Triatoma sordida is one of the main species with vectorial competence for the transmission of Chagas' disease in Brazil. Several studies indicate polymorphism in T. sordida, which led to the suggestion of the phenomenon of cryptic speciation in this species. Cytogenetic studies with C-Banding and Fluorescent In Situ Hybridization (FISH) demonstrated the presence of three cytotypes, possibly representing different taxa: cytotype I, termed T. sordida sensu stricto, with heterochromatin in all autosomes and 45S rDNA probe in the chromosome X, cytotype II, designated as T. sordida Argentina, with absence of heterochromatin in the autosomes and FISH labeling on sex chromosomes X and Y and cytotype III, designated as T. sordida La Paz, with heterochromatin in all autosomes and marking in a pair of autosomes. Taking into account that the accomplishment of experimental crosses can help in different aspects, such as the understanding of taxonomy, systematics and isolation mechanisms that limit gene flow, as well as the possibility of evaluating the role of natural hybridization in the generation of new genetic variants, the present project aims to analyze the possible barriers of reproductive isolation (pre- or post-zygotic) present between the three cytotypes of T. sordida, by means of experimental crosses and analysis of the resulting hybrids up to the second generation (F2), with emphasis on the analysis of the evolutionary dynamics of the experimental crosses, as well as the analysis of the reproductive viability of the hybrids (spermatogenesis and morphology of male and female gonads). These results will allow elucidating evolutionary and taxonomic questions about T. sordida and the process of cryptic speciation.
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