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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

Pollen Performance and Seedling Vigor in Laboratory and Natural Populations of Clarkia Unguiculata (Onagraceae)

Németh, M. Barbara 08 June 2005 (has links)
No description available.
2

Biologia populacional comparada de duas esp?cies de heliconius (Lepidoptera: Nymphalidae) em um ambiente sazonal de floresta atl?ntica do nordeste brasileiro

Lima, Luciana Lopes Ferreira de 28 August 2009 (has links)
Made available in DSpace on 2014-12-17T14:33:03Z (GMT). No. of bitstreams: 1 LucianaLFL.pdf: 2263314 bytes, checksum: 031f7f356fbeb6a00725098fb2fbe8c6 (MD5) Previous issue date: 2009-08-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Tropical environments often face strong seasonal variations in climate, such as alternate periods of dry and rain, that may often be important influence in the annual X the organisms lives. Here we assess how population dynamics of two butterfly species (Heliconius erato and Heliconius mepomene) respond to environmental and seasonal variations. A mark-release-recapture study carried out in an Atlantic forest reserve, 15 Km from Natal, Rio Grande do Norte, Brazil, for 3 years, during the dry and rainy season, with three visits weekly done. Information such as species, wing lenght, site of capture, pollen load and phenotype (number of spots) (in H. erato only) were noted for each capture. Seasonal variation exists in capture rates of the two species, with great capture rates during the rainy season. Despite finding differences in the mean density of individuals of the two species among the different collection areas, this difference was only significant between floodplain and central areas, and no influence of seasonality was observed in the mean density between the areas. Seasonality in wing size was only observed for H. erato, with larger wings during the rainy season. Females carried larger pollen loads than males both species, but species were similar. Only males differed seasonally, with larger pollen loads during the rainy season. The distribution of the number of wing spots did not vary between the dry and rainy seasons, and the number of spots in males and females was similar. Therefore, we conclude that there was a strong influence of seasonal variation in the population dynamic of the two Heliconius species, as well as in several aspects of their biology / Ambientes tropicais, assim como temperados, costumam se deparar com fortes varia??es sazonais em seus regimes clim?ticos, manifestadas atrav?s de per?odos alternados de seca e chuva, que podem ter pronunciada influ?ncia em diversos aspectos da vida dos organismos que neles habitam. O presente estudo teve como objetivo avaliar como a din?mica populacional de duas esp?cies de borboleta (Heliconius erato e Heliconius melpomene) responde ?s varia??es ambientais sazonais por elas enfrentadas. Um trabalho de marca??o e recaptura das esp?cies foi realizado em uma reserva de mata Atl?ntica localizada cerca de 15 km da cidade de Natal (RN), durante um per?odo de tr?s anos, nos meses mais secos e chuvosos do ano, com tr?s visitas semanais. Informa??es como esp?cie, comprimento alar, local de captura, idade, tamanho da carga pol?nica coletada e fen?tipo (n?mero de manchas na por??o ventral das asas anteriores) em H. erato foram obtidas para cada captura. Observou-se varia??o sazonal nas taxas de captura das duas esp?cies, com maior incid?ncia nos per?odos mais chuvosos, e baixa taxa de recaptura, principalmente nos per?odos mais secos. Apesar de encontrada diferen?a na densidade m?dia de indiv?duos das duas esp?cies entre as diferentes ?reas de coleta, esta foi significativa somente entre as ?reas de v?rzea e central, e n?o foi observada influ?ncia da sazonalidade na densidade m?dia entre as ?reas. O efeito da sazonalidade sobre o comprimento alar somente foi observado para H. erato, com indiv?duos coletados nos per?odos de chuva apresentando tamanhos superiores. F?meas coletaram maiores cargas pol?nicas do que machos nas duas esp?cies, mas n?o houve diferen?a quando comparadas as esp?cies entre si. Quando analisada a influ?ncia sazonal na obten??o de p?len, somente os machos apresentaram diverg?ncias entre as esta??es, com indiv?duos capturados nos per?odos mais chuvosos coletando maiores cargas pol?nicas. Quanto ? varia??o fenot?pica em H. erato, a distribui??o do n?mero de manchas n?o variou entre as esta??es seca e chuvosa, assim como n?o houve diferen?a no n?mero de manchas entre machos e f?meas. Podemos ent?o concluir que houve forte influ?ncia da varia??o sazonal na din?mica populacional das duas esp?cies de Heliconius, bem como em v?rios aspectos de sua biologia

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