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A landscape genetics approach to unravel the complex evolutionary history of the Iberian honey bee hybrid zone

Pinto, M. Alice; Johnston, J. Spencer; Azevedo, João; Brandão, Andreia; Moura, Inês; Muñoz, Irene; De la Rúa, Pilar; Patton, John C.
Fonte: IPB, IUFRO Publicador: IPB, IUFRO
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
46.09%
While landscape genetics is in its infancy, it is a rapidly growing research field in part owing to the increasing availability of powerful molecular and analytical tools. By integrating landscape ecology, spatial statistics and population genetics, landscape genetics is allowing an unprecedented understanding of the microevolutionary processes shaping genetic variation, which has important implications for the advance of ecological and evolutionary knowledge. The Iberian honey bee provides a great model system to address evolutionary questions using a landscape genetics framework. First, previous studies suggest that the Iberian honey bee has a hybrid origin and hybrid zones have been favored by evolutionary biologists as powerful natural laboratories to study evolutionary processes. Second, with the publication of the honey bee genome and development of high‐density SNP markers, powerful tools are now available to dissect the relative importance of neutral and adaptive forces in shaping the Iberian honey bee hybrid zone, a goal of central importance as it leads to more robust inferences of demographic history and to identification of adaptive divergence. Herein, we will present an ongoing research project on the Iberian honey bee hybrid zone where the tools of landscape genetics and population genomics will be combined to unravel the challenging evolutionary history of the Iberian honey bee.

Estudo de mutações no gene BRCA na população Ashkenazi e não Ashkenazi com histórico para câncer de mama e/ou ovário.; Study of mutations in the BRCA genes in Ashkenazi and non-Ashkenazi jewish population with familial breast and/or ovarian cancer.

Cunha, Danielle Renzoni da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 07/04/2011 PT
Relevância na Pesquisa
46.05%
O câncer de mama é um dos mais incidentes no mundo e mais comum na população feminina. Algumas populações possuem maior risco para o câncer de mama e ovário devido a presença de mutações fundadoras nos genes BRCA1 e BRCA2 como ocorre nos Judeus Ashkenazi (JA). Os testes genéticos para detecção de mutações de ponto nos genes BRCA1 e BRCA2 foram realizados em 106 indivíduos com e sem origem judaica (IOA) através do rastreamento por dHPLC e sequenciamento. A distribuição das mutações fundadoras no gene BRCA1 foi de cerca de 55 % para 185delAG e 5382isnC no gene BRCA1 e 12 % para 6174delT, no gene BRCA2. Estas mutações também foram detectadas em 7,4 % dos casos no grupo IOA e 84,2% no grupo JA (p< 0,001). Mutações fundadoras espanholas e portuguesas, 330 A>G (11,11 %) e 7966C>T (7,4 %), foram detectadas no IOA. Os carcinomas de mama e ovário foram mais frequentes nos dois grupos, cerca de 70 % e 20 %, respectivamente. No grupo IOA foram diagnosticados carcinomas de mama masculino (9,5 %) e trompa uterina (2,9 %), e carcinoma endometrióide em 11,8 % no grupo JA.; Breast cancer is one of the most commun tumors in women. Some populations shows higher risks for breast and ovarian cancers due to founder mutations in the BRCA1 and BRCA2 genes...

Internal genetic structure and outcrossing rate in a natural population of Araucaria angustifolia (Bert.) O. Kuntze

Mantovani, Adelar; Morellato, L. Patrícia C.; Dos Reis, Maurício S.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 466-472
ENG
Relevância na Pesquisa
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The internal genetic structure and outcrossing rate of a population of Araucaria angustifolia (Bert.) O. Kuntze were investigated using 16 allozyme loci. Estimates of the mean number of alleles per loci (1.6), percentage of polymorphic loci (43.8%), and expected genetic diversity (0.170) were similar to those obtained for other gymnosperms. The analysis of spatial autocorrelation demonstrated the presence of internal structure in the first distance classes (up to 70 m), suggesting the presence of family structure. The outcrossing rate was high (0.956), as expected for a dioecious species. However, it was different from unity, indicating outcrossings between related individuals and corroborating the presence of internal genetic structure. The results of this study have implications for the methodologies used in conservation collections and for the use or analysis of this forest species. © The American Genetic Association. 2006. All rights reserved.

The population genetic structure of Rhizoctonia solani AG-3PT from potato in the Colombian Andes

Ferrucho, Rosa L.; Ceresini, Paulo C.; Ramirez-Escobar, Ursula M.; McDonald, Bruce A.; Cubeta, Marc A.; García-Domínguez, Celsa
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 862-869
ENG
Relevância na Pesquisa
46.03%
The soilborne fungus Rhizoctonia solani anastomosis group 3 (AG-3PT) is a globally important potato pathogen. However, little is known about the population genetic processes affecting field populations of R. solani AG-3PT, especially in the South American Colombian Andes, which is near the center of diversity of the two most common groups of cultivated potato, Solanum tuberosum and S. phureja. We analyzed the genetic structure of 15 populations of R. solani AG-3PT infecting potato in Colombia using 11 simple-sequence repeat (SSR) markers. In total, 288 different multilocus genotypes were identified among 349 fungal isolates. Clonal fractions within field populations were 7 to 33%. R ST statistics indicated a very low level of population differentiation overall, consistent with high contemporary gene flow, though moderate differentiation was found for the most distant southern populations. Genotype flow was also detected, with the most common genotype found widely distributed among field populations. All populations showed evidence of a mixed reproductive mode, including both asexual and sexual reproduction, but two populations displayed evidence of inbreeding. © 2013 The American Phytopathological Society.

Estudos genético-moleculares em Giardia duodenalis : caracterização da diversidade genética e análises populacionais em amostras clínicas e ambientais na região metropolitana de Campinas, São Paulo, Brasil = Genetic and molecular studies in Giardia duodenalis: molecular characterization of genetic diversity and population genetic analysis in clinical and environmental samples in the metropolitan region of Campinas, São Paulo, Brazil; Genetic and molecular studies in Giardia duodenalis : molecular characterization of genetic diversity and population genetic analysis in clinical and environmental samples in the metropolitan region of Campinas, São Paulo, Brazil

Mauricio Durigan
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 24/02/2015 PT
Relevância na Pesquisa
46.06%
Giardia duodenalis é um protozoário flagelado que parasita o homem e diversos animais domésticos e selvagens. Este parasito causa a doença giardiose que é uma das mais prevalentes doenças parasitárias de veiculação hídrica do mundo, responsável por aproximadamente 280 milhões de casos anualmente. Existe uma considerável variabilidade genética em G. duodenalis, de modo que seus isolados foram divididos em oito grupos genéticos (A-H), dois dos quais (A e B) são encontrados tanto em humanos quanto em animais. Os demais grupos (C-H) parasitam outros animais e apresentam maior especificidade a determinados hospedeiros não humanos. A contaminação ambiental por Giardia tem sido amplamente descrita embora esses estudos, em sua maioria, são realizados no nível de identificação de espécie. Há falta de estudos que correlacionam a contaminação ambiental e infecções clínicas na mesma região. O presente trabalho teve como objetivo principal contribuir para o conhecimento da diversidade genética da espécie Giardia duodenalis. Primeiramente, foi realizada a genotipagem multilocos dos principais grupos genéticos de G. duodenalis na região metropolitana de Campinas. Foram encontrados grupos genéticos associados principalmente a infecções humanas bem como isolados com potencial zoonótico em amostras ambientais e obtidas de outros animais. Foi encontrado um alto percentual (25%) de amostras com grupos genéticos mistos e um elevado número de haplótipos distintos...

Genealogical data in population medical genetics: field guidelines

Poletta,Fernando A.; Orioli,Ieda M.; Castilla,Eduardo E.
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
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This is a guide for fieldwork in Population Medical Genetics research projects. Data collection, handling, and analysis from large pedigrees require the use of specific tools and methods not widely familiar to human geneticists, unfortunately leading to ineffective graphic pedigrees. Initially, the objective of the pedigree must be decided, and the available information sources need to be identified and validated. Data collection and recording by the tabulated method is advocated, and the involved techniques are presented. Genealogical and personal information are the two main components of pedigree data. While the latter is unique to each investigation project, the former is solely represented by gametic links between persons. The triad of a given pedigree member and its two parents constitutes the building unit of a genealogy. Likewise, three ID numbers representing those three elements of the triad is the record field required for any pedigree analysis. Pedigree construction, as well as pedigree and population data analysis, varies according to the pre-established objectives, the existing information, and the available resources.

Population Genetics of Anopheles coluzzii Immune Pathways and Genes

Rottschaefer, Susan M.; Crawford, Jacob E.; Riehle, Michelle M.; Guelbeogo, Wamdaogo M.; Gneme, Awa; Sagnon, N’Fale; Vernick, Kenneth D.; Lazzaro, Brian P.
Fonte: Genetics Society of America Publicador: Genetics Society of America
Tipo: Artigo de Revista Científica
Publicado em 30/12/2014 EN
Relevância na Pesquisa
45.97%
Natural selection is expected to drive adaptive evolution in genes involved in host–pathogen interactions. In this study, we use molecular population genetic analyses to understand how natural selection operates on the immune system of Anopheles coluzzii (formerly A. gambiae “M form”). We analyzed patterns of intraspecific and interspecific genetic variation in 20 immune-related genes and 17 nonimmune genes from a wild population of A. coluzzii and asked if patterns of genetic variation in the immune genes are consistent with pathogen-driven selection shaping the evolution of defense. We found evidence of a balanced polymorphism in CTLMA2, which encodes a C-type lectin involved in regulation of the melanization response. The two CTLMA2 haplotypes, which are distinguished by fixed amino acid differences near the predicted peptide cleavage site, are also segregating in the sister species A. gambiae (“S form”) and A. arabiensis. Comparison of the two haplotypes between species indicates that they were not shared among the species through introgression, but rather that they arose before the species divergence and have been adaptively maintained as a balanced polymorphism in all three species. We additionally found that STAT-B...

The Impact of Divergence Time on the Nature of Population Structure: An Example from Iceland

Helgason, Agnar; Palsson, Snaebjorn; Stefansson, Hreinn; St. Clair, David; Andreassen, Ole A.; Kong, Augustine; Stefansson, Kari; Price, Alkes; Reich, David Emil
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
46.07%
The Icelandic population has been sampled in many disease association studies, providing a strong motivation to understand the structure of this population and its ramifications for disease gene mapping. Previous work using 40 microsatellites showed that the Icelandic population is relatively homogeneous, but exhibits subtle population structure that can bias disease association statistics. Here, we show that regional geographic ancestries of individuals from Iceland can be distinguished using 292,289 autosomal single-nucleotide polymorphisms (SNPs). We further show that subpopulation differences are due to genetic drift since the settlement of Iceland 1100 years ago, and not to varying contributions from different ancestral populations. A consequence of the recent origin of Icelandic population structure is that allele frequency differences follow a null distribution devoid of outliers, so that the risk of false positive associations due to stratification is minimal. Our results highlight an important distinction between population differences attributable to recent drift and those arising from more ancient divergence, which has implications both for association studies and for efforts to detect natural selection using population differentiation.

Association of PCSK1 rs6234 with Obesity and Related Traits in a Chinese Han Population

Li, Huaixing; Loos, Ruth J. F.; Wu, Hongyu; Yu, Zhijie; Lin, Xu; Zhang, Cuilin; Qi, Qibin; Liu, Chen; Hu, Frank B.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
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46.02%
Background: Common variants in PCSK1 have been reported to be associated with obesity in populations of European origin. We aimed to replicate this association in Chinese. Methodology/Principal Findings: Two PCSK1 variants rs6234 and rs6235 (in strong LD with each other, r2 = 0.98) were genotyped in a population-based cohort of 3,210 Chinese Hans. The rs6234 was used for further association analyses with obesity and related traits. We found no significant association of rs6234 with obesity, overweight, BMI, waist circumference, or body fat percentage (P>0.05) in all participants. However, the rs6234 G-allele showed a significant association with increased risk of combined phenotype of obesity and overweight (OR 1.21[1.03–1.43], P = 0.0193) and a trend toward association with obesity (OR 1.25[0.98–1.61], P = 0.08) in men, but not in women (P≥0.29). Consistently, the rs6234 G-allele showed significant association with increased BMI (P = 0.0043), waist circumference (P = 0.008) and body fat percentage (P = 0.0131) only in men, not in women (P≥0.24). Interestingly, the rs6234 G-allele was significantly associated with increased HOMA-B (P = 0.0059) and decreased HOMA-S (P = 0.0349) in all participants. Conclusion/Significance: In this study...

African Ancestry and Its Correlation to Type 2 Diabetes in African Americans: A Genetic Admixture Analysis in Three U.S. Population Cohorts

Cheng, Ching-Yu; Haiman, Christopher A.; Patterson, Nick; Elizabeth, Selvin; Akylbekova, Ermeg L.; Brancati, Frederick L.; Coresh, Josef; Boerwinkle, Eric; Taylor, Herman A.; Henderson, Brian E.; Wilson, James G.; Reich, David Emil; Tandon, Arti; Altshule
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
46.01%
The risk of type 2 diabetes is approximately 2-fold higher in African Americans than in European Americans even after adjusting for known environmental risk factors, including socioeconomic status (SES), suggesting that genetic factors may explain some of this population difference in disease risk. However, relatively few genetic studies have examined this hypothesis in a large sample of African Americans with and without diabetes. Therefore, we performed an admixture analysis using 2,189 ancestry-informative markers in 7,021 African Americans (2,373 with type 2 diabetes and 4,648 without) from the Atherosclerosis Risk in Communities Study, the Jackson Heart Study, and the Multiethnic Cohort to 1) determine the association of type 2 diabetes and its related quantitative traits with African ancestry controlling for measures of SES and 2) identify genetic loci for type 2 diabetes through a genome-wide admixture mapping scan. The median percentage of African ancestry of diabetic participants was slightly greater than that of non-diabetic participants (study-adjusted difference = 1.6%, (P)<0.001). The odds ratio for diabetes comparing participants in the highest vs. lowest tertile of African ancestry was 1.33 (95% confidence interval 1.13–1.55)...

Integrating empirical data and population genetic simulations to study the genetic architecture of type 2 diabetes

Agarwala, Vineeta
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
Relevância na Pesquisa
45.97%
Most common diseases have substantial heritable components but are characterized by complex inheritance patterns implicating numerous genetic and environmental factors. A longstanding goal of human genetics research is to delineate the genetic architecture of these traits - the number, frequencies, and effect sizes of disease-causing alleles - to inform mapping studies, elucidate mechanisms of disease, and guide development of targeted clinical therapies and diagnostics. Although vast empirical genetic data has now been collected for common diseases, different and contradictory hypotheses have been advocated about features of genetic architecture (e.g., the contribution of rare vs. common variants). Here, we present a framework which combines multiple empirical datasets and simulation studies to enable systematic testing of hypotheses about both global and locus-specific complex trait architecture. We apply this to type 2 diabetes (T2D).

Integration of Sequence Data from a Consanguineous Family with Genetic Data from an Outbred Population Identifies PLB1 as a Candidate Rheumatoid Arthritis Risk Gene

Okada, Yukinori; Diogo, Dorothee; Greenberg, Jeffrey D.; Mouassess, Faten; Achkar, Walid A. L.; Fulton, Robert S.; Denny, Joshua C.; Gupta, Namrata; Mirel, Daniel; Gabriel, Stacy; Li, Gang; Kremer, Joel M.; Pappas, Dimitrios A.; Carroll, Robert J.; Eyler,
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
46.08%
Integrating genetic data from families with highly penetrant forms of disease together with genetic data from outbred populations represents a promising strategy to uncover the complete frequency spectrum of risk alleles for complex traits such as rheumatoid arthritis (RA). Here, we demonstrate that rare, low-frequency and common alleles at one gene locus, phospholipase B1 (PLB1), might contribute to risk of RA in a 4-generation consanguineous pedigree (Middle Eastern ancestry) and also in unrelated individuals from the general population (European ancestry). Through identity-by-descent (IBD) mapping and whole-exome sequencing, we identified a non-synonymous c.2263G>C (p.G755R) mutation at the PLB1 gene on 2q23, which significantly co-segregated with RA in family members with a dominant mode of inheritance (P = 0.009). We further evaluated PLB1 variants and risk of RA using a GWAS meta-analysis of 8,875 RA cases and 29,367 controls of European ancestry. We identified significant contributions of two independent non-coding variants near PLB1 with risk of RA (rs116018341 [MAF = 0.042] and rs116541814 [MAF = 0.021], combined P = 3.2×10−6). Finally, we performed deep exon sequencing of PLB1 in 1,088 RA cases and 1,088 controls (European ancestry)...

Population genetics and conservation strategies for the West Indian manatee (Trichechus manatus Linnaeaus,1758) in Brazil

Luna, Fábia de Oliveira; Passavante, José Zanon de Oliveira (Orientador); Bonde, Robert K. (Coorientador); Hunter, Margaret (COorientadora)
Fonte: Universidade Federal de Pernambuco Publicador: Universidade Federal de Pernambuco
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
45.98%
The West Indian manatee (Trichechus manatus) and the Amazonian manatee (Trichechus inunguis) belong to the mammalian Order Sirenia, classified respectively as critically endangered and as vulnerable in Brazil. Both species have been hunted commercially since the sixteenth century, resulting in a drastic reduction or elimination of manatees in some places. This hunting pressure may have caused isolation of the populations resulting in geographic genetic isolation, with a reduction of their genetic diversity. The objective of this study is to understand the genetic diversity and population structure of the West Indian manatee (T. manatus) in Brazil; verify the existence of hybridization between the manatees T. manatus and T. inungus; define the degree of relatedness of individuals in captivity; and provide strategies for the conservation of the species. In northeastern Brazil, a large number of dependent calves strand on beaches. Many of these calves have been rescued alive and rehabilitated for future release. Previously, the identification of release sites did not take into account the genetic issues. Through this study, it has been possible to identify suitable release sites based on phylogenetic traits of the manatees. The genetic structure of the population was studied using nuclear DNA in the program STRUCTURE...

Extreme population-dependent linkage disequilibrium detected in an inbreeding plant species, Hordeum vulgare

Caldwell, K.; Russell, J.; Langridge, P.; Powell, W.
Fonte: Genetics Publicador: Genetics
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
56.01%
In human genetics a detailed knowledge of linkage disequilibrium (LD) is considered a prerequisite for effective population-based, high-resolution gene mapping and cloning. Similar opportunities exist for plants; however, differences in breeding system and population history need to be considered. Here we report a detailed study of localized LD in different populations of an inbreeding crop species. We measured LD between and within four gene loci within the region surrounding the hardness locus in three different gene pools of barley (Hordeum vulgare). We demonstrate that LD extends to at least 212 kb in elite barley cultivars but is rapidly eroded in related inbreeding ancestral populations. Our results indicate that haplotype-based sequence analysis in multiple populations will provide new opportunities to adjust the resolution of association studies in inbreeding crop species.; Katherine S. Caldwell, Joanne Russell, Peter Langridge, and Wayne Powell

Amino acid covariation in a functionally important human immunodeficiency virus type 1 protein region is associated with population subdivision

Da Silva, J.
Fonte: Genetics Publicador: Genetics
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
55.97%
The frequently reported amino acid covariation of the highly polymorphic human immunodeficiency virus type 1 (HIV-1) exterior envelope glycoprotein V3 region has been assumed to reflect fitness epistasis between residues. However, nonrandom association of amino acids, or linkage disequilibrium, has many possible causes, including population subdivision. If the amino acids at a set of sequence sites differ in frequencies between subpopulations, then analysis of the whole population may reveal linkage disequilibrium even if it does not exist in any subpopulation. HIV-1 has a complex population structure, and the effects of this structure on linkage disequilibrium were investigated by estimating within- and among-subpopulation components of variance in linkage disequilibrium. The amino acid covariation previously reported is explained by differences in amino acid frequencies among virus subpopulations in different patients and by nonsystematic disequilibrium among patients. Disequilibrium within patients appears to be entirely due to differences in amino acid frequencies among sampling time points and among chemokine coreceptor usage phenotypes of virus particles, but not source tissues. Positive selection explains differences in allele frequencies among time points and phenotypes...

Genome-Wide Association Studies of Asthma in Population-Based Cohorts Confirm Known and Suggested Loci and Identify an Additional Association near HLA

Ramasamy, Adaikalavan; Kuokkanen, Mikko; Vedantam, Sailaja; Gajdos, Zofia Katherine; Couto Alves, Alexessander; Lyon, Helen N.; Ferreira, Manuel A. R.; Strachan, David P.; Zhao, Jing Hua; Abramson, Michael J.; Brown, Matthew A.; Coin, Lachlan; Dharmage, S
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
46.14%
Rationale: Asthma has substantial morbidity and mortality and a strong genetic component, but identification of genetic risk factors is limited by availability of suitable studies. Objectives: To test if population-based cohorts with self-reported physician-diagnosed asthma and genome-wide association (GWA) data could be used to validate known associations with asthma and identify novel associations. Methods: The APCAT (Analysis in Population-based Cohorts of Asthma Traits) consortium consists of 1,716 individuals with asthma and 16,888 healthy controls from six European-descent population-based cohorts. We examined associations in APCAT of thirteen variants previously reported as genome-wide significant (P<5x\(10^{−8}\)) and three variants reported as suggestive (P<5×\(10^{−7}\)). We also searched for novel associations in APCAT (Stage 1) and followed-up the most promising variants in 4,035 asthmatics and 11,251 healthy controls (Stage 2). Finally, we conducted the first genome-wide screen for interactions with smoking or hay fever. Main Results: We observed association in the same direction for all thirteen previously reported variants and nominally replicated ten of them. One variant that was previously suggestive, rs11071559 in RORA...

Testing for concordant equilibria between population samples

Huttley, Gavin Austin; Wilson, Susan
Fonte: Genetics Society of America Publicador: Genetics Society of America
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.03%
A substantial body of theory has been developed to assess the effect of evolutionary forces on the distribution of genotypes, both single and multilocus, within populations. One area where the potential for application of this theory has not been fully appreciated concerns the extent to which population samples differ. Within populations, the divergence of genotype or haplotype frequencies from that expected under Hardy-Weinberg (HW) or linkage equilibrium can be measured as disequilibria coefficients. To assess population samples for concordant equilibria, an analytical framework for comparing disequilibria coefficients between populations is necessary. Here we present log-linear models to evaluate such hypotheses. These models have broad utility ranging from conventional population genetics to genetic epidemiology. We demonstrate the use of these log-linear models (1) as a test for genetic association with disease and (2) as a test for different levels of linkage disequilibria between human populations.

Genetic structure, conservation genetics and evidence of speciation by range expansion in shy and white-capped albatrosses

Abbott, Cathryn; Double, Michael
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.97%
Six variable microsatellite loci were used to examine genetic structuring in the closely related shy albatross (Thalassarche cauta) and white-capped albatross (T. steadi). First, levels of genetic differentiation between the species, and among three populations within each species, were analysed using AMOVA, FST and RST. We found high levels of genetic structuring and detected many unshared alleles between the species, which provide strong evidence against any contemporary gene flow between them. Within each species, shy albatross populations were found to be genetically distinct whereas white-capped albatross populations were undifferentiated, which implies that dispersal events are much rarer in the former than in the latter. These results formed the basis for the recommendation that the three white-capped albatross populations (as a whole) and each shy albatross population be treated as separate units for conservation. Second, levels of genetic diversity and allelic patterns in shy and white-capped albatrosses were assessed for whether they support earlier mtDNA results suggesting that shy albatrosses arose through range expansion of white-capped albatrosses. All measures indicated lower genetic diversity within shy albatrosses than within white-capped albatrosses and upheld the hypothesis that shy albatrosses were founded by white-capped albatrosses.

The recovery of populations of bush rat Rattus fuscipes in forest fragments following major population reduction

Lindenmayer, David; Cunningham, Ross; Peakall, Rodney
Fonte: British Ecological Society Publicador: British Ecological Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.02%
1. Understanding the recovery of populations after disturbance is critical to many aspects of applied population management, ranging from the development of conservation strategies to pest control. We used a controlled and replicated field experiment linked to a genetic study to examine the rate and mechanism of population recovery of the Australian bush rat after severe experimental population reduction. 2. The main factors examined were perturbation treatment (removal of animals, removal followed by restocking, no removal), patch size and patch isolation. Although large numbers of animals were removed from many patches, on average populations recovered to pretreatment levels within 2 years. Populations rebounded to levels that appeared to approximate patch carrying capacity. Initially small populations recovered to a small size and those that were large were also large 24 months later. No significant relationships between population recovery and patch size and isolation were identified. 3. There was an effect of initial population size on proportional trapping success: a higher proportion of initially large populations was trapped than smaller ones. 4. Genetic analyses revealed a significant genetic change following experimental perturbation. Rapid population recovery was mostly via residual animals (and their off-spring) that escaped capture...

Mutation rate of 7 X-STRs of common use in population genetics

Glesmann,Laura A.; Martina,Pablo F.; Vidal Rioja,Lidia; Catanesi,Cecilia I.
Fonte: BAG. Journal of basic and applied genetics Publicador: BAG. Journal of basic and applied genetics
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2009 EN
Relevância na Pesquisa
46.01%
Microsatellite loci analysis is a relevant tool in population genetic studies and also in paternity testing. In this field the X-chromosome STR loci are widely used for female offspring testing but their mutation rates are scarcely known. In this work we performed a mutation rate analysis of seven STR markers located in the X- chromosome specific region, in mother-son pairs and father-mother-daughter trios. Among 1015 allele transfers, we found only one change for a mother-daughter transmission in the DXS9898 locus, consisting of a loss of one single repeat. This finding allowed us to estimate a general mutation rate of μ=9.85 x 10-4 (2.49 x 10-4 - 5.49 x 10-2) which can be applied to population studies. This value is consistent with other reports on autosomal STR loci, suggesting that similar molecular mechanisms are acting on X and autosomal repetitive markers.