A fim de avaliar a diversidade genética, morfológica e filogeografia de tripanossomas de leptodactilídeos, analisamos diversos isolados encontrados em amostras de sangue e fígados obtidos no Brasil (Amazônia, Caatinga, Cerrado, Mata Atlântica e Pantanal), na Colômbia e na Venezuela. Inferências filogenéticas baseadas em marcadores moleculares (V7V8 SSUrDNA e gGAPDH) demonstraram uma complexa associação entre clados, biomas e hospedeiros vertebrados. Nossos resultados corroboram a monofilia dos trypanossomas de anuros e sugerem a existência de, ao menos, seis clados (An01-06) nesse grupo com 12 candidatos a novas espécies. O clado An01 compreende tripanossomas de leptodactilídeos e hilídeos de todos os biomas. Os clados An02, An05 e An06 são formados, predominantemente, por tripanossomas de leptodactlídeos de diferentes biomas brasileiros, da Colômbia e da Venezuela. O clado An03 é formado por tripanossomas de leptodactilídeos, bufonídeos e flebotomíneos, todos do bioma amazônico. O clado An04 agrupa apenas tripanossoma exóticos da América do Norte, África e Europa. / Aiming to investigate the genetic diversity, the morphology and the phylogeny of leptodactylid trypanosomes, we analyzed a number of trypanosomes from blood and liver samples from Brazil (Amazonia, Caatinga, Cerrado, Atlantic Forest and Pantanal), Colombia and Venezuela. Phylogenetic analyses based on molecular markers (V7V8 SSUrDNA and gGAPDH) demonstrated a complex association between clades, biomes and vertebrate hosts. Our results corroborated the monophyly of anuran trypanosomes and suggested the existence of, at least, six clades (An01-06) inside the anuran clade with 12 candidate new species. Clade An01 groups trypanosomes from leptodactylids and hylids collected in all biomes. Clades An02, An05 and An06 are composed, mostly, by leptodactylid trypanosomes from several Brazilian biomes, Colombia and Venezuela. Clade An03 aggregates parasites from leptodactylids, bufonids and phlebotomines from Amazonia. Clade An04 groups only exotic trypanosome species from North America, Africa and Europe.

Most methods for analysis of genomic data work with symbolic sequences. Numerically represented genomic sequences can be analyzed by signal processing methods. A new method of numerical representation of DNA sequences, nucleotide density vectors, is proposed in this thesis. Usability of this method for purposes of molecular species identification is tested on DNA barcoding sequences. DNA barcoding is modern and popular methodology based on comparison of short mitochondrial DNA sequences. Beside species identification by proposed method based on nucleotide density vectors, higher taxa rank identification (e.g. families) was also tested. Furthermore, dendrograms were constructed from standardly used evolutionary distances and distances between nucleotide density vectors and the dendrograms were compared.

A subset of 199 Melissotarsus insularis and 130 Diaspididae specimens were analyzed to 1) determine the species status of M. insularis and 2) to explore the relative intimacy of the relationship between M. insularis and Diaspididae. An analysis of molecular variance and the observed lack of association between clades and distinct habitats on the M. insularis phylogeny suggested that while M. insularis exhibits isolation by distance, it does not apparently diversify by habitat. When cryptic COI pseudogenes were accounted for, the majority of the genetic diversity exhibited by M. insularis was limited to a divergence of 3% or less suggesting that M. insularis represents a single, albeit broadly distributed, species. A cophylogenetic reconstruction of the relationship between M. insularis and Diaspididae yielded 14 “cospeciation” events but was not significant unlike reconstructions of host-parasite relationships. Analyses of reduced datasets suggested that incomplete taxon sampling may significantly affect cophylogenetic reconstruction results. / National Science Foundation (grants No. DEB-0072713, DEB-0344731 to BLF and DEB-0842395 to BLF and MAS), a Natural Sciences and Engineering Research Council of Canada Discovery Grant to MAS and a Leaders Opportunity Fund grant from the Canada Foundation for Innovation to MAS