Revisiting the Homoploid Hybrid Speciation Process of the Triatoma brasiliensis macromelasoma Galvão, 1956 (Hemiptera, Triatominae) Using Cytogenetic and Molecular Markers

Abstract

Triatomines are vectors of Trypanosoma cruzi, the etiologic agent of Chagas disease. Although the evolutionary process in triatomine is considered as disruptive, cryptic speciation and homoploid hybridization also are possible modes of speciation. Several analyses suggested Triatoma brasiliensis macromelasoma as a product of hybridization between T. brasiliensis and Triatoma juazeirensis. Thus, we analyzed genetic characteristics (chromosomal analysis, genetic distance for the mitochondrial ND1 gene, and the pattern of bands of internal transcribed spacer [ITS]-1) of these species, with emphasis on the phenomenon of homoploid hybridization. All species showed the same cytogenetic characteristics, low genetic distance for ND1 gene, and the same pattern of ITS-1 bands. We consider that these genetic characteristics, together with the large chromatic polymorphism and the viability of experimental crosses possibly are due to the processes of introgression that these species suffered during the process of homoploid hybridization.

Revisiting the Hybridization Processes in the Triatoma brasiliensis Complex (Hemiptera, Triatominae): Reproductive Isolation between Triatoma petrocchiae and T. b. brasiliensis and T. lenti

“…The reproductive barrier that possibly prevents hybrids between other species of the T. brasiliensis complex is based on post-zygotic reproductive isolation due to hybrid collapse (as noted by Mendonça et al [30] and Alevi et al [31]). It was believed that T. melanica was the most differentiated form of the complex [37]; however, according to the results of experimental crosses and the high genetic distance observed between T. petrocchiae and members of the T. brasiliensis complex [46], the most differentiated species from a genetic point of view is T. petrocchiae.…”

Revisiting the hybridization processes in the Triatoma brasiliensis complex (Hemiptera, Triatominae): Interspecific genomic compatibility point to a possible recent diversification of the species grouped in this monophyletic complex

“…Although T. b. macromelasoma is considered as an incipient species, the low interspecific genetic distance observed between T. b. macromelasoma, T. b. brasiliensis and T. juazeirensis [69] together with the production capacity of experimental hybrids (Table 2), point to the possibility of natural hybridization events followed by introgression during the evolution of these taxa [69] (which highlights the need for attention of the vector programs with T. juazeirensismainly in view of the recent catches of this species infected with T. cruzi in human dwellings [73]-(since genes associated with the high vector capacity of T. b. brasiliensis can be fixed in this species by introgression) and with its possible hybrids (that thus the hybrids resulting from the cross between T. sherlocki and T. juazeirensis [33] can present higher fitness than their parents).…”

“…All species and subspecies of the T. brasiliensis complex share the same chromosomal characteristics [15,28,[34][35][36][37][38]69]. Costa et al [70] suggested that T. b. macromelasoma resulted from the natural crossing between T. b. brasiliensis and T. juazeirensis by the phenomenon of homoploidal hybridization.…”