Towards a phylogenetic approach to the composition of species complexes in the North and Central American Triatoma, vectors of Chagas disease

Abstract

Phylogenetic relationships of insect vectors of parasitic diseases are important for understanding the evolution of epidemiologically relevant traits, and may be useful in vector control. The subfamily Triatominae (Hemiptera:Reduviidae) includes ~140 extant species arranged in five tribes comprised of 15 genera. The genus Triatoma is the most species-rich and contains important vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Triatoma species were grouped into complexes originally by morphology and more recently with the addition of information from molecular phylogenetics (the four-complex hypothesis); however, without a strict adherence to monophyly. To date, the validity of proposed species complexes has not been tested by statistical tests of topology. The goal of this study was to clarify the systematics of 19 Triatoma species from North and Central America. We inferred their evolutionary relatedness using two independent data sets: the complete nuclear Internal Transcribed Spacer-2 ribosomal DNA (ITS-2 rDNA) and head morphometrics. In addition, we used the Shimodaira-Hasegawa statistical test of topology to assess the fit of the data to a set of competing systematic hypotheses (topologies). An unconstrained topology inferred from the ITS-2 data was compared to topologies constrained based on the four-complex hypothesis or one inferred from our morphometry results. The unconstrained topology represents a statistically significant better fit of the molecular data than either the four-complex or the morphometric topology. We propose an update to the composition of species complexes in the North and Central American Triatoma, based on a phylogeny inferred from ITS-2 as a first step towards updating the phylogeny of the complexes based on monophyly and statistical tests of topologies.

Biological parameters of interbreeding subspecies ofMeccus phyllosomus(Hemiptera: Reduviidae: Triatominae) in western Mexico

“…Various studies have established that M. p. longipennis, M. p. picturatus, and M. p. pallidipennis subspecies are almost genetically identical (Martínez et al ., 2005, 2006; Bargues et al ., 2008, Martínez-Hernández et al ., 2010; Espinoza et al , 2013), and pairwise comparisons of ITS-2 sequences indicated identical M. p. longipennis (= T. longipennis ) and M. p. picturatus (= T. picturata ) sequences and only two nucleotide differences between M. p. longipennis, M. p. picturatus, and M. p. pallidipennis (= T. longipennis ). In contrast, other studies of the biological parameters and morphological characteristics have shown important differences among the three subspecies (Martínez-Hernández et al , 2010, Martínez-Ibarra et al , 2012, 2013, 2015 d ; De la Rúa et al ., 2014; Rivas et al ., 2014). Our results are consistent with those last cited studies, supporting the proposal that the three subspecies are different enough from one another to be considered subspecies, not a single one.…”

Hypothesis testing clarifies the systematics of the main Central American Chagas disease vector, Triatoma dimidiata (Latreille, 1811), across its geographic range

“…The use of a single marker (or concatenated data from the same mitochondrial genome when two markers were used) on each individual has been particularly problematic. In the general field of systematics, one statistical method for comparing phylogenetic trees, the Shimodaira-Hasegawa Test (Shimodaira and Hasegawa, 1999), has been used extensively (>2,700 citations in ISI Web of Knowledge, May 2016) including several vectors and pathogens (de la Rua et al, 2014; Dyer et al, 2011; Gaunt and Miles, 2002; Hamilton et al, 2007; Outlaw and Ricklefs, 2011). …”

A biogeographic–ecological approach to disentangle reticulate evolution in the Triatoma phyllosoma species group (Heteroptera: Triatominae), vectors of Chagas disease

“…While nuclear gene trees of species within the T. phyllosoma group have low resolution, they are often regarded as broadly consistent with a priori expectations about species relationships (de la Rúa et al, 2014;Marcilla et al, 2001;Martínez et al, 2006;Mas-Coma & Bargues, 2009). Conversely, the better-resolved mitochondrial trees are regarded as less reliable because of striking mito-nuclear genetree incongruences.…”