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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

Multivariate Analyses of Amphibian and Reptilian Distribution in Texas

Ward, Rocky 08 1900 (has links)
Presence-absence data for amphibians, chelonians, saurians, ophidians, and the terrestrial and aquatic ecological guilds of reptilians were analyzed using multivariate analyses. Geographically consistant distributional patterns were found for all faunal groupings. The correspondence between analyses of the different taxa and guilds was not perfect, but similarities were found. All analyses agreed on the presence of a distinctive region in east Texas. Most analyses also agreed on the presence of distinctive regions in south Texas, the Trans-Pecos, the Edwards Plateau, and north-west Texas. There is strong correspondence between interpretations of the analyses based on the amphibian, saurian, ophidian, and terrestrial reptilian distributions, and the biotic provinces produced by earlier, subjective analyses. The Edwards Plateau and a region on the western periphery of east Texas were found to be transitional between other, more faunally distinctive areas for most fauna! groups. Detailed examination of these regions suggested they are best described as clinal in nature. The environmental variables which were most effective in explaining patterns in the distribution of the various taxa and guilds were related to precipitation. However, variations in temperature and physiography were also important predictors of distribution for several of the groups. The distributions of soil and vegetation associations were also found to be related to amphibian and reptilian distribution.
2

Variação no canto de anúncio de Dendropsophus cruzi (Pombal & Bastos,1998) (Anura: Hylidae) / Variation in advertisement call of Dendropsophus cruzi (Pombal & Bastos, 1998) (Anura: Hylidae)

Tessarolo, Geiziane 25 February 2010 (has links)
Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2014-11-28T19:04:53Z No. of bitstreams: 2 Dissertação - Geiziane Tessarolo - 2010.pdf: 902545 bytes, checksum: a4abaf0af5b81e44d951ca860f70998b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-12-04T14:13:52Z (GMT) No. of bitstreams: 2 Dissertação - Geiziane Tessarolo - 2010.pdf: 902545 bytes, checksum: a4abaf0af5b81e44d951ca860f70998b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-12-04T14:13:52Z (GMT). No. of bitstreams: 2 Dissertação - Geiziane Tessarolo - 2010.pdf: 902545 bytes, checksum: a4abaf0af5b81e44d951ca860f70998b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2010-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The advertisement call of anurans contains spectral and temporal information important for specific recognition, beside relevance in social organization and attraction of females. The variation in features call has been received attention because their importance in breeding behavior, and implications for the recognition of conespecifics in multiple levels of social organization. The objective of this study is to investigate patterns of variability in the acoustics properties of the advertisement call of Dendropsophus cruzi in different levels: individual, population and specific, in ten populations of state of Goiás. The following acoustic variables were analyzed: call repetition rate, duration of call, number of pulses, duration of pulse and dominant frequency. The acoustics parameters weret influenced as for temperature as for rostrumcloacal length (CRC), and presented different variability coefficients, within-male and among-male being the variability among-male greater than the variability within-male. The dominant frequency is the property of greater potential for use in the specific recognition and also is the characteristic that best discriminates populations. The geographic distance did not predict the differences found in the call. However, geographic cline patterns was found for duration of call, call repetition rate and CRC. The differences among populations can be due to local selective pressures as environmental and social structure of the chorus. The decreases of CRC to the north reflect the gradual change in the temperature in the same sense, influencing the development and growth rates, with smaller individuals. On the other hand, the increase of the temporal characters of call occur for increase the loss attractiveness caused by the high dominant frequency imposed by the smallest size of the body. / O canto de anúncio contém informações espectrais e temporais importantes para o reconhecimento específico, além de sua relevância na organização social e atração sexual de fêmeas. A variação nas características do canto tem recebido bastante atenção devido sua importância no comportamento de acasalamento e suas implicações para o reconhecimento de coespecíficos em múltiplos níveis de organização social. Assim o objetivo deste estudo é investigar padrões de variabilidade nos parâmetros acústicos do canto de anúncio de Dendropsophus cruzi em nível individual, populacional e específico, em dez populações do estado de Goiás. As seguintes variáveis acústicas foram analisadas: taxa de repetição, duração do canto, número de pulsos, duração do pulso e frequência dominante. Os parâmetros acústicos foram influenciados tanto pela temperatura como pelo comprimento rostro-cloacal (CRC), e apresentaram diferentes coeficientes de variação, sendo que o CVinter-individual foi maior que o CVintraindividual. A freqüência dominante é a propriedade de maior potencial para ser usada no reconhecimento específico e também é a característica que melhor discrimina as populações. A distância geográfica entre as populações não foi preditora para as diferenças encontradas no canto. Entretanto padrões geográficos clinais foram encontrados para duração do canto, freqüência dominante, taxa de repetição e CRC. As diferenças entre as populações podem ser devidas a pressões seletivas locais tanto ambientais como de estrutura social do coro. A diminuição do CRC ao norte reflete a mudança gradual de temperatura que ocorre nesse sentido, influenciando as taxas de desenvolvimento e crescimento, com indivíduos menores. Por outro lado o aumento das características temporais do canto ocorre para aumentar a atratividade perdida pelas altas freqüências dominantes impostas pelo menor tamanho do corpo.

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