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Phylogenetic and Phylogeographic Studies of Panstrongylus sp., Vectors of Chagas Disease in Loja and Manabí Provinces, Ecuador

Sempertegui-Sosa, Carolina
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1343799373

Abstract Details

2012, Doctor of Philosophy (PhD), Ohio University, Molecular and Cellular Biology (Arts and Sciences).
The species Panstrongylus howardi, P. chinai, and P. rufotuberculatus were found infesting domestic, peri-domestic and sylvatic habitats in the Loja and Manabí provinces in Ecuador, where they are involved in the transmission of Trypanosoma cruzi, the causal agent of Chagas disease. The phylogeny and the phylogeography of these species were studied using the nuclear gene ITS-2 and the mitochondrial gene cytochrome b. Phylogeny was explored using Maximum Likelihood (ML) and Bayesian methods. Phylogeography of each species was studied using genetic diversity indices, neutrality and Mantel's tests. The cytochrome b phylogeny showed P. howardi and P. chinai formed two defined clades, while sequences assigned to P. rufotuberculatus were scattered within both clades. The sequences within the two clades diverged from 0% to 3.1%, and between clades from 4.3% to 8.3%, suggesting that P. chinai and P. howardi are different species, whose divergence might have been assisted by human colonization of the regions. Contrary to the cytochrome b data, ITS-2 recovered P. rufotuberculatus genotypes within a single clade, with little divergence among haplotypes within the clade (0%-1%). Panstrongylus howardi and P. chinai were intermixed in a second clade with divergences among haplotypes ranging from 0% to 2.2%. The divergence between the P. rufotuberculatus and P. howardi/chinai clades was substantial (11.7%-18.1%), clearly distinguishing P. rufotuberculatus as a distinct species. The discrepancies between the phylogenies of these genes strongly suggest introgression between P. rufotuberculatus and the other two species. In addition, the genetic, geographic, morphologic, and biologic characteristics of P. chinai and P. howardi and their haplotypes suggest that these correspond to two evolutionary units. The phylogeographic results showed no genetic structure among populations of P. howardi from the Manabí province. Rather, a recent population expansion event is suggested by neutrality tests. Positive isolation-by-distance among populations located beyond 10 km was found. Because P. howardi has been found in sylvatic and domestic/peri-domestic habitats, this information suggests that P. howardi re-infests habitats after other species of triatomines have been eliminated by the application of insecticide sprays. In Loja, P. chinai showed no intra-specific structure or population expansion. However, a degree of isolation-by-distance was detected, suggesting limited dispersal. Panstrongylus rufotuberculatus lacked both genetic structure and isolation-by-distance, suggesting more widespread dispersal between the Loja and Manabí provinces. Such findings suggest that dispersal of the bugs from one province to another might be human assisted. Passive transport of bugs hitchhiking on human clothes and domestic animals has been reported. Discordant demographic inferences between ITS-2 and cytochrome b suggests sex-biased dispersal within Panstrongylus.
Mario Grijalva, PhD (Advisor)
Edwin Rowland, PhD (Committee Member)
Kenneth Goodrum, PhD (Committee Member)
Sarah Wyatt, PhD (Committee Member)
Shawn Kuchta, PhD (Committee Member)
172 p.
Molecular Biology
Panstrongylus; howardi; rufotuberculatus; chinai; Ecuador; triatomines; phylogenetic; phylogeographic

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Citations

  • Sempertegui-Sosa, C. (2012). Phylogenetic and Phylogeographic Studies of Panstrongylus sp., Vectors of Chagas Disease in Loja and Manabí Provinces, Ecuador [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1343799373

    APA Style (7th edition)

  • Sempertegui-Sosa, Carolina. Phylogenetic and Phylogeographic Studies of Panstrongylus sp., Vectors of Chagas Disease in Loja and Manabí Provinces, Ecuador. 2012. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1343799373.

    MLA Style (8th edition)

  • Sempertegui-Sosa, Carolina. "Phylogenetic and Phylogeographic Studies of Panstrongylus sp., Vectors of Chagas Disease in Loja and Manabí Provinces, Ecuador." Doctoral dissertation, Ohio University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1343799373

    Chicago Manual of Style (17th edition)

ohiou1343799373
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© 2012, all rights reserved.
This open access ETD is published by Ohio University and OhioLINK.