Trends in evolution of the Triatomini tribe (Hemiptera, Triatominae): reproductive incompatibility between four species of geniculatus clade

Abstract

Background The geniculatus clade, composed by the rufotuberculatus, lignarius, geniculatus and megistus groups, relates evolutionarily the species of the genus Panstrongylus and Nesotriatoma. Several studies have shown that triatomine hybrids can play an important role in the transmission of Chagas disease. Natural hybrids between species of the geniculatus clade have never been reported to our knowledge. Thus, carrying out experimental crosses between species of the geniculatus clade can help to elucidate the taxonomic issues as well as contribute to the epidemiological knowledge of this group. Methods Experimental crosses were carried out between species of the megistus and lignarius groups to evaluate the reproductive compatibility between them. A phylogenetic reconstruction was also performed with data available in GenBank for the species of the geniculatus clade to show the relationships among the crossed species. Results Phylogenetic analysis grouped the species of the geniculatus clade into four groups, as previously reported. In the interspecific crosses performed there was no hatching of eggs, demonstrating the presence of prezygotic barriers between the crossed species and confirming their specific status. Conclusions In contrast to the other groups of the Triatomini tribe, as well as the Rhodniini, there are prezygotic barriers that prevent the formation of hybrids between species of the megistus and lignarius groups. Thus, the geniculatus clade may represent an important evolutionary model for Triatominae, highlighting the need for further studies with greater sample efforts for this clade (grouping the 17 species of Panstrongylus and the three of Nesotriatoma). Graphical Abstract

Karyotype Evolution in Triatominae (Hemiptera, Reduviidae): The Role of Chromosomal Rearrangements in the Diversification of Chagas Disease Vectors

“…The separation of the ancestors of P. megistus and P. tibiamaculatus has already been related to the formation of a dry corridor between the Atlantic Forest and the Amazon rainforest after the uplift of the Andes, which acted as a vicariant event [ 44 ]. Considering that allopatric species may not develop mechanisms that make hybridization between them unfeasible [ 49 ], the prezygotic isolation observed in experimental crosses between P. megistus and P. tibiamaculatus [also observed between P. megistus and P. lignarius (Walker, 1873)] ( Table 1 ) may be related to the difference in the number of chromosomes [ 32 ]. Thus, the alteration of the karyotype in the ancestors of P. megistus may have contributed to the isolation between these species.…”

“…Recently, experimental crosses between triatomine species with different chromosome numbers were performed, and it was demonstrated that there is prezygotic isolation [ 18 , 32 ]. Based on these observations, the authors suggested karyotypic variation may be an important factor in the reproductive isolation of these insects [ 18 , 32 ]. In Lepidoptera, for example, it has been suggested that in some genera, karyotypic changes may be related to speciation events [ 33 ].…”

Biological aspects of crosses between populations of Triatoma mexicana (Hemiptera: Reduviidae: Triatominae)

“…Prezygotic reproductive barriers, for example, confirmed the generic status of Psammolestes (Ravazi et al 2022). In addition, postzygotic barriers allowed the revalidation of T. bahiensis Sherlock & Serafim (Mendonca et al 2016), describe T. rosai Alevi et al [from specimens of T. sordida (Stål) from Argentina] (Alevi et al 2020), and confirm the specific status of species of Triatoma Laporte (Mendonca et al 2016), Rhodnius Stål (Díaz et al 2014), Psammolestes Bergroth (Ravazi et al 2021), and Panstrongylus Berg (Villacís et al 2020, Reis et al 2022).…”