Genetic variation and phylogeography of the Triatoma dimidiata complex evidence a potential center of origin and recent divergence of haplogroups having differential Trypanosoma cruzi and DTU infections

Abstract

The population genetics of Triatoma dimidiata haplogroups was analyzed at landscape and sub-regional scales in Chiapas and regional level across the Mexican Neotropics, and phylogeography of the complex was re-analyzed across its complete geographic range. Two contiguous fragments of the ND4 gene were analyzed due to bias from differential haplogroup specificity using a previously designed sequence. At both landscape (anthropic modification gradient) and regional (demographic, fragmentation, biogeographic, climate) scales, lowest T. dimidiata genetic diversity occurs where there is greatest historical anthropic modification, and where T. cruzi infection prevalence is significantly highest. Trypanosoma cruzi prevalence was significantly higher than expected in haplogroups 1 and 3, while lower than expected in haplogroup 2. There was also a significant difference of DTUI and DTUVI infection frequencies in both haplogroups 1 and 3, while no difference of either in haplogroup 2. All haplogroups from the Mexican Neotropics had moderate to high haplotype diversity, while greatest genetic differentiation was between haplogroups 1 and 3 (above FST = 0.868, p < 0.0001). Divergence of the complex from the MRCA was estimated between 0.97 MYA (95% HPD interval = 0.55–1.53 MYA) and 0.85 MYA (95% HPD interval = 0.42–1.5 MYA) for ND4A and both concatenated fragments, respectively, with primary divergence from the MRCA of haplogroups 2 and 3. Effective population size for Mexican haplogroups 1 and 2 increased between 0.02 and 0.03 MYA. This study supports previous ecological niche evidence for the complex´s origin surrounding the Tehuantepec Isthmus, and provides evidence for recent divergence of three primary dimidiata haplogroups, with differential T. cruzi infection frequency and DTU specificity, important components of vector capacity.

Identifying Chagas disease vectors using Elliptic Fourier Descriptors of body contour: A case for the cryptic dimidiata complex

“…In the case of the head, Bustamante et al [12] consider that an important factor in the variability observed in this region is due to the geographic isolation of the populations of T. dimidiata, which has led to divergent evolution. The haplogroups used in this study mainly have allopatric populations, which could explain the morphometric differences found, although there are areas of sympatry [16]. In turn, differences in the head may have an evolutionary cause related to feeding strategies and growth patterns of this area of the body.…”

“…Phylogenetic studies defined three major haplogroups for Mexico and part of Central America [13], which were recently reaffirmed by Pech-May et al [16]. Although the three haplogroups are completely differentiable by molecular analysis, they have not yet been successfully delimited using morphometric approaches.…”

“…Multiple inter-and intraspecies taxonomic questions have arisen in this group, with species repeatedly included and excluded from different complexes throughout the history of the study of their systematics and taxonomy [9,10,11,12]. The combination of unresolved taxonomic relationships and the detection of cryptic species within this genus highlight the need to address the systematics of this group [13,14,15,16]. The phenomenon of cryptic speciation is common in Triatominae [17,18,19,20] and results in species that are nearly identical morphologically, which often makes identification based only on traditional morphological characters difficult or impossible.…”

“…The Triatoma dimidiata complex represents one of the major vectors of Chagas disease in all of the countries where it is distributed [16,24,25]. It is present in Mexico, all of the countries of Central America, Colombia, Ecuador and Perú [16,26].…”

“…The Triatoma dimidiata complex represents one of the major vectors of Chagas disease in all of the countries where it is distributed [16,24,25]. It is present in Mexico, all of the countries of Central America, Colombia, Ecuador and Perú [16,26]. Throughout its range, it can be found in jungle, peridomestic and domestic habitats, where non-domiciled populations act as sources of reinfestation and participate in the transmission of the parasite to humans [26,27,28,29].…”