Bayesian skyline methodology for a deeper insight into the history of Mesoamerica. AMOVA tests applying cultural, linguistic and geographic criteria were performed. MDS plots showed a central cluster of Oaxaca and Maya populations, whereas those from the North and West were located on the periphery. Demographic reconstruction indicates higher values of the effective number of breeding females (Nef) in Central Mesoamerica during the Preclassic period, whereas this pattern moves toward the Classic period for groups in the North and West. Conversely, Nef minimum values are distributed either in the Lithic period (i.e. founder effects) or in recent periods (i.e. population declines). The Mesomerican regions showed differences in population fluctuation as indicated by the maximum Inter-Generational Rate (IGRmax): i) Center-South from the lithic period until the Preclassic; ii) West from the beginning of the Preclassic period until early Classic; iii) North characterized by a wide range of temporal variation from the Lithic to the Preclassic. Our findings are consistent with the genetic variations observed between central, South and Southeast Mesoamerica and the North-West region that are related to differences in genetic drift, structure, and temporal survival strategies (agriculture versus hunter-gathering, respectively). Interestingly, although the European contact had a major negative demographic impact, we detect a previous decline in Mesoamerica that had begun a few hundred years before. PMID:26292226

  20. Demographic History of Indigenous Populations in Mesoamerica Based on mtDNA Sequence Data.

    PubMed

    González-Martín, Antonio; Gorostiza, Amaya; Regalado-Liu, Lucía; Arroyo-Peña, Sergio; Tirado, Sergio; Nuño-Arana, Ismael; Rubi-Castellanos, Rodrigo; Sandoval, Karla; Coble, Michael D; Rangel-Villalobos, Héctor

    2015-01-01

    The genetic characterization of Native American groups provides insights into their history and demographic events. We sequenced the mitochondrial D-loop region (control region) of 520 samples from eight Mexican indigenous groups. In addition to an analysis of the genetic diversity, structure and genetic relationship between 28 Native American populations, we applied Bayesian skyline methodology for a deeper insight into the history of Mesoamerica. AMOVA tests applying cultural, linguistic and geographic criteria were performed. MDS plots showed a central cluster of Oaxaca and Maya populations, whereas those from the North and West were located on the periphery. Demographic reconstruction indicates higher values of the effective number of breeding females (Nef) in Central Mesoamerica during the Preclassic period, whereas this pattern moves toward the Classic period for groups in the North and West. Conversely, Nef minimum values are distributed either in the Lithic period (i.e. founder effects) or in recent periods (i.e. population declines). The Mesomerican regions showed differences in population fluctuation as indicated by the maximum Inter-Generational Rate (IGRmax): i) Center-South from the lithic period until the Preclassic; ii) West from the beginning of the Preclassic period until early Classic; iii) North characterized by a wide range of temporal variation from the Lithic to the Preclassic. Our findings are consistent with the genetic variations observed between central, South and Southeast Mesoamerica and the North-West region that are related to differences in genetic drift, structure, and temporal survival strategies (agriculture versus hunter-gathering, respectively). Interestingly, although the European contact had a major negative demographic impact, we detect a previous decline in Mesoamerica that had begun a few hundred years before.

  1. Reconstructing the demographic history of divergence between European river and brook lampreys using approximate Bayesian computations

    PubMed Central

    Roux, Camille; Neuenschwander, Samuel; Goudet, Jérôme; Launey, Sophie; Evanno, Guillaume

    2016-01-01

    Inferring the history of isolation and gene flow during species divergence is a central question in evolutionary biology. The European river lamprey (Lampetra fluviatilis) and brook lamprey (L. planeri) show a low reproductive isolation but have highly distinct life histories, the former being parasitic-anadromous and the latter non-parasitic and freshwater resident. Here we used microsatellite data from six replicated population pairs to reconstruct their history of divergence using an approximate Bayesian computation framework combined with a random forest model. In most population pairs, scenarios of divergence with recent isolation were outcompeted by scenarios proposing ongoing gene flow, namely the Secondary Contact (SC) and Isolation with Migration (IM) models. The estimation of demographic parameters under the SC model indicated a time of secondary contact close to the time of speciation, explaining why SC and IM models could not be discriminated. In case of an ancient secondary contact, the historical signal of divergence is lost and neutral markers converge to the same equilibrium as under the less parameterized model allowing ongoing gene flow. Our results imply that models of secondary contacts should be systematically compared to models of divergence with gene flow; given the difficulty to discriminate among these models, we suggest that genome-wide data are needed to adequately reconstruct divergence history. PMID:27077007

  2. Genomic Insights into the Ancestry and Demographic History of South America

    PubMed Central

    Homburger, Julian R.; Moreno-Estrada, Andrés; Gignoux, Christopher R.; Nelson, Dominic; Sanchez, Elena; Ortiz-Tello, Patricia; Pons-Estel, Bernardo A.; Acevedo-Vasquez, Eduardo; Miranda, Pedro; Langefeld, Carl D.; Gravel, Simon; Alarcón-Riquelme, Marta E.; Bustamante, Carlos D.

    2015-01-01

    South America has a complex demographic history shaped by multiple migration and admixture events in pre- and post-colonial times. Settled over 14,000 years ago by Native Americans, South America has experienced migrations of European and African individuals, similar to other regions in the Americas. However, the timing and magnitude of these events resulted in markedly different patterns of admixture throughout Latin America. We use genome-wide SNP data for 437 admixed individuals from 5 countries (Colombia, Ecuador, Peru, Chile, and Argentina) to explore the population structure and demographic history of South American Latinos. We combined these data with population reference panels from Africa, Asia, Europe and the Americas to perform global ancestry analysis and infer the subcontinental origin of the European and Native American ancestry components of the admixed individuals. By applying ancestry-specific PCA analyses we find that most of the European ancestry in South American Latinos is from the Iberian Peninsula; however, many individuals trace their ancestry back to Italy, especially within Argentina. We find a strong gradient in the Native American ancestry component of South American Latinos associated with country of origin and the geography of local indigenous populations. For example, Native American genomic segments in Peruvians show greater affinities with Andean indigenous peoples like Quechua and Aymara, whereas Native American haplotypes from Colombians tend to cluster with Amazonian and coastal tribes from northern South America. Using ancestry tract length analysis we modeled post-colonial South American migration history as the youngest in Latin America during European colonization (9–14 generations ago), with an additional strong pulse of European migration occurring between 3 and 9 generations ago. These genetic footprints can impact our understanding of population-level differences in biomedical traits and, thus, inform future medical

  3. Genomic Insights into the Ancestry and Demographic History of South America.

    PubMed

    Homburger, Julian R; Moreno-Estrada, Andrés; Gignoux, Christopher R; Nelson, Dominic; Sanchez, Elena; Ortiz-Tello, Patricia; Pons-Estel, Bernardo A; Acevedo-Vasquez, Eduardo; Miranda, Pedro; Langefeld, Carl D; Gravel, Simon; Alarcón-Riquelme, Marta E; Bustamante, Carlos D

    2015-12-01

    South America has a complex demographic history shaped by multiple migration and admixture events in pre- and post-colonial times. Settled over 14,000 years ago by Native Americans, South America has experienced migrations of European and African individuals, similar to other regions in the Americas. However, the timing and magnitude of these events resulted in markedly different patterns of admixture throughout Latin America. We use genome-wide SNP data for 437 admixed individuals from 5 countries (Colombia, Ecuador, Peru, Chile, and Argentina) to explore the population structure and demographic history of South American Latinos. We combined these data with population reference panels from Africa, Asia, Europe and the Americas to perform global ancestry analysis and infer the subcontinental origin of the European and Native American ancestry components of the admixed individuals. By applying ancestry-specific PCA analyses we find that most of the European ancestry in South American Latinos is from the Iberian Peninsula; however, many individuals trace their ancestry back to Italy, especially within Argentina. We find a strong gradient in the Native American ancestry component of South American Latinos associated with country of origin and the geography of local indigenous populations. For example, Native American genomic segments in Peruvians show greater affinities with Andean indigenous peoples like Quechua and Aymara, whereas Native American haplotypes from Colombians tend to cluster with Amazonian and coastal tribes from northern South America. Using ancestry tract length analysis we modeled post-colonial South American migration history as the youngest in Latin America during European colonization (9-14 generations ago), with an additional strong pulse of European migration occurring between 3 and 9 generations ago. These genetic footprints can impact our understanding of population-level differences in biomedical traits and, thus, inform future medical

  4. Demographic History, Population Structure, and Local Adaptation in Alpine Populations of Cardamine impatiens and Cardamine resedifolia

    PubMed Central

    Ometto, Lino; Li, Mingai; Bresadola, Luisa; Barbaro, Enrico; Neteler, Markus; Varotto, Claudio

    2015-01-01

    Species evolution depends on numerous and distinct forces, including demography and natural selection. For example, local adaptation and population structure affect the evolutionary history of species living along environmental clines. This is particularly relevant in plants, which are often characterized by limited dispersal ability and the need to respond to abiotic and biotic stress factors specific to the local environment. Here we study the demographic history and the possible existence of local adaptation in two related species of Brassicaceae, Cardamine impatiens and Cardamine resedifolia, which occupy separate habitats along the elevation gradient. Previous genome-wide analyses revealed the occurrence of distinct selective pressures in the two species, with genes involved in cold response evolving particularly fast in C. resedifolia. In this study we surveyed patterns of molecular evolution and genetic variability in a set of 19 genes, including neutral and candidate genes involved in cold response, across 10 populations each of C. resedifolia and C. impatiens from the Italian Alps (Trentino). We inferred the population structure and demographic history of the two species, and tested the occurrence of signatures of local adaptation in these genes. The results indicate that, despite a slightly higher population differentiation in C. resedifolia than in C. impatiens, both species are only weakly structured and that populations sampled at high altitude experience less gene flow than low-altitude ones. None of the genes showed signatures of positive selection, suggesting that they do not seem to play relevant roles in the current evolutionary processes of adaptation to alpine environments of these species. PMID:25933225

  5. Genomic Insights into the Ancestry and Demographic History of South America.

    PubMed

    Homburger, Julian R; Moreno-Estrada, Andrés; Gignoux, Christopher R; Nelson, Dominic; Sanchez, Elena; Ortiz-Tello, Patricia; Pons-Estel, Bernardo A; Acevedo-Vasquez, Eduardo; Miranda, Pedro; Langefeld, Carl D; Gravel, Simon; Alarcón-Riquelme, Marta E; Bustamante, Carlos D

    2015-12-01

    South America has a complex demographic history shaped by multiple migration and admixture events in pre- and post-colonial times. Settled over 14,000 years ago by Native Americans, South America has experienced migrations of European and African individuals, similar to other regions in the Americas. However, the timing and magnitude of these events resulted in markedly different patterns of admixture throughout Latin America. We use genome-wide SNP data for 437 admixed individuals from 5 countries (Colombia, Ecuador, Peru, Chile, and Argentina) to explore the population structure and demographic history of South American Latinos. We combined these data with population reference panels from Africa, Asia, Europe and the Americas to perform global ancestry analysis and infer the subcontinental origin of the European and Native American ancestry components of the admixed individuals. By applying ancestry-specific PCA analyses we find that most of the European ancestry in South American Latinos is from the Iberian Peninsula; however, many individuals trace their ancestry back to Italy, especially within Argentina. We find a strong gradient in the Native American ancestry component of South American Latinos associated with country of origin and the geography of local indigenous populations. For example, Native American genomic segments in Peruvians show greater affinities with Andean indigenous peoples like Quechua and Aymara, whereas Native American haplotypes from Colombians tend to cluster with Amazonian and coastal tribes from northern South America. Using ancestry tract length analysis we modeled post-colonial South American migration history as the youngest in Latin America during European colonization (9-14 generations ago), with an additional strong pulse of European migration occurring between 3 and 9 generations ago. These genetic footprints can impact our understanding of population-level differences in biomedical traits and, thus, inform future medical

  6. Demographic history and the low genetic diversity in Dipteryx alata (Fabaceae) from Brazilian Neotropical savannas

    PubMed Central

    Collevatti, R G; Telles, M P C; Nabout, J C; Chaves, L J; Soares, T N

    2013-01-01

    Genetic effects of habitat fragmentation may be undetectable because they are generally a recent event in evolutionary time or because of confounding effects such as historical bottlenecks and historical changes in species' distribution. To assess the effects of demographic history on the genetic diversity and population structure in the Neotropical tree Dipteryx alata (Fabaceae), we used coalescence analyses coupled with ecological niche modeling to hindcast its distribution over the last 21 000 years. Twenty-five populations (644 individuals) were sampled and all individuals were genotyped using eight microsatellite loci. All populations presented low allelic richness and genetic diversity. The estimated effective population size was small in all populations and gene flow was negligible among most. We also found a significant signal of demographic reduction in most cases. Genetic differentiation among populations was significantly correlated with geographical distance. Allelic richness showed a spatial cline pattern in relation to the species' paleodistribution 21 kyr BP (thousand years before present), as expected under a range expansion model. Our results show strong evidences that genetic diversity in D. alata is the outcome of the historical changes in species distribution during the late Pleistocene. Because of this historically low effective population size and the low genetic diversity, recent fragmentation of the Cerrado biome may increase population differentiation, causing population decline and compromising long-term persistence. PMID:23591520

  7. Life history and demographic variation in the lizard Sceloporus graciosus: A long-term study

    SciTech Connect

    Tinkle, D.W. ); Dunham, A.E. ); Congdon, J.D. )

    1993-12-01

    An 11-yr study of life history and demographic variation in the sagebrush lizard Sceloporus graciosus was carried out on two study areas (Rattlesnake Ridge and Ponderosa Flat) in the Kolob Mesa Section of Zion National Park, Utah. Two primary objectives of this mark-recapture study were to: (1) quantify variation in age structure, age, and size at maturity, age-specific survivorship and fecundity, and individual growth rates, and (2) conduct a series of density reduction experiments designed to elucidate the effects of density on growth rates and survival of posthatchling lizards. In addition, the authors examined the relationships of variation in population density and deviation from long-term average precipitation and temperature to variation in individual growth, reproduction, and demography. 43 refs., 5 figs., 11 tabs.

  8. Whole-genome sequencing of giant pandas provides insights into demographic history and local adaptation.

    PubMed

    Zhao, Shancen; Zheng, Pingping; Dong, Shanshan; Zhan, Xiangjiang; Wu, Qi; Guo, Xiaosen; Hu, Yibo; He, Weiming; Zhang, Shanning; Fan, Wei; Zhu, Lifeng; Li, Dong; Zhang, Xuemei; Chen, Quan; Zhang, Hemin; Zhang, Zhihe; Jin, Xuelin; Zhang, Jinguo; Yang, Huanming; Wang, Jian; Wang, Jun; Wei, Fuwen

    2013-01-01

    The panda lineage dates back to the late Miocene and ultimately leads to only one extant species, the giant panda (Ailuropoda melanoleuca). Although global climate change and anthropogenic disturbances are recognized to shape animal population demography their contribution to panda population dynamics remains largely unknown. We sequenced the whole genomes of 34 pandas at an average 4.7-fold coverage and used this data set together with the previously deep-sequenced panda genome to reconstruct a continuous demographic history of pandas from their origin to the present. We identify two population expansions, two bottlenecks and two divergences. Evidence indicated that, whereas global changes in climate were the primary drivers of population fluctuation for millions of years, human activities likely underlie recent population divergence and serious decline. We identified three distinct panda populations that show genetic adaptation to their environments. However, in all three populations, anthropogenic activities have negatively affected pandas for 3,000 years. PMID:23242367

  9. Whole-genome sequencing of giant pandas provides insights into demographic history and local adaptation.

    PubMed

    Zhao, Shancen; Zheng, Pingping; Dong, Shanshan; Zhan, Xiangjiang; Wu, Qi; Guo, Xiaosen; Hu, Yibo; He, Weiming; Zhang, Shanning; Fan, Wei; Zhu, Lifeng; Li, Dong; Zhang, Xuemei; Chen, Quan; Zhang, Hemin; Zhang, Zhihe; Jin, Xuelin; Zhang, Jinguo; Yang, Huanming; Wang, Jian; Wang, Jun; Wei, Fuwen

    2013-01-01

    The panda lineage dates back to the late Miocene and ultimately leads to only one extant species, the giant panda (Ailuropoda melanoleuca). Although global climate change and anthropogenic disturbances are recognized to shape animal population demography their contribution to panda population dynamics remains largely unknown. We sequenced the whole genomes of 34 pandas at an average 4.7-fold coverage and used this data set together with the previously deep-sequenced panda genome to reconstruct a continuous demographic history of pandas from their origin to the present. We identify two population expansions, two bottlenecks and two divergences. Evidence indicated that, whereas global changes in climate were the primary drivers of population fluctuation for millions of years, human activities likely underlie recent population divergence and serious decline. We identified three distinct panda populations that show genetic adaptation to their environments. However, in all three populations, anthropogenic activities have negatively affected pandas for 3,000 years.

  10. Costs of fear: Behavioral and life-history responses to risk and their demographic consequences vary across species

    USGS Publications Warehouse

    LaManna, Joseph A.; Martin, Thomas E.

    2016-01-01

    Behavioural responses to reduce predation risk might cause demographic ‘costs of fear’. Costs differ among species, but a conceptual framework to understand this variation is lacking. We use a life-history framework to tie together diverse traits and life stages to better understand interspecific variation in responses and costs. We used natural and experimental variation in predation risk to test phenotypic responses and associated demographic costs for 10 songbird species. Responses such as increased parental attentiveness yielded reduced development time and created benefits such as reduced predation probability. Yet, responses to increased risk also created demographic costs by reducing offspring production in the absence of direct predation. This cost of fear varied widely across species, but predictably with the probability of repeat breeding. Use of a life-history framework can aid our understanding of potential demographic costs from predation, both from responses to perceived risk and from direct predation mortality.

  11. History and demographic composition of the Robert J. Terry anatomical collection.

    PubMed

    Hunt, David R; Albanese, John

    2005-08-01

    Robert J. Terry began collecting human skeletal remains in the area of St. Louis, Missouri for research and educational purposes in 1898. He continued collecting skeletal specimens in the Anatomy Department at Washington University until his retirement in 1941. Mildred Trotter succeeded Terry as anatomy professor and continued his collecting, and strove to balance the demographic distribution of the collection. In 1967, after her retirement, the collection was moved to the Smithsonian Institution's National Museum of Natural History. As with several other well-documented collections, the Terry Collection is widely used for a diverse range of anthropological and medical research. Despite its extensive use, there has been limited discussion of the collection's history and incomplete description of holdings and associated materials of this collection. In this paper, the historical background of the collection and the collection process is described; the demographic composition of the collection, and a description of the documentary and supporting data are presented; and the quality and of these data are assessed. The Terry Collection consists of 1,728 individuals. Age at death ranges from 14-102 years, with the majority of the individuals ranging from 20-80 years. Year of birth ranges from 1828-1943; the mean year of birth for males is 1880, and for females it is 1884. The mean age at death for males is 53 years, and for females it is 58 years. Terry's strict protocols for the processing of cadavers and the recording of documentary data make the Terry Collection a valuable resource for anthropological and medical research.

  12. Neutral nuclear variation in Baboons (genus Papio) provides insights into their evolutionary and demographic histories.

    PubMed

    Boissinot, Stéphane; Alvarez, Lauren; Giraldo-Ramirez, Juliana; Tollis, Marc

    2014-12-01

    Baboons (genus Papio) are distributed over most of sub-Saharan Africa and in the southern portion of the Arabian Peninsula. Six distinct morphotypes, with clearly defined geographic distributions, are recognized (the olive, chacma, yellow, Guinea, Kinda, and hamadryas baboons). The evolutionary relationships among baboon forms have long been a controversial issue. Phylogenetic analyses based on mitochondrial DNA sequences revealed that the modern baboon morphotypes are mitochondrially paraphyletic or polyphyletic. The discordance between mitochondrial lineages and morphology is indicative of extensive introgressive hybridization between ancestral baboon populations. To gain insights into the evolutionary relationships among morphotypes and their demographic history, we performed an analysis of nuclear variation in baboons. We sequenced 13 noncoding, putatively neutral, nuclear regions, and scored the presence/absence of 18 polymorphic transposable elements in a sample of 45 baboons belonging to five of the six recognized baboon forms. We found that the chacma baboon is the sister-taxon to all other baboons and the yellow baboon is the sister-taxon to an unresolved northern clade containing the olive, Guinea, and hamadryas baboons. We estimated that the diversification of baboons occurred entirely in the Pleistocene, the earliest split dating ∼1.5 million years ago, and that baboons have experienced relatively large and constant effective population sizes for most of their evolutionary history (∼30,000 to 95,000 individuals).

  13. Neutral Nuclear Variation in Baboons (genus Papio) Provides Insights into their Evolutionary and Demographic Histories

    PubMed Central

    Boissinot, Stéphane; Alvarez, Lauren; Giraldo-Ramirez, Juliana; Tollis, Marc

    2015-01-01

    Baboons (genus Papio) are distributed over most of sub-Saharan Africa and in the southern portion of the Arabian Peninsula. Six distinct morphotypes, with clearly defined geographic distributions, are recognized (the olive, chacma, yellow, Guinea, Kinda and hamadryas baboons). The evolutionary relationships among baboon forms have long been a controversial issue. Phylogenetic analyses based on mitochondrial DNA sequences revealed that the modern baboon morphotypes are mitochondrially paraphyletic or polyphyletic. The discordance between mitochondrial lineages and morphology is indicative of extensive introgressive hybridization between ancestral baboon populations. To gain insights into the evolutionary relationships among morphotypes and their demographic history, we performed an analysis of nuclear variation in baboons. We sequenced 13 non-coding, putatively neutral, nuclear regions and scored the presence/absence of 18 polymorphic transposable elements in a sample of 45 baboons belonging to five of the six recognized baboon forms. We found that the chacma baboon is the sister-taxon to all other baboons and the yellow baboon is the sister-taxon to an unresolved northern clade containing the olive, Guinea and hamadryas baboons. We estimated that the diversification of baboons occurred entirely in the Pleistocene, the earliest split dating ~1.5 million years ago, and that baboons have experienced relatively large and constant population sizes for most of their evolutionary history (~30,000 to 95,000 individuals). PMID:25234435

  14. Phylogenomics at the tips: inferring lineages and their demographic history in a tropical lizard, Carlia amax.

    PubMed

    Potter, Sally; Bragg, Jason G; Peter, Benjamin M; Bi, Ke; Moritz, Craig

    2016-03-01

    High-throughput sequencing approaches offer opportunities to better understand the evolutionary processes driving diversification, particularly in nonmodel organisms. In particular, the 100-1000's of loci that can now be sequenced are providing unprecedented power in population, speciation and phylogenetic studies. Here, we apply an exon capture approach to generate >99% complete sequence and SNP data across >2000 loci from a tropical skink, Carlia amax, and exploit these data to identify divergent lineages and infer their relationships and demographic histories. This is especially relevant to low-dispersal tropical taxa that often have cryptic diversity and spatially dynamic histories. For C. amax, clustering of nuclear SNPs and coalescent-based species delimitation analyses identify four divergent lineages, one fewer than predicted based on geographically coherent mtDNA clades (>9.4% sequence divergence). Three of these lineages are widespread and parapatric on the mainland, whereas the most divergent is restricted to islands off the northeast Northern Territory. Tests for population expansion reject an equilibrium isolation-by-distance model for two of the three widespread lineages and infer refugial expansion sources in the relatively mesic northeast Top End and northwest Kimberley. The latter is already recognized as a hotspot of endemism, but our results also suggest that a stronger focus on the northeast Top End, and adjacent islands is warranted. More generally, our results show how genome-reduction methods such as exon capture can yield insights into the pattern and dynamics of biodiversity across complex landscapes with as yet poorly understood biogeographic history and how exon data can link between population and phylogenetic questions. PMID:26818481

  15. Population Genetic Structure and Demographic History of Atrina pectinata Based on Mitochondrial DNA and Microsatellite Markers

    PubMed Central

    Xue, Dong-Xiu; Wang, Hai-Yan; Zhang, Tao; Liu, Jin-Xian

    2014-01-01

    The pen shell, Atrina pectinata, is one of the commercial bivalves in East Asia and thought to be recently affected by anthropogenic pressure (habitat destruction and/or fishing pressure). Information on its population genetic structure is crucial for the conservation of A. pectinata. Considering its long pelagic larval duration and iteroparity with high fecundity, the genetic structure for A. pectinata could be expected to be weak at a fine scale. However, the unusual oceanography in the coasts of China and Korea suggests potential for restricted dispersal of pelagic larvae and geographical differentiation. In addition, environmental changes associated with Pleistocene sea level fluctuations on the East China Sea continental shelf may also have strongly influenced historical population demography and genetic diversity of marine organisms. Here, partial sequences of the mitochondrial Cytochrome c oxidase subunit I (COI) gene and seven microsatellite loci were used to estimate population genetic structure and demographic history of seven samples from Northern China coast and one sample from North Korea coast. Despite high levels of genetic diversity within samples, there was no genetic differentiation among samples from Northern China coast and low but significant genetic differentiation between some of the Chinese samples and the North Korean sample. A late Pleistocene population expansion, probably after the Last Glacial Maximum, was also demonstrated for A. pectinata samples. No recent genetic bottleneck was detected in any of the eight samples. We concluded that both historical recolonization (through population range expansion and demographic expansion in the late Pleistocene) and current gene flow (through larval dispersal) were responsible for the weak level of genetic structure detected in A. pectinata. PMID:24789175

  16. Population genetic structure and demographic history of Atrina pectinata based on mitochondrial DNA and microsatellite markers.

    PubMed

    Xue, Dong-Xiu; Wang, Hai-Yan; Zhang, Tao; Liu, Jin-Xian

    2014-01-01

    The pen shell, Atrina pectinata, is one of the commercial bivalves in East Asia and thought to be recently affected by anthropogenic pressure (habitat destruction and/or fishing pressure). Information on its population genetic structure is crucial for the conservation of A. pectinata. Considering its long pelagic larval duration and iteroparity with high fecundity, the genetic structure for A. pectinata could be expected to be weak at a fine scale. However, the unusual oceanography in the coasts of China and Korea suggests potential for restricted dispersal of pelagic larvae and geographical differentiation. In addition, environmental changes associated with Pleistocene sea level fluctuations on the East China Sea continental shelf may also have strongly influenced historical population demography and genetic diversity of marine organisms. Here, partial sequences of the mitochondrial Cytochrome c oxidase subunit I (COI) gene and seven microsatellite loci were used to estimate population genetic structure and demographic history of seven samples from Northern China coast and one sample from North Korea coast. Despite high levels of genetic diversity within samples, there was no genetic differentiation among samples from Northern China coast and low but significant genetic differentiation between some of the Chinese samples and the North Korean sample. A late Pleistocene population expansion, probably after the Last Glacial Maximum, was also demonstrated for A. pectinata samples. No recent genetic bottleneck was detected in any of the eight samples. We concluded that both historical recolonization (through population range expansion and demographic expansion in the late Pleistocene) and current gene flow (through larval dispersal) were responsible for the weak level of genetic structure detected in A. pectinata. PMID:24789175

  17. Demographic histories and genetic diversities of Fennoscandian marine and landlocked ringed seal subspecies

    PubMed Central

    Nyman, Tommi; Valtonen, Mia; Aspi, Jouni; Ruokonen, Minna; Kunnasranta, Mervi; Palo, Jukka U

    2014-01-01

    Island populations are on average smaller, genetically less diverse, and at a higher risk to go extinct than mainland populations. Low genetic diversity may elevate extinction probability, but the genetic component of the risk can be affected by the mode of diversity loss, which, in turn, is connected to the demographic history of the population. Here, we examined the history of genetic erosion in three Fennoscandian ringed seal subspecies, of which one inhabits the Baltic Sea ‘mainland’ and two the ‘aquatic islands’ composed of Lake Saimaa in Finland and Lake Ladoga in Russia. Both lakes were colonized by marine seals after their formation c. 9500 years ago, but Lake Ladoga is larger and more contiguous than Lake Saimaa. All three populations suffered dramatic declines during the 20th century, but the bottleneck was particularly severe in Lake Saimaa. Data from 17 microsatellite loci and mitochondrial control-region sequences show that Saimaa ringed seals have lost most of the genetic diversity present in their Baltic ancestors, while the Ladoga population has experienced only minor reductions. Using Approximate Bayesian computing analyses, we show that the genetic uniformity of the Saimaa subspecies derives from an extended founder event and subsequent slow erosion, rather than from the recent bottleneck. This suggests that the population has persisted for nearly 10,000 years despite having low genetic variation. The relatively high diversity of the Ladoga population appears to result from a high number of initial colonizers and a high post-colonization population size, but possibly also by a shorter isolation period and/or occasional gene flow from the Baltic Sea. PMID:25535558

  18. Demographic histories and genetic diversities of Fennoscandian marine and landlocked ringed seal subspecies.

    PubMed

    Nyman, Tommi; Valtonen, Mia; Aspi, Jouni; Ruokonen, Minna; Kunnasranta, Mervi; Palo, Jukka U

    2014-09-01

    Island populations are on average smaller, genetically less diverse, and at a higher risk to go extinct than mainland populations. Low genetic diversity may elevate extinction probability, but the genetic component of the risk can be affected by the mode of diversity loss, which, in turn, is connected to the demographic history of the population. Here, we examined the history of genetic erosion in three Fennoscandian ringed seal subspecies, of which one inhabits the Baltic Sea 'mainland' and two the 'aquatic islands' composed of Lake Saimaa in Finland and Lake Ladoga in Russia. Both lakes were colonized by marine seals after their formation c. 9500 years ago, but Lake Ladoga is larger and more contiguous than Lake Saimaa. All three populations suffered dramatic declines during the 20th century, but the bottleneck was particularly severe in Lake Saimaa. Data from 17 microsatellite loci and mitochondrial control-region sequences show that Saimaa ringed seals have lost most of the genetic diversity present in their Baltic ancestors, while the Ladoga population has experienced only minor reductions. Using Approximate Bayesian computing analyses, we show that the genetic uniformity of the Saimaa subspecies derives from an extended founder event and subsequent slow erosion, rather than from the recent bottleneck. This suggests that the population has persisted for nearly 10,000 years despite having low genetic variation. The relatively high diversity of the Ladoga population appears to result from a high number of initial colonizers and a high post-colonization population size, but possibly also by a shorter isolation period and/or occasional gene flow from the Baltic Sea.

  19. Demographic history of a recent invasion of house mice on the isolated Island of Gough.

    PubMed

    Gray, Melissa M; Wegmann, Daniel; Haasl, Ryan J; White, Michael A; Gabriel, Sofia I; Searle, Jeremy B; Cuthbert, Richard J; Ryan, Peter G; Payseur, Bret A

    2014-04-01

    Island populations provide natural laboratories for studying key contributors to evolutionary change, including natural selection, population size and the colonization of new environments. The demographic histories of island populations can be reconstructed from patterns of genetic diversity. House mice (Mus musculus) inhabit islands throughout the globe, making them an attractive system for studying island colonization from a genetic perspective. Gough Island, in the central South Atlantic Ocean, is one of the remotest islands in the world. House mice were introduced to Gough Island by sealers during the 19th century and display unusual phenotypes, including exceptionally large body size and carnivorous feeding behaviour. We describe genetic variation in Gough Island mice using mitochondrial sequences, nuclear sequences and microsatellites. Phylogenetic analysis of mitochondrial sequences suggested that Gough Island mice belong to Mus musculus domesticus, with the maternal lineage possibly originating in England or France. Cluster analyses of microsatellites revealed genetic membership for Gough Island mice in multiple coastal populations in Western Europe, suggesting admixed ancestry. Gough Island mice showed substantial reductions in mitochondrial and nuclear sequence variation and weak reductions in microsatellite diversity compared with Western European populations, consistent with a population bottleneck. Approximate Bayesian computation (ABC) estimated that mice recently colonized Gough Island (~100 years ago) and experienced a 98% reduction in population size followed by a rapid expansion. Our results indicate that the unusual phenotypes of Gough Island mice evolved rapidly, positioning these mice as useful models for understanding rapid phenotypic evolution.

  20. Deciphering the Wisent Demographic and Adaptive Histories from Individual Whole-Genome Sequences

    PubMed Central

    Gautier, Mathieu; Moazami-Goudarzi, Katayoun; Levéziel, Hubert; Parinello, Hugues; Grohs, Cécile; Rialle, Stéphanie; Kowalczyk, Rafał; Flori, Laurence

    2016-01-01

    As the largest European herbivore, the wisent (Bison bonasus) is emblematic of the continent wildlife but has unclear origins. Here, we infer its demographic and adaptive histories from two individual whole-genome sequences via a detailed comparative analysis with bovine genomes. We estimate that the wisent and bovine species diverged from 1.7 × 106 to 850,000 years before present (YBP) through a speciation process involving an extended period of limited gene flow. Our data further support the occurrence of more recent secondary contacts, posterior to the Bos taurus and Bos indicus divergence (∼150,000 YBP), between the wisent and (European) taurine cattle lineages. Although the wisent and bovine population sizes experienced a similar sharp decline since the Last Glacial Maximum, we find that the wisent demography remained more fluctuating during the Pleistocene. This is in agreement with a scenario in which wisents responded to successive glaciations by habitat fragmentation rather than southward and eastward migration as for the bovine ancestors. We finally detect 423 genes under positive selection between the wisent and bovine lineages, which shed a new light on the genome response to different living conditions (temperature, available food resource, and pathogen exposure) and on the key gene functions altered by the domestication process. PMID:27436010

  1. Diversification, Biogeographic Pattern, and Demographic History of Taiwanese Scutellaria Species Inferred from Nuclear and Chloroplast DNA

    PubMed Central

    Liao, Pei-Chun

    2012-01-01

    The ragged topography created by orogenesis generates diversified habitats for plants in Taiwan. In addition to colonization from nearby mainland China, high species diversity and endemism of plants is also present in Taiwan. Five of the seven Scutellaria species (Lamiaceae) in Taiwan, for example, are endemic to the island. Hypotheses of multiple sources or in situ radiation have arisen to explain the high endemism of Taiwanese species. In this study, phylogenetic analyses using both nuclear and chloroplast markers revealed the multiple sources of Taiwanese Scutellaria species and confirmed the rapid and recent speciation of endemic species, especially those of the “indica group” composed of S. indica, S. austrotaiwanensis, S. tashiroi, and S. playfairii. The common ancestors of the indica group colonized first in northern Taiwan and dispersed regionally southward and eastward. Climate changes during glacial/interglacial cycles led to gradual colonization and variance events in the ancestors of these species, resulting in the present distribution and genetic differentiation of extant populations. Population decline was also detected in S. indica, which might reflect a bottleneck effect from the glacials. In contrast, the recently speciated endemic members of the indica group have not had enough time to accumulate much genetic variation and are thus genetically insensitive to demographic fluctuations, but the extant lineages were spatially expanded in the coalescent process. This study integrated phylogenetic and population genetic analyses to illustrate the evolutionary history of Taiwanese Scutellaria of high endemism and may be indicative of the diversification mechanism of plants on continental islands. PMID:23226402

  2. Complex population genetic and demographic history of the Salangid, Neosalanx taihuensis, based on cytochrome b sequences

    PubMed Central

    2008-01-01

    Background The Salangid icefish Neosalanx taihuensis (Salangidae) is an economically important fish, which is endemic to China, restricted to large freshwater systems (e.g. lakes, large rivers and estuaries) and typically exhibit low vagility. The continuous distribution ranges from the temperate region of the Huai and Yellow River basins to the subtropical region of the Pearl River basin. This wide ranging distribution makes the species an ideal model for the study of palaeoclimatic effects on population genetic structure and phylogeography. Here, we aim to analyze population genetic differentiation within and between river basins and demographic history in order to understand how this species responded to severe climatic oscillations, decline of the sea levels during the Pleistocene ice ages and tectonic activity. Results We obtained the complete mtDNA cytochrome b sequences (1141 bp) of 354 individuals from 13 populations in the Pearl River, the Yangze River and the Huai River basin. Thirty-six haplotypes were detected. Haplotype frequency distributions were strongly skewed, with most haplotypes (n = 24) represented only in single samples each and thus restricted to a single population. The most common haplotype (H36) was found in 49.15% of all individuals. Analysis of molecular variance (AMOVA) revealed a random pattern in the distribution of genetic diversity, which is inconsistent with contemporary hydrological structure. Significant levels of genetic subdivision were detected among populations within basins rather than between the three basins. Demographic analysis revealed that the population size in the Pearl River basin has remained relatively constant whereas the populations in the Yangze River and the Huai River basins expanded about 221 and 190 kyr ago, respectively, with the majority of mutations occurring after the last glacial maximum (LGM). Conclusion The observed complex genetic pattern of N. taihuensis is coherent with a scenario of multiple

  3. The Evolution of Male-Biased Dispersal under the Joint Selective Forces of Inbreeding Load and Demographic and Environmental Stochasticity.

    PubMed

    Henry, Roslyn C; Coulon, Aurélie; Travis, Justin M J

    2016-10-01

    Sex-biased natal dispersal is widespread, and its significance remains a central question in evolutionary biology. However, theory so far fails to predict some of the most common patterns found in nature. To address this, we present novel results from an individual-based model investigating the joint roles of inbreeding load, demographic stochasticity, environmental stochasticity, and dispersal costs for the evolution of sex-biased dispersal. Most strikingly, we found that male-biased natal dispersal evolved in polygynous systems as a result of the interplay between inbreeding avoidance and stochasticity, whereas previous theory, in contrast to empirical observations, predicted male philopatry and female-biased natal dispersal under inbreeding load alone. Furthermore, the direction of the bias varied according to the nature of stochasticity. Our results therefore provide a unification of previous theory, yielding a much better qualitative match with empirical observations of male-biased dispersal in mate defense mating systems. PMID:27622876

  4. United States -- Mexican joint ventures: A case history approach

    SciTech Connect

    Moore, N.L.; Chidester, R.J.; Hughes, K.R.; Fowler, R.A.

    1993-03-01

    Because the Mexican government has encouraged investment in Mexico by increasing the percentage of ownership of a Mexican business that a US company can hold, joint ventures are more attractive now than they had been in the past. This study provides preliminary information for US renewable energy companies who are interested in forming a joint venture with a Mexican company. This report is not intended to be a complete reference but does identifies a number of important factors that should be observed when forming a Mexican joint venture: (1)Successful joint ventures achieve the goals of each partner. (2)It is essential that all parties agree to the allocation of responsibilities. (3)Put everything in writing. (4)Research in depth the country or countries in which you are considering doing business.

  5. Lifeboat versus corporate ethic: social and demographic implications of stem and joint families.

    PubMed

    Das Gupta, M

    1999-07-01

    We contrast stem and joint family systems, to show how differences in norms of inheritance and residence profoundly influence our values and social constructs. They shape how people evaluate each other and patterns of conflict and cooperation within and between generations. Through this, they influence many fundamental aspects of social organization and behaviour. These influence health outcomes through categorizing people into those whose health is encouraged to prosper or to fail. It also influences a wide range of other outcomes, including strategies of household resource management; migration; ways of exploiting commercial opportunities and the operation of civil society. A number of hypotheses are developed about the nature of these interrelationships, some of which are substantiated empirically and others which can be tested.

  6. Population structure and demographic history of a tropical lowland rainforest tree species Shorea parvifolia (Dipterocarpaceae) from Southeastern Asia.

    PubMed

    Iwanaga, Hiroko; Teshima, Kosuke M; Khatab, Ismael A; Inomata, Nobuyuki; Finkeldey, Reiner; Siregar, Iskandar Z; Siregar, Ulfah J; Szmidt, Alfred E

    2012-07-01

    Distribution of tropical rainforests in Southeastern Asia has changed over geo-logical time scale, due to movement of tectonic plates and/or global climatic changes. Shorea parvifolia is one of the most common tropical lowland rainforest tree species in Southeastern Asia. To infer population structure and demographic history of S. parvifolia, as indicators of temporal changes in the distribution and extent of tropical rainforest in this region, we studied levels and patterns of nucleotide polymorphism in the following five nuclear gene regions: GapC, GBSSI, PgiC, SBE2, and SODH. Seven populations from peninsular Malaysia, Sumatra, and eastern Borneo were included in the analyses. STRUCTURE analysis revealed that the investigated populations are divided into two groups: Sumatra-Malay and Borneo. Furthermore, each group contained one admixed population. Under isolation with migration model, divergence of the two groups was estimated to occur between late Pliocene (2.6 MYA) and middle Pleistocene (0.7 MYA). The log-likelihood ratio tests of several demographic models strongly supported model with population expansion and low level of migration after divergence of the Sumatra-Malay and Borneo groups. The inferred demographic history of S. parvifolia suggested the presence of a scarcely forested land bridge on the Sunda Shelf during glacial periods in the Pleistocene and predominance of tropical lowland rainforest at least in Sumatra and eastern Borneo. PMID:22957170

  7. Population structure and demographic history of a tropical lowland rainforest tree species Shorea parvifolia (Dipterocarpaceae) from Southeastern Asia.

    PubMed

    Iwanaga, Hiroko; Teshima, Kosuke M; Khatab, Ismael A; Inomata, Nobuyuki; Finkeldey, Reiner; Siregar, Iskandar Z; Siregar, Ulfah J; Szmidt, Alfred E

    2012-07-01

    Distribution of tropical rainforests in Southeastern Asia has changed over geo-logical time scale, due to movement of tectonic plates and/or global climatic changes. Shorea parvifolia is one of the most common tropical lowland rainforest tree species in Southeastern Asia. To infer population structure and demographic history of S. parvifolia, as indicators of temporal changes in the distribution and extent of tropical rainforest in this region, we studied levels and patterns of nucleotide polymorphism in the following five nuclear gene regions: GapC, GBSSI, PgiC, SBE2, and SODH. Seven populations from peninsular Malaysia, Sumatra, and eastern Borneo were included in the analyses. STRUCTURE analysis revealed that the investigated populations are divided into two groups: Sumatra-Malay and Borneo. Furthermore, each group contained one admixed population. Under isolation with migration model, divergence of the two groups was estimated to occur between late Pliocene (2.6 MYA) and middle Pleistocene (0.7 MYA). The log-likelihood ratio tests of several demographic models strongly supported model with population expansion and low level of migration after divergence of the Sumatra-Malay and Borneo groups. The inferred demographic history of S. parvifolia suggested the presence of a scarcely forested land bridge on the Sunda Shelf during glacial periods in the Pleistocene and predominance of tropical lowland rainforest at least in Sumatra and eastern Borneo.

  8. Genetic structure and demographic history of the endangered and endemic schizothoracine fish Gymnodiptychus pachycheilus in Qinghai-Tibetan Plateau.

    PubMed

    Su, Junhu; Ji, Weihong; Wei, Yanming; Zhang, Yanping; Gleeson, Dianne M; Lou, Zhongyu; Ren, Jing

    2014-08-01

    The endangered schizothoracine fish Gymnodiptychus pachycheilus is endemic to the Qinghai-Tibetan Plateau (QTP), but very little genetic information is available for this species. Here, we accessed the current genetic divergence of G. pachycheilus population to evaluate their distributions modulated by contemporary and historical processes. Population structure and demographic history were assessed by analyzing 1811-base pairs of mitochondrial DNA from 61 individuals across a large proportion of its geographic range. Our results revealed low nucleotide diversity, suggesting severe historical bottleneck events. Analyses of molecular variance and the conventional population statistic FST (0.0435, P = 0.0215) confirmed weak genetic structure. The monophyly of G. pachycheilus was statistically well-supported, while two divergent evolutionary clusters were identified by phylogenetic analyses, suggesting a microgeographic population structure. The consistent scenario of recent population expansion of two clusters was identified based on several complementary analyses of demographic history (0.096 Ma and 0.15 Ma). This genetic divergence and evolutionary process are likely to have resulted from a series of drainage arrangements triggered by the historical tectonic events of the region. The results obtained here provide the first insights into the evolutionary history and genetic status of this little-known fish.

  9. Genomic Analyses Reveal Demographic History and Temperate Adaptation of the Newly Discovered Honey Bee Subspecies Apis mellifera sinisxinyuan n. ssp

    PubMed Central

    Chen, Chao; Liu, Zhiguang; Pan, Qi; Chen, Xiao; Wang, Huihua; Guo, Haikun; Liu, Shidong; Lu, Hongfeng; Tian, Shilin; Li, Ruiqiang; Shi, Wei

    2016-01-01

    Studying the genetic signatures of climate-driven selection can produce insights into local adaptation and the potential impacts of climate change on populations. The honey bee (Apis mellifera) is an interesting species to study local adaptation because it originated in tropical/subtropical climatic regions and subsequently spread into temperate regions. However, little is known about the genetic basis of its adaptation to temperate climates. Here, we resequenced the whole genomes of ten individual bees from a newly discovered population in temperate China and downloaded resequenced data from 35 individuals from other populations. We found that the new population is an undescribed subspecies in the M-lineage of A. mellifera (Apis mellifera sinisxinyuan). Analyses of population history show that long-term global temperature has strongly influenced the demographic history of A. m. sinisxinyuan and its divergence from other subspecies. Further analyses comparing temperate and tropical populations identified several candidate genes related to fat body and the Hippo signaling pathway that are potentially involved in adaptation to temperate climates. Our results provide insights into the demographic history of the newly discovered A. m. sinisxinyuan, as well as the genetic basis of adaptation of A. mellifera to temperate climates at the genomic level. These findings will facilitate the selective breeding of A. mellifera to improve the survival of overwintering colonies. PMID:26823447

  10. Genomic Analyses Reveal Demographic History and Temperate Adaptation of the Newly Discovered Honey Bee Subspecies Apis mellifera sinisxinyuan n. ssp.

    PubMed

    Chen, Chao; Liu, Zhiguang; Pan, Qi; Chen, Xiao; Wang, Huihua; Guo, Haikun; Liu, Shidong; Lu, Hongfeng; Tian, Shilin; Li, Ruiqiang; Shi, Wei

    2016-05-01

    Studying the genetic signatures of climate-driven selection can produce insights into local adaptation and the potential impacts of climate change on populations. The honey bee (Apis mellifera) is an interesting species to study local adaptation because it originated in tropical/subtropical climatic regions and subsequently spread into temperate regions. However, little is known about the genetic basis of its adaptation to temperate climates. Here, we resequenced the whole genomes of ten individual bees from a newly discovered population in temperate China and downloaded resequenced data from 35 individuals from other populations. We found that the new population is an undescribed subspecies in the M-lineage of A. mellifera (Apis mellifera sinisxinyuan). Analyses of population history show that long-term global temperature has strongly influenced the demographic history of A. m. sinisxinyuan and its divergence from other subspecies. Further analyses comparing temperate and tropical populations identified several candidate genes related to fat body and the Hippo signaling pathway that are potentially involved in adaptation to temperate climates. Our results provide insights into the demographic history of the newly discovered A. m. sinisxinyuan, as well as the genetic basis of adaptation of A. mellifera to temperate climates at the genomic level. These findings will facilitate the selective breeding of A. mellifera to improve the survival of overwintering colonies.

  11. Genomic Analyses Reveal Demographic History and Temperate Adaptation of the Newly Discovered Honey Bee Subspecies Apis mellifera sinisxinyuan n. ssp.

    PubMed

    Chen, Chao; Liu, Zhiguang; Pan, Qi; Chen, Xiao; Wang, Huihua; Guo, Haikun; Liu, Shidong; Lu, Hongfeng; Tian, Shilin; Li, Ruiqiang; Shi, Wei

    2016-05-01

    Studying the genetic signatures of climate-driven selection can produce insights into local adaptation and the potential impacts of climate change on populations. The honey bee (Apis mellifera) is an interesting species to study local adaptation because it originated in tropical/subtropical climatic regions and subsequently spread into temperate regions. However, little is known about the genetic basis of its adaptation to temperate climates. Here, we resequenced the whole genomes of ten individual bees from a newly discovered population in temperate China and downloaded resequenced data from 35 individuals from other populations. We found that the new population is an undescribed subspecies in the M-lineage of A. mellifera (Apis mellifera sinisxinyuan). Analyses of population history show that long-term global temperature has strongly influenced the demographic history of A. m. sinisxinyuan and its divergence from other subspecies. Further analyses comparing temperate and tropical populations identified several candidate genes related to fat body and the Hippo signaling pathway that are potentially involved in adaptation to temperate climates. Our results provide insights into the demographic history of the newly discovered A. m. sinisxinyuan, as well as the genetic basis of adaptation of A. mellifera to temperate climates at the genomic level. These findings will facilitate the selective breeding of A. mellifera to improve the survival of overwintering colonies. PMID:26823447

  12. Heterogeneity of microsatellite mutations within and between loci, and implications for human demographic histories.

    PubMed Central

    Di Rienzo, A; Donnelly, P; Toomajian, C; Sisk, B; Hill, A; Petzl-Erler, M L; Haines, G K; Barch, D H

    1998-01-01

    Microsatellites have been widely used to reconstruct human evolution. However, the efficient use of these markers relies on information regarding the process producing the observed variation. Here, we present a novel approach to the locus-by-locus characterization of this process. By analyzing somatic mutations in cancer patients, we estimated the distributions of mutation size for each of 20 loci. The same loci were then typed in three ethnically diverse population samples. The generalized stepwise mutation model was used to test the predicted relationship between population and mutation parameters under two demographic scenarios: constant population size and rapid expansion. The agreement between the observed and expected relationship between population and mutation parameters, even when the latter are estimated in cancer patients, confirms that somatic mutations may be useful for investigating the process underlying population variation. Estimated distributions of mutation size differ substantially amongst loci, and mutations of more than one repeat unit are common. A new statistic, the normalized population variance, is introduced for multilocus estimation of demographic parameters, and for testing demographic scenarios. The observed population variation is not consistent with a constant population size. Time estimates of the putative population expansion are in agreement with those obtained by other methods. PMID:9539441

  13. Impact of Quaternary climatic changes and interspecific competition on the demographic history of a highly mobile generalist carnivore, the coyote.

    PubMed

    Koblmüller, Stephan; Wayne, Robert K; Leonard, Jennifer A

    2012-08-23

    Recurrent cycles of climatic change during the Quaternary period have dramatically affected the population genetic structure of many species. We reconstruct the recent demographic history of the coyote (Canis latrans) through the use of Bayesian techniques to examine the effects of Late Quaternary climatic perturbations on the genetic structure of a highly mobile generalist species. Our analysis reveals a lack of phylogeographic structure throughout the range but past population size changes correlated with climatic changes. We conclude that even generalist carnivorous species are very susceptible to environmental changes associated with climatic perturbations. This effect may be enhanced in coyotes by interspecific competition with larger carnivores.

  14. Urbanization shapes the demographic history of a native rodent (the white-footed mouse, Peromyscus leucopus) in New York City.

    PubMed

    Harris, Stephen E; Xue, Alexander T; Alvarado-Serrano, Diego; Boehm, Joel T; Joseph, Tyler; Hickerson, Michael J; Munshi-South, Jason

    2016-04-01

    How urbanization shapes population genomic diversity and evolution of urban wildlife is largely unexplored. We investigated the impact of urbanization on white-footed mice,Peromyscus leucopus,in the New York City (NYC) metropolitan area using coalescent-based simulations to infer demographic history from the site-frequency spectrum. We assigned individuals to evolutionary clusters and then inferred recent divergence times, population size changes and migration using genome-wide single nucleotide polymorphisms genotyped in 23 populations sampled along an urban-to-rural gradient. Both prehistoric climatic events and recent urbanization impacted these populations. Our modelling indicates that post-glacial sea-level rise led to isolation of mainland and Long Island populations. These models also indicate that several urban parks represent recently isolated P. leucopus populations, and the estimated divergence times for these populations are consistent with the history of urbanization in NYC. PMID:27072402

  15. Urbanization shapes the demographic history of a native rodent (the white-footed mouse, Peromyscus leucopus) in New York City.

    PubMed

    Harris, Stephen E; Xue, Alexander T; Alvarado-Serrano, Diego; Boehm, Joel T; Joseph, Tyler; Hickerson, Michael J; Munshi-South, Jason

    2016-04-01

    How urbanization shapes population genomic diversity and evolution of urban wildlife is largely unexplored. We investigated the impact of urbanization on white-footed mice,Peromyscus leucopus,in the New York City (NYC) metropolitan area using coalescent-based simulations to infer demographic history from the site-frequency spectrum. We assigned individuals to evolutionary clusters and then inferred recent divergence times, population size changes and migration using genome-wide single nucleotide polymorphisms genotyped in 23 populations sampled along an urban-to-rural gradient. Both prehistoric climatic events and recent urbanization impacted these populations. Our modelling indicates that post-glacial sea-level rise led to isolation of mainland and Long Island populations. These models also indicate that several urban parks represent recently isolated P. leucopus populations, and the estimated divergence times for these populations are consistent with the history of urbanization in NYC.

  16. Inferring the demographic history from DNA sequences: An importance sampling approach based on non-homogeneous processes.

    PubMed

    Ait Kaci Azzou, S; Larribe, F; Froda, S

    2016-10-01

    In Ait Kaci Azzou et al. (2015) we introduced an Importance Sampling (IS) approach for estimating the demographic history of a sample of DNA sequences, the skywis plot. More precisely, we proposed a new nonparametric estimate of a population size that changes over time. We showed on simulated data that the skywis plot can work well in typical situations where the effective population size does not undergo very steep changes. In this paper, we introduce an iterative procedure which extends the previous method and gives good estimates under such rapid variations. In the iterative calibrated skywis plot we approximate the effective population size by a piecewise constant function, whose values are re-estimated at each step. These piecewise constant functions are used to generate the waiting times of non homogeneous Poisson processes related to a coalescent process with mutation under a variable population size model. Moreover, the present IS procedure is based on a modified version of the Stephens and Donnelly (2000) proposal distribution. Finally, we apply the iterative calibrated skywis plot method to a simulated data set from a rapidly expanding exponential model, and we show that the method based on this new IS strategy correctly reconstructs the demographic history.

  17. Effects of mitochondrial DNA rate variation on reconstruction of Pleistocene demographic history in a social avian species, Pomatostomus superciliosus.

    PubMed

    Norman, Janette A; Blackmore, Caroline J; Rourke, Meaghan; Christidis, Les

    2014-01-01

    Mitochondrial sequence data is often used to reconstruct the demographic history of Pleistocene populations in an effort to understand how species have responded to past climate change events. However, departures from neutral equilibrium conditions can confound evolutionary inference in species with structured populations or those that have experienced periods of population expansion or decline. Selection can affect patterns of mitochondrial DNA variation and variable mutation rates among mitochondrial genes can compromise inferences drawn from single markers. We investigated the contribution of these factors to patterns of mitochondrial variation and estimates of time to most recent common ancestor (TMRCA) for two clades in a co-operatively breeding avian species, the white-browed babbler Pomatostomus superciliosus. Both the protein-coding ND3 gene and hypervariable domain I control region sequences showed departures from neutral expectations within the superciliosus clade, and a two-fold difference in TMRCA estimates. Bayesian phylogenetic analysis provided evidence of departure from a strict clock model of molecular evolution in domain I, leading to an over-estimation of TMRCA for the superciliosus clade at this marker. Our results suggest mitochondrial studies that attempt to reconstruct Pleistocene demographic histories should rigorously evaluate data for departures from neutral equilibrium expectations, including variation in evolutionary rates across multiple markers. Failure to do so can lead to serious errors in the estimation of evolutionary parameters and subsequent demographic inferences concerning the role of climate as a driver of evolutionary change. These effects may be especially pronounced in species with complex social structures occupying heterogeneous environments. We propose that environmentally driven differences in social structure may explain observed differences in evolutionary rate of domain I sequences, resulting from longer than

  18. Effects of Mitochondrial DNA Rate Variation on Reconstruction of Pleistocene Demographic History in a Social Avian Species, Pomatostomus superciliosus

    PubMed Central

    Norman, Janette A.; Blackmore, Caroline J.; Rourke, Meaghan; Christidis, Les

    2014-01-01

    Mitochondrial sequence data is often used to reconstruct the demographic history of Pleistocene populations in an effort to understand how species have responded to past climate change events. However, departures from neutral equilibrium conditions can confound evolutionary inference in species with structured populations or those that have experienced periods of population expansion or decline. Selection can affect patterns of mitochondrial DNA variation and variable mutation rates among mitochondrial genes can compromise inferences drawn from single markers. We investigated the contribution of these factors to patterns of mitochondrial variation and estimates of time to most recent common ancestor (TMRCA) for two clades in a co-operatively breeding avian species, the white-browed babbler Pomatostomus superciliosus. Both the protein-coding ND3 gene and hypervariable domain I control region sequences showed departures from neutral expectations within the superciliosus clade, and a two-fold difference in TMRCA estimates. Bayesian phylogenetic analysis provided evidence of departure from a strict clock model of molecular evolution in domain I, leading to an over-estimation of TMRCA for the superciliosus clade at this marker. Our results suggest mitochondrial studies that attempt to reconstruct Pleistocene demographic histories should rigorously evaluate data for departures from neutral equilibrium expectations, including variation in evolutionary rates across multiple markers. Failure to do so can lead to serious errors in the estimation of evolutionary parameters and subsequent demographic inferences concerning the role of climate as a driver of evolutionary change. These effects may be especially pronounced in species with complex social structures occupying heterogeneous environments. We propose that environmentally driven differences in social structure may explain observed differences in evolutionary rate of domain I sequences, resulting from longer than

  19. Altitudinal variation of demographic life-history traits does not mimic latitudinal variation in natterjack toads (Bufo calamita).

    PubMed

    Oromi, Neus; Sanuy, Delfi; Sinsch, Ulrich

    2012-02-01

    In anuran amphibians, age- and size-related life-history traits vary along latitudinal and altiudinal gradients. In the present study, we tested the hypothesis that altitudinal and latitudinal effects cause similar responses by assessing demographic life-history traits in nine Bufo calamita populations inhabiting elevations from sea level to 2270 m. Skeletochronologically determined age at maturity and longevity increased at elevations exceeding 2000 m, but female potential reproductive lifespan (PRLS) did not increase with altitude, as it did with latitude. Integrating the available evidence, it was found that lifetime fecundity of natterjacks decreased at the upper altitudinal range because PRLS was about the same as in lowland populations but females were smaller. In contrast, small size of northern females was compensated for by increased PRLS which minimised latitudinal variation of lifetime fecundity. Thus, this study provides evidence that altitudinal effects on life-history traits do not mimic latitudinal effects. Life-history trait variation along the altitudinal gradient seems to respond directly to the shortening of the annual activity period. As there is no evidence for increasing mortality in highland populations, reduced lifetime fecundity may be the ultimate reason for the natterjacks' inability to colonise elevations exceeding 2500 m.

  20. Genetic signals of past demographic changes and the history of oak populations in California

    NASA Astrophysics Data System (ADS)

    Dodd, R. S.

    2009-04-01

    A retrospective view of species' demographic changes can inform on population stability through times of climatic change and the origins and spatial structure of genetic diversity in contemporary populations. The former provides the means to predict responses to future climatic change, while the latter allows us to infer the ability of populations to buffer the effects of reductions in population size and fragmentation. The approximately 1.8 my of the Pleistocene is believed to have had a significant impact on diversity through high rates of extinction during early glacial cycles and population expansions and contractions during the later cycles. In the Mediterranean basin, early emphasis on taxa with wide latitudinal ranges led to models of refugial sites and subsequent recolonization routes that could explain geographic patterns in genetic diversity, with a trend towards reduced genetic diversity in the north. More recently, the study of strictly Mediterranean taxa has revealed relictual sites that have persisted over very long periods of time, commonly relatively poor in diversity, but populations well differentiated from one site to another. In California, relatively little is known of the population dynamics of plant taxa during the Pleistocene glacial cycles, or to what extent differentiation today is a result of pre-Pleistocene events. For several animal taxa, differentiation between Coastal and Sierran taxa are believed to date to the Pliocene. Major demographic changes resulting in population isolation, bottlenecks, founder events and population expansions leave a genetic signal that can be detected through appropriate genetic markers and analyses. Such signals help to infer whether past climate fluctuations have had important effects on population demographics. Here, I will focus on key oak species of the California mediterranean climate zone. I will explore the likely effects of the last glacial maximum on oak populations using palaeoclimate and niche

  1. Comparative phylogeography and demographic history of the wood lemming (Myopus schisticolor): implications for late Quaternary history of the taiga species in Eurasia.

    PubMed

    Fedorov, V B; Goropashnaya, A V; Boeskorov, G G; Cook, J A

    2008-01-01

    The association between demographic history, genealogy and geographical distribution of mitochondrial DNA cytochrome b haplotypes was studied in the wood lemming (Myopus schisticolor), a species that is closely associated with the boreal forest of the Eurasian taiga zone from Scandinavia to the Pacific coast. Except for a major phylogeographic discontinuity (0.9% nucleotide divergence) in southeastern Siberia, only shallow regional genetic structure was detected across northern Eurasia. Genetic signs of demographic expansions imply that successive range contractions and expansions on different spatial scales represented the primary historical events that shaped geographical patterns of genetic variation. Comparison of phylogeographic structure across a taxonomically diverse array of other species that are ecologically associated with the taiga forest revealed similar patterns and identified two general aspects. First, the major south-north phylogeographic discontinuity observed in five out of six species studied in southeastern Siberia and the Far East implies vicariant separation in two different refugial areas. The limited distribution range of the southeastern lineages provides no evidence of the importance of the putative southeastern refugial area for postglacial colonization of northern Eurasia by boreal forest species. Second, the lack of phylogeographic structure associated with significant reciprocal monophyly and genetic signatures of demographic expansion in all nine boreal forest animal species studied to date across most of northern Eurasia imply contraction of each species to a single refugial area during the late Pleistocene followed by range expansion on a continental scale. Similar phylogeographic patterns observed in this taxonomically diverse set of organisms with different life histories and dispersal potentials reflect the historical dynamics of their shared environment, the taiga forest in northern Eurasia.

  2. Museum DNA reveals the demographic history of the endangered Seychelles warbler

    PubMed Central

    Spurgin, Lewis G; Wright, David J; van der Velde, Marco; Collar, Nigel J; Komdeur, Jan; Burke, Terry; Richardson, David S

    2014-01-01

    The importance of evolutionary conservation – how understanding evolutionary forces can help guide conservation decisions – is widely recognized. However, the historical demography of many endangered species is unknown, despite the fact that this can have important implications for contemporary ecological processes and for extinction risk. Here, we reconstruct the population history of the Seychelles warbler (Acrocephalus sechellensis) – an ecological model species. By the 1960s, this species was on the brink of extinction, but its previous history is unknown. We used DNA samples from contemporary and museum specimens spanning 140 years to reconstruct bottleneck history. We found a 25% reduction in genetic diversity between museum and contemporary populations, and strong genetic structure. Simulations indicate that the Seychelles warbler was bottlenecked from a large population, with an ancestral Ne of several thousands falling to <50 within the last century. Such a rapid decline, due to anthropogenic factors, has important implications for extinction risk in the Seychelles warbler, and our results will inform conservation practices. Reconstructing the population history of this species also allows us to better understand patterns of genetic diversity, inbreeding and promiscuity in the contemporary populations. Our approaches can be applied across species to test ecological hypotheses and inform conservation. PMID:25553073

  3. Museum DNA reveals the demographic history of the endangered Seychelles warbler.

    PubMed

    Spurgin, Lewis G; Wright, David J; van der Velde, Marco; Collar, Nigel J; Komdeur, Jan; Burke, Terry; Richardson, David S

    2014-11-01

    The importance of evolutionary conservation - how understanding evolutionary forces can help guide conservation decisions - is widely recognized. However, the historical demography of many endangered species is unknown, despite the fact that this can have important implications for contemporary ecological processes and for extinction risk. Here, we reconstruct the population history of the Seychelles warbler (Acrocephalus sechellensis) - an ecological model species. By the 1960s, this species was on the brink of extinction, but its previous history is unknown. We used DNA samples from contemporary and museum specimens spanning 140 years to reconstruct bottleneck history. We found a 25% reduction in genetic diversity between museum and contemporary populations, and strong genetic structure. Simulations indicate that the Seychelles warbler was bottlenecked from a large population, with an ancestral N e of several thousands falling to <50 within the last century. Such a rapid decline, due to anthropogenic factors, has important implications for extinction risk in the Seychelles warbler, and our results will inform conservation practices. Reconstructing the population history of this species also allows us to better understand patterns of genetic diversity, inbreeding and promiscuity in the contemporary populations. Our approaches can be applied across species to test ecological hypotheses and inform conservation.

  4. Life History and Demographic Drivers of Reservoir Competence for Three Tick-Borne Zoonotic Pathogens

    PubMed Central

    Ostfeld, Richard S.; Levi, Taal; Jolles, Anna E.; Martin, Lynn B.; Hosseini, Parviez R.; Keesing, Felicia

    2014-01-01

    Animal and plant species differ dramatically in their quality as hosts for multi-host pathogens, but the causes of this variation are poorly understood. A group of small mammals, including small rodents and shrews, are among the most competent natural reservoirs for three tick-borne zoonotic pathogens, Borrelia burgdorferi, Babesia microti, and Anaplasma phagocytophilum, in eastern North America. For a group of nine commonly-infected mammals spanning >2 orders of magnitude in body mass, we asked whether life history features or surrogates for (unknown) encounter rates with ticks, predicted reservoir competence for each pathogen. Life history features associated with a fast pace of life generally were positively correlated with reservoir competence. However, a model comparison approach revealed that host population density, as a proxy for encounter rates between hosts and pathogens, generally received more support than did life history features. The specific life history features and the importance of host population density differed somewhat between the different pathogens. We interpret these results as supporting two alternative but non-exclusive hypotheses for why ecologically widespread, synanthropic species are often the most competent reservoirs for multi-host pathogens. First, multi-host pathogens might adapt to those hosts they are most likely to experience, which are likely to be the most abundant and/or frequently bitten by tick vectors. Second, species with fast life histories might allocate less to certain immune defenses, which could increase their reservoir competence. Results suggest that of the host species that might potentially be exposed, those with comparatively high population densities, small bodies, and fast pace of life will often be keystone reservoirs that should be targeted for surveillance or management. PMID:25232722

  5. Inferring the demographic history of African farmers and pygmy hunter-gatherers using a multilocus resequencing data set.

    PubMed

    Patin, Etienne; Laval, Guillaume; Barreiro, Luis B; Salas, Antonio; Semino, Ornella; Santachiara-Benerecetti, Silvana; Kidd, Kenneth K; Kidd, Judith R; Van der Veen, Lolke; Hombert, Jean-Marie; Gessain, Antoine; Froment, Alain; Bahuchet, Serge; Heyer, Evelyne; Quintana-Murci, Lluís

    2009-04-01

    The transition from hunting and gathering to farming involved a major cultural innovation that has spread rapidly over most of the globe in the last ten millennia. In sub-Saharan Africa, hunter-gatherers have begun to shift toward an agriculture-based lifestyle over the last 5,000 years. Only a few populations still base their mode of subsistence on hunting and gathering. The Pygmies are considered to be the largest group of mobile hunter-gatherers of Africa. They dwell in equatorial rainforests and are characterized by their short mean stature. However, little is known about the chronology of the demographic events-size changes, population splits, and gene flow--ultimately giving rise to contemporary Pygmy (Western and Eastern) groups and neighboring agricultural populations. We studied the branching history of Pygmy hunter-gatherers and agricultural populations from Africa and estimated separation times and gene flow between these populations. We resequenced 24 independent noncoding regions across the genome, corresponding to a total of approximately 33 kb per individual, in 236 samples from seven Pygmy and five agricultural populations dispersed over the African continent. We used simulation-based inference to identify the historical model best fitting our data. The model identified included the early divergence of the ancestors of Pygmy hunter-gatherers and farming populations approximately 60,000 years ago, followed by a split of the Pygmies' ancestors into the Western and Eastern Pygmy groups approximately 20,000 years ago. Our findings increase knowledge of the history of the peopling of the African continent in a region lacking archaeological data. An appreciation of the demographic and adaptive history of African populations with different modes of subsistence should improve our understanding of the influence of human lifestyles on genome diversity.

  6. Demographic History and Reproductive Output Correlates with Intraspecific Genetic Variation in Seven Species of Indo-Pacific Mangrove Crabs.

    PubMed

    Fratini, Sara; Ragionieri, Lapo; Cannicci, Stefano

    2016-01-01

    The spatial distribution and the amount of intraspecific genetic variation of marine organisms are strongly influenced by many biotic and abiotic factors. Comparing biological and genetic data characterizing species living in the same habitat can help to elucidate the processes driving these variation patterns. Here, we present a comparative multispecies population genetic study on seven mangrove crabs co-occurring in the West Indian Ocean characterized by planktotrophic larvae with similar pelagic larval duration. Our main aim was to investigate whether a suite of biological, behavioural and ecological traits could affect genetic diversities of the study species in combination with historical demographic parameters. As possible current explanatory factors, we used the intertidal micro-habitat colonised by adult populations, various parameters of individual and population fecundity, and the timing of larval release. As the genetic marker, we used partial sequences of cytochrome oxidase subunit I gene. Genetic and ecological data were collected by the authors and/or gathered from primary literature. Permutational multiple regression models and ANOVA tests showed that species density and their reproductive output in combination with historical demographic parameters could explain the intraspecific genetic variation indexes across the seven species. In particular, species producing consistently less eggs per spawning event showed higher values of haplotype diversity. Moreover, Tajima's D parameters well explained the recorded values for haplotype diversity and average γst. We concluded that current intraspecific gene diversities in crabs inhabiting mangrove forests were affected by population fecundity as well as past demographic history. The results were also discussed in terms of management and conservation of fauna in the Western Indian Ocean mangroves. PMID:27379532

  7. Demographic History and Reproductive Output Correlates with Intraspecific Genetic Variation in Seven Species of Indo-Pacific Mangrove Crabs

    PubMed Central

    Fratini, Sara; Ragionieri, Lapo; Cannicci, Stefano

    2016-01-01

    The spatial distribution and the amount of intraspecific genetic variation of marine organisms are strongly influenced by many biotic and abiotic factors. Comparing biological and genetic data characterizing species living in the same habitat can help to elucidate the processes driving these variation patterns. Here, we present a comparative multispecies population genetic study on seven mangrove crabs co-occurring in the West Indian Ocean characterized by planktotrophic larvae with similar pelagic larval duration. Our main aim was to investigate whether a suite of biological, behavioural and ecological traits could affect genetic diversities of the study species in combination with historical demographic parameters. As possible current explanatory factors, we used the intertidal micro-habitat colonised by adult populations, various parameters of individual and population fecundity, and the timing of larval release. As the genetic marker, we used partial sequences of cytochrome oxidase subunit I gene. Genetic and ecological data were collected by the authors and/or gathered from primary literature. Permutational multiple regression models and ANOVA tests showed that species density and their reproductive output in combination with historical demographic parameters could explain the intraspecific genetic variation indexes across the seven species. In particular, species producing consistently less eggs per spawning event showed higher values of haplotype diversity. Moreover, Tajima’s D parameters well explained the recorded values for haplotype diversity and average γst. We concluded that current intraspecific gene diversities in crabs inhabiting mangrove forests were affected by population fecundity as well as past demographic history. The results were also discussed in terms of management and conservation of fauna in the Western Indian Ocean mangroves. PMID:27379532

  8. Phylogeography and demographic history of Lacerta lepida in the Iberian Peninsula: multiple refugia, range expansions and secondary contact zones

    PubMed Central

    2011-01-01

    Background The Iberian Peninsula is recognized as an important refugial area for species survival and diversification during the climatic cycles of the Quaternary. Recent phylogeographic studies have revealed Iberia as a complex of multiple refugia. However, most of these studies have focused either on species with narrow distributions within the region or species groups that, although widely distributed, generally have a genetic structure that relates to pre-Quaternary cladogenetic events. In this study we undertake a detailed phylogeographic analysis of the lizard species, Lacerta lepida, whose distribution encompasses the entire Iberian Peninsula. We attempt to identify refugial areas, recolonization routes, zones of secondary contact and date demographic events within this species. Results Results support the existence of 6 evolutionary lineages (phylogroups) with a strong association between genetic variation and geography, suggesting a history of allopatric divergence in different refugia. Diversification within phylogroups is concordant with the onset of the Pleistocene climatic oscillations. The southern regions of several phylogroups show a high incidence of ancestral alleles in contrast with high incidence of recently derived alleles in northern regions. All phylogroups show signs of recent demographic and spatial expansions. We have further identified several zones of secondary contact, with divergent mitochondrial haplotypes occurring in narrow zones of sympatry. Conclusions The concordant patterns of spatial and demographic expansions detected within phylogroups, together with the high incidence of ancestral haplotypes in southern regions of several phylogroups, suggests a pattern of contraction of populations into southern refugia during adverse climatic conditions from which subsequent northern expansions occurred. This study supports the emergent pattern of multiple refugia within Iberia but adds to it by identifying a pattern of refugia coincident

  9. Whole-genome sequence analyses of Western Central African Pygmy hunter-gatherers reveal a complex demographic history and identify candidate genes under positive natural selection

    PubMed Central

    Hsieh, PingHsun; Veeramah, Krishna R.; Lachance, Joseph; Tishkoff, Sarah A.; Wall, Jeffrey D.; Hammer, Michael F.; Gutenkunst, Ryan N.

    2016-01-01

    African Pygmies practicing a mobile hunter-gatherer lifestyle are phenotypically and genetically diverged from other anatomically modern humans, and they likely experienced strong selective pressures due to their unique lifestyle in the Central African rainforest. To identify genomic targets of adaptation, we sequenced the genomes of four Biaka Pygmies from the Central African Republic and jointly analyzed these data with the genome sequences of three Baka Pygmies from Cameroon and nine Yoruba famers. To account for the complex demographic history of these populations that includes both isolation and gene flow, we fit models using the joint allele frequency spectrum and validated them using independent approaches. Our two best-fit models both suggest ancient divergence between the ancestors of the farmers and Pygmies, 90,000 or 150,000 yr ago. We also find that bidirectional asymmetric gene flow is statistically better supported than a single pulse of unidirectional gene flow from farmers to Pygmies, as previously suggested. We then applied complementary statistics to scan the genome for evidence of selective sweeps and polygenic selection. We found that conventional statistical outlier approaches were biased toward identifying candidates in regions of high mutation or low recombination rate. To avoid this bias, we assigned P-values for candidates using whole-genome simulations incorporating demography and variation in both recombination and mutation rates. We found that genes and gene sets involved in muscle development, bone synthesis, immunity, reproduction, cell signaling and development, and energy metabolism are likely to be targets of positive natural selection in Western African Pygmies or their recent ancestors. PMID:26888263

  10. AFRICAN GENETIC DIVERSITY: Implications for Human Demographic History, Modern Human Origins, and Complex Disease Mapping

    PubMed Central

    Campbell, Michael C.; Tishkoff, Sarah A.

    2010-01-01

    Comparative studies of ethnically diverse human populations, particularly in Africa, are important for reconstructing human evolutionary history and for understanding the genetic basis of phenotypic adaptation and complex disease. African populations are characterized by greater levels of genetic diversity, extensive population substructure, and less linkage disequilibrium (LD) among loci compared to non-African populations. Africans also possess a number of genetic adaptations that have evolved in response to diverse climates and diets, as well as exposure to infectious disease. This review summarizes patterns and the evolutionary origins of genetic diversity present in African populations, as well as their implications for the mapping of complex traits, including disease susceptibility. PMID:18593304

  11. Consequences of extreme life history traits on population persistence: do short-lived gobies face demographic bottlenecks?

    NASA Astrophysics Data System (ADS)

    Lefèvre, Carine D.; Nash, Kirsty L.; González-Cabello, Alonso; Bellwood, David R.

    2016-06-01

    The majority of coral reef goby species are short-lived, with some highly abundant species living less than 100 d. To understand the role and consequences of this extreme life history in shaping coral reef fish populations, we quantitatively documented the structure of small reef fish populations over a 26-month period (>14 short-lived fish generations) at an inshore reef on the Great Barrier Reef, Australia. Most species with life spans >1 yr, such as pomacentrids, exhibited a peak in recruitment during the austral summer, driving seasonal changes in the small fish community composition. In contrast, there were no clear changes in goby community composition, despite the abundance of short-lived, high turnover species. Species of Eviota, the most abundant gobiid genus observed, showed remarkably similar demographic profiles year-round, with consistent densities of adults as well as recently recruited juveniles. Our results demonstrate ongoing recruitment of these small cryptic fishes, which appears to compensate for an exceptionally short life span on the reef. Our results suggest that gobiid populations are able to overcome demographic limitations, and by maintaining reproduction, larval survival and recruitment throughout the year, they may avoid population bottlenecks. These findings also underline the potential trophodynamic importance of these small species; because of this constant turnover, Eviota species and other short-lived fishes may be particularly valuable contributors to the flow of energy on coral reefs, underpinning the year-round trophic structure.

  12. Phylogeography of Chinese cherry (Prunus pseudocerasus Lindl.) inferred from chloroplast and nuclear DNA: insights into evolutionary patterns and demographic history.

    PubMed

    Chen, T; Chen, Q; Luo, Y; Huang, Z-L; Zhang, J; Tang, H-R; Pan, D-M; Wang, X-R

    2015-07-01

    Chinese cherry (Prunus pseudocerasus Lindl.) is a commercially valuable fruit crop in China. In order to obtain new insights into its evolutionary history and provide valuable recommendations for resource conservation, phylogeographic patterns of 26 natural populations (305 total individuals) from six geographic regions were analyzed using chloroplast and nuclear DNA fragments. Low levels of haplotype and nucleotide diversity were found in these populations, especially in landrace populations. It is likely that a combined effect of botanical characteristics impact the effective population size, such as inbreeding mating system, long life span, as well as vegetative reproduction. In addition, strong bottleneck effect caused by domestication, together with founder effect after dispersal and subsequent demographic expansion, might also accelerate the reduction of the genetic variation in landrace populations. Interestingly, populations from Longmen Mountain (LMM) and Daliangshan Mountain (DLSM) exhibited relatively higher levels of genetic diversity, inferring the two historical genetic diversity centers of the species. Moreover, moderate population subdivision was also detected by both chloroplast DNA (GST = 0.215; NST = 0.256) and nuclear DNA (GST = 0.146; NST = 0.342), respectively. We inferred that the episodes of efficient gene flow through seed dispersal, together with features of long generation cycle and inbreeding mating system, were likely the main contributors causing the observed phylogeographic patterns. Finally, factors that led to the present demographic patterns of populations from these regions and taxonomic varieties were also discussed.

  13. Contemporary genetic structure and postglacial demographic history of the black scorpionfish, Scorpaena porcus, in the Mediterranean and the Black Seas.

    PubMed

    Boissin, E; Micu, D; Janczyszyn-Le Goff, M; Neglia, V; Bat, L; Todorova, V; Panayotova, M; Kruschel, C; Macic, V; Milchakova, N; Keskin, Ç; Anastasopoulou, A; Nasto, I; Zane, L; Planes, S

    2016-05-01

    Understanding the distribution of genetic diversity in the light of past demographic events linked with climatic shifts will help to forecast evolutionary trajectories of ecosystems within the current context of climate change. In this study, mitochondrial sequences and microsatellite loci were analysed using traditional population genetic approaches together with Bayesian dating and the more recent approximate Bayesian computation scenario testing. The genetic structure and demographic history of a commercial fish, the black scorpionfish, Scorpaena porcus, was investigated throughout the Mediterranean and Black Seas. The results suggest that the species recently underwent population expansions, in both seas, likely concomitant with the warming period following the Last Glacial Maximum, 20 000 years ago. A weak contemporaneous genetic differentiation was identified between the Black Sea and the Mediterranean Sea. However, the genetic diversity was similar for populations of the two seas, suggesting a high number of colonizers entered the Black Sea during the interglacial period and/or the presence of a refugial population in the Black Sea during the glacial period. Finally, within seas, an east/west genetic differentiation in the Adriatic seems to prevail, whereas the Black Sea does not show any structured spatial genetic pattern of its population. Overall, these results suggest that the Black Sea is not that isolated from the Mediterranean, and both seas revealed similar evolutionary patterns related to climate change and changes in sea level. PMID:26989881

  14. Demographic history, marker variability and genetic differentiation in sandy beach fauna: What is the meaning of low FST's?

    NASA Astrophysics Data System (ADS)

    Bezuidenhout, Karien; Nel, Ronel; Hauser, Lorenz

    2014-10-01

    This note demonstrates the effect of locus variability and demographic history on the estimation of genetic differentiation and its interpretation in terms of ecological connectivity. Cytochrome c oxidase subunit I (COI, mtDNA) sequences of the beach clam Donax serra from four sites along the South African coast were analysed. D. serra showed low COI haplotype diversity (h = 0.30 ± 0.069, 7 haplotypes), suggesting expansion from a small source population into extant habitats. As a consequence, statistical power to measure genetic connectivity was low. The lack of genetic population structure therefore does not necessarily demonstrate high connectivity. Although COI has been used successfully to identify species and populations isolated for prolonged periods of time, lack of differentiation has to be interpreted with caution, especially in terms of extant patterns of connectivity.

  15. The Discovery of Single-Nucleotide Polymorphisms—and Inferences about Human Demographic History

    PubMed Central

    Wakeley, John; Nielsen, Rasmus; Liu-Cordero, Shau Neen; Ardlie, Kristin

    2001-01-01

    A method of historical inference that accounts for ascertainment bias is developed and applied to single-nucleotide polymorphism (SNP) data in humans. The data consist of 84 short fragments of the genome that were selected, from three recent SNP surveys, to contain at least two polymorphisms in their respective ascertainment samples and that were then fully resequenced in 47 globally distributed individuals. Ascertainment bias is the deviation, from what would be observed in a random sample, caused either by discovery of polymorphisms in small samples or by locus selection based on levels or patterns of polymorphism. The three SNP surveys from which the present data were derived differ both in their protocols for ascertainment and in the size of the samples used for discovery. We implemented a Monte Carlo maximum-likelihood method to fit a subdivided-population model that includes a possible change in effective size at some time in the past. Incorrectly assuming that ascertainment bias does not exist causes errors in inference, affecting both estimates of migration rates and historical changes in size. Migration rates are overestimated when ascertainment bias is ignored. However, the direction of error in inferences about changes in effective population size (whether the population is inferred to be shrinking or growing) depends on whether either the numbers of SNPs per fragment or the SNP-allele frequencies are analyzed. We use the abbreviation “SDL,” for “SNP-discovered locus,” in recognition of the genomic-discovery context of SNPs. When ascertainment bias is modeled fully, both the number of SNPs per SDL and their allele frequencies support a scenario of growth in effective size in the context of a subdivided population. If subdivision is ignored, however, the hypothesis of constant effective population size cannot be rejected. An important conclusion of this work is that, in demographic or other studies, SNP data are useful only to the extent that

  16. [Mitochondrial DNA sequence variation, demographic history, and population structure of Amur sturgeon Acipenser schrenckii Brandt, 1869].

    PubMed

    Shedko, S V; Miroshnichenko, I L; Nemkova, G A; Koshelev, V N; Shedko, M B

    2015-02-01

    The variability of the mtDNA control region (D-loop) was examined in Amur sturgeon endemic to the Amur River. This species is also classified as critically endangered by the IUCN Red List of Threatened species. Sequencing of 796- to 812-bp fragments of the D-loop in 112 sturgeon collected in the Lower Amur revealed 73 different genotypes. The sample was characterized by a high level of haplotypic (0.976) and nucleotide (0.0194) diversity. The identified haplotypes split into two well-defined monophyletic groups, BG (n = 39) and SM (n = 34), differing (HKY distance) on average by 3.41% of nucleotide positions upon an average level of intragroup differences of 0.54 and 1.23%, respectively. Moreover, the haplotypes of the SM groups differed by the presence of a 13-14 bp deletion. Most ofthe samples (66 out of 112) carried BG haplotypes. Overall, the pattern of pairwise nucleotide differences and the results of neutrality tests, as well as the results of tests for compliance with the model of sudden demographic expansion or with the model of exponential growth pointed to a past significant increase in the number of Amur sturgeon, which was most clearly manifested in the analysis of data on the BG haplogroup. The constructed Bayesian skyline plots showed that this growth began about 18 to 16 thousand years ago. At present, the effective size of the strongly reduced (due to overharvesting) population of Amur sturgeon may be equal to or even lower than it was before the beginning of this growth during the Last Glacial Maximum. The presence in the mitochondrial gene pool ofAmur sturgeon of two haplogroups, their unequal evolutionary dynamics, and, judging by scanty data, their unequal representation in the Russian and Chinese parts of the Amur River basin point to the possible existence of at least two distinct populations of Amur sturgeon in the past. PMID:25966586

  17. [Mitochondrial DNA sequence variation, demographic history, and population structure of Amur sturgeon Acipenser schrenckii Brandt, 1869].

    PubMed

    Shedko, S V; Miroshnichenko, I L; Nemkova, G A; Koshelev, V N; Shedko, M B

    2015-02-01

    The variability of the mtDNA control region (D-loop) was examined in Amur sturgeon endemic to the Amur River. This species is also classified as critically endangered by the IUCN Red List of Threatened species. Sequencing of 796- to 812-bp fragments of the D-loop in 112 sturgeon collected in the Lower Amur revealed 73 different genotypes. The sample was characterized by a high level of haplotypic (0.976) and nucleotide (0.0194) diversity. The identified haplotypes split into two well-defined monophyletic groups, BG (n = 39) and SM (n = 34), differing (HKY distance) on average by 3.41% of nucleotide positions upon an average level of intragroup differences of 0.54 and 1.23%, respectively. Moreover, the haplotypes of the SM groups differed by the presence of a 13-14 bp deletion. Most ofthe samples (66 out of 112) carried BG haplotypes. Overall, the pattern of pairwise nucleotide differences and the results of neutrality tests, as well as the results of tests for compliance with the model of sudden demographic expansion or with the model of exponential growth pointed to a past significant increase in the number of Amur sturgeon, which was most clearly manifested in the analysis of data on the BG haplogroup. The constructed Bayesian skyline plots showed that this growth began about 18 to 16 thousand years ago. At present, the effective size of the strongly reduced (due to overharvesting) population of Amur sturgeon may be equal to or even lower than it was before the beginning of this growth during the Last Glacial Maximum. The presence in the mitochondrial gene pool ofAmur sturgeon of two haplogroups, their unequal evolutionary dynamics, and, judging by scanty data, their unequal representation in the Russian and Chinese parts of the Amur River basin point to the possible existence of at least two distinct populations of Amur sturgeon in the past.

  18. Inference of gorilla demographic and selective history from whole-genome sequence data.

    PubMed

    McManus, Kimberly F; Kelley, Joanna L; Song, Shiya; Veeramah, Krishna R; Woerner, August E; Stevison, Laurie S; Ryder, Oliver A; Ape Genome Project, Great; Kidd, Jeffrey M; Wall, Jeffrey D; Bustamante, Carlos D; Hammer, Michael F

    2015-03-01

    Although population-level genomic sequence data have been gathered extensively for humans, similar data from our closest living relatives are just beginning to emerge. Examination of genomic variation within great apes offers many opportunities to increase our understanding of the forces that have differentially shaped the evolutionary history of hominid taxa. Here, we expand upon the work of the Great Ape Genome Project by analyzing medium to high coverage whole-genome sequences from 14 western lowland gorillas (Gorilla gorilla gorilla), 2 eastern lowland gorillas (G. beringei graueri), and a single Cross River individual (G. gorilla diehli). We infer that the ancestors of western and eastern lowland gorillas diverged from a common ancestor approximately 261 ka, and that the ancestors of the Cross River population diverged from the western lowland gorilla lineage approximately 68 ka. Using a diffusion approximation approach to model the genome-wide site frequency spectrum, we infer a history of western lowland gorillas that includes an ancestral population expansion of 1.4-fold around 970 ka and a recent 5.6-fold contraction in population size 23 ka. The latter may correspond to a major reduction in African equatorial forests around the Last Glacial Maximum. We also analyze patterns of variation among western lowland gorillas to identify several genomic regions with strong signatures of recent selective sweeps. We find that processes related to taste, pancreatic and saliva secretion, sodium ion transmembrane transport, and cardiac muscle function are overrepresented in genomic regions predicted to have experienced recent positive selection.

  19. Blacktip reef sharks, Carcharhinus melanopterus, have high genetic structure and varying demographic histories in their Indo-Pacific range.

    PubMed

    Vignaud, Thomas M; Mourier, Johann; Maynard, Jeffrey A; Leblois, Raphael; Spaet, Julia; Clua, Eric; Neglia, Valentina; Planes, Serge

    2014-11-01

    For free-swimming marine species like sharks, only population genetics and demographic history analyses can be used to assess population health/status as baseline population numbers are usually unknown. We investigated the population genetics of blacktip reef sharks, Carcharhinus melanopterus; one of the most abundant reef-associated sharks and the apex predator of many shallow water reefs of the Indian and Pacific Oceans. Our sampling includes 4 widely separated locations in the Indo-Pacific and 11 islands in French Polynesia with different levels of coastal development. Four-teen microsatellite loci were analysed for samples from all locations and two mitochondrial DNA fragments, the control region and cytochrome b, were examined for 10 locations. For microsatellites, genetic diversity is higher for the locations in the large open systems of the Red Sea and Australia than for the fragmented habitat of the smaller islands of French Polynesia. Strong significant structure was found for distant locations with FST values as high as ~0.3, and a smaller but still significant structure is found within French Polynesia. Both mitochondrial genes show only a few mutations across the sequences with a dominant shared haplotype in French Polynesia and New Caledonia suggesting a common lineage different to that of East Australia. Demographic history analyses indicate population expansions in the Red Sea and Australia that may coincide with sea level changes after climatic events. Expansions and flat signals are indicated for French Polynesia as well as a significant recent bottleneck for Moorea, the most human-impacted lagoon of the locations in French Polynesia.

  20. Utilizing Spatial Demographic and Life History Variation to Optimize Sustainable Yield of a Temperate Sex-Changing Fish

    PubMed Central

    Hamilton, Scott L.; Wilson, Jono R.; Ben-Horin, Tal; Caselle, Jennifer E.

    2011-01-01

    Fish populations vary geographically in demography and life history due to environmental and ecological processes and in response to exploitation. However, population dynamic models and stock assessments, used to manage fisheries, rarely explicitly incorporate spatial variation to inform management decisions. Here, we describe extensive geographic variation in several demographic and life history characteristics (e.g., size structure, growth, survivorship, maturation, and sex change) of California sheephead (Semicossyphus pulcher), a temperate rocky reef fish targeted by recreational and commercial fisheries. Fish were sampled from nine locations throughout southern California in 2007–2008. We developed a dynamic size and age-structured model, parameterized separately for each location, to assess the potential cost or benefit in terms of fisheries yield and conservation objectives of changing minimum size limits and/or fishing mortality rates (compared to the status quo). Results indicate that managing populations individually, with location-specific regulations, could increase yield by over 26% while maintaining conservative levels of spawning biomass. While this local management approach would be challenging to implement in practice, we found statistically similar increases in yield could be achieved by dividing southern California into two separate management regions, reflecting geographic similarities in demography. To maximize yield, size limits should be increased by 90 mm in the northern region and held at current levels in the south. We also found that managing the fishery as one single stock (the status quo), but with a size limit 50 mm greater than the current regulations, could increase overall fishery yield by 15%. Increases in size limits are predicted to enhance fishery yield and may also have important ecological consequences for the predatory role of sheephead in kelp forests. This framework for incorporating demographic variation into fisheries

  1. Genetic diversity, genetic structure and demographic history of Cycas simplicipinna (Cycadaceae) assessed by DNA sequences and SSR markers

    PubMed Central

    2014-01-01

    Background Cycas simplicipinna (T. Smitinand) K. Hill. (Cycadaceae) is an endangered species in China. There were seven populations and 118 individuals that we could collect were genotyped in this study. Here, we assessed the genetic diversity, genetic structure and demographic history of this species. Results Analyses of data of DNA sequences (two maternally inherited intergenic spacers of chloroplast, cpDNA and one biparentally inherited internal transcribed spacer region ITS4-ITS5, nrDNA) and sixteen microsatellite loci (SSR) were conducted in the species. Of the 118 samples, 86 individuals from the seven populations were used for DNA sequencing and 115 individuals from six populations were used for the microsatellite study. We found high genetic diversity at the species level, low genetic diversity within each of the seven populations and high genetic differentiation among the populations. There was a clear genetic structure within populations of C. simplicipinna. A demographic history inferred from DNA sequencing data indicates that C. simplicipinna experienced a recent population contraction without retreating to a common refugium during the last glacial period. The results derived from SSR data also showed that C. simplicipinna underwent past effective population contraction, likely during the Pleistocene. Conclusions Some genetic features of C. simplicipinna such as having high genetic differentiation among the populations, a clear genetic structure and a recent population contraction could provide guidelines for protecting this endangered species from extinction. Furthermore, the genetic features with population dynamics of the species in our study would help provide insights and guidelines for protecting other endangered species effectively. PMID:25016306

  2. Blacktip reef sharks, Carcharhinus melanopterus, have high genetic structure and varying demographic histories in their Indo-Pacific range.

    PubMed

    Vignaud, Thomas M; Mourier, Johann; Maynard, Jeffrey A; Leblois, Raphael; Spaet, Julia; Clua, Eric; Neglia, Valentina; Planes, Serge

    2014-11-01

    For free-swimming marine species like sharks, only population genetics and demographic history analyses can be used to assess population health/status as baseline population numbers are usually unknown. We investigated the population genetics of blacktip reef sharks, Carcharhinus melanopterus; one of the most abundant reef-associated sharks and the apex predator of many shallow water reefs of the Indian and Pacific Oceans. Our sampling includes 4 widely separated locations in the Indo-Pacific and 11 islands in French Polynesia with different levels of coastal development. Four-teen microsatellite loci were analysed for samples from all locations and two mitochondrial DNA fragments, the control region and cytochrome b, were examined for 10 locations. For microsatellites, genetic diversity is higher for the locations in the large open systems of the Red Sea and Australia than for the fragmented habitat of the smaller islands of French Polynesia. Strong significant structure was found for distant locations with FST values as high as ~0.3, and a smaller but still significant structure is found within French Polynesia. Both mitochondrial genes show only a few mutations across the sequences with a dominant shared haplotype in French Polynesia and New Caledonia suggesting a common lineage different to that of East Australia. Demographic history analyses indicate population expansions in the Red Sea and Australia that may coincide with sea level changes after climatic events. Expansions and flat signals are indicated for French Polynesia as well as a significant recent bottleneck for Moorea, the most human-impacted lagoon of the locations in French Polynesia. PMID:25251515

  3. Inference of gorilla demographic and selective history from whole-genome sequence data.

    PubMed

    McManus, Kimberly F; Kelley, Joanna L; Song, Shiya; Veeramah, Krishna R; Woerner, August E; Stevison, Laurie S; Ryder, Oliver A; Ape Genome Project, Great; Kidd, Jeffrey M; Wall, Jeffrey D; Bustamante, Carlos D; Hammer, Michael F

    2015-03-01

    Although population-level genomic sequence data have been gathered extensively for humans, similar data from our closest living relatives are just beginning to emerge. Examination of genomic variation within great apes offers many opportunities to increase our understanding of the forces that have differentially shaped the evolutionary history of hominid taxa. Here, we expand upon the work of the Great Ape Genome Project by analyzing medium to high coverage whole-genome sequences from 14 western lowland gorillas (Gorilla gorilla gorilla), 2 eastern lowland gorillas (G. beringei graueri), and a single Cross River individual (G. gorilla diehli). We infer that the ancestors of western and eastern lowland gorillas diverged from a common ancestor approximately 261 ka, and that the ancestors of the Cross River population diverged from the western lowland gorilla lineage approximately 68 ka. Using a diffusion approximation approach to model the genome-wide site frequency spectrum, we infer a history of western lowland gorillas that includes an ancestral population expansion of 1.4-fold around 970 ka and a recent 5.6-fold contraction in population size 23 ka. The latter may correspond to a major reduction in African equatorial forests around the Last Glacial Maximum. We also analyze patterns of variation among western lowland gorillas to identify several genomic regions with strong signatures of recent selective sweeps. We find that processes related to taste, pancreatic and saliva secretion, sodium ion transmembrane transport, and cardiac muscle function are overrepresented in genomic regions predicted to have experienced recent positive selection. PMID:25534031

  4. Nautilus pompilius life history and demographics at the Osprey Reef Seamount, Coral Sea, Australia.

    PubMed

    Dunstan, Andrew J; Ward, Peter D; Marshall, N Justin

    2011-01-01

    Nautiloids are the subject of speculation as to their threatened status arising from the impacts of targeted fishing for the ornamental shell market. Life history knowledge is essential to understand the susceptibility of this group to overfishing and to the instigation of management frameworks. This study provides a comprehensive insight into the life of Nautilus in the wild. At Osprey Reef from 1998-2008, trapping for Nautilus was conducted on 354 occasions, with 2460 individuals of one species, Nautilus pompilius, captured and 247 individuals recaptured. Baited remote underwater video systems (BRUVS) were deployed on 15 occasions and six remotely operated vehicle (ROV) dives from 100-800 m were conducted to record Nautilus presence and behavior. Maturity, sex and size data were recorded, while measurements of recaptured individuals allowed estimation of growth rates to maturity, and longevity beyond maturity. We found sexual dimorphism in size at maturity (males: 131.9±SD = 2.6 mm; females: 118.9±7.5 mm shell diameter) in a population dominated by mature individuals (58%). Mean growth rates of 15 immature recaptured animals were 0.061±0.023 mm day(-1) resulting in an estimate of around 15.5 years to maturation. Recaptures of mature animals after five years provide evidence of a lifespan exceeding 20 years. Juvenile Nautilus pompilius feeding behavior was recorded for the first time within the same depth range (200-610 m) as adults. Our results provide strong evidence of a K-selected life history for Nautilus from a detailed study of a 'closed' wild population. In conjunction with population size and density estimates established for the Osprey Reef Nautilus, this work allows calculations for sustainable catch and provides mechanisms to extrapolate these findings to other extant nautiloid populations (Nautilus and Allonautilus spp.) throughout the Indo-Pacific. PMID:21347356

  5. Inference of Gorilla Demographic and Selective History from Whole-Genome Sequence Data

    PubMed Central

    McManus, Kimberly F.; Kelley, Joanna L.; Song, Shiya; Veeramah, Krishna R.; Woerner, August E.; Stevison, Laurie S.; Ryder, Oliver A.; Ape Genome Project, Great; Kidd, Jeffrey M.; Wall, Jeffrey D.; Bustamante, Carlos D.; Hammer, Michael F.

    2015-01-01

    Although population-level genomic sequence data have been gathered extensively for humans, similar data from our closest living relatives are just beginning to emerge. Examination of genomic variation within great apes offers many opportunities to increase our understanding of the forces that have differentially shaped the evolutionary history of hominid taxa. Here, we expand upon the work of the Great Ape Genome Project by analyzing medium to high coverage whole-genome sequences from 14 western lowland gorillas (Gorilla gorilla gorilla), 2 eastern lowland gorillas (G. beringei graueri), and a single Cross River individual (G. gorilla diehli). We infer that the ancestors of western and eastern lowland gorillas diverged from a common ancestor approximately 261 ka, and that the ancestors of the Cross River population diverged from the western lowland gorilla lineage approximately 68 ka. Using a diffusion approximation approach to model the genome-wide site frequency spectrum, we infer a history of western lowland gorillas that includes an ancestral population expansion of 1.4-fold around 970 ka and a recent 5.6-fold contraction in population size 23 ka. The latter may correspond to a major reduction in African equatorial forests around the Last Glacial Maximum. We also analyze patterns of variation among western lowland gorillas to identify several genomic regions with strong signatures of recent selective sweeps. We find that processes related to taste, pancreatic and saliva secretion, sodium ion transmembrane transport, and cardiac muscle function are overrepresented in genomic regions predicted to have experienced recent positive selection. PMID:25534031

  6. Nautilus pompilius life history and demographics at the Osprey Reef Seamount, Coral Sea, Australia.

    PubMed

    Dunstan, Andrew J; Ward, Peter D; Marshall, N Justin

    2011-01-01

    Nautiloids are the subject of speculation as to their threatened status arising from the impacts of targeted fishing for the ornamental shell market. Life history knowledge is essential to understand the susceptibility of this group to overfishing and to the instigation of management frameworks. This study provides a comprehensive insight into the life of Nautilus in the wild. At Osprey Reef from 1998-2008, trapping for Nautilus was conducted on 354 occasions, with 2460 individuals of one species, Nautilus pompilius, captured and 247 individuals recaptured. Baited remote underwater video systems (BRUVS) were deployed on 15 occasions and six remotely operated vehicle (ROV) dives from 100-800 m were conducted to record Nautilus presence and behavior. Maturity, sex and size data were recorded, while measurements of recaptured individuals allowed estimation of growth rates to maturity, and longevity beyond maturity. We found sexual dimorphism in size at maturity (males: 131.9±SD = 2.6 mm; females: 118.9±7.5 mm shell diameter) in a population dominated by mature individuals (58%). Mean growth rates of 15 immature recaptured animals were 0.061±0.023 mm day(-1) resulting in an estimate of around 15.5 years to maturation. Recaptures of mature animals after five years provide evidence of a lifespan exceeding 20 years. Juvenile Nautilus pompilius feeding behavior was recorded for the first time within the same depth range (200-610 m) as adults. Our results provide strong evidence of a K-selected life history for Nautilus from a detailed study of a 'closed' wild population. In conjunction with population size and density estimates established for the Osprey Reef Nautilus, this work allows calculations for sustainable catch and provides mechanisms to extrapolate these findings to other extant nautiloid populations (Nautilus and Allonautilus spp.) throughout the Indo-Pacific.

  7. Genetic structuring and recent demographic history of red pandas (Ailurus fulgens) inferred from microsatellite and mitochondrial DNA.

    PubMed

    Hu, Yibo; Guo, Yu; Qi, Dunwu; Zhan, Xiangjiang; Wu, Hua; Bruford, Michael W; Wei, Fuwen

    2011-07-01

    Clarification of the genetic structure and population history of a species can shed light on the impacts of landscapes, historical climate change and contemporary human activities and thus enables evidence-based conservation decisions for endangered organisms. The red panda (Ailurus fulgens) is an endangered species distributing at the edge of the Qinghai-Tibetan Plateau and is currently subject to habitat loss, fragmentation and population decline, thus representing a good model to test the influences of the above-mentioned factors on a plateau edge species. We combined nine microsatellite loci and 551 bp of mitochondrial control region (mtDNA CR) to explore the genetic structure and demographic history of this species. A total of 123 individuals were sampled from 23 locations across five populations. High levels of genetic variation were identified for both mtDNA and microsatellites. Phylogeographic analyses indicated little geographic structure, suggesting historically wide gene flow. However, microsatellite-based Bayesian clustering clearly identified three groups (Qionglai-Liangshan, Xiaoxiangling and Gaoligong-Tibet). A significant isolation-by-distance pattern was detected only after removing Xiaoxiangling. For mtDNA data, there was no statistical support for a historical population expansion or contraction for the whole sample or any population except Xiaoxiangling where a signal of contraction was detected. However, Bayesian simulations of population history using microsatellite data did pinpoint population declines for Qionglai, Xiaoxiangling and Gaoligong, demonstrating significant influences of human activity on demography. The unique history of the Xiaoxiangling population plays a critical role in shaping the genetic structure of this species, and large-scale habitat loss and fragmentation is hampering gene flow among populations. The implications of our findings for the biogeography of the Qinghai-Tibetan Plateau, subspecies classification and

  8. Contrasting demographic history and gene flow patterns of two mangrove species on either side of the Central American Isthmus.

    PubMed

    Cerón-Souza, Ivania; Gonzalez, Elena G; Schwarzbach, Andrea E; Salas-Leiva, Dayana E; Rivera-Ocasio, Elsie; Toro-Perea, Nelson; Bermingham, Eldredge; McMillan, W Owen

    2015-08-01

    Comparative phylogeography offers a unique opportunity to understand the interplay between past environmental events and life-history traits on diversification of unrelated but co-distributed species. Here, we examined the effects of the quaternary climate fluctuations and palaeomarine currents and present-day marine currents on the extant patterns of genetic diversity in the two most conspicuous mangrove species of the Neotropics. The black (Avicennia germinans, Avicenniaceae) and the red (Rhizophora mangle, Rhizophoraceae) mangroves have similar geographic ranges but are very distantly related and show striking differences on their life-history traits. We sampled 18 Atlantic and 26 Pacific locations for A. germinans (N = 292) and R. mangle (N = 422). We performed coalescence simulations using microsatellite diversity to test for evidence of population change associated with quaternary climate fluctuations. In addition, we examined whether patterns of genetic variation were consistent with the directions of major marine (historical and present day) currents in the region. Our demographic analysis was grounded within a phylogeographic framework provided by the sequence analysis of two chloroplasts and one flanking microsatellite region in a subsample of individuals. The two mangrove species shared similar biogeographic histories including: (1) strong genetic breaks between Atlantic and Pacific ocean basins associated with the final closure of the Central American Isthmus (CAI), (2) evidence for simultaneous population declines between the mid-Pleistocene and early Holocene, (3) asymmetric historical migration with higher gene flow from the Atlantic to the Pacific oceans following the direction of the palaeomarine current, and (4) contemporary gene flow between West Africa and South America following the major Atlantic Ocean currents. Despite the remarkable differences in life-history traits of mangrove species, which should have had a strong influence on seed

  9. Contrasting demographic history and gene flow patterns of two mangrove species on either side of the Central American Isthmus

    PubMed Central

    Cerón-Souza, Ivania; Gonzalez, Elena G; Schwarzbach, Andrea E; Salas-Leiva, Dayana E; Rivera-Ocasio, Elsie; Toro-Perea, Nelson; Bermingham, Eldredge; McMillan, W Owen

    2015-01-01

    Comparative phylogeography offers a unique opportunity to understand the interplay between past environmental events and life-history traits on diversification of unrelated but co-distributed species. Here, we examined the effects of the quaternary climate fluctuations and palaeomarine currents and present-day marine currents on the extant patterns of genetic diversity in the two most conspicuous mangrove species of the Neotropics. The black (Avicennia germinans, Avicenniaceae) and the red (Rhizophora mangle, Rhizophoraceae) mangroves have similar geographic ranges but are very distantly related and show striking differences on their life-history traits. We sampled 18 Atlantic and 26 Pacific locations for A. germinans (N = 292) and R. mangle (N = 422). We performed coalescence simulations using microsatellite diversity to test for evidence of population change associated with quaternary climate fluctuations. In addition, we examined whether patterns of genetic variation were consistent with the directions of major marine (historical and present day) currents in the region. Our demographic analysis was grounded within a phylogeographic framework provided by the sequence analysis of two chloroplasts and one flanking microsatellite region in a subsample of individuals. The two mangrove species shared similar biogeographic histories including: (1) strong genetic breaks between Atlantic and Pacific ocean basins associated with the final closure of the Central American Isthmus (CAI), (2) evidence for simultaneous population declines between the mid-Pleistocene and early Holocene, (3) asymmetric historical migration with higher gene flow from the Atlantic to the Pacific oceans following the direction of the palaeomarine current, and (4) contemporary gene flow between West Africa and South America following the major Atlantic Ocean currents. Despite the remarkable differences in life-history traits of mangrove species, which should have had a strong influence on seed

  10. Contrasting demographic history and gene flow patterns of two mangrove species on either side of the Central American Isthmus.

    PubMed

    Cerón-Souza, Ivania; Gonzalez, Elena G; Schwarzbach, Andrea E; Salas-Leiva, Dayana E; Rivera-Ocasio, Elsie; Toro-Perea, Nelson; Bermingham, Eldredge; McMillan, W Owen

    2015-08-01

    Comparative phylogeography offers a unique opportunity to understand the interplay between past environmental events and life-history traits on diversification of unrelated but co-distributed species. Here, we examined the effects of the quaternary climate fluctuations and palaeomarine currents and present-day marine currents on the extant patterns of genetic diversity in the two most conspicuous mangrove species of the Neotropics. The black (Avicennia germinans, Avicenniaceae) and the red (Rhizophora mangle, Rhizophoraceae) mangroves have similar geographic ranges but are very distantly related and show striking differences on their life-history traits. We sampled 18 Atlantic and 26 Pacific locations for A. germinans (N = 292) and R. mangle (N = 422). We performed coalescence simulations using microsatellite diversity to test for evidence of population change associated with quaternary climate fluctuations. In addition, we examined whether patterns of genetic variation were consistent with the directions of major marine (historical and present day) currents in the region. Our demographic analysis was grounded within a phylogeographic framework provided by the sequence analysis of two chloroplasts and one flanking microsatellite region in a subsample of individuals. The two mangrove species shared similar biogeographic histories including: (1) strong genetic breaks between Atlantic and Pacific ocean basins associated with the final closure of the Central American Isthmus (CAI), (2) evidence for simultaneous population declines between the mid-Pleistocene and early Holocene, (3) asymmetric historical migration with higher gene flow from the Atlantic to the Pacific oceans following the direction of the palaeomarine current, and (4) contemporary gene flow between West Africa and South America following the major Atlantic Ocean currents. Despite the remarkable differences in life-history traits of mangrove species, which should have had a strong influence on seed

  11. Contrasting recombination patterns and demographic histories of the plant pathogen Ralstonia solanacearum inferred from MLSA

    PubMed Central

    Wicker, Emmanuel; Lefeuvre, Pierre; de Cambiaire, Jean-Charles; Lemaire, Christophe; Poussier, Stéphane; Prior, Philippe

    2012-01-01

    We used multilocus sequence analysis (MLSA) on a worldwide collection of the plant pathogenic Ralstonia solanacearum (Betaproteobacteria) to retrace its complex evolutionary history. Using genetic imprints left during R. solanacearum evolution, we were able to delineate distinct evolutionary complex displaying contrasting dynamics. Among the phylotypes already described (I, IIA, IIB, III, IV), eight groups of strains with distinct evolutionary patterns, named clades, were identified. From our recombination analysis, we identified 21 recombination events that occurred within and across these lineages. Although appearing the most divergent and ancestral phylotype, phylotype IV was inferred as a gene donor for the majority of the recombination events that we detected. Whereas this phylotype apparently fuelled the species diversity, ongoing diversification was mainly detected within phylotype I, IIA and III. These three groups presented a recent expanding population structure, a high level of homologous recombination and evidences of long-distance migrations. Factors such as adaptation to a specific host or intense trading of infected crops may have promoted this diversification. Whether R. solanacearum lineages will eventually evolve in distinct species remains an open question. The intensification of cropping and increase of geographical dispersion may favour situations of phylotype sympatry and promote higher exchange of key factors for host adaptation from their common genetic pool. PMID:22094345

  12. Demographic history of speciation in a Senecio altitudinal hybrid zone on Mt. Etna.

    PubMed

    Filatov, Dmitry A; Osborne, Owen G; Papadopulos, Alexander S T

    2016-06-01

    Hybrid zones typically form as a result of species coming into secondary contact, but can also be established in situ as an ecotonal hybrid zone, a situation which has been reported far less frequently. An altitudinal hybrid zone on Mount Etna between two ragwort species (the low elevation Senecio chrysanthemifolius and high elevation S. aethnensis) could potentially represent either of these possibilities. However, a scenario of secondary contact vs. speciation with gene flow has not been explicitly tested. Here, we test these alternatives and demonstrate that the data do not support secondary contact. Furthermore, we report that the previous analyses of speciation history of these species were based on admixed populations, which has led to inflated estimates of ongoing, interspecific gene flow. Our new analyses, based on 'pure' S. aethnensis and S. chrysanthemifolius populations, reveal gene exchange of less than one effective migrant per generation, a level low enough to allow the species to accumulate neutral, genomewide differences. Overall, our results are consistent with a scenario of speciation with gene flow and a divergence time which coincides with the rise of Mt. Etna to altitudes above 2000 m (~150 KY). Further work to quantify the role of adaptation to contrasting environments of high and low altitudes will be needed to support the scenario of recent ecological speciation in this system. PMID:26994342

  13. Demographic history of Diadema antillarum, a keystone herbivore on Caribbean reefs.

    PubMed Central

    Lessios, H. A.; Garrido, M. J.; Kessing, B. D.

    2001-01-01

    The sea urchin Diadema antillarum was the most important herbivore on Caribbean reefs until 1983, when mass mortality reduced its populations by more than 97%. Knowledge of its past demography is essential to reconstruct reef ecology as it was before human impact, which has been implicated as having caused high pre-mortality Diadema abundance. To determine the history of its population size, we sequenced the ATPase 6 and 8 region of mitochondrial DNA from populations in the Caribbean and in the eastern Atlantic (which was not affected by the mass mortality), as well as from the eastern Pacific D. mexicanum. The Caribbean population harbours an order of magnitude more molecular diversity than those of the eastern Pacific or the eastern Atlantic and, despite the recent mass mortality, its DNA sequences bear the genetic signature of a previous population expansion. By estimating mutation rates from divergence between D. antillarum and D. mexicanum, that were separated at a known time by the Isthmus of Panama, and by using estimates of effective population size derived from mismatch distributions and a maximum likelihood coalescence algorithm, we date the expansion as having occurred no more recently than 100 000 years before the present. Thus, Diadema was abundant in the Caribbean long before humans could have affected ecological processes; the genetic data contain no evidence of a recent, anthropogenically caused, population increase. PMID:11703875

  14. Evolutionary and demographic history of the Californian scrub white oak species complex: an integrative approach.

    PubMed

    Ortego, Joaquín; Noguerales, Víctor; Gugger, Paul F; Sork, Victoria L

    2015-12-01

    Understanding the factors promoting species formation is a major task in evolutionary research. Here, we employ an integrative approach to study the evolutionary history of the Californian scrub white oak species complex (genus Quercus). To infer the relative importance of geographical isolation and ecological divergence in driving the speciation process, we (i) analysed inter- and intraspecific patterns of genetic differentiation and employed an approximate Bayesian computation (ABC) framework to evaluate different plausible scenarios of species divergence. In a second step, we (ii) linked the inferred divergence pathways with current and past species distribution models (SDMs) and (iii) tested for niche differentiation and phylogenetic niche conservatism across taxa. ABC analyses showed that the most plausible scenario is the one considering the divergence of two main lineages followed by a more recent pulse of speciation. Genotypic data in conjunction with SDMs and niche differentiation analyses support that different factors (geography vs. environment) and modes of speciation (parapatry, allopatry and maybe sympatry) have played a role in the divergence process within this complex. We found no significant relationship between genetic differentiation and niche overlap, which probably reflects niche lability and/or that multiple factors, have contributed to speciation. Our study shows that different mechanisms can drive divergence even among closely related taxa representing early stages of species formation and exemplifies the importance of adopting integrative approaches to get a better understanding of the speciation process. PMID:26547661

  15. Allelic disequilibrium and allele frequency distribution as a function of social and demographic history.

    PubMed Central

    Thompson, E A; Neel, J V

    1997-01-01

    Allelic disequilibrium between closely linked genes is a common observation in human populations and often gives rise to speculation concerning the role of selective forces. In a previous treatment, we have developed a population model of the expected distribution of rare variants (including private polymorphisms) in Amerindians and have argued that, because of the great expansion of Amerindian numbers with the advent of agriculture, most of these rare variants are of relatively recent origin. Many other populations have similar histories of striking recent expansions. In this treatment, we demonstrate that, in consequence of this fact, a high degree of linkage disequilibrium between two nonhomologous alleles <0.5 cM apart is the "normal" expectation, even in the absence of selection. This expectation is enhanced by the previous subdivision of human populations into relatively isolated tribes characterized by a high level of endogamy and inbreeding. We also demonstrate that the alleles associated with a recessive disease phenotype are expected to exist in a population in very variable frequencies: there is no need to postulate positive selection with respect to the more common disease-associated alleles for such entities as phenylketonuria or cystic fibrosis. PMID:8981963

  16. Demographic history of speciation in a Senecio altitudinal hybrid zone on Mt. Etna.

    PubMed

    Filatov, Dmitry A; Osborne, Owen G; Papadopulos, Alexander S T

    2016-06-01

    Hybrid zones typically form as a result of species coming into secondary contact, but can also be established in situ as an ecotonal hybrid zone, a situation which has been reported far less frequently. An altitudinal hybrid zone on Mount Etna between two ragwort species (the low elevation Senecio chrysanthemifolius and high elevation S. aethnensis) could potentially represent either of these possibilities. However, a scenario of secondary contact vs. speciation with gene flow has not been explicitly tested. Here, we test these alternatives and demonstrate that the data do not support secondary contact. Furthermore, we report that the previous analyses of speciation history of these species were based on admixed populations, which has led to inflated estimates of ongoing, interspecific gene flow. Our new analyses, based on 'pure' S. aethnensis and S. chrysanthemifolius populations, reveal gene exchange of less than one effective migrant per generation, a level low enough to allow the species to accumulate neutral, genomewide differences. Overall, our results are consistent with a scenario of speciation with gene flow and a divergence time which coincides with the rise of Mt. Etna to altitudes above 2000 m (~150 KY). Further work to quantify the role of adaptation to contrasting environments of high and low altitudes will be needed to support the scenario of recent ecological speciation in this system.

  17. Population Genomic Analysis Reveals a Rich Speciation and Demographic History of Orang-utans (Pongo pygmaeus and Pongo abelii)

    PubMed Central

    Ma, Xin; Kelley, Joanna L.; Eilertson, Kirsten; Musharoff, Shaila; Degenhardt, Jeremiah D.; Martins, André L.; Vinar, Tomas; Kosiol, Carolin; Siepel, Adam; Gutenkunst, Ryan N.; Bustamante, Carlos D.

    2013-01-01

    To gain insights into evolutionary forces that have shaped the history of Bornean and Sumatran populations of orang-utans, we compare patterns of variation across more than 11 million single nucleotide polymorphisms found by previous mitochondrial and autosomal genome sequencing of 10 wild-caught orang-utans. Our analysis of the mitochondrial data yields a far more ancient split time between the two populations (∼3.4 million years ago) than estimates based on autosomal data (0.4 million years ago), suggesting a complex speciation process with moderate levels of primarily male migration. We find that the distribution of selection coefficients consistent with the observed frequency spectrum of autosomal non-synonymous polymorphisms in orang-utans is similar to the distribution in humans. Our analysis indicates that 35% of genes have evolved under detectable negative selection. Overall, our findings suggest that purifying natural selection, genetic drift, and a complex demographic history are the dominant drivers of genome evolution for the two orang-utan populations. PMID:24194868

  18. The contribution of parental smoking history and socio-demographic factors to the smoking behavior of Israeli women.

    PubMed

    Segal-Engelchin, Dorit; Friedmann, Enav; Cwikel, Julie G

    2014-01-01

    This study examined the interplay between sociodemographic factors and parental smoking history in shaping the smoking behavior of Israeli women (N = 302). The study was conducted in the Negev region, which is characterized by a high proportion of immigrants and high percentage of low socioeconomic and educational groups. The specific objectives of this study were to examine: (1) The prevalence and characteristics of women smokers, ex-smokers and never-smokers; and (2) the contribution of education and parent smoking history to women's current smoking. Low levels of education, being Israeli born or veteran immigrants of European-American origin significantly increased the risk of smoking, whereas an orthodox lifestyle and new immigrant status significantly reduced the likelihood of smoking. Occasional smokers reported significantly higher primary care utilization than never smokers. A significant relationship between smoking and pain, gynecological symptoms and depression was found. Results indicate that childhood exposure to maternal smoking was a significant risk factor for smoking, whereas paternal past smoking negatively affects smoking in women. Also, results show that parental educational level affects women's smoking behavior indirectly by influencing their own educational attainment, which in turn is negatively associated with the likelihood of smoking. Mothers with higher education were more likely to smoke, an effect that was reversed for their daughters. Our results demonstrate how demographic, parental and lifestyle factors affect women's smoking in a multi-ethnic society and highlight the need to examine both generational and intergenerational effects.

  19. Comparative phylogeography and demographic history of European shads (Alosa alosa and A. fallax) inferred from mitochondrial DNA

    PubMed Central

    2012-01-01

    Mediterranean to the Atlantic was detected but not in the opposite direction, with colonization of the North Atlantic probably occurring after last glacial maximum. Conclusion The similar haplotype network topologies between the two species support a common intraspecific history of isolation. Despite these similarities, A. alosa and A. fallax have clearly responded differently to the hydrological dynamics of the Pleistocene, as reflected in their distinct demographic histories. As the species additionally occupy different ecological niches it should not be surprising that they differ in resilience to natural or human-mediated climatic changes. For A. fallax, it is further clear that its demographic response to large-scale hydrological events is not synchronized between the Atlantic and Mediterranean basins. These regional and species-specific differences should be incorporated into future predictive modeling of biological response to climate change as well as current management concepts. PMID:23020523

  20. Demographic history, genetic structure and gene flow in a steppe-associated raptor species

    PubMed Central

    2011-01-01

    Background Environmental preferences and past climatic changes may determine the length of time during which a species range has contracted or expanded from refugia, thereby influencing levels of genetic diversification. Connectivity among populations of steppe-associated taxa might have been maximal during the long glacial periods, and interrupted only during the shorter interglacial phases, potentially resulting in low levels of genetic differentiation among populations. We investigated this hypothesis by exploring patterns of genetic diversity, past demography and gene flow in a raptor species characteristic of steppes, the Montagu's harrier (Circus pygargus), using mitochondrial DNA data from 13 breeding populations and two wintering populations. Results Consistent with our hypothesis, Montagu's harrier has relatively low genetic variation at the mitochondrial DNA. The highest levels of genetic diversity were found in coastal Spain, France and central Asia. These areas, which were open landscapes during the Holocene, may have acted as refugia when most of the European continent was covered by forests. We found significant genetic differentiation between two population groups, at the SW and NE parts of the species' range. Two events of past population growth were detected, and occurred ca. 7500-5500 and ca. 3500-1000 years BP in the SW and NE part of the range respectively. These events were likely associated with vegetation shifts caused by climate and human-induced changes during the Holocene. Conclusions The relative genetic homogeneity observed across populations of this steppe raptor may be explained by a short isolation time, relatively recent population expansions and a relaxed philopatry. We highlight the importance of considering the consequence of isolation and colonization processes in order to better understand the evolutionary history of steppe species. PMID:22093489

  1. Population demographics and life history of the round hickorynut (Obovaria subrotunda) in the Duck River, Tennessee

    USGS Publications Warehouse

    Ehlo, Chase A.; Layzer, James B.

    2014-01-01

    Population characteristics and life history aspects of healthy mussel populations are poorly understood. The reproductive cycle, age and growth, and population structure of Obovaria subrotunda were examined at four sites in the middle Duck River, Tennessee. Obovaria subrotunda was confirmed to be a bradytictic species, spawning in the late summer and holding glochidia in the gills for 11 mo until the following summer. Fecundity was positively related to mussel length (R2  =  0.75) and ranged from 7122 to 76,584 glochidia. Fourteen species of fish found in the Duck River, in the families Percidae, Cyprinidae, and Cottidae, were infested with glochidia in the laboratory to examine potential hosts. Juveniles transformed onEtheostoma blennioides (greenside darter), E. obama (spangled darter), E. flabellare (fantail darter), and Cottus carolinae (banded sculpin). Analyses of shell thin-sections indicated that males grew faster and obtained a larger size than females. Individuals live to at least 14 y old. Females became sexually mature at age one. Four sites were quantitatively sampled using a systematic design with three random starts. The observed ratio of adult males to females (0.9∶1) did not differ significantly from 1∶1. Results of the quantitative sampling showed an increase in density compared to earlier studies and a high proportion of 1 to 5 y old O. subrotunda.

  2. Demographic patterns of Ferocactus cylindraceus in relation to substrate age and grazing history

    USGS Publications Warehouse

    Bowers, Janice E.

    1997-01-01

    Three subpopulations of Ferocactus cylindraceus, a short-columnar cactus of the Sonoran and Mojave deserts, were sampled in Grand Canyon, Arizona, USA, at sites representing a range of substrate ages and different grazing histories. Age-height relations were determined from annual growth, then used to estimate probable year of establishment for each cohort. Eight years between 1944 and 1992 were especially favorable for establishment. Six of these 8 years coincided with El Nino-Southern Oscillation conditions, indicating that as for many woody plants in arid regions, somewhat unusual climatic conditions are necessary if populations are to replace themselves. Comparison of age structures showed that established and developing populations have somewhat different dynamics in that the rate of population increase was slowest on the youngest terrace. On the ancient terraces, about half the plants were less than 25 years old. Plants older than 40 years were few; however the oldest plants in the study (about 49 years) grew on the ancient terraces. On the recent terrace, 76% of the subpopulation was 25 years or younger, and the oldest living plant was about 36 years of age. The age structures of subpopulations on grazed and ungrazed sites also differed markedly. On ungrazed sites, subpopulations were more or less at equilibrium, with enough young plants to replace old ones as they died. In contrast, the subpopulation on the grazed site was in a state of marked disequilibrium. Grazing before 1981 largely extirpated a palatable subshrub that was probably an important nurse plant. Until the shrub population at Indian Canyon recovers from decades of burro grazing, a rebound in E cylindraceus establishment is not to be expected.

  3. Recent demographic history and present fine-scale structure in the Northwest Atlantic leatherback (Dermochelys coriacea) turtle population.

    PubMed

    Molfetti, Erica; Vilaça, Sibelle Torres; Georges, Jean-Yves; Plot, Virginie; Delcroix, Eric; Le Scao, Rozen; Lavergne, Anne; Barrioz, Sébastien; dos Santos, Fabrício Rodrigues; de Thoisy, Benoît

    2013-01-01

    The leatherback turtle Dermochelys coriacea is the most widely distributed sea turtle species in the world. It exhibits complex life traits: female homing and migration, migrations of juveniles and males that remain poorly known, and a strong climatic influence on resources, breeding success and sex-ratio. It is consequently challenging to understand population dynamics. Leatherbacks are critically endangered, yet the group from the Northwest Atlantic is currently considered to be under lower risk than other populations while hosting some of the largest rookeries. Here, we investigated the genetic diversity and the demographic history of contrasted rookeries from this group, namely two large nesting populations in French Guiana, and a smaller one in the French West Indies. We used 10 microsatellite loci, of which four are newly isolated, and mitochondrial DNA sequences of the control region and cytochrome b. Both mitochondrial and nuclear markers revealed that the Northwest Atlantic stock of leatherbacks derives from a single ancestral origin, but show current genetic structuration at the scale of nesting sites, with the maintenance of migrants amongst rookeries. Low nuclear genetic diversities are related to founder effects that followed consequent bottlenecks during the late Pleistocene/Holocene. Most probably in response to climatic oscillations, with a possible influence of early human hunting, female effective population sizes collapsed from 2 million to 200. Evidence of founder effects and high numbers of migrants make it possible to reconsider the population dynamics of the species, formerly considered as a metapopulation model: we propose a more relaxed island model, which we expect to be a key element in the currently observed recovering of populations. Although these Northwest Atlantic rookeries should be considered as a single evolutionary unit, we stress that local conservation efforts remain necessary since each nesting site hosts part of the genetic

  4. Gene flow and demographic history of the mangrove crab Neosarmatium meinerti: A case study from the western Indian Ocean

    NASA Astrophysics Data System (ADS)

    Ragionieri, Lapo; Cannicci, Stefano; Schubart, Christoph D.; Fratini, Sara

    2010-01-01

    Most marine organisms are characterized by at least one planktonic phase during their life history, potentially allowing interconnection of populations separated by several hundred kilometers. For many years, the idea that marine species are genetically homogenous throughout their range of distribution, due to passive larval transport, has been a paradigm. Nowadays, a growing number of studies underline the existence of boundaries in the marine realm and highlight how larval dispersal is a complex process depending on biotic as well as abiotic factors. Marine fragmented habitats, such as atolls, mangroves and estuaries, are optimal systems for investigating the marine dispersion process under a metapopulation approach, since populations can be geographically defined a priori as opposed to those occupying open marine environments. Within this frame, the present paper investigates the population genetic structure and the demographic history of the mangrove crab Neosarmatium meinerti within the western Indian Ocean by partial sequences of the mitochondrial DNA cytochrome oxidase subunit I. A total of 167 specimens were sampled from six mangrove sites distributed along the East African coast, from Kenya to South Africa, also including a mangrove forest located on Mahé Island, Seychelles. A sharp genetic break between the mainland and the Seychelles is recorded, revealing the existence of two historically distinct groups that can be defined as independent evolutionary units. Gene flow along the East African coast appears to be high enough to form a single metapopulation, probably by means of stepping stone populations. Otherwise, this mainland metapopulation is currently under expansion through a gradual moving front from the subtropical toward the equatorial populations.

  5. Recent Demographic History and Present Fine-Scale Structure in the Northwest Atlantic Leatherback (Dermochelys coriacea) Turtle Population

    PubMed Central

    Molfetti, Érica; Torres Vilaça, Sibelle; Georges, Jean-Yves; Plot, Virginie; Delcroix, Eric; Le Scao, Rozen; Lavergne, Anne; Barrioz, Sébastien; dos Santos, Fabrício Rodrigues; de Thoisy, Benoît

    2013-01-01

    The leatherback turtle Dermochelys coriacea is the most widely distributed sea turtle species in the world. It exhibits complex life traits: female homing and migration, migrations of juveniles and males that remain poorly known, and a strong climatic influence on resources, breeding success and sex-ratio. It is consequently challenging to understand population dynamics. Leatherbacks are critically endangered, yet the group from the Northwest Atlantic is currently considered to be under lower risk than other populations while hosting some of the largest rookeries. Here, we investigated the genetic diversity and the demographic history of contrasted rookeries from this group, namely two large nesting populations in French Guiana, and a smaller one in the French West Indies. We used 10 microsatellite loci, of which four are newly isolated, and mitochondrial DNA sequences of the control region and cytochrome b. Both mitochondrial and nuclear markers revealed that the Northwest Atlantic stock of leatherbacks derives from a single ancestral origin, but show current genetic structuration at the scale of nesting sites, with the maintenance of migrants amongst rookeries. Low nuclear genetic diversities are related to founder effects that followed consequent bottlenecks during the late Pleistocene/Holocene. Most probably in response to climatic oscillations, with a possible influence of early human hunting, female effective population sizes collapsed from 2 million to 200. Evidence of founder effects and high numbers of migrants make it possible to reconsider the population dynamics of the species, formerly considered as a metapopulation model: we propose a more relaxed island model, which we expect to be a key element in the currently observed recovering of populations. Although these Northwest Atlantic rookeries should be considered as a single evolutionary unit, we stress that local conservation efforts remain necessary since each nesting site hosts part of the genetic

  6. Recent demographic history and present fine-scale structure in the Northwest Atlantic leatherback (Dermochelys coriacea) turtle population.

    PubMed

    Molfetti, Erica; Vilaça, Sibelle Torres; Georges, Jean-Yves; Plot, Virginie; Delcroix, Eric; Le Scao, Rozen; Lavergne, Anne; Barrioz, Sébastien; dos Santos, Fabrício Rodrigues; de Thoisy, Benoît

    2013-01-01

    The leatherback turtle Dermochelys coriacea is the most widely distributed sea turtle species in the world. It exhibits complex life traits: female homing and migration, migrations of juveniles and males that remain poorly known, and a strong climatic influence on resources, breeding success and sex-ratio. It is consequently challenging to understand population dynamics. Leatherbacks are critically endangered, yet the group from the Northwest Atlantic is currently considered to be under lower risk than other populations while hosting some of the largest rookeries. Here, we investigated the genetic diversity and the demographic history of contrasted rookeries from this group, namely two large nesting populations in French Guiana, and a smaller one in the French West Indies. We used 10 microsatellite loci, of which four are newly isolated, and mitochondrial DNA sequences of the control region and cytochrome b. Both mitochondrial and nuclear markers revealed that the Northwest Atlantic stock of leatherbacks derives from a single ancestral origin, but show current genetic structuration at the scale of nesting sites, with the maintenance of migrants amongst rookeries. Low nuclear genetic diversities are related to founder effects that followed consequent bottlenecks during the late Pleistocene/Holocene. Most probably in response to climatic oscillations, with a possible influence of early human hunting, female effective population sizes collapsed from 2 million to 200. Evidence of founder effects and high numbers of migrants make it possible to reconsider the population dynamics of the species, formerly considered as a metapopulation model: we propose a more relaxed island model, which we expect to be a key element in the currently observed recovering of populations. Although these Northwest Atlantic rookeries should be considered as a single evolutionary unit, we stress that local conservation efforts remain necessary since each nesting site hosts part of the genetic

  7. Evolutionary origin and demographic history of an ancient conifer (Juniperus microsperma) in the Qinghai-Tibetan Plateau.

    PubMed

    Shang, Hui-Ying; Li, Zhong-Hu; Dong, Miao; Adams, Robert P; Miehe, Georg; Opgenoorth, Lars; Mao, Kang-Shan

    2015-05-15

    All Qinghai-Tibetan Plateau (QTP) endemic species are assumed to have originated recently, although very rare species most likely diverged early. These ancient species provide an excellent model to examine the origin and evolution of QTP endemic plants in response to the QTP uplifts and the climate changes that followed in this high altitude region. In this study, we examined these hypotheses by employing sequence variation from multiple nuclear and chloroplast DNA of 239 individuals of Juniperus microsperma and its five congeners. Both phylogenetic and population genetic analyses revealed that J. microsperma diverged from its sister clade comprising two species with long isolation around the Early Miocene, which corresponds to early QTP uplift. Demographic modeling and coalescent tests suggest that J. microsperma experienced an obvious bottleneck event during the Quaternary when the global climate greatly oscillated. The results presented here support the hypotheses that the QTP uplifts and Quaternary climate changes played important roles in shaping the evolutionary history of this rare juniper.

  8. Speciation, population structure, and demographic history of the Mojave Fringe-toed Lizard (Uma scoparia), a species of conservation concern

    PubMed Central

    Gottscho, Andrew D; Marks, Sharyn B; Jennings, W Bryan

    2014-01-01

    The North American deserts were impacted by both Neogene plate tectonics and Quaternary climatic fluctuations, yet it remains unclear how these events influenced speciation in this region. We tested published hypotheses regarding the timing and mode of speciation, population structure, and demographic history of the Mojave Fringe-toed Lizard (Uma scoparia), a sand dune specialist endemic to the Mojave Desert of California and Arizona. We sampled 109 individual lizards representing 22 insular dune localities, obtained DNA sequences for 14 nuclear loci, and found that U. scoparia has low genetic diversity relative to the U. notata species complex, comparable to that of chimpanzees and southern elephant seals. Analyses of genotypes using Bayesian clustering algorithms did not identify discrete populations within U. scoparia. Using isolation-with-migration (IM) models and a novel coalescent-based hypothesis testing approach, we estimated that U. scoparia diverged from U. notata in the Pleistocene epoch. The likelihood ratio test and the Akaike Information Criterion consistently rejected nested speciation models that included parameters for migration and population growth of U. scoparia. We reject the Neogene vicariance hypothesis for the speciation of U. scoparia and define this species as a single evolutionarily significant unit for conservation purposes. PMID:25360285

  9. Speciation, population structure, and demographic history of the Mojave Fringe-toed Lizard (Uma scoparia), a species of conservation concern.

    PubMed

    Gottscho, Andrew D; Marks, Sharyn B; Jennings, W Bryan

    2014-06-01

    The North American deserts were impacted by both Neogene plate tectonics and Quaternary climatic fluctuations, yet it remains unclear how these events influenced speciation in this region. We tested published hypotheses regarding the timing and mode of speciation, population structure, and demographic history of the Mojave Fringe-toed Lizard (Uma scoparia), a sand dune specialist endemic to the Mojave Desert of California and Arizona. We sampled 109 individual lizards representing 22 insular dune localities, obtained DNA sequences for 14 nuclear loci, and found that U. scoparia has low genetic diversity relative to the U. notata species complex, comparable to that of chimpanzees and southern elephant seals. Analyses of genotypes using Bayesian clustering algorithms did not identify discrete populations within U. scoparia. Using isolation-with-migration (IM) models and a novel coalescent-based hypothesis testing approach, we estimated that U. scoparia diverged from U. notata in the Pleistocene epoch. The likelihood ratio test and the Akaike Information Criterion consistently rejected nested speciation models that included parameters for migration and population growth of U. scoparia. We reject the Neogene vicariance hypothesis for the speciation of U. scoparia and define this species as a single evolutionarily significant unit for conservation purposes. PMID:25360285

  10. Low Genetic Diversity in Wide-Spread Eurasian Liver Fluke Opisthorchis felineus Suggests Special Demographic History of This Trematode Species

    PubMed Central

    Brusentsov, Ilja I.; Katokhin, Alexey V.; Brusentsova, Irina V.; Shekhovtsov, Sergei V.; Borovikov, Sergei N.; Goncharenko, Grigoriy G.; Lider, Lyudmila A.; Romashov, Boris V.; Rusinek, Olga T.; Shibitov, Samat K.; Suleymanov, Marat M.; Yevtushenko, Andrey V.; Mordvinov, Viatcheslav A.

    2013-01-01

    Opisthorchis felineus or Siberian liver fluke is a trematode parasite (Opisthorchiidae) that infects the hepato-biliary system of humans and other mammals. Despite its public health significance, this wide-spread Eurasian species is one of the most poorly studied human liver flukes and nothing is known about its population genetic structure and demographic history. In this paper, we attempt to fill this gap for the first time and to explore the genetic diversity in O. felineus populations from Eastern Europe (Ukraine, European part of Russia), Northern Asia (Siberia) and Central Asia (Northern Kazakhstan). Analysis of marker DNA fragments from O. felineus mitochondrial cytochrome c oxidase subunit 1 and 3 (cox1, cox3) and nuclear rDNA internal transcribed spacer 1 (ITS1) sequences revealed that genetic diversity is very low across the large geographic range of this species. Microevolutionary processes in populations of trematodes may well be influenced by their peculiar biology. Nevertheless, we suggest that lack of population genetics structure observed in O. felineus can be primarily explained by the Pleistocene glacial events and subsequent sudden population growth from a very limited group of founders. Rapid range expansion of O. felineus through Asian and European territories after severe bottleneck points to a high dispersal potential of this trematode species. PMID:23634228

  11. Low genetic diversity in wide-spread Eurasian liver fluke Opisthorchis felineus suggests special demographic history of this trematode species.

    PubMed

    Brusentsov, Ilja I; Katokhin, Alexey V; Brusentsova, Irina V; Shekhovtsov, Sergei V; Borovikov, Sergei N; Goncharenko, Grigoriy G; Lider, Lyudmila A; Romashov, Boris V; Rusinek, Olga T; Shibitov, Samat K; Suleymanov, Marat M; Yevtushenko, Andrey V; Mordvinov, Viatcheslav A

    2013-01-01

    Opisthorchis felineus or Siberian liver fluke is a trematode parasite (Opisthorchiidae) that infects the hepato-biliary system of humans and other mammals. Despite its public health significance, this wide-spread Eurasian species is one of the most poorly studied human liver flukes and nothing is known about its population genetic structure and demographic history. In this paper, we attempt to fill this gap for the first time and to explore the genetic diversity in O. felineus populations from Eastern Europe (Ukraine, European part of Russia), Northern Asia (Siberia) and Central Asia (Northern Kazakhstan). Analysis of marker DNA fragments from O. felineus mitochondrial cytochrome c oxidase subunit 1 and 3 (cox1, cox3) and nuclear rDNA internal transcribed spacer 1 (ITS1) sequences revealed that genetic diversity is very low across the large geographic range of this species. Microevolutionary processes in populations of trematodes may well be influenced by their peculiar biology. Nevertheless, we suggest that lack of population genetics structure observed in O. felineus can be primarily explained by the Pleistocene glacial events and subsequent sudden population growth from a very limited group of founders. Rapid range expansion of O. felineus through Asian and European territories after severe bottleneck points to a high dispersal potential of this trematode species. PMID:23634228

  12. Genetic Structure and Demographic History Should Inform Conservation: Chinese Cobras Currently Treated as Homogenous Show Population Divergence

    PubMed Central

    Lin, Long-Hui; Qu, Yan-Fu; Li, Hong; Zhou, Kai-Ya; Ji, Xiang

    2012-01-01

    An understanding of population structure and genetic diversity is crucial for wildlife conservation and for determining the integrity of wildlife populations. The vulnerable Chinese cobra (Naja atra) has a distribution from the mouth of the Yangtze River down to northern Vietnam and Laos, within which several large mountain ranges and water bodies may influence population structure. We combined 12 microsatellite loci and 1117 bp of the mitochondrial cytochrome b gene to explore genetic structure and demographic history in this species, using 269 individuals from various localities in Mainland China and Vietnam. High levels of genetic variation were identified for both mtDNA and microsatellites. mtDNA data revealed two main (Vietnam + southern China + southwestern China; eastern + southeastern China) and one minor (comprising only two individuals from the westernmost site) clades. Microsatellite data divided the eastern + southeastern China clade further into two genetic clusters, which include individuals from the eastern and southeastern regions, respectively. The Luoxiao and Nanling Mountains may be important barriers affecting the diversification of lineages. In the haplotype network of cytchrome b, many haplotypes were represented within a “star” cluster and this and other tests suggest recent expansion. However, microsatellite analyses did not yield strong evidence for a recent bottleneck for any population or genetic cluster. The three main clusters identified here should be considered as independent management units for conservation purposes. The release of Chinese cobras into the wild should cease unless their origin can be determined, and this will avoid problems arising from unnatural homogenization. PMID:22558439

  13. Evolutionary origin and demographic history of an ancient conifer (Juniperus microsperma) in the Qinghai-Tibetan Plateau

    PubMed Central

    Shang, Hui-Ying; Li, Zhong-Hu; Dong, Miao; Adams, Robert P.; Miehe, Georg; Opgenoorth, Lars; Mao, Kang-Shan

    2015-01-01

    All Qinghai-Tibetan Plateau (QTP) endemic species are assumed to have originated recently, although very rare species most likely diverged early. These ancient species provide an excellent model to examine the origin and evolution of QTP endemic plants in response to the QTP uplifts and the climate changes that followed in this high altitude region. In this study, we examined these hypotheses by employing sequence variation from multiple nuclear and chloroplast DNA of 239 individuals of Juniperus microsperma and its five congeners. Both phylogenetic and population genetic analyses revealed that J. microsperma diverged from its sister clade comprising two species with long isolation around the Early Miocene, which corresponds to early QTP uplift. Demographic modeling and coalescent tests suggest that J. microsperma experienced an obvious bottleneck event during the Quaternary when the global climate greatly oscillated. The results presented here support the hypotheses that the QTP uplifts and Quaternary climate changes played important roles in shaping the evolutionary history of this rare juniper. PMID:25977142

  14. Joint palaeoclimate reconstruction from pollen data via forward models and climate histories

    NASA Astrophysics Data System (ADS)

    Parnell, Andrew C.; Haslett, John; Sweeney, James; Doan, Thinh K.; Allen, Judy R. M.; Huntley, Brian

    2016-11-01

    We present a method and software for reconstructing palaeoclimate from pollen data with a focus on accounting for and reducing uncertainty. The tools we use include: forward models, which enable us to account for the data generating process and hence the complex relationship between pollen and climate; joint inference, which reduces uncertainty by borrowing strength between aspects of climate and slices of the core; and dynamic climate histories, which allow for a far richer gamut of inferential possibilities. Through a Monte Carlo approach we generate numerous equally probable joint climate histories, each of which is represented by a sequence of values of three climate dimensions in discrete time, i.e. a multivariate time series. All histories are consistent with the uncertainties in the forward model and the natural temporal variability in climate. Once generated, these histories can provide most probable climate estimates with uncertainty intervals. This is particularly important as attention moves to the dynamics of past climate changes. For example, such methods allow us to identify, with realistic uncertainty, the past century that exhibited the greatest warming. We illustrate our method with two data sets: Laguna de la Roya, with a radiocarbon dated chronology and hence timing uncertainty; and Lago Grande di Monticchio, which contains laminated sediment and extends back to the penultimate glacial stage. The procedure is made available via an open source R package, Bclim, for which we provide code and instructions.

  15. The Impact of Demographic Changes on Social Programs. Joint Economic Committee, Ninety-Seventh Congress, Second Session.

    ERIC Educational Resources Information Center

    Joint Economic Committee, Washington, DC.

    The social policy implications of demographic trends are examined, to help policy makers anticipate future needs for services with greater accuracy. Crises such as energy needs and social security financing illustrate the need for greater recognition of the time dimension of public policy. Many of our most difficult problems, if they are to be…

  16. Reconciling deep calibration and demographic history: bayesian inference of post glacial colonization patterns in Carcinus aestuarii (Nardo, 1847) and C. maenas (Linnaeus, 1758).

    PubMed

    Marino, Ilaria A M; Pujolar, Jose Martin; Zane, Lorenzo

    2011-01-01

    A precise inference of past demographic histories including dating of demographic events using bayesian methods can only be achieved with the use of appropriate molecular rates and evolutionary models. Using a set of 596 mitochondrial cytochrome c oxidase I (COI) sequences of two sister species of European green crabs of the genus Carcinus (C. maenas and C. aestuarii), our study shows how chronologies of past evolutionary events change significantly with the application of revised molecular rates that incorporate biogeographic events for calibration and appropriate demographic priors. A clear signal of demographic expansion was found for both species, dated between 10,000 and 20,000 years ago, which places the expansions events in a time frame following the Last Glacial Maximum (LGM). In the case of C. aestuarii, a population expansion was only inferred for the Adriatic-Ionian, suggestive of a colonization event following the flooding of the Adriatic Sea (18,000 years ago). For C. maenas, the demographic expansion inferred for the continental populations of West and North Europe might result from a northward recolonization from a southern refugium when the ice sheet retreated after the LGM. Collectively, our results highlight the importance of using adequate calibrations and demographic priors in order to avoid considerable overestimates of evolutionary time scales. PMID:22164307

  17. Comparative demography of an epiphytic lichen: support for general life history patterns and solutions to common problems in demographic parameter estimation.

    PubMed

    Shriver, Robert K; Cutler, Kerry; Doak, Daniel F

    2012-09-01

    Lichens are major components in many terrestrial ecosystems, yet their population ecology is at best only poorly understood. Few studies have fully quantified the life history or demographic patterns of any lichen, with particularly little attention to epiphytic species. We conducted a 6-year demographic study of Vulpicida pinastri, an epiphytic foliose lichen, in south-central Alaska. After testing multiple size-structured functions to describe patterns in each V. pinastri demographic rate, we used the resulting estimates to construct a stochastic demographic model for the species. This model development led us to propose solutions to two general problems in construction of demographic models for many taxa: how to simply but accurately characterize highly skewed growth rates, and how to estimate recruitment rates that are exceptionally difficult to directly observe. Our results show that V. pinastri has rapid and variable growth and, for small individuals, low and variable survival, but that these traits are coupled with considerable longevity (e.g., >50 years mean future life span for a 4-cm(2) thallus) and little deviation of the stochastic population growth rate from the deterministic expectation. Comparisons of the demographic patterns we found with those of other lichen studies suggest that their relatively simple architecture may allow clearer generalities about growth patterns for lichens than for other taxa, and that the expected pattern of faster growth rates for epiphytic species is substantiated.

  18. Reconciling Deep Calibration and Demographic History: Bayesian Inference of Post Glacial Colonization Patterns in Carcinus aestuarii (Nardo, 1847) and C. maenas (Linnaeus, 1758)

    PubMed Central

    Marino, Ilaria A. M.; Pujolar, Jose Martin; Zane, Lorenzo

    2011-01-01

    A precise inference of past demographic histories including dating of demographic events using Bayesian methods can only be achieved with the use of appropriate molecular rates and evolutionary models. Using a set of 596 mitochondrial cytochrome c oxidase I (COI) sequences of two sister species of European green crabs of the genus Carcinus (C. maenas and C. aestuarii), our study shows how chronologies of past evolutionary events change significantly with the application of revised molecular rates that incorporate biogeographic events for calibration and appropriate demographic priors. A clear signal of demographic expansion was found for both species, dated between 10,000 and 20,000 years ago, which places the expansions events in a time frame following the Last Glacial Maximum (LGM). In the case of C. aestuarii, a population expansion was only inferred for the Adriatic-Ionian, suggestive of a colonization event following the flooding of the Adriatic Sea (18,000 years ago). For C. maenas, the demographic expansion inferred for the continental populations of West and North Europe might result from a northward recolonization from a southern refugium when the ice sheet retreated after the LGM. Collectively, our results highlight the importance of using adequate calibrations and demographic priors in order to avoid considerable overestimates of evolutionary time scales. PMID:22164307

  19. Reconstructing the Demographic History of the Human Lineage Using Whole-Genome Sequences from Human and Three Great Apes

    PubMed Central

    Hara, Yuichiro; Imanishi, Tadashi; Satta, Yoko

    2012-01-01

    The demographic history of human would provide helpful information for identifying the evolutionary events that shaped the humanity but remains controversial even in the genomic era. To settle the controversies, we inferred the speciation times (T) and ancestral population sizes (N) in the lineage leading to human and great apes based on whole-genome alignment. A coalescence simulation determined the sizes of alignment blocks and intervals between them required to obtain recombination-free blocks with a high frequency. This simulation revealed that the size of the block strongly affects the parameter inference, indicating that recombination is an important factor for achieving optimum parameter inference. From the whole genome alignments (1.9 giga-bases) of human (H), chimpanzee (C), gorilla (G), and orangutan, 100-bp alignment blocks separated by ≥5-kb intervals were sampled and subjected to estimate τ = μT and θ = 4μgN using the Markov chain Monte Carlo method, where μ is the mutation rate and g is the generation time. Although the estimated τHC differed across chromosomes, τHC and τHCG were strongly correlated across chromosomes, indicating that variation in τ is subject to variation in μ, rather than T, and thus, all chromosomes share a single speciation time. Subsequently, we estimated Ts of the human lineage from chimpanzee, gorilla, and orangutan to be 6.0–7.6, 7.6–9.7, and 15–19 Ma, respectively, assuming variable μ across lineages and chromosomes. These speciation times were consistent with the fossil records. We conclude that the speciation times in our recombination-free analysis would be conclusive and the speciation between human and chimpanzee was a single event. PMID:22975719

  20. The impact of selection, gene flow and demographic history on heterogeneous genomic divergence: three-spine sticklebacks in divergent environments.

    PubMed

    Ferchaud, Anne-Laure; Hansen, Michael M

    2016-01-01

    Heterogeneous genomic divergence between populations may reflect selection, but should also be seen in conjunction with gene flow and drift, particularly population bottlenecks. Marine and freshwater three-spine stickleback (Gasterosteus aculeatus) populations often exhibit different lateral armour plate morphs. Moreover, strikingly parallel genomic footprints across different marine-freshwater population pairs are interpreted as parallel evolution and gene reuse. Nevertheless, in some geographic regions like the North Sea and Baltic Sea, different patterns are observed. Freshwater populations in coastal regions are often dominated by marine morphs, suggesting that gene flow overwhelms selection, and genomic parallelism may also be less pronounced. We used RAD sequencing for analysing 28 888 SNPs in two marine and seven freshwater populations in Denmark, Europe. Freshwater populations represented a variety of environments: river populations accessible to gene flow from marine sticklebacks and large and small isolated lakes with and without fish predators. Sticklebacks in an accessible river environment showed minimal morphological and genomewide divergence from marine populations, supporting the hypothesis of gene flow overriding selection. Allele frequency spectra suggested bottlenecks in all freshwater populations, and particularly two small lake populations. However, genomic footprints ascribed to selection could nevertheless be identified. No genomic regions were consistent freshwater-marine outliers, and parallelism was much lower than in other comparable studies. Two genomic regions previously described to be under divergent selection in freshwater and marine populations were outliers between different freshwater populations. We ascribe these patterns to stronger environmental heterogeneity among freshwater populations in our study as compared to most other studies, although the demographic history involving bottlenecks should also be considered in the

  1. Divorcing the Late Upper Palaeolithic demographic histories of mtDNA haplogroups M1 and U6 in Africa

    PubMed Central

    2012-01-01

    Background A Southwest Asian origin and dispersal to North Africa in the Early Upper Palaeolithic era has been inferred in previous studies for mtDNA haplogroups M1 and U6. Both haplogroups have been proposed to show similar geographic patterns and shared demographic histories. Results We report here 24 M1 and 33 U6 new complete mtDNA sequences that allow us to refine the existing phylogeny of these haplogroups. The resulting phylogenetic information was used to genotype a further 131 M1 and 91 U6 samples to determine the geographic spread of their sub-clades. No southwest Asian specific clades for M1 or U6 were discovered. U6 and M1 frequencies in North Africa, the Middle East and Europe do not follow similar patterns, and their sub-clade divisions do not appear to be compatible with their shared history reaching back to the Early Upper Palaeolithic. The Bayesian Skyline Plots testify to non-overlapping phases of expansion, and the haplogroups’ phylogenies suggest that there are U6 sub-clades that expanded earlier than those in M1. Some M1 and U6 sub-clades could be linked with certain events. For example, U6a1 and M1b, with their coalescent ages of ~20,000–22,000 years ago and earliest inferred expansion in northwest Africa, could coincide with the flourishing of the Iberomaurusian industry, whilst U6b and M1b1 appeared at the time of the Capsian culture. Conclusions Our high-resolution phylogenetic dissection of both haplogroups and coalescent time assessments suggest that the extant main branching pattern of both haplogroups arose and diversified in the mid-later Upper Palaeolithic, with some sub-clades concomitantly with the expansion of the Iberomaurusian industry. Carriers of these maternal lineages have been later absorbed into and diversified further during the spread of Afro-Asiatic languages in North and East Africa. PMID:23206491

  2. Classification of metatarsophalangeal joint plantar plate injuries: history and physical examination variables.

    PubMed

    Nery, Caio; Coughlin, Michael J; Baumfeld, Daniel; Raduan, Fernando C; Mann, Tania Szejnfeld; Catena, Fernanda

    2014-01-01

    Although metatarsophalangeal (MTP) plantar plate tears are common, they are still often missed. The purpose of this study is to find the best clinical variables to define and grade the plantar plate injuries. Sixty-eight patients (100 MTP joints) were graded arthroscopically and divided into five groups (0 to IV) according to the anatomical classification. Their medical records were reviewed to establish correlations of clinical findings with the anatomical lesions. The positive correlations found were acute pain, widening of the interdigital space, loss of ground touch, positivity of the MTP joint drawer test, reduction of the toe purchase, and toe supination. The drawer test is the most reliable and accurate tool to classify and grade the plantar plate lesion, followed by ground touch and rotational deformities. It is possible to improve the accuracy of diagnosis of plantar plate tears by means of the combination of both clinical history and physical examination data.

  3. Early traces of the Second Demographic Transition in Bulgaria: a joint analysis of marital and non-marital union formation, 1960-2004.

    PubMed

    Hoem, Jan M; Kostova, Dora

    2008-11-01

    We explore trends in first-union formation in Bulgaria from 1960, using data from the national Gender and Generations Survey of 2004. We analyse jointly the transition into cohabitation and directly into marriage. The standardized marriage rate falls dramatically from the early 1980s; the corresponding rate of entry into cohabitation has already increased from the early 1960s but (surprisingly) falls moderately toward the end of our period. Cohabitation also tends to last progressively longer in more recent periods. The analysis shows that a pregnancy leads to a dramatic increase in the rate of both kinds of union formation: the increase is by a factor of almost 20 for marriage formation and about 10 for entry into cohabitation, ceteris paribus. Our findings suggest that, in Bulgaria at least, some manifestations of the Second Demographic Transition can be detected as early as the 1980s. PMID:18937141

  4. Sealable joint steel sheet piling for groundwater control and remediation: Case histories

    SciTech Connect

    Smyth, D.; Jowett, R.; Gamble, M.

    1997-12-31

    The Waterloo Barrier{trademark} steel sheet piling (patents pending) incorporates a cavity at each interlocking joint that is flushed clean and injected with sealant after the piles have been driven into the ground to form a vertical cutoff wall. The installation and sealing procedures allow for a high degree of quality assurance and control. Bulk wall hydraulic conductivities of 10{sup -8} to 10{sup -10} cm/sec have been demonstrated at field installations. Recent case histories are presented in which Waterloo Barrier{trademark} cutoff walls are used to prevent off-site migration of contaminated groundwater or soil gases to adjacent property and waterways. Full enclosures to isolate DNAPL source zones or portions of contaminated aquifers for pilot-scale remediation testing will also be described. Monitoring data will be used to demonstrate the effectiveness of the Waterloo Barrier{trademark} in these applications.

  5. The effect of talo-crural joint manipulation on range of motion at the ankle joint in subjects with a history of ankle injury.

    PubMed

    Andersen, Skye; Fryer, Gary A; McLaughlin, Patrick

    2003-07-01

    Introduction: There is little research available on the effects of peripheral joint manipulation. Only a few studies have examined the effect of manipulation on ankle range of motion, with conflicting results. This study aimed to determine whether a single high-velocity, low-amplitude (HVLA) thrust manipulation to the talo-crural joint altered ankle range of motion in subjects with a history of lateral ligament sprain.Methods: Male and female volunteers (N=52) with a history of lateral ligament sprain were randomly assigned into either an experimental group (n=26) or a control group (n=26). Those in the experimental group received a single HVLA thrust to the talo-crural joint, whilst those in the control group received no treatment intervention. Pre-test and post-test measurements of passive dorsiflexion range of motion were taken.Results: No significant changes in dorsiflexion range of motion were detected between manipulated ankles and those of control subjects using dependent and independent t-tests. Ankles that cavitated displayed a greater mean DFR and large effect size (d=0.8) compared to those that did not gap and cavitate, but analysis with ANOVA revealed these differences to be not significant.Conclusion: HVLA manipulation of the ankle did not increase dorsiflexion range of motion in subjects with a history of lateral ligament sprain.

  6. Effects of geological changes and climatic fluctuations on the demographic histories and low genetic diversity of Squaliobarbus curriculus in Yellow River.

    PubMed

    Zhou, Wei; Song, Na; Wang, Jun; Gao, Tianxiang

    2016-09-15

    The 104 samples of Squaliobarbus curriculus were collected from four localities in Yellow River and one region in Yangtze River. Analyses of the first hypervariable region of mitochondrial DNA control region of 555bp revealed only 15 polymorphism sites and defined 19 haplotypes. Low-to-moderate levels of haplotype diversity and low nucleotide diversity were observed in Yellow River populations (h=0.2529-0.7510, π=0.0712%-0.2197%). In contrast, Poyang Lake population showed high haplotype diversity and lower-middle nucleotide diversity (h=0.9636, π=0.5317%). Low genetic differentiation was estimated among Yellow River populations and significant level of genetic structure was detected between two rivers. Population genetic structure between two rivers was believed to be connected with geographical barriers and paleoclimatic events. The demographic history of S. curriculus in Yellow River examined by neutrality tests, mismatch distribution analysis, and Bayesian skyline analysis suggested a sudden and spatial population expansion dating to the Holocene. Climatic warming and changes of Yellow River course may have important effects on demographic facet of S. curriculus history. The same signal was also obtained on Poyang Lake population in late Pleistocene during the last interglacial period. During the period, the pronounced climatic change and the water system variation of PYL may have an important influence on the population. PMID:27317893

  7. Deeper insight into maternal genetic assessments and demographic history for Egyptian indigenous chicken populations using mtDNA analysis.

    PubMed

    Eltanany, Marwa A; Hemeda, Shabaan A

    2016-09-01

    This study principally sought to reveal the demographic expansion of Egyptian indigenous chickens (EIC) using representative breeds: Sinai (North), Fayoumi (Middle) and Dandarawi (South) of Egypt as well as to deeply clarify their genetic diversity, possible matrilineal origin and dispersal routes. A total of 33 partial mitochondrial DNA sequences were generated from EIC and compared with a worldwide reference dataset of 1290 wild and domestic chicken sequences. Study populations had 12 polymorphic variable sites and 7 haplotypes. A lack of maternal substructure between EIC was detected (F ST  = 0.003). The unimodal mismatch distribution and negative values of Tajima's D (-0.659) and Fu's Fs (-0.157) indicated demographic expansion among EIC and pointed to Fayoumi as the oldest EIC population. Egyptian haplotypes were clustered phylogenetically into two divergent clades. Their phylogeography revealed an ancient single maternal lineage of Egyptian chickens likely derived from Indian-Subcontinent. Moreover, a recent maternal commercial heritage possibly originated in Yunnan-Province and/or surrounding areas was admixed restrictedly into Sinai. It is implied that Egypt was an entry point for Indian chicken into Africa and its further dispersal route to Europe. This study provides a clue supporting the previous assumption that urged utilizing consistent founder populations having closely related progenitors for synthetizing a stabilized homogenous crossbreed as a sustainable discipline in breeding program. PMID:27489728

  8. Strong population genetic structure and contrasting demographic histories for the small-spotted catshark (Scyliorhinus canicula) in the Mediterranean Sea

    PubMed Central

    Kousteni, V; Kasapidis, P; Kotoulas, G; Megalofonou, P

    2015-01-01

    Coastal and demersal chondrichthyans, such as the small-spotted catshark, are expected to exhibit genetic differentiation in areas of complex geomorphology like the Mediterranean Basin because of their limited dispersal ability. To test this hypothesis, we used a fragment of the mitochondrial cytochrome c oxidase subunit I gene and 12 nuclear microsatellite loci in order to investigate the genetic structure and historical demography of this species, and to identify potential barriers to gene flow. Samples were collected from the Balearic Islands, the Algerian Basin, the Ionian Sea, the Corinthian Gulf and various locations across the Aegean Sea. Additional sequences from the Atlantic and the Levantine Basin retrieved from GenBank were included in the mitochondrial DNA analysis. Both mitochondrial and nuclear microsatellite DNA data revealed a strong genetic subdivision, mainly between the western and eastern Mediterranean, whereas the Levantine Basin shared haplotypes with both areas. The geographic isolation of the Mediterranean basins seems to enforce the population genetic differentiation of the species, with the deep sea acting as a strong barrier to its dispersal. Contrasting historical demographic patterns were also observed in different parts of the species' distribution, most notably a population growth trend in the western Mediterranean/Atlantic area and a slight decreasing one in the Aegean Sea. The different effects of the Pleistocene glacial periods on the habitat availability may explain the contrasting demographic patterns observed. The current findings suggest that the small-spotted catshark exhibits several genetic stocks in the Mediterranean, although further study is needed. PMID:25469687

  9. Strong population genetic structure and contrasting demographic histories for the small-spotted catshark (Scyliorhinus canicula) in the Mediterranean Sea.

    PubMed

    Kousteni, V; Kasapidis, P; Kotoulas, G; Megalofonou, P

    2015-03-01

    Coastal and demersal chondrichthyans, such as the small-spotted catshark, are expected to exhibit genetic differentiation in areas of complex geomorphology like the Mediterranean Basin because of their limited dispersal ability. To test this hypothesis, we used a fragment of the mitochondrial cytochrome c oxidase subunit I gene and 12 nuclear microsatellite loci in order to investigate the genetic structure and historical demography of this species, and to identify potential barriers to gene flow. Samples were collected from the Balearic Islands, the Algerian Basin, the Ionian Sea, the Corinthian Gulf and various locations across the Aegean Sea. Additional sequences from the Atlantic and the Levantine Basin retrieved from GenBank were included in the mitochondrial DNA analysis. Both mitochondrial and nuclear microsatellite DNA data revealed a strong genetic subdivision, mainly between the western and eastern Mediterranean, whereas the Levantine Basin shared haplotypes with both areas. The geographic isolation of the Mediterranean basins seems to enforce the population genetic differentiation of the species, with the deep sea acting as a strong barrier to its dispersal. Contrasting historical demographic patterns were also observed in different parts of the species' distribution, most notably a population growth trend in the western Mediterranean/Atlantic area and a slight decreasing one in the Aegean Sea. The different effects of the Pleistocene glacial periods on the habitat availability may explain the contrasting demographic patterns observed. The current findings suggest that the small-spotted catshark exhibits several genetic stocks in the Mediterranean, although further study is needed. PMID:25469687

  10. Socio-Demographic, Clinical and Behavioral Characteristics Associated with a History of Suicide Attempts among Psychiatric Outpatients: A Case Control Study in a Northern Mexican City

    PubMed Central

    Alvarado-Esquivel, Cosme; Sánchez-Anguiano, Luis Francisco; Arnaud-Gil, Carlos Alberto; Hernández-Tinoco, Jesús; Molina-Espinoza, Luis Fernando; Rábago-Sánchez, Elizabeth

    2014-01-01

    Background: Little is known about the epidemiology of suicide attempts among psychiatric outpatients in Mexico. This study was aimed to determine the socio-demographic, clinical and behavioral characteristics associated with suicide attempts in psychiatric outpatients in two public hospitals in Durango, Mexico. Methods: Two hundred seventy six psychiatric outpatients (154 suicide attempters and 122 patients without suicide attempt history) attended the two public hospitals in Durango City, Mexico were included in this study. Socio-demographic, clinical and behavioral characteristics were obtained retrospectively from all outpatients and compared in relation to the presence or absence of suicide attempt history. Results: Increased prevalence of suicide attempts was associated with mental and behavioral disorders due to psychoactive substance use (F10-19) (P=0.01), schizophrenia, schizotypal and delusional disorders (F20-29) (P=0.02), mood (affective) disorders (F30-39) (P<0.001), and disorders of adult personality and behavior (F60-69) (P<0.001). Multivariate analysis showed that suicide attempts were associated with young age (OR=1.21, 95% CI: 1.06-1.39; P=0.003), female gender (OR=2.98, 95% CI: 1.55-5.73; P=0.001), urban residence (OR=2.31, 95% CI: 1.17-4.57; P=0.01), memory impairment (OR=1.91, 95% CI: 1.07-3.40; P=0.02), alcohol consumption (OR=2.39, 95% CI: 1.21-4.70; P=0.01), and sexual promiscuity (OR=3.90, 95% CI: 1.74-8.77; P<0.001). Conclusions: We report the association of suicide attempts with socio-demographic, clinical and behavioral characteristics in psychiatric outpatients in Mexico. Results may be useful for an optimal planning of preventive measures against suicide attempts in psychiatric outpatients. PMID:24711751

  11. The joint effects of water and sanitation on diarrheal disease: A multi-country analysis of the Demographic and Health Surveys

    PubMed Central

    Fuller, James A.; Westphal, Joslyn A.; Kenney, Brooke; Eisenberg, Joseph N. S.

    2014-01-01

    Objectives To assess the joint effects of water and sanitation infrastructure, whether they are redundant services preventing the same cases of diarrheal disease, act independently, or act synergistically; and to assess how these effects vary by country and over time. Methods We used data from 217 Demographic and Health Surveys conducted in 90 countries between 1986 and 2013. We used modified Poisson regression to assess the impact of water and sanitation infra-structure on the prevalence of diarrhea among children under five. Results The impact of water and sanitation varied across surveys, and adjusting for socioeconomic status drove these estimates towards the null. Sanitation had a greater effect than water infrastructure when all 217 surveys were pooled; however, the impact of sanitation diminished over time. Based on survey data from the past ten years, we saw no evidence for benefits in improving drinking water or sanitation alone, but we estimated a 6% reduction of both combined (prevalence ratio = 0.94, 95% confidence limit 0.91-0.98). Conclusions Water and sanitation interventions should be combined to maximize the number of cases of diarrheal disease prevented in children under five. Further research should identify the sources of variability seen between countries and across time. These national surveys likely include substantial measurement error in the categorization of water and sanitation, making it difficult to interpret the roles of other pathways. PMID:25430739

  12. Did glacial advances during the Pleistocene influence differently the demographic histories of benthic and pelagic Antarctic shelf fishes? – Inferences from intraspecific mitochondrial and nuclear DNA sequence diversity

    PubMed Central

    Janko, Karel; Lecointre, Guillaume; DeVries, Arthur; Couloux, Arnaud; Cruaud, Corinne; Marshall, Craig

    2007-01-01

    species. However, the asynchronous timing of major demographic events observed in different species within both "ecological guilds", imply that the species examined here may have different population and evolutionary histories, and that more species should be analysed in order to more precisely assess the role of life history in the response of organisms to climatic changes. PMID:17997847

  13. Demographic histories of adaptively diverged riparian and non-riparian species of Ainsliaea (Asteraceae) inferred from coalescent analyses using multiple nuclear loci

    PubMed Central

    2012-01-01

    Background Understanding demographic histories, such as divergence time, patterns of gene flow, and population size changes, in ecologically diverging lineages provide implications for the process and maintenance of population differentiation by ecological adaptation. This study addressed the demographic histories in two independently derived lineages of flood-resistant riparian plants and their non-riparian relatives [Ainsliaea linearis (riparian) and A. apiculata (non-riparian); A. oblonga (riparian) and A. macroclinidioides (non-riparian); Asteraceae] using an isolation-with-migration (IM) model based on variation at 10 nuclear DNA loci. Results The highest posterior probabilities of the divergence time parameters were estimated to be ca. 25,000 years ago for A. linearis and A. apiculata and ca. 9000 years ago for A. oblonga and A. macroclinidioides, although the confidence intervals of the parameters had broad ranges. The likelihood ratio tests detected evidence of historical gene flow between both riparian/non-riparian species pairs. The riparian populations showed lower levels of genetic diversity and a significant reduction in effective population sizes compared to the non-riparian populations and their ancestral populations. Conclusions This study showed the recent origins of flood-resistant riparian plants, which are remarkable examples of plant ecological adaptation. The recent divergence and genetic signatures of historical gene flow among riparian/non-riparian species implied that they underwent morphological and ecological differentiation within short evolutionary timescales and have maintained their species boundaries in the face of gene flow. Comparative analyses of adaptive divergence in two sets of riparian/non-riparian lineages suggested that strong natural selection by flooding had frequently reduced the genetic diversity and size of riparian populations through genetic drift, possibly leading to fixation of adaptive traits in riparian

  14. Range-wide multilocus phylogeography of the red fox reveals ancient continental divergence, minimal genomic exchange and distinct demographic histories.

    PubMed

    Statham, Mark J; Murdoch, James; Janecka, Jan; Aubry, Keith B; Edwards, Ceiridwen J; Soulsbury, Carl D; Berry, Oliver; Wang, Zhenghuan; Harrison, David; Pearch, Malcolm; Tomsett, Louise; Chupasko, Judith; Sacks, Benjamin N

    2014-10-01

    Widely distributed taxa provide an opportunity to compare biogeographic responses to climatic fluctuations on multiple continents and to investigate speciation. We conducted the most geographically and genomically comprehensive study to date of the red fox (Vulpes vulpes), the world's most widely distributed wild terrestrial carnivore. Analyses of 697 bp of mitochondrial sequence in ~1000 individuals suggested an ancient Middle Eastern origin for all extant red foxes and a 400 kya (SD = 139 kya) origin of the primary North American (Nearctic) clade. Demographic analyses indicated a major expansion in Eurasia during the last glaciation (~50 kya), coinciding with a previously described secondary transfer of a single matriline (Holarctic) to North America. In contrast, North American matrilines (including the transferred portion of Holarctic clade) exhibited no signatures of expansion until the end of the Pleistocene (~12 kya). Analyses of 11 autosomal loci from a subset of foxes supported the colonization time frame suggested by mtDNA (and the fossil record) but, in contrast, reflected no detectable secondary transfer, resulting in the most fundamental genomic division of red foxes at the Bering Strait. Endemic continental Y-chromosome clades further supported this pattern. Thus, intercontinental genomic exchange was overall very limited, consistent with long-term reproductive isolation since the initial colonization of North America. Based on continental divergence times in other carnivoran species pairs, our findings support a model of peripatric speciation and are consistent with the previous classification of the North American red fox as a distinct species, V. fulva. PMID:25212210

  15. Comparing maternal genetic variation across two millennia reveals the demographic history of an ancient human population in southwest Turkey.

    PubMed

    Ottoni, Claudio; Rasteiro, Rita; Willet, Rinse; Claeys, Johan; Talloen, Peter; Van de Vijver, Katrien; Chikhi, Lounès; Poblome, Jeroen; Decorte, Ronny

    2016-02-01

    More than two decades of archaeological research at the site of Sagalassos, in southwest Turkey, resulted in the study of the former urban settlement in all its features. Originally settled in late Classical/early Hellenistic times, possibly from the later fifth century BCE onwards, the city of Sagalassos and its surrounding territory saw empires come and go. The Plague of Justinian in the sixth century CE, which is considered to have caused the death of up to a third of the population in Anatolia, and an earthquake in the seventh century CE, which is attested to have devastated many monuments in the city, may have severely affected the contemporary Sagalassos community. Human occupation continued, however, and Byzantine Sagalassos was eventually abandoned around 1200 CE. In order to investigate whether these historical events resulted in demographic changes across time, we compared the mitochondrial DNA variation of two population samples from Sagalassos (Roman and Middle Byzantine) and a modern sample from the nearby town of Ağlasun. Our analyses revealed no genetic discontinuity across two millennia in the region and Bayesian coalescence-based simulations indicated that a major population decline in the area coincided with the final abandonment of Sagalassos, rather than with the Plague of Justinian or the mentioned earthquake. PMID:26998313

  16. Population genomics shed light on the demographic and adaptive histories of European invasion in the Pacific oyster, Crassostrea gigas

    PubMed Central

    Rohfritsch, Audrey; Bierne, Nicolas; Boudry, Pierre; Heurtebise, Serge; Cornette, Florence; Lapègue, Sylvie

    2013-01-01

    Crassostrea gigas originated from the Pacific coast of Asia, but was introduced into several European countries in the early 1970s. Natural populations have now spread across the length of the western seaboard of Europe. To elucidate the demographic and selective processes at play during this rapid expansion, genome-scan analysis was performed on different populations. High diversities and low differentiation were observed overall, but significant genetic differentiation was found among newly established populations and between the newly established northern group and a nearly panmictic group composed of southern European populations and a population from Japan. Loss of genetic diversity was also seen in the north, likely caused by founder events during colonization. The few strongly supported outlier loci revealed a genetic structure uncorrelated with the north/south differentiation, but grouping two samples from the Danish fjords (northern group) and one from the Dutch Scheldt estuary (southern group) with the one from Japan. These findings might reflect the following: (i) parallel adaptation to similar environmental pressures (fjord-like environment) within each of the two groups or (ii) a footprint of a secondary introduction of an alternative genomic background maintained by multifarious isolation factors. Our results call for a closer examination of adaptive genetic structure in the area of origin. PMID:24187588

  17. Comparing maternal genetic variation across two millennia reveals the demographic history of an ancient human population in southwest Turkey

    PubMed Central

    Ottoni, Claudio; Willet, Rinse; Claeys, Johan; Talloen, Peter; Van de Vijver, Katrien; Chikhi, Lounès; Poblome, Jeroen; Decorte, Ronny

    2016-01-01

    More than two decades of archaeological research at the site of Sagalassos, in southwest Turkey, resulted in the study of the former urban settlement in all its features. Originally settled in late Classical/early Hellenistic times, possibly from the later fifth century BCE onwards, the city of Sagalassos and its surrounding territory saw empires come and go. The Plague of Justinian in the sixth century CE, which is considered to have caused the death of up to a third of the population in Anatolia, and an earthquake in the seventh century CE, which is attested to have devastated many monuments in the city, may have severely affected the contemporary Sagalassos community. Human occupation continued, however, and Byzantine Sagalassos was eventually abandoned around 1200 CE. In order to investigate whether these historical events resulted in demographic changes across time, we compared the mitochondrial DNA variation of two population samples from Sagalassos (Roman and Middle Byzantine) and a modern sample from the nearby town of Ağlasun. Our analyses revealed no genetic discontinuity across two millennia in the region and Bayesian coalescence-based simulations indicated that a major population decline in the area coincided with the final abandonment of Sagalassos, rather than with the Plague of Justinian or the mentioned earthquake. PMID:26998313

  18. Demographic history and asynchronous spawning shape genetic differentiation among populations of the hard coral Acropora tenuis in Western Australia.

    PubMed

    Rosser, Natalie L

    2016-05-01

    Genetic subdivision within populations can ultimately lead to the evolution of new species, and in populations of broadcast-spawners a potential facilitator of genetic subdivision is asynchronous reproduction. However, the factors that shape genetic variation in marine systems are complex and ambiguous, and ecological genetic structure may be influenced by the overriding signature of past demographic events. Here, the relative roles of the timing of reproduction and historical geography on the partitioning of genetic variation were examined in seven populations of the broadcast-spawning coral Acropora tenuis over 12° of latitude. The analysis of multiple loci (mitochondrial control region, two nuclear introns and six microsatellites) revealed significant genetic division between the most northern reef and all other reefs, suggesting that WA reefs were re-colonized from two different sources after the Pleistocene glaciation. Accompanying this pattern was significant genetic differentiation associated with different breeding seasons (spring and autumn), which was greatest in PaxC, in which there were two divergent lineages (ΦST=0.98). This is the second study to find divergent clades of PaxC associated with spring and autumn spawners, strengthening the suggestion of some selective connection to timing of reproduction in corals. This study reiterates the need to incorporate reproductive timing into population genetic studies of corals because it facilitates genetic differentiation; however, careful analysis of population genetic data is required to separate ecological and evolutionary processes. PMID:26876640

  19. Pragmatic Perspective on Conservation Genetics and Demographic History of the Last Surviving Population of Kashmir Red Deer (Cervus elaphus hanglu) in India

    PubMed Central

    Mukesh; Kumar, Ved P.; Sharma, Lalit K.; Shukla, Malay; Sathyakumar, Sambandam

    2015-01-01

    The hangul (Cervus elaphus hanglu) is of great conservation concern because it represents the easternmost and only hope for an Asiatic survivor of the red deer species in the Indian subcontinent. Despite the rigorous conservation efforts of the Department of Wildlife Protection in Jammu & Kashmir, the hangul population has experienced a severe decline in numbers and range contraction in the past few decades. The hangul population once abundant in the past has largely become confined to the Dachigam landscape, with a recent population estimate of 218 individuals. We investigated the genetic variability and demographic history of the hangul population and found that it has shown a relatively low diversity estimates when compared to other red deer populations of the world. Neutrality tests, which are used to evaluate demographic effects, did not support population expansion, and the multimodal pattern of mismatch distribution indicated that the hangul population is under demographic equilibrium. Furthermore, the hangul population did not exhibit any signature of bottleneck footprints in the past, and Coalescent Bayesian Skyline plot analysis revealed that the population had not experienced any dramatic changes in the effective population size over the last several thousand years. We observed a strong evidence of sub-structuring in the population, wherein the majority of individuals were assigned to different clusters in Bayesian cluster analysis. Population viability analysis demonstrated insignificant changes in the mean population size, with a positive growth rate projected for the next hundred years. We discuss the phylogenetic status of hangul for the first time among the other red deer subspecies of the world and strongly recommend to upgrade hangul conservation status under IUCN that should be discrete from the other red deer subspecies of the world to draw more conservation attention from national and international bodies. PMID:25671567

  20. Pragmatic perspective on conservation genetics and demographic history of the last surviving population of Kashmir red deer (Cervus elaphus hanglu) in India.

    PubMed

    Mukesh; Kumar, Ved P; Sharma, Lalit K; Shukla, Malay; Sathyakumar, Sambandam

    2015-01-01

    The hangul (Cervus elaphus hanglu) is of great conservation concern because it represents the easternmost and only hope for an Asiatic survivor of the red deer species in the Indian subcontinent. Despite the rigorous conservation efforts of the Department of Wildlife Protection in Jammu & Kashmir, the hangul population has experienced a severe decline in numbers and range contraction in the past few decades. The hangul population once abundant in the past has largely become confined to the Dachigam landscape, with a recent population estimate of 218 individuals. We investigated the genetic variability and demographic history of the hangul population and found that it has shown a relatively low diversity estimates when compared to other red deer populations of the world. Neutrality tests, which are used to evaluate demographic effects, did not support population expansion, and the multimodal pattern of mismatch distribution indicated that the hangul population is under demographic equilibrium. Furthermore, the hangul population did not exhibit any signature of bottleneck footprints in the past, and Coalescent Bayesian Skyline plot analysis revealed that the population had not experienced any dramatic changes in the effective population size over the last several thousand years. We observed a strong evidence of sub-structuring in the population, wherein the majority of individuals were assigned to different clusters in Bayesian cluster analysis. Population viability analysis demonstrated insignificant changes in the mean population size, with a positive growth rate projected for the next hundred years. We discuss the phylogenetic status of hangul for the first time among the other red deer subspecies of the world and strongly recommend to upgrade hangul conservation status under IUCN that should be discrete from the other red deer subspecies of the world to draw more conservation attention from national and international bodies.

  1. Selection and demographic history shape the molecular evolution of the gamete compatibility protein bindin in Pisaster sea stars

    PubMed Central

    Popovic, Iva; Marko, Peter B; Wares, John P; Hart, Michael W

    2014-01-01

    Reproductive compatibility proteins have been shown to evolve rapidly under positive selection leading to reproductive isolation, despite the potential homogenizing effects of gene flow. This process has been implicated in both primary divergence among conspecific populations and reinforcement during secondary contact; however, these two selective regimes can be difficult to discriminate from each other. Here, we describe the gene that encodes the gamete compatibility protein bindin for three sea star species in the genus Pisaster. First, we compare the full-length bindin-coding sequence among all three species and analyze the evolutionary relationships between the repetitive domains of the variable second bindin exon. The comparison suggests that concerted evolution of repetitive domains has an effect on bindin divergence among species and bindin variation within species. Second, we characterize population variation in the second bindin exon of two species: We show that positive selection acts on bindin variation in Pisaster ochraceus but not in Pisaster brevispinus, which is consistent with higher polyspermy risk in P. ochraceus. Third, we show that there is no significant genetic differentiation among populations and no apparent effect of sympatry with congeners that would suggest selection based on reinforcement. Fourth, we combine bindin and cytochrome c oxidase 1 data in isolation-with-migration models to estimate gene flow parameter values and explore the historical demographic context of our positive selection results. Our findings suggest that positive selection on bindin divergence among P. ochraceus alleles can be accounted for in part by relatively recent northward population expansions that may be coupled with the potential homogenizing effects of concerted evolution. PMID:24967076

  2. Selection and demographic history shape the molecular evolution of the gamete compatibility protein bindin in Pisaster sea stars.

    PubMed

    Popovic, Iva; Marko, Peter B; Wares, John P; Hart, Michael W

    2014-05-01

    Reproductive compatibility proteins have been shown to evolve rapidly under positive selection leading to reproductive isolation, despite the potential homogenizing effects of gene flow. This process has been implicated in both primary divergence among conspecific populations and reinforcement during secondary contact; however, these two selective regimes can be difficult to discriminate from each other. Here, we describe the gene that encodes the gamete compatibility protein bindin for three sea star species in the genus Pisaster. First, we compare the full-length bindin-coding sequence among all three species and analyze the evolutionary relationships between the repetitive domains of the variable second bindin exon. The comparison suggests that concerted evolution of repetitive domains has an effect on bindin divergence among species and bindin variation within species. Second, we characterize population variation in the second bindin exon of two species: We show that positive selection acts on bindin variation in Pisaster ochraceus but not in Pisaster brevispinus, which is consistent with higher polyspermy risk in P. ochraceus. Third, we show that there is no significant genetic differentiation among populations and no apparent effect of sympatry with congeners that would suggest selection based on reinforcement. Fourth, we combine bindin and cytochrome c oxidase 1 data in isolation-with-migration models to estimate gene flow parameter values and explore the historical demographic context of our positive selection results. Our findings suggest that positive selection on bindin divergence among P. ochraceus alleles can be accounted for in part by relatively recent northward population expansions that may be coupled with the potential homogenizing effects of concerted evolution. PMID:24967076

  3. Phylogeography across a continent: the evolutionary and demographic history of the North American racer (Serpentes: Colubridae: Coluber constrictor).

    PubMed

    Burbrink, Frank T; Fontanella, Frank; Alexander Pyron, R; Guiher, Timothy J; Jimenez, Cynthia

    2008-04-01

    Most phylogeographic studies examine organisms that do not have transcontinental distributions and therefore the genetic and temporal effects of barriers across an entire continent cannot be assessed with respect to a single species. We examined the phylogeographic structure, lineage age, and historical demography using sequences from the mtDNA cytochrome b gene of the widespread North American racer (Coluber constrictor), one of the few abundant transcontinental snakes that occurs throughout many diverse biomes. Our results indicate that this complex is comprised of six lineages differing greatly in geographic extent, with the largest (a central US clade) being approximately 26 times greater than the smallest (a lineage restricted to the Florida Panhandle and nearby portions of adjacent States). Most of the six lineages appear to be separated at previously identified genetic barriers for several vertebrates with similar ranges. Lineage diversification in this species began in the late Miocene, separating populations in the Florida Peninsula from the remainder of the US. Diversification of lineages continued throughout the Pliocene and early Pleistocene. Four of the six lineages occur east of the Mississippi River, with only two distinctly young ( approximately 1.5 mya) lineages found west of the Mississippi River (one occurs west of Continental Divide). All methods of demographic inference, including the mismatch distribution, Fu and Li's D and Tajima's D , and Bayesian skyline plots revealed population expansion occurring in the mid-to-late Pleistocene for every lineage, regardless of size or proximity to formerly glaciated areas. Population expansion for lineages found east of the Mississippi River occurred earlier and was much greater than those found west of the River. PMID:18093846

  4. Selection and demographic history shape the molecular evolution of the gamete compatibility protein bindin in Pisaster sea stars.

    PubMed

    Popovic, Iva; Marko, Peter B; Wares, John P; Hart, Michael W

    2014-05-01

    Reproductive compatibility proteins have been shown to evolve rapidly under positive selection leading to reproductive isolation, despite the potential homogenizing effects of gene flow. This process has been implicated in both primary divergence among conspecific populations and reinforcement during secondary contact; however, these two selective regimes can be difficult to discriminate from each other. Here, we describe the gene that encodes the gamete compatibility protein bindin for three sea star species in the genus Pisaster. First, we compare the full-length bindin-coding sequence among all three species and analyze the evolutionary relationships between the repetitive domains of the variable second bindin exon. The comparison suggests that concerted evolution of repetitive domains has an effect on bindin divergence among species and bindin variation within species. Second, we characterize population variation in the second bindin exon of two species: We show that positive selection acts on bindin variation in Pisaster ochraceus but not in Pisaster brevispinus, which is consistent with higher polyspermy risk in P. ochraceus. Third, we show that there is no significant genetic differentiation among populations and no apparent effect of sympatry with congeners that would suggest selection based on reinforcement. Fourth, we combine bindin and cytochrome c oxidase 1 data in isolation-with-migration models to estimate gene flow parameter values and explore the historical demographic context of our positive selection results. Our findings suggest that positive selection on bindin divergence among P. ochraceus alleles can be accounted for in part by relatively recent northward population expansions that may be coupled with the potential homogenizing effects of concerted evolution.

  5. Historical DNA reveals the demographic history of Atlantic cod (Gadus morhua) in medieval and early modern Iceland.

    PubMed

    Ólafsdóttir, Guðbjörg Ásta; Westfall, Kristen M; Edvardsson, Ragnar; Pálsson, Snæbjörn

    2014-02-22

    Atlantic cod (Gadus morhua) vertebrae from archaeological sites were used to study the history of the Icelandic Atlantic cod population in the time period of 1500-1990. Specifically, we used coalescence modelling to estimate population size and fluctuations from the sequence diversity at the cytochrome b (cytb) and Pantophysin I (PanI) loci. The models are consistent with an expanding population during the warm medieval period, large historical effective population size (NE), a marked bottleneck event at 1400-1500 and a decrease in NE in early modern times. The model results are corroborated by the reduction of haplotype and nucleotide variation over time and pairwise population distance as a significant portion of nucleotide variation partitioned across the 1550 time mark. The mean age of the historical fished stock is high in medieval times with a truncation in age in early modern times. The population size crash coincides with a period of known cooling in the North Atlantic, and we conclude that the collapse may be related to climate or climate-induced ecosystem change.

  6. Historical DNA reveals the demographic history of Atlantic cod (Gadus morhua) in medieval and early modern Iceland

    PubMed Central

    Ólafsdóttir, Guðbjörg Ásta; Westfall, Kristen M.; Edvardsson, Ragnar; Pálsson, Snæbjörn

    2014-01-01

    Atlantic cod (Gadus morhua) vertebrae from archaeological sites were used to study the history of the Icelandic Atlantic cod population in the time period of 1500–1990. Specifically, we used coalescence modelling to estimate population size and fluctuations from the sequence diversity at the cytochrome b (cytb) and Pantophysin I (PanI) loci. The models are consistent with an expanding population during the warm medieval period, large historical effective population size (NE), a marked bottleneck event at 1400–1500 and a decrease in NE in early modern times. The model results are corroborated by the reduction of haplotype and nucleotide variation over time and pairwise population distance as a significant portion of nucleotide variation partitioned across the 1550 time mark. The mean age of the historical fished stock is high in medieval times with a truncation in age in early modern times. The population size crash coincides with a period of known cooling in the North Atlantic, and we conclude that the collapse may be related to climate or climate-induced ecosystem change. PMID:24403343

  7. Population Structure, Genetic Diversity, Effective Population Size, Demographic History and Regional Connectivity Patterns of the Endangered Dusky Grouper, Epinephelus marginatus (Teleostei: Serranidae), within Malta's Fisheries Management Zone.

    PubMed

    Buchholz-Sørensen, Molly; Vella, Adriana

    2016-01-01

    The objective of this study is to describe the genetic population structure and demographic history of the endangered marine fish, Epinephelus marginatus, within Malta's Fisheries Management Zone for the purpose of localised conservation planning. Epinephelus marginatus is a long-lived, sedentary, reef-associated protogynous hermaphrodite with high commercial and recreational value that is at risk of extinction throughout its global distribution. Based on global trends, population substructuring and gaps in local knowledge this has led to an increased interest in evaluation of local stock. Assessment of Maltese demography was based on historical and contemporary catch landings data whilst genetic population structure and regional connectivity patterns were evaluated by examining 175 individuals collected within the central Mediterranean region between 2002 and 2009 using 14 nuclear microsatellite loci. Demographic stock assessment of Maltese E. marginatus' revealed a 99% decline in catch landings between 1947 and 2009 within the Fisheries Management Zone. A contemporary modest mean size was observed, 3 ± 3 kg, where approximately 17% of the population was juvenile, 68% female/sex-changing and 15% were male with a male-to-female sex ratio of 1:5. Genetic analysis describes the overall population of E. marginatus' within the Fisheries Management Zone as decreasing in size (ƟH = 2.2), which has gone through a significant size reduction in the past (M = 0.41) and consequently shows signs of moderate inbreeding (FIS = 0.10, p < 0.001) with an estimated effective population size of 130 individuals. Results of spatially explicit Bayesian genetic cluster analysis detected two geographically distinct subpopulations within Malta's Fisheries Management Zone and that they are connected to a larger network of E. marginatus' within the Sicily Channel. Results suggest conservation management should be designed to reflect E. marginatus' within Malta's Fisheries Management Zone

  8. Population Structure, Genetic Diversity, Effective Population Size, Demographic History and Regional Connectivity Patterns of the Endangered Dusky Grouper, Epinephelus marginatus (Teleostei: Serranidae), within Malta's Fisheries Management Zone.

    PubMed

    Buchholz-Sørensen, Molly; Vella, Adriana

    2016-01-01

    The objective of this study is to describe the genetic population structure and demographic history of the endangered marine fish, Epinephelus marginatus, within Malta's Fisheries Management Zone for the purpose of localised conservation planning. Epinephelus marginatus is a long-lived, sedentary, reef-associated protogynous hermaphrodite with high commercial and recreational value that is at risk of extinction throughout its global distribution. Based on global trends, population substructuring and gaps in local knowledge this has led to an increased interest in evaluation of local stock. Assessment of Maltese demography was based on historical and contemporary catch landings data whilst genetic population structure and regional connectivity patterns were evaluated by examining 175 individuals collected within the central Mediterranean region between 2002 and 2009 using 14 nuclear microsatellite loci. Demographic stock assessment of Maltese E. marginatus' revealed a 99% decline in catch landings between 1947 and 2009 within the Fisheries Management Zone. A contemporary modest mean size was observed, 3 ± 3 kg, where approximately 17% of the population was juvenile, 68% female/sex-changing and 15% were male with a male-to-female sex ratio of 1:5. Genetic analysis describes the overall population of E. marginatus' within the Fisheries Management Zone as decreasing in size (ƟH = 2.2), which has gone through a significant size reduction in the past (M = 0.41) and consequently shows signs of moderate inbreeding (FIS = 0.10, p < 0.001) with an estimated effective population size of 130 individuals. Results of spatially explicit Bayesian genetic cluster analysis detected two geographically distinct subpopulations within Malta's Fisheries Management Zone and that they are connected to a larger network of E. marginatus' within the Sicily Channel. Results suggest conservation management should be designed to reflect E. marginatus' within Malta's Fisheries Management Zone

  9. Evaluation and management of joint pain.

    PubMed

    Collyott, Cindy L; Brooks, Mirella Vasquez

    2008-01-01

    The purpose of this article was to provide a review for orthopaedic nurses and nurse practitioners who evaluate, manage, and care for patients with joint pain. Joint pain is a common complaint evaluated by primary care providers. The causation of joint pain is complicated to identify because of an extensive range of differential diagnosis. The history and physical examination are crucial components in evaluating and managing joint pain. The primary care provider uses clinical factors such as patient demographics, presence of inflammation, acute/chronic duration, extra-articular manifestations, pattern of joint involvement, and disease chronology. Many rheumatologic laboratory tests are nonspecific, but aspiration of the joint with synovial fluid analysis may provide diagnostic clues, especially to differentiate infection versus inflammation. Primary care providers utilize both pharmacologic and nonpharmacologic regimens to manage acute and chronic joint pain.

  10. Demographic study of port wine stain patients attending a laser clinic: family history, prevalence of naevus anaemicus and results of prior treatment.

    PubMed

    Mills, C M; Lanigan, S W; Hughes, J; Anstey, A V

    1997-07-01

    All patients with port wine stains (PWS) attending a tunable dye laser clinic were examined by one author (SWL), forming a large group which has allowed study of the demographic data of such patients. Two hundred and eighty-three patients, 217 females (median age 24 years, range 0.5-73) and 66 males (median age 20 years, range 0.75-72), were examined. The PWS were on the face in 226, neck in 69, trunk in 36, upper limb in 35 and lower limb in 29. The commonest lesional colour was purple (63 patients), while 39 naevi were pink/red, 35 pink/ purple and 35 pink. The naevus was flat in 255 patients, cobblestoned in 28, associated with hypertrophy in 31 and with scarring in 22. Seventy-two patients (25.4%) had a positive family history of birthmarks, 20 strawberry haemangiomas and 22 PWS, the family history of PWS being higher than expected for the prevalence of this naevus in the population. One hundred and forty-six patients were also examined for naevus anaemicus which was noted in 12 (8.2%), confirming an association between these two naevi. Ninety-four patients had received previous treatment, most commonly with the argon laser (56 patients), of whom only five reported a good result, and 17 of 22 patients with treatment-related scarring had been treated with this laser. Cosmetic camouflage was used in 109 (38.5%) of patients, who usually had PWS on the face (94%), of whom only 46 (16%) had received advice of its use. PMID:9499604

  11. The Effect of Velocity of Joint Mobilization on Corticospinal Excitability in Individuals With a History of Ankle Sprain.

    PubMed

    Fisher, Beth E; Piraino, Andrew; Lee, Ya-Yun; Smith, Jo Armour; Johnson, Sean; Davenport, Todd E; Kulig, Kornelia

    2016-07-01

    Study Design Controlled laboratory study. Background Joint mobilization and manipulation decrease pain and improve patient function. Yet, the processes underlying these changes are not well understood. Measures of corticospinal excitability provide insight into potential mechanisms mediated by the central nervous system. Objectives To investigate the differential effects of joint mobilization and manipulation at the talocrural joint on corticospinal excitability in individuals with resolved symptoms following ankle sprain. Methods Twenty-seven participants with a history of ankle sprain were randomly assigned to the control, joint mobilization, or thrust manipulation group. The motor-evoked potential (MEP) and cortical silent period (CSP) of the tibialis anterior and gastrocnemius were obtained with transcranial magnetic stimulation at rest and during active contraction of the tibialis anterior. The slopes of MEP/CSP input/output curves and the maximal MEP/CSP values were calculated to indicate corticospinal excitability. Behavioral measures, including ankle dorsiflexion and dynamic balance, were evaluated. Results A repeated-measures analysis of variance of the MEP slope showed a significant group-by-time interaction for the tibialis anterior at rest (P = .002) and during active contraction (P = .042). After intervention, the thrust manipulation group had an increase in corticospinal excitability, while the corticospinal excitability decreased in the mobilization group. The thrust manipulation group, but not other groups, also demonstrated a significant increase in the maximal MEP amplitude of the tibialis anterior after intervention. Conclusion The findings suggest that joint manipulation and mobilization have different effects on corticospinal excitability. The increased corticospinal excitability following thrust manipulation may provide a window for physical therapists to optimize muscle recruitment and subsequently movement. The trial was registered at

  12. Patterns of variation at Ustilago maydis virulence clusters 2A and 19A largely reflect the demographic history of its populations.

    PubMed

    Kellner, Ronny; Hanschke, Christian; Begerow, Dominik

    2014-01-01

    The maintenance of an intimate interaction between plant-biotrophic fungi and their hosts over evolutionary times involves strong selection and adaptative evolution of virulence-related genes. The highly specialised maize pathogen Ustilago maydis is assigned with a high evolutionary capability to overcome host resistances due to its high rates of sexual recombination, large population sizes and long distance dispersal. Unlike most studied fungus-plant interactions, the U. maydis - Zea mays pathosystem lacks a typical gene-for-gene interaction. It exerts a large set of secreted fungal virulence factors that are mostly organised in gene clusters. Their contribution to virulence has been experimentally demonstrated but their genetic diversity within U. maydis remains poorly understood. Here, we report on the intraspecific diversity of 34 potential virulence factor genes of U. maydis. We analysed their sequence polymorphisms in 17 isolates of U. maydis from Europe, North and Latin America. We focused on gene cluster 2A, associated with virulence attenuation, cluster 19A that is crucial for virulence, and the cluster-independent effector gene pep1. Although higher compared to four house-keeping genes, the overall levels of intraspecific genetic variation of virulence clusters 2A and 19A, and pep1 are remarkably low and commensurate to the levels of 14 studied non-virulence genes. In addition, each gene is present in all studied isolates and synteny in cluster 2A is conserved. Furthermore, 7 out of 34 virulence genes contain either no polymorphisms or only synonymous substitutions among all isolates. However, genetic variation of clusters 2A and 19A each resolve the large scale population structure of U. maydis indicating subpopulations with decreased gene flow. Hence, the genetic diversity of these virulence-related genes largely reflect the demographic history of U. maydis populations. PMID:24887029

  13. Molecular demographic history of the annual sunflowers Helianthus annuus and H. petiolaris--large effective population sizes and rates of long-term gene flow.

    PubMed

    Strasburg, Jared L; Rieseberg, Loren H

    2008-08-01

    Hybridization between distinct species may lead to introgression of genes across species boundaries, and this pattern can potentially persist for extended periods as long as selection at some loci or genomic regions prevents thorough mixing of gene pools. However, very few reliable estimates of long-term levels of effective migration are available between hybridizing species throughout their history. Accurate estimates of divergence dates and levels of gene flow require data from multiple unlinked loci as well as an analytical framework that can distinguish between lineage sorting and gene flow and incorporate the effects of demographic changes within each species. Here we use sequence data from 18 anonymous nuclear loci in two broadly sympatric sunflower species, Helianthus annuus and H. petiolaris, analyzed within an "isolation with migration" framework to make genome-wide estimates of the ages of these two species, long-term rates of gene flow between them, and effective population sizes and historical patterns of population growth. Our results indicate that H. annuus and H. petiolaris are approximately one million years old and have exchanged genes at a surprisingly high rate (long-term N(ef)m estimates of approximately 0.5 in each direction), with somewhat higher rates of introgression from H. annuus into H. petiolaris than vice versa. In addition, each species has undergone dramatic population expansion since divergence, and both species have among the highest levels of genetic diversity reported for flowering plants. Our results provide the most comprehensive estimate to date of long-term patterns of gene flow and historical demography in a nonmodel plant system, and they indicate that species integrity can be maintained even in the face of extensive gene flow over a prolonged period.

  14. Genetic structure and demographic history reveal migration of the diamondback moth Plutella xylostella (Lepidoptera: Plutellidae) from the southern to northern regions of China.

    PubMed

    Wei, Shu-Jun; Shi, Bao-Cai; Gong, Ya-Jun; Jin, Gui-Hua; Chen, Xue-Xin; Meng, Xiang-Feng

    2013-01-01

    The diamondback moth Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) is one of the most destructive insect pests of cruciferous plants worldwide. Biological, ecological and genetic studies have indicated that this moth is migratory in many regions around the world. Although outbreaks of this pest occur annually in China and cause heavy damage, little is known concerning its migration. To better understand its migration pattern, we investigated the population genetic structure and demographic history of the diamondback moth by analyzing 27 geographical populations across China using four mitochondrial genes and nine microsatellite loci. The results showed that high haplotype diversity and low nucleotide diversity occurred in the diamondback moth populations, a finding that is typical for migratory species. No genetic differentiation among all populations and no correlation between genetic and geographical distance were found. However, pairwise analysis of the mitochondrial genes has indicated that populations from the southern region were more differentiated than those from the northern region. Gene flow analysis revealed that the effective number of migrants per generation into populations of the northern region is very high, whereas that into populations of the southern region is quite low. Neutrality testing, mismatch distribution and Bayesian Skyline Plot analyses based on mitochondrial genes all revealed that deviation from Hardy-Weinberg equilibrium and sudden expansion of the effective population size were present in populations from the northern region but not in those from the southern region. In conclusion, all our analyses strongly demonstrated that the diamondback moth migrates within China from the southern to northern regions with rare effective migration in the reverse direction. Our research provides a successful example of using population genetic approaches to resolve the seasonal migration of insects.

  15. Patterns of variation at Ustilago maydis virulence clusters 2A and 19A largely reflect the demographic history of its populations.

    PubMed

    Kellner, Ronny; Hanschke, Christian; Begerow, Dominik

    2014-01-01

    The maintenance of an intimate interaction between plant-biotrophic fungi and their hosts over evolutionary times involves strong selection and adaptative evolution of virulence-related genes. The highly specialised maize pathogen Ustilago maydis is assigned with a high evolutionary capability to overcome host resistances due to its high rates of sexual recombination, large population sizes and long distance dispersal. Unlike most studied fungus-plant interactions, the U. maydis - Zea mays pathosystem lacks a typical gene-for-gene interaction. It exerts a large set of secreted fungal virulence factors that are mostly organised in gene clusters. Their contribution to virulence has been experimentally demonstrated but their genetic diversity within U. maydis remains poorly understood. Here, we report on the intraspecific diversity of 34 potential virulence factor genes of U. maydis. We analysed their sequence polymorphisms in 17 isolates of U. maydis from Europe, North and Latin America. We focused on gene cluster 2A, associated with virulence attenuation, cluster 19A that is crucial for virulence, and the cluster-independent effector gene pep1. Although higher compared to four house-keeping genes, the overall levels of intraspecific genetic variation of virulence clusters 2A and 19A, and pep1 are remarkably low and commensurate to the levels of 14 studied non-virulence genes. In addition, each gene is present in all studied isolates and synteny in cluster 2A is conserved. Furthermore, 7 out of 34 virulence genes contain either no polymorphisms or only synonymous substitutions among all isolates. However, genetic variation of clusters 2A and 19A each resolve the large scale population structure of U. maydis indicating subpopulations with decreased gene flow. Hence, the genetic diversity of these virulence-related genes largely reflect the demographic history of U. maydis populations.

  16. Genetic structure and demographic history reveal migration of the diamondback moth Plutella xylostella (Lepidoptera: Plutellidae) from the southern to northern regions of China.

    PubMed

    Wei, Shu-Jun; Shi, Bao-Cai; Gong, Ya-Jun; Jin, Gui-Hua; Chen, Xue-Xin; Meng, Xiang-Feng

    2013-01-01

    The diamondback moth Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) is one of the most destructive insect pests of cruciferous plants worldwide. Biological, ecological and genetic studies have indicated that this moth is migratory in many regions around the world. Although outbreaks of this pest occur annually in China and cause heavy damage, little is known concerning its migration. To better understand its migration pattern, we investigated the population genetic structure and demographic history of the diamondback moth by analyzing 27 geographical populations across China using four mitochondrial genes and nine microsatellite loci. The results showed that high haplotype diversity and low nucleotide diversity occurred in the diamondback moth populations, a finding that is typical for migratory species. No genetic differentiation among all populations and no correlation between genetic and geographical distance were found. However, pairwise analysis of the mitochondrial genes has indicated that populations from the southern region were more differentiated than those from the northern region. Gene flow analysis revealed that the effective number of migrants per generation into populations of the northern region is very high, whereas that into populations of the southern region is quite low. Neutrality testing, mismatch distribution and Bayesian Skyline Plot analyses based on mitochondrial genes all revealed that deviation from Hardy-Weinberg equilibrium and sudden expansion of the effective population size were present in populations from the northern region but not in those from the southern region. In conclusion, all our analyses strongly demonstrated that the diamondback moth migrates within China from the southern to northern regions with rare effective migration in the reverse direction. Our research provides a successful example of using population genetic approaches to resolve the seasonal migration of insects. PMID:23565158

  17. Encounter history modeling of joint mark-recapture, tag-resighting and tag-recovery data under temporary emigration

    USGS Publications Warehouse

    Barker, R.J.; Burnham, K.P.; White, Gary C.

    2004-01-01

    We describe a joint analysis of mark-recapture, tag-resight and tag-recovery data that directly models the encounter history of an animal. The probability of the encounter history for each animal is partitioned into survival, recapture, resighting, and recovery components, and a component for the probability that the animal is never encountered again. Temporary migration enters into the likelihood through the recapture component, and movement of marked animals in and out of the area where they are subject to capture is modeled using a Markov chain. Random temporary emigration and permanent emigration are special cases. An important feature of directly modeling the encounter histories is that covariates that are specific to individuals can be included in the analysis. The model is applied to a brown trout tagging data set and provides strong evidence of Markovian temporary emigration. The new model is needed to provide correct estimates of trout survival probabilities which are shown to depend on the length of the fish at first capture.

  18. Hallmarks in the history of orthopaedic implants for trauma and joint replacement.

    PubMed

    Markatos, Konstantinos; Tsoucalas, Gregory; Sgantzos, Markos

    2016-08-01

    This manuscript represents an attempt to review orthopaedic implants and reconstructive orthopaedic surgery for lower limbs lesions or trauma mainly in the 20th century. We emphasized on the type of implants, the biomaterials and their evolution, and we also engaged in a special reference for the pioneers of orthopaedic implant surgery and the innovative designers of those implants, in such a way to understand the ways and the stages through which they evolved to their present forms, as well as the scientific principles that affected their design and progress. A correlation between the evolution of implants and several relevant disciplines (biomaterial chemists and engineers, biomechanics) that developed simultaneously with orthopaedic reconstructive joint surgery is present since the first attempts to reconstruct a damaged joint. In the future, further progress is anticipated in the use of biomaterials, more compatible towards human biology, with minimally invasive applications and a perpetually increased life span. This progress depicts a phenomenon directly related to a multilevel, multifactorial and interdisciplinary scientific and technological field with many expectations. PMID:27598960

  19. Demographic consequences of climate change and land cover help explain a history of extirpations and range contraction in a declining snake species.

    PubMed

    Pomara, Lars Y; LeDee, Olivia E; Martin, Karl J; Zuckerberg, Benjamin

    2014-07-01

    Developing conservation strategies for threatened species increasingly requires understanding vulnerabilities to climate change, in terms of both demographic sensitivities to climatic and other environmental factors, and exposure to variability in those factors over time and space. We conducted a range-wide, spatially explicit climate change vulnerability assessment for Eastern Massasauga (Sistrurus catenatus), a declining endemic species in a region showing strong environmental change. Using active season and winter adult survival estimates derived from 17 data sets throughout the species' range, we identified demographic sensitivities to winter drought, maximum precipitation during the summer, and the proportion of the surrounding landscape dominated by agricultural and urban land cover. Each of these factors was negatively associated with active season adult survival rates in binomial generalized linear models. We then used these relationships to back-cast adult survival with dynamic climate variables from 1950 to 2008 using spatially explicit demographic models. Demographic models for 189 population locations predicted known extant and extirpated populations well (AUC = 0.75), and models based on climate and land cover variables were superior to models incorporating either of those effects independently. These results suggest that increasing frequencies and severities of extreme events, including drought and flooding, have been important drivers of the long-term spatiotemporal variation in a demographic rate. We provide evidence that this variation reflects nonadaptive sensitivity to climatic stressors, which are contributing to long-term demographic decline and range contraction for a species of high-conservation concern. Range-wide demographic modeling facilitated an understanding of spatial shifts in climatic suitability and exposure, allowing the identification of important climate refugia for a dispersal-limited species. Climate change vulnerability

  20. Dounreay PFR irradiation history for the joint US/UK actinide sample exposures

    SciTech Connect

    Raman, S.; Murphy, B.D.; Nestor, C.W. Jr.

    1995-07-01

    The operating history of the Dounreay Prototype Fast Reactor is presented to the extent that it is relevant to the irradiation of actinide specimens that were subsequently analyzed at Oak Ridge National Laboratory (ORNL). Three fuel pins with actinide samples were irradiated from July 1982 to July 1988 and returned to ORNL for analysis. They contained isotopes of elements from thorium to curium. The times when each of these fuel pins were in the reactor core are described as are the operating power levels and neutron spectra. The appendices give daily power levels of the reactor as well as six-group neutron energy spectra for various times and axial positions in the core.

  1. A joint history of the nature of genetic variation and the nature of schizophrenia.

    PubMed

    Kendler, K S

    2015-02-01

    This essay traces the history of concepts of genetic variation and schizophrenia from Darwin and Mendel to the present. For Darwin, the important form of genetic variation for evolution is continuous in nature and small in effect. Biometricians led by Pearson agreed and developed statistical genetic approaches utilizing trait correlations in relatives. Mendel studied discontinuous traits and subsequent Mendelians, led by Bateson, assumed that important genetic variation was large in effect producing discontinuous phenotypes. Although biometricians studied 'insanity', schizophrenia genetics under Kraepelin and Rüdin utilized Mendelian approaches congruent with their anatomical-clinical disease model of dementia praecox. Fisher showed, assuming many genes of small effect, Mendelian and Biometrical models were consilient. Echoing prior conflicts, psychiatric genetics since then has utilized both biometrical models, largely in twins, and Mendelian models, based on advancing molecular techniques. In 1968, Gottesman proposed a polygenic model for schizophrenia based on a threshold version of Fisher's theory. Since then, rigorous studies of the schizophrenia spectrum suggest that genetic risk for schizophrenia is more likely continuous than categorical. The last 5 years has seen increasingly convincing evidence from genome-wide association study (GWAS) and sequencing that genetic risk for schizophrenia is largely polygenic, and congruent with Fisher's and Gottesman's models. The gap between biometrical and molecular Mendelian models for schizophrenia has largely closed. The efforts to ground a categorical biomedical model of schizophrenia in Mendelian genetics have failed. The genetic risk for schizophrenia is widely distributed in human populations so that we all carry some degree of risk.

  2. Look before You Leap: Underestimating Chinese Student History, Chinese University Setting and Chinese University Steering in Sino-British HE Joint Ventures?

    ERIC Educational Resources Information Center

    Dow, Ewan G.

    2010-01-01

    This article makes the case--in three parts--that many Anglo-Chinese university collaborations (joint ventures) to date have seriously underestimated Chinese (student) history, the Chinese university setting and Chinese national governmental steering as part of the process of "glocalisation". Recent turbulence in this particular HE collaborative…

  3. A joint history of the nature of genetic variation and the nature of schizophrenia.

    PubMed

    Kendler, K S

    2015-02-01

    This essay traces the history of concepts of genetic variation and schizophrenia from Darwin and Mendel to the present. For Darwin, the important form of genetic variation for evolution is continuous in nature and small in effect. Biometricians led by Pearson agreed and developed statistical genetic approaches utilizing trait correlations in relatives. Mendel studied discontinuous traits and subsequent Mendelians, led by Bateson, assumed that important genetic variation was large in effect producing discontinuous phenotypes. Although biometricians studied 'insanity', schizophrenia genetics under Kraepelin and Rüdin utilized Mendelian approaches congruent with their anatomical-clinical disease model of dementia praecox. Fisher showed, assuming many genes of small effect, Mendelian and Biometrical models were consilient. Echoing prior conflicts, psychiatric genetics since then has utilized both biometrical models, largely in twins, and Mendelian models, based on advancing molecular techniques. In 1968, Gottesman proposed a polygenic model for schizophrenia based on a threshold version of Fisher's theory. Since then, rigorous studies of the schizophrenia spectrum suggest that genetic risk for schizophrenia is more likely continuous than categorical. The last 5 years has seen increasingly convincing evidence from genome-wide association study (GWAS) and sequencing that genetic risk for schizophrenia is largely polygenic, and congruent with Fisher's and Gottesman's models. The gap between biometrical and molecular Mendelian models for schizophrenia has largely closed. The efforts to ground a categorical biomedical model of schizophrenia in Mendelian genetics have failed. The genetic risk for schizophrenia is widely distributed in human populations so that we all carry some degree of risk. PMID:25134695

  4. Generation and application of a standardized load-time history to tubular T-joints in offshore platforms

    NASA Astrophysics Data System (ADS)

    Li, Shan-shan; Cui, Wei-cheng

    2015-10-01

    Marine structures are mostly made of metals and always experience complex random loading during their service periods. The fatigue crack growth behaviors of metal materials have been proved from laboratory tests to be sensitive to the loading sequence encountered. In order to take account of the loading sequence effect, fatigue life prediction should be based on fatigue crack propagation (FCP) theory rather than the currently used cumulative fatigue damage (CFD) theory. A unified fatigue life prediction (UFLP) method for marine structures has been proposed by the authors' group. In order to apply the UFLP method for newly designed structures, authorities such as the classification societies should provide a standardized load-time history (SLH) such as the TWIST and FALSTAFF sequences for transport and fighter aircraft. This paper mainly aims at proposing a procedure to generate the SLHs for marine structures based on a short-term loading sample and to provide an illustration on how to use the presented SLH to a typical tubular T-joint in an offshore platform based on the UFLP method.

  5. Paleoeskimo Demographic History in the Canadian Arctic (ca. 4800-800 B.P.) and its Relationship to Mid-Late Holocene Climate Variability.

    NASA Astrophysics Data System (ADS)

    Savelle, J. M.

    2014-12-01

    Paleoeskimos were the first occupants of the central and eastern Canadian Arctic, spreading east from the Bering Strait region beginning approximately 4800 B.P., and occupied much of the Canadian Arctic through to their eventual disappearance ca. 800 B.P. Extensive regional archaeological site surveys throughout this area by the author and Arthur S. Dyke indicate that Paleoskimo populations underwent a series of population 'boom' (rapid expansion) and 'bust' (population declines and local extinctions) over the 4,000 year occupation history, including in the purported stable 'core area' of Foxe Basin. In this paper, we examine the contemporaneity of the local boom and bust cycles in a pan-Canadian Arctic context, and in turn examine the relationship of these cycles to mid-late Holocene climate variability.

  6. History of the Balkans: Twentieth Century. Volume 2. The Joint Committee on Eastern Europe Publication Series. No. 12.

    ERIC Educational Resources Information Center

    Jelavich, Barbara

    Principal issues in the 20th century development of the Balkan Peninsula are discussed in this introductory history text. Three themes--national rivalries, great power interference, and the economic, social, and political problems of modernization--are given special emphasis. An overview of 18th and 19th century history precedes the two major…

  7. Whole-genome sequencing reveals absence of recent gene flow and separate demographic histories for Anopheles punctulatus mosquitoes in Papua New Guinea

    PubMed Central

    LOGUE, KYLE; SMALL, SCOTT T.; CHAN, ERNEST R.; REIMER, LISA; SIBA, PETER M.; ZIMMERMAN, PETER A.; SERRE, DAVID

    2015-01-01

    Anopheles mosquitoes are the vectors of several human diseases including malaria. In many malaria endemic areas, several species of Anopheles coexist, sometimes in the form of related sibling species that are morphologically indistinguishable. Determining the size and organization of Anopheles populations, and possible ongoing gene flow among them is important for malaria control and, in particular, for monitoring the spread of insecticide resistance alleles. However, these parameters have been difficult to evaluate in most Anopheles species due to the paucity of genetic data available. Here, we assess the extent of contemporary gene flow and historical variations in population size by sequencing and de novo assembling the genomes of wild-caught mosquitoes from four species of the Anopheles punctulatus group of Papua New Guinea. Our analysis of more than 50 Mb of orthologous DNA sequences revealed no evidence of contemporary gene flow among these mosquitoes. In addition, investigation of the demography of two of the An. punctulatus species revealed distinct population histories. Overall, our analyses suggest that, despite their similarities in morphology, behaviour and ecology, contemporary sympatric populations of An. punctulatus are evolving independently. PMID:25677924

  8. Demographic and life-history patterns in a population of ring-tailed lemurs (Lemur catta) at Beza Mahafaly Reserve, Madagascar: a 15-year perspective.

    PubMed

    Gould, Lisa; Sussman, R W; Sauther, Michelle L

    2003-02-01

    Over 15 field seasons (1987-2001), we collected census and life-history data on a population of individually identified ring-tailed lemurs at the Beza Mahafaly Reserve, Madagascar. No significant difference was found in population size over the study period, though a marked decline in the population occurred following a 2-year drought. The population rebounded rapidly after the immediate postdrought period. There was nearly a complete replacement of individuals over the study period. Average group size is 11.5 animals, and adult male to female sex ratio is 0.92. Most females reproduce annually, and the average fecundity rate is 84.3%. The greatest variability in fecundity is found among old females. We suggest that ring-tailed lemur females follow an "income breeding" strategy, i.e., females use maximum resources during reproduction rather than relying on fat stores, as do "capital breeders." Infant mortality to 1 year of age in a nondrought year is 52%, higher than infant mortality in small to medium-sized anthropoids. The oldest known female was 18 years old in 2001. We suggest that 18-20 years may represent the maximum life-span for wild ring-tailed lemurs. Because males regularly emigrate from the population, we have no data regarding male life-span; however, there is some indication that males do not survive as long as females. Group fission has occurred three times: twice from one parent group living in the driest area of the reserve, with the most dispersed food resources. We suggest that the reproductive strategy that has evolved in this species, wherein females reproduce early in life and annually until old age, is a response to the unusual climate and environmental conditions under which Lemur catta has evolved. PMID:12541335

  9. Contrasting population genetic structure among freshwater-resident and anadromous lampreys: the role of demographic history, differential dispersal and anthropogenic barriers to movement

    PubMed Central

    Bracken, Fiona S A; Hoelzel, A Rus; Hume, John B; Lucas, Martyn C

    2015-01-01

    The tendency of many species to abandon migration remains a poorly understood aspect of evolutionary biology that may play an important role in promoting species radiation by both allopatric and sympatric mechanisms. Anadromy inherently offers an opportunity for the colonization of freshwater environments, and the shift from an anadromous to a wholly freshwater life history has occurred in many families of fishes. Freshwater-resident forms have arisen repeatedly among lampreys (within the Petromyzontidae and Mordaciidae), and there has been much debate as to whether anadromous lampreys, and their derived freshwater-resident analogues, constitute distinct species or are divergent ecotypes of polymorphic species. Samples of 543 European river lamprey Lampetra fluviatilis (mostly from anadromous populations) and freshwater European brook lamprey Lampetra planeri from across 18 sites, primarily in the British Isles, were investigated for 13 polymorphic microsatellite DNA loci, and 108 samples from six of these sites were sequenced for 829 bp of mitochondrial DNA (mtDNA). We found contrasting patterns of population structure for mtDNA and microsatellite DNA markers, such that low diversity and little structure were seen for all populations for mtDNA (consistent with a recent founder expansion event), while fine-scale structuring was evident for nuclear markers. Strong differentiation for microsatellite DNA loci was seen among freshwater-resident L. planeri populations and between L. fluviatilis and L. planeri in most cases, but little structure was evident among anadromous L. fluviatilis populations. We conclude that postglacial colonization founded multiple freshwater-resident populations with strong habitat fidelity and limited dispersal tendencies that became highly differentiated, a pattern that was likely intensified by anthropogenic barriers. PMID:25689694

  10. Genetic Diversity and Demographic History of Wild and Cultivated/Naturalised Plant Populations: Evidence from Dalmatian Sage (Salvia officinalis L., Lamiaceae).

    PubMed

    Rešetnik, Ivana; Baričevič, Dea; Batîr Rusu, Diana; Carović-Stanko, Klaudija; Chatzopoulou, Paschalina; Dajić-Stevanović, Zora; Gonceariuc, Maria; Grdiša, Martina; Greguraš, Danijela; Ibraliu, Alban; Jug-Dujaković, Marija; Krasniqi, Elez; Liber, Zlatko; Murtić, Senad; Pećanac, Dragana; Radosavljević, Ivan; Stefkov, Gjoshe; Stešević, Danijela; Šoštarić, Ivan; Šatović, Zlatko

    2016-01-01

    Dalmatian sage (Salvia officinalis L., Lamiaceae) is a well-known aromatic and medicinal Mediterranean plant that is native in coastal regions of the western Balkan and southern Apennine Peninsulas and is commonly cultivated worldwide. It is widely used in the food, pharmaceutical and cosmetic industries. Knowledge of its genetic diversity and spatiotemporal patterns is important for plant breeding programmes and conservation. We used eight microsatellite markers to investigate evolutionary history of indigenous populations as well as genetic diversity and structure within and among indigenous and cultivated/naturalised populations distributed across the Balkan Peninsula. The results showed a clear separation between the indigenous and cultivated/naturalised groups, with the cultivated material originating from one restricted geographical area. Most of the genetic diversity in both groups was attributable to differences among individuals within populations, although spatial genetic analysis of indigenous populations indicated the existence of isolation by distance. Geographical structuring of indigenous populations was found using clustering analysis, with three sub-clusters of indigenous populations. The highest level of gene diversity and the greatest number of private alleles were found in the central part of the eastern Adriatic coast, while decreases in gene diversity and number of private alleles were evident towards the northwestern Adriatic coast and southern and eastern regions of the Balkan Peninsula. The results of Ecological Niche Modelling during Last Glacial Maximum and Approximate Bayesian Computation suggested two plausible evolutionary trajectories: 1) the species survived in the glacial refugium in southern Adriatic coastal region with subsequent colonization events towards northern, eastern and southern Balkan Peninsula; 2) species survived in several refugia exhibiting concurrent divergence into three genetic groups. The insight into genetic

  11. Genetic Diversity and Demographic History of Wild and Cultivated/Naturalised Plant Populations: Evidence from Dalmatian Sage (Salvia officinalis L., Lamiaceae)

    PubMed Central

    Rešetnik, Ivana; Baričevič, Dea; Batîr Rusu, Diana; Carović-Stanko, Klaudija; Chatzopoulou, Paschalina; Dajić-Stevanović, Zora; Gonceariuc, Maria; Grdiša, Martina; Greguraš, Danijela; Ibraliu, Alban; Jug-Dujaković, Marija; Krasniqi, Elez; Liber, Zlatko; Murtić, Senad; Pećanac, Dragana; Radosavljević, Ivan; Stefkov, Gjoshe; Stešević, Danijela; Šoštarić, Ivan; Šatović, Zlatko

    2016-01-01

    Dalmatian sage (Salvia officinalis L., Lamiaceae) is a well-known aromatic and medicinal Mediterranean plant that is native in coastal regions of the western Balkan and southern Apennine Peninsulas and is commonly cultivated worldwide. It is widely used in the food, pharmaceutical and cosmetic industries. Knowledge of its genetic diversity and spatiotemporal patterns is important for plant breeding programmes and conservation. We used eight microsatellite markers to investigate evolutionary history of indigenous populations as well as genetic diversity and structure within and among indigenous and cultivated/naturalised populations distributed across the Balkan Peninsula. The results showed a clear separation between the indigenous and cultivated/naturalised groups, with the cultivated material originating from one restricted geographical area. Most of the genetic diversity in both groups was attributable to differences among individuals within populations, although spatial genetic analysis of indigenous populations indicated the existence of isolation by distance. Geographical structuring of indigenous populations was found using clustering analysis, with three sub-clusters of indigenous populations. The highest level of gene diversity and the greatest number of private alleles were found in the central part of the eastern Adriatic coast, while decreases in gene diversity and number of private alleles were evident towards the northwestern Adriatic coast and southern and eastern regions of the Balkan Peninsula. The results of Ecological Niche Modelling during Last Glacial Maximum and Approximate Bayesian Computation suggested two plausible evolutionary trajectories: 1) the species survived in the glacial refugium in southern Adriatic coastal region with subsequent colonization events towards northern, eastern and southern Balkan Peninsula; 2) species survived in several refugia exhibiting concurrent divergence into three genetic groups. The insight into genetic

  12. Genetic structure and demographic history of the endangered tree species Dysoxylum malabaricum (Meliaceae) in Western Ghats, India: implications for conservation in a biodiversity hotspot.

    PubMed

    Bodare, Sofia; Tsuda, Yoshiaki; Ravikanth, Gudasalamani; Uma Shaanker, Ramanan; Lascoux, Martin

    2013-09-01

    The impact of fragmentation by human activities on genetic diversity of forest trees is an important concern in forest conservation, especially in tropical forests. Dysoxylum malabaricum (white cedar) is an economically important tree species, endemic to the Western Ghats, India, one of the world's eight most important biodiversity hotspots. As D. malabaricum is under pressure of disturbance and fragmentation together with overharvesting, conservation efforts are required in this species. In this study, range-wide genetic structure of twelve D. malabaricum populations was evaluated to assess the impact of human activities on genetic diversity and infer the species' evolutionary history, using both nuclear and chloroplast (cp) DNA simple sequence repeats (SSR). As genetic diversity and population structure did not differ among seedling, juvenile and adult age classes, reproductive success among the old-growth trees and long distance seed dispersal by hornbills were suggested to contribute to maintain genetic diversity. The fixation index (F IS) was significantly correlated with latitude, with a higher level of inbreeding in the northern populations, possibly reflecting a more severe ecosystem disturbance in those populations. Both nuclear and cpSSRs revealed northern and southern genetic groups with some discordance of their distributions; however, they did not correlate with any of the two geographic gaps known as genetic barriers to animals. Approximate Bayesian computation-based inference from nuclear SSRs suggested that population divergence occurred before the last glacial maximum. Finally we discussed the implications of these results, in particular the presence of a clear pattern of historical genetic subdivision, on conservation policies.

  13. Demographic and life-history patterns in a population of ring-tailed lemurs (Lemur catta) at Beza Mahafaly Reserve, Madagascar: a 15-year perspective.

    PubMed

    Gould, Lisa; Sussman, R W; Sauther, Michelle L

    2003-02-01

    Over 15 field seasons (1987-2001), we collected census and life-history data on a population of individually identified ring-tailed lemurs at the Beza Mahafaly Reserve, Madagascar. No significant difference was found in population size over the study period, though a marked decline in the population occurred following a 2-year drought. The population rebounded rapidly after the immediate postdrought period. There was nearly a complete replacement of individuals over the study period. Average group size is 11.5 animals, and adult male to female sex ratio is 0.92. Most females reproduce annually, and the average fecundity rate is 84.3%. The greatest variability in fecundity is found among old females. We suggest that ring-tailed lemur females follow an "income breeding" strategy, i.e., females use maximum resources during reproduction rather than relying on fat stores, as do "capital breeders." Infant mortality to 1 year of age in a nondrought year is 52%, higher than infant mortality in small to medium-sized anthropoids. The oldest known female was 18 years old in 2001. We suggest that 18-20 years may represent the maximum life-span for wild ring-tailed lemurs. Because males regularly emigrate from the population, we have no data regarding male life-span; however, there is some indication that males do not survive as long as females. Group fission has occurred three times: twice from one parent group living in the driest area of the reserve, with the most dispersed food resources. We suggest that the reproductive strategy that has evolved in this species, wherein females reproduce early in life and annually until old age, is a response to the unusual climate and environmental conditions under which Lemur catta has evolved.

  14. Genetic structure and demographic history of the endangered tree species Dysoxylum malabaricum (Meliaceae) in Western Ghats, India: implications for conservation in a biodiversity hotspot

    PubMed Central

    Bodare, Sofia; Tsuda, Yoshiaki; Ravikanth, Gudasalamani; Uma Shaanker, Ramanan; Lascoux, Martin

    2013-01-01

    The impact of fragmentation by human activities on genetic diversity of forest trees is an important concern in forest conservation, especially in tropical forests. Dysoxylum malabaricum (white cedar) is an economically important tree species, endemic to the Western Ghats, India, one of the world's eight most important biodiversity hotspots. As D. malabaricum is under pressure of disturbance and fragmentation together with overharvesting, conservation efforts are required in this species. In this study, range-wide genetic structure of twelve D. malabaricum populations was evaluated to assess the impact of human activities on genetic diversity and infer the species’ evolutionary history, using both nuclear and chloroplast (cp) DNA simple sequence repeats (SSR). As genetic diversity and population structure did not differ among seedling, juvenile and adult age classes, reproductive success among the old-growth trees and long distance seed dispersal by hornbills were suggested to contribute to maintain genetic diversity. The fixation index (FIS) was significantly correlated with latitude, with a higher level of inbreeding in the northern populations, possibly reflecting a more severe ecosystem disturbance in those populations. Both nuclear and cpSSRs revealed northern and southern genetic groups with some discordance of their distributions; however, they did not correlate with any of the two geographic gaps known as genetic barriers to animals. Approximate Bayesian computation-based inference from nuclear SSRs suggested that population divergence occurred before the last glacial maximum. Finally we discussed the implications of these results, in particular the presence of a clear pattern of historical genetic subdivision, on conservation policies. PMID:24223264

  15. Genetic Diversity and Demographic History of Wild and Cultivated/Naturalised Plant Populations: Evidence from Dalmatian Sage (Salvia officinalis L., Lamiaceae).

    PubMed

    Rešetnik, Ivana; Baričevič, Dea; Batîr Rusu, Diana; Carović-Stanko, Klaudija; Chatzopoulou, Paschalina; Dajić-Stevanović, Zora; Gonceariuc, Maria; Grdiša, Martina; Greguraš, Danijela; Ibraliu, Alban; Jug-Dujaković, Marija; Krasniqi, Elez; Liber, Zlatko; Murtić, Senad; Pećanac, Dragana; Radosavljević, Ivan; Stefkov, Gjoshe; Stešević, Danijela; Šoštarić, Ivan; Šatović, Zlatko

    2016-01-01

    Dalmatian sage (Salvia officinalis L., Lamiaceae) is a well-known aromatic and medicinal Mediterranean plant that is native in coastal regions of the western Balkan and southern Apennine Peninsulas and is commonly cultivated worldwide. It is widely used in the food, pharmaceutical and cosmetic industries. Knowledge of its genetic diversity and spatiotemporal patterns is important for plant breeding programmes and conservation. We used eight microsatellite markers to investigate evolutionary history of indigenous populations as well as genetic diversity and structure within and among indigenous and cultivated/naturalised populations distributed across the Balkan Peninsula. The results showed a clear separation between the indigenous and cultivated/naturalised groups, with the cultivated material originating from one restricted geographical area. Most of the genetic diversity in both groups was attributable to differences among individuals within populations, although spatial genetic analysis of indigenous populations indicated the existence of isolation by distance. Geographical structuring of indigenous populations was found using clustering analysis, with three sub-clusters of indigenous populations. The highest level of gene diversity and the greatest number of private alleles were found in the central part of the eastern Adriatic coast, while decreases in gene diversity and number of private alleles were evident towards the northwestern Adriatic coast and southern and eastern regions of the Balkan Peninsula. The results of Ecological Niche Modelling during Last Glacial Maximum and Approximate Bayesian Computation suggested two plausible evolutionary trajectories: 1) the species survived in the glacial refugium in southern Adriatic coastal region with subsequent colonization events towards northern, eastern and southern Balkan Peninsula; 2) species survived in several refugia exhibiting concurrent divergence into three genetic groups. The insight into genetic

  16. Contrasting population genetic structure among freshwater-resident and anadromous lampreys: the role of demographic history, differential dispersal and anthropogenic barriers to movement.

    PubMed

    Bracken, Fiona S A; Hoelzel, A Rus; Hume, John B; Lucas, Martyn C

    2015-03-01

    The tendency of many species to abandon migration remains a poorly understood aspect of evolutionary biology that may play an important role in promoting species radiation by both allopatric and sympatric mechanisms. Anadromy inherently offers an opportunity for the colonization of freshwater environments, and the shift from an anadromous to a wholly freshwater life history has occurred in many families of fishes. Freshwater-resident forms have arisen repeatedly among lampreys (within the Petromyzontidae and Mordaciidae), and there has been much debate as to whether anadromous lampreys, and their derived freshwater-resident analogues, constitute distinct species or are divergent ecotypes of polymorphic species. Samples of 543 European river lamprey Lampetra fluviatilis (mostly from anadromous populations) and freshwater European brook lamprey Lampetra planeri from across 18 sites, primarily in the British Isles, were investigated for 13 polymorphic microsatellite DNA loci, and 108 samples from six of these sites were sequenced for 829 bp of mitochondrial DNA (mtDNA). We found contrasting patterns of population structure for mtDNA and microsatellite DNA markers, such that low diversity and little structure were seen for all populations for mtDNA (consistent with a recent founder expansion event), while fine-scale structuring was evident for nuclear markers. Strong differentiation for microsatellite DNA loci was seen among freshwater-resident L. planeri populations and between L. fluviatilis and L. planeri in most cases, but little structure was evident among anadromous L. fluviatilis populations. We conclude that postglacial colonization founded multiple freshwater-resident populations with strong habitat fidelity and limited dispersal tendencies that became highly differentiated, a pattern that was likely intensified by anthropogenic barriers.

  17. Population Structure, Genetic Diversity, Effective Population Size, Demographic History and Regional Connectivity Patterns of the Endangered Dusky Grouper, Epinephelus marginatus (Teleostei: Serranidae), within Malta’s Fisheries Management Zone

    PubMed Central

    Vella, Adriana

    2016-01-01

    The objective of this study is to describe the genetic population structure and demographic history of the endangered marine fish, Epinephelus marginatus, within Malta’s Fisheries Management Zone for the purpose of localised conservation planning. Epinephelus marginatus is a long-lived, sedentary, reef-associated protogynous hermaphrodite with high commercial and recreational value that is at risk of extinction throughout its global distribution. Based on global trends, population substructuring and gaps in local knowledge this has led to an increased interest in evaluation of local stock. Assessment of Maltese demography was based on historical and contemporary catch landings data whilst genetic population structure and regional connectivity patterns were evaluated by examining 175 individuals collected within the central Mediterranean region between 2002 and 2009 using 14 nuclear microsatellite loci. Demographic stock assessment of Maltese E. marginatus’ revealed a 99% decline in catch landings between 1947 and 2009 within the Fisheries Management Zone. A contemporary modest mean size was observed, 3 ± 3 kg, where approximately 17% of the population was juvenile, 68% female/sex-changing and 15% were male with a male-to-female sex ratio of 1:5. Genetic analysis describes the overall population of E. marginatus’ within the Fisheries Management Zone as decreasing in size (ƟH = 2.2), which has gone through a significant size reduction in the past (M = 0.41) and consequently shows signs of moderate inbreeding (FIS = 0.10, p < 0.001) with an estimated effective population size of 130 individuals. Results of spatially explicit Bayesian genetic cluster analysis detected two geographically distinct subpopulations within Malta’s Fisheries Management Zone and that they are connected to a larger network of E. marginatus’ within the Sicily Channel. Results suggest conservation management should be designed to reflect E. marginatus’ within Malta’s Fisheries

  18. History of the Balkans: Eighteenth and Nineteenth Centuries. Volume 1. The Joint Committee on Eastern Europe Publications Series. No. 12.

    ERIC Educational Resources Information Center

    Jelavich, Barbara

    Designed as an introductory history, this book covers developments in the Balkan Peninsula from the 17th through the 19th centuries. Emphasis is placed on the process by which separate nationalities broke away from imperial rule, established independent states, and embarked on economic and social modernization. To establish perspective on the role…

  19. Demographics: people and markets.

    PubMed

    Merrick, T W; Tordella, S J

    1988-02-01

    The basics of demography are now basic to us business as well. Demographics combine demographic data with socioeconomic and geographic factors to help business and other managers know the market for their goods and services. This pamphlet explains market, product, and site analyses, discusses data sources and resources, and includes case studies involving major corporations. Post-war population trends have had an enormous impact on consumer and labor markets, bringing home to business the importance of taking advantage of demographic shifts. Advances in computerized access to data describing changes and increased consciousness of their economic significance has spurred the application of demographic knowledge by managers and the growth of the demographics information industry. The pamphlet describes the resources and methods of demographics including the creation and use of demographic data products. PMID:12315032

  20. Demographics: people and markets.

    PubMed

    Merrick, T W; Tordella, S J

    1988-02-01

    The basics of demography are now basic to us business as well. Demographics combine demographic data with socioeconomic and geographic factors to help business and other managers know the market for their goods and services. This pamphlet explains market, product, and site analyses, discusses data sources and resources, and includes case studies involving major corporations. Post-war population trends have had an enormous impact on consumer and labor markets, bringing home to business the importance of taking advantage of demographic shifts. Advances in computerized access to data describing changes and increased consciousness of their economic significance has spurred the application of demographic knowledge by managers and the growth of the demographics information industry. The pamphlet describes the resources and methods of demographics including the creation and use of demographic data products.

  1. Re-writing the natural history of pain and related symptoms in the joint hypermobility syndrome/Ehlers-Danlos syndrome, hypermobility type.

    PubMed

    Castori, Marco; Morlino, Silvia; Celletti, Claudia; Ghibellini, Giulia; Bruschini, Michela; Grammatico, Paola; Blundo, Carlo; Camerota, Filippo

    2013-12-01

    Joint hypermobility syndrome (JHS) and Ehlers-Danlos syndrome, hypermobility type (EDS-HT) are two clinically overlapping connective tissue disorders characterized by chronic/recurrent pain, joint instability complications, and minor skin changes. Fatigue and headache are also common, although are not yet considered diagnostic criteria. JHS/EDS-HT is a unexpectedly common condition that remains underdiagnosed by most clinicians and pain specialists. This results in interventions limited to symptomatic and non-satisfactory treatments, lacking reasonable pathophysiologic rationale. In this manuscript the fragmented knowledge on pain, fatigue, and headache in JHS/EDS is presented with review of the available published information and a description of the clinical course by symptoms, on the basis of authors' experience. Pathogenic mechanisms are suggested through comparisons with other functional somatic syndromes (e.g., chronic fatigue syndrome, fibromyalgia, and functional gastrointestinal disorders). The re-writing of the natural history of JHS/EDS-HT is aimed to raise awareness among clinical geneticists and specialists treating chronic pain conditions about pain and other complications of JHS/EDS-HT. Symptoms' clustering by disease stage is proposed to investigate both the molecular causes and the symptoms management of JHS/EDS-HT in future studies. PMID:24254847

  2. Joint effects of habitat heterogeneity and species' life-history traits on population dynamics in spatially structured landscapes.

    PubMed

    Ye, Xinping; Skidmore, Andrew K; Wang, Tiejun

    2014-01-01

    Both habitat heterogeneity and species' life-history traits play important roles in driving population dynamics, yet there is little scientific consensus around the combined effect of these two factors on populations in complex landscapes. Using a spatially explicit agent-based model, we explored how interactions between habitat spatial structure (defined here as the scale of spatial autocorrelation in habitat quality) and species life-history strategies (defined here by species environmental tolerance and movement capacity) affect population dynamics in spatially heterogeneous landscapes. We compared the responses of four hypothetical species with different life-history traits to four landscape scenarios differing in the scale of spatial autocorrelation in habitat quality. The results showed that the population size of all hypothetical species exhibited a substantial increase as the scale of spatial autocorrelation in habitat quality increased, yet the pattern of population increase was shaped by species' movement capacity. The increasing scale of spatial autocorrelation in habitat quality promoted the resource share of individuals, but had little effect on the mean mortality rate of individuals. Species' movement capacity also determined the proportion of individuals in high-quality cells as well as the proportion of individuals experiencing competition in response to increased spatial autocorrelation in habitat quality. Positive correlations between the resource share of individuals and the proportion of individuals experiencing competition indicate that large-scale spatial autocorrelation in habitat quality may mask the density-dependent effect on populations through increasing the resource share of individuals, especially for species with low mobility. These findings suggest that low-mobility species may be more sensitive to habitat spatial heterogeneity in spatially structured landscapes. In addition, localized movement in combination with spatial

  3. Evolutionary shaping of demographic schedules

    PubMed Central

    Wachter, Kenneth W.; Steinsaltz, David; Evans, Steven N.

    2014-01-01

    Evolutionary processes of natural selection may be expected to leave their mark on age patterns of survival and reproduction. Demographic theory includes three main strands—mutation accumulation, stochastic vitality, and optimal life histories. This paper reviews the three strands and, concentrating on mutation accumulation, extends a mathematical result with broad implications concerning the effect of interactions between small age-specific effects of deleterious mutant alleles. Empirical data from genomic sequencing along with prospects for combining strands of theory hold hope for future progress. PMID:25024186

  4. Dancing with Demographers.

    ERIC Educational Resources Information Center

    Robertson, Heather-Jane

    2000-01-01

    Demographic projections concerning the shortage of teachers in Canada, their pay scale, the feminization of teaching, the gender gap in salaries, and teacher autonomy have often been incorrect, or correct for the wrong reasons. Instead of relying on demographic predictions, teachers should contemplate who they really want to be professionally,…

  5. The business of demographics.

    PubMed

    Russell, C

    1984-06-01

    The emergence of "demographics" in the past 15 years is a vital tool for American business research and planning. Tracing demographic trends became important for businesses when traditional consumer markets splintered with the enormous changes since the 1960s in US population growth, age structure, geographic distribution, income, education, living arrangements, and life-styles. The mass of reliable, small-area demographic data needed for market estimates and projections became available with the electronic census--public release of Census Bureau census and survey data on computer tape, beginning with the 1970 census. Census Bureau tapes as well as printed reports and microfiche are now widely accessible at low cost through summary tape processing centers designated by the bureau and its 12 regional offices and State Data Center Program. Data accessibility, plummeting computer costs, and businessess' unfamiliarity with demographics spawned the private data industry. By 1984, 70 private companies were offering demographic services to business clients--customized information repackaged from public data or drawn from proprietary data bases created from such data. Critics protest the for-profit use of public data by companies able to afford expensive mainframe computer technology. Business people defend their rights to public data as taxpaying ceitzens, but they must ensure that the data are indeed used for the public good. They must also question the quality of demographic data generated by private companies. Business' demographic expertise will improve when business schools offer training in demography, as few now do, though 40 of 88 graduate-level demographic programs now include business-oriented courses. Lower cost, easier access to business demographics is growing as more census data become available on microcomputer diskettes and through on-line linkages with large data bases--from private data companies and the Census Bureau itself. A directory of private and

  6. Demographers converge on Chicago.

    PubMed

    Gardner, B; Haupt, A; Lamphere, D; Merrick, T; Dowdell, D D; Murphy, E; O'hare, B; Patriquin, W; Van Den Oever, N; Van Der Tak, J

    1987-06-01

    The Chicago annual meeting of the Population Association of America (PAA) attracted some 1100 demographers and populationists. This paper discusses some of the sessions during the meeting's week. Some of the meetings included: 1) the Association for Population/Family Planning Libraries and Information Centers - International (APLIC), and 2) a Psychosocial Workshop. Some of the sessions included: 1) Nonmarital Sexuality and Fertility in the Third World, 2) Acceptability of New Contraceptive Methods, 3) Family Change in Western Countries, 4) Social Policy in Aging Populations, 5) The Future of Marriage, 6) Computers, 7) USSR, 8) AIDS, and 9) Women's Caucus. Some of the themes included: 1) Demographers in the Courtroom, and 2) Applied Demographers.

  7. Population Bulletin. Pakistan: A Demographic Report.

    ERIC Educational Resources Information Center

    Population Reference Bureau, Inc., Washington, DC.

    This report presents a brief history of Pakistan as a nation and reviews a number of demographic variables. Major topics discussed are population growth and shifts, urbanization, and labor characteristics and problems. Based on this information and projections, the report concludes with a discussion of the failure of family planning programs and…

  8. Genetic demographic networks: Mathematical model and applications.

    PubMed

    Kimmel, Marek; Wojdyła, Tomasz

    2016-10-01

    Recent improvement in the quality of genetic data obtained from extinct human populations and their ancestors encourages searching for answers to basic questions regarding human population history. The most common and successful are model-based approaches, in which genetic data are compared to the data obtained from the assumed demography model. Using such approach, it is possible to either validate or adjust assumed demography. Model fit to data can be obtained based on reverse-time coalescent simulations or forward-time simulations. In this paper we introduce a computational method based on mathematical equation that allows obtaining joint distributions of pairs of individuals under a specified demography model, each of them characterized by a genetic variant at a chosen locus. The two individuals are randomly sampled from either the same or two different populations. The model assumes three types of demographic events (split, merge and migration). Populations evolve according to the time-continuous Moran model with drift and Markov-process mutation. This latter process is described by the Lyapunov-type equation introduced by O'Brien and generalized in our previous works. Application of this equation constitutes an original contribution. In the result section of the paper we present sample applications of our model to both simulated and literature-based demographies. Among other we include a study of the Slavs-Balts-Finns genetic relationship, in which we model split and migrations between the Balts and Slavs. We also include another example that involves the migration rates between farmers and hunters-gatherers, based on modern and ancient DNA samples. This latter process was previously studied using coalescent simulations. Our results are in general agreement with the previous method, which provides validation of our approach. Although our model is not an alternative to simulation methods in the practical sense, it provides an algorithm to compute pairwise

  9. Joint swelling

    MedlinePlus

    Swelling of a joint ... Joint swelling may occur along with joint pain . The swelling may cause the joint to appear larger or abnormally shaped. Joint swelling can cause pain or stiffness. After an ...

  10. Demographic changes and nationalism.

    PubMed

    Vishnevskii, A G

    1995-01-01

    This article examines the different characteristics of the many peoples inhabiting what used to be the Soviet Union and communist Eastern Europe, including Yugoslavia. The differences among these nationalities, or ethnic groups, are illustrated using the example of demographic modernization, showing how different peoples have or have not passed through the demographic transition process. The author looks at ethnic differences in mortality, fertility, natural increase, and migration, as well as economic and social inequalities among ethnic groups. The prospects for inter-ethnic conflict are assessed.

  11. KSC History Project

    NASA Technical Reports Server (NTRS)

    Dethloff, Henry C.

    2001-01-01

    The KSC History Project focuses on archival research and oral history interviews on the history of Kennedy Space Center (KSC). Related projects include the preparation of a precis and chapter outline for a proposed book-length narrative history, a bibliography of key primary and secondary resources, a brief monograph overview of the history of KSC, and a monograph on the history of safety at the Center. Finally, there is work on the development of a web page and a personal history data base associated with the oral history project. The KSC History Project has been a joint endeavor between Henry C. Dethloff and Dr. Noble Lee Snaples, Jr.

  12. China's demographic dilemmas.

    PubMed

    Tien, H Y; Zhang, T; Ping, Y; Li, J; Liang, Z

    1992-06-01

    China's demographic dilemmas are discussed as the demographic surge during the 20th century, the demographic transition, the struggle to regulate fertility, population and development, and prospects for the future. Brief accounts are given of China's household registration system and the efforts in entry into the global economy. There are references, suggested readings, and discussion questions. Ample figures and tables express population growth, birth and death rates, fertility, sex ratios, population projections for these older than 65 and total population, contraception (IUDs, sterilizations, and abortions), abortion ratios, ethnic minority groups, provincial population data for 1990, schools and enrollment, health care resources, selected economic indicators, and availability of selected consumer items (sewing machines, watches, bicycles, electric fans, washers, refrigerators, televisions, radios, and cameras). Population planning has been successful in reducing the birth rate from 35/1000 in the 1950s to 20/1000 in the 1990s. 17 million persons are added annually. The projection for 2000 is 1.3 billion persons. The emphasis of the discussion is on the development and consequences of strict population planning control measures instituted in the 1970s and strengthened in the 1980s. In addition to curbing numbers, the measures have also led to a rapid aging of the population, a marriage squeeze, charges of female infanticide, and international censure. Population pressure is felt in urban areas, and in the labor force, education, and health systems. Industrialization has led to serious deterioration of natural resources. The gap between rural and urban population has widened.

  13. Genetic demographic networks: Mathematical model and applications.

    PubMed

    Kimmel, Marek; Wojdyła, Tomasz

    2016-10-01

    Recent improvement in the quality of genetic data obtained from extinct human populations and their ancestors encourages searching for answers to basic questions regarding human population history. The most common and successful are model-based approaches, in which genetic data are compared to the data obtained from the assumed demography model. Using such approach, it is possible to either validate or adjust assumed demography. Model fit to data can be obtained based on reverse-time coalescent simulations or forward-time simulations. In this paper we introduce a computational method based on mathematical equation that allows obtaining joint distributions of pairs of individuals under a specified demography model, each of them characterized by a genetic variant at a chosen locus. The two individuals are randomly sampled from either the same or two different populations. The model assumes three types of demographic events (split, merge and migration). Populations evolve according to the time-continuous Moran model with drift and Markov-process mutation. This latter process is described by the Lyapunov-type equation introduced by O'Brien and generalized in our previous works. Application of this equation constitutes an original contribution. In the result section of the paper we present sample applications of our model to both simulated and literature-based demographies. Among other we include a study of the Slavs-Balts-Finns genetic relationship, in which we model split and migrations between the Balts and Slavs. We also include another example that involves the migration rates between farmers and hunters-gatherers, based on modern and ancient DNA samples. This latter process was previously studied using coalescent simulations. Our results are in general agreement with the previous method, which provides validation of our approach. Although our model is not an alternative to simulation methods in the practical sense, it provides an algorithm to compute pairwise

  14. Building demographic literacy.

    PubMed

    Crews, K

    1993-01-01

    Students should get in the habit of seeking out the most current projections, estimates, or rates available. Since demographic measures change over time, publications based on the UN's world population projections from 1980 or 1990 may need to be supplemented using the UN's most current, 1992, projections. A 1989 Census Bureau report on the African American Population will not contain data from the 1990 Census or the 1992 Current Population Survey, conducted by the Census Bureau. Some groups collect data with advocacy in mind, as shown by the range of estimates of participants at the 1993 National March on Washington for Lesbian, Gay and Bi Equal Rights and Liberation. The organizers estimated that 1 million people participated; the US Park Police estimated 300,000; and the Washington Blade, a gay newspaper, reported 750,000. A seemingly innocuous choice of phrasing can change the meaning of demographic data. One commonly misreported concept is population doubling time which is not a prediction, but rather a concept designed to accent how fast a population is growing at the present time. At current rates, the population of India would double in size in 34 years, but it is more likely that growth rates will begin to slow down somewhat during that time. Older students may be encouraged to examine the assumptions behind population projections. The UN's long-range projection that world population will grow to 10 billion by 2050 is based on certain assumption about fertility and mortality during the period. With regard to the fastest growing US minority, Hispanics added the largest number of people to the US population during the 1980s, but Asians had the largest percent increase. The time to initiate demographic literacy is in the early grades of school.

  15. Communicating demographic trends.

    PubMed

    Merrick, T W

    1993-01-01

    The remarks reported were originally directed to an audience of graduate students from developing countries studying population policy communications. The goal of communicating to policymakers is to place research results in a context of policy or program decision in a specific time and place. Important surveys are conducted and results need to be communicated to policymakers, i.e., the Demographic and Health Survey, the Contraceptive Prevalence surveys, and the World Fertility Survey. It is important to know who the audience is, what the issues are, the key policy players, the major concerns and views of key policymakers, the message, the channel for communication, and the method of evaluation of success in communicating the message. Newspapers and mass media are useful sources. Oversimplification or unsubstantiated positions will backfire. The standard is for technical scrutiny and understandability by a nontechnical audience. Judgment in selecting appropriate facts is essential. In explaining a complex relationship between education and fertility in a hypothetical study while at the same reporting the conclusion that more money needs to be spent on education leaves the reader confused. Be wary of reporting unsubstantiated recommendations. Demography sometimes can only provide the underpinnings even on such central issues as the role population growth and the damage to the environment. It could be that environmental resources are being poorly managed which is exacerbated by population growth. Slowing population growth may not change the outcome, but may minimize it. The context can be provided with a demographic perspective. PMID:12285783

  16. The demographic dynamics of small island societies.

    PubMed

    Cruz, M; D'ayala, P G; Marcus, E; Mcelroy, J L; Rossi, O

    1987-01-01

    Small islands and microstates have demonstrated a unique demographic pattern, including cycles of swift population increases or decreases well beyond natural birth and death rate balances. These demographic fluctuations have been produced largely by rises or declines in market opportunities. The process of taking advantage of favorable opportunities is always followed by a specialization in the given activity, without regard to environmental protection issues or a longterm strategy for economic development and resource diversification. The population growth phase is associated with increasing fragility of the economic base, whether because of the external dangers of overspecialization or induced internal dysfunctions such as disease and resource depletion. Eventually complete collapse results, causing chronic outmigration or even depopulation. Case histories of maritime basins in the Mediterranean, Caribbean, and Pacific show that the demographic structure of small islands has been particularly sensitive to changing economic opportunities, the vagaries of market forces, and cataclysmic natural events. Experience in these areas suggests that balanced economic development of small islands should be based on diversification of activities, thus ensuring a relatively stable pattern of growth, sound environmental management, and control of dangerous demographic fluctuations. Special attention should be given to the development of broad-based research and cooperation to integrate specific island opportunities within a regional network.

  17. [Approach to joint effusion].

    PubMed

    Henniger, M; Rehart, S

    2016-09-01

    The fundamental components of the differential diagnostics of joint effusions are the patient history and clinical examination. In the case of unclear findings, arthrosonography can provide information for the distinction between intra-articular and extra-articular pathologies. In atraumatic joint effusions inflammatory parameters in blood are determined in order to differentiate between systemic inflammatory and local inflammatory joint effusions. In the case of normal values further diagnostics are carried out using imaging. With elevated inflammatory parameters the main differential diagnoses are gouty arthritis, autoimmune joint processes and septic arthritis. When in doubt, a joint aspiration and synovial fluid analysis should be performed to rule out septic arthritis or if necessary confirmation of gouty arthritis. PMID:27562127

  18. Demographic estimates and projections.

    PubMed

    El-badry, M A; Kono, S

    1986-01-01

    The periodic assessment of global population growth from the past to the future has been one of the UN's most important contributions to member states and many other users. Available data and applicable analysis and projection methods were very limited in 1947, when the 1st global population estimates and projections were attempted. The 1st contributions of the Commission were manuals for these functions. Throughout the 1950s, 4 regional reports on Central and South America; Southeast Asia; and Asia and the far East were published. UN studies during this period tended to group regions by their position on a continuum of the demographic transition. Rough but alarming projections of population growth appeared. Projection technics were refined and standardized in the 1960s, and the demand grew for more specialized technics, e.g. dealing with urban/rural populations; the labor force; and other elements. The availability of computer technology at the end of the decade multiplied the projection capabilities, and the total population projections for the future were larger than ever. The 1970s projections, based on the more accurate and widely covered baseline data which had become available in developing countries, were also aided by more powerful and innovative indirect estimation technics; better software, and computers with larger capacities. By 1982, only a few countries were left with a total lack of data. A revision of estimates and projections is now undertaken biennially, incorporating the latest available data, utilizing advanced analytical methods and computer technology. Methodological manuals have been produced as the by-product of the revisions. UN demographic estimates and projections could be further improved by injection of a probabilistic element and the inclusion of economic factors. Roles for the future include maintenance of regional and interregional comparability of assumptions.

  19. KSC History Project

    NASA Technical Reports Server (NTRS)

    Snaples, Lee

    2001-01-01

    The project is a joint endeavor between Dr. Henry Dethloff and myself and is producing a number of products related to KSC history. This report is a summary of those projects. First, there is an overview monograph covering KSC history. Second, there is a chapter outline for an eventual book-length history. Third, there is monograph on safety at KSC. Finally, there is a web page and database dedicated to the KSC oral history project.

  20. Demographic Trends in Social Work over a Quarter-Century in an Increasingly Female Profession

    ERIC Educational Resources Information Center

    Schilling, Robert; Morrish, Jennifer Naranjo; Liu, Gan

    2008-01-01

    This article depicts the changing demographic portrait of social work education in the United States from 1974 through 2000 and considers the demographic shifts in the profession of social work. During this period, BSW and joint MSW-BSW programs increased from 150 to 404, MSW programs increased from 79 to 139, and social work doctoral programs…

  1. Demographics of Planetary Science

    NASA Astrophysics Data System (ADS)

    Bagenal, F.; White, S.

    2011-10-01

    A survey was sent out to university departments around the US that were thought to include faculty involved in planetary science research and/or offer planetary science undergraduate or graduate degrees. This is Part A of a study of the demographics of planetary science carried out by the American Institute of Physics (AIP) and sponsored by NASA's Planetary Science Division. Part B will be a survey of the planetary scientists with PhDs working in the US, to be carried out by the AIP in mid-2011. Starting on December 8th 2010 surveys were sent out by email to department chairs. A total of 48 departments responded between December 9th and April 8th . There is only U of Arizona that has a department that is called planetary sciences - the rest are combined with Earth sciences (14), astronomy (15), geology/geophysics (8), physics (7), atmospheric science (5), something else or combinations thereof. We present statistics from these 48 departments on faculty, researchers, graduate and undergraduate students.

  2. Planet Demographics from Transits

    NASA Astrophysics Data System (ADS)

    Howard, Andrew

    2015-08-01

    From the demographics of planets detected by the Kepler mission, we have learned that there exists approximately one planet per star for planets larger than Earth orbiting inside of 1 AU. We have also learned the relative occurrence of these planets as a function of their orbital periods, sizes, and host star masses and metallicities. In this talk I will review the key statistical findings that the planet size distribution peaks in the range 1-3 times Earth-size, the orbital period distribution is characterized by a power-law cut off at short periods, small planets are more prevalent around small stars, and that approximately 20% of Sun-like stars hosts a planet 1-2 times Earth-size in a habitable zone. Looking forward, I will describe analysis of photometry from the K2 mission that is yielding initial planet discoveries and offering the opportunity to measure planet occurrence in widely separated regions of the galaxy. Finally, I will also discuss recent techniques to discover transiting planets in space-based photometry and to infer planet population properties from the ensemble of detected and non-detected transit signals.

  3. [Diagnosis. History and physical examination].

    PubMed

    Pérez Martín, Álvaro

    2014-01-01

    Family physicians play a key role in the diagnosis and management of patients with osteoarthritis. Diagnosis is mainly clinical and radiological. A complete history should be taken with meticulous physical examination of the joints. The history-taking should aim to detect risk factors and compatible clinical symptoms. Pain characteristics should be identified, distinguishing between mechanical and inflammatory pain, and an exhaustive examination of the joints should be performed, with evaluation of the presence of pain, deformity, mobility restrictions (both active and passive), crepitus, joint effusion, and inflammation. A differential diagnosis should be made with all diseases that affect the joints and/or produce joint stiffness.

  4. Demographic Trends: Impact on Schools

    ERIC Educational Resources Information Center

    Chong, Sylvia N. Y.; Cheah, Horn Mun

    2010-01-01

    Background: Singapore is experiencing great demographic change. These demographic trends show fewer young people and declining birth rates, greater longevity for ageing generations and an increase in the number of non-Singaporean residents. Statistics also show that more than half of the total population increase in the last decades was…

  5. [Demographic profile of Venezuela].

    PubMed

    Quintero, I

    1984-04-01

    Sources of demographic data for Venezuela include 11 population censuses conducted between 1873-1981, birth and death registration statistics, and the household sample survey. The average annual rate of population growth increase from 2.8% between 1920-40 to 3-4% thereafter. The population at the 1961 census was 7.52 million. According to preliminary data from the 1981 census, the population of 14.57 million is growing at an annual rate of 2.8%. 41.2% of the population is under 15 years old, implying a huge demand for educational and health services, housing and employment. The dependency rate in 1980 was 81.3% for the country as a whole, 100.4% in rural areas, and 76.0% in urban areas. The young age structure means that the population will continue to grow even if natality rates decline. The crude natality rate was estimated at 47.3/1000 for 1950-55, 36.0 for 1970-75, and 32.9 for 1980-85. Some rural areas still have natality rates of over 47/1000. The total fertility rate declined from 6.5 in 1950-55 to 4.1 in 1980-85. The decline in the natality rate reflects improving quality of life, availability of family planning services, urbanization, and access of women to productive activities and educational centers. The mortality rate was 12.3/1000 in 1950-55, 9.1 in 1960-65, in 1970-75, and has been estimated at 5.5 for 1980-85. Some rural areas have mortality rates of 8.1. The infant mortality rate was 50.2/1000 in 1971 and 34.3 in 1980. Life expectancy at birth is about 69 years. During the 1920s, Venezuela unerwent expansion in infrastructure and technological utilization, generating rapid urbanization. 39.2% of the population was urban in 1941, compared to 78.8% in 1980. The significance of urbanization in Venezuela is due to the rapidity as well as the diffusion of the process. The household sample survey for the 2nd half of 1980 indicated a total of 8.16 million employed and an activity rate of 32.1% overall, 46.4% for males and 17.7% for females. The

  6. Influence of a family history of type 2 diabetes, demographic and clinical data on carotid intima-media thickness in patients with type 1 diabetes: a cross-sectional study

    PubMed Central

    2014-01-01

    Background Intima-media thickness (IMT) of the common carotid artery is a surrogate end point of cardiovascular disease (CVD). Identifying the factors associated with a higher IMT may contribute to the identification of subjects with higher CVD risk. Our objective was to compare the common carotid IMT of type 1 diabetes patients to healthy control subjects. The secondary objective was to determine factors associated with a higher carotid IMT. Methods We conducted a cross-sectional study between March 2009 and October 2013, comprising 127 type 1 diabetes patients and 125 control subjects matched by age, gender and body mass index (BMI). Carotid IMT was measured using semi-automated edge detection software. Results Type 1 diabetes patients had a higher median IMT compared with control subjects (0.538; IQR: 0.500-0.607 vs 0.513 mm; IQR: 0.481-0.557, respectively p = 0.001). Women with type 1 diabetes had a higher median IMT difference compared to the control group (0.537; IQR: 0.495-0.596 vs 0.502 mm; IQR: 0.472-0.543, respectively p = 0.003) than did men with type 1 diabetes (0.547; IQR: 0.504-0.613 vs 0.528 mm; IQR: 0.492-0.575, respectively p = 0.2). Age and diabetes duration had an additive effect on the IMT of type 1 diabetes patients. Multivariate gamma regression model analysis showed that in type 1 diabetes patients, the IMT was associated with age (Exp (β) = 1.006, p < 0.001), duration of diabetes (Exp (β) = 1.004, p = 0.001), BMI (Exp (β) = 1.005, p = 0.021), family history of type 2 diabetes (Exp (β) = 1.044, p = 0.033), total cholesterol (Exp (β) = 0.999, p = 0.001) and creatinine clearance (Exp (β) = 1.000, p = 0.043). Conclusions Patients with type 1 diabetes have increased IMT, a marker of subclinical atherosclerosis. The CVD risk may be similar between men and women with type 1 diabetes, suggesting a loss of gender protection. Also, CVD risk may be higher in those with a family

  7. Accounting for rate variation among lineages in comparative demographic analyses

    USGS Publications Warehouse

    Hope, Andrew G.; Ho, Simon Y. W.; Malaney, Jason L.; Cook, Joseph A.; Talbot, Sandra L.

    2014-01-01

    Genetic analyses of contemporary populations can be used to estimate the demographic histories of species within an ecological community. Comparison of these demographic histories can shed light on community responses to past climatic events. However, species experience different rates of molecular evolution, and this presents a major obstacle to comparative demographic analyses. We address this problem by using a Bayesian relaxed-clock method to estimate the relative evolutionary rates of 22 small mammal taxa distributed across northwestern North America. We found that estimates of the relative molecular substitution rate for each taxon were consistent across the range of sampling schemes that we compared. Using three different reference rates, we rescaled the relative rates so that they could be used to estimate absolute evolutionary timescales. Accounting for rate variation among taxa led to temporal shifts in our skyline-plot estimates of demographic history, highlighting both uniform and idiosyncratic evolutionary responses to directional climate trends for distinct ecological subsets of the small mammal community. Our approach can be used in evolutionary analyses of populations from multiple species, including comparative demographic studies.

  8. Accounting for rate variation among lineages in comparative demographic analyses.

    PubMed

    Hope, Andrew G; Ho, Simon Y W; Malaney, Jason L; Cook, Joseph A; Talbot, Sandra L

    2014-09-01

    Genetic analyses of contemporary populations can be used to estimate the demographic histories of species within an ecological community. Comparison of these demographic histories can shed light on community responses to past climatic events. However, species experience different rates of molecular evolution, and this presents a major obstacle to comparative demographic analyses. We address this problem by using a Bayesian relaxed-clock method to estimate the relative evolutionary rates of 22 small mammal taxa distributed across northwestern North America. We found that estimates of the relative molecular substitution rate for each taxon were consistent across the range of sampling schemes that we compared. Using three different reference rates, we rescaled the relative rates so that they could be used to estimate absolute evolutionary timescales. Accounting for rate variation among taxa led to temporal shifts in our skyline-plot estimates of demographic history, highlighting both uniform and idiosyncratic evolutionary responses to directional climate trends for distinct ecological subsets of the small mammal community. Our approach can be used in evolutionary analyses of populations from multiple species, including comparative demographic studies. PMID:24916007

  9. Tidal disruption event demographics

    NASA Astrophysics Data System (ADS)

    Kochanek, C. S.

    2016-09-01

    We survey the properties of stars destroyed in tidal disruption events (TDEs) as a function of black hole (BH) mass, stellar mass and evolutionary state, star formation history and redshift. For M_{BH} ≲ 10^7 M_{⊙}, the typical TDE is due to a M* ˜ 0.3 M⊙ M-dwarf, although the mass function is relatively flat for M_{ast } ≲ M_{⊙}. The contribution from older main-sequence stars and sub-giants is small but not negligible. From MBH ≃ 107.5-108.5 M⊙, the balance rapidly shifts to higher mass stars and a larger contribution from evolved stars, and is ultimately dominated by evolved stars at higher BH masses. The star formation history has little effect until the rates are dominated by evolved stars. TDE rates should decline very rapidly towards higher redshifts. The volumetric rate of TDEs is very high because the BH mass function diverges for low masses. However, any emission mechanism which is largely Eddington-limited for low BH masses suppresses this divergence in any observed sample and leads to TDE samples dominated by MBH ≃ 106.0-107.5 M⊙ BHs with roughly Eddington peak accretion rates. The typical fall-back time is relatively long, with 16 per cent having tfb < 10-1 yr (37 d), and 84 per cent having longer time-scales. Many residual rate discrepancies can be explained if surveys are biased against TDEs with these longer tfb, which seems very plausible if tfb has any relation to the transient rise time. For almost any BH mass function, systematic searches for fainter, faster time-scale TDEs in smaller galaxies, and longer time-scale TDEs in more massive galaxies are likely to be rewarded.

  10. Joint Disorders

    MedlinePlus

    A joint is where two or more bones come together, like the knee, hip, elbow, or shoulder. Joints can be damaged by many types of injuries or diseases, including Arthritis - inflammation of a joint. It causes pain, stiffness, and swelling. Over time, ...

  11. Joint impact of physical activity and family history on the development of diabetes among urban adults in Mainland China: a pooled analysis of community-based prospective cohort studies.

    PubMed

    Xu, Fei; Wang, Youfa; Ware, Robert S; Tse, Lap Ah; Wang, Zhiyong; Hong, Xin; Dunstan, David W; Owen, Neville

    2015-03-01

    To examine the joint influences of physical activity (PA) and family history (FH) of diabetes on subsequent type 2 diabetes (T2D), the authors pooled and analyzed data from 2 community-based urban adult prospective cohort studies in 2011 in Nanjing, China. Among 4550 urban participants, the 3-year cumulative incidence of T2D was 5.1%. After adjustment for potential confounders, compared with those with FH+ and insufficient PA, the adjusted odds ratio (95% confidence interval) of developing T2D was 0.42 (0.18, 0.98) for participants with sufficient PA and FH+, 0.32 (0.22, 0.46) for participants with insufficient PA and FH-, and 0.15 (0.08, 0.28) for participants with sufficient PA and FH-. Such significant graduated associations between PA/FH and risk of developing T2D were also identified in either men or women, separately. Sufficient PA and FH- may jointly reduce the risk of developing T2D in urban Chinese adults.

  12. DEMOGRAPHIC FACTORS IN THE INTEGRATION OF THE NEGRO.

    ERIC Educational Resources Information Center

    HAUSER, PHILIP M.

    DEMOGRAPHIC FACTORS HAVE HAD NEGATIVE RATHER THAN POSITIVE EFFECTS ON INTEGRATION (DEFINED HERE AS A KIND OF ACCULTURATION). THE POPULATION HISTORY OF THE NEGRO INDICATES THAT (1) SINCE 1910 THE NEGRO POPULATION HAS GROWN ENORMOUSLY, (2) NEGROES HAVE BEEN REDISTRIBUTED INTO THE NORTHERN AND WESTERN URBAN AREAS, (3) THEY HAVE REMAINED LARGELY IN…

  13. Joint effects of density and a growth inhibitor on the life history and population growth rate of the midge Chironomus riparius.

    PubMed

    Hooper, Helen L; Sibly, Richard M; Hutchinson, Thomas H; Maund, Stephen J

    2005-05-01

    Results of previous laboratory studies suggest that high population density often buffers the effects of chemical stressors that predominately increase mortality. Mortality stressors act to release more resources for the survivors and, therefore, produce less-than-additive effects. By contrast, growth stressors are expected to have opposite results or more-than-additive effects. We investigated the effects of a growth inhibitor (lufenuron) on larval growth and survival of Chironomus riparius and examined its joint effects with density on population growth rate (PGR). Exposure to 60 microg/kg sediment or greater inhibited larval growth, and exposure to 88 microg/kg or greater often resulted in mortality before reaching emergence. The effects of lufenuron, however, differed with population density. At 88 microg/kg, mortalities and, to a lesser extent, reduced fecundity resulted in a reduction in PGR at low density. Conversely, when populations were initiated at high density, PGR was similar to that of controls, because the few survivors reached maturity sooner and started producing offspring earlier. The effect of density as a growth stressor therefore was stronger than the effect of lufenuron, which had effects similar to those of a mortality stressor and produced less-than-additive effects. Long-term studies under field conditions, however, are needed before less-than-additive effects are considered to be the norm. PMID:16110992

  14. Memory Specificity and Mindfulness Jointly Moderate the Effect of Reflective Pondering on Depressive Symptoms in Individuals With a History of Recurrent Depression

    PubMed Central

    2015-01-01

    In previously depressed individuals, reflective thinking may easily get derailed and lead to detrimental effects. This study investigated the conditions in which such thinking is, or is not, adaptive. Levels of mindfulness and autobiographical memory specificity were assessed as potential moderators of the relationship between reflective thinking and depressive symptoms. Two hundred seventy-four individuals with a history of three or more previous episodes of depression completed self-report measures of depressive symptoms, rumination—including subscales for reflection and brooding—and mindfulness, as well as an autobiographical memory task to assess memory specificity. In those low in both mindfulness and memory specificity, higher levels of reflection were related to more depressive symptoms, whereas in all other groups higher levels of reflection were related to fewer depressive symptoms. The results demonstrate that the relation between reflective pondering and depressive symptoms varies depending on individual state or trait factors. In previously depressed individuals, the cognitive problem-solving aspect of reflection may be easily hampered when tendencies toward unspecific processing are increased, and awareness of mental processes such as self-judgment and reactivity is decreased. PMID:25643201

  15. Rupture history of the 2008 Mw 7.9 Wenchuan, China, earthquake: Evaluation of separate and joint inversions of geodetic, teleseismic, and strong-motion data

    USGS Publications Warehouse

    Hartzell, Stephen; Mendoza, Carlos; Ramírez-Guzmán, Leonardo; Zeng, Yuesha; Mooney, Walter

    2013-01-01

    An extensive data set of teleseismic and strong-motion waveforms and geodetic offsets is used to study the rupture history of the 2008 Wenchuan, China, earthquake. A linear multiple-time-window approach is used to parameterize the rupture. Because of the complexity of the Wenchuan faulting, three separate planes are used to represent the rupturing surfaces. This earthquake clearly demonstrates the strengths and limitations of geodetic, teleseismic, and strong-motion data sets. Geodetic data (static offsets) are valuable for determining the distribution of shallower slip but are insensitive to deeper faulting and reveal nothing about the timing of slip. Teleseismic data in the distance range 30°–90° generally involve no modeling difficulties because of simple ray paths and can distinguish shallow from deep slip. Teleseismic data, however, cannot distinguish between different slip scenarios when multiple fault planes are involved because steep takeoff angles lead to ambiguity in timing. Local strong-motion data, on the other hand, are ideal for determining the direction of rupture from directivity but can easily be over modeled with inaccurate Green’s functions, leading to misinterpretation of the slip distribution. We show that all three data sets are required to give an accurate description of the Wenchuan rupture. The moment is estimated to be approximately 1.0 × 1021 N · m with the slip characterized by multiple large patches with slips up to 10 m. Rupture initiates on the southern end of the Pengguan fault and proceeds unilaterally to the northeast. Upon reaching the cross-cutting Xiaoyudong fault, rupture of the adjacent Beichuan fault starts at this juncture and proceeds bilaterally to the northeast and southwest.

  16. [The demographic potential of Russia].

    PubMed

    Vishnevskii, A

    1998-05-01

    This is a general review of current demographic trends in Russia. The author analyzes the decline in population size that is taking place at the end of the twentieth century, and traces its origins as far back as the disturbances associated with World War I, the Communist revolution, and the civil war that followed it. Political repression during the Stalinist period and the tribulations experienced during World War II also contributed to the current demographic crisis. The author discusses the changes in migration patterns and the declining fertility and increasing mortality rates. The decline in life expectancy is also addressed. Some comparisons are made with the demographic situation in other European countries. PMID:12322045

  17. Ceramic joints

    DOEpatents

    Miller, Bradley J.; Patten, Jr., Donald O.

    1991-01-01

    Butt joints between materials having different coefficients of thermal expansion are prepared having a reduced probability of failure of stress facture. This is accomplished by narrowing/tapering the material having the lower coefficient of thermal expansion in a direction away from the joint interface and not joining the narrow-tapered surface to the material having the higher coefficient of thermal expansion.

  18. [The Arabian Peninsula: demographic surprises].

    PubMed

    Courbage, Y

    1994-01-01

    A review of current demographic trends in the countries of the Arabian Peninsula is presented, based on a number of recent surveys of child health carried out in the early 1990s. Considerable diversity is noted among the countries examined in both demographic trends and levels of socioeconomic development. However, the status of women appears to be more advanced throughout the region than in most other Muslim countries, which could indicate that a reduction in fertility is probable. The author notes a general decline in oil revenues, accompanied by a decline in fertility, throughout the region.

  19. Incidence and Demographics of Childhood Ptosis

    PubMed Central

    Griepentrog, Gregory J.; Diehl, Nancy; Mohney, Brian G.

    2012-01-01

    Purpose To report the incidence and demographics of childhood ptosis diagnosed over a 40-year period in a well-defined population. Design Retrospective, population-based cohort study. Participants Patients (< 19 years) diagnosed with childhood ptosis as residents of Olmsted County, Minnesota, from January 1, 1965, through December 31, 2004 Methods The medical records of all potential patients identified by the Rochester Epidemiology Project were reviewed. Main Outcome Measures Calculated annual age- and sex-specific incidence rates and demographic information. Results A total of 107 children were diagnosed with ptosis during the 40-year period, yielding an incidence of 7.9/100,000 < 19 years (95% confidence interval [CI]: 6.4-9.5) of age. Ninety-six (89.7%) of the 107 were congenital in onset, 81 (75%) of which had simple congenital ptosis, yielding a birth prevalence of 1 in 842 births. A family history of childhood ptosis was present in twelve percent of queried patients with simple congenital ptosis. Three (4%) of the simple congenital ptosis cases were bilateral and 55 (68%) of the unilateral cases involved the left upper eyelid (95% CI: 57%-78%, p<0.001). Conclusion Childhood ptosis was diagnosed in 7.9 per 100,000 patients less than 19 years (95% CI: 6.4-9.5). Simple congenital ptosis was the most prevalent form, occurring in 1 in 842 births, and significantly more likely to involve the left side. PMID:21496927

  20. Anaerobic prosthetic joint infection.

    PubMed

    Shah, Neel B; Tande, Aaron J; Patel, Robin; Berbari, Elie F

    2015-12-01

    In an effort to improve mobility and alleviate pain from degenerative and connective tissue joint disease, an increasing number of individuals are undergoing prosthetic joint replacement in the United States. Joint replacement is a highly effective intervention, resulting in improved quality of life and increased independence [1]. By 2030, it is predicted that approximately 4 million total hip and knee arthroplasties will be performed yearly in the United States [2]. One of the major complications associated with this procedure is prosthetic joint infection (PJI), occurring at a rate of 1-2% [3-7]. In 2011, the Musculoskeletal Infectious Society created a unifying definition for prosthetic joint infection [8]. The following year, the Infectious Disease Society of America published practice guidelines that focused on the diagnosis and management of PJI. These guidelines focused on the management of commonly encountered organisms associated with PJI, including staphylococci, streptococci and select aerobic Gram-negative bacteria. However, with the exception of Propionibacterium acnes, management of other anaerobic organisms was not addressed in these guidelines [1]. Although making up approximately 3-6% of PJI [9,10], anaerobic microorganisms cause devastating complications, and similar to the more common organisms associated with PJI, these bacteria also result in significant morbidity, poor outcomes and increased health-care costs. Data on diagnosis and management of anaerobic PJI is mostly derived from case reports, along with a few cohort studies [3]. There is a paucity of published data outlining factors associated with risks, diagnosis and management of anaerobic PJI. We therefore reviewed available literature on anaerobic PJI by systematically searching the PubMed database, and collected data from secondary searches to determine information on pathogenesis, demographic data, clinical features, diagnosis and management. We focused our search on five commonly

  1. Temporomandibular Joint, Closed

    MedlinePlus

    ... Oral Health > The Temporomandibular Joint, Closed The Temporomandibular Joint, Closed Main Content Title: The Temporomandibular Joint, Closed Description: The temporomandibular joint connects the lower ...

  2. Enrollment Management: Demographic Changes. Report.

    ERIC Educational Resources Information Center

    Gribbons, Barry C.; Meuschke, Daylene M.

    The Office of Institutional Development and Technology and the Public Information Office created this report that identifies several topics of research in order to inform marketing efforts associated with enrollment management. The report is based upon demographic studies done at the College of Canyons to measure things such as changes in the size…

  3. Are Demographics the Nation's Destiny?

    ERIC Educational Resources Information Center

    Glass, Gene V.

    2008-01-01

    In this article, the author discusses the demographic trends affecting America's public schools. As an expert on empirical evaluation of education, the author believes the major debates over vouchers, charter schools, bilingual education, and other issues are not really about preparing the next generation to compete with China or India, or about…

  4. Demographic Modelling in Weed Biocontrol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Demographic matrix modeling of plant populations can be a powerful tool to identify key life stage transitions that contribute the most to population growth of an invasive plant and hence should be targeted for disruption. Therefore, this approach has the potential to guide the pre-release selection...

  5. Compliant joint

    NASA Technical Reports Server (NTRS)

    Eklund, Wayne D. (Inventor); Kerley, James J. (Inventor)

    1990-01-01

    A compliant joint is provided for prosthetic and robotic devices which permits rotation in three different planes. The joint provides for the controlled use of cable under motion. Perpendicular outer mounting frames are joined by swaged cables that interlock at a center block. Ball bearings allow for the free rotation of the second mounting frame relative to the first mounting frame within a predetermined angular rotation that is controlled by two stop devices. The cables allow for compliance at the stops and the cables allow for compliance in six degrees of freedom enabling the duplication or simulation of the rotational movement and flexibility of a natural hip or knee joint, as well as the simulation of a joint designed for a specific robotic component for predetermined design parameters.

  6. Joint Commission

    MedlinePlus

    ... Sunday 1:00 CST, November 6, 2016 Workplace Violence Prevention Resources The Joint Commission has launched “Workplace Violence Prevention Resources,” an online resource center dedicated to ...

  7. Joint Problems

    MedlinePlus

    ... ankles and toes. Other types of arthritis include gout or pseudogout. Sometimes, there is a mechanical problem ... for more information on osteoarthritis, rheumatoid arthritis and gout. How Common are Joint Problems? Osteoarthritis, which affects ...

  8. War and the demographic trap.

    PubMed

    Last, J M

    1993-08-28

    Advice is offered on alleviating environmental damage and the suffering of women and children from the effects of war. It is postured that the demographic trap, which was described by King and Elliott, is responsible for environmental stress and many wars. The surface cause may be identified as ideology, politics, or ethnicity, but as in the case of Bosnia, the "ethnic cleansing" makes farmland available to sustain expanding Serbian or Croatian populations. If the land is environmentally damaged by war, then there is little hope of sustainable development. Conflicts in many countries have driven people to urban areas or periurban slums because of displacement and the failure of subsistence economics. Mortality from wars has reached more than a 100 million since the early 1990s. A comparable number have died indirectly from famine and disease associated with the disruption of agriculture and infrastructure from wars. Since 1945, 66-75% of mortality victims have been civilians, of whom 15 million have been women and children. In 1993, there were at least 30 conflicts ongoing throughout the world. Not all of these conflicts are as "ferocious" as the Bosnian conflict, but these "so called low intensity wars" nonetheless disrupt and kill. The manifestations of the demographic trap can be alleviated through interventions that focus on multisectoral aid and conflict resolution. There must be a cooperative effort on the part of health workers, agricultural scientists, mediators, and development personnel. Unfortunately, the amount of development assistance from Europe and America has been reduced in recent years. The recession has affected the provision of international aid. African nations, in particular, have been affected, yet these countries remain the neediest in the world. It would appear that aid agencies have given up hope that the demographic trap can be closed. Population growth must be limited, as the only hope for relieving environmental stress, ecological

  9. Demographic estimation methods for plants with dormancy

    USGS Publications Warehouse

    Kery, M.; Gregg, K.B.

    2004-01-01

    Demographic studies in plants appear simple because unlike animals, plants do not run away. Plant individuals can be marked with, e.g., plastic tags, but often the coordinates of an individual may be sufficient to identify it. Vascular plants in temperate latitudes have a pronounced seasonal life–cycle, so most plant demographers survey their study plots once a year often during or shortly after flowering. Life–states are pervasive in plants, hence the results of a demographic study for an individual can be summarized in a familiar encounter history, such as 0VFVVF000. A zero means that an individual was not seen in a year and a letter denotes its state for years when it was seen aboveground. V and F here stand for vegetative and flowering states, respectively. Probabilities of survival and state transitions can then be obtained by mere counting.Problems arise when there is an unobservable dormant state, i.e., when plants may stay belowground for one or more growing seasons. Encounter histories such as 0VF00F000 may then occur where the meaning of zeroes becomes ambiguous. A zero can either mean a dead or a dormant plant. Various ad hoc methods in wide use among plant ecologists have made strong assumptions about when a zero should be equated to a dormant individual. These methods have never been compared among each other. In our talk and in Kéry et al. (submitted), we show that these ad hoc estimators provide spurious estimates of survival and should not be used.In contrast, if detection probabilities for aboveground plants are known or can be estimated, capturerecapture (CR) models can be used to estimate probabilities of survival and state–transitions and the fraction of the population that is dormant. We have used this approach in two studies of terrestrial orchids, Cleistes bifaria (Kéry et al., submitted) and Cypripedium reginae(Kéry & Gregg, submitted) in West Virginia, U.S.A. For Cleistes, our data comprised one population with a total of 620

  10. Demographics features, clinical findings and functional status in a group of subjects with cervical myofascial pain syndrome.

    PubMed

    Sahin, Nilay; Karataş, Omer; Ozkaya, Murat; Cakmak, Ayşegül; Berker, Ender

    2008-07-01

    Subjects with myofascial pain of muscles of the neck region may present with various clinical symptoms. The aim of this study was to explore the demographics features, clinical findings and functional status in a group of patients presenting with myofascial pain of the cervical muscles. 94 cervical myofascial pain syndrome patients were recruited from the out-patient clinic. Evaluated of patient short form health survey (SF-36), pain, depression, patient demographics and physical examinations. Outcome measures; SF-36 Health Survey, visual analog scale, Beck Depression Inventory, history, physical examination. A total of 82 patients with a diagnosis of cervical myofascial syndrome were included in the study. All patients were in the young age group 37.4+/-9, and 87.8% were females. 53.1% had trigger points in the trapezius muscle with high percentage of autonomic phenomena like skin reddening, lacrimation, tinnitus and vertigo. 58.5% of the series had suffered from former cervical trauma and 40.2% also had fibromyalgia syndrome and 18.5% had benign Joint hypermobility syndrome. Younger female patients presenting with autonomic phenomena and early onset cervical injury should be examined for cervical myofascial pain syndrome and also for fibromyalgia syndrome since this study demonstrated a high percentage of fibromyalgia syndrome in these patients.

  11. Demographic estimation methods for plants with dormancy

    USGS Publications Warehouse

    Kery, M.; Gregg, K.B.

    2004-01-01

    Demographic studies in plants appear simple because unlike animals, plants do not run away. Plant individuals can be marked with, e.g., plastic tags, but often the coordinates of an individual may be sufficient to identify it. Vascular plants in temperate latitudes have a pronounced seasonal life-cycle, so most plant demographers survey their study plots once a year often during or shortly after flowering. Life-states are pervasive in plants, hence the results of a demographic study for an individual can be summarized in a familiar encounter history, such as OVFVVF000. A zero means that an individual was not seen in a year and a letter denotes its state for years when it was seen aboveground. V and F here stand for vegetative and flowering states, respectively. Probabilities of survival and state transitions can then be obtained by mere counting. Problems arise when there is an unobservable dormant state, I.e., when plants may stay belowground for one or more growing seasons. Encounter histories such as OVFOOF000 may then occur where the meaning of zeroes becomes ambiguous. A zero can either mean a dead or a dormant plant. Various ad hoc methods in wide use among plant ecologists have made strong assumptions about when a zero should be equated to a dormant individual. These methods have never been compared among each other. In our talk and in Kery et al. (submitted), we show that these ad hoc estimators provide spurious estimates of survival and should not be used. In contrast, if detection probabilities for aboveground plants are known or can be estimated, capture-recapture (CR) models can be used to estimate probabilities of survival and state-transitions and the fraction of the population that is dormant. We have used this approach in two studies of terrestrial orchids, Cleistes bifaria (Kery et aI., submitted) and Cypripedium reginae (Kery & Gregg, submitted) in West Virginia, U.S.A. For Cleistes, our data comprised one population with a total of 620 marked

  12. Comparative demographics of a Hawaiian forest bird community

    USGS Publications Warehouse

    Guillaumet, Alban; Woodworth, Bethany L.; Camp, Richard J.; Paxton, Eben

    2016-01-01

    Estimates of demographic parameters such as survival and reproductive success are critical for guiding management efforts focused on species of conservation concern. Unfortunately, reliable demographic parameters are difficult to obtain for any species, but especially for rare or endangered species. Here we derived estimates of adult survival and recruitment in a community of Hawaiian forest birds, including eight native species (of which three are endangered) and two introduced species at Hakalau Forest National Wildlife Refuge, Hawaiʻi. Integrated population models (IPM) were used to link mark–recapture data (1994–1999) with long-term population surveys (1987–2008). To our knowledge, this is the first time that IPM have been used to characterize demographic parameters of a whole avian community, and provides important insights into the life history strategies of the community. The demographic data were used to test two hypotheses: 1) arthropod specialists, such as the ‘Akiapōlā‘au Hemignathus munroi, are ‘slower’ species characterized by a greater relative contribution of adult survival to population growth, i.e. lower fecundity and increased adult survival; and 2) a species’ susceptibility to environmental change, as reflected by its conservation status, can be predicted by its life history traits. We found that all species were characterized by a similar population growth rate around one, independently of conservation status, origin (native vs non-native), feeding guild, or life history strategy (as measured by ‘slowness’), which suggested that the community had reached an equilibrium. However, such stable dynamics were achieved differently across feeding guilds, as demonstrated by a significant increase of adult survival and a significant decrease of recruitment along a gradient of increased insectivory, in support of hypothesis 1. Supporting our second hypothesis, we found that slower species were more vulnerable species at the global

  13. Alcohol Consumption in Demographic Subpopulations

    PubMed Central

    Delker, Erin; Brown, Qiana; Hasin, Deborah S.

    2016-01-01

    Alcohol consumption is common across subpopulations in the United States. However, the health burden associated with alcohol consumption varies across groups, including those defined by demographic characteristics such as age, race/ethnicity, and gender. Large national surveys, such as the National Epidemiologic Survey on Alcohol and Related Conditions and the National Survey on Drug Use and Health, found that young adults ages 18–25 were at particularly high risk of alcohol use disorder and unintentional injury caused by drinking. These surveys furthermore identified significant variability in alcohol consumption and its consequences among racial/ethnic groups. White respondents reported the highest prevalence of current alcohol consumption, whereas alcohol abuse and dependence were most prevalent among Native Americans. Native Americans and Blacks also were most vulnerable to alcohol-related health consequences. Even within ethnic groups, there was variability between and among different subpopulations. With respect to gender, men reported more alcohol consumption and binge drinking than women, especially in older cohorts. Men also were at greater risk of alcohol abuse and dependence, liver cirrhosis, homicide after alcohol consumption, and drinking and driving. Systematic identification and measurement of the variability across demographics will guide prevention and intervention efforts, as well as future research. PMID:27159807

  14. The prevalence of chondrocalcinosis (CC) of the acromioclavicular (AC) joint on chest radiographs and correlation with calcium pyrophosphate dihydrate (CPPD) crystal deposition disease

    PubMed Central

    Carrera, Guillermo; Baynes, Keith; Mautz, Alan; DuBois, Melissa; Cerniglia, Ross; Ryan, Lawrence M.

    2016-01-01

    Digital imaging combined with picture archiving and communication system (PACS) access allows detailed image retrieval and magnification. Calcium pyrophosphate dihydrate (CPPD) crystals preferentially deposit in fibrocartilages, the cartilage of the acromioclavicular (AC) joint being one such structure. We sought to determine if examination of the AC joints on magnified PACS imaging of chest films would be useful in identifying chondrocalcinosis (CC). Retrospective radiographic readings and chart reviews involving 1,920 patients aged 50 or more who had routine outpatient chest radiographs over a 4-month period were performed. Knee radiographs were available for comparison in 489 patients. Medical records were reviewed to abstract demographics, chest film reports, and diagnoses. AC joint CC was identified in 1.1 % (21/1,920) of consecutive chest films. Patients with AC joint CC were 75 years of age versus 65.4 in those without CC (p<0.0002). Four hundred eighty-nine patients had knee films. Six of these patients had AC joint CC, and of these, five also had knee CC (83 %). Of the 483 without AC joint CC, 62 (12 %) had knee CC (p=0.002). Patients with AC joint CC were more likely to have a recorded history of CPPD crystal deposition disease than those without AC joint CC (14 versus 1 %, p=0.0017). The prevalence of AC joint CC increases with age and is associated with knee CC. A finding of AC joint CC should heighten suspicion of pseudogout or secondary osteoarthritis in appropriate clinical settings and, in a young patient, should alert the clinician to the possibility of an associated metabolic condition. PMID:23609408

  15. The prevalence of chondrocalcinosis (CC) of the acromioclavicular (AC) joint on chest radiographs and correlation with calcium pyrophosphate dihydrate (CPPD) crystal deposition disease.

    PubMed

    Parperis, Konstantinos; Carrera, Guillermo; Baynes, Keith; Mautz, Alan; Dubois, Melissa; Cerniglia, Ross; Ryan, Lawrence M

    2013-09-01

    Digital imaging combined with picture archiving and communication system (PACS) access allows detailed image retrieval and magnification. Calcium pyrophosphate dihydrate (CPPD) crystals preferentially deposit in fibrocartilages, the cartilage of the acromioclavicular (AC) joint being one such structure. We sought to determine if examination of the AC joints on magnified PACS imaging of chest films would be useful in identifying chondrocalcinosis (CC). Retrospective radiographic readings and chart reviews involving 1,920 patients aged 50 or more who had routine outpatient chest radiographs over a 4-month period were performed. Knee radiographs were available for comparison in 489 patients. Medical records were reviewed to abstract demographics, chest film reports, and diagnoses. AC joint CC was identified in 1.1 % (21/1,920) of consecutive chest films. Patients with AC joint CC were 75 years of age versus 65.4 in those without CC (p < 0.0002). Four hundred eighty-nine patients had knee films. Six of these patients had AC joint CC, and of these, five also had knee CC (83 %). Of the 483 without AC joint CC, 62 (12 %) had knee CC (p = 0.002). Patients with AC joint CC were more likely to have a recorded history of CPPD crystal deposition disease than those without AC joint CC (14 versus 1 %, p = 0.0017). The prevalence of AC joint CC increases with age and is associated with knee CC. A finding of AC joint CC should heighten suspicion of pseudogout or secondary osteoarthritis in appropriate clinical settings and, in a young patient, should alert the clinician to the possibility of an associated metabolic condition.

  16. Joint assembly

    NASA Technical Reports Server (NTRS)

    Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

    2010-01-01

    A joint assembly is provided which includes a drive assembly and a swivel mechanism. The drive assembly features a motor operatively associated with a plurality of drive shafts for driving auxiliary elements, and a plurality of swivel shafts for pivoting the drive assembly. The swivel mechanism engages the swivel shafts and has a fixable element that may be attached to a foundation. The swivel mechanism is adapted to cooperate with the swivel shafts to pivot the drive assembly with at least two degrees of freedom relative to the foundation. The joint assembly allows for all components to remain encased in a tight, compact, and sealed package, making it ideal for space, exploratory, and commercial applications.

  17. Molecular evidence for a recent demographic expansion in the puma (Puma concolor) (Mammalia, Felidae).

    PubMed

    Matte, Eunice M; Castilho, Camila S; Miotto, Renata A; Sana, Denis A; Johnson, Warren E; O'Brien, Stephen J; de Freitas, Thales R O; Eizirik, Eduardo

    2013-12-01

    The puma is an iconic predator that ranges throughout the Americas, occupying diverse habitats. Previous phylogeographic analyses have revealed that it exhibits moderate levels of genetic structure across its range, with few of the classically recognized subspecies being supported as distinct demographic units. Moreover, most of the species' molecular diversity was found to be in South America. To further investigate the phylogeographic structure and demographic history of pumas we analyzed mtDNA sequences from 186 individuals sampled throughout their range, with emphasis on South America. Our objectives were to refine the phylogeographic assessment within South America and to investigate the demographic history of pumas using a coalescent approach. Our results extend previous phylogeographic findings, reassessing the delimitation of historical population units in South America and demonstrating that this species experienced a considerable demographic expansion in the Holocene, ca. 8,000 years ago. Our analyses indicate that this expansion occurred in South America, prior to the hypothesized re-colonization of North America, which was therefore inferred to be even more recent. The estimated demographic history supports the interpretation that pumas suffered a severe demographic decline in the Late Pleistocene throughout their distribution, followed by population expansion and re-colonization of the range, initiating from South America.

  18. Molecular evidence for a recent demographic expansion in the puma (Puma concolor) (Mammalia, Felidae)

    PubMed Central

    Matte, Eunice M.; Castilho, Camila S.; Miotto, Renata A.; Sana, Denis A.; Johnson, Warren E.; O’Brien, Stephen J.; de Freitas, Thales R. O.; Eizirik, Eduardo

    2013-01-01

    The puma is an iconic predator that ranges throughout the Americas, occupying diverse habitats. Previous phylogeographic analyses have revealed that it exhibits moderate levels of genetic structure across its range, with few of the classically recognized subspecies being supported as distinct demographic units. Moreover, most of the species’ molecular diversity was found to be in South America. To further investigate the phylogeographic structure and demographic history of pumas we analyzed mtDNA sequences from 186 individuals sampled throughout their range, with emphasis on South America. Our objectives were to refine the phylogeographic assessment within South America and to investigate the demographic history of pumas using a coalescent approach. Our results extend previous phylogeographic findings, reassessing the delimitation of historical population units in South America and demonstrating that this species experienced a considerable demographic expansion in the Holocene, ca. 8,000 years ago. Our analyses indicate that this expansion occurred in South America, prior to the hypothesized re-colonization of North America, which was therefore inferred to be even more recent. The estimated demographic history supports the interpretation that pumas suffered a severe demographic decline in the Late Pleistocene throughout their distribution, followed by population expansion and re-colonization of the range, initiating from South America. PMID:24385863

  19. Demographic Change and Parent-Child Relationships in Adulthood

    PubMed Central

    Seltzer, Judith A.; Bianchi, Suzanne M.

    2014-01-01

    Demographic changes in who becomes a parent, how many children parents have, and the marital statuses of parents and children affect the extent to which parents and adult children provide for each other later in life. We describe these demographic changes and their implications for the help parents and children give each other throughout their adult years. The changing demography of US families has increased both generations’ need for family assistance among those already disadvantaged and has exacerbated differences between the socioeconomically advantaged and disadvantaged in the availability of kin support. Variations in the marital histories of parents and children also contribute to a divergence between mother-child and father-child relationships in later life. The churning of couple relationships in both generations blurs the boundaries between who is in the family and who is not, threatening the effectiveness of the family safety net among those who may need it the most. PMID:25378767

  20. Intellectual History, Social History, Cultural History...and Our History.

    ERIC Educational Resources Information Center

    Nord, David Paul

    1990-01-01

    Defines and explores the links among intellectual, social, and cultural history. Warns that an adequate foundation must be laid in the economic and institutional social history of mass media before communication historians jump into cultural history. (SR)

  1. [Demographic development of the population].

    PubMed

    Diepgen, Thomas L

    2005-09-01

    During the last century the median life expectation age was lengthened about 30 years in Germany. According to recent prognoses this trend will continue over the next decades. Not only the number of people older than 60 years but also its percentage within the population was and will be increasing dramatically. This has important socio-economic, political and health-economic consequences. The increasing older population has an important impact on Dermatology. The incidence of many skin diseases is increasing with age due to life long exposure (e. g. UV-light), and aging processes are affecting the skin, its functions and immunology. Last not least, the distinction between skin disease and "cosmetic" skin problems has changed in the past decades in our society. Even a small reduction in the threshold of what the public and health professionals regard as a skin complaint worthy of medical attention could lead to a large increase in future dermatology service requirements. The demographic changes in our society are becoming an important issue in dermatological health care research. PMID:16117743

  2. Ancient DNA and human history.

    PubMed

    Slatkin, Montgomery; Racimo, Fernando

    2016-06-01

    We review studies of genomic data obtained by sequencing hominin fossils with particular emphasis on the unique information that ancient DNA (aDNA) can provide about the demographic history of humans and our closest relatives. We concentrate on nuclear genomic sequences that have been published in the past few years. In many cases, particularly in the Arctic, the Americas, and Europe, aDNA has revealed historical demographic patterns in a way that could not be resolved by analyzing present-day genomes alone. Ancient DNA from archaic hominins has revealed a rich history of admixture between early modern humans, Neanderthals, and Denisovans, and has allowed us to disentangle complex selective processes. Information from aDNA studies is nowhere near saturation, and we believe that future aDNA sequences will continue to change our understanding of hominin history.

  3. Ancient DNA and human history

    PubMed Central

    Slatkin, Montgomery; Racimo, Fernando

    2016-01-01

    We review studies of genomic data obtained by sequencing hominin fossils with particular emphasis on the unique information that ancient DNA (aDNA) can provide about the demographic history of humans and our closest relatives. We concentrate on nuclear genomic sequences that have been published in the past few years. In many cases, particularly in the Arctic, the Americas, and Europe, aDNA has revealed historical demographic patterns in a way that could not be resolved by analyzing present-day genomes alone. Ancient DNA from archaic hominins has revealed a rich history of admixture between early modern humans, Neanderthals, and Denisovans, and has allowed us to disentangle complex selective processes. Information from aDNA studies is nowhere near saturation, and we believe that future aDNA sequences will continue to change our understanding of hominin history. PMID:27274045

  4. Ancient DNA and human history.

    PubMed

    Slatkin, Montgomery; Racimo, Fernando

    2016-06-01

    We review studies of genomic data obtained by sequencing hominin fossils with particular emphasis on the unique information that ancient DNA (aDNA) can provide about the demographic history of humans and our closest relatives. We concentrate on nuclear genomic sequences that have been published in the past few years. In many cases, particularly in the Arctic, the Americas, and Europe, aDNA has revealed historical demographic patterns in a way that could not be resolved by analyzing present-day genomes alone. Ancient DNA from archaic hominins has revealed a rich history of admixture between early modern humans, Neanderthals, and Denisovans, and has allowed us to disentangle complex selective processes. Information from aDNA studies is nowhere near saturation, and we believe that future aDNA sequences will continue to change our understanding of hominin history. PMID:27274045

  5. Demographic manipulation in the Caucasus (with special reference to Georgia).

    PubMed

    Hewitt, B G

    1995-01-01

    The author discusses political developments in the Caucasus region since the collapse of the Soviet Union. The focus is on the events in Georgia that led to the war in South Ossetia (particularly in Abkhazia), and the author suggests that this development is the latest in a 200-year history of demographic manipulation of minority peoples by the region's two major powers, Russia and Georgia. Parallels are drawn between the Georgian war in Abkhazia and Russia's war in Chechenia. The author questions the value of the principle of territorial integrity, and suggests that alternative principles safeguarding the rights of ethnic minorities would be more appropriate in these circumstances.

  6. The Unaddressed Costs of Changing Student Demographics

    ERIC Educational Resources Information Center

    Kaplan, Leslie S.; Owings, William A.

    2013-01-01

    This article discusses the impact of changing student demographics on financing education and on our national wellbeing. We begin by examining the research of current student demographics and their relationship to learning and education costs. We then calculate a 1% cost factor from the average per-pupil expenditure based on the 2011 "Digest…

  7. The Epidemiology and Demographics of Hip Dysplasia

    PubMed Central

    Loder, Randall T.; Skopelja, Elaine N.

    2011-01-01

    The etiology of developmental dysplasia of the hip (DDH) is unknown. There are many insights, however, from epidemiologic/demographic information. A systematic medical literature review regarding DDH was performed. There is a predominance of left-sided (64.0%) and unilateral disease (63.4%). The incidence per 1000 live births ranges from 0.06 in Africans in Africa to 76.1 in Native Americans. There is significant variability in incidence within each racial group by geographic location. The incidence of clinical neonatal hip instability at birth ranges from 0.4 in Africans to 61.7 in Polish Caucasians. Predictors of DDH are breech presentation, positive family history, and gender (female). Children born premature, with low birth weights, or to multifetal pregnancies are somewhat protected from DDH. Certain HLA A, B, and D types demonstrate an increase in DDH. Chromosome 17q21 is strongly associated with DDH. Ligamentous laxity and abnormalities in collagen metabolism, estrogen metabolism, and pregnancy-associated pelvic instability are well-described associations with DDH. Many studies demonstrate an increase of DDH in the winter, both in the northern and southern hemispheres. Swaddling is strongly associated with DDH. Amniocentesis, premature labor, and massive radiation exposure may increase the risk of DDH. Associated conditions are congenital muscular torticollis and congenital foot deformities. The opposite hip is frequently abnormal when using rigorous radiographic assessments. The role of acetabular dysplasia and adult hip osteoarthritis is complex. Archeological studies demonstrate that the epidemiology of DDH may be changing. PMID:24977057

  8. India in the demographic trap.

    PubMed

    Reddy, P H

    1989-12-01

    Since 1980, India has experienced no further declines in the birth rate while mortality continues to drop. The birth rate has remained constant at 32-33/1000 despite dramatic increases in the proportion of couples protected from unwanted pregnancy from 24% in 1980-81 to 41% in 1986-87. Without a national family planning program, India's birth rate certainly would have increased substantially during this period. Among the social factors that appear to have undone the effects of rising contraceptive prevalence are increases in the proportion of women in the 15-29 year age group, improved maternal nutritional and health status so that fecundability is increasing, and the erosion of traditional customs such as prolonged breastfeeding and remarriage by widows. In terms of economic conditions, there have been no improvements in the 1980s in per capita income that would push India into the 3rd stage of the demographic transition. Of concern is the theory that, when societies become trapped too long in this 2nd stage, economic decline and ecological deterioration occur. At present, foodgrain production has been able to keep pace with population increases, but such production cannot increase indefinitely without soil erosion, deforestation, and other environmental degradations. Moreover, when no more grasslands and forests are available for conversion to cropland, the number of landless households will increase. In fact, the number of landless households has already grown from 15 million in 1961 to 26 million in 1981 and is projected to reach 44 million by the year 2000. Among the implications of landlessless are agrarian conflicts, rural political unrest, low life expectancy, malnutrition, and illiteracy. To avoid the consequences of stagnation in the rate of fertility decline, the Government of India is urged to adopt an aggressive population control effort.

  9. A Demographic Perspective on Family Change

    PubMed Central

    Bianchi, Suzanne M.

    2014-01-01

    Demographic analysis seeks to understand how individual microlevel decisions about child-bearing, marriage and partnering, geographic mobility, and behaviors that influence health and longevity aggregate to macrolevel population trends and differentials in fertility, mortality and migration. In this review, I first discuss theoretical perspectives—classic demographic transition theory, the perspective of the “second demographic transition,” the spread of developmental idealism—that inform demographers’ understanding of macrolevel population change. Then, I turn to a discussion of the role that demographically informed data collection has played in illuminating family change since the mid-20th century in the United States. Finally, I discuss ways in which demographic theory and data collection might inform future areas of family research, particularly in the area of intergenerational family relationships and new and emerging family forms. PMID:26078785

  10. The Joint Effects of Lifestyle Factors and Comorbidities on the Risk of Colorectal Cancer: A Large Chinese Retrospective Case-Control Study

    PubMed Central

    Hu, Hai; Zhou, Yangyang; Ren, Shujuan; Wu, Jiajin; Zhu, Meiying; Chen, Donghui; Yang, Haiyan; Wang, Liwei

    2015-01-01

    Background Colorectal cancer (CRC) is a major cause of cancer morbidity and mortality. In previous epidemiologic studies, the respective correlation between lifestyle factors and comorbidity and CRC has been extensively studied. However, little is known about their joint effects on CRC. Methods We conducted a retrospective case-control study of 1,144 diagnosed CRC patients and 60,549 community controls. A structured questionnaire was administered to the participants about their socio-demographic factors, anthropometric measures, comorbidity history and lifestyle factors. Logistic regression model was used to calculate the odds ratio (ORs) and 95% confidence intervals (95%CIs) for each factor. According to the results from logistic regression model, we further developed healthy lifestyle index (HLI) and comorbidity history index (CHI) to investigate their independent and joint effects on CRC risk. Results Four lifestyle factors (including physical activities, sleep, red meat and vegetable consumption) and four types of comorbidity (including diabetes, hyperlipidemia, history of inflammatory bowel disease and polyps) were found to be independently associated with the risk of CRC in multivariant logistic regression model. Intriguingly, their combined pattern- HLI and CHI demonstrated significant correlation with CRC risk independently (ORHLI: 3.91, 95%CI: 3.13–4.88; ORCHI: 2.49, 95%CI: 2.11–2.93) and jointly (OR: 10.33, 95%CI: 6.59–16.18). Conclusions There are synergistic effects of lifestyle factors and comorbidity on the risk of colorectal cancer in the Chinese population. PMID:26710070

  11. [Gout in the temporomandibular joint].

    PubMed

    Deferm, J T; Barkhuysen, R; de Rooy, J; Coppen, C; Merkx, M Aw

    2016-06-01

    A 76-year-old woman, with a medical history of diabetes mellitus and hypertension, presented herself to an oral and maxillofacial surgeon with a sudden pre-auricular swelling of the right temporomandibular joint. As a result of the atypical clinical appearance and signs of local destruction in the initial panoramic x-ray, a malign process was first eliminated from consideration. With the aid of extensive diagnostics and an open biopsy, the diagnosis of gout was established. PMID:27275659

  12. Darwinian and demographic forces affecting human protein coding genes

    PubMed Central

    Nielsen, Rasmus; Hubisz, Melissa J.; Hellmann, Ines; Torgerson, Dara; Andrés, Aida M.; Albrechtsen, Anders; Gutenkunst, Ryan; Adams, Mark D.; Cargill, Michele; Boyko, Adam; Indap, Amit; Bustamante, Carlos D.; Clark, Andrew G.

    2009-01-01

    Past demographic changes can produce distortions in patterns of genetic variation that can mimic the appearance of natural selection unless the demographic effects are explicitly removed. Here we fit a detailed model of human demography that incorporates divergence, migration, admixture, and changes in population size to directly sequenced data from 13,400 protein coding genes from 20 European-American and 19 African-American individuals. Based on this demographic model, we use several new and established statistical methods for identifying genes with extreme patterns of polymorphism likely to be caused by Darwinian selection, providing the first genome-wide analysis of allele frequency distributions in humans based on directly sequenced data. The tests are based on observations of excesses of high frequency–derived alleles, excesses of low frequency–derived alleles, and excesses of differences in allele frequencies between populations. We detect numerous new genes with strong evidence of selection, including a number of genes related to psychiatric and other diseases. We also show that microRNA controlled genes evolve under extremely high constraints and are more likely to undergo negative selection than other genes. Furthermore, we show that genes involved in muscle development have been subject to positive selection during recent human history. In accordance with previous studies, we find evidence for negative selection against mutations in genes associated with Mendelian disease and positive selection acting on genes associated with several complex diseases. PMID:19279335

  13. Investigation of the Demographic and Selective Forces Shaping the Nucleotide Diversity of Genes Involved in Nod Factor Signaling in Medicago truncatula

    PubMed Central

    De Mita, Stéphane; Ronfort, Joëlle; McKhann, Heather I.; Poncet, Charles; El Malki, Redouane; Bataillon, Thomas

    2007-01-01

    Symbiotic nitrogen-fixing rhizobia are able to trigger root deformation in their Fabaceae host plants, allowing their intracellular accommodation. They do so by delivering molecules called Nod factors. We analyzed the patterns of nucleotide polymorphism of five genes controlling early Nod factor perception and signaling in the Fabaceae Medicago truncatula to understand the selective forces shaping the evolution of these genes. We used 30 M. truncatula genotypes sampled in a genetically homogeneous region of the species distribution range. We first sequenced 24 independent loci and detected a genomewide departure from the hypothesis of neutrality and demographic equilibrium that suggests a population expansion. These data were used to estimate parameters of a simple demographic model incorporating population expansion. The selective neutrality of genes controlling Nod factor perception was then examined using a combination of two complementary neutrality tests, Tajima's D and Fay and Wu's standardized H. The joint distribution of D and H expected under neutrality was obtained under the fitted population expansion model. Only the gene DMI1, which is expected to regulate the downstream signal, shows a pattern consistent with a putative selective event. In contrast, the receptor-encoding genes NFP and NORK show no significant signatures of selection. Among the genes that we analyzed, only DMI1 should be viewed as a candidate for adaptation in the recent history of M. truncatula. PMID:18073426

  14. [Discussion on the lubrication mechanism of natural and artificial human joints].

    PubMed

    Wang, Y; Wang, C

    2001-12-01

    The lubrication mechanism of natural and artificial human joints was discussed in this paper. The history of joint lubrication research was reviewed briefly. Some key problems in joint lubrication were addressed. The clinical use of results obtained in studies of joint lubrication mechanism was also discussed in the paper.

  15. Joint x-ray

    MedlinePlus

    X-ray - joint; Arthrography; Arthrogram ... x-ray technologist will help you position the joint to be x-rayed on the table. Once in place, pictures are taken. The joint may be moved into other positions for more ...

  16. Joint Instability and Osteoarthritis

    PubMed Central

    Blalock, Darryl; Miller, Andrew; Tilley, Michael; Wang, Jinxi

    2015-01-01

    Joint instability creates a clinical and economic burden in the health care system. Injuries and disorders that directly damage the joint structure or lead to joint instability are highly associated with osteoarthritis (OA). Thus, understanding the physiology of joint stability and the mechanisms of joint instability-induced OA is of clinical significance. The first section of this review discusses the structure and function of major joint tissues, including periarticular muscles, which play a significant role in joint stability. Because the knee, ankle, and shoulder joints demonstrate a high incidence of ligament injury and joint instability, the second section summarizes the mechanisms of ligament injury-associated joint instability of these joints. The final section highlights the recent advances in the understanding of the mechanical and biological mechanisms of joint instability-induced OA. These advances may lead to new opportunities for clinical intervention in the prevention and early treatment of OA. PMID:25741184

  17. Germ banks affect the inference of past demographic events.

    PubMed

    Živković, Daniel; Tellier, Aurélien

    2012-11-01

    Continuous progress in empirical population genetics based on the whole-genome polymorphism data requires the theoretical analysis of refined models in order to interpret the evolutionary history of populations with adequate accuracy. Recent studies focus prevalently on the aspects of demography and adaptation, whereas age structure (for example, in plants via the maintenance of seed banks) has attracted less attention. Germ banking, that is, seed or egg dormancy, is a prevalent and important life-history trait in plants and invertebrates, which buffers against environmental variability and modulates species extinction in fragmented habitats. Within this study, we investigate the combined effect of germ banking and time-varying population size on the neutral coalescent and particularly derive the allele frequency spectrum under some simplifying assumptions. We then perform an ABC analysis using two simple demographic scenarios-a population expansion and an instantaneous decline. We demonstrate the appreciable influence of seed banks on the estimation of demographic parameters depending on the germination rate with biases scaled by the square of the germination rate. In the more complex case of a population bottleneck, which comprises an instantaneous decline and an expansion phase, ignoring information on the germination rate denies reliable estimates of the bottleneck parameters via the allelic spectrum. In particular, when seeds remain in the bank over several generations, recent expansions may remain invisible in the frequency spectrum, whereas ancient declines leave signatures much longer than in the absence of seed bank.

  18. Differentiate or Die: Colleges Need a Clear Niche to Thrive in the Coming Demographic Crisis

    ERIC Educational Resources Information Center

    Handy, Ty J.

    2008-01-01

    New England higher education is about to experience a decade-long demographic crisis unlike anything in its history. While the crisis will significantly affect all six New England States, it will be most acute in the three northern states, as the competition for qualified high school graduates begins to intensify. The New England states, including…

  19. Spacesuit mobility knee joints

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C. (Inventor)

    1979-01-01

    Pressure suit mobility joints are for use in interconnecting adjacent segments of an hermetically sealed spacesuit in which low torques, low leakage and a high degree of reliability are required. Each of the joints is a special purpose joint characterized by substantially constant volume and low torque characteristics and includes linkages which restrain the joint from longitudinal distension and includes a flexible, substantially impermeable diaphragm of tubular configuration spanning the distance between pivotally supported annuli. The diaphragms of selected joints include rolling convolutions for balancing the joints, while various joints include wedge-shaped sections which enhance the range of motion for the joints.

  20. Spacesuit mobility joints

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C. (Inventor)

    1978-01-01

    Joints for use in interconnecting adjacent segments of an hermetically sealed spacesuit which have low torques, low leakage and a high degree of reliability are described. Each of the joints is a special purpose joint characterized by substantially constant volume and low torque characteristics. Linkages which restrain the joint from longitudinal distension and a flexible, substantially impermeable diaphragm of tubular configuration spanning the distance between pivotally supported annuli are featured. The diaphragms of selected joints include rolling convolutions for balancing the joints, while various joints include wedge-shaped sections which enhance the range of motion for the joints.

  1. [Demographic transition or revolution? The weaknesses and implications of the demographic transition theory. Part 1: the origins].

    PubMed

    Bourcier De Carbon, P

    1998-01-01

    The work of Adolphe Landry is reviewed in relation to development of demographic transition theory. Landry was appointed administrator in 1912 of the National Alliance Against Depopulation and remained active in it his whole life. He also helped create family allowance programs in France. As early as 1909, Landry described three different population regimes. In the "primitive" regime, which characterized all nonhuman life and human life during most of history, the population was adjusted to available subsistence by mortality. In the "intermediate" phase, restrictions on marriage and control of reproduction outside marriage maintained the population at a level below the maximum supportable. In the "contemporary" regime, the universal practice of contraception and abortion could lead to very low levels of fertility. The spread of contraception and low fertility appeared to Landry a true demographic revolution. He attributed the acceptance of contraception to a change in the common aspirations of human beings regarding their conditions, a desire for improved material well-being and social advancement, and an increased spirit of rationality and even calculation in their behavior. Landry believed that the contemporary regime, unlike the preceding two, had no mechanism implying equilibrium. The demographic revolution freed fertility from social determinants and linked it more closely to individual interests. Landry expected the contemporary regime to spread throughout the entire world, with many areas still in the primitive phase passing directly to the contemporary. He was concerned with the effects of demographic aging, and he deplored birth control propaganda that claimed it as a cure for unemployment and for overpopulation in the poor Asian countries. The birth control movements in England and the US were successful in bringing the two countries into the contemporary regime. A number of organizations such as the Population Association of America and the Office of

  2. Demographic cycles, cohort size, and earnings.

    PubMed

    Berger, M C

    1989-05-01

    This article examines whether position in the demographic cycle is an important factor in determining earnings and earnings growth. Earnings equations for white males are estimated by using March Current Population Survey data. Position in the demographic cycle is captured by including both measures of own cohort size and the size of surrounding cohorts in the estimated earnings equations. Position in the demographic cycle matters. Increases in own cohort size lead to flatter earnings profiles, whereas increases in the size of surrounding cohorts are associated with steeper earnings profiles. The net effect is that those who enter the labor market before or after the peak of the demographic cycle start out with lower earnings but experience faster earnings growth. This pattern is uniform across all schooling groups: high school dropouts, high school graduates, those with some college, and college graduates.

  3. [Demographic processes and world population numbers].

    PubMed

    Donkov, K

    1986-01-01

    Recent global population trends are reviewed. The author notes the growing divergence in demographic trends between the developed and developing regions. These differences are analyzed in the light of Marxist population theory. (SUMMARY IN ENG AND RUS) PMID:12280530

  4. Temporomandibular joint involvement in ankylosing spondylitis

    PubMed Central

    Arora, Pallak; Amarnath, Janardhan; Ravindra, Setru Veerabhadrappa; Rallan, Mandeep

    2013-01-01

    Frequency of temporomandibular joint (TMJ) involvement in patients with ankylosing spondylitis (AS) has varied from 4% to 35%. It is more common in men and produces generalised stiffness in involved joints. Clinician should be suspicious of AS when a patient reports with painful restricted movements of joint, neck or back and with no trauma history. Conventional radiographic methods have allowed the demonstration of TMJ abnormalities in patients with AS, but CT is necessary to establish joint space relations and bony morphology. We describe a case of severe AS with TMJ involvement in a 40-year-old female patient and demonstrated TMJ changes on CT. A CT was able to demonstrate articular cartilage changes, disc- and joint abnormalities. Thus, if conventional radiographs in a symptomatic patient with rheumatic diseases are unable to demonstrate changes, CT can provide valuable additional information of the changes in the TMJ. PMID:23645650

  5. Custody after divorce: demographic and attitudinal patterns.

    PubMed

    Pearson, J; Thoennes, N

    1990-04-01

    In a reanalysis of data from a large sample of divorced parents, joint residential custody--and joint legal custody to a lesser extent--was shown to be a favorable arrangement for couples who chose it and for their children. Parents with joint custody reported better cooperation with former spouses and greater financial resources than did those with sole custody. No association was found between children's adjustment and form of custody.

  6. Demographic and Related Determinants of Recent Cuban Emigration.

    ERIC Educational Resources Information Center

    Briquets, Sergio Diaz

    1983-01-01

    Examines principal demographic determinants of recent Cuban emigration and discusses how these demographic variables interact with other social, economic, and political determinants. Suggests that Cuban labor migration is more responsive to demographic factors than some theorists assume. (Author/MJL)

  7. Trauma history is associated with prior suicide attempt history in hospitalized patients with major depressive disorder.

    PubMed

    Brown, Lily A; Armey, Michael A; Sejourne, Corinne; Miller, Ivan W; Weinstock, Lauren M

    2016-09-30

    Although the relationships between PTSD, abuse history, and suicidal behaviors are well-established in military and outpatient samples, little data is available on this relationship in inpatient samples. This study examines the relationships between these variables and related demographic and clinical correlates in a sample of psychiatric inpatients with a diagnosis of major depressive disorder using electronic medical record (EMR) data. Controlling for relevant demographic and clinical variables, PTSD diagnosis and history of abuse were both significantly associated with history of suicide attempt, but in a combined model, only history of abuse remained as a significant predictor. Whereas history of abuse was associated with a history multiple suicide attempts, PTSD diagnosis was not. Both insurance status and gender acted as significant moderators of the relationship between history of abuse and history of suicide attempt, with males and those with public/no insurance having greater associations with history of suicide attempts when an abuse history was present. These data indicate the importance of documentation of PTSD, abuse history, and history of suicide attempts. The results also suggest that in the presence of an abuse history or PTSD diagnosis, additional time spent on safety and aftercare planning following hospital discharge may be indicated.

  8. Trauma history is associated with prior suicide attempt history in hospitalized patients with major depressive disorder.

    PubMed

    Brown, Lily A; Armey, Michael A; Sejourne, Corinne; Miller, Ivan W; Weinstock, Lauren M

    2016-09-30

    Although the relationships between PTSD, abuse history, and suicidal behaviors are well-established in military and outpatient samples, little data is available on this relationship in inpatient samples. This study examines the relationships between these variables and related demographic and clinical correlates in a sample of psychiatric inpatients with a diagnosis of major depressive disorder using electronic medical record (EMR) data. Controlling for relevant demographic and clinical variables, PTSD diagnosis and history of abuse were both significantly associated with history of suicide attempt, but in a combined model, only history of abuse remained as a significant predictor. Whereas history of abuse was associated with a history multiple suicide attempts, PTSD diagnosis was not. Both insurance status and gender acted as significant moderators of the relationship between history of abuse and history of suicide attempt, with males and those with public/no insurance having greater associations with history of suicide attempts when an abuse history was present. These data indicate the importance of documentation of PTSD, abuse history, and history of suicide attempts. The results also suggest that in the presence of an abuse history or PTSD diagnosis, additional time spent on safety and aftercare planning following hospital discharge may be indicated. PMID:27416539

  9. Revolution without ideology: demographic transition in East Asia.

    PubMed

    Anderson, T D

    1980-01-01

    The acceleration of demographic transition in East Asia is a process of great potential import for the world. The most rapid and large scale transformation of demographic pattern in world history is being accomplished in this region. Demographic processes in other countries and regions have been viewed in the light of past events. Demographic transition has been accepted as a desirable goal, but its realization was believed subject to certain constraints. These include the need to attain high rates of economic growth in order to stimulate the transition and the longer period of time required to accomplish the transition. It was assumed that at least 2 generations would be subject to gradually diminishing rates of increase and slow cultural modification before transition entered its last phase. This interpretation of the preconditions and specific character of demographic transition has been subject to increasing challenge, and recent events in East Asia accentuate such doubts. Most new views begin with the premises that contemporary pretransition societies are not European in culture and the 1970s are not the 1880s. East Asia also differs culturally from other developing areas, including South and Southeast Asia. The most significant regional features are cultural. Demographic transition in the region began after World War 2 and somewhat differently in each East Asian country. The process began first in Japan. The 3rd phase was accomplished rapidly but not as a specific consequence of the modernization process. The end of World War 2 and the spurt in births accompanying military demobilization contributed to a population surge. The cultural factors of practicality, homogeneity, social discipline, and nearly universial literacy were decisive here. Abortion was legalized in 1948 and other forms of birth control were made readily available. Between 1947 and 1957 the birthrate was halved to 17/1000. In Taiwan and South Korea public concern about high rates of

  10. The Joint Allele-Frequency Spectrum in Closely Related Species

    PubMed Central

    Chen, Hua; Green, Richard E.; Pääbo, Svante; Slatkin, Montgomery

    2007-01-01

    We develop the theory for computing the joint frequency spectra of alleles in two closely related species. We allow for arbitrary population growth in both species after they had a common ancestor. We focus on the case in which a single chromosome is sequenced from one of the species. We use classical diffusion theory to show that, if the ancestral species was at equilibrium under mutation and drift and a chromosome from one of the descendant species carries the derived allele, the frequency spectrum in the other species is uniform, independently of the demographic history of both species. We also predict the expected densities of segregating and fixed sites when the chromosome from the other species carries the ancestral allele. We compare the predictions of our model with the site-frequency spectra of SNPs in the four HapMap populations of humans when the nucleotide present in the Neanderthal DNA sequence is ancestral or derived, using the chimp genome as the outgroup. PMID:17603120

  11. Identifying image preferences based on demographic attributes

    NASA Astrophysics Data System (ADS)

    Fedorovskaya, Elena A.; Lawrence, Daniel R.

    2014-02-01

    The intent of this study is to determine what sorts of images are considered more interesting by which demographic groups. Specifically, we attempt to identify images whose interestingness ratings are influenced by the demographic attribute of the viewer's gender. To that end, we use the data from an experiment where 18 participants (9 women and 9 men) rated several hundred images based on "visual interest" or preferences in viewing images. The images were selected to represent the consumer "photo-space" - typical categories of subject matter found in consumer photo collections. They were annotated using perceptual and semantic descriptors. In analyzing the image interestingness ratings, we apply a multivariate procedure known as forced classification, a feature of dual scaling, a discrete analogue of principal components analysis (similar to correspondence analysis). This particular analysis of ratings (i.e., ordered-choice or Likert) data enables the investigator to emphasize the effect of a specific item or collection of items. We focus on the influence of the demographic item of gender on the analysis, so that the solutions are essentially confined to subspaces spanned by the emphasized item. Using this technique, we can know definitively which images' ratings have been influenced by the demographic item of choice. Subsequently, images can be evaluated and linked, on one hand, to their perceptual and semantic descriptors, and, on the other hand, to the preferences associated with viewers' demographic attributes.

  12. Estimating demographic parameters using a combination of known-fate and open N-mixture models.

    PubMed

    Schmidt, Joshua H; Johnson, Devin S; Lindberg, Mark S; Adams, Layne G

    2015-10-01

    Accurate estimates of demographic parameters are required to infer appropriate ecological relationships and inform management actions. Known-fate data from marked individuals are commonly used to estimate survival rates, whereas N-mixture models use count data from unmarked individuals to estimate multiple demographic parameters. However, a joint approach combining the strengths of both analytical tools has not been developed. Here we develop an integrated model combining known-fate and open N-mixture models, allowing the estimation of detection probability, recruitment, and the joint estimation of survival. We demonstrate our approach through both simulations and an applied example using four years of known-fate and pack count data for wolves (Canis lupus). Simulation results indicated that the integrated model reliably recovered parameters with no evidence of bias, and survival estimates were more precise under the joint model. Results from the applied example indicated that the marked sample of wolves was biased toward individuals with higher apparent survival rates than the unmarked pack mates, suggesting that joint estimates may be more representative of the overall population. Our integrated model is a practical approach for reducing bias while increasing precision and the amount of information gained from mark-resight data sets. We provide implementations in both the BUGS language and an R package. PMID:26649379

  13. Estimating demographic parameters using a combination of known-fate and open N-mixture models

    USGS Publications Warehouse

    Schmidt, Joshua H.; Johnson, Devin S.; Lindberg, Mark S.; Adams, Layne G.

    2015-01-01

    Accurate estimates of demographic parameters are required to infer appropriate ecological relationships and inform management actions. Known-fate data from marked individuals are commonly used to estimate survival rates, whereas N-mixture models use count data from unmarked individuals to estimate multiple demographic parameters. However, a joint approach combining the strengths of both analytical tools has not been developed. Here we develop an integrated model combining known-fate and open N-mixture models, allowing the estimation of detection probability, recruitment, and the joint estimation of survival. We demonstrate our approach through both simulations and an applied example using four years of known-fate and pack count data for wolves (Canis lupus). Simulation results indicated that the integrated model reliably recovered parameters with no evidence of bias, and survival estimates were more precise under the joint model. Results from the applied example indicated that the marked sample of wolves was biased toward individuals with higher apparent survival rates than the unmarked pack mates, suggesting that joint estimates may be more representative of the overall population. Our integrated model is a practical approach for reducing bias while increasing precision and the amount of information gained from mark–resight data sets. We provide implementations in both the BUGS language and an R package.

  14. The demographic determinants of human microbiome health

    PubMed Central

    Estrela, Sylvie; Whiteley, Marvin; Brown, Sam P.

    2014-01-01

    The human microbiome is a vast reservoir of microbial diversity and increasingly recognized to play a fundamental role in human health. In polymicrobial communities, the presence of one species can modulate the demography (growth and distribution) of other species. These demographic impacts generate feedbacks in multi-species interactions, which can be magnified in spatially structured populations (e.g., host-associated communities). Here we argue that demographic feedbacks between species are central to microbiome development, shaping whether and how potential metabolic interactions come to be realized between expanding lineages of bacteria. Understanding how demographic feedbacks tune metabolic interactions and in turn shape microbiome structure and function is now a key challenge to our abilities to better manage microbiome health. PMID:25500524

  15. The demographic determinants of human microbiome health.

    PubMed

    Estrela, Sylvie; Whiteley, Marvin; Brown, Sam P

    2015-03-01

    The human microbiome is a vast reservoir of microbial diversity and increasingly recognized to have a fundamental role in human health. In polymicrobial communities, the presence of one species can modulate the demography (i.e., growth and distribution) of other species. These demographic impacts generate feedbacks in multispecies interactions, which can be magnified in spatially structured populations (e.g., host-associated communities). Here, we argue that demographic feedbacks between species are central to microbiome development, shaping whether and how potential metabolic interactions come to be realized between expanding lineages of bacteria. Understanding how demographic feedbacks tune metabolic interactions and in turn shape microbiome structure and function is now a key challenge to our abilities to better manage microbiome health.

  16. Robust demographic inference from genomic and SNP data.

    PubMed

    Excoffier, Laurent; Dupanloup, Isabelle; Huerta-Sánchez, Emilia; Sousa, Vitor C; Foll, Matthieu

    2013-10-01

    We introduce a flexible and robust simulation-based framework to infer demographic parameters from the site frequency spectrum (SFS) computed on large genomic datasets. We show that our composite-likelihood approach allows one to study evolutionary models of arbitrary complexity, which cannot be tackled by other current likelihood-based methods. For simple scenarios, our approach compares favorably in terms of accuracy and speed with ∂a∂i, the current reference in the field, while showing better convergence properties for complex models. We first apply our methodology to non-coding genomic SNP data from four human populations. To infer their demographic history, we compare neutral evolutionary models of increasing complexity, including unsampled populations. We further show the versatility of our framework by extending it to the inference of demographic parameters from SNP chips with known ascertainment, such as that recently released by Affymetrix to study human origins. Whereas previous ways of handling ascertained SNPs were either restricted to a single population or only allowed the inference of divergence time between a pair of populations, our framework can correctly infer parameters of more complex models including the divergence of several populations, bottlenecks and migration. We apply this approach to the reconstruction of African demography using two distinct ascertained human SNP panels studied under two evolutionary models. The two SNP panels lead to globally very similar estimates and confidence intervals, and suggest an ancient divergence (>110 Ky) between Yoruba and San populations. Our methodology appears well suited to the study of complex scenarios from large genomic data sets.

  17. Robust Demographic Inference from Genomic and SNP Data

    PubMed Central

    Excoffier, Laurent; Dupanloup, Isabelle; Huerta-Sánchez, Emilia; Sousa, Vitor C.; Foll, Matthieu

    2013-01-01

    We introduce a flexible and robust simulation-based framework to infer demographic parameters from the site frequency spectrum (SFS) computed on large genomic datasets. We show that our composite-likelihood approach allows one to study evolutionary models of arbitrary complexity, which cannot be tackled by other current likelihood-based methods. For simple scenarios, our approach compares favorably in terms of accuracy and speed with , the current reference in the field, while showing better convergence properties for complex models. We first apply our methodology to non-coding genomic SNP data from four human populations. To infer their demographic history, we compare neutral evolutionary models of increasing complexity, including unsampled populations. We further show the versatility of our framework by extending it to the inference of demographic parameters from SNP chips with known ascertainment, such as that recently released by Affymetrix to study human origins. Whereas previous ways of handling ascertained SNPs were either restricted to a single population or only allowed the inference of divergence time between a pair of populations, our framework can correctly infer parameters of more complex models including the divergence of several populations, bottlenecks and migration. We apply this approach to the reconstruction of African demography using two distinct ascertained human SNP panels studied under two evolutionary models. The two SNP panels lead to globally very similar estimates and confidence intervals, and suggest an ancient divergence (>110 Ky) between Yoruba and San populations. Our methodology appears well suited to the study of complex scenarios from large genomic data sets. PMID:24204310

  18. History of the Space Radiation Effects (SPACERAD) Program for the joint USAF/NASA CRRES mission. Part 1. From the origins through the launch, 1981-1990. Interim report

    SciTech Connect

    Liebowitz, R.P.

    1992-03-16

    The history narrates the Space Radiation Effects (SPACERAD) Program from its origins in 1981 through the launch of the SPACERAD experiments on the USAF/NASA Combined Release/Radiation Effects Satellite (CRRES) on July 25, 1990 and the initial data results in October 1990. The SPACERAD Program comprised a coordinated schedule of space-and-ground testing of state-of-the-art microelectronics, together with new satellite measurements of the Earth's radiation belts. The goals for the program were to produce improved standards and procedures for ground-testing future space microelectronics and new dynamic models of the radiation belts. The history discusses programmatic, management and funding issues that arose in the course of its realization.

  19. Butt Joint Tool Commissioning

    SciTech Connect

    Martovetsky, N N

    2007-12-06

    ITER Central Solenoid uses butt joints for connecting the pancakes in the CS module. The principles of the butt joining of the CICC were developed by the JAPT during CSMC project. The difference between the CSMC butt joint and the CS butt joint is that the CS butt joint is an in-line joint, while the CSMC is a double joint through a hairpin jumper. The CS butt joint has to carry the hoop load. The straight length of the joint is only 320 mm, and the vacuum chamber around the joint has to have a split in the clamp shell. These requirements are challenging. Fig.1 presents a CSMC joint, and Fig.2 shows a CS butt joint. The butt joint procedure was verified and demonstrated. The tool is capable of achieving all specified parameters. The vacuum in the end was a little higher than the target, which is not critical and readily correctable. We consider, tentatively that the procedure is established. Unexpectedly, we discover significant temperature nonuniformity in the joint cross section, which is not formally a violation of the specs, but is a point of concern. All testing parameters are recorded for QA purposes. We plan to modify the butt joining tool to improve its convenience of operation and provide all features necessary for production of butt joints by qualified personnel.

  20. Population momentum across vertebrate life histories

    USGS Publications Warehouse

    Koons, D.N.; Grand, J.B.; Arnold, J.M.

    2006-01-01

    Population abundance is critically important in conservation, management, and demographic theory. Thus, to better understand how perturbations to the life history affect long-term population size, we examined population momentum for four vertebrate classes with different life history strategies. In a series of demographic experiments we show that population momentum generally has a larger effect on long-term population size for organisms with long generation times than for organisms with short generation times. However, patterns between population momentum and generation time varied across taxonomic groups and according to the life history parameter that was changed. Our findings indicate that momentum may be an especially important aspect of population dynamics for long-lived vertebrates, and deserves greater attention in life history studies. Further, we discuss the importance of population momentum in natural resource management, pest control, and conservation arenas. ?? 2006 Elsevier B.V. All rights reserved.

  1. Rural vs. urban utilization of total joint arthroplasty.

    PubMed

    Banerjee, Devraj; Illingworth, Kenneth David; Novicoff, Wendy M; Scaife, Steven L; Jones, Braden K; Saleh, Khaled J

    2013-06-01

    The purpose of this study was to analyze the association between patient demographics and hospital demographics on utilization of total joint arthroplasty in rural and urban populations from the National Inpatient Sample database. Any patient that was discharged after a primary total hip or primary total knee arthroplasty was included in this study. Results showed that rural patients living in a Northeastern hospital region compared to West, less than 65 years of age, females, Blacks and Hispanics were less likely to undergo total joint arthroplasty compared to their urban counterparts. Rural patient were more likely to undergo total joint arthroplasty compared to their urban counterparts if they were in the Midwest and had Medicare as their primary payer provider.

  2. Demographics, political power and economic growth.

    PubMed

    Holtz-eakin, D

    1993-01-01

    "Growth theory may be used to predict the response of saving, capital formation, and output growth to large demographic shifts. Such large shifts would also be expected to alter the demand for government services and the desired levels of taxation in the population. This paper extends the overlapping-generations model of economic growth to predict the evolution of government tax and spending policy through the course of a major demographic shift. Simulations suggest that this approach may yield valuable insights into the evolution of policy in the United States and other industrialized economies." PMID:12233623

  3. [Demographic and economic development in contemporary Mexico].

    PubMed

    Alba, F

    1989-01-01

    This paper briefly reviews the main features of the recent Mexican experience in demographic and economic development matters. It assesses the development pattern that prevailed between 1940 and 1970 and the ways and policies that were instrumental in accommodating the rapid population growth of the period. The author considers that by 1970 the relatively acceptable demo-economic system in place since 1940 entered a period of emerging tensions, and examines the responses to those difficulties, among them the change in population policy. It closes with a brief review of the tasks ahead considering future demographic and economic tendencies in Mexico. PMID:2740942

  4. Estimating demographic parameters using hidden process dynamic models.

    PubMed

    Gimenez, Olivier; Lebreton, Jean-Dominique; Gaillard, Jean-Michel; Choquet, Rémi; Pradel, Roger

    2012-12-01

    Structured population models are widely used in plant and animal demographic studies to assess population dynamics. In matrix population models, populations are described with discrete classes of individuals (age, life history stage or size). To calibrate these models, longitudinal data are collected at the individual level to estimate demographic parameters. However, several sources of uncertainty can complicate parameter estimation, such as imperfect detection of individuals inherent to monitoring in the wild and uncertainty in assigning a state to an individual. Here, we show how recent statistical models can help overcome these issues. We focus on hidden process models that run two time series in parallel, one capturing the dynamics of the true states and the other consisting of observations arising from these underlying possibly unknown states. In a first case study, we illustrate hidden Markov models with an example of how to accommodate state uncertainty using Frequentist theory and maximum likelihood estimation. In a second case study, we illustrate state-space models with an example of how to estimate lifetime reproductive success despite imperfect detection, using a Bayesian framework and Markov Chain Monte Carlo simulation. Hidden process models are a promising tool as they allow population biologists to cope with process variation while simultaneously accounting for observation error. PMID:22373775

  5. Demographic analysis from summaries of an age-structured population

    USGS Publications Warehouse

    Link, W.A.; Royle, J. Andrew; Hatfield, J.S.

    2003-01-01

    Demographic analyses of age-structured populations typically rely on life history data for individuals, or when individual animals are not identified, on information about the numbers of individuals in each age class through time. While it is usually difficult to determine the age class of a randomly encountered individual, it is often the case that the individual can be readily and reliably assigned to one of a set of age classes. For example, it is often possible to distinguish first-year from older birds. In such cases, the population age structure can be regarded as a latent variable governed by a process prior, and the data as summaries of this latent structure. In this article, we consider the problem of uncovering the latent structure and estimating process parameters from summaries of age class information. We present a demographic analysis for the critically endangered migratory population of whooping cranes (Grus americana), based only on counts of first-year birds and of older birds. We estimate age and year-specific survival rates. We address the controversial issue of whether management action on the breeding grounds has influenced recruitment, relating recruitment rates to the number of seventh-year and older birds, and examining the pattern of variation through time in this rate.

  6. Pressure suit joint analyzer

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C.; Webbon, B. W. (Inventor)

    1982-01-01

    A measurement system for simultaneously measuring torque and angular flexure in a pressure suit joint is described. One end of a joint under test is held rigid. A torque transducer is pivotably supported on the other movable end of a joint. A potentiometer is attached to the transducer by an arm. The wiper shaft of the potentiometer is gripped by a reference arm that rotates the wiper shaft the same angle as the flexure of joint. A signal is generated by the potentiometer which is representative of the joint flexure. A compensation circuit converts the output of the transducer to a signal representative of joint torque.

  7. Canadian History.

    ERIC Educational Resources Information Center

    School Libraries in Canada, 2003

    2003-01-01

    Includes 22 articles that address Canadian history and the importance of having students honor Canada's past by providing articles relating to the areas of History and Social Studies covering: historical fiction as instructional material; Canadian scientists; agricultural fairs; the Historical Foundation; social science books on Canada; student…

  8. Child maltreatment syndrome: demographics and developmental issues of inpatient cases

    PubMed Central

    Ngiam, Xin Ying; Kang, Ying Qi; Aishworiya, Ramkumar; Kiing, Jennifer; Law, Evelyn Chung Ning

    2015-01-01

    INTRODUCTION This study aimed to describe the demographic, social, developmental and behavioural profile of children hospitalised for alleged child maltreatment syndrome (CMS). METHODS This study was a retrospective review of the consecutive inpatient records of children (0–16 years) admitted to the National University Hospital, Singapore, for alleged CMS over a three-year period. Descriptive data on the demographic characteristics, alleged maltreatment, medical and developmental histories, and family background of these children were collected and analysed. Chi-square statistics were used to test whether family factors were associated with the type of maltreatment and the presence of developmental disorders. RESULTS A total of 89 children, who accounted for 90 admission cases, were studied. Physical abuse (70.0%) was the most common, followed by neglect (11.1%) and sexual abuse (7.8%). Child protection services had already been involved in 29.2% of the cases prior to the child’s admission. Children who were victims of abuse were more likely to come from homes with a prior history of domestic violence (p = 0.028). Financial difficulty was found to be a risk factor for neglect (p = 0.005). Among the 89 children, 15.7% were found to have developmental disorders and 10.1% had mental health diagnoses. Children who had developmental disorders were more likely to have a parent with a mental health disorder (p = 0.002). CONCLUSION A sizeable proportion of the children admitted for alleged CMS had developmental or behavioural disorders. Clinicians have a role in ensuring that these children have appropriate follow-up plans. Children from high-risk families should be screened for maltreatment. PMID:26668405

  9. The Demographics of Corporal Punishment in Texas

    ERIC Educational Resources Information Center

    Phillips, Stephanie

    2012-01-01

    This dissertation examined the student discipline policies of 1,025 Texas school districts, as well as data from the Texas Education Agency's Academic Excellence Indicator System in order to identify demographic patterns regarding corporal punishment policies in Texas schools. The study also studied the relationship between a district's…

  10. A Model for External Demographic Analysis.

    ERIC Educational Resources Information Center

    Hall, Barbara Ann

    A data-collection model is presented for the gathering of timely information on population demographic characteristics, as well as economic, educational, environmental, and social trends. First, the paper discusses the importance of anticipating internal and external changes and establishing priorities for resource allocation in the design of a…

  11. Demographic development in ASEAN: a comparative overview.

    PubMed

    Herrin, A N; Pardoko, H; Lim, L L; Hongladorom, C

    1981-01-01

    A comparative overview of recent demographic developments in the ASEAN (Association of Southeast Asian Nations) region is presented. Countries discussed include Indonesia, Malaysia, the Philippines, Singapore, and Thailand. Separate consideration is given to mortality; fertility; and migration, spatial distribution, and employment. A final section is concerned with emerging issues and directions for population policy. PMID:12178278

  12. Demographic Group Differences in Adolescents' Time Attitudes

    ERIC Educational Resources Information Center

    Andretta, James R.; Worrell, Frank C.; Mello, Zena R.; Dixson, Dante D.; Baik, Sharon H.

    2013-01-01

    In the present study, we examined demographic differences in time attitudes in a sample of 293 adolescents. Time attitudes were measured using the Adolescent Time Attitude Scale (Mello & Worrell, 2007; Worrell, Mello, & Buhl, 2011), which assesses positive and negative attitudes toward the past, the present, and the future. Generally, African…

  13. A Demographic Profile of Cuban Americans.

    ERIC Educational Resources Information Center

    Boswell, Thomas D.

    This study offers a demographic profile of the U.S. Cuban population, using data from the decennial census and current population surveys. Part one estimates the number of Cuban Americans and describes their geographic distribution nationwide. Part two compares the socioeconomic characteristics (age, gender, educational attainment, income,…

  14. Demographic and Lifestyle Variables Associated with Obesity

    ERIC Educational Resources Information Center

    Worthy, Sheri L.; Lokken, Kristine; Pilcher, Kenneth; Boeka, Abbe

    2010-01-01

    Objective: Overweight and obesity rates are associated with chronic diseases and higher rates of disability and continue to rise in the United States and worldwide. The purpose of this study was to build on past research and further investigate demographic and lifestyle variables associated with increased body mass index (BMI: kg/m[squared]).…

  15. Life Potential as a Basic Demographic Indicator

    ERIC Educational Resources Information Center

    Goerlich, Francisco J.; Soler, Angel

    2013-01-01

    This paper proposes an indicator that integrates life expectancy with the demographic structure of the population for a given society. By doing this, we have a simple indicator of mortality and aging combined, which could be very useful for developed societies. As is widely known, life expectancy at birth is independent of the demographic…

  16. State Differences: The Key to Demographics.

    ERIC Educational Resources Information Center

    Hodgkinson, Harold

    1999-01-01

    This companion piece to a 1997 article examines United States demographic trends, such as diversity by age, "race" and U.S. Census racial classifications, wealth, transiency, suburbanization and sprawl, and immigration, focusing on differences among states and metro regions. Nothing, including achievement scores, social services, and financial…

  17. Demographic Projections and Educational Policy Issues.

    ERIC Educational Resources Information Center

    Little, Dennis L.

    Significant changes in various demographic patterns include a declining birth rate, regional shifts from the "Snow Belt" to the "Sun Belt" as well as a return to rural America, an increase in female labor force participation, a general change in family structure ("kids with kids," single parent families, unmarried couples, etc.), and changes in…

  18. Economic and Demographic Predictors of Inclusive Education

    ERIC Educational Resources Information Center

    Cosier, Meghan E.; Causton-Theoharis, Julie

    2011-01-01

    This study investigated economic and demographic predictors of levels of inclusion of students with disabilities in 129 school districts. Multiple regression analysis was utilized to address the following research questions: (a) Is there a relationship between economic factors and percentage of highly included students with disabilities in general…

  19. Demographic Trends Affecting the Future Labor Force.

    ERIC Educational Resources Information Center

    Taeuber, Karl E.

    This report reviews recent population and manpower projections and examines how they take into account certain unexpected shifts in demographic, social, and economic behavior. It also assesses how well the particular circumstances, trends, and problems of the nation's major minority groups have been brought into the purview of the projection…

  20. Demographic Change and Local School District Organization.

    ERIC Educational Resources Information Center

    Hanson, Ellis G.

    This paper summarizes a Great Plains School District Organization Project publication, People, Places, Perspectives: the Great Plains States, which was concerned with the demographic characteristics of the Midwest and their implications for educational planners. The author suggests that the challenges facing educational planners in the Midwest, as…

  1. Human population growth and the demographic transition

    PubMed Central

    Bongaarts, John

    2009-01-01

    The world and most regions and countries are experiencing unprecedentedly rapid demographic change. The most obvious example of this change is the huge expansion of human numbers: four billion have been added since 1950. Projections for the next half century expect a highly divergent world, with stagnation or potential decline in parts of the developed world and continued rapid growth in the least developed regions. Other demographic processes are also undergoing extraordinary change: women's fertility has dropped rapidly and life expectancy has risen to new highs. Past trends in fertility and mortality have led to very young populations in high fertility countries in the developing world and to increasingly older populations in the developed world. Contemporary societies are now at very different stages of their demographic transitions. This paper summarizes key trends in population size, fertility and mortality, and age structures during these transitions. The focus is on the century from 1950 to 2050, which covers the period of most rapid global demographic transformation. PMID:19770150

  2. Understanding China's Demographic Dividends and Labor Issue

    ERIC Educational Resources Information Center

    Peng, Xizhe

    2013-01-01

    One of the major concerns about the one-child policy is its negative impact on the current and future labor force in China. People have talked about the Lewis Turning Point and the end of demographic dividends. Some of these arguments, however, can be misleading. The working-age population (ages 15 to 59) can be treated as the potential labor…

  3. [Demographic transition at the epoch of industrialization].

    PubMed

    Billig, W

    1984-01-01

    The relationship between the early stages of industrialization and population factors in the United Kingdom, France, and the United States is analyzed from a Marxist perspective. The author attempts to associate successive phases of industrialization with phases of the demographic transition. He concludes that no comprehensive general theory concerning this relationship has been established. (summary in ENG, RUS) PMID:12266382

  4. Demographic development in ASEAN: a comparative overview.

    PubMed

    Herrin, A N; Pardoko, H; Lim, L L; Hongladorom, C

    1981-01-01

    A comparative overview of recent demographic developments in the ASEAN (Association of Southeast Asian Nations) region is presented. Countries discussed include Indonesia, Malaysia, the Philippines, Singapore, and Thailand. Separate consideration is given to mortality; fertility; and migration, spatial distribution, and employment. A final section is concerned with emerging issues and directions for population policy.

  5. Psychological and Demographic Correlates of Career Patterns

    ERIC Educational Resources Information Center

    Reitzle, Matthias; Korner, Astrid; Vondracek, Fred W.

    2009-01-01

    Recent years have witnessed a growing diversity of career patterns, resulting from the relative decline of stable employment. In the present study of 1368 employed and self-employed German adults career pattern diversity was assessed using nine pictograms. The goal was to identify psychological and demographic correlates of these patterns and to…

  6. Culture - joint fluid

    MedlinePlus

    Joint fluid culture ... fungi, or viruses grow. This is called a culture. If these germs are detected, other tests may ... is no special preparation needed for the lab culture. How to prepare for the removal of joint ...

  7. Temporomandibular Joint Dysfunction

    MedlinePlus

    The temporomandibular joint (TMJ) connects your jaw to the side of your head. When it works well, it enables you to ... For people with TMJ dysfunction, problems with the joint and muscles around it may cause Pain that ...

  8. Large displacement spherical joint

    DOEpatents

    Bieg, Lothar F.; Benavides, Gilbert L.

    2002-01-01

    A new class of spherical joints has a very large accessible full cone angle, a property which is beneficial for a wide range of applications. Despite the large cone angles, these joints move freely without singularities.

  9. Hip joint replacement

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002975.htm Hip joint replacement To use the sharing features on this page, please enable JavaScript. Hip joint replacement is surgery to replace all or part ...

  10. Missed Policy Opportunities to Advance Health Equity by Recording Demographic Data in Electronic Health Records

    PubMed Central

    Dawes, Daniel E.; Holden, Kisha B.; Mack, Dominic

    2015-01-01

    The science of eliminating health disparities is complex and dependent on demographic data. The Health Information Technology for Economic and Clinical Health Act (HITECH) encourages the adoption of electronic health records and requires basic demographic data collection; however, current data generated are insufficient to address known health disparities in vulnerable populations, including individuals from diverse racial and ethnic backgrounds, with disabilities, and with diverse sexual identities. We conducted an administrative history of HITECH and identified gaps between the policy objective and required measure. We identified 20 opportunities for change and 5 changes, 2 of which required the collection of less data. Until health care demographic data collection requirements are consistent with public health requirements, the national goal of eliminating health disparities cannot be realized. PMID:25905840

  11. Sacroiliac joint pain: anatomy, biomechanics, diagnosis, and treatment.

    PubMed

    Foley, Brian S; Buschbacher, Ralph M

    2006-12-01

    The sacroiliac joint is an underappreciated cause of low back and buttock pain. It is thought to cause at least 15% of low back pain. It is more common in the presence of trauma, pregnancy, or in certain athletes. The pelvic anatomy is complex, with the joint space being variable and irregular. The joint transmits vertical forces from the spine to the lower extremities and has a role in lumbopelvic dynamic motion. History and physical examination findings can be helpful in screening for sacroiliac joint pain, but individual provocative maneuvers have unproven validity. Fluoroscopically guided injections into the joint have been found to be helpful for diagnostic and therapeutic purposes. Conservative treatment, which also can include joint mobilization, antiinflammatory medicines, and sacroiliac joint belts, generally is effective. Surgical arthrodesis should be considered a procedure of last resort.

  12. [Total temporomandibular joint prostheses].

    PubMed

    Zwetyenga, N; Amroun, S; Wajszczak, B-L; Moris, V

    2016-09-01

    The temporomandibular joint (TMJ) is probably the most complex human joint. As in all joints, its prosthetic replacement may be indicated in selected cases. Significant advances have been made in the design of TMJ prostheses during the last three decades and the indications have been clarified. The aim of our work was to make an update on the current total TMJ total joint replacement. Indications, contraindications, prosthetic components, advantages, disadvantages, reasons for failure or reoperation, virtual planning and surgical protocol have been exposed.

  13. Progressive Damage Analysis of Bonded Composite Joints

    NASA Technical Reports Server (NTRS)

    Leone, Frank A., Jr.; Girolamo, Donato; Davila, Carlos G.

    2012-01-01

    The present work is related to the development and application of progressive damage modeling techniques to bonded joint technology. The joint designs studied in this work include a conventional composite splice joint and a NASA-patented durable redundant joint. Both designs involve honeycomb sandwich structures with carbon/epoxy facesheets joined using adhesively bonded doublers.Progressive damage modeling allows for the prediction of the initiation and evolution of damage within a structure. For structures that include multiple material systems, such as the joint designs under consideration, the number of potential failure mechanisms that must be accounted for drastically increases the complexity of the analyses. Potential failure mechanisms include fiber fracture, intraply matrix cracking, delamination, core crushing, adhesive failure, and their interactions. The bonded joints were modeled using highly parametric, explicitly solved finite element models, with damage modeling implemented via custom user-written subroutines. Each ply was discretely meshed using three-dimensional solid elements. Layers of cohesive elements were included between each ply to account for the possibility of delaminations and were used to model the adhesive layers forming the joint. Good correlation with experimental results was achieved both in terms of load-displacement history and the predicted failure mechanism(s).

  14. Joint Enrollment Report, 2014

    ERIC Educational Resources Information Center

    Iowa Department of Education, 2014

    2014-01-01

    The Iowa Department of Education collects information on joint enrollment in Iowa's 15 community colleges. Jointly enrolled students are high school students enrolled in community college credit coursework. Most jointly enrolled students enroll through Senior Year Plus (SYP) programs such as Postsecondary Enrollment Options (PSEO) and concurrent…

  15. Arch & Chord Joint Detail; Crossbracing Center Joint Detail; Chord, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Arch & Chord Joint Detail; Crossbracing Center Joint Detail; Chord, Panel Post, Tie & Diagonal Brace Joint Detail; Chord, Panel Post, Tie & Crossbracing Joint Detail - Dunlapsville Covered Bridge, Spanning East Fork Whitewater River, Dunlapsville, Union County, IN

  16. Family History

    MedlinePlus

    Your family history includes health information about you and your close relatives. Families have many factors in common, including their genes, ... as heart disease, stroke, and cancer. Having a family member with a disease raises your risk, but ...

  17. Joint custody: preliminary impressions.

    PubMed

    Awad, G A

    1983-02-01

    Joint custody is currently a popular and debatable issue. It is felt that some of the controversy is due to the lack of agreement on a definition. Following some examples of the differences in personal and judicial definitions of joint custody, a classification of custody is offered. Four types of custody arrangements are described: Absolute Sole Custody, Sole Custody, Non-Alternating Joint Custody (disputed and undisputed) and Alternating Joint Custody (disputed and undisputed). A critical review of the literature follows. Finally, clinical impressions about the two types of joint custody are discussed. PMID:6839267

  18. One-year outcomes after minimally invasive sacroiliac joint fusion with a series of triangular implants: a multicenter, patient-level analysis

    PubMed Central

    Sachs, Donald; Capobianco, Robyn; Cher, Daniel; Holt, Timothy; Gundanna, Mukund; Graven, Timothy; Shamie, A Nick; Cummings, John

    2014-01-01

    Background Sacroiliac joint (SI) pain is an often-overlooked cause of lower-back pain, due in part to a lack of specific findings on radiographs and a symptom profile similar to other back-related disorders. A minimally invasive surgical (MIS) approach to SI joint fusion using a series of triangular, titanium plasma spray-coated implants has shown favorable outcomes in patients with SI joint pain refractory to conservative care. The aim of this study was to provide a multicenter experience of MIS SI joint fusion using a patient-level analysis. Patients and methods We report a patient-level analysis from 144 patients with a mean of 16 months postoperative follow-up. Demographic information, perioperative measures, complications, and clinical outcomes using a visual analog scale for pain were collected prospectively. Random-effects regression models were used to account for intersite variability. Results The mean age was 58 years, 71% of patients were female, and 62% had a history of lumbar spinal fusion. Mean (95% confidence interval [CI]) operative time was 73 minutes (25.4–118), blood loss was minimal, and hospital stay was 0.8 days (0.1–1.5). At follow-up, mean (95% CI) visual analog scale pain scores improved by 6.1 points (5.7–6.6). Substantial clinical benefit, defined as a decrease in pain by >2.5 points or a score of 3.5 or less, was achieved in 91.9% of patients (95% CI 83.9%–96.1%), and 96% (95% CI 86.3%–98.8%) of patients indicated they would have the same surgery again. Conclusion When conservative measures fail to relieve symptoms resulting from degeneration or disruption of the SI joint, MIS SI joint fusion using a series of triangular, porous, titanium plasma spray-coated implants is a safe and effective treatment option. PMID:25210479

  19. Demographic variation in the U.K. serotine bat: filling gaps in knowledge for management

    PubMed Central

    Chauvenet, Alienor L M; Hutson, Anthony M; Smith, Graham C; Aegerter, James N

    2014-01-01

    Species of conservation concern, or those in conflict with man, are most efficiently managed with an understanding of their population dynamics. European bats exemplify the need for successful and cost-effective management for both reasons, often simultaneously. Across Europe, bats are protected, and the concept of Favourable Conservation Status (FCS) is used as a key tool for the assessment and licensing of disruptive actions to populations. However, for efficient decision-making, this assessment requires knowledge on the demographic rates and long-term dynamics of populations. We used capture–mark–recapture to describe demographic rates for the Serotine bat (Eptesicus serotinus) at two sites in England and investigate the transition rates between three stages: juveniles, immatures, and breeders. We then use these rates in an individual-based population dynamics model to investigate the expected trajectories for both populations. Our results demonstrate for the first time the presence and scale of temporal variation in this species' demography. We describe the lengthy prereproductive period (3.5 years) that female Serotines experience. Finally, we show how site-specific variation in demographic rates can produce divergent population trajectories. Effective management of European bat populations can be achieved through the understanding of life histories, and local demographic rates and population dynamics, in order to anticipate the presence of source and sink sites in the landscape. Using the Serotine bat in England, we show that these can be obtained from rigorous and systematic studies of long-term demographic datasets. PMID:25614796

  20. Demographics and respiratory illness prevalence of sport scuba divers.

    PubMed

    Tetzlaff, K; Muth, C M

    2005-09-01

    This study aimed to establish epidemiological data on diving habits and outcome of subjects with respiratory diseases who are considered at increased risk for diving injuries. We conducted a cross-sectional demographics and prevalence study by distribution of an anonymous questionnaire with an issue of a widespread sport diving magazine. The questionnaire was designed to obtain medical and diving history data with an emphasis on respiratory diseases and complaints. The investigational population comprised sport scuba divers of any age and gender from Austria, Germany, and Switzerland. Two hundred and twenty-six male and 96 female divers sent completed questionnaires. Of the respondents 8.7 % indicated that they currently have asthma. Two thirds of asthmatics complained about regular dyspnoea. However, only 42.4 % used drugs relieving or controlling their symptoms regularly and 27.3 % used them in a prophylactic manner before diving. Five percent and 4.7 % of all divers reported a history of respiratory disease other than asthma or dyspnoea respectively. The divers with respiratory illness or complaints had logged a total of 17,386 dives. There were no cases of serious diving injuries. Despite the well-known limitations of postal surveys assessing self reported data, this study indicates that there is a population of subjects diving uneventfully with respiratory diseases that are considered medical contraindications to diving. These subjects deserve particular guidance on related risks and disease management.

  1. New Approaches to Demographic Data Collection

    PubMed Central

    Treiman, Donald J.; Lu, Yao; Qi, Yaqiang

    2013-01-01

    As population scientists have expanded the range of topics they study, increasingly considering the interrelationship between population phenomena and social, economic, and health conditions, they have expanded the kinds of data collected and have brought to bear new data collection techniques and procedures, often borrowed from other fields. These new approaches to demographic data collection are the concern of this essay. We consider three main topics: new developments in sampling procedures; new developments in fieldwork procedures; and new developments in the kind of information collected in demographic and social surveys. We conclude with some comments on data sharing in the social research community and a list of major Chinese surveys publicly available to researchers. Where possible we illustrate our points with Chinese examples. PMID:23844330

  2. Modeling the evolutionary demographic processes for geomedicine

    NASA Astrophysics Data System (ADS)

    Lushnikov, A. A.; Kagan, A. I.; Gvishiani, A. D.; Lyubovtseva, Yu. S.

    2014-12-01

    We describe the principles for constructing evolutionary demographic models for geomedical statistics. Several variants of evolutionary models are proposed: (1) a model of the evolution of a closed population taking into account distribution by age, (2) a model that takes into account the morbidity and difference in mortality for groups of patients and healthy individuals, (3) a model that takes into account the distribution of different age groups by fertile ability, (4) a migration model that takes into account the population exchange between several localities, and (5) a model of the propagation of infectious diseases. Each model depends on a group of parameters determined from the medical and demographic state of the population. We discuss the possible application of the proposed evolutionary models to geomedical statistics.

  3. Complexity and demographic explanations of cumulative culture.

    PubMed

    Querbes, Adrien; Vaesen, Krist; Houkes, Wybo

    2014-01-01

    Formal models have linked prehistoric and historical instances of technological change (e.g., the Upper Paleolithic transition, cultural loss in Holocene Tasmania, scientific progress since the late nineteenth century) to demographic change. According to these models, cumulation of technological complexity is inhibited by decreasing--while favoured by increasing--population levels. Here we show that these findings are contingent on how complexity is defined: demography plays a much more limited role in sustaining cumulative culture in case formal models deploy Herbert Simon's definition of complexity rather than the particular definitions of complexity hitherto assumed. Given that currently available empirical evidence doesn't afford discriminating proper from improper definitions of complexity, our robustness analyses put into question the force of recent demographic explanations of particular episodes of cultural change.

  4. Some demographic issues affecting private health insurance.

    PubMed

    Hanning, Brian

    2004-01-01

    There will be significant changes in the demography of persons with Private Health Insurance (PHI). Two methods of projecting PHI coverage are discussed in this paper. The first assumes the only factors affecting PHI coverage are demographic change and mortality and facilitates comparisons between actual and projected PHI coverage. The second projects the percentage of the population insured in each five year age cohort, and makes allowance for changes in PHI coverage due to all factors. Demographic change will increase Registered Health Benefit Organization (RHBO) premiums by 1.7% per annum. The role of these projections in analysing the effect of future premium increases on PHI retention rates is also discussed. PMID:15362293

  5. Is the demographic dividend an education dividend?

    PubMed

    Crespo Cuaresma, Jesús; Lutz, Wolfgang; Sanderson, Warren

    2014-02-01

    The effect of changes in age structure on economic growth has been widely studied in the demography and population economics literature. The beneficial effect of changes in age structure after a decrease in fertility has become known as the "demographic dividend." In this article, we reassess the empirical evidence on the associations among economic growth, changes in age structure, labor force participation, and educational attainment. Using a global panel of countries, we find that after the effect of human capital dynamics is controlled for, no evidence exists that changes in age structure affect labor productivity. Our results imply that improvements in educational attainment are the key to explaining productivity and income growth and that a substantial portion of the demographic dividend is an education dividend.

  6. Population momentum across the demographic transition.

    PubMed

    Blue, Laura; Espenshade, Thomas J

    2011-01-01

    Population momentum is the main driver of global population growth today, and this makes an appreciation of momentum critical to understanding contemporary worldwide growth dynamics. This article traces population momentum along with two recently defined measures of momentum decomposed—stable and nonstable momentum—across the demographic transition. We use historical data and population projections from 16 countries to illustrate some previously ignored empirical regularities of the demographic transition in both the developed and the developing world. We also demonstrate the dynamic nature of stable and nonstable momentum, as changes in stable momentum lead to predictable changes in current and future nonstable momentum. These results suggest that momentum, which by definition is measured at a point in time, can also be considered as a process that unfolds over time.

  7. Individual heterogeneity in life histories and eco-evolutionary dynamics

    PubMed Central

    Vindenes, Yngvild; Langangen, Øystein

    2015-01-01

    Individual heterogeneity in life history shapes eco-evolutionary processes, and unobserved heterogeneity can affect demographic outputs characterising life history and population dynamical properties. Demographic frameworks like matrix models or integral projection models represent powerful approaches to disentangle mechanisms linking individual life histories and population-level processes. Recent developments have provided important steps towards their application to study eco-evolutionary dynamics, but so far individual heterogeneity has largely been ignored. Here, we present a general demographic framework that incorporates individual heterogeneity in a flexible way, by separating static and dynamic traits (discrete or continuous). First, we apply the framework to derive the consequences of ignoring heterogeneity for a range of widely used demographic outputs. A general conclusion is that besides the long-term growth rate lambda, all parameters can be affected. Second, we discuss how the framework can help advance current demographic models of eco-evolutionary dynamics, by incorporating individual heterogeneity. For both applications numerical examples are provided, including an empirical example for pike. For instance, we demonstrate that predicted demographic responses to climate warming can be reversed by increased heritability. We discuss how applications of this demographic framework incorporating individual heterogeneity can help answer key biological questions that require a detailed understanding of eco-evolutionary dynamics. PMID:25807980

  8. Temporomandibular joint osteoarthrosis and temporomandibular joint hypermobility.

    PubMed

    Dijkstra, P U; de Bont, L G; de Leeuw, R; Stegenga, B; Boering, G

    1993-10-01

    For studying the relationship between condylar hypermobility of the temporomandibular joint (TMJ) and osteoarthrosis (OA), 13 patients with bilateral condylar hypermobility were evaluated clinically and radiographically, 30 years after non-surgical treatment. The evaluation included range of motion, joint and muscle tenderness to palpation, joint sounds and masticatory function. Radiographs of the TMJs were evaluated for the absence or presence of degenerative changes. The hypermobile group (HG) was compared with a control group (CG) (n = 13). The CG was evaluated in the same way as the HG. Statistics included t-tests (to compare ranges of motion in the HG over time and to compare ranges of motion in HG and CG), non-parametric tests (to compare tenderness of muscles and joints, joint sounds, masticatory function and radiographic changes over time in the HG). The tests were also used to compare the same variables between the HG and CG group. The groups' only difference was the presence of radiographic signs of OA. In the HG the number of joints with radiographic degenerative changes increased significantly over time and was significantly higher than the CG. Clinically and functionally, the HG and CG did not differ. Therefore, it is concluded that TMJ hypermobility is a subsidiary factor in the development of TMJ OA. PMID:8118897

  9. [[Demographic characteristics of "business bachelors" in Japan

    PubMed

    Yamamoto, C

    1987-01-01

    The demographic characteristics of those obliged to live away from their families because of the distance between their normal homes and places of work or education in Japan are described. Data are from a variety of official and other sources. The author notes that such persons are generally male. Factors affecting the growth of this phenomenon in Japan are the concept of lifetime employment with the same company and the popularity of sending children away to school.

  10. Soft Selective Sweeps in Complex Demographic Scenarios

    PubMed Central

    Wilson, Benjamin A.; Petrov, Dmitri A.; Messer, Philipp W.

    2014-01-01

    Adaptation from de novo mutation can produce so-called soft selective sweeps, where adaptive alleles of independent mutational origin sweep through the population at the same time. Population genetic theory predicts that such soft sweeps should be likely if the product of the population size and the mutation rate toward the adaptive allele is sufficiently large, such that multiple adaptive mutations can establish before one has reached fixation; however, it remains unclear how demographic processes affect the probability of observing soft sweeps. Here we extend the theory of soft selective sweeps to realistic demographic scenarios that allow for changes in population size over time. We first show that population bottlenecks can lead to the removal of all but one adaptive lineage from an initially soft selective sweep. The parameter regime under which such “hardening” of soft selective sweeps is likely is determined by a simple heuristic condition. We further develop a generalized analytical framework, based on an extension of the coalescent process, for calculating the probability of soft sweeps under arbitrary demographic scenarios. Two important limits emerge within this analytical framework: In the limit where population-size fluctuations are fast compared to the duration of the sweep, the likelihood of soft sweeps is determined by the harmonic mean of the variance effective population size estimated over the duration of the sweep; in the opposing slow fluctuation limit, the likelihood of soft sweeps is determined by the instantaneous variance effective population size at the onset of the sweep. We show that as a consequence of this finding the probability of observing soft sweeps becomes a function of the strength of selection. Specifically, in species with sharply fluctuating population size, strong selection is more likely to produce soft sweeps than weak selection. Our results highlight the importance of accurate demographic estimates over short

  11. The demographic cycle and optimal schooling choices.

    PubMed

    Jeon, B P; Berger, M C

    1996-10-01

    A model is developed that enables the authors to estimate the effects of demographic cycles on both earnings and schooling. The model is tested using data from the 1991 Korean Occupational Wage Survey. The results indicate that cohorts following large birth cohorts in the cycle choose relatively less formal schooling compared to pre-peak cohorts, and that post-peak cohorts also have lower incomes. This result concerning South Korea is consistent with findings from previous studies concerning the United States.

  12. Stochastic game dynamics under demographic fluctuations.

    PubMed

    Huang, Weini; Hauert, Christoph; Traulsen, Arne

    2015-07-21

    Frequency-dependent selection and demographic fluctuations play important roles in evolutionary and ecological processes. Under frequency-dependent selection, the average fitness of the population may increase or decrease based on interactions between individuals within the population. This should be reflected in fluctuations of the population size even in constant environments. Here, we propose a stochastic model that naturally combines these two evolutionary ingredients by assuming frequency-dependent competition between different types in an individual-based model. In contrast to previous game theoretic models, the carrying capacity of the population, and thus the population size, is determined by pairwise competition of individuals mediated by evolutionary games and demographic stochasticity. In the limit of infinite population size, the averaged stochastic dynamics is captured by deterministic competitive Lotka-Volterra equations. In small populations, demographic stochasticity may instead lead to the extinction of the entire population. Because the population size is driven by fitness in evolutionary games, a population of cooperators is less prone to go extinct than a population of defectors, whereas in the usual systems of fixed size the population would thrive regardless of its average payoff. PMID:26150518

  13. Rural Household Demographics, Livelihoods and the Environment

    PubMed Central

    de Sherbinin, Alex; VanWey, Leah; McSweeney, Kendra; Aggarwal, Rimjhim; Barbieri, Alisson; Henry, Sabina; Hunter, Lori M.; Twine, Wayne

    2008-01-01

    This paper reviews and synthesizes findings from scholarly work on linkages among rural household demographics, livelihoods and the environment. Using the livelihood approach as an organizing framework, we examine evidence on the multiple pathways linking environmental variables and the following demographic variables: fertility, migration, morbidity and mortality, and lifecycles. Although the review draws on studies from the entire developing world, we find the majority of micro-level studies have been conducted in either marginal (mountainous or arid) or frontier environments, especially Amazonia. Though the linkages are mediated by many complex and often context-specific factors, there is strong evidence that dependence on natural resources intensifies when households lose human and social capital through adult morbidity and mortality, and qualified evidence for the influence of environmental factors on household decision-making regarding fertility and migration. Two decades of research on lifecycles and land-cover change at the farm level have yielded a number of insights about how households make use of different land-use and natural resource management strategies at different stages. A thread running throughout the review is the importance of managing risk through livelihood diversification, ensuring future income security, and culture-specific norms regarding appropriate and desirable activities and demographic responses. Recommendations for future research are provided. PMID:19190718

  14. Rural Household Demographics, Livelihoods and the Environment.

    PubMed

    de Sherbinin, Alex; Vanwey, Leah; McSweeney, Kendra; Aggarwal, Rimjhim; Barbieri, Alisson; Henry, Sabina; Hunter, Lori M; Twine, Wayne

    2008-02-01

    This paper reviews and synthesizes findings from scholarly work on linkages among rural household demographics, livelihoods and the environment. Using the livelihood approach as an organizing framework, we examine evidence on the multiple pathways linking environmental variables and the following demographic variables: fertility, migration, morbidity and mortality, and lifecycles. Although the review draws on studies from the entire developing world, we find the majority of micro-level studies have been conducted in either marginal (mountainous or arid) or frontier environments, especially Amazonia. Though the linkages are mediated by many complex and often context-specific factors, there is strong evidence that dependence on natural resources intensifies when households lose human and social capital through adult morbidity and mortality, and qualified evidence for the influence of environmental factors on household decision-making regarding fertility and migration. Two decades of research on lifecycles and land-cover change at the farm level have yielded a number of insights about how households make use of different land-use and natural resource management strategies at different stages. A thread running throughout the review is the importance of managing risk through livelihood diversification, ensuring future income security, and culture-specific norms regarding appropriate and desirable activities and demographic responses. Recommendations for future research are provided.

  15. Entropy Based Modelling for Estimating Demographic Trends.

    PubMed

    Li, Guoqi; Zhao, Daxuan; Xu, Yi; Kuo, Shyh-Hao; Xu, Hai-Yan; Hu, Nan; Zhao, Guangshe; Monterola, Christopher

    2015-01-01

    In this paper, an entropy-based method is proposed to forecast the demographical changes of countries. We formulate the estimation of future demographical profiles as a constrained optimization problem, anchored on the empirically validated assumption that the entropy of age distribution is increasing in time. The procedure of the proposed method involves three stages, namely: 1) Prediction of the age distribution of a country's population based on an "age-structured population model"; 2) Estimation the age distribution of each individual household size with an entropy-based formulation based on an "individual household size model"; and 3) Estimation the number of each household size based on a "total household size model". The last stage is achieved by projecting the age distribution of the country's population (obtained in stage 1) onto the age distributions of individual household sizes (obtained in stage 2). The effectiveness of the proposed method is demonstrated by feeding real world data, and it is general and versatile enough to be extended to other time dependent demographic variables. PMID:26382594

  16. Temporomandibular joint dislocation: experiences from Zaria, Nigeria

    PubMed Central

    Fomete, Benjamin; Obiadazie, Athanasius Chukwudi; Idehen, Kelvin; Okeke, Uche

    2014-01-01

    Objectives Dislocation of the temporomandibular joint may occur for various reasons. Although different invasive methods have been advocated for its treatment, this study highlights the value of non-invasive treatment options even in chronic cases in a resource-poor environment. Materials and Methods A seven-year retrospective analysis of all patients managed for temporomandibular joint dislocation in our department was undertaken. Patient demographics, risk factors associated with temporomandibular joint dislocation and treatment modalities were retrieved from patient records. Results In all, 26 patients were managed over a seven-year period. Males accounted for 62% of the patients, and yawning was the most frequent etiological factor. Conservative treatment methods were used successfully in 86.4% of the patients managed. Two (66.7%) of the three patients who needed surgical treatment developed complications, while only one (5.3%) patient who was managed conservatively developed complications. Conclusion Temporomandibular joint dislocation appears to be associated with male sex, middle age, yawning, and low socio-economic status, although these observed relationships were not statistically significant. Non-invasive methods remain an effective treatment option in this environment in view of the low socio-economic status of the patients affected. PMID:25045637

  17. Population history in the 1980s: the prospects for population history.

    PubMed

    Wrigley, E A

    1981-01-01

    Changes in the approach and scope of the study of population history over the past few decades are examined. The development of family reconstitution and aggregative back projection as techniques used in historical demography is described, and the impact of these techniques on the range of investigation of population history is considered. Changing awareness of the significance of the relationship between demographic change and the socioeconomic system and of the importance of studying analyzing marriage and reproductive patterns is discussed.

  18. Lunar History

    NASA Technical Reports Server (NTRS)

    Edmunson, Jennifer E.

    2009-01-01

    This section of the workshop describes the history of the moon, and offers explanations for the importance of understanding lunar history for engineers and users of lunar simulants. Included are summaries of the initial impact that is currently in favor as explaining the moon's formation, the crust generation, the creation of craters by impactors, the era of the lunar cataclysm, which some believe effected the evolution of life on earth, the nature of lunar impacts, crater morphology, which includes pictures of lunar craters that show the different types of craters, more recent events include effect of micrometeorites, solar wind, radiation and generation of agglutinates. Also included is a glossary of terms.

  19. Joint hypermobility leading to osteoarthrosis and chondrocalcinosis.

    PubMed

    Bird, H A; Tribe, C R; Bacon, P A

    1978-06-01

    We have reviewed 21 adults referred to rheumatology clinic and considered to have generalised joint hypermobility by the criteria of Carter and Wilkinson (1964), modified by Beighton et al. (1973). They fell into two categories. 5 patients had a raised plasma viscosity (PV) and in each case a definite pathology was found to account for this, superimposed on hypermobile joints. The remaining 16 had a normal PV and this group was thought to represent the late natural history of hypermobility. 5 of these (aged 32 to 54 years) had no evidence of osteoarthrosis but the remaining 11 (aged 34 to 80 years) had widespread radiological osteoarthrosis. Synovial histology was obtained at arthroscopy in 6 of these patients and 4 (aged 60 to 75) had chondrocalcinosis. This previously undescribed finding may be the end result of hypermobile joints. Hypermobile patients with joint deformity (lax connective tissue), widespread synovial thickening (traumatic), and hot joint effusions (chondrocalcinosis) may mimic rheumatoid arthritis. They must be distinguished from patients who develop rheumatoid arthritis in hypermobile joints.

  20. Demographic and Clinical Characteristics of People with Intellectual Disabilities with and without Substance Abuse Disorders in a Medicaid Population

    ERIC Educational Resources Information Center

    Slayter, Elspeth Maclean

    2010-01-01

    Little is known about the demographic and clinical characteristics of people with intellectual disabilities and substance abuse problems. Drawing on health care billing claims for people with Medicaid coverage aged 12-99 years, the characteristics of people with intellectual disability and a history of substance abuse (N = 9,484) were explored and…

  1. DEMOGRAPHIC UNCERTAINTY IN ECOLOGICAL RISK ASSESSMENTS. (R825347)

    EPA Science Inventory

    We built a Ricker's model incorporating demographic stochasticity to simulate the effects of demographic uncertainty on responses of gray-tailed vole (Microtus canicaudus) populations to pesticide applications. We constructed models with mark-recapture data collected from populat...

  2. Simulating the Structural Response of a Preloaded Bolted Joint

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Phillips, Dawn R.; Raju, Ivatury S.

    2008-01-01

    The present paper describes the structural analyses performed on a preloaded bolted-joint configuration. The joint modeled was comprised of two L-shaped structures connected together using a single bolt. Each L-shaped structure involved a vertical flat segment (or shell wall) welded to a horizontal segment (or flange). Parametric studies were performed using elasto-plastic, large-deformation nonlinear finite element analyses to determine the influence of several factors on the bolted-joint response. The factors considered included bolt preload, washer-surface-bearing size, edge boundary conditions, joint segment length, and loading history. Joint response is reported in terms of displacements, gap opening, and surface strains. Most of the factors studied were determined to have minimal effect on the bolted-joint response; however, the washer-bearing-surface size affected the response significantly.

  3. Arguing History

    ERIC Educational Resources Information Center

    Clary, Renee; Wandersee, James

    2013-01-01

    The history of science illustrates some exciting--and sometimes controversial--moments. Unfortunately, textbooks tend to focus on results in a scientific discipline and only occasionally showcase an interesting historical vignette, telling the story behind those results. Although required studies may leave teachers little classroom time for…

  4. Minting History.

    ERIC Educational Resources Information Center

    Kohl, Gary

    2003-01-01

    Presents a project where fourth-grade students depicted images on coins to reflect important conflicts in Canadian history, such as September 11, 2001. Explains how to create the coins in detail. States that the students each wrote a "proclamation" that described their time period depicted on the coins. (CMK)

  5. Why History?

    ERIC Educational Resources Information Center

    Duffy, Robert E.

    1988-01-01

    Examines the way in which studying history contributes to intellectual development. Identifies five mental attributes it enhances: perspective--gained from placing people, events, institutions against larger background; encounter--confronting great ideas, personalities, etc.; relativism in a pluralistic world--developed from immersion in other…

  6. Making History

    ERIC Educational Resources Information Center

    Shein, Esther

    2008-01-01

    Jennifer Dorman was in a fix. Teaching ninth-grade US history at Holicong Middle School in Doylestown, Pennsylvania, Dorman wanted to tap into her students' interest in creating "something of value not just for their teachers, but something they could share with other students and people." But that required something a conventional paper-based…

  7. Humanistic History.

    ERIC Educational Resources Information Center

    Marrow, Alvin J.

    1982-01-01

    Utilizing the theories of McGregor, Maslow, and Herzberg, presents a model for teaching history which involves students in designing their own course objectives. Includes humanistic approaches, organizational management assumptions, and models with motivational, hygiene, physiological, and safety factors. (DMM)

  8. [Total temporomandibular joint prostheses].

    PubMed

    Zwetyenga, N; Amroun, S; Wajszczak, B-L; Moris, V

    2016-09-01

    The temporomandibular joint (TMJ) is probably the most complex human joint. As in all joints, its prosthetic replacement may be indicated in selected cases. Significant advances have been made in the design of TMJ prostheses during the last three decades and the indications have been clarified. The aim of our work was to make an update on the current total TMJ total joint replacement. Indications, contraindications, prosthetic components, advantages, disadvantages, reasons for failure or reoperation, virtual planning and surgical protocol have been exposed. PMID:27554487

  9. Patterns of demographic change in the Americas.

    PubMed

    Ubelaker, D H

    1992-06-01

    Considerable scholarly debate has focused on the nature of demographic change in the Americas before and after 1492. Recent research on human skeletal samples and related archeological materials suggests that morbidity and mortality were increasing throughout much of the Western Hemisphere before 1492 in response to increased population density, increased sedentism, and changing subsistence. The evidence suggests that after 1492 population reduction was caused not by continental pandemics but by localized or regional epidemics augmented by social and economic disruption. The twentieth century has witnessed remarkable Native American population recovery, fueled both by improvements in health care and changing definitions of "being Indian."

  10. History of San Marco

    NASA Technical Reports Server (NTRS)

    Caporale, A. J.

    1968-01-01

    A brief history is reported of the first San Marco project, a joint program of the United States and Italy. The Project was a three phase effort to investigate upper air density and associated ionosphere phenomena. The initial phase included the design and development of the spacecraft, the experiments, the launch complex, and a series of suborbital flights, from Wallops Island. The second phase, consisting of designing, fabricating, and testing a spacecraft for the first orbital mission, culminated in an orbital launch also from Wallops Island. The third phase consisted of further refining the experiments and spacecraft instrumentation and of establishing a full-bore scout complex in Kenya. The launch of San Marco B, in April 1967, from this complex into an equatorial orbit, concluded the initial San Marco effort.

  11. Climatic conditions cause complex patterns of covariation between demographic traits in a long-lived raptor.

    PubMed

    Herfindal, Ivar; van de Pol, Martijn; Nielsen, Jan T; Sæther, Bernt-Erik; Møller, Anders P

    2015-05-01

    Environmental variation can induce life-history changes that can last over a large part of the lifetime of an organism. If multiple demographic traits are affected, expected changes in climate may influence environmental covariances among traits in a complex manner. Thus, examining the consequences of environmental fluctuations requires that individual information at multiple life stages is available, which is particularly challenging in long-lived species. Here, we analyse how variation in climatic conditions occurring in the year of hatching of female goshawks Accipiter gentilis (L.) affects age-specific variation in demographic traits and lifetime reproductive success (LRS). LRS decreased with increasing temperature in April in the year of hatching, due to lower breeding frequency and shorter reproductive life span. In contrast, the probability for a female to successfully breed was higher in years with a warm April, but lower LRS of the offspring in these years generated a negative covariance among fecundity rates among generations. The mechanism by which climatic conditions generated cohort effects was likely through influencing the quality of the breeding segment of the population in a given year, as the proportion of pigeons in the diet during the breeding period was positively related to annual and LRS, and the diet of adult females that hatched in warm years contained fewer pigeons. Climatic conditions experienced during different stages of individual life histories caused complex patterns of environmental covariance among demographic traits even across generations. Such environmental covariances may either buffer or amplify impacts of climate change on population growth, emphasizing the importance of considering demographic changes during the complete life history of individuals when predicting the effect of climatic change on population dynamics of long-lived species.

  12. Mechanics of Sheeting Joints

    NASA Astrophysics Data System (ADS)

    Martel, S. J.

    2015-12-01

    Physical breakdown of rock across a broad scale spectrum involves fracturing. In many areas large fractures develop near the topographic surface, with sheeting joints being among the most impressive. Sheeting joints share many geometric, textural, and kinematic features with other joints (opening-mode fractures) but differ in that they are (a) discernibly curved, (b) open near the topographic surface, and (c) form subparallel to the topographic surface. Where sheeting joints are geologically young, the surface-parallel compressive stresses are typically several MPa or greater. Sheeting joints are best developed beneath domes, ridges, and saddles; they also are reported, albeit rarely, beneath valleys or bowls. A mechanism that accounts for all these associations has been sought for more than a century: neither erosion of overburden nor high lateral compressive stresses alone suffices. Sheeting joints are not accounted for by Mohr-Coulomb shear failure criteria. Principles of linear elastic fracture mechanics, together with the mechanical effect of a curved topographic surface, do provide a basis for understanding sheeting joint growth and the pattern sheeting joints form. Compressive stresses parallel to a singly or doubly convex topographic surface induce a tensile stress perpendicular to the surface at shallow depths; in some cases this alone could overcome the weight of overburden to open sheeting joints. If regional horizontal compressive stresses, augmented by thermal stresses, are an order of magnitude or so greater than a characteristic vertical stress that scales with topographic amplitude, then topographic stress perturbations can cause sheeting joints to open near the top of a ridge. This topographic effect can be augmented by pressure within sheeting joints arising from water, ice, or salt. Water pressure could be particularly important in helping drive sheeting joints downslope beneath valleys. Once sheeting joints have formed, the rock sheets between

  13. The Diagnosis of Periprosthetic Joint Infection.

    PubMed

    Springer, Bryan D

    2015-06-01

    Periprosthetic joint infection remains one of the most common failure modes following total hip and total knee arthroplasty. As such, a systematic and cost effective approach to the evaluation and work-up of a patient with a suspected periprosthetic joint infection should be undertaken in every patient with a painful total joint. Although we have many diagnostic tools, a history and physical remain the most important. Many of the current laboratory tests are indirect measure of infection, lack specificity for diagnosis of infection, but serve as sensitive and cost effective screening tools. In addition, a new definition of periprosthetic infection helps to standardize the diagnosis. Biomarkers hold the promise of improved specificity and are becoming increasingly popular as a diagnostic tool.

  14. Infected shoulder joint with loose Suture Anchor in the joint after Bankart’s Repair- A Case Report

    PubMed Central

    Kumar, Mukesh; Thilak, Jai

    2016-01-01

    Introduction: The glenoid labrum is frequently torn in traumatic glenohumeral dislocation; arthroscopic repair is the standard method of treatment. The complications associated with this repair are pulling out of metal suture anchors, chondrolysis and joint infection. The infection of joint after arthroscopy is less than 1%. Staphylococcus is most common organism and rarely followed by Pseudomonas aeruginosa. We report a case of infected shoulder with chondrolysis of the joint and pulled out metal suture anchor lying inside the joint after Bankart’s repair. Case Report: A 22-year-old gentleman came to us with complaints of shoulder joint pain & gross restriction of movements for one year, with history of intermittent fever and treatment in nearby hospital. He also gives past history of recurrent dislocation of shoulder with last episode 18 months back, which was diagnosed as Bankart’s lesion and arthroscopic Bankart’s repair was done 15 months back. He was evaluated at our institute and suspected to have infection of shoulder joint with pulled out metal suture anchor inside the joint. Arthroscopic removal of suture anchor and debridement of shoulder joint was done, Culture was obtained and culture specific antibiotics were given for six weeks, and significant improvement was observed with this line of treatment. At lyear follow up, the patient was able to perform his daily activities with terminal restriction of range of motion. Conclusions: Shoulder joint infection is rare after Bankart’s repair and required a high degree of suspicion. Any foreign materials inside the joint should be taken out & followed with aggressive treatment by debridement, irrigation and culture specific antibiotics. Suppression of joint infection with antibiotics should be avoided specially when there is foreign body inside the joint.

  15. Household demographic determinants of Ebola epidemic risk.

    PubMed

    Adams, Ben

    2016-03-01

    A salient characteristic of Ebola, and some other infectious diseases such as Tuberculosis, is intense transmission among small groups of cohabitants and relatively limited indiscriminate transmission in the wider population. Here we consider a mathematical model for an Ebola epidemic in a population structured into households of equal size. We show that household size, a fundamental demographic unit, is a critical factor that determines the vulnerability of a community to epidemics, and the effort required to control them. Our analysis is based on the household reproduction number, but we also consider the basic reproduction number, intrinsic growth rate and final epidemic size. We show that, when other epidemiological parameters are kept the same, all of these quantifications of epidemic growth and size are increased by larger households and more intense within-household transmission. We go on to model epidemic control by case detection and isolation followed by household quarantine. We show that, if household quarantine is ineffective, the critical probability with which cases must be detected to halt an epidemic increases significantly with each increment in household size and may be a very challenging target for communities composed of large households. Effective quarantine may, however, mitigate the detrimental impact of large household sizes. We conclude that communities composed of large households are fundamentally more vulnerable to epidemics of infectious diseases primarily transmitted by close contact, and any assessment of control strategies for these epidemics should take into account the demographic structure of the population.

  16. Demographic dynamics and kinship in anthropological populations

    PubMed Central

    Hammel, E. A.

    2005-01-01

    Changes in fertility and mortality affect the size of surviving sibling sets and thus numbers of surviving kin. Because the genealogical generations specifying kinship relations are not temporal cohorts and most plausible demographic changes in anthropological populations are period shocks, the effect of such shocks on kin counts are complex. Shocks increasing fertility or decreasing mortality produce larger numbers of kin per ego and decrease the inequality of the distribution of kin and vice versa. Effects are more diffuse at more distant collateral ranges. Effects are stronger the more intense the shock and the longer its duration. Kinship distributions return to their initial state after the shock and as the original age structure of the population is ergodically reattained. Alternating shocks produce more complex patterns. Implications of these outcomes are that opportunities for political networking and consolidation by means of kinship are altered by demographic instabilities, as are the dynamics of kin selection. This analysis is limited for simplicity to unilineal agnatic reckoning of kin. PMID:15677714

  17. Material Stock Demographics: Cars in Great Britain.

    PubMed

    Cabrera Serrenho, André; Allwood, Julian M

    2016-03-15

    Recent literature on material flow analysis has been focused on quantitative characterization of past material flows. Fewer analyses exist on past and prospective quantification of stocks of materials in-use. Some of these analyses explore the composition of products' stocks, but a focus on the characterization of material stocks and its relation with service delivery is often neglected. We propose the use of the methods of human demography to characterize material stocks, defined herein as stock demographics, exploring the insights that this approach could provide for the sustainable management of materials. We exemplify an application of stock demographics by characterizing the composition and service delivery of iron, steel, and aluminum stocks of cars in Great Britain, 2002-2012. The results show that in this period the stock has become heavier, it is traveling less, and it is idle for more time. The visualization of material stocks' dynamics demonstrates the pace of product replacement as a function of its usefulness and enables the formulation of policy interventions and the exploration of future trends.

  18. Demographic correlates of attenuated positive psychotic symptoms

    PubMed Central

    Waford, Rachel N.; MacDonald, Allison; Goines, Katrina; Novacek, Derek M.; Trotman, Hanan D.; Walker, Elaine F.; Addington, Jean; Bearden, Carrie E.; Cadenhead, Kristin S.; Cannon, Tyrone D.; Cornblatt, Barbara A.; Heinssen, Robert; Mathalon, Daniel H.; Tsuang, Ming T.; Perkins, Diana O.; Seidman, Larry J.; Woods, Scott W.; McGlashan, Thomas H.

    2015-01-01

    It is now well established that the utilization of standardized clinical criteria can enhance prediction of psychosis. These criteria are primarily concerned with the presence and severity of attenuated positive symptoms. Because these symptom criteria are used to derive algorithms for designating clinical high risk (CHR) status and for maximizing prediction of psychosis risk, it is important to know whether the symptom ratings vary as a function of demographic factors that have previously been linked with symptoms in diagnosed psychotic patients. Using a sample of 356 CHR individuals from the NAPLS-II multi-site study, we examined the relation of three sex, age, and educational level, with the severity of attenuated positive symptom scores from the Scale of Prodromal Symptoms (SOPS). Demographic factors accounted for little of the variance in symptom ratings (5–6%). Older CHR individuals manifested more severe suspiciousness, and female CHR participants reported more unusual perceptual experiences than male participants. Contrary to prediction, higher educational level was associated with more severe ratings of unusual thought content, but less severe perceptual abnormalities. Overall, sex, age and education were modestly related to unusual thought content and perceptual abnormalities, only, suggesting minimal implication for designating CHR status and predicting psychosis-risk. PMID:25999040

  19. Compound solder joints

    NASA Technical Reports Server (NTRS)

    Batista, R. I.; Simonson, R. B.

    1976-01-01

    Joining technique prevents contamination, may be used to join dissimilar metal tubes, minimizes fluid and gas entrapment, expedites repairs, and can yield joints having leakage rates less than 0.000001 standard cubic cm He/min. Components of joint are solder sleeve, two solder rings, Teflon sleeve, and tubing to be joined.

  20. Truss Slip Joint

    NASA Technical Reports Server (NTRS)

    Thomas, Frank

    1993-01-01

    Truss slip joint has few parts, strong, and assembled and disassembled easily. Designed to carry axial loads as large as 100,000 lb and to accommodate slight initial axial-displacement and angular misalignments. Joint assembled or disassembled by astronaut in space suit or, on Earth, by technician in heavy protective clothing; simple enough to be operable by robot. Modified to accommodate welding.

  1. Wedge Joints for Trusses

    NASA Technical Reports Server (NTRS)

    Wood, Kenneth E.

    1987-01-01

    Structure assembled rapidly with simple hand tools. Proposed locking wedge joints enable rapid assembly of lightweight beams, towers, scaffolds, and other truss-type structures. Lightweight structure assembled from tubular struts joined at nodes by wedge pins fitting into mating slots. Joint assembled rapidly by seating wedge pin in V-shaped slots and deforming end of strut until primary pawl engages it.

  2. River history.

    PubMed

    Vita-Finzi, Claudio

    2012-05-13

    During the last half century, advances in geomorphology-abetted by conceptual and technical developments in geophysics, geochemistry, remote sensing, geodesy, computing and ecology-have enhanced the potential value of fluvial history for reconstructing erosional and depositional sequences on the Earth and on Mars and for evaluating climatic and tectonic changes, the impact of fluvial processes on human settlement and health, and the problems faced in managing unstable fluvial systems. PMID:22474674

  3. River history.

    PubMed

    Vita-Finzi, Claudio

    2012-05-13

    During the last half century, advances in geomorphology-abetted by conceptual and technical developments in geophysics, geochemistry, remote sensing, geodesy, computing and ecology-have enhanced the potential value of fluvial history for reconstructing erosional and depositional sequences on the Earth and on Mars and for evaluating climatic and tectonic changes, the impact of fluvial processes on human settlement and health, and the problems faced in managing unstable fluvial systems.

  4. An integrated framework for the inference of viral population history from reconstructed genealogies.

    PubMed Central

    Pybus, O G; Rambaut, A; Harvey, P H

    2000-01-01

    We describe a unified set of methods for the inference of demographic history using genealogies reconstructed from gene sequence data. We introduce the skyline plot, a graphical, nonparametric estimate of demographic history. We discuss both maximum-likelihood parameter estimation and demographic hypothesis testing. Simulations are carried out to investigate the statistical properties of maximum-likelihood estimates of demographic parameters. The simulations reveal that (i) the performance of exponential growth model estimates is determined by a simple function of the true parameter values and (ii) under some conditions, estimates from reconstructed trees perform as well as estimates from perfect trees. We apply our methods to HIV-1 sequence data and find strong evidence that subtypes A and B have different demographic histories. We also provide the first (albeit tentative) genetic evidence for a recent decrease in the growth rate of subtype B. PMID:10880500

  5. Demographic response of cutlassfish (Trichiurus japonicus and T. nanhaiensis) to fluctuating palaeo-climate and regional oceanographic conditions in the China seas

    NASA Astrophysics Data System (ADS)

    He, Lijun; Zhang, Aibing; Weese, David; Li, Shengfa; Li, Jiansheng; Zhang, Jing

    2014-09-01

    Glacial cycles of the Quaternary have heavily influenced the demographic history of various species. To test the evolutionary impact of palaeo-geologic and climatic events on the demographic history of marine taxa from the coastal Western Pacific, we investigated the population structure and demographic history of two economically important fish (Trichiurus japonicus and T. nanhaiensis) that inhabit the continental shelves of the East China and northern South China Seas using the mitochondrial cytochrome b sequences and Bayesian Skyline Plot analyses. A molecular rate of 2.03% per million years, calibrated to the earliest flooding of the East China Sea shelf (70-140 kya), revealed a strong correlation between population sizes and primary production. Furthermore, comparison of the demographic history of T. japonicus populations from the East China and South China Seas provided evidence of the postglacial development of the Changjiang (Yangtze River) Delta. In the South China Sea, interspecific comparisons between T. japonicus and T. nanhaiensis indicated possible evolutionary responses to changes in palaeo-productivity that were influenced by East Asian winter monsoons. This study not only provides insight into the demographic history of cutlassfish but also reveals potential clues regarding the historic productivity and regional oceanographic conditions of the Western Pacific marginal seas.

  6. Demographic response of cutlassfish (Trichiurus japonicus and T. nanhaiensis) to fluctuating palaeo-climate and regional oceanographic conditions in the China seas

    PubMed Central

    He, Lijun; Zhang, Aibing; Weese, David; Li, Shengfa; Li, Jiansheng; Zhang, Jing

    2014-01-01

    Glacial cycles of the Quaternary have heavily influenced the demographic history of various species. To test the evolutionary impact of palaeo-geologic and climatic events on the demographic history of marine taxa from the coastal Western Pacific, we investigated the population structure and demographic history of two economically important fish (Trichiurus japonicus and T. nanhaiensis) that inhabit the continental shelves of the East China and northern South China Seas using the mitochondrial cytochrome b sequences and Bayesian Skyline Plot analyses. A molecular rate of 2.03% per million years, calibrated to the earliest flooding of the East China Sea shelf (70–140 kya), revealed a strong correlation between population sizes and primary production. Furthermore, comparison of the demographic history of T. japonicus populations from the East China and South China Seas provided evidence of the postglacial development of the Changjiang (Yangtze River) Delta. In the South China Sea, interspecific comparisons between T. japonicus and T. nanhaiensis indicated possible evolutionary responses to changes in palaeo-productivity that were influenced by East Asian winter monsoons. This study not only provides insight into the demographic history of cutlassfish but also reveals potential clues regarding the historic productivity and regional oceanographic conditions of the Western Pacific marginal seas. PMID:25223336

  7. Demographic response of cutlassfish (Trichiurus japonicus and T. nanhaiensis) to fluctuating palaeo-climate and regional oceanographic conditions in the China seas.

    PubMed

    He, Lijun; Zhang, Aibing; Weese, David; Li, Shengfa; Li, Jiansheng; Zhang, Jing

    2014-01-01

    Glacial cycles of the Quaternary have heavily influenced the demographic history of various species. To test the evolutionary impact of palaeo-geologic and climatic events on the demographic history of marine taxa from the coastal Western Pacific, we investigated the population structure and demographic history of two economically important fish (Trichiurus japonicus and T. nanhaiensis) that inhabit the continental shelves of the East China and northern South China Seas using the mitochondrial cytochrome b sequences and Bayesian Skyline Plot analyses. A molecular rate of 2.03% per million years, calibrated to the earliest flooding of the East China Sea shelf (70-140 kya), revealed a strong correlation between population sizes and primary production. Furthermore, comparison of the demographic history of T. japonicus populations from the East China and South China Seas provided evidence of the postglacial development of the Changjiang (Yangtze River) Delta. In the South China Sea, interspecific comparisons between T. japonicus and T. nanhaiensis indicated possible evolutionary responses to changes in palaeo-productivity that were influenced by East Asian winter monsoons. This study not only provides insight into the demographic history of cutlassfish but also reveals potential clues regarding the historic productivity and regional oceanographic conditions of the Western Pacific marginal seas.

  8. Strategies for joint appointments.

    PubMed

    Royle, J; Crooks, D L

    1985-01-01

    The structure and policies governing joint appointments discussed above, are developed primarily through cooperation and collaboration between nursing service and education institutions. The joint appointee participates in the process of negotiation of salary, benefits and role responsibilities and exploration of the implications of the appointment for personal career development. Implementation and maintenance of the appointment requires the collaborative efforts of the joint appointee with both contracting agencies. Factors influencing the functioning of joint appointees have been identified and strategies to facilitate functioning presented. The joint appointee must be independent in thought and action yet adaptable to work within the boundaries of two social systems with differing values and expectations. Nursing management, peers and students can provide the support needed to overcome the frustrations and to achieve the rewards inherent in successful implementation of an exciting and innovative role. PMID:3852805

  9. Independent Demographic Responses to Climate Change among Temperate and Tropical Milksnakes (Colubridae: Genus Lampropeltis)

    PubMed Central

    Ruane, Sara; Torres-Carvajal, Omar; Burbrink, Frank T.

    2015-01-01

    The effects of Late Quaternary climate change have been examined for many temperate New World taxa, but the impact of Pleistocene glacial cycles on Neotropical taxa is less well understood, specifically with respect to changes in population demography. Here, we examine historical demographic trends for six species of milksnake with representatives in both the temperate and tropical Americas to determine if species share responses to climate change as a taxon or by area (i.e., temperate versus tropical environments). Using a multilocus dataset, we test for the demographic signature of population expansion and decline using non-genealogical summary statistics, as well as coalescent-based methods. In addition, we determine whether range sizes are correlated with effective population sizes for milksnakes. Results indicate that there are no identifiable trends with respect to demographic response based on location, and that species responded to changing climates independently, with tropical taxa showing greater instability. There is also no correlation between range size and effective population size, with the largest population size belonging to the species with the smallest geographic distribution. Our study highlights the importance of not generalizing the demographic histories of taxa by region and further illustrates that the New World tropics may not have been a stable refuge during the Pleistocene. PMID:26083467

  10. Demographics: Diversity in More Forms. Student Demographics, Now and the Future.

    ERIC Educational Resources Information Center

    Windham, Patricia; And Others

    While demographic diversity among the student body has increased substantially over the past several decades, the academic, economic, and social diversity of students will play a greater part in upcoming staffing and faculty requirements at community colleges. Data from Tallahassee Community College (TCC), in Florida, from 1980 to 1994 indicate…

  11. Temperomandibular joint ankylosis in children

    PubMed Central

    Jayavelu, Perumal; Shrutha, S. P.; Vinit, G. B.

    2014-01-01

    Temperomandibular joint (TMJ) ankylosis or hypo mobility involves fusion of the mandibular condyle to the base of the skull. Impairment of speech, difficulty in mastication, poor oral hygiene, rampant caries, and acute compromise of the airway pose a severe psychological burden on the tender minds of children. The treatment of TMJ ankylosis poses a significant challenge because of technical difficulties and a high incidence of recurrence. This report describes a case of 7-year-old with inability to open mouth, diagnosed with unilateral right bony TMJ ankylosis. The surgical approach consisted of inter-positional arthroplasty followed by physiotherapy. A detailed history, clinical and functional examination, and radiographic examination facilitating correct diagnosis followed by immediate surgical intervention and physiotherapy can help us to restore physical, psychological and emotional health of the child patient. PMID:25210367

  12. Demographic evidence of illegal harvesting of an endangered asian turtle.

    PubMed

    Sung, Yik-Hei; Karraker, Nancy E; Hau, Billy C H

    2013-12-01

    Harvesting pressure on Asian freshwater turtles is severe, and dramatic population declines of these turtles are being driven by unsustainable collection for food markets, pet trade, and traditional Chinese medicine. Populations of big-headed turtle (Platysternon megacephalum) have declined substantially across its distribution, particularly in China, because of overcollection. To understand the effects of chronic harvesting pressure on big-headed turtle populations, we examined the effects of illegal harvesting on the demography of populations in Hong Kong, where some populations still exist. We used mark-recapture methods to compare demographic characteristics between sites with harvesting histories and one site in a fully protected area. Sites with a history of illegal turtle harvesting were characterized by the absence of large adults and skewed ratios of juveniles to adults, which may have negative implications for the long-term viability of populations. These sites also had lower densities of adults and smaller adult body sizes than the protected site. Given that populations throughout most of the species' range are heavily harvested and individuals are increasingly difficult to find in mainland China, the illegal collection of turtles from populations in Hong Kong may increase over time. Long-term monitoring of populations is essential to track effects of illegal collection, and increased patrolling is needed to help control illegal harvesting of populations, particularly in national parks. Because few, if any, other completely protected populations remain in the region, our data on an unharvested population of big-headed turtles serve as an important reference for assessing the negative consequences of harvesting on populations of stream turtles. Evidencia Demográfica de la Captura Ilegal de una Tortuga Asiática en Peligro.

  13. Genetic Stratigraphy of Key Demographic Events in Arabia

    PubMed Central

    Fernandes, Verónica; Triska, Petr; Pereira, Joana B.; Alshamali, Farida; Rito, Teresa; Machado, Alison; Fajkošová, Zuzana; Cavadas, Bruno; Černý, Viktor; Soares, Pedro

    2015-01-01

    At the crossroads between Africa and Eurasia, Arabia is necessarily a melting pot, its peoples enriched by successive gene flow over the generations. Estimating the timing and impact of these multiple migrations are important steps in reconstructing the key demographic events in the human history. However, current methods based on genome-wide information identify admixture events inefficiently, tending to estimate only the more recent ages, as here in the case of admixture events across the Red Sea (∼8–37 generations for African input into Arabia, and 30–90 generations for “back-to-Africa” migrations). An mtDNA-based founder analysis, corroborated by detailed analysis of the whole-mtDNA genome, affords an alternative means by which to identify, date and quantify multiple migration events at greater time depths, across the full range of modern human history, albeit for the maternal line of descent only. In Arabia, this approach enables us to infer several major pulses of dispersal between the Near East and Arabia, most likely via the Gulf corridor. Although some relict lineages survive in Arabia from the time of the out-of-Africa dispersal, 60 ka, the major episodes in the peopling of the Peninsula took place from north to south in the Late Glacial and, to a lesser extent, the immediate post-glacial/Neolithic. Exchanges across the Red Sea were mainly due to the Arab slave trade and maritime dominance (from ∼2.5 ka to very recent times), but had already begun by the early Holocene, fuelled by the establishment of maritime networks since ∼8 ka. The main “back-to-Africa” migrations, again undetected by genome-wide dating analyses, occurred in the Late Glacial period for introductions into eastern Africa, whilst the Neolithic was more significant for migrations towards North Africa. PMID:25738654

  14. Climatic influence on demographic parameters of a tropical seabird varies with age and sex.

    PubMed

    Oro, Daniel; Torres, Roxana; Rodríguez, Cristina; Drummond, Hugh

    2010-04-01

    In marine ecosystems climatic fluctuation and other physical variables greatly influence population dynamics, but differential effects of physical variables on the demographic parameters of the two sexes and different age classes are largely unexplored. We analyzed the effects of climate on the survival and recruitment of both sexes and several age classes of a long-lived tropical seabird, the Blue-footed Booby (Sula nebouxii), using long-term observations on marked individuals. Results demonstrated a complex interaction between yearly fluctuations in climate (both local and global indexes, during both winter and breeding season) and the sex and age of individuals. Youngest birds' survival and recruitment were commonly affected by local climate, whereas oldest birds' parameters tended to be constant and less influenced by environmental variables. These results confirm the theoretical prediction that sex- and age-related variation in life-history demographic traits is greater under poor environmental conditions, and they highlight the importance of including variability in fitness components in demographic and evolutionary models. Males and females showed similar variation in survival but different recruitment patterns, in relation to both age and the spatial scale of climatic influence (local or global). Results indicate different life-history tactics for each sex and different ages, with birds likely trying to maximize their fitness by responding to the environmental contingencies of each year.

  15. Climatic influence on demographic parameters of a tropical seabird varies with age and sex.

    PubMed

    Oro, Daniel; Torres, Roxana; Rodríguez, Cristina; Drummond, Hugh

    2010-04-01

    In marine ecosystems climatic fluctuation and other physical variables greatly influence population dynamics, but differential effects of physical variables on the demographic parameters of the two sexes and different age classes are largely unexplored. We analyzed the effects of climate on the survival and recruitment of both sexes and several age classes of a long-lived tropical seabird, the Blue-footed Booby (Sula nebouxii), using long-term observations on marked individuals. Results demonstrated a complex interaction between yearly fluctuations in climate (both local and global indexes, during both winter and breeding season) and the sex and age of individuals. Youngest birds' survival and recruitment were commonly affected by local climate, whereas oldest birds' parameters tended to be constant and less influenced by environmental variables. These results confirm the theoretical prediction that sex- and age-related variation in life-history demographic traits is greater under poor environmental conditions, and they highlight the importance of including variability in fitness components in demographic and evolutionary models. Males and females showed similar variation in survival but different recruitment patterns, in relation to both age and the spatial scale of climatic influence (local or global). Results indicate different life-history tactics for each sex and different ages, with birds likely trying to maximize their fitness by responding to the environmental contingencies of each year. PMID:20462134

  16. [Demographic analysis of the blue shark, Prionace glauca, in the North Atlantic Ocean].

    PubMed

    Gao, Chun-xia; Dai, Xiao-jie; Tian, Si-quan; Wu, Feng; Zhu, Jiang-feng

    2016-02-01

    The blue shark, Prionace glauca, is the main by-catch species in tuna longline fishery. As one of top species in the oceanic food webs, the blue shark plays an important role in the marine ecosystem. Traditional stock assessment methods are difficult to accurately evaluate the population dynamic for this shark because of limited data. Based on life-history parameters of the blue shark in the North Atlantic, demographic analysis was employed to estimate the demographic parameters and evaluate the potential exploitation for the blue shark. Moreover, we discussed the relationship between age at first capture and critical value of fishing mortality corresponding to the value of intrinsic rate of natural increase 0. The results showed that the survival rate (S) of blue shark from 0.719 to 0.820, intrinsic rate of natural increase (r0) from 0.250 to 0.381, time of population doubling (tx2) from 1.819 to 2.773 years, reproduction rate per generation (R0) from 6.600 to 22.255, and generation time (G) from 8.498 to 10.162 years. The sensitivity analysis for the life history parameters revealed that the uncertainties of natural mortality existed in the first age class, age at maturity and maximum age had slight influence on the demographic parameters. Fishing mortality (Fc) increased with the age at first capture. When the age at first capture (tc) was more than five, there was no obvious relationship between Fc and tc.

  17. How well can body size represent effects of the environment on demographic rates? Disentangling correlated explanatory variables.

    PubMed

    Brooks, Mollie E; Mugabo, Marianne; Rodgers, Gwendolen M; Benton, Timothy G; Ozgul, Arpat

    2016-03-01

    Demographic rates are shaped by the interaction of past and current environments that individuals in a population experience. Past environments shape individual states via selection and plasticity, and fitness-related traits (e.g. individual size) are commonly used in demographic analyses to represent the effect of past environments on demographic rates. We quantified how well the size of individuals captures the effects of a population's past and current environments on demographic rates in a well-studied experimental system of soil mites. We decomposed these interrelated sources of variation with a novel method of multiple regression that is useful for understanding nonlinear relationships between responses and multicollinear explanatory variables. We graphically present the results using area-proportional Venn diagrams. Our novel method was developed by combining existing methods and expanding upon them. We showed that the strength of size as a proxy for the past environment varied widely among vital rates. For instance, in this organism with an income breeding life history, the environment had more effect on reproduction than individual size, but with substantial overlap indicating that size encompassed some of the effects of the past environment on fecundity. This demonstrates that the strength of size as a proxy for the past environment can vary widely among life-history processes within a species, and this variation should be taken into consideration in trait-based demographic or individual-based approaches that focus on phenotypic traits as state variables. Furthermore, the strength of a proxy will depend on what state variable(s) and what demographic rate is being examined; that is, different measures of body size (e.g. length, volume, mass, fat stores) will be better or worse proxies for various life-history processes.

  18. Demographic factors and playing variables in online computer gaming.

    PubMed

    Griffiths, Mark D; Davies, Mark N O; Chappell, Darren

    2004-08-01

    Despite the growing popularity of online game playing, there has been no primary survey of its players. Therefore, an online questionnaire survey was used to examine basic demographic factors of online computer game players who played the popular online game Everquest (i.e., gender, age, marital status, nationality, education level, occupation). The survey also examined playing frequency (i.e., amount of time spent playing the game a week), playing history (i.e., how long they had been playing the game, who they played the game with, whether they had ever gender swapped their game character), the favorite and least favorite aspects of playing the game, and what they sacrifice (if anything) to play the game. Results showed that 81% of online game players were male, and that the mean age of players was 27.9 years of age. For many players, the social aspects of the game were the most important factor in playing. A small minority of players appear to play excessively (over 80 h a week), and results suggest that a small minority sacrifice important activities in order to play (e.g., sleep, time with family and/or partner, work, or schooling). PMID:15331036

  19. Demographic factors and playing variables in online computer gaming.

    PubMed

    Griffiths, Mark D; Davies, Mark N O; Chappell, Darren

    2004-08-01

    Despite the growing popularity of online game playing, there has been no primary survey of its players. Therefore, an online questionnaire survey was used to examine basic demographic factors of online computer game players who played the popular online game Everquest (i.e., gender, age, marital status, nationality, education level, occupation). The survey also examined playing frequency (i.e., amount of time spent playing the game a week), playing history (i.e., how long they had been playing the game, who they played the game with, whether they had ever gender swapped their game character), the favorite and least favorite aspects of playing the game, and what they sacrifice (if anything) to play the game. Results showed that 81% of online game players were male, and that the mean age of players was 27.9 years of age. For many players, the social aspects of the game were the most important factor in playing. A small minority of players appear to play excessively (over 80 h a week), and results suggest that a small minority sacrifice important activities in order to play (e.g., sleep, time with family and/or partner, work, or schooling).

  20. MISR JOINT_AS Data

    Atmospheric Science Data Center

    2014-07-21

    Joint Aerosol Product (JOINT_AS) The MISR Level 3 Products are global or regional ... field campaigns at daily and monthly time scales. The Joint Aerosol product provides a monthly global statistical summary of MISR ...

  1. Handbook on dynamics of jointed structures.

    SciTech Connect

    Ames, Nicoli M.; Lauffer, James P.; Jew, Michael D.; Segalman, Daniel Joseph; Gregory, Danny Lynn; Starr, Michael James; Resor, Brian Ray

    2009-07-01

    The problem of understanding and modeling the complicated physics underlying the action and response of the interfaces in typical structures under dynamic loading conditions has occupied researchers for many decades. This handbook presents an integrated approach to the goal of dynamic modeling of typical jointed structures, beginning with a mathematical assessment of experimental or simulation data, development of constitutive models to account for load histories to deformation, establishment of kinematic models coupling to the continuum models, and application of finite element analysis leading to dynamic structural simulation. In addition, formulations are discussed to mitigate the very short simulation time steps that appear to be required in numerical simulation for problems such as this. This handbook satisfies the commitment to DOE that Sandia will develop the technical content and write a Joints Handbook. The content will include: (1) Methods for characterizing the nonlinear stiffness and energy dissipation for typical joints used in mechanical systems and components. (2) The methodology will include practical guidance on experiments, and reduced order models that can be used to characterize joint behavior. (3) Examples for typical bolted and screw joints will be provided.

  2. Pressure vessel flex joint

    NASA Technical Reports Server (NTRS)

    Kahn, Jon B. (Inventor)

    1992-01-01

    An airtight, flexible joint is disclosed for the interfacing of two pressure vessels such as between the Space Station docking tunnel and the Space Shuttle Orbiter bulkhead adapter. The joint provides for flexibility while still retaining a structural link between the two vessels required due to the loading created by the internal/external pressure differential. The joint design provides for limiting the axial load carried across the joint to a specific value, a function returned in the Orbiter/Station tunnel interface. The flex joint comprises a floating structural segment which is permanently attached to one of the pressure vessels through the use of an inflatable seal. The geometric configuration of the joint causes the tension between the vessels created by the internal gas pressure to compress the inflatable seal. The inflation pressure of the seal is kept at a value above the internal/external pressure differential of the vessels in order to maintain a controlled distance between the floating segment and pressure vessel. The inflatable seal consists of either a hollow torus-shaped flexible bladder or two rolling convoluted diaphragm seals which may be reinforced by a system of straps or fabric anchored to the hard structures. The joint acts as a flexible link to allow both angular motion and lateral displacement while it still contains the internal pressure and holds the axial tension between the vessels.

  3. Uncovering History for Future History Teachers

    ERIC Educational Resources Information Center

    Fischer, Fritz

    2010-01-01

    The art of history teaching is at a crossroads. Recent scholarship focuses on the need to change the teaching of history so students can better learn history, and insists that history teachers must move beyond traditional structures and methods of teaching in order to improve their students' abilities to think with history. This article presents…

  4. Demographic group differences in adolescents' time attitudes.

    PubMed

    Andretta, James R; Worrell, Frank C; Mello, Zena R; Dixson, Dante D; Baik, Sharon H

    2013-04-01

    In the present study, we examined demographic differences in time attitudes in a sample of 293 adolescents. Time attitudes were measured using the Adolescent Time Attitude Scale (Mello & Worrell, 2007; Worrell, Mello, & Buhl, 2011), which assesses positive and negative attitudes toward the past, the present, and the future. Generally, African Americans and Asian Americans reported higher scores for negative time attitudes and lower scores for positive time attitudes than European Americans and Latinos, with medium sizes. Adolescents in the low socioeconomic status group reported a less favorable evaluation of their past than middle and high SES peers, but there were no meaningful differences in time attitudes by gender. Findings indicate that middle SES adolescents, high school juniors and seniors, Latinos, and European Americans had higher representation in positive time attitude clusters (i.e., Positives and Balanced) than high SES adolescents, high school freshmen and sophomores, and African Americans.

  5. Fire victims: medical outcomes and demographic characteristics.

    PubMed Central

    Levine, M S; Radford, E P

    1977-01-01

    The medical outcomes and demographic characteristics of all victims of fires identified by The Baltimore Fire Department during a 14-month period in Baltimore City were studied. Fifty-nine per cent of victims suffered minor injuries, 25 per cent required hospitalization and 16 per cent were fatalities. The majority of survivable injuries were due to burns, while the majority of deaths were due to pulmonary injury and carbon monoxide intoxication. Deaths occurring at the scene of the fire or during the first 24 hours were predominantly due to carbon monoxide. Exposure to fires was more likely to result in deaths in the very young and very old. Evidence from autopsy protocols suggests that alcohol was a contributory factor. PMID:911020

  6. The Demographics of Women in Astronomy

    NASA Astrophysics Data System (ADS)

    Urry, M.; Marvel, K. B.; Blacker, B.

    1999-12-01

    To assess the status of women in astronomy we need data. How many women are astronomers? How does this percentage change with professional level? Do women have an advantage over men in hiring or other professional opportunities, or do men have the advantage, or is the playing field level? Using recent STScI and AAS surveys, I report the gender demographics in U.S. astronomy departments in 1999. Roughly 1/4 of astronomy graduate students are women, and this percentage decreases with rank, to 6% at the full professor level. Comparing to similar data from 1992, it appears that women fall behind men at the first transition, from graduate student to postdoc, but then keep pace with men in moving to faculty positions. (There is no sign that women advance more easily than men.) Interestingly, the percentage of women is slighly higher in the larger, better known institutions than in the profession as a whole.

  7. 3D face analysis for demographic biometrics

    SciTech Connect

    Tokola, Ryan A; Mikkilineni, Aravind K; Boehnen, Chris Bensing

    2015-01-01

    Despite being increasingly easy to acquire, 3D data is rarely used for face-based biometrics applications beyond identification. Recent work in image-based demographic biometrics has enjoyed much success, but these approaches suffer from the well-known limitations of 2D representations, particularly variations in illumination, texture, and pose, as well as a fundamental inability to describe 3D shape. This paper shows that simple 3D shape features in a face-based coordinate system are capable of representing many biometric attributes without problem-specific models or specialized domain knowledge. The same feature vector achieves impressive results for problems as diverse as age estimation, gender classification, and race classification.

  8. Compliant Joints For Robots

    NASA Technical Reports Server (NTRS)

    Kerley, James J., Jr.

    1990-01-01

    Compliant joints devised to accommodate misalignments of tools and/or workpieces with respect to robotic manipulators. Has characteristics and appearance of both universal-joint and cable-spring-type flexible shaft coupling. Compliance derived from elastic properties of short pieces of cable. Compliance of joint determined by lengths, distances between, relative orientations, thickness of strands, number of strands, material, amount of pretwist, and number of short pieces of cable. Worm-drive mechanism used to adjust lengths to vary compliance as needed during operation.

  9. Total ankle joint replacement.

    PubMed

    2016-02-01

    Ankle arthritis results in a stiff and painful ankle and can be a major cause of disability. For people with end-stage ankle arthritis, arthrodesis (ankle fusion) is effective at reducing pain in the shorter term, but results in a fixed joint, and over time the loss of mobility places stress on other joints in the foot that may lead to arthritis, pain and dysfunction. Another option is to perform a total ankle joint replacement, with the aim of giving the patient a mobile and pain-free ankle. In this article we review the efficacy of this procedure, including how it compares to ankle arthrodesis, and consider the indications and complications.

  10. Naturally rare versus newly rare: demographic inferences on two timescales inform conservation of Galápagos giant tortoises.

    PubMed

    Garrick, Ryan C; Kajdacsi, Brittney; Russello, Michael A; Benavides, Edgar; Hyseni, Chaz; Gibbs, James P; Tapia, Washington; Caccone, Adalgisa

    2015-02-01

    Long-term population history can influence the genetic effects of recent bottlenecks. Therefore, for threatened or endangered species, an understanding of the past is relevant when formulating conservation strategies. Levels of variation at neutral markers have been useful for estimating local effective population sizes (N e ) and inferring whether population sizes increased or decreased over time. Furthermore, analyses of genotypic, allelic frequency, and phylogenetic information can potentially be used to separate historical from recent demographic changes. For 15 populations of Galápagos giant tortoises (Chelonoidis sp.), we used 12 microsatellite loci and DNA sequences from the mitochondrial control region and a nuclear intron, to reconstruct demographic history on shallow (past ∽100 generations, ∽2500 years) and deep (pre-Holocene, >10 thousand years ago) timescales. At the deep timescale, three populations showed strong signals of growth, but with different magnitudes and timing, indicating different underlying causes. Furthermore, estimated historical N e of populations across the archipelago showed no correlation with island age or size, underscoring the complexity of predicting demographic history a priori. At the shallow timescale, all populations carried some signature of a genetic bottleneck, and for 12 populations, point estimates of contemporary N e were very small (i.e., < 50). On the basis of the comparison of these genetic estimates with published census size data, N e generally represented ∽0.16 of the census size. However, the variance in this ratio across populations was considerable. Overall, our data suggest that idiosyncratic and geographically localized forces shaped the demographic history of tortoise populations. Furthermore, from a conservation perspective, the separation of demographic events occurring on shallow versus deep timescales permits the identification of naturally rare versus newly rare populations; this distinction

  11. Naturally rare versus newly rare: demographic inferences on two timescales inform conservation of Galápagos giant tortoises

    PubMed Central

    Garrick, Ryan C; Kajdacsi, Brittney; Russello, Michael A; Benavides, Edgar; Hyseni, Chaz; Gibbs, James P; Tapia, Washington; Caccone, Adalgisa

    2015-01-01

    Long-term population history can influence the genetic effects of recent bottlenecks. Therefore, for threatened or endangered species, an understanding of the past is relevant when formulating conservation strategies. Levels of variation at neutral markers have been useful for estimating local effective population sizes (Ne) and inferring whether population sizes increased or decreased over time. Furthermore, analyses of genotypic, allelic frequency, and phylogenetic information can potentially be used to separate historical from recent demographic changes. For 15 populations of Galápagos giant tortoises (Chelonoidis sp.), we used 12 microsatellite loci and DNA sequences from the mitochondrial control region and a nuclear intron, to reconstruct demographic history on shallow (past ∽100 generations, ∽2500 years) and deep (pre-Holocene, >10 thousand years ago) timescales. At the deep timescale, three populations showed strong signals of growth, but with different magnitudes and timing, indicating different underlying causes. Furthermore, estimated historical Ne of populations across the archipelago showed no correlation with island age or size, underscoring the complexity of predicting demographic history a priori. At the shallow timescale, all populations carried some signature of a genetic bottleneck, and for 12 populations, point estimates of contemporary Ne were very small (i.e., < 50). On the basis of the comparison of these genetic estimates with published census size data, Ne generally represented ∽0.16 of the census size. However, the variance in this ratio across populations was considerable. Overall, our data suggest that idiosyncratic and geographically localized forces shaped the demographic history of tortoise populations. Furthermore, from a conservation perspective, the separation of demographic events occurring on shallow versus deep timescales permits the identification of naturally rare versus newly rare populations; this distinction should

  12. Demographic change and marriage choices in one Carib family.

    PubMed

    Adams, K

    1994-03-01

    The demographic adaptation of a family of Topside Caribs along the Barama River in Guyana was studied. The family history included two grandfather and granddaughter marriages. Jack Raymond's father, who was born in 1870, left Bottomside after the death of his wife in the 1920s and settled above the falls of the Barama River (Topside in Sawari) with the hope of subsistence living off the rain forest. Information on the grandfather generation was made difficult by name changes, general references to all men in the second generation as grandfathers, and the focus on father's and mother's generation. The typical pattern was for brothers to live close by, and intermarry with a family of sisters. Female children married mother's brothers' sons or father's sisters sons. Their children formed their own cluster settlements. The early history indicated economic hardship, loss of wives, and difficulties in remarrying. The Baird chronicles of the reintroduction of gold mining and the ethnography of Gillin indicated that malaria and round worm were diseases affecting the indigenous population during the 1920s and 1930s. The Topside population was supported by the local gold-mining economy, while the Bottomside population suffered economic hardship and high infant mortality. In the Jack Raymond family, remarriage resulted in children marrying cross cousins. The younger daughter married in the 1940s, when subsistence production of cassava and hunting and gold-mining income provided the family's livelihood. The daughter had 10 surviving children, compared to her adoptive mother's two. For the daughter's generation, the first pregnancy occurred between the ages of 18 and 22 years, and birth spacing was 20-30 months for 25 years. Neither polygyny nor monogamy affected the potential for 12 children. In this Baramita Air Strip population in 1971, there were 62 mothers; reproductive histories were available for 59. The changes in reproductive patterns after 1940 were apparent: for

  13. Knee joint replacement

    MedlinePlus

    ... is used to attach this part. Repair your muscles and tendons around the new joint and close the surgical cut. The surgery takes about 2 hours. Most artificial knees have both metal and plastic parts. Some ...

  14. Wrist joint assembly

    NASA Technical Reports Server (NTRS)

    Kersten, L.; Johnson, J. D. (Inventor)

    1978-01-01

    A wrist joint assembly is provided for use with a mechanical manipulator arm for finely positioning an end-effector carried by the wrist joint on the terminal end of the manipulator arm. The wrist joint assembly is pivotable about a first axis to produce a yaw motion, a second axis is to produce a pitch motion, and a third axis to produce a roll motion. The wrist joint assembly includes a disk segment affixed to the terminal end of the manipulator arm and a first housing member, a second housing member, and a third housing member. The third housing member and the mechanical end-effector are moved in the yaw, pitch, and roll motion. Drive means are provided for rotating each of the housings about their respective axis which includes a cluster of miniature motors having spur gears carried on the output drive shaft which mesh with a center drive gear affixed on the housing to be rotated.

  15. Improved orthopedic arm joint

    NASA Technical Reports Server (NTRS)

    Dane, D. H.

    1971-01-01

    Joint permits smooth and easy movement of disabled arm and is smaller, lighter and less expensive than previous models. Device is interchangeable and may be used on either arm at the shoulder or at the elbow.

  16. Joint fluid Gram stain

    MedlinePlus

    Gram stain of joint fluid ... result means no bacteria are present on the Gram stain. Normal value ranges may vary slightly among ... Abnormal results mean bacteria were seen on the Gram stain. This may be a sign of a ...

  17. Scaling in Columnar Joints

    NASA Astrophysics Data System (ADS)

    Morris, Stephen

    2007-03-01

    Columnar jointing is a fracture pattern common in igneous rocks in which cracks self-organize into a roughly hexagonal arrangement, leaving behind an ordered colonnade. We report observations of columnar jointing in a laboratory analog system, desiccated corn starch slurries. Using measurements of moisture density, evaporation rates, and fracture advance rates, we suggest an advective-diffusive system is responsible for the rough scaling behavior of columnar joints. This theory explains the order of magnitude difference in scales between jointing in lavas and in starches. We investigated the scaling of average columnar cross-sectional areas in experiments where the evaporation rate was fixed using feedback methods. Our results suggest that the column area at a particular depth is related to both the current conditions, and hysteretically to the geometry of the pattern at previous depths. We argue that there exists a range of stable column scales allowed for any particular evaporation rate.

  18. Hip joint injection

    MedlinePlus

    ... injected so the provider can see where to place the medicine. The steroid medicine is slowly injected into the joint. After the injection, you will remain on the table for another 5 to 10 minutes or so. ...

  19. Temporomandibular Joint Disorder

    MedlinePlus

    ... 2008 Previous Next Related Articles: Temporomandibular Joint Disorder (TMD) Are You Biting Off More Than You Can Chew? Equilibration May Lessen TMD Pain Fender-benders: Source of TMD? First Comes ...

  20. Panel Post & Diagonal Brace Joint Detail; Crossbracing Center Joint ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Panel Post & Diagonal Brace Joint Detail; Crossbracing Center Joint Detail; Chord, Panel Post, Tie Bar, & Diagonal Brace Joint Detail; Chord, Tie Bar, & Crossbracing Joint Detail - Medora Bridge, Spanning East Fork of White River at State Route 235, Medora, Jackson County, IN

  1. Planning Marine Reserve Networks for Both Feature Representation and Demographic Persistence Using Connectivity Patterns

    PubMed Central

    Bode, Michael; Williamson, David H.; Weeks, Rebecca; Jones, Geoff P.; Almany, Glenn R.; Harrison, Hugo B.; Hopf, Jess K.; Pressey, Robert L.

    2016-01-01

    Marine reserve networks must ensure the representation of important conservation features, and also guarantee the persistence of key populations. For many species, designing reserve networks is complicated by the absence or limited availability of spatial and life-history data. This is particularly true for data on larval dispersal, which has only recently become available. However, systematic conservation planning methods currently incorporate demographic processes through unsatisfactory surrogates. There are therefore two key challenges to designing marine reserve networks that achieve feature representation and demographic persistence constraints. First, constructing a method that efficiently incorporates persistence as well as complementary feature representation. Second, incorporating persistence using a mechanistic description of population viability, rather than a proxy such as size or distance. Here we construct a novel systematic conservation planning method that addresses both challenges, and parameterise it to design a hypothetical marine reserve network for fringing coral reefs in the Keppel Islands, Great Barrier Reef, Australia. For this application, we describe how demographic persistence goals can be constructed for an important reef fish species in the region, the bar-cheeked trout (Plectropomus maculatus). We compare reserve networks that are optimally designed for either feature representation or demographic persistence, with a reserve network that achieves both goals simultaneously. As well as being practically applicable, our analyses also provide general insights into marine reserve planning for both representation and demographic persistence. First, persistence constraints for dispersive organisms are likely to be much harder to achieve than representation targets, due to their greater complexity. Second, persistence and representation constraints pull the reserve network design process in divergent directions, making it difficult to

  2. Planning Marine Reserve Networks for Both Feature Representation and Demographic Persistence Using Connectivity Patterns.

    PubMed

    Bode, Michael; Williamson, David H; Weeks, Rebecca; Jones, Geoff P; Almany, Glenn R; Harrison, Hugo B; Hopf, Jess K; Pressey, Robert L

    2016-01-01

    Marine reserve networks must ensure the representation of important conservation features, and also guarantee the persistence of key populations. For many species, designing reserve networks is complicated by the absence or limited availability of spatial and life-history data. This is particularly true for data on larval dispersal, which has only recently become available. However, systematic conservation planning methods currently incorporate demographic processes through unsatisfactory surrogates. There are therefore two key challenges to designing marine reserve networks that achieve feature representation and demographic persistence constraints. First, constructing a method that efficiently incorporates persistence as well as complementary feature representation. Second, incorporating persistence using a mechanistic description of population viability, rather than a proxy such as size or distance. Here we construct a novel systematic conservation planning method that addresses both challenges, and parameterise it to design a hypothetical marine reserve network for fringing coral reefs in the Keppel Islands, Great Barrier Reef, Australia. For this application, we describe how demographic persistence goals can be constructed for an important reef fish species in the region, the bar-cheeked trout (Plectropomus maculatus). We compare reserve networks that are optimally designed for either feature representation or demographic persistence, with a reserve network that achieves both goals simultaneously. As well as being practically applicable, our analyses also provide general insights into marine reserve planning for both representation and demographic persistence. First, persistence constraints for dispersive organisms are likely to be much harder to achieve than representation targets, due to their greater complexity. Second, persistence and representation constraints pull the reserve network design process in divergent directions, making it difficult to

  3. High pressure ceramic joint

    DOEpatents

    Ward, M.E.; Harkins, B.D.

    1993-11-30

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures. 4 figures.

  4. High pressure ceramic joint

    DOEpatents

    Ward, Michael E.; Harkins, Bruce D.

    1993-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  5. Cygnus History

    SciTech Connect

    David J. Henderson, Raymond E. Gignac, Douglas E. Good, Mark D. Hansen, Charles V. Mitton; Daniel S. Nelson, Eugene C. Ormond; Steve R. Cordova, Isidro Molina; John R. Smith, Evan A. Rose

    2009-07-02

    The Cygnus Dual Beam Radiographic Facility consists of two identical radiographic sources: Cygnus 1 and Cygnus 2. This Radiographic Facility is located in an underground tunnel test area at the Nevada Test Site. The sources were developed to produce high-resolution images for dynamic plutonium experiments. This work will recount and discuss salient maintenance and operational issues encountered during the history of Cygnus. A brief description of Cygnus systems and rational for design selections will set the stage for this historical narrative. It is intended to highlight the team-derived solutions for technical problems encountered during extended periods of maintenance and operation. While many of the issues are typical to pulsed power systems, some of the solutions are unique. It is hoped that other source teams will benefit from this presentation, as well as other necessary disciplines (e.g., source users, system architects, facility designers and managers, funding managers, and team leaders).

  6. Evaluating the importance of demographic connectivity in a marine metapopulation.

    PubMed

    Carson, Henry S; Cook, Geoffrey S; López-Duarte, Paola C; Levin, Lisa A

    2011-10-01

    Recently researchers have gone to great lengths to measure marine metapopulation connectivity via tagging, genetic, and trace-elemental fingerprinting studies. These empirical estimates of larval dispersal are key to assessing the significance of metapopulation connectivity within a demographic context, but the life-history data required to do this are rarely available. To evaluate the demographic consequences of connectivity we constructed seasonal, size-structured metapopulation matrix models for two species of mytilid mussel in San Diego County, California, USA. The self-recruitment and larval exchange terms were produced from a time series of realized connectivities derived from trace-elemental fingerprinting of larval shells during spring and fall from 2003 to 2008. Both species exhibited a strong seasonal pattern of southward movement of recruits in spring and northward movement in fall. Growth and mortality terms were estimated using mark-recapture data from representative sites for each species and subpopulation, and literature estimates of juvenile mortality. Fecundity terms were estimated using county-wide settlement data from 2006-2008; these data reveal peak reproduction and recruitment in fall for Mytilus californianus, and spring for M. galloprovincialis. Elasticity and life-stage simulation analyses were employed to identify the season- and subpopulation-specific vital rates and connectivity terms to which the metapopulation growth rate (lambda) was most sensitive. For both species, metapopulation growth was most sensitive to proportional changes in adult fecundity, survival and growth of juvenile stages, and population connectivity, in order of importance, but relatively insensitive to adult growth or survival. The metapopulation concept was deemed appropriate for both Mytilus species as exchange between the subpopulations was necessary for subpopulation persistence. However, highest metapopulation growth occurred in years when a greater proportion

  7. Turkey between two worlds: a demographic view.

    PubMed

    Gallagher, C F

    1982-01-01

    A demographic view of Turkey is presented in this discussion. Turkey provides another example of a country, ravaged by war losses between 1914-1922, which took 4 decades, from the mid1920s to the mid1960s, to move from a pronatalist policy to an understanding of the social, economic, and most recently the political dangers of rampant population growth. The 1st census, taken in Turkey in 1927, showed a population of 13,648,270 living in an area of 299,294 square miles, substantially equal to its present dimensions. In mid1977 the population surpassed 42 million, and it reached 45.6 million in mid1980 estimates. The population grew by only 5.4% in the 1940-1945 intercensal period. With the return to normalcy following the war, Turkey's high wartime death rate (almost 40/1000 between 1940 and 1945) declined rapidly and population growth began to accelerate. It was toward the end of the 1950s that concern began to be expressed about the rapid population growth the country was experiencing. The Ministry of Health and Social Affairs and the State Planning Organization began to study the implications of the increase for future social and economic development. This reconsideration of the previous pronatalist policy, which had forbidden the dissemination of birth control supplies or information, received a stimulus following the coup of 1960 that brought the military to power. Under military rule from May 1960 to November 1961 an antinatalist position emerged and was incorporated in the 1963-1967 5 year plan and later in the Population Planning Law, No. 557, enacted in 1965. Law 557 was permissive yet essentially neutral. It did not interfere with the private decisions of couples to plan family size but it offered them contraceptive supplies and information free or at low cost as well as education in population matters. Abortion was legalized if the mother's health were endangered, but it was not allowed otherwise. Sterilization was prohibited. The implementation of these

  8. Turkey between two worlds: a demographic view.

    PubMed

    Gallagher, C F

    1982-01-01

    A demographic view of Turkey is presented in this discussion. Turkey provides another example of a country, ravaged by war losses between 1914-1922, which took 4 decades, from the mid1920s to the mid1960s, to move from a pronatalist policy to an understanding of the social, economic, and most recently the political dangers of rampant population growth. The 1st census, taken in Turkey in 1927, showed a population of 13,648,270 living in an area of 299,294 square miles, substantially equal to its present dimensions. In mid1977 the population surpassed 42 million, and it reached 45.6 million in mid1980 estimates. The population grew by only 5.4% in the 1940-1945 intercensal period. With the return to normalcy following the war, Turkey's high wartime death rate (almost 40/1000 between 1940 and 1945) declined rapidly and population growth began to accelerate. It was toward the end of the 1950s that concern began to be expressed about the rapid population growth the country was experiencing. The Ministry of Health and Social Affairs and the State Planning Organization began to study the implications of the increase for future social and economic development. This reconsideration of the previous pronatalist policy, which had forbidden the dissemination of birth control supplies or information, received a stimulus following the coup of 1960 that brought the military to power. Under military rule from May 1960 to November 1961 an antinatalist position emerged and was incorporated in the 1963-1967 5 year plan and later in the Population Planning Law, No. 557, enacted in 1965. Law 557 was permissive yet essentially neutral. It did not interfere with the private decisions of couples to plan family size but it offered them contraceptive supplies and information free or at low cost as well as education in population matters. Abortion was legalized if the mother's health were endangered, but it was not allowed otherwise. Sterilization was prohibited. The implementation of these

  9. Background and History of the Joint Committee's Program Evaluation Standards

    ERIC Educational Resources Information Center

    Yarbrough, Donald B.; Shulha, Lyn M.; Caruthers, Flora

    2004-01-01

    It is generally thought that evaluation originated with the civil service exams that were administered in ancient China. However, modern evaluation and, of particular importance to this article, evaluation standards, originated in the United States. Why this occurred is part of a larger question about the development of social and educational…

  10. The Joint Confidence Level Paradox: A History of Denial

    NASA Technical Reports Server (NTRS)

    Butts, Glenn; Linton, Kent

    2009-01-01

    This paper is intended to provide a reliable methodology for those tasked with generating price tags on construction (C0F) and research and development (R&D) activities in the NASA performance world. This document consists of a collection of cost-related engineering detail and project fulfillment information from early agency days to the present. Accurate historical detail is the first place to start when determining improved methodologies for future cost and schedule estimating. This paper contains a beneficial proposed cost estimating method for arriving at more reliable numbers for future submits. When comparing current cost and schedule methods with earlier cost and schedule approaches, it became apparent that NASA's organizational performance paradigm has morphed. Mission fulfillment speed has slowed and cost calculating factors have increased in 21st Century space exploration.

  11. Demographic and childhood environmental predictors of resilience in a community sample.

    PubMed

    Campbell-Sills, Laura; Forde, David R; Stein, Murray B

    2009-08-01

    Scientific investigation of resilient responses to stress and trauma has the potential to inform models of the etiology, treatment, and prevention of stress-related psychiatric disorders (e.g. posttraumatic stress disorder). Despite building interest in and investigation of resilience, many basic questions regarding this construct remain unstudied. This study contributes to the empirical literature on resilience by providing novel information on the distribution and correlates of stress resilience in the general community. A well-validated self-report measure of resilience was completed by a large sample (N=764) of respondents to a telephone-based community survey that also included questions about demographics and history of childhood maltreatment. Multiple regression analyses showed that several demographic characteristics (sex, education level, and income level) uniquely predicted subjects' resilience to stress and that, taken together, these factors explained approximately 11% of the variance in resilience. Reported history of childhood maltreatment independently contributed to prediction of resilience and explained an additional 2% of the variance in this trait. While females, individuals with lower levels of education and income, and individuals with histories of childhood maltreatment reported diminished resilience overall, the majority of variance in the resilience measure was left unexplained leaving much room for other variables to influence a person's resilience to stress. Relationships of the present results to other research on resilient and pathological stress responses are discussed, as well as implications of these findings for future investigations of resilience.

  12. Population growth, demographic change, and cultural landscapes.

    PubMed

    Woodgate, G; Sage, C

    1994-01-01

    The inclusion of both ecological and socioeconomic components within landscapes makes possible the perception of the hierarchical character of landscape organization. A research approach is needed to conceptualize cultural landscapes as the product of interaction between society and nature. Richard Norgaard's 1984 paper on coevolutionary agricultural development attempts to meet this challenge. Coevolution is the interactive synthesis of natural and social mechanisms of change that characterize the relationship between social systems and ecosystems. The relationship between population, consumption, and environmental changes is complex. Currently industrialized countries present the biggest threat to global environmental resources. The issue of carrying capacity is the corollary of population and the environment. It is primarily the technological factor rather than population that needs to be controlled. The relationship between rich and poor countries is determined by superior economic power. An analysis of landscape change is made, tracing the coevolution of society and environment from the end of the feudal era and making comparisons with continental Europe. Over the years since 1945 the need to realize potential economies of scale has resulted in a wholesale loss of woodlands, hedgerows, and small ponds in the UK. In a global context the likely impacts of population growth and demographic change on landscapes will be influenced by such socioeconomic factors as technology and affluence; policies that ignore cause and effect; and the traditional tendency to treat the environment as a waste repository and a supply depot. PMID:12290867

  13. Developmental dyscalculia: prevalence and demographic features.

    PubMed

    Gross-Tsur, V; Manor, O; Shalev, R S

    1996-01-01

    One hundred and forty-three 11-year-old children with development dyscalculia, from a cohort of 3029 students, were studied to determine demographic features and prevalence of this primary cognitive disorder. They were evaluated for gender, IQ, linguistic and perceptual skills, symptoms of attention-deficit hyperactivity disorder (ADHD), socio-economic status and associated learned disabilities. The IQs of the 140 children (75 girls and 65 boys) retained in the study group (three were excluded because of low IQs) ranged from 80 to 129 (mean 98.2, SD 9.9). 26 per cent of the children had symptoms of ADHD, and 17 per cent had dyslexia. Their socio-economic status was significantly lower than that of the rest of the cohort, and 42 per cent had first-degree relatives with learning disabilities. The prevalence of dyscalculia in the original cohort was 6.5 per cent, similar to that of dyslexia and ADHD. However, unlike these other learning disabilities, dyscalculia affected the two sexes in about the same proportions. PMID:8606013

  14. Demographic impact of vaccination: a review.

    PubMed

    Bonanni, P

    1999-10-29

    Vaccination is one of the most powerful means to save lives and to increase the level of health of mankind. However, the impact of immunization against the most threatening infectious agents on life expectancy has been the object of a still open debate. The main issues are: the relative influence of nutrition and infectious diseases on demographic patterns of populations; the possibility that lives saved thanks to vaccination are subsequently lost due to other competing causes of death; the positive indirect effect of immunization on other causes of death. With regard to past evidence, several data from the United Kingdom and Scandinavian countries show that the widespread use of smallpox vaccination starting at the beginning of the nineteenth century resulted in a marked and sustained decline not only of smallpox-related deaths, but also of the overall crude death rate, and contributed greatly to an unprecedented growth of European population. As to the present, it is estimated that 3 million children are saved annually by vaccination, but 2 million still die because they are not immunized. Tetanus, measles and pertussis are the main vaccine-preventable killers in the first years of life. Data from Bangladesh show that full implementation of EPI vaccines has the potential of reducing mortality by almost one half in children aged 1-4 years. Recent progress in the development of vaccines against agents responsible for much mortality in the developing countries make it possible to forecast a further substantial reduction of deaths for infectious diseases in the next century.

  15. Emergence of Rapid Evolution from Demographic Stochasticity

    NASA Astrophysics Data System (ADS)

    Shih, Hong-Yan; Goldenfeld, Nigel

    2014-03-01

    The phenomenon of ``rapid evolution'' arises when genetic variation occurs fast enough to significantly change ecodynamics. Data from experiments with algae-rotifer system and bacteria-phage system show unusual dynamics when there are subpopulations of preys with different trait values, including predator-prey phase shifts near π (and distinct from the canonical value of π / 2) and so-called cryptic cycles, in which populations of preys remain constant while the predator population oscillates. Such phenomena have been modeled with deterministic differential equations containing empirical Michaelis-Menten kinetic terms and the unusual dynamics that is attributed to postulate complicated trade-off between sub-populations. Here we present a generic individual-level stochastic model of interacting populations that includes a subpopulation resistant to the predator but with metabolic cost. We solve this model by using a master equation approach, and by performing system size expansion, we find that antiphase and cryptic quasi-cycles can emerge from the combination of intrinsic demographic fluctuations and clonal mutations alone. These analytic results are then compared with Gillespie simulations, and the typical phase diagram of the system is calculated.

  16. Demographics of Resonances in Exoplanetary Systems

    NASA Astrophysics Data System (ADS)

    Ragozzine, Darin; Conaway, James L.; MacDonald, Mariah G.; Sallee, Victor

    2016-10-01

    NASA's Kepler Space Telescope has identified ~700 systems of multiple transiting exoplanets containing ~1700 planets. Most of these multi-transiting systems have 3-5 planets small planets with periods of roughly 5-50 days and are known as Systems with Tightly-spaced Inner Planets (STIPs). These information-rich exoplanetary systems have precisely measured period ratios which allows for the identification and characterization of orbital mean motion resonances. Improved understanding of the resonant populations will reveal much about the formation and evolution of planetary systems. Lissauer, Ragozzine, et al. 2011 found that most Kepler systems were not in resonance, but that there was a small excess of planets wide of resonance. We present new analyses that rigorously identify the frequency of planets in multiple resonances (including three-body resonances) and thus identify many specific new results on the demographics of resonances. We also show that the apparent over-abundance of resonances can be attributed to a difference in inclinations (potentially from dissipation) with implications for the true underlying frequency of resonant systems. We compare the period ratio distribution of Kepler (corrected for inclination biases) to Radial Velocity (RV) surveys and conclude that RV systems are often missing small intermediate planets. This has serious implications for the completeness of RV identification of planets in STIPs.

  17. Demographic controls of future global fire risk

    NASA Astrophysics Data System (ADS)

    Knorr, W.; Arneth, A.; Jiang, L.

    2016-08-01

    Wildfires are an important component of terrestrial ecosystem ecology but also a major natural hazard to societies, and their frequency and spatial distribution must be better understood. At a given location, risk from wildfire is associated with the annual fraction of burned area, which is expected to increase in response to climate warming. Until recently, however, only a few global studies of future fire have considered the effects of other important global environmental change factors such as atmospheric CO2 levels and human activities, and how these influence fires in different regions. Here, we contrast the impact of climate change and increasing atmospheric CO2 content on burned area with that of demographic dynamics, using ensembles of climate simulations combined with historical and projected population changes under different socio-economic development pathways for 1901-2100. Historically, humans notably suppressed wildfires. For future scenarios, global burned area will continue to decline under a moderate emissions scenario, except for low population growth and fast urbanization, but start to increase again from around mid-century under high greenhouse gas emissions. Contrary to common perception, we find that human exposure to wildfires increases in the future mainly owing to projected population growth in areas with frequent wildfires, rather than by a general increase in burned area.

  18. [Biomechanics of the ankle joint].

    PubMed

    Zwipp, H

    1989-03-01

    According to Fick, the tree-dimensional patterns of foot motion are best characterized as jawlike movement. Anatomically and biomechanically, this process represents conjoined, synchronous motion within the three mobile segments of the hindfoot: the ankle joint, the posterior subtalar joint, and the anterior subtalar joint. Foot kinematics can be described more completely if the anterior subtalar joint is defined not only as the talocalcaneal navicular joint, but as including the calcaneocuboid joint, thus representing the transverse joint of the tarsus, i.e., the Chopart joint. The axes of these three joints can be defined precisely. In some parts they represent a screwlike motion, clockwise or counter-clockwise, around the central ligamentous structures (fibulotibial ligament, talocalcaneal interosseous ligament, bifurcate ligament). The individual anatomy and structure of these ligaments provide variations in the degree and direction of foot motion. A precise knowledge of foot kinematics is important in surgical ligament and joint reconstruction and in selective foot arthrodeses.

  19. Teaching First Nations History as Canadian History.

    ERIC Educational Resources Information Center

    Reynolds, Graham

    2000-01-01

    Argues for the integration of aboriginal content into social studies by teaching First Nations history as Canadian history. Provides an overview of this integrated history, focusing on Atlantic Canada. Addresses such topics as extending the coverage 10,000 years prior, the parallel between human history and environmental change, and cultural…

  20. The Future of History and History Teaching.

    ERIC Educational Resources Information Center

    Commager, Henry Steele

    1983-01-01

    Technical history, a quantitative record of history strengthened by new techniques in mathematics, computer science, and other fields has advantages over former approaches to history--history as philosophy and historical theology. For example, it makes available more source materials. However, it has drawbacks, e.g., it directs research to highly…

  1. [Urbanization and its consequences for socio-demographic structures in Tunisia].

    PubMed

    Taamallah, M

    1986-01-01

    Comparisons are made between rural and urban populations in Tunisia in terms of selected demographic and social factors using official and other published data for the late 1970s and early 1980s. The focus is on the consequences of imbalances created by Tunisia's urbanization for population composition, health, economic development, and certain social structures. The history of urbanization in Tunisia since the end of the nineteenth century is outlined. Urban and rural populations are compared on the basis of sex distribution, age distribution, mortality, and fertility. The relationships among urbanization and economic development, public health, and family structure are considered. PMID:12314867

  2. Ras history

    PubMed Central

    2010-01-01

    Although the roots of Ras sprouted from the rich history of retrovirus research, it was the discovery of mutationally activated RAS genes in human cancer in 1982 that stimulated an intensive research effort to understand Ras protein structure, biochemistry and biology. While the ultimate goal has been developing anti-Ras drugs for cancer treatment, discoveries from Ras have laid the foundation for three broad areas of science. First, they focused studies on the origins of cancer to the molecular level, with the subsequent discovery of genes mutated in cancer that now number in the thousands. Second, elucidation of the biochemical mechanisms by which Ras facilitates signal transduction established many of our fundamental concepts of how a normal cell orchestrates responses to extracellular cues. Third, Ras proteins are also founding members of a large superfamily of small GTPases that regulate all key cellular processes and established the versatile role of small GTP-binding proteins in biology. We highlight some of the key findings of the last 28 years. PMID:21686117

  3. Joint ventures in medical services.

    PubMed

    Rublee, D A

    1987-01-01

    This paper is an overview of joint-venture activity in healthcare, describing trends in joint ventures and raising issues for physicians. The purposes are to discuss the major current facets of joint-venture alliances in healthcare and to identify policy issues that arise from the trend to use joint ventures as an organizational tool. Speculation is made about the future role of joint ventures in the organization of healthcare.

  4. History of Geology.

    ERIC Educational Resources Information Center

    Bork, Kennard B.

    1983-01-01

    Highlights geological history activities during 1982. These include formation of The History of Earth Sciences Societies, publication of a new journal ("Earth Sciences History: The Journal of the History of Earth Sciences Societies"), and presentation of the first history of geology award. Comments on geological history publications are also…

  5. Dissimilar metals joint evaluation

    NASA Technical Reports Server (NTRS)

    Wakefield, M. E.; Apodaca, L. E.

    1974-01-01

    Dissimilar metals tubular joints between 2219-T851 aluminum alloy and 304L stainless steel were fabricated and tested to evaluate bonding processes. Joints were fabricated by four processes: (1) inertia (friction) weldings, where the metals are spun and forced together to create the weld; (2) explosive welding, where the metals are impacted together at high velocity; (3) co-extrusion, where the metals are extruded in contact at high temperature to promote diffusion; and (4) swaging, where residual stresses in the metals after a stretching operation maintain forced contact in mutual shear areas. Fifteen joints of each type were prepared and evaluated in a 6.35 cm (2.50 in.) O.D. size, with 0.32 cm (0.13 in.) wall thickness, and 7.6 cm (3.0 in) total length. The joints were tested to evaluate their ability to withstand pressure cycle, thermal cycle, galvanic corrosion and burst tests. Leakage tests and other non-destructive test techniques were used to evaluate the behavior of the joints, and the microstructure of the bond areas was analyzed.

  6. Speciation and demographic history of Atlantic eels (Anguilla anguilla and A. rostrata) revealed by mitogenome sequencing.

    PubMed

    Jacobsen, M W; Pujolar, J M; Gilbert, M T P; Moreno-Mayar, J V; Bernatchez, L; Als, T D; Lobon-Cervia, J; Hansen, M M

    2014-11-01

    Processes leading to speciation in oceanic environments without obvious physical barriers remain poorly known. European and American eel (Anguilla anguilla and A. rostrata) spawn in partial sympatry in the Sargasso Sea. Larvae are advected by the Gulf Stream and other currents towards the European/North African and North American coasts, respectively. We analyzed 104 mitogenomes from the two species along with mitogenomes of other Anguilla and outgroup species. We estimated divergence time between the two species to identify major events involved in speciation. We also considered two previously stated hypotheses: one where the ancestral species was present in only one continent but was advected across the Atlantic by ocean current changes and another where population declines during Pleistocene glaciations led to increasing vicariance, facilitating speciation. Divergence time was estimated to ∼3.38 Mya, coinciding with the closure of the Panama Gateway that led to reinforcement of the Gulf Stream. This could have advected larvae towards European/North African coasts, in which case American eel would be expected to be the ancestral species. This scenario could, however, not be unequivocally confirmed by analyses of dN/dS, nucleotide diversity and effective population size estimates. Extended bayesian skyline plots showed fluctuations of effective population sizes and declines during glaciations, and thus also lending support to the importance of vicariance during speciation. There was evidence for positive selection at the ATP6 and possibly ND5 genes, indicating a role in speciation. The findings suggest an important role of ocean current changes in speciation of marine organisms.

  7. Genetic diversity and demographic history of Cajanus spp. illustrated from genome-wide SNPs.

    PubMed

    Saxena, Rachit K; von Wettberg, Eric; Upadhyaya, Hari D; Sanchez, Vanessa; Songok, Serah; Saxena, Kulbhushan; Kimurto, Paul; Varshney, Rajeev K

    2014-01-01

    Understanding genetic structure of Cajanus spp. is essential for achieving genetic improvement by quantitative trait loci (QTL) mapping or association studies and use of selected markers through genomic assisted breeding and genomic selection. After developing a comprehensive set of 1,616 single nucleotide polymorphism (SNPs) and their conversion into cost effective KASPar assays for pigeonpea (Cajanus cajan), we studied levels of genetic variability both within and between diverse set of Cajanus lines including 56 breeding lines, 21 landraces and 107 accessions from 18 wild species. These results revealed a high frequency of polymorphic SNPs and relatively high level of cross-species transferability. Indeed, 75.8% of successful SNP assays revealed polymorphism, and more than 95% of these assays could be successfully transferred to related wild species. To show regional patterns of variation, we used STRUCTURE and Analysis of Molecular Variance (AMOVA) to partition variance among hierarchical sets of landraces and wild species at either the continental scale or within India. STRUCTURE separated most of the domesticated germplasm from wild ecotypes, and separates Australian and Asian wild species as has been found previously. Among Indian regions and states within regions, we found 36% of the variation between regions, and 64% within landraces or wilds within states. The highest level of polymorphism in wild relatives and landraces was found in Madhya Pradesh and Andhra Pradesh provinces of India representing the centre of origin and domestication of pigeonpea respectively. PMID:24533111

  8. Demographic history and adaptation account for clock gene diversity in humans.

    PubMed

    Dall'Ara, I; Ghirotto, S; Ingusci, S; Bagarolo, G; Bertolucci, C; Barbujani, G

    2016-09-01

    Circadian clocks give rise to daily oscillations in behavior and physiological functions that often anticipate upcoming environmental changes generated by the Earth rotation. In model organisms a relationship exists between several genes affecting the circadian rhythms and latitude. We investigated the allele distributions at 116 000 single-nucleotide polymorphisms (SNPs) of 25 human clock and clock-related genes from the 1000Genomes Project, and at a reference data set of putatively neutral polymorphisms. The global genetic structure at the clock genes did not differ from that observed at the reference data set. We then tested for evidence of local adaptation searching for FST outliers under both an island and a hierarchical model, and for significant association between allele frequencies and environmental variables by a Bayesian approach. A total of 230 SNPs in 23 genes, or 84 SNPs in 19 genes, depending on the significance thresholds chosen, showed signs of local adaptation, whereas a maximum of 190 SNPs in 23 genes had significant covariance with one or more environmental variables. Only two SNPs from two genes (NPAS2 and AANAT) exhibit both elevated population differentiation and covariance with at least one environmental variable. We then checked whether the SNPs emerging from these analyses fall within a set of candidate SNPs associated with different chronotypes or sleep disorders. Correlation of five such SNPs with environmental variables supports a selective role of latitude or photoperiod, but certainly not a major one.

  9. Gene flow and demographic history of leopards (Panthera pardus) in the central Indian highlands

    PubMed Central

    Dutta, Trishna; Sharma, Sandeep; Maldonado, Jesús E; Wood, Thomas C; Panwar, Hemendra S; Seidensticker, John

    2013-01-01

    Gene flow is a critical ecological process that must be maintained in order to counteract the detrimental effects of genetic drift in subdivided populations, with conservation benefits ranging from promoting the persistence of small populations to spreading adaptive traits in changing environments. We evaluated historical and contemporary gene flow and effective population sizes of leopards in a landscape in central India using noninvasive sampling. Despite the dramatic changes in land-use patterns in this landscape through recent times, we did not detect any signs that the leopard populations have been through a genetic bottleneck, and they appear to have maintained migration–drift equilibrium. We found that historical levels of gene flow (mean mh = 0.07) were significantly higher than contemporary levels (mean mc = 0.03), and populations with large effective population sizes (Satpura and Kanha Tiger Reserves) are the larger exporters of migrants at both timescales. The greatest decline in historical versus contemporary gene flow is between pairs of reserves that are currently not connected by forest corridors (i.e., Melghat-Pench mh − mc = 0.063; and Kanha-Satpura mh − mc = 0.054). We attribute this reduction in gene flow to accelerated fragmentation and habitat alteration in the landscape over the past few centuries, and suggest protection of forest corridors to maintain gene flow in this landscape. PMID:24062803

  10. Speciation and demographic history of Atlantic eels (Anguilla anguilla and A. rostrata) revealed by mitogenome sequencing.

    PubMed

    Jacobsen, M W; Pujolar, J M; Gilbert, M T P; Moreno-Mayar, J V; Bernatchez, L; Als, T D; Lobon-Cervia, J; Hansen, M M

    2014-11-01

    Processes leading to speciation in oceanic environments without obvious physical barriers remain poorly known. European and American eel (Anguilla anguilla and A. rostrata) spawn in partial sympatry in the Sargasso Sea. Larvae are advected by the Gulf Stream and other currents towards the European/North African and North American coasts, respectively. We analyzed 104 mitogenomes from the two species along with mitogenomes of other Anguilla and outgroup species. We estimated divergence time between the two species to identify major events involved in speciation. We also considered two previously stated hypotheses: one where the ancestral species was present in only one continent but was advected across the Atlantic by ocean current changes and another where population declines during Pleistocene glaciations led to increasing vicariance, facilitating speciation. Divergence time was estimated to ∼3.38 Mya, coinciding with the closure of the Panama Gateway that led to reinforcement of the Gulf Stream. This could have advected larvae towards European/North African coasts, in which case American eel would be expected to be the ancestral species. This scenario could, however, not be unequivocally confirmed by analyses of dN/dS, nucleotide diversity and effective population size estimates. Extended bayesian skyline plots showed fluctuations of effective population sizes and declines during glaciations, and thus also lending support to the importance of vicariance during speciation. There was evidence for positive selection at the ATP6 and possibly ND5 genes, indicating a role in speciation. The findings suggest an important role of ocean current changes in speciation of marine organisms. PMID:24865601

  11. Demographic History of the Genus Pan Inferred from Whole Mitochondrial Genome Reconstructions

    PubMed Central

    Tucci, Serena; de Manuel, Marc; Ghirotto, Silvia; Benazzo, Andrea; Prado-Martinez, Javier; Lorente-Galdos, Belen; Nam, Kiwoong; Dabad, Marc; Hernandez-Rodriguez, Jessica; Comas, David; Navarro, Arcadi; Schierup, Mikkel H.; Andres, Aida M.; Barbujani, Guido; Hvilsom, Christina; Marques-Bonet, Tomas

    2016-01-01

    The genus Pan is the closest genus to our own and it includes two species, Pan paniscus (bonobos) and Pan troglodytes (chimpanzees). The later is constituted by four subspecies, all highly endangered. The study of the Pan genera has been incessantly complicated by the intricate relationship among subspecies and the statistical limitations imposed by the reduced number of samples or genomic markers analyzed. Here, we present a new method to reconstruct complete mitochondrial genomes (mitogenomes) from whole genome shotgun (WGS) datasets, mtArchitect, showing that its reconstructions are highly accurate and consistent with long-range PCR mitogenomes. We used this approach to build the mitochondrial genomes of 20 newly sequenced samples which, together with available genomes, allowed us to analyze the hitherto most complete Pan mitochondrial genome dataset including 156 chimpanzee and 44 bonobo individuals, with a proportional contribution from all chimpanzee subspecies. We estimated the separation time between chimpanzees and bonobos around 1.15 million years ago (Mya) [0.81–1.49]. Further, we found that under the most probable genealogical model the two clades of chimpanzees, Western + Nigeria-Cameroon and Central + Eastern, separated at 0.59 Mya [0.41–0.78] with further internal separations at 0.32 Mya [0.22–0.43] and 0.16 Mya [0.17–0.34], respectively. Finally, for a subset of our samples, we compared nuclear versus mitochondrial genomes and we found that chimpanzee subspecies have different patterns of nuclear and mitochondrial diversity, which could be a result of either processes affecting the mitochondrial genome, such as hitchhiking or background selection, or a result of population dynamics. PMID:27345955

  12. Demographic History of the Genus Pan Inferred from Whole Mitochondrial Genome Reconstructions.

    PubMed

    Lobon, Irene; Tucci, Serena; de Manuel, Marc; Ghirotto, Silvia; Benazzo, Andrea; Prado-Martinez, Javier; Lorente-Galdos, Belen; Nam, Kiwoong; Dabad, Marc; Hernandez-Rodriguez, Jessica; Comas, David; Navarro, Arcadi; Schierup, Mikkel H; Andres, Aida M; Barbujani, Guido; Hvilsom, Christina; Marques-Bonet, Tomas

    2016-01-01

    The genus Pan is the closest genus to our own and it includes two species, Pan paniscus (bonobos) and Pan troglodytes (chimpanzees). The later is constituted by four subspecies, all highly endangered. The study of the Pan genera has been incessantly complicated by the intricate relationship among subspecies and the statistical limitations imposed by the reduced number of samples or genomic markers analyzed. Here, we present a new method to reconstruct complete mitochondrial genomes (mitogenomes) from whole genome shotgun (WGS) datasets, mtArchitect, showing that its reconstructions are highly accurate and consistent with long-range PCR mitogenomes. We used this approach to build the mitochondrial genomes of 20 newly sequenced samples which, together with available genomes, allowed us to analyze the hitherto most complete Pan mitochondrial genome dataset including 156 chimpanzee and 44 bonobo individuals, with a proportional contribution from all chimpanzee subspecies. We estimated the separation time between chimpanzees and bonobos around 1.15 million years ago (Mya) [0.81-1.49]. Further, we found that under the most probable genealogical model the two clades of chimpanzees, Western + Nigeria-Cameroon and Central + Eastern, separated at 0.59 Mya [0.41-0.78] with further internal separations at 0.32 Mya [0.22-0.43] and 0.16 Mya [0.17-0.34], respectively. Finally, for a subset of our samples, we compared nuclear versus mitochondrial genomes and we found that chimpanzee subspecies have different patterns of nuclear and mitochondrial diversity, which could be a result of either processes affecting the mitochondrial genome, such as hitchhiking or background selection, or a result of population dynamics. PMID:27345955

  13. Stock structure and demographic history of the Indo-West Pacific mud crab Scylla serrata

    NASA Astrophysics Data System (ADS)

    Fratini, Sara; Ragionieri, Lapo; Cannicci, Stefano

    2010-01-01

    The increasing exploitation of mangrove forests, without any sustainable planning, has been seriously compromising the survival of this ecosystem and of its exclusive resources. Scylla serrata is one of the most commercially exploited crabs inhabiting mangroves and estuaries of the Indo-Pacific region. This species is extensively harvested, mainly for selling to the tourist market, and, as a consequence, its populations are in constant decline. The aim of the present study was to assess the level of genetic exchange of S. serrata within the Western Indian Ocean (WIO), using a population genetic structure approach. To achieve this goal, we reconstructed the intra-specific geographic pattern of genetic variation by partial sequencing the mitochondrial DNA cytochrome oxidase subunit I, in samples from seven mangrove sites of the WIO. Our data set then encompassed all the sequences for the same genetic marker deposited in Genbank and corresponding to samples from South East Asia, Australia and some Pacific Islands: this allowed us to estimate the level of connectivity among S. serrata populations within its distribution area. Our results show that an unique Scylla serrata metapopulation exists within the WIO; while throughout the entire Indo-Pacific region at least three distinct genetic stocks occur, corresponding to well-defined geographic regions (WIO, Eastern Australia and Pacific Ocean, North-Western Australia). South East China appears as the depositary of the most ancient haplotype and at the present time shares a haplotype with the Red Sea. The WIO populations show the signature of recent population bottlenecks, as expected for populations deeply exploited in a recent past. On the basis of our results, we can conclude that both the S. serrata populations and their habitats, i.e. mangrove forests and estuaries, of the WIO require future management and conservation regulations to avoiding overexploitation of this important key predator and marketable resource.

  14. Origin and demographic history of the endemic Taiwan spruce (Picea morrisonicola).

    PubMed

    Bodare, Sofia; Stocks, Michael; Yang, Jeng-Chuann; Lascoux, Martin

    2013-09-01

    Taiwan spruce (Picea morrisonicola) is a vulnerable conifer species endemic to the island of Taiwan. A warming climate and competition from subtropical tree species has limited the range of Taiwan spruce to the higher altitudes of the island. Using seeds sampled from an area in the central mountain range of Taiwan, 15 nuclear loci were sequenced in order to measure genetic variation and to assess the long-term genetic stability of the species. Genetic diversity is low and comparable to other spruce species with limited ranges such as Picea breweriana, Picea chihuahuana, and Picea schrenkiana. Importantly, analysis using approximate Bayesian computation (ABC) provides evidence for a drastic decline in the effective population size approximately 0.3-0.5 million years ago (mya). We used simulations to show that this is unlikely to be a false-positive result due to the limited sample used here. To investigate the phylogenetic origin of Taiwan spruce, additional sequencing was performed in the Chinese spruce Picea wilsonii and combined with previously published data for three other mainland China species, Picea purpurea, Picea likiangensis, and P. schrenkiana. Analysis of population structure revealed that P. morrisonicola clusters most closely with P. wilsonii, and coalescent analyses using the program MIMAR dated the split to 4-8 mya, coincidental to the formation of Taiwan. Considering the population decrease that occurred after the split, however, led to a much more recent origin.

  15. Demographic History of the Genus Pan Inferred from Whole Mitochondrial Genome Reconstructions.

    PubMed

    Lobon, Irene; Tucci, Serena; de Manuel, Marc; Ghirotto, Silvia; Benazzo, Andrea; Prado-Martinez, Javier; Lorente-Galdos, Belen; Nam, Kiwoong; Dabad, Marc; Hernandez-Rodriguez, Jessica; Comas, David; Navarro, Arcadi; Schierup, Mikkel H; Andres, Aida M; Barbujani, Guido; Hvilsom, Christina; Marques-Bonet, Tomas

    2016-01-01

    The genus Pan is the closest genus to our own and it includes two species, Pan paniscus (bonobos) and Pan troglodytes (chimpanzees). The later is constituted by four subspecies, all highly endangered. The study of the Pan genera has been incessantly complicated by the intricate relationship among subspecies and the statistical limitations imposed by the reduced number of samples or genomic markers analyzed. Here, we present a new method to reconstruct complete mitochondrial genomes (mitogenomes) from whole genome shotgun (WGS) datasets, mtArchitect, showing that its reconstructions are highly accurate and consistent with long-range PCR mitogenomes. We used this approach to build the mitochondrial genomes of 20 newly sequenced samples which, together with available genomes, allowed us to analyze the hitherto most complete Pan mitochondrial genome dataset including 156 chimpanzee and 44 bonobo individuals, with a proportional contribution from all chimpanzee subspecies. We estimated the separation time between chimpanzees and bonobos around 1.15 million years ago (Mya) [0.81-1.49]. Further, we found that under the most probable genealogical model the two clades of chimpanzees, Western + Nigeria-Cameroon and Central + Eastern, separated at 0.59 Mya [0.41-0.78] with further internal separations at 0.32 Mya [0.22-0.43] and 0.16 Mya [0.17-0.34], respectively. Finally, for a subset of our samples, we compared nuclear versus mitochondrial genomes and we found that chimpanzee subspecies have different patterns of nuclear and mitochondrial diversity, which could be a result of either processes affecting the mitochondrial genome, such as hitchhiking or background selection, or a result of population dynamics.

  16. Impact Of Selfing On The Inference Of Demographic History From Whole Genomes In Theobroma cacao L.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Theobroma cacao L (cacao: Malvaceae) is a small tree found naturally in the Amazonian rain forest. An interesting feature of cacao is that it persists in populations of naturally outcrossing and inbreeding plants, as it is a species with a complex system of self-incompatibility, where a fraction of...

  17. Demographic history of Canary Islands male gene-pool: replacement of native lineages by European

    PubMed Central

    Fregel, Rosa; Gomes, Verónica; Gusmão, Leonor; González, Ana M; Cabrera, Vicente M; Amorim, António; Larruga, Jose M

    2009-01-01

    Background The origin and prevalence of the prehispanic settlers of the Canary Islands has attracted great multidisciplinary interest. However, direct ancient DNA genetic studies on indigenous and historical 17th–18th century remains, using mitochondrial DNA as a female marker, have only recently been possible. In the present work, the analysis of Y-chromosome polymorphisms in the same samples, has shed light on the way the European colonization affected male and female Canary Island indigenous genetic pools, from the conquest to present-day times. Results Autochthonous (E-M81) and prominent (E-M78 and J-M267) Berber Y-chromosome lineages were detected in the indigenous remains, confirming a North West African origin for their ancestors which confirms previous mitochondrial DNA results. However, in contrast with their female lineages, which have survived in the present-day population since the conquest with only a moderate decline, the male indigenous lineages have dropped constantly being substituted by European lineages. Male and female sub-Saharan African genetic inputs were also detected in the Canary population, but their frequencies were higher during the 17th–18th centuries than today. Conclusion The European colonization of the Canary Islands introduced a strong sex-biased change in the indigenous population in such a way that indigenous female lineages survived in the extant population in a significantly higher proportion than their male counterparts. PMID:19650893

  18. Phylogeography and demographic history of Babina pleuraden (Anura, Ranidae) in southwestern China.

    PubMed

    Li, Zejun; Yu, Guohua; Rao, Dingqi; Yang, Junxing

    2012-01-01

    Factors that determine genetic structure of species in southwestern China remain largely unknown. In this study, sequences of two mitochondrial genes (COI and cyt b) were determined to investigate the phylogeography and demography of Babina pleuraden, a pond frog endemic to southwestern China. A total of 262 individuals from 22 populations across the entire range of the species were collected. Our results indicate that B. pleuraden comprises five well-supported mitochondrial lineages roughly corresponding to five geographical areas. The phylogeographic structure of B. pleuraden has been shaped primarily by the unique regional responses of the Yunnan Plateau to the rapid uplift of the Qinghai-Tibetan Plateau occurred c. 2.5 Mya (B phrase of Qingzang Movement) and climatic oscillation during middle Pleistocene (c. 0.64-0.36 Mya), rather than by the paleo-drainage systems. The present wide distribution of the species has resulted from recent population expansion (c. 0.053-0.025 Mya) from multiple refugia prior to the Last Glacial Maximum, corresponding to the scenario of "refugia within refugia".

  19. Origin and demographic history of the endemic Taiwan spruce (Picea morrisonicola)

    PubMed Central

    Bodare, Sofia; Stocks, Michael; Yang, Jeng-Chuann; Lascoux, Martin

    2013-01-01

    Taiwan spruce (Picea morrisonicola) is a vulnerable conifer species endemic to the island of Taiwan. A warming climate and competition from subtropical tree species has limited the range of Taiwan spruce to the higher altitudes of the island. Using seeds sampled from an area in the central mountain range of Taiwan, 15 nuclear loci were sequenced in order to measure genetic variation and to assess the long-term genetic stability of the species. Genetic diversity is low and comparable to other spruce species with limited ranges such as Picea breweriana, Picea chihuahuana, and Picea schrenkiana. Importantly, analysis using approximate Bayesian computation (ABC) provides evidence for a drastic decline in the effective population size approximately 0.3–0.5 million years ago (mya). We used simulations to show that this is unlikely to be a false-positive result due to the limited sample used here. To investigate the phylogenetic origin of Taiwan spruce, additional sequencing was performed in the Chinese spruce Picea wilsonii and combined with previously published data for three other mainland China species, Picea purpurea, Picea likiangensis, and P. schrenkiana. Analysis of population structure revealed that P. morrisonicola clusters most closely with P. wilsonii, and coalescent analyses using the program MIMAR dated the split to 4–8 mya, coincidental to the formation of Taiwan. Considering the population decrease that occurred after the split, however, led to a much more recent origin. PMID:24223271

  20. The effects of Medieval dams on genetic divergence and demographic history in brown trout populations

    PubMed Central

    2014-01-01

    Background Habitat fragmentation has accelerated within the last century, but may have been ongoing over longer time scales. We analyzed the timing and genetic consequences of fragmentation in two isolated lake-dwelling brown trout populations. They are from the same river system (the Gudenå River, Denmark) and have been isolated from downstream anadromous trout by dams established ca. 600–800 years ago. For reference, we included ten other anadromous populations and two hatchery strains. Based on analysis of 44 microsatellite loci we investigated if the lake populations have been naturally genetically differentiated from anadromous trout for thousands of years, or have diverged recently due to the establishment of dams. Results Divergence time estimates were based on 1) Approximate Bayesian Computation and 2) a coalescent-based isolation-with-gene-flow model. Both methods suggested divergence times ca. 600–800 years bp, providing strong evidence for establishment of dams in the Medieval as the factor causing divergence. Bayesian cluster analysis showed influence of stocked trout in several reference populations, but not in the focal lake and anadromous populations. Estimates of effective population size using a linkage disequilibrium method ranged from 244 to > 1,000 in all but one anadromous population, but were lower (153 and 252) in the lake populations. Conclusions We show that genetic divergence of lake-dwelling trout in two Danish lakes reflects establishment of water mills and impassable dams ca. 600–800 years ago rather than a natural genetic population structure. Although effective population sizes of the two lake populations are not critically low they may ultimately limit response to selection and thereby future adaptation. Our results demonstrate that populations may have been affected by anthropogenic disturbance over longer time scales than normally assumed. PMID:24903056

  1. Bilateral, atraumatic, proximal tibiofibular joint instability.

    PubMed

    Morrison, Troy D; Shaer, James A; Little, Jill E

    2011-01-01

    Dislocation of the tibiofibular joint is rare and usually results from a traumatic event. Only 1 case of atraumatic proximal tibiofibular joint instability in a 14-year-old girl has been reported in the literature, however this condition might occur more frequently than once thought. A wide range of treatment options exist for tibiofibular dislocations. Currently, the first choice is a conservative approach, and when this fails, surgical means such as resection of the fibula head, arthrodesis, and reconstruction are considered. However, no consensus exists on the most effective treatment. This article reports a unique case of bilateral, atraumatic, proximal tibia and fibular joint instability involving a 30-year-old man with a 20-year history of pain and laxity in the right knee. The patient had no trauma to his knees; he reported 2 immediate family members with similar complaints, which suggests that this case is likely congenital. After conservative approaches proved to be ineffective, the patient underwent capsular reconstruction using free autologous gracilis tendon. At 6-month postoperative follow-up, the patient was pain free with no locking and instability. He then underwent surgery on the left knee. At 1-year follow-up after the second surgery, the patient had no symptoms or restrictions in mobility. We provide an alternative surgical approach to arthrodesis and resection for the treatment of chronic proximal tibiofibular instability. In the treatment of chronic tibiofibular instability, we believe that reconstruction of the tibiofibular joint is a safe and effective choice.

  2. Subtalar joint septic arthritis in a patient with hypogammaglobulinemia.

    PubMed

    Wynes, Jacob; Harris, William; Hadfield, Robert A; Malay, D Scot

    2013-01-01

    The clinical presentation of a monoarticular, red, hot, and swollen joint has many possible diagnoses, including septic arthritis, which is 1 of the most devastating. The morbidity associated with this pathologic process involves permanent joint damage and the potential for progression to systemic illness and, even, mortality. The common risk factors for joint sepsis include a history of rheumatoid arthritis, previous joint surgery, joint prosthesis, intravenous drug abuse, alcoholism, diabetes, previous intra-articular steroid use, and cutaneous ulceration. The diagnosis is primarily determined from the culture results after arthrocentesis and correlation with direct visualization, imaging, and various serologies, including synovial analysis. In the present report, a case of an insidious presentation of subtalar joint septic arthritis and its association with a unique patient presentation concomitant with primary immunodeficiency and culture-proven Myocplasma hominis infection is discussed. Septic arthritis has a predilection for the lower extremities and typically is isolated to the hip or knee, with less common involvement of the ankle or metatarsophalangeal joints. Owing to the uncommon nature of primary immunodeficiency disorders and the paucity of studies discussing their association with septic arthridites, we aimed to raise awareness of subtalar joint septic arthritis and to provide a brief overview of the pathogenesis as it presented in a 33-year-old male with X-linked hypogammaglobulinemia/agammaglobulinema.

  3. Christian Schools and Demographic Change: Two Case Studies

    ERIC Educational Resources Information Center

    Huyser, Mackenzi; Boerman-Cornell, Bill; DeBoer, Kendra

    2011-01-01

    This article explores how two Christian school systems have responded to neighborhood demographic change. Researchers conducted interviews, attended meetings, and reviewed documents to explore two case studies--one of a school struggling to redefine its identity, purpose, and vision in response to demographic change, and another school that has…

  4. China's Demographic Challenge Requires an Integrated Coping Strategy

    ERIC Educational Resources Information Center

    Peng, Xizhe

    2013-01-01

    China has entered into a new stage of demographic dynamics whereby population-related challenges are more complicated than ever before. The current one-child policy should be modified. However, the anticipated impacts of such a policy change should not be over-exaggerated. China's demographic challenge requires an integrated coping strategy.…

  5. The Impact of Extrinsic Demographic Factors on Cantonese Speech Acquisition

    ERIC Educational Resources Information Center

    To, Carol K. S.; Cheung, Pamela S. P.; McLeod, Sharynne

    2013-01-01

    This study modeled the associations between extrinsic demographic factors and children's speech acquisition in Hong Kong Cantonese. The speech of 937 Cantonese-speaking children aged 2;4 to 6;7 in Hong Kong was assessed using a standardized speech test. Demographic information regarding household income, paternal education, maternal education,…

  6. Demographic Faultlines: A Meta-Analysis of the Literature

    ERIC Educational Resources Information Center

    Thatcher, Sherry M. B.; Patel, Pankaj C.

    2011-01-01

    We propose and test a theoretical model focusing on antecedents and consequences of demographic faultlines. We also posit contingencies that affect overall team dynamics in the context of demographic faultlines, such as the study setting and performance measurement. Using meta-analysis structural equation modeling with a final data set consisting…

  7. The demographic basis of population regulation in columbian ground squirrels.

    PubMed

    Dobson, F S; Oli, M K

    2001-09-01

    Environmental factors influence the dynamics and regulation of biological populations through their influences on demographic variables, but demographic mechanisms of population regulation have received little attention. We investigated the demographic basis of regulation of Columbian ground squirrel (Spermophilus columbianus) populations under natural and experimentally food-supplemented conditions. Food supplementation caused substantial increases in population density, and population densities returned to pretreatment levels when the supplementation ended. Control (untreated) populations remained relatively stable throughout the study period (1981-1986). Because food resources regulated the size of the ground squirrel populations, we used life-table response experiment (LTRE) analyses to examine the demographic basis of changes in population growth rate and thus also demographic influences on population regulation. LTRE analyses of two food-manipulated populations revealed that changes in age at maturity and fertility rate of females generally made the largest contributions to observed changes in population growth rate. Thus, our results suggested that abundance of food resources regulated the size of our study populations through the effects of food resources on age at maturity and fertility rates. Our results also indicated that different demographic mechanisms can underlie population regulation under different environmental conditions, because lower juvenile survival substantially contributed to population decline, but in only one of the populations. Demographic analyses of experimental data, such as those presented here, offer a rigorous and unambiguous means to elucidate the demographic basis of population regulation and to help identify environmental factors that underlie dynamics and regulation of biological populations. PMID:18707321

  8. Developing a Global Mindset: Integrating Demographics, Sustainability, Technology, and Globalization

    ERIC Educational Resources Information Center

    Aggarwal, Raj

    2011-01-01

    Business schools face a number of challenges in responding to the business influences of demographics, sustainability, and technology--all three of which are also the fundamental driving forces for globalization. Demographic forces are creating global imbalances in worker populations and in government finances; the world economy faces…

  9. Demographic Estimation from Face Images: Human vs. Machine Performance.

    PubMed

    Han, Hu; Otto, Charles; Liu, Xiaoming; Jain, Anil K

    2015-06-01

    Demographic estimation entails automatic estimation of age, gender and race of a person from his face image, which has many potential applications ranging from forensics to social media. Automatic demographic estimation, particularly age estimation, remains a challenging problem because persons belonging to the same demographic group can be vastly different in their facial appearances due to intrinsic and extrinsic factors. In this paper, we present a generic framework for automatic demographic (age, gender and race) estimation. Given a face image, we first extract demographic informative features via a boosting algorithm, and then employ a hierarchical approach consisting of between-group classification, and within-group regression. Quality assessment is also developed to identify low-quality face images that are difficult to obtain reliable demographic estimates. Experimental results on a diverse set of face image databases, FG-NET (1K images), FERET (3K images), MORPH II (75K images), PCSO (100K images), and a subset of LFW (4K images), show that the proposed approach has superior performance compared to the state of the art. Finally, we use crowdsourcing to study the human perception ability of estimating demographics from face images. A side-by-side comparison of the demographic estimates from crowdsourced data and the proposed algorithm provides a number of insights into this challenging problem. PMID:26357339

  10. Science Achievement, Class Size, and Demographics: The Debate Continues.

    ERIC Educational Resources Information Center

    Miller-Whitehead, Marie

    2001-01-01

    Examined the relationship between school system financial and demographic data and student achievement in the science section of the 1998 Tennessee statewide Terra Nova tests. Results indicate that while many schools had science scale score achievement higher than expected based on system demographics, others should examine a variety of…

  11. Demographic Factors in Adult and Continuing Education. A Keynote Address.

    ERIC Educational Resources Information Center

    Jelinek, James J.

    The basic premise of the book, "Demographic Factors in Adult and Continuing Education," (on which this keynote address is based) is that adult and continuing education are irrelevant, immaterial, and inconsequential unless grounded in social reality. The book identifies more than 1 million demographic factors in the 8 Mountain Plains States. This…

  12. Making the Case for Demographic Data in Extension Programming

    ERIC Educational Resources Information Center

    Curtis, Katherine J.; Verdoff, Daniel; Rizzo, Bill; Beaudoin, James

    2012-01-01

    Understanding one's community is essential for effective Extension programming across all program areas. The use of current and reliable demographic data is crucial for Extension to develop effective education and programming to track change and to uncover hidden community characteristics. We discuss what demographic data are, present…

  13. A Classroom Activity to Illustrate the Demographic Transition

    ERIC Educational Resources Information Center

    Weihe, Paul

    2006-01-01

    A discussion of the Demographic Transition is included in many Environmental Biology or Environmental Science classes. The Demographic Transition occurs as a nation becomes more urban and wealthy, and was widely observed in the twentieth century. The phenomenon includes decreasing family size (fewer children) across generations. In this classroom…

  14. Demographic Estimation from Face Images: Human vs. Machine Performance.

    PubMed

    Han, Hu; Otto, Charles; Liu, Xiaoming; Jain, Anil K

    2015-06-01

    Demographic estimation entails automatic estimation of age, gender and race of a person from his face image, which has many potential applications ranging from forensics to social media. Automatic demographic estimation, particularly age estimation, remains a challenging problem because persons belonging to the same demographic group can be vastly different in their facial appearances due to intrinsic and extrinsic factors. In this paper, we present a generic framework for automatic demographic (age, gender and race) estimation. Given a face image, we first extract demographic informative features via a boosting algorithm, and then employ a hierarchical approach consisting of between-group classification, and within-group regression. Quality assessment is also developed to identify low-quality face images that are difficult to obtain reliable demographic estimates. Experimental results on a diverse set of face image databases, FG-NET (1K images), FERET (3K images), MORPH II (75K images), PCSO (100K images), and a subset of LFW (4K images), show that the proposed approach has superior performance compared to the state of the art. Finally, we use crowdsourcing to study the human perception ability of estimating demographics from face images. A side-by-side comparison of the demographic estimates from crowdsourced data and the proposed algorithm provides a number of insights into this challenging problem.

  15. Demographic and Health Survey of Kenya in 1993.

    PubMed

    1994-01-01

    This report describes the 1993 Kenya Demographic and Health Survey (KDHS) questionnaires, sample frame, setting, research methods and data processing, and main outcome measures of fertility and mortality. The KDHS includes a household questionnaire, a woman's questionnaire, a man's questionnaire, and a services availability questionnaire. The questions were based on the DHS Model B questionnaire for low contraceptive usage countries and written in English for translation into Kiswahili and eight of the most widely spoken local languages. The household questionnaire asked about household members, dwelling characteristics, and sanitation questions. The women's questionnaire asked about background characteristics, reproductive history, knowledge and use of family planning, prenatal and delivery care, breast feeding and weaning, vaccinations, marriage, fertility preferences, husband's background and work, and awareness of AIDS. Interviewers measured the height and weight of women and children. The sample was nationally representative and involved a two-stage design that was stratified by urban and rural residence and district. Questionnaires were pretested. 102 persons were trained over a 4-week period in conducting the fieldwork. There were 12 interviewing teams that began fieldwork on February 18 and completed field work on August 15, 1993. Findings indicate that fertility declined in 10 years from 6.7 to 5.4 children/woman. Fertility was highest in Western Province (6.6 children) and lowest in Nairobi (3.4 children). Ideal family size was 3.7 children. 33% of married women currently used a contraceptive. Child mortality was 96 deaths per 1000 live births. Infant mortality was 62 deaths per 1000 live births. 79% of children aged 12-23 months were fully vaccinated. 33% of children were stunted; 12% were severely stunted; and 6% were wasted. 90% of respondents were aware of HIV transmission from mother to child. 66% perceived themselves at risk.

  16. Demographics of the European Apicultural Industry

    PubMed Central

    Chauzat, Marie-Pierre; Cauquil, Laura; Roy, Lise; Franco, Stéphanie; Hendrikx, Pascal; Ribière-Chabert, Magali

    2013-01-01

    Over the last few years, many European and North American countries have reported a high rate of disorders (mortality, dwindling and disappearance) affecting honeybee colonies (Apis mellifera). Although beekeeping has become an increasingly professional activity in recent years, the beekeeping industry remains poorly documented in Europe. The European Union Reference Laboratory for Honeybee Health sent a detailed questionnaire to each Member State, in addition to Kosovo and Norway, to determine the demographics and state of their beekeeping industries. Based on data supplied by the National Reference Laboratory for honeybee diseases in each European country, a European database was created to describe the beekeeping industry including the number and types of beekeepers, operation size, industry production, and health (notifiable diseases, mortalities). The total number of beekeepers in Europe was estimated at 620 000. European honey production was evaluated at around 220 000 tons in 2010. The price of honey varied from 1.5 to 40 €/kg depending on the country and on the distribution network. The estimated colony winter mortality varied from 7 to 28% depending on the country and the origin of the data (institutional survey or beekeeping associations). This survey documents the high heterogeneity of the apicultural industry within the European Union. The high proportion of non-professional beekeepers and the small mean number of colonies per beekeeper were the only common characteristics at European level. The tremendous variation in European apicultural industries has implication for any comprehensive epidemiological or economic analysis of the industry. This variability needs to be taken into account for such analysis as well as for future policy development. The industry would be served if beekeeping registration was uniformly implemented across member states. Better information on the package bee and queen production would help in understanding the ability of

  17. Demographics of the European apicultural industry.

    PubMed

    Chauzat, Marie-Pierre; Cauquil, Laura; Roy, Lise; Franco, Stéphanie; Hendrikx, Pascal; Ribière-Chabert, Magali

    2013-01-01

    Over the last few years, many European and North American countries have reported a high rate of disorders (mortality, dwindling and disappearance) affecting honeybee colonies (Apis mellifera). Although beekeeping has become an increasingly professional activity in recent years, the beekeeping industry remains poorly documented in Europe. The European Union Reference Laboratory for Honeybee Health sent a detailed questionnaire to each Member State, in addition to Kosovo and Norway, to determine the demographics and state of their beekeeping industries. Based on data supplied by the National Reference Laboratory for honeybee diseases in each European country, a European database was created to describe the beekeeping industry including the number and types of beekeepers, operation size, industry production, and health (notifiable diseases, mortalities). The total number of beekeepers in Europe was estimated at 620,000. European honey production was evaluated at around 220,000 tons in 2010. The price of honey varied from 1.5 to 40 €/kg depending on the country and on the distribution network. The estimated colony winter mortality varied from 7 to 28% depending on the country and the origin of the data (institutional survey or beekeeping associations). This survey documents the high heterogeneity of the apicultural industry within the European Union. The high proportion of non-professional beekeepers and the small mean number of colonies per beekeeper were the only common characteristics at European level. The tremendous variation in European apicultural industries has implication for any comprehensive epidemiological or economic analysis of the industry. This variability needs to be taken into account for such analysis as well as for future policy development. The industry would be served if beekeeping registration was uniformly implemented across member states. Better information on the package bee and queen production would help in understanding the ability of

  18. Prosthetic Joint Infection

    PubMed Central

    Tande, Aaron J.

    2014-01-01

    SUMMARY Prosthetic joint infection (PJI) is a tremendous burden for individual patients as well as the global health care industry. While a small minority of joint arthroplasties will become infected, appropriate recognition and management are critical to preserve or restore adequate function and prevent excess morbidity. In this review, we describe the reported risk factors for and clinical manifestations of PJI. We discuss the pathogenesis of PJI and the numerous microorganisms that can cause this devastating infection. The recently proposed consensus definitions of PJI and approaches to accurate diagnosis are reviewed in detail. An overview of the treatment and prevention of this challenging condition is provided. PMID:24696437

  19. Due Diligence for Students - Geoscience Skills and Demographic Data for Career Planning

    NASA Astrophysics Data System (ADS)

    Keane, C. M.

    2001-05-01

    A major focus of the American Geological Institute's Human Resources program has been providing demographic and employment data so that students and mentors can better understand the dynamics of a career in the geosciences. AGI has a long history of collecting these data for the geoscience community, including 46 years of geoscience enrollments, periodic comprehensive surveys of employment in the discipline, and working closely with other organizations that collect these data. AGI has launched a new suite of surveys to examine the skills desired by employers and the skills provided through a geoscience education. Historical demographic and enrollment data allow a number of the major trends to be examined. These trends include the dominance of industry as employer in the geosciences and how the cyclicity of geoscience employment has become more complex with the development of the environmental sector over the last 30 years. Additionally, demographics are changing rapidly, with a geoscience workforce that is changing rapidly in age, gender, and background. The discipline may also be facing a change in the nature of geoscience employment, with chronic shortages of skilled geoscientists, but will job opportunities actually increase. This may not be as paradoxical as it appears. The geoindustries are attempting to adjust their strategies to dampen business cycles, which then may lead to more stable employment levels for geoscientists, but they are also broadening their vision of who can become competent geoscientists.

  20. Linking physiological approaches to marine vertebrate conservation: using sex steroid hormone determinations in demographic assessments

    PubMed Central

    Labrada-Martagón, Vanessa; Zenteno-Savín, Tania; Mangel, Marc

    2014-01-01

    Sex, age and sexual maturation are key biological parameters for aspects of life history and are fundamental information for assessing demographic changes and the reproductive viability and performance of natural populations under exploitation pressures or in response to environmental influences. Much of the information available on the reproductive condition, length at sexual maturity and sex determinations of endangered species has been derived from direct examination of the gonads in dead animals, either intentionally or incidentally caught, or from stranded individuals. However, morphological data, when used alone, do not provide accurate demographic information in sexually monomorphic marine vertebrate species (e.g. sharks, sea turtles, seabirds and cetaceans). Hormone determination is an accurate and non-destructive method that provides indirect information about sex, reproductive condition and sexual maturity of free-ranging individuals. Correlations between sex steroid concentrations and biochemical parameters, gonadal development and state, reproductive behaviour and secondary external features have been already demonstrated in many species. Different non-lethal approaches (e.g. surgical and mark–recapture procedures), with intrinsic advantages and disadvantages when applied on free-ranging organisms, have been proposed to asses sex, growth and reproductive condition. Hormone determination from blood samples will generate valuable additional demographic information needed for stock assessment and biological conservation. PMID:27293619

  1. Linking physiological approaches to marine vertebrate conservation: using sex steroid hormone determinations in demographic assessments.

    PubMed

    Labrada-Martagón, Vanessa; Zenteno-Savín, Tania; Mangel, Marc

    2014-01-01

    Sex, age and sexual maturation are key biological parameters for aspects of life history and are fundamental information for assessing demographic changes and the reproductive viability and performance of natural populations under exploitation pressures or in response to environmental influences. Much of the information available on the reproductive condition, length at sexual maturity and sex determinations of endangered species has been derived from direct examination of the gonads in dead animals, either intentionally or incidentally caught, or from stranded individuals. However, morphological data, when used alone, do not provide accurate demographic information in sexually monomorphic marine vertebrate species (e.g. sharks, sea turtles, seabirds and cetaceans). Hormone determination is an accurate and non-destructive method that provides indirect information about sex, reproductive condition and sexual maturity of free-ranging individuals. Correlations between sex steroid concentrations and biochemical parameters, gonadal development and state, reproductive behaviour and secondary external features have been already demonstrated in many species. Different non-lethal approaches (e.g. surgical and mark-recapture procedures), with intrinsic advantages and disadvantages when applied on free-ranging organisms, have been proposed to asses sex, growth and reproductive condition. Hormone determination from blood samples will generate valuable additional demographic information needed for stock assessment and biological conservation.

  2. Conservation biology for suites of species: Demographic modeling for Pacific island kingfishers

    USGS Publications Warehouse

    Kesler, D.C.; Haig, S.M.

    2007-01-01

    Conservation practitioners frequently extrapolate data from single-species investigations when managing critically endangered populations. However, few researchers initiate work with the intent of making findings useful to conservation efforts for other species. We presented and explored the concept of conducting conservation-oriented research for suites of geographically separated populations with similar natural histories, resource needs, and extinction threats. An example was provided in the form of an investigation into the population demography of endangered Micronesian kingfishers (Todiramphus cinnamominus). We provided the first demographic parameter estimates for any of the 12 endangered Pacific Todiramphus species, and used results to develop a population projection matrix model for management throughout the insular Pacific. Further, we used the model for elasticity and simulation analyses with demographic values that randomly varied across ranges that might characterize congener populations. Results from elasticity and simulation analyses indicated that changes in breeding adult survival exerted the greatest magnitude of influence on population dynamics. However, changes in nestling survival were more consistently correlated with population dynamics as demographic rates were randomly altered. We concluded that conservation practitioners working with endangered Pacific kingfishers should primarily focus efforts on factors affecting nestling and breeder survival, and secondarily address fledgling juveniles and helpers. Further, we described how the generalized base model might be changed to focus on individual populations and discussed the potential application of multi-species models to other conservation situations. ?? 2007 Elsevier Ltd. All rights reserved.

  3. Linking physiological approaches to marine vertebrate conservation: using sex steroid hormone determinations in demographic assessments.

    PubMed

    Labrada-Martagón, Vanessa; Zenteno-Savín, Tania; Mangel, Marc

    2014-01-01

    Sex, age and sexual maturation are key biological parameters for aspects of life history and are fundamental information for assessing demographic changes and the reproductive viability and performance of natural populations under exploitation pressures or in response to environmental influences. Much of the information available on the reproductive condition, length at sexual maturity and sex determinations of endangered species has been derived from direct examination of the gonads in dead animals, either intentionally or incidentally caught, or from stranded individuals. However, morphological data, when used alone, do not provide accurate demographic information in sexually monomorphic marine vertebrate species (e.g. sharks, sea turtles, seabirds and cetaceans). Hormone determination is an accurate and non-destructive method that provides indirect information about sex, reproductive condition and sexual maturity of free-ranging individuals. Correlations between sex steroid concentrations and biochemical parameters, gonadal development and state, reproductive behaviour and secondary external features have been already demonstrated in many species. Different non-lethal approaches (e.g. surgical and mark-recapture procedures), with intrinsic advantages and disadvantages when applied on free-ranging organisms, have been proposed to asses sex, growth and reproductive condition. Hormone determination from blood samples will generate valuable additional demographic information needed for stock assessment and biological conservation. PMID:27293619

  4. Evaluating the Y chromosomal timescale in human demographic and lineage dating

    PubMed Central

    2014-01-01

    Y chromosome is a superb tool for inferring human evolution and recent demographic history from a paternal perspective. However, Y chromosomal substitution rates obtained using different modes of calibration vary considerably, and have produced disparate reconstructions of human history. Here, we discuss how substitution rate and date estimates are affected by the choice of different calibration points. We argue that most Y chromosomal substitution rates calculated to date have shortcomings, including a reliance on the ambiguous human-chimpanzee divergence time, insufficient sampling of deep-rooting pedigrees, and using inappropriate founding migrations, although the rates obtained from a single pedigree or calibrated with the peopling of the Americas seem plausible. We highlight the need for using more deep-rooting pedigrees and ancient genomes with reliable dates to improve the rate estimation. PMID:25215184

  5. Joint federal/state motor fuel tax compliance project. Fiscal year 1994 midyear report

    SciTech Connect

    1994-11-02

    ;Table of Contents: List of Exhibits; Executive Summary: History of the Joint Federal/State Motor Fuel Tax Compliance Project; Update on Motor Fuel Tax Procedures; Joint Project Results; Status of the Regional Task Forces; Future Program Activities; References; Glossary of Acronyms; List of Exhibits.

  6. Demographic situation and development in Nepal.

    PubMed

    Pradhanang, A L

    1983-01-01

    In Nepal economic development has not kept pace with population growth. The government must develop a vigorous dual program to promote economic development and to reduce population growth. Previous efforts to promote economic development, using a macrolevel approach, failed to improve the economic conditions for the majority of Nepal's citizens. The macrolevel approach required large capital outlays and resulted in an influx of foreign investors and the importation of inappropriate technologies from the developed countries. As a result, urbanization and pollution increased, and both the proportion and the absolute number of poor persons increased. A microlevel approach is now being instituted by the government, and an emphasis is being placed on meeting the basic needs of the poor and on promoting economic self-sufficiency. The country has extensive water resources which can be tapped for irrigation purposes. Nepal also has rich mineral deposits which should be exploited in such a way as to ensure that the profits accrue to the Nepalese. The country has an abundance of manpower resources, but there is a dearth of skilled workers. Unemployment, especially in rural areas, is a serious problem, and efforts should be made to either develop the agricultural sector or create new jobs in other sectors. Nepal's demographic problems include rapid population growth, the influx of a large number of migrants from India, and a high rural to urban migration rate. In 1981, the population size was 15 million, the annual growth rate was 2.6%, the crude birth rate was 38.5, the crude death rate was 18.4, and life expectancy was 47.5 years. The government is currently developing plans 1) to promote the development of core sectors of the economy, 2) to provide family planning services for the poor, 3) to meet the basic needs of rural residents in order to stem the flow of migration to urban areas, 4) to mobilize women to play an active role in the country's development and population

  7. Health & Demographic Surveillance System Profile: The Rufiji Health and Demographic Surveillance System (Rufiji HDSS).

    PubMed

    Mrema, Sigilbert; Kante, Almamy M; Levira, Francis; Mono, Amaniel; Irema, Kahema; de Savigny, Don; Masanja, Honorati

    2015-04-01

    The Rufiji Health and Demographic Surveillance System (HDSS) was established in October 1998 to evaluate the impact on burden of disease of health system reforms based on locally generated data, prioritization, resource allocation and planning for essential health interventions. The Rufiji HDSS collects detailed information on health and survival and provides a framework for population-based health research of relevance to local and national health priorities.In December 2012 the population under surveillance was about 105,503 people, residing in 19,315 households. Monitoring of households and members within households is undertaken in regular 6-month cycles known as 'rounds'. Self reported information is collected on demographic, household, socioeconomic and geographical characteristics. Verbal autopsy is conducted using standardized questionnaires, to determine probable causes of death. In conjunction with core HDSS activities, the ongoing studies in Rufiji HDSS focus on maternal and new-born health, evaluation of safety of artemether-lumefantrine (AL) exposure in early pregnancy and the clinical safety of a fixed dose of dihydroartemisinin-piperaquine (DHA-PQP) in the community. Findings of studies conducted in Rufiji HDSS can be accessed at www.ihi.or.tz/IHI-Digital-Library. PMID:25747869

  8. Joint Custody and Coparenting.

    ERIC Educational Resources Information Center

    Sell, Kenneth D.

    Results are presented of an intensive search of U.S. newspapers and periodicals on the joint custody of children after divorce, where both parents have continued responsibility for parenting and where the children spend part of each week, month, or year with both of the parents. Areas of concern addressed by these materials include the following:…

  9. Human temporomandibular joint morphogenesis.

    PubMed

    Carini, Francesco; Scardina, Giuseppe Alessandro; Caradonna, Carola; Messina, Pietro; Valenza, Vincenzo

    2007-01-01

    Temporomandibular joint morphogenesis was studied. Ranging in age of fetuses examined was from 6 to14 weeks' gestation. Our results showed the condyle so first element that appear between 6 degrees and 8 degrees week (condylar blastema). After a week appear temporal elements. Disk appear at the same time of glenoid blastema and it reaches an advanced differentation before of the condyle and temporal element, so these don't effect machanical compression on mesenchyma where we find the disk. So we think that the disk result of genetic expression and it isn't the result of mechanical compression. The inferior joint cavity appear to 12 week. The superior joint cavity appear to 13-14 week. In conclusion, the appearance of the condyle is the first event during TMJ morphogenesis, with its initial bud, in form of a mesenchymal thickening, becoming detectable between the sixth and eight week of development, when all the large joints of the limbs are already well defined. PMID:18333411

  10. Clad metal joint closure

    SciTech Connect

    Siebert, O.W.

    1985-04-09

    A plasma arc spray overlay of cladding metals is used over joints between clad metal pieces to provide a continuous cladding metal surface. The technique permits applying an overlay of a high melting point cladding metal to a cladding metal surface without excessive heating of the backing metal.

  11. Retrospective Demographic Analysis of Patients Seeking Care at a Free University Chiropractic Clinic

    PubMed Central

    Stevens, Gerald; Campeanu, Michael; Sorrento, Andrew T.; Ryu, Jiwoon; Burke, Jeanmarie

    2016-01-01

    Objective The purpose of this study was to describe the demographics, presenting complaints, and health history of new patients seeking treatment at a free chiropractic clinic within a university health center. Methods A retrospective analysis of patient files from 2008 to 2009 was performed for a free student chiropractic clinic in the Buffalo, NY, area. Demographics, presenting complaints, and health history of new patients seeking treatment were recorded. Results There were 343 new chiropractic patient files. Most patients were between the ages of 18 and 30 years (n = 304, 88%) with an almost equal distribution of men (n = 163, 48%) and women (n = 180, 52%). The patients were mostly single (n = 300, 87%). Patients self-reported that their case histories excluded a current medical diagnosis (n = 261, 76%), previous history of disease (n = 216, 63%), allergies (n = 240, 70%), previous surgical procedures (n = 279, 81%), and medication use (n = 250, 73%). The frequencies of spinal complaints were as follows: lumbar spine, n = 176 (51%); cervical spine, n = 78 (23%); and thoracic spine, n = 44 (13%). Maintenance care, headaches, and spine-related upper and lower extremities complaints accounted for the other 13% of patients treated. Half were chronic (n = 172, 50%), and a third were acute (n=108, 31%). Patients averaged 6 chiropractic visits, with 88% having 11 visits or less. Conclusion This study found that new patients seeking care at a free student chiropractic clinic within a university health center in the Buffalo area mainly consisted of young single adults, with chronic lumbar spine complaints with few comorbidities. PMID:27069428

  12. New Joint Sealants. Criteria, Design and Materials.

    ERIC Educational Resources Information Center

    Building Research Inst., Inc., Washington, DC.

    Contents include--(1) sealing concrete joints, (2) sealing glass and metal joints, (3) metal and glass joint sealants from a fabricator's viewpoint, (4) a theory of adhesion for joint sealants, (5) geometry of simple joint seals under strain, (6) joint sealant specifications from a manufacturer's viewpoint, (7) joint sealant requirements from an…

  13. Influence of harvesting pressure on demographic tactics: Implications for wildlife management

    USGS Publications Warehouse

    Servanty, S.; Gaillard, J.-M.; Ronchi, F.; Focardi, S.; Baubet, E.; Gimenez, O.

    2011-01-01

    Demographic tactics within animal populations are shaped by selective pressures. Exploitation exerts additional pressures so that differing demographic tactics might be expected among populations with differences in levels of exploitation. Yet little has been done so far to assess the possible consequences of exploitation on the demographic tactics of mammals, even though such information could influence the choice of effective management strategies. Compared with similar-sized ungulate species, wild boar Sus scrofa has high reproductive capabilities, which complicates population management. Using a perturbation analysis, we investigated how population growth rates (??) and critical life-history stages differed between two wild boar populations monitored for several years, one of which was heavily harvested and the other lightly harvested. Asymptotic ?? was 1??242 in the lightly hunted population and 1??115 in the heavily hunted population, while the ratio between the elasticity of adult survival and juvenile survival was 2??63 and 1??27, respectively. A comparative analysis including 21 other ungulate species showed that the elasticity ratio in the heavily hunted population was the lowest ever observed. Compared with expected generation times of similar-sized ungulates (more than 6years), wild boar has a fast life-history speed, especially when facing high hunting pressure. This is well illustrated by our results, where generation times were 3??6years in the lightly hunted population and only 2??3years in the heavily hunted population. High human-induced mortality combined with non-limiting food resources accounted for the accelerated life history of the hunted population because of earlier reproduction. Synthesis and applications. For wild boar, we show that when a population is facing a high hunting pressure, increasing the mortality in only one age-class (e.g. adults or juveniles) may not allow managers to limit population growth. We suggest that simulations of

  14. Recent range-wide demographic expansion in a Taiwan endemic montane bird, Steere's Liocichla (Liocichla steerii)

    PubMed Central

    2010-01-01

    Background The subtropical island of Taiwan is an area of high endemism and a complex topographic environment. Phylogeographic studies indicate that vicariance caused by Taiwan's mountains has subdivided many taxa into genetic phylogroups. We used mitochondrial DNA sequences and nuclear microsatellites to test whether the evolutionary history of an endemic montane bird, Steere's Liocichla (Liocichla steerii), fit the general vicariant paradigm for a montane organism. Results We found that while mountains appear to channel gene flow they are not a significant barrier for Steere's Liocichla. Recent demographic expansion was evident, and genetic diversity was relatively high across the island, suggesting expansion from multiple areas rather than a few isolated refugia. Ecological niche modeling corroborated the molecular results and suggested that populations of Steere's Liocichla are connected by climatically suitable habitat and that there was less suitable habitat during the Last Glacial Maximum. Conclusions Genetic and ecological niche modeling data corroborate a single history--Steere's Liocichla was at lower density during the Last Glacial Maximum and has subsequently expanded in population density. We suggest that such a range-wide density expansion might be an overlooked cause for the genetic patterns of demographic expansion that are regularly reported. We find significant differences among some populations in FST indices and an admixture analysis. Though both of these results are often used to suggest conservation action, we affirm that statistically significant results are not necessarily biologically meaningful and we urge caution when interpreting highly polymorphic data such as microsatellites. PMID:20219124

  15. Reconstructing demographic events from population genetic data: the introduction of bumblebees to New Zealand.

    PubMed

    Lye, G C; Lepais, O; Goulson, D

    2011-07-01

    Four British bumblebee species (Bombus terrestris, Bombus hortorum, Bombus ruderatus and Bombus subterraneus) became established in New Zealand following their introduction at the turn of the last century. Of these, two remain common in the United Kingdom (B. terrestris and B. hortorum), whilst two (B. ruderatus and B. subterraneus) have undergone marked declines, the latter being declared extinct in 2000. The presence of these bumblebees in New Zealand provides an unique system in which four related species have been isolated from their source population for over 100 years, providing a rare opportunity to examine the impacts of an initial bottleneck and introduction to a novel environment on their population genetics. We used microsatellite markers to compare modern populations of B. terrestris, B. hortorum and B. ruderatus in the United Kingdom and New Zealand and to compare museum specimens of British B. subterraneus with the current New Zealand population. We used approximate Bayesian computation to estimate demographic parameters of the introduction history, notably to estimate the number of founders involved in the initial introduction. Species-specific patterns derived from genetic analysis were consistent with the predictions based on the presumed history of these populations; demographic events have left a marked genetic signature on all four species. Approximate Bayesian analyses suggest that the New Zealand population of B. subterraneus may have been founded by as few as two individuals, giving rise to low genetic diversity and marked genetic divergence from the (now extinct) UK population. PMID:21645159

  16. Demographic and clinical features of inclusion body myositis in North America

    PubMed Central

    Paltiel, A. David; Ingvarsson, Einar; Lee, Donald K. K.; Leff, Richard L.; Nowak, Richard J.; Petschke, Kurt D.; Richards-Shubik, Seth; Zhou, Ange; Shubik, Martin; O’Connor, Kevin C.

    2016-01-01

    Objective Define the demographics, natural history, and clinical management of patients with inclusion body myositis (IBM). Background Few studies of the demographics, natural history, and clinical management of IBM have been performed in a large patient population. Methods A cross-sectional, self-reporting survey was conducted. Results The mean age of the 916 participants was 70.4 years, the male-to-female ratio was 2:1, and the majority reported difficulty with ambulation and activities of daily living. The earliest symptoms included impaired use and weakness of arms and legs. The mean time from first symptoms to diagnosis was 4.7 years. Half reported that IBM was their initial diagnosis. A composite functional index negatively associated with age, disease duration, and positively associated with participation in exercise. Conclusion These data are valuable for informing patients how IBM manifestations are expected to impair daily living and indicate that self-reporting could be used to establish outcome measures in clinical trials. PMID:25557419

  17. History of Geology.

    ERIC Educational Resources Information Center

    Greene, Mott T.

    1985-01-01

    Discusses: (1) geologists and the history of geology; (2) American historians and the history of geology; (3) history of geology in the 1980s; (4) sources for the history of geology (bibliographies, dictionaries, encyclopedias, handbooks, periodicals, public/official histories, compilations, and books); (5) research opportunities; and (6) other…

  18. [Where is Iowa History?

    ERIC Educational Resources Information Center

    Ruth, Amy, Ed.

    1995-01-01

    This issue of "The Goldfinch" focuses on Iowa history. The booklet is divided into two sections. Section 1, "Features," contains the following: (1) "Looking for History"; (2) "Talking History"; (3) "Climbing the Family Tree"; (4) "Tribal Storytelling"; (5) "News About You"; (6) "History Hangouts"; (7) "Documenting History"; (8) "Textiles Tell the…

  19. Postglacial range shift and demographic expansion of the marine intertidal snail Batillaria attramentaria

    PubMed Central

    Ho, Phuong-Thao; Kwan, Ye-Seul; Kim, Boa; Won, Yong-Jin

    2015-01-01

    To address the impacts of past climate changes, particularly since the last glacial period, on the history of the distribution and demography of marine species, we investigated the evolutionary and demographic responses of the intertidal batillariid gastropod, Batillaria attramentaria, to these changes, using the snail as a model species in the northwest Pacific. We applied phylogeographic and divergence population genetic approaches to mitochondrial COI sequences from B. attramentaria. To cover much of its distributional range, 197 individuals collected throughout Korea and 507 publically available sequences (mostly from Japan) were used. Finally, a Bayesian skyline plot (BSP) method was applied to reconstruct the demographic history of this species. We found four differentiated geographic groups around Korea, confirming the presence of two distinct, geographically subdivided haplogroups on the Japanese coastlines along the bifurcated routes of the warm Tsushima and Kuroshio Currents. These two haplogroups were estimated to have begun to split approximately 400,000 years ago. Population divergence analysis supported the hypothesis that the Yellow Sea was populated by a northward range expansion of a small fraction of founders that split from a southern ancestral population since the last glacial maximum (LGM: 26,000–19,000 years ago), when the southern area became re-submerged. BSP analyses on six geographically and genetically defined groups in Korea and Japan consistently demonstrated that each group has exponentially increased approximately since the LGM. This study resolved the phylogeography of B. attramentaria as a series of events connected over space and time; while paleoceanographic conditions determining the connectivity of neighboring seas in East Asia are responsible for the vicariance of this species, the postglacial sea-level rise and warming temperatures have played a crucial role in rapid range shifts and broad demographic expansions of its

  20. [Demographic analysis of the blue shark, Prionace glauca, in the North Atlantic Ocean].

    PubMed

    Gao, Chun-xia; Dai, Xiao-jie; Tian, Si-quan; Wu, Feng; Zhu, Jiang-feng

    2016-02-01

    The blue shark, Prionace glauca, is the main by-catch species in tuna longline fishery. As one of top species in the oceanic food webs, the blue shark plays an important role in the marine ecosystem. Traditional stock assessment methods are difficult to accurately evaluate the population dynamic for this shark because of limited data. Based on life-history parameters of the blue shark in the North Atlantic, demographic analysis was employed to estimate the demographic parameters and evaluate the potential exploitation for the blue shark. Moreover, we discussed the relationship between age at first capture and critical value of fishing mortality corresponding to the value of intrinsic rate of natural increase 0. The results showed that the survival rate (S) of blue shark from 0.719 to 0.820, intrinsic rate of natural increase (r0) from 0.250 to 0.381, time of population doubling (tx2) from 1.819 to 2.773 years, reproduction rate per generation (R0) from 6.600 to 22.255, and generation time (G) from 8.498 to 10.162 years. The sensitivity analysis for the life history parameters revealed that the uncertainties of natural mortality existed in the first age class, age at maturity and maximum age had slight influence on the demographic parameters. Fishing mortality (Fc) increased with the age at first capture. When the age at first capture (tc) was more than five, there was no obvious relationship between Fc and tc. PMID:27396138