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.
Highlights
Triatoma dimidiata (Latreille, 1811), is one of the broadest distributed triatomine species complexes transmitting Trypanosoma cruzi, the etiological agent of Chagas disease
The question arises whether haplogroups have similar genetic diversity in domestic/modified landscapes, as well as infection characteristics and parasite Discrete Typing Unit (DTU) associations, key components of vector capacity
Triatoma dimidiata was collected from human communities west of the Tehuantepec Isthmus and Chimalapas forest (Nopala county on the Pacific coast, Tuxtepec and Isthmus region of Oaxaca, Veracruz, San Luis Potosı), and from fragmented landscapes east of the Isthmus from northern and coastal counties across Chiapas (Berriozabal, Palenque, Tapachula, Mapastepec and the Soconusco region), and the Yucatan Peninsula
Summary
Triatoma dimidiata (Latreille, 1811), is one of the broadest distributed triatomine species complexes transmitting Trypanosoma cruzi, the etiological agent of Chagas disease. This vector complex is the only one to naturally extend throughout the northern Neotropical realm of North, Central, and South America. The complex is found in a variety of domestic, peri-urban and sylvatic habitats. In the wild, it has been found in a variety of ecotopes eg. Triatoma dimidiata haplogroups (Hg) are all considered primary vectors of Chagas disease south of the Tehuantepec Isthmus [1, 7,8,9,10]. Throughout its geographic distribution, sympatry of at least two of the haplogroups has been reported [5, 8, 16, 18, 33, 34]
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