The thesis aims at clarifying the taxonomic difficulties in the Tortula muralis complex. For the first time, the group was studied by means of morphometric analysis, ploidy level assessment by flow cytometry, and molecular analysis based on sequencing of ITS region of nuclear ribosomal DNA. Morphometric and cytometric studies found only two well distinguished groups within the complex. These groups corresponded to the markedly variable species T. muralis and to the rather uniform species T. lingulata. Variability in ITS sequences suggested extensive gene flow among some of traditional morphologically defined taxa of the complex. Multiple polytopic autopolyploid origin of polyploids was revealed in some taxa. Changes in taxonomic conception of T. muralis complex were proposed in order to reflect structure of morphological, karyological, and DNA variability in the group. Natural hybridization is probably an important evolutionary mechanism that generated morphological diversity and taxonomic complexity in the mosses of T. muralis complex.

Made available in DSpace on 2015-03-26T13:42:15Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1200564 bytes, checksum: 7a0f61b430c00f9ecb6c3820735aa8e0 (MD5) Previous issue date: 2010-02-24 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The investigation of intra-individual variation of the rDNA cistron ITS in Carapichea ipecacuanha was made from direct sequencing of 26 individuals and from sequencing of 240 clones, representing another 51 individuals. The secondary structures of 5.8S and ITS2 regions show the typical configurations present in angiosperms respectively for 20 and 48 haplotypes. The comparison with the conserved motifs in angiosperms and the secondary structures obtained for the 5.8S region, the most reliable markers of functional sequences in C. ipecacuanha, allowed the identification of 13 pseudogenes among 26 haplotypes of 5.8S. The analysis of the secondary structure of ITS2 added one haplotype to the set of pseudogenes. The loss of functionality in some haplotypes has occurred prior to the others copies due to the accumulation of a larger number of substitutions and the formation of groups of pseudogenes that belong to distinct populations. / A investigação da variação intra-individual do cistron de rDNA ITS em Carapichea ipecacuanha foi realizada a partir de seqüenciamento direto de fragmentos de PCR de 26 indivíduos e do seqüenciamento de 240 clones, representando outros 51 indivíduos. As estruturas secundárias das regiões 5.8S e ITS2 apresentam as configurações típicas presentes em angiospermas respectivamente em 20 e 48 haplótipos encontrados. A comparação com os motivos conservados em angiospermas e as estruturas secundárias obtidas para a região 5.8S, indicadores mais confiáveis da funcionalidade das seqüências em C. ipecacuanha, permitiram a identificação de 13 pseudogenes entre os 26 haplótipos de 5.8S encontrados. A análise da estrutura secundária do ITS2 adicionou um haplótipo ao conjunto de pseudogenes. A perda de funcionalidade em alguns haplótipos deve ser mais antiga do que em outros em razão do acúmulo de maior número de substituições e da formação de grupos de pseudogenes pertencentes a populações distintas.