Full text
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| Author(s): |
Vagner José Mendonça
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2007-07-26 |
| Examining board members: |
João Aristeu Rosa;
Mara Cristina Pinto;
Maurício Bacci
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| Advisor: | João Aristeu Rosa |
| Abstract | |
Wild triatomines collected by Cerqueira in 1975 in Santo Inácio,BA, Brazil were studied by Papa et al. (2002), who observed morphological differences from other species of the Triatominae, concluding that they represented a new species, named Triatoma sherlocki. Mitochondrial (cytocrome b and 16S) and nuclear (ITS-2 and 28S) gene sequencing of T. sherlocki and T. brasiliensis was carried out with the aim of learning more about the new species and its phylogenetic relationship to the species of the Triatominae subfamily. The sequences ware aligned with the Clustal W application of the BioEdit freeware program and the phylogenetic relationship inferred by estimating distances with the Kimura 2-parameter and p-distance methods of the Neighbor-Joining algorithm in the MEGA 3.1 program and Maximum Parsimony (MP) method of the PAUP 4.1 program. The phylogeny based on the two mitochondrial genes disclosed that T. sherlocki and T. melanica were closely related and that T. brasiliensis was a sister species of the two, with the exception that in for the Parsimony analysis of the 16S gene, T. melanica appeared as a sister species of the clade formed by T. sherlocki and T. brasiliensis. The species Panstrongylus megistus and T. infestans are related to North American species in phylogenetic analyses of the large subunit ribosomal RNA mitochondrial gene (16S) and the amino acid sequences of cytocrome b, respectively. The phylogeny based on the large subunit ribosomal D2 (28S) nuclear gene revealed to a polytomy involving T. sherlocki, T. brasiliensis and T. melanica. This phylogeny was underestimated due to the small number of species present in the tree. This same relationship occurred in the phylogeny of internally transcribed spacer 2 (ITS-2) nuclear gene, in analysis based on Maximum Parsimony. The analysis of distance in this gene revealed proximity between T. sherlocki and T. brasiliensis, with T. melanica as sister species. This phylogeny showed T. maculata, T. brasiliensis and T. infestans to be closely related to North American triatomines. Certain species, such as T. infestans and P. megistus, exhibited more than one topology with different genes, and fusther study is needed to define the phylogenetic positions of these species. The proximity of T. sherlocki to the T. brasiliensis haplotypes, especially with the species T. melanica, may reveal a possible phylogeography originaling from T. brasiliensis ancestors, thus implying derived species (AU) | |