Name: Stefanie Barbosa Potkul Soares
Type: MSc dissertation
Publication date: 04/03/2020

Namesort descending Role
Gustavo Rocha Leite Advisor *

Examining board:

Namesort descending Role
Albert David Ditchfield Internal Examiner *
Ana Carolina Loss Rodrigues External Alternate *
Gustavo Rocha Leite Advisor *

Summary: Chagas disease is considered one of the negleted
tropical diseases of Latin America and its etiological agent is
Trypanosoma cruzi, transmitted by hematophagous bugs, known as
kissing bugs, which belong to the subfamily Triatominae. Within
this dubfamily, there is Panstrongylus megistus, one of the main
vectors of Chagas disease in Brazil. Its epidemiological
importance for Chagas disease is due to its high domiciliation
capacity, commonly found in domestic environments. However, its
domiciliation capacity is different between regions, because in
some areas, this species is considered sylvatic. One of the
possibilities to explain this fact is phylogeography, which is
the study of the processes that influence geographical
distribution of genealogical lineages. Thereby, based on the
phylogeographical patterns of Panstrongylus megistus, this thesis
aims to correlate the different domiciliation capacities of P.
megistus populations. The phylogeographyc analyses was based on
fragments of the mitochondrial gene Cytochrome b (Cytb) and
ribosomal DNA intergenic region (rDNA), comprising complete
internal transcribed spacer (ITS)-1, 5.8S, and ITS-2 sequences.
16 sequences of cytb and 26 sequences of rDNA, from different
populations, were analysed. All the sequences were obtained from
GenBank. Phylogenetic analyses of Bayesian Inference, haplotype
diversity, haplotype network, AMOVA, Fst analysis and Mantel test
were performed. The analyses showed poor genetic structure
associated to geographical distribution of the populations.
Besides, the analyses showed poor diversity and genetic variance
between populations, which suggests a recent population expansion
from na ancestral population, originated in the Atlantic Forest.
Active and passive dispersion explains the specie`s wide
geographical distribution in Brazil, which led some populations
to spread to regions with different environmental conditions.
Thereby, some populations found in the domiciles, favourable
microclimatic conditions and food source, which favoured the
adaptation of these populations to the domiciles, becoming
isolated from other sylvatic populations. Deforastation caused by
human activities has also played na import role on the
domiciliation of some populations, because of the destruction of
natural ecotopes and reduction of food sources. Future research
with bigger number of populations analysed and molecular markers
can present more complete and resolved information regarding
phylogeographical patterns of P. megistus, which will help the
Chagas disease vector surveillance program.

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