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  • 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.
1

Distribuição da variabilidade genética e fluxo de pólen em subpopulações de Annona crassiflora Mart. (Annonaceae) / Distribution of genetic variability and pollen flow in subpopulations of Annona crassiflora Mart. (Annonaceae)

Almeida Júnior , Edivaldo Barbosa de 21 December 2015 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-09T13:51:21Z No. of bitstreams: 2 Tese - Edivaldo Barbosa de Almeida Júnior - 2015.pdf: 11899635 bytes, checksum: 81eb843ad44f05464a9ded05612db917 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-09T13:51:52Z (GMT) No. of bitstreams: 2 Tese - Edivaldo Barbosa de Almeida Júnior - 2015.pdf: 11899635 bytes, checksum: 81eb843ad44f05464a9ded05612db917 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-09-09T13:51:52Z (GMT). No. of bitstreams: 2 Tese - Edivaldo Barbosa de Almeida Júnior - 2015.pdf: 11899635 bytes, checksum: 81eb843ad44f05464a9ded05612db917 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-12-21 / The Annona crassiflora Mart. species (Annonaceae) is a fruit plant native from Cerrado, widely distributed throughout the biome. The goal here was evaluate the spatial distribution of genetic variability in natural subpopulations of the species, geographically, and relate the genetic diversity levels with climatic and landscape profile, furthermore the pollen dispersal within a subpopulation. We used here six pair of microsatellite primers. To evaluate thedistribution of genetic variability we sampled 25 natural subpopulations, 30.6 plants per subpopulation, on average. We estimate the genetic diversity (He), allelic richness (Ar), fixation index (f), genetic structure, using coancestry coefficient (θ) and inbreeding coefficient of overall population (F). The spatial pattern the genetic variability was evaluated by Mantel test, Moran's I index and linear regression of genetic parameter with two spatial dimensions (latitude and longitude). We correlate He, Ar and f with climate suitability and the percentage of Cerrado vegetation around subpopulations. Furthermore we evaluated the pollen dispersal by paternity analysis, using 572 plants, including 460 seeds, 20 mother plants and 92 pollen donors candidate, within a natural subpopulation. The outcrossing rates were also evaluated in maternal families using the mixed mating model. The outcrossing rates indicate mating system with prevalence of allogamy. The assignment of paternity indicated that gene flow mainly occurs in short distances, until 360 meters, in the subpopulation evaluated. The 25 subpopulations have moderate genetic diversity levels and strong genetic structure. We found inbreeding due to the subdivision, but not in mating within subpopulations. The demes belongs to two consistent groups with genetic discontinuity between the northwest and southeast subpopulations distribution. The genetic diversity and allelic richness showed strong relationship with longitude, suggesting a range expansion in the southeastern direction. We noted that spatial distribution of genetic diversity and allelic richness are related to suitability at the last glacial maximum, by an indirect effect of geographical distances, whereas no relationship was observed regarding present suitability. The percentage of cover natural vegetation, in turn not explain the spatial distribution of genetic diversity, allelic richness and inbreeding coefficient. / A espécie Annona crassiflora Mart. (Annonaceae) é uma planta frutífera nativa do Cerrado, amplamente distribuída ao longo do Bioma. O objetivo do trabalho foi avaliar a distribuição espacial da variabilidade genética em subpopulações naturais da espécie, em um contexto geográfico e relacionar os níveis de diversidade observados com variáveis climáticas e da paisagem, além da distância de dispersão de pólen em escala local, em uma subpopulação natural. No presente estudo foram empregados seis pares de iniciadores microssatélites. Para avaliar a distribuição da variabilidade genética foram amostradas 25 subpopulações naturais, em média 30,6 plantas por subpopulação. Foram estimados os níveis de diversidade genética (He), riqueza alélica (Ar), índice de fixação intrapopulacional (f), estrutura genética, por meio do coeficiente de coancestria (θ) e coeficiente de endogamia da população total (F). O padrão espacial da variabilidade genética foi avaliado por meio do Teste de Mantel, I de Moran e regressão linear dos parâmetros genéticos com as duas dimensões espaciais (latitude e longitude). As estimativas de He, Ar e f foram relacionadas com métricas de adequabilidade climática e com a porcentagem de remanescentes de vegetação do Cerrado. A dispersão de pólen foi avaliada por meio de análise de atribuição de paternidade usando 572 plantas, que incluem 460 semente, 20 plantas matrizes e 92 candidatos a doadores de pólen, em uma subpopulação natural da espécie. As taxas de fecundação cruzada também foram avaliadas, nas famílias maternas, usando o modelo misto de reprodução. As taxas de cruzamento indicam sistema reprodutivo com prevalência de alogamia. A atribuição de paternidade indicou que o fluxo gênico ocorre, prioritariamente, em curtas distâncias, em até 360 metros, na subpopulação avaliada. As 25 subpopulações apresentam níveis elevados de diversidade e forte estruturação genética. Há endogamia devido à subdivisão, mas não em relação ao sistema de cruzamento. Os demes formaram dois grupos consistentes, com descontinuidade genética entre as subpopulações do noroeste e sudeste da distribuição. A diversidade genética e a riqueza alélica mostraram forte relação com a longitude, sugerindo uma expansão da distribuição na direção sudeste. Foi observado que a distribuição espacial da diversidade genética e riqueza alélica estão relacionadas com a adequabilidade climática no último máximo glacial, por um efeito indireto do espaço geográfico, enquanto que nenhuma relação foi observada com a adequabilidade no presente. A porcentagem de remanescentes da vegetação natural, por sua vez não explicou a distribuição espacial da diversidade genética, riqueza alélica e coeficiente de endogamia.
2

Landscape genetics of Alnus glutinosa across contrasting spatial scales in a natural river system

Flint, Gillian F. January 2015 (has links)
The genetic diversity and genetic structure of populations, and the processes shaping gene flow within and between populations, are influenced by the landscapes they occur within. Within terrestrial landscapes, rivers and their riparian habitat are among the most dynamic, diverse and complex of landscapes and their linear structure appears as an interlinking feature across large landscapes. This thesis took a landscape genetics approach to examine the influence of river landscape features on Alnus glutinosa populations, a widespread keystone tree species of European riparian ecosystems. By accounting for the differing dispersal mechanisms of A. glutinosa (wind and water), landscape effects on seed- and pollen-mediated gene flow, genetic diversity, demographic and genetic structure were identified at different spatial scales of a large UK river catchment. Widespread gene flow within and between A. glutinosa populations was identified with no apparent limitation of wind-mediated pollen dispersal. Hydrochorous dispersal of seed between populations was evident, and found to increase genetic connectivity between riparian populations; however an isolation by distance effect was identified between populations located further apart from each other. No pattern of genetic diversity was found, with high levels of genetic diversity identified at all spatial and temporal scales. At the river-catchment scale no genetic clustering was observed, either within or between the six rivers studied. Demographic structuring within A. glutinosa populations was evident, and correlated with distance from the main river channel. Interactions between seed dispersal, hydrological disturbance, colonisation, and historical influences are discussed in relation to fine-scale spatial genetic structure between A. glutinosa sapling and adult generations. Central to the landscape genetics approach taken in this thesis was the incorporation of key A. glutinosa life history attributes. By incorporating gene flow analyses, species ecology and landscape features, the research presented here furthers our understanding of riverine landscape influences on their riparian populations at different spatial scales and can be used to inform management principles.

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