A história evolutiva de Trypanosoma: elucidando as relações filogenéticas do grupo por meio de distintos métodos e marcadores

Abstract

The present study aims to apply a methodology of sequence-structure analysis to estimate the evolutionary tree of the genus of flagellate parasites Trypanosoma, and to compare inference methods already used in the literature, such as the concatenated analysis between the V7V8 subregion of the SSU 18S rDNA molecular marker and the gGAPDH gene, and the analysis only with the SSU 18S rDNA gene. Through the comparative analyses, it could be seen that the results are in agreement with the previous information generated by the analyses based on data with the 18S rDNA gene, corroborating evolutionary theories and the general branching order of the topologies. Thus, sequencestructure analysis made it possible to access deep phylogenetic relationships among trypanosome species. The new sequence-structure methodology was able to access all previously known subgenera using a single molecular marker (SSU 18S rDNA) with maximum support value. Furthermore, the results of the sequence-structure analysis were more robust than the other analyses, more sensitive to artifacts left by Rogue taxa (id.est. incertae sedis) and to species linked to branch attraction effect. Knowing what the real evolutionary history of these parasites was is an unknown, but the use of tools that offer greater resolving power for phylogenetic relationships may be a way out. Thus, the present study indicates a highly efficient tool for phylogenetic analysis of Trypanosoma. Furthermore, the use of methodologies that allow deep grouping analyses, requiring fewer molecular markers, are of extreme importance.