A Dissertation Submitted to the Faculty of Science of the University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of Master of Science. / Impala are an ancient and successful specdes whose biogeography differs from other bovids. A detailed electrophoretic investigation of genetic variability within and between subpopulations found six polymorphic loci, CK-C"', GPl"', MPr\ PEP-Jr, PGM-2'" and PROT-2'" in a sample of 464 impala collected from 10 localities in southern Africa. Average gene diversity was 0,047. Between-population gene diversity was normal for bovid species. Allele frequency differences and genetic distances revealed low levels of subdivision into three broad regions. Wright's FST (0,035) revealed a significant yet low level of population subdivision. The distributions of single-locus heterozygosities and allele frequencies were significantly different to those predicted during mutation-drift equi librium, indicating that non-equilibrium conditions may prevail and that the population may be recovering from a recent bottleneck. / AC 2018

Univ., Diss.--Göteborg, 2006. / Enth. außerdem 5 Zeitschriftenaufsätze.

Thesis (M.Ag.Sci. 1977) from the Department of Genetics, University of Adelaide. / Addendum in end pocket.

Thesis (doctoral)--University of Helsinki, 1988. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (p. 25-29).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 77-80).

Thesis (Ph.D.)--Göteborg University, 2006. / Includes bibliographical references.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1977. / Bibliography: leaves 110-118. / Microfiche. / x, 118 leaves ill. (some col.)

Made available in DSpace on 2014-06-11T19:26:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-04-29Bitstream added on 2014-06-13T19:53:55Z : No. of bitstreams: 1 silva_em_me_botib.pdf: 872118 bytes, checksum: f09b7402718a1296ef6e16914c27dded (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Bryconinae compreende um grupo de peixes com um grande número de espécies distribuídas em sistemas hidrográficos da América Central e da América do Sul. Análises cromossômicas baseadas em técnicas citogenéticas clássicas revelaram que todas as espécies estudadas até o momento apresentam cariótipos similares sem a presença de cromossomos sexuais heteromórficos. Visando ampliar os dados genéticos acerca das relações entre as espécies deste gênero e sobre a evolução cromossômica deste grupo, o objetivo do presente estudo foi isolar e caracterizar fragmentos de DNA associados a um determinado sexo e repetições de DNA satélite em Brycon cephalus e B. orbignyanus. Desta forma, uma análise de marcadores RAPD (“Random Amplified Polymorphic DNA”) e uma dinâmica de digestão enzimática de DNA total foram realizadas. Sessenta e seis primers decâmeros foram utilizados em PCR revelando um fragmento de RAPD, composto por 535 pb, presente em fêmeas de B. cephalus. Dados de hibridização em membrana (“dot-blot”) e de um marcador SCAR (“Sequence Characterized Amplified Region”) desenvolvido confirmaram a especificidade deste fragmento a fêmeas desta espécie e revelaram sua ausência em duas outras espécies do gênero - B. orbignyanus e B. lundii.Digestões enzimáticas de DNA de B. cephalus e B. orbignyanus não evidenciaram diferenças entre machos e fêmeas. Por outro lado, as digestões realizadas com EcoRV, EcoRI, NotI, XbaI e XhoI em B. cephalus levaram à identificação de fragmentos de aproximadamente 250-300 pb em ambos os sexos que provavelmente correspondem a repetições de DNA satélite, denominadas de SatBc1, SatBc2, SatBc3, SatBc4 e SatBc5, respectivamente. A enzima HindIII permitiu a visualização de duas bandas de restrição com cerca de 650 e 850 pb (denominadas de SatBo1 e SatBo2) em machos e fêmeas de B. orbignyanus... / Bryconinae stands for a fish group with several species that have been reported in South and Central America hydrographic systems. Chromosome analyses based on classical cytogenetic techniques have revealed that all species so far studied present similar karyotypes with no heteromorphic sex chromosomes. In order to improve genetic data on the species relationships and chromosome evolution, the purpose of the present study was to isolate and characterize sex-associated DNA fragments and satellite repeats in Brycon cephalus and B. orbignyanus. For this purpose, a random amplified polymorphic DNA (RAPD) assay and a genomic DNA restriction digestion analysis were performed. Sixty six decamer primers were used in PCR revealing a RAPD fragment, composed by 535 bp, present in females of B. cephalus. Data on dot-blot hybridization and on a designed SCAR (Sequence Characterized Amplified Region) marker confirmed its female-specificity in this species and revealed its absence in two other species of the genus - B. orbignyanus and B. lundii. Genomic DNA restriction digestions in B. cephalus and B. orbignyanus resulted in no differences between sexes of both species. However, EcoRV, EcoRI, NotI, XbaI and XhoI DNA digestions in B. cephalus led to the identification of fragments of approximately 250-300 bp in both sexes that probably correspond to satellite DNA repeats, denominated SatBc1, SatBc2, SatBc3, SatBc4 and SatBc5, respectively.The HindIII enzyme permitted the visualization of two restriction bands of around 650 and 850 bp (named as SatBo1 and SatBo2) in males and females of B. orbignyanus. Characterization of the SatBc1 fragment isolated from B. cephalus indicated that its monomeric unit is constituted by 255 bp and 52.9% AT rich. The obtained RAPD data can lead to the supposition that B. cephalus may present heteromorphic sex chromosomes that should be in an early phase... (Complete abstract click electronic access below)

<p>    </p> <p>In honey bees, male fertility is directly involved in colony fitness. Males not only provide fifty percent of colony genetics, but they also provide material benefits involved with female fertility. Recent evidence suggests there is tremendous variation in drone fertility. Of drones which are sexually mature, as few as one in ten may be able to produce enough sperm to successfully inseminate a queen. If drones are not producing healthy sperm, their mates will not produce healthy colonies. Despite this, we have very little understanding of precisely how variation in drone reproductive quality is generated. Specifically, we know comparatively little about the role genetics plays in shaping drone reproductive traits. This standing genetic variation can contribute to phenotypic variation observed among honey bee stocks and contribute to the success (or failure) of colonies. <strong>The major goal of this thesis is to identify the major mechanisms and genes driving genotypic and phenotypic variation in honey bee males. </strong>First, we used a population genetics approach to estimate the evolutionary impact of haploid selection <strong>(Chapter 2) </strong>and variation in sexual selection <strong>(Chapter 3) </strong>on male genes. In <strong>Chapter 2</strong>, we found genes expressed by males had an increased genetic diversity, rate of adaptation, and more efficient purifying selection than non-haploid selected female-expression genes. This suggests haploid and sexually- expressed genes experience increases in the rate of molecular evolution. In <strong>Chapter 3</strong>, we found selection on sperm length shifted over evolutionary time within corbiculate bees, resulting in different strengths of sexual selection. As selection for sperm length intensified in male bees, there was rapid evolution of expression patterns and gene sequences associated with male-biased genes. Second, we used a quantitative genetics approach to connect genetic variation to the trait components of fitness <strong>(Chapter 4)</strong>. We identified key genes connected to honey bee male sperm and maturity traits. These genes also appear to have different rates of evolution. Overall, we combined both population and quantitative genetic approaches to provide comprehensive insights into the evolution of honey bee male genotypes and phenotypes. This powerful approach allowed me to identify the genetic and mechanistic underpinnings driving variation in fitness-related traits. This information can be used to identify candidate genes associated with honey bee male fitness. </p>

Resumo: Os chamados cromossomos supranumerários ou B, também denominados de cromossomos extras ou acessórios, são elementos genômicos adicionais e não homólogos aos do complemento A. Alguns estudiosos consideram que os cromossomos B poderiam ter sido originados dos cromossomos do complemento cariotípico e posteriormente seguido sua própria evolução, mas existem também outras hipóteses a respeito disso. A presença desse tipo de cromossomo tem sido descrita em animais e plantas e estes elementos estruturais extras constituem material genético de origem e função geralmente desconhecidas. As mudanças no complemento cariotípico relacionadas à presença dos cromossomos B e a sua distribuição têm sido descritas como participantes dos mecanismos evolutivos em vertebrados. Entre os peixes, principalmente da fauna Neotropical, a presença de cromossomos B apresenta-se de forma expressiva entre as espécies, sendo de grande interesse para estudos sobre sua estrutura, origem e função no processo de diversificação biológica. Estes cromossomos têm um comportamento diferencial, quando submetidos à coloração por bandamento C, geralmente se apresentando total ou parcialmente heterocromáticos e às vezes eucromáticos. Essas características podem ser uma forte evidência da sua provável origem e evolução independente. Portanto, sabendo-se que o entendimento sobre os cromossomos B depende de intensivas análises citogenéticas e moleculares, e com o intuito de entender a natureza dos processos envolvidos na evolução desses cromossomos, no presente trabalho foram analisados cinco populações de Moenkhausia sanctaefilomenae e as espécies Moenkhausia cosmops e Moenkhausia oligolepis pertencentes a diferentes bacias hidrográficas brasileiras. Foram utilizadas em exemplares de M. sanctaefilomenae, população do ribeirão Araquá, técnicas citogenéticas básicas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The so-called supernumerary or B chromosomes, also known as extra or accessory chromosomes, are additional genomic elements non-homologous to those from the standard or A complement. Some experts argue that B chromosome would have been derived from the standard karyotype that have undergone their own evolutionary history, bout other hypotheses have also been proposed. The occurrence of these chromosomes has been described in both animals and plants but the origin and function of such extra structural elements remains poorly understood. Karyotypical changes related to the presence of B chromosomes and their distribution have been reported as evolutionary mechanisms in vertebrates. Among fish, mainly neotropical ones, B chromosomes are expressively found in many species, justifying their great interest for studies about structure, origin and function during biological diversification processes. These chromosomes have a differential behavior when submitted to C-banding, being entirely or partially heterochromatic or else euchromatic. These features might be a reliable evidence of their probable independent origin and evolution. Therefore, the understanding about B chromosomes depends on intensive cytogenetic and molecular analyses, and in order to comprehend the nature of their evolutionary processes, five populations of Moenkhausia sanctaefilomenae and the species Moenkhausia cosmops and Moenkhausia oligolepis from different Brazilian hydrographic basins were analyzed in the present work. Basic cytogenetic (Giemsa staining, silver-stained NOR location and C-banding) and molecular (base-specific fluorochromes, 18S rDNA and 5S rDNA fluorescent in situ hybridization) techniques were applied on specimens of M. sanctaefilomenae from Araquá stream, to verify particularities related to heterochromatin distribution and B chromosomes, representing an interesting model for further molecular... (Complete abstract click electronic access below) / Orientador: Fausto Foresti / Coorientador: Adriane P. Wasko / Banca: Roberto Ferreira Artoni / Banca: Sanae kasahara / Banca: Débora Diniz Bezerra / Banca: Orlando Moreira Flho / Doutor