• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 155
  • 149
  • 35
  • 29
  • 15
  • 5
  • 5
  • 3
  • 3
  • 3
  • 3
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 464
  • 130
  • 100
  • 86
  • 84
  • 79
  • 78
  • 73
  • 66
  • 52
  • 47
  • 44
  • 44
  • 41
  • 40
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Analysis of the population genetics and polybrominated diphenyl ether (PBDE) burdens of otters in England and Wales : with case studies of populations in South West England

Pountney, Angela January 2008 (has links)
Otter populations declined drastically across many areas of England and Wales during the 1960s to 1980s. The main cause of this decline is thought to have been high concentrations of organic pollutants, in particular PCBs and dieldrin. Here we look at the health of the present day otter population, focussing on the numbers of otters, the genetic diversity of populations and investigating a possible new organic pollutant threat, polybrominated diphenyl ethers (PBDEs). A non-invasive spraint genotyping study of the otter population inhabiting the River Camel in Cornwall not only revealed that the river was capable of supporting a minimum number of 12 otters over a 9 month period, but gave insight into the ranges and genetic relationships of the individuals using the river system. A further population genetic study was carried out focussing on the River Itchen in Hampshire, a population which declined drastically to just a few isolated individuals before receiving otters through a captive breeding programme. Microsatellite genotyping of tissue samples showed the River Itchen population to be relatively diverse, indicating a successful population recovery, and haplotype analysis reveals that captive bred otters have successfully bred within the River Itchen population. However, haplotype analysis also indicates that the otters used to found the captive breeding programme were unlikely to have originated from a native British population. Concentrations of PBDEs in otters rival the high concentrations observed in many marine mammal species and are approaching the concentrations of PCBs and DDTs already observed in otters. The profile of the PBDE congeners found shows that lower congeners show relative concentrations similar to those observed in many other species of biota, with high BDE-47 dominating the profile and BDE-99 and -100 also found at significant concentrations. Otters also contain relatively high concentrations of the congeners BDE-153 and BDE-209, a trend generally typical of terrestrial top predators. In summary, the otter populations studied appear to be recovering well. However, increasing concentrations of PBDEs may cause problems for otter populations in the future.
52

Dna Profiling of Captive Roseate Spoonbill (Ajaia Ajaja) Populations As a Mechanism of Determining Lineage in Colonial Nesting Birds.

Sawyer, Gregory M. 05 1900 (has links)
Roseate spoonbills are colonial nesting birds with breeding grounds extending from the United States Gulf coast to the pampas of Argentina. The U.S. population suffered a severe bottleneck from 1890 to 1920. The population's recovery was slow and partially credited to migrations from Mexican rookeries, but a gene pool reduction would be expected. Five polymorphic Spoonbill autosomal short tandem repeat (STR) loci [three (GAT)n, one (AAAG)n and one (GT)n] and one Z/W-linked microsatellite exhibiting sex-specific dimorphism were isolated and characterized. The Z/W-linked STR locus accurately confirmed the sex of each bird. Allelic profiles for 51 spoonbills obtained from Dallas (Texas), Fort Worth (Texas) and Sedgwick County (Kansas) zoos revealed a non-continuous distribution of allele frequencies, consistent with the effects of a population bottleneck. Allelic frequencies also differed significantly between the isolated zoo populations. Although extra-pair copulations were suspected and difficult to document, zoos commonly used observational studies of mating pairs to determine familial relationships among adults and offspring. STR parentage analysis of recorded family relationships excluded one or both parents in 10/25 cases studied and it was further possible to identify alternative likely parents in each case. Mistaken familial relationships quickly lead to the loss of genetic variability in captive populations. Here, a decreased heterozygosity (HO) in 2nd generation captive-bred birds was observed at 3 out of 4 loci evaluated. Although these results could not be statistically validated because of the small number of individuals available for study (15 wild birds with no offspring vs. eight 2nd generation captive birds), they are considered biologically important, as decreased HO is an indicator of inbreeding and this apparent decrease occurred within two generations of removal from the wild. Collectively, the evidence obtained from this study suggests that captive spoonbill populations are experiencing rapid loss of diversity from an already depleted wild gene pool.
53

Genetic Variation Among Geographically Disparate Yellow Perch Broodstock Populations

Givens, Chandler Brooke 01 January 2006 (has links)
As a prelude to strain selection for domestication and future marker assisted selection, genetic variation revealed by microsatellite DNA was evaluated in yellow perch, Perca flavescens, from four wild North American populations collected in 2003-2004 (Maine, ME; New York, NY; North Carolina, NC; and Pennsylvania, PA), and two captive populations (Michigan, MI; Ohio, OH). For the loci examined, levels of heterozygosity ranged from He = 0.04 to 0.88, genetic differentiation was highly significant among all population pairs, and effective migration ranged from low (Nem = 0.3) to high (Nem = 4.5). Deviation from Hardy-Weinberg 1equilibrium was regularly observed indicating significant departures from random mating. Instantaneous measures of inbreeding within these populations ranged from near zero to moderate (median F = 0.16) and overall inbreeding levels averaged FIS = 0.18. Estimates of genetic diversity, Φ ST and genetic distance were highest between Michigan and all other populations and lowest between New York and Ohio. Genetic differentiation among populations did not correlate with geographic distance. Overall, the patterns of variation exhibited by the captive (Michigan and Ohio) populations were similar to patterns exhibited by the other allegedly wild populations, indicating that the spawning and management practices to date have not significantly reduced levels of genetic variation.
54

Gene flowanalysis of anopheles arabiensis (Diptera:culicidae) populations in southern africa using microsatellite DNA markers

Mouatcho, Joel Claude 26 October 2006 (has links)
0009014A Msc thesis Science Animal plant and environmental sciences / Anopheles arabiensis is considered an important vector of human malaria in the southern African region where the disease is the major cause of morbidity and mortality. Gene flow plays an important role in malaria control with the spread of insecticide resistance. The main objectives of this study were to (i) measure the genetic variability within and between five populations (Botswana, Namibia, South Africa, Swaziland and Zimbabwe) of wild An. arabiensis and (ii) estimate the level of gene flow between natural populations across the Southern-limits of An. arabiensis. A total of 1225 An. arabiensis specimens were identified out of 1300 mosquitoes collected from 2000-2003 with the sample sizes ranging from 180-292 per country. Variation at four microsatellite markers was investigated on non-denaturing polyacrylamide gels. The results showed fewer variations between populations (2.96%) than within populations (82.60%) suggesting considerable homogeneity. However, estimates of gene flow (Nm) calculated from mean FST and RST statistics were relatively low, 1.14 and 1.19 respectively, suggesting somewhat restricted gene flow between populations. The occurrence of gene flow within subpopulations of An. arabiensis in Zimbabwe but not in South Africa is interesting with regard to the spread of insecticide resistance in Zimbabwe. The results presented here are obviously subject to the limitations inherent in manual, silver staining method of analysing microsatellite DNA markers. It is possible that a different set of results would be obtained if an Automated Sequencing Analyzer were used. ii
55

Culex quinquefasciatus (Diptera: Culicidae): aspectos da manipulação genética e estudos populacionais utilizando marcadores microssatélites / Culex quinquefasciatus (Diptera: Culicidae): aspects of genetic manipulation and population Characterization using microsatellites

Wilke, Andre Barretto Bruno 12 April 2013 (has links)
O avanço na distribuição geográfica de mosquitos vetores é seguido pela emergência de vírus e doenças em novas áreas para as quais não há disponibilidade de vacinas efetivas e drogas terapêuticas específicas são insuficientes. Métodos de controle de mosquitos tradicionais perderam efetividade, devido principalmente a grande capacidade reprodutiva e flexibilidade genômica dos mosquitos. Controle químico cada vez mais tornase restrito, acarretando na urgente necessidade de novas formas de controle. A liberação de machos carregando um gene letal dominante (RIDL) oferece novas abordagens aplicáveis ao controle de mosquitos e ainda assim ecológicas e espécie específica. Mosquitos Culex quinquefasciatus foram transformados com sucesso apenas uma vez, apesar do esforço de diversos laboratórios em obter uma linhagem transgênica estável. Foi desenvolvido um método de expressão transiente em mosquitos Culex, que insere plasmídeos contendo genes efetores na hemolinfa e tecidos subjacentes do mosquito. Foi observada a expressão da proteína fluorescente DsRed2, em mosquitos Culex quinquefasciatus adultos mediada por plasmídeos. Esta expressão pode ser considerada um importante passo na transformação de mosquitos Culex, além de potencial uso em estratégias de controle genético e interações gênicas. Para que novas formas de controle sejam realmente efetivas é vital que se conheça a estrutura genética da população alvo. Marcadores moleculares têm sido extensivamente utilizados em estudos filogenéticos e taxonômicos de diversas espécies de insetos. Microssatélites são de grande utilidade para observar estruturas populacionais, tanto em âmbito geográfico, quanto na escala evolucionária. Foi possível observar a formação de clusters e de padrões genéticos distintos entre as populações analisadas, criando um panorama genético dos mosquitos Culex quinquefasciatus coletados no Brasil / The increase in the geographic distribution of vectors is accompanied by the emergence of viruses and diseases in new areas. There are insufficient specific therapeutic drugs available and there are no reliable vaccines to malaria or dengue. Most mosquito control measures have failed to achieve their goals, mostly because of the mosquitos great reproductive capacity and genomic flexibility. Chemical control is increasingly restricted therefore other strategies for mosquito control are desperately needed. Releasing of Insects Carrying a Dominant Lethal Gene (RIDL) offers a new approach that can be applied to mosquitoes yet environmentally friendly and species-specific. Culex quinquefasciatus mosquitoes have been successfully genetically modified only once, despite the efforts of several laboratories to transform and establish a stable strain. We have adapted a transient gene expression method, in Culex, that delivers plasmid DNA directly to the mosquito hemolymph and additional tissues. We were able to express DsRed2 fluorescent protein in adult Culex quinquefasciatus mosquitoes by injecting plasmids directly into their thorax. The expression of DsRed2 in adult Culex quinquefasciatus mosquitoes is an important stepping stone to genetic transformation and the potential use of new control strategies and genetic interactions. If new methods of control are to become really effective it is vital to know the genetic structure of the target population. Molecular markers have been widely used in phylogenetic and taxonomic studies of various groups of insects. Microsatellites are very useful for observing the population structure both geographically and evolutionarily. It has been possible to observe the formation of clusters and distinct genetic patterns among the analyzed populations creating a panorama of Culex quinquefasciatus mosquitoes populations present in Brazil
56

Distribuição da frequência alélica de STRs preconizados pelo sistema CODIS na capital e no Departamento Central do Paraguai / Distribution of the allelic frequency of STRs recommended by the CODIS system in the capital and in the Central Department of Paraguay

Recalde, Tamara Soledad Frontanilla 10 December 2018 (has links)
Um dos maiores desafios na área forense é, sem dúvida, a identificação humana. O DNA tem sido o responsável por uma verdadeira revolução das técnicas de identificação nas últimas décadas a partir do estudo e da identificação de polimorfismos entre determinados marcadores moleculares existentes nos indivíduos. Os marcadores recomendados para a obtenção de perfis genéticos são loci de regiões microssatélite do DNA, também designados de Short Tandem Repeats (STR). O número de repetições dos marcadores STR é variável entre os indivíduos, criando polimorfismo e tornando-os, desta forma, ótimos marcadores para identificação humana. O objetivo desse trabalho foi estabelecer a distribuição da frequência alélica de 16 STRs preconizados no sistema CODIS, na capital e no Departamento Central de Paraguai. Foram estudadas 300 amostras de saliva coletadas com NUCLEIC-CARD(TM) Collection Device System, de indivíduos paraguaios dentre 20 e 70 anos de idade, morando em uma das 20 cidades estudadas. Para o processamento foi utilizado o kit AmpFLSTR Identifiler Direct PCR Amplification® seguindo as fases de genotipagem, amplificação e eletroforese capilar. Foi possível estabelecer o perfil genético de 259 amostras bem como os parâmetros forenses e, assim, calcular os loci mais polimórficos os quais foram FGA e D18S51 utilizando os softwares GenAlEx 6.5, Arlequin 3.5 e R 2.5. A distribuição das frequências alélicas de cada loci analisado permitiu estabelecer a caracterização genética da população estudada. Foi possível confirmar que a população do Paraguai se encontra em equilíbrio Hardy-Weinberg, com uma diversidade genética intrapopulacional de 0.794915 +/- 0.398307 e interpopulacional determinada pelo índice de fixação (FST) de 0.01112. A partir desse estudo, foi possível determinar as frequências alélicas de 15 STRs utilizados no sistema CODIS nacapital e no Departamento Central do Paraguai bem como a caracterização genética e os parâmetros forenses da população estudada. Todos os loci estudados na população paraguaia foram considerados muito informativos e úteis para a solução de problemas relacionados com identificação humana na amostra analisada / One of the biggest challenges in Forensic Sciences is undoubtedly human identification. DNA has been responsible for a true revolution in identification techniques in the last decades from the study and identification of polymorphisms between certain molecular markers in individuals. The recommended markers for obtaining genetic profiles are loci of DNA microsatellite regions, also called Short Tandem Repeats (STR). The number of repetitions of STR markers is variable among individuals, creating polymorphism and thus making them excellent markers for human identification. The aim of this study was to establish the distribution of the allelic frequency of 16 STRs recommended in the CODIS system, in the capital and in the Central Department of Paraguay. We studied 300 saliva samples collected from NUCLEIC-CARD (TM) Collection Device System of Paraguayan individuals between 20 and 70 years-old, living in one of the 20 cities studied. For the processing, the AmpFLSTR Identifiler Direct PCR Amplification® kit was used following the phases of genotyping, amplification and capillary electrophoresis. It was possible to establish the genetic profile of 259 samples as well as the forensic parameters and thus to calculate the most polymorphic loci which were FGA and D18S51 using the software GenAlEx 6.5, Arlequin 3.5 and R 2.5. The distribution of the allelic frequencies of each analyzed loci allowed establishing the genetic characterization of the studied population. It was possible to confirm that the population of Paraguay is in Hardy-Weinberg equilibrium, with an intrapopulational genetic diversity of 0.8046 +/- 0.0120 and interpopulational determined by the fixation index (FST) of 0.01112. From this study, it was possible to determine the allelic frequencies of 15 STRs used in the CODIS system in the capital and in the Central Department of Paraguay, as well as the genetic characterization and forensic parameters of the studied population. All the loci studied in the Paraguayan population were considered veryinformative and useful for the solution of problems related to human identification in the analyzed sample
57

Microsatellite instability and cyclooxygenase-2 expression in gastric carcinogensis. / CUHK electronic theses & dissertations collection

January 2001 (has links)
by Wai-keung Leung. / Thesis (M.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 217-232). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.
58

Distribuição da frequência alélica de STRs preconizados pelo sistema CODIS na capital e no Departamento Central do Paraguai / Distribution of the allelic frequency of STRs recommended by the CODIS system in the capital and in the Central Department of Paraguay

Tamara Soledad Frontanilla Recalde 10 December 2018 (has links)
Um dos maiores desafios na área forense é, sem dúvida, a identificação humana. O DNA tem sido o responsável por uma verdadeira revolução das técnicas de identificação nas últimas décadas a partir do estudo e da identificação de polimorfismos entre determinados marcadores moleculares existentes nos indivíduos. Os marcadores recomendados para a obtenção de perfis genéticos são loci de regiões microssatélite do DNA, também designados de Short Tandem Repeats (STR). O número de repetições dos marcadores STR é variável entre os indivíduos, criando polimorfismo e tornando-os, desta forma, ótimos marcadores para identificação humana. O objetivo desse trabalho foi estabelecer a distribuição da frequência alélica de 16 STRs preconizados no sistema CODIS, na capital e no Departamento Central de Paraguai. Foram estudadas 300 amostras de saliva coletadas com NUCLEIC-CARD(TM) Collection Device System, de indivíduos paraguaios dentre 20 e 70 anos de idade, morando em uma das 20 cidades estudadas. Para o processamento foi utilizado o kit AmpFLSTR Identifiler Direct PCR Amplification® seguindo as fases de genotipagem, amplificação e eletroforese capilar. Foi possível estabelecer o perfil genético de 259 amostras bem como os parâmetros forenses e, assim, calcular os loci mais polimórficos os quais foram FGA e D18S51 utilizando os softwares GenAlEx 6.5, Arlequin 3.5 e R 2.5. A distribuição das frequências alélicas de cada loci analisado permitiu estabelecer a caracterização genética da população estudada. Foi possível confirmar que a população do Paraguai se encontra em equilíbrio Hardy-Weinberg, com uma diversidade genética intrapopulacional de 0.794915 +/- 0.398307 e interpopulacional determinada pelo índice de fixação (FST) de 0.01112. A partir desse estudo, foi possível determinar as frequências alélicas de 15 STRs utilizados no sistema CODIS nacapital e no Departamento Central do Paraguai bem como a caracterização genética e os parâmetros forenses da população estudada. Todos os loci estudados na população paraguaia foram considerados muito informativos e úteis para a solução de problemas relacionados com identificação humana na amostra analisada / One of the biggest challenges in Forensic Sciences is undoubtedly human identification. DNA has been responsible for a true revolution in identification techniques in the last decades from the study and identification of polymorphisms between certain molecular markers in individuals. The recommended markers for obtaining genetic profiles are loci of DNA microsatellite regions, also called Short Tandem Repeats (STR). The number of repetitions of STR markers is variable among individuals, creating polymorphism and thus making them excellent markers for human identification. The aim of this study was to establish the distribution of the allelic frequency of 16 STRs recommended in the CODIS system, in the capital and in the Central Department of Paraguay. We studied 300 saliva samples collected from NUCLEIC-CARD (TM) Collection Device System of Paraguayan individuals between 20 and 70 years-old, living in one of the 20 cities studied. For the processing, the AmpFLSTR Identifiler Direct PCR Amplification® kit was used following the phases of genotyping, amplification and capillary electrophoresis. It was possible to establish the genetic profile of 259 samples as well as the forensic parameters and thus to calculate the most polymorphic loci which were FGA and D18S51 using the software GenAlEx 6.5, Arlequin 3.5 and R 2.5. The distribution of the allelic frequencies of each analyzed loci allowed establishing the genetic characterization of the studied population. It was possible to confirm that the population of Paraguay is in Hardy-Weinberg equilibrium, with an intrapopulational genetic diversity of 0.8046 +/- 0.0120 and interpopulational determined by the fixation index (FST) of 0.01112. From this study, it was possible to determine the allelic frequencies of 15 STRs used in the CODIS system in the capital and in the Central Department of Paraguay, as well as the genetic characterization and forensic parameters of the studied population. All the loci studied in the Paraguayan population were considered veryinformative and useful for the solution of problems related to human identification in the analyzed sample
59

Hybridisation and introgression of exotic Cervus (nippon and canadensis) with red deer (Cervus elaphus) in the British Isles

Smith, Stephanie Lindsay January 2013 (has links)
Europe’s largest population of wild red deer (Cervus elaphus) resides in the British Isles and has been present since the end of the last ice age, c. 11,000BP. Since the mid-19th century, multiple introductions of Japanese sika (Cervus nippon) and wapiti (Cervus canadensis) have taken place across the British Isles. While wapiti introductions have generally gone extinct, sika have thrived and expanded and now often live in sympatry with red deer. Hybridisation between these species has been demonstrated in captivity and in the wild. This study sought to determine the extent of hybridisation and introgression between red and sika across large parts of the British Isles and elucidate some of its potential consequences. Chapter 2 addresses the extent of hybridisation and introgression across Scotland and NW England. A total of 2984 samples from the North Highlands, the central Highlands, the Hebrides, Kintyre and the English Lake District were genotyped at 22 microsatellite loci, which are highly diagnostic for red and sika and strongly diagnostic for red and wapiti and a mitochondrial marker that is diagnostic for red and sika, alongside 49 wapiti samples from Canada. Microsatellite data was analysed using the Bayesian clustering program Structure 2.3 to determine the extent of admixture between species. There was some evidence for very low-level introgression by wapiti into a small number of Scottish red deer (<0.2% of total). Only two areas (both in Kintyre, Argyll) showed extensive introgression with collapse of assortative mating between red and sika (50.4% and 61.8% of sampled individuals were hybrid in West Loch Awe and South Kintyre, respectively). However, rare and widely scattered individuals with low-level sika introgression or cytonuclear disequilibrium suggest hybridisation has occurred in several other places in mainland Scotland and Cumbria in the past without subsequent loss of assortative mating. Chapter 3 addresses the extent of hybridisation in Ireland. There are now an estimated 4,000 red deer in Ireland and their numbers are increasing. It has recently been determined that the red deer in Killarney, County Kerry are descended from an ancient (c. 5,000BP) introduction and therefore merit genetic conservation. Introduction of exotic species, including Japanese sika and North America wapiti, since the 19th century have primarily occurred via the now defunct Powerscourt Park, County Wicklow, which was the source of many translocations to the rest of Ireland as well as to the UK. 374 deer samples from across Ireland were analysed as in Chapter 2. Wapiti introgression was again very low, with trace amounts of introgression detected in a small proportion of samples (0.53%), whilst 41% of 197 deer sampled in Co. Wicklow and 47% of 15 deer sampled in Co. Cork were red-sika hybrids according to either their nuclear genome or mitochondrial haplotype. No pure red deer were detected in Co. Wicklow, suggesting that in this region the red deer has disappeared following hybridisation. Whilst no hybrids were detected among 37 red samples and 77 sika samples in Co. Kerry, the Co. Cork hybrids pose a threat to the Killarney populations due to their proximity. Chapter 4 investigates population genetic structure within red and sika populations across the British Isles and investigates whether low-level introgression by the other species influences the resolved population structure. Structure analysis was conducted separately using 2307 ‘pure’ red deer individuals and 752 ‘pure’ sika animals from the British Isles (defined as Q > 0.95 for red and Q < 0.05 for sika) and then on reduced sample sizes using more stringent purity criteria (Q ≥ 0.99 and Q ≤ 0.01). As might be predicted, the more stringent criteria removed individuals in areas known to contain advanced backcrosses. In red deer, there was some evidence for a loss of within-species population structure under the more stringent criteria, while for sika there was not. Datasets were also analysed using Discriminate Analysis of Principal Components; a multivariate method designed to infer and describe genetic population structure. In red deer, both analytical approaches confirmed the strong separation of the deer on Harris and Lewis from others, and there is support for clusters typified by the other Hebridean islands, Kintyre, central and North Scotland and the English sites. Among sika, both approaches supported the likelihood of three clusters which are presumably the result of bottleneck events as each introduction was made. Chapter 5 investigates the phenotypic consequences of hybridisation by three approaches. Firstly, carcass weight was regressed against genetically-determined hybrid scores (at two stringency levels, see Chapter 4) and heterozygosity (in terms of red and sika alleles). Among hybrids, carcass weight is linearly related to hybrid score (Q) and there is some evidence for a positive relationship with heterozygosity. This suggests that additive genetic variation explains variation in carcass weight to a greater extent than heterosis. Secondly, analysis of five case studies representing individual putative hybrids submitted by stalkers from areas without known hybridisation, two proved to be hybrids, while the other three were pure sika. Lastly, in regions known to contain hybrids, the accuracy of ranger-assigned phenotype averaged 78% and revealed that in Scotland accuracy tends to decline as an individual becomes more genetically intermediate; whilst in Co. Wicklow it is the identification of pure parental animals that is more challenging. In conclusion, the existence of rare and widely scattered advanced red-sika backcrosses with low-level nuclear introgression and/or mitochondrial introgression (e.g. in North of Scotland, Cumbria) highlight that some hybridisation events are followed by extensive backcrossing without the breakdown of assortative mating, while others are followed by the generation of a hybrid swarm (e.g. in South Kintyre, West Loch Awe, Co. Wicklow, Co. Cork). Phenotypic traits can become intermediate due to hybridisation and this may facilitate further gene flow and hybridisation. New molecular tools including next generation sequencing (NGS) will enable better understanding the hybridisation process and its phenotypic consequences in this and other systems.
60

Genetic differentiation in Alewife populations using microsatellite loci

Chilakamarri, Sunita R 31 May 2005 (has links)
"Local genetic adaptation and homing behavior in anadromous fish favors the formation of local populations across their geographic range of distribution. Spawning- and natal-site fidelity repeated over generations restricts gene flow and allows genetic differences to accumulate resulting in reproductive isolation. This leads to progressive genetic differentiation and population structuring among different river populations. Alewife, Alosa pseudoharengus, are anadromous fish which are estimated to have high rates of reproductive fidelity and hence might show population structuring among different breeding streams. Alewife are fish of economic importance since they have both commercial and recreational value. Alewife populations have been declining over the past decades and conservation measures to restore the populations have been implemented. Since maintaining genetic integrity of natural populations is one of the main concerns, identification of population structure can assist in designing appropriate restocking programs. In this study, I used microsatellite markers developed for shad to study population structuring in alewife. Samples were collected from two sites in Connecticut and one in Lake Michigan and genetic differentiation among these populations was estimated using five microsatellite loci. My studies indicate that microsatellite loci developed for shad can be used for alewife. Results from this preliminary study indicated subtle but significant genetic differentiation among populations. This suggests that care should be taken when restocking alewife from different sites in order to maintain genetic diversity among these populations."

Page generated in 0.031 seconds