Evolutionary History of Assassin Bugs (Insecta: Hemiptera: Reduviidae): Insights from Divergence Dating and Ancestral State Reconstruction

Abstract

Assassin bugs are one of the most successful clades of predatory animals based on their species numbers (∼6,800 spp.) and wide distribution in terrestrial ecosystems. Various novel prey capture strategies and remarkable prey specializations contribute to their appeal as a model to study evolutionary pathways involved in predation. Here, we reconstruct the most comprehensive reduviid phylogeny (178 taxa, 18 subfamilies) to date based on molecular data (5 markers). This phylogeny tests current hypotheses on reduviid relationships emphasizing the polyphyletic Reduviinae and the blood-feeding, disease-vectoring Triatominae, and allows us, for the first time in assassin bugs, to reconstruct ancestral states of prey associations and microhabitats. Using a fossil-calibrated molecular tree, we estimated divergence times for key events in the evolutionary history of Reduviidae. Our results indicate that the polyphyletic Reduviinae fall into 11–14 separate clades. Triatominae are paraphyletic with respect to the reduviine genus Opisthacidius in the maximum likelihood analyses; this result is in contrast to prior hypotheses that found Triatominae to be monophyletic or polyphyletic and may be due to the more comprehensive taxon and character sampling in this study. The evolution of blood-feeding may thus have occurred once or twice independently among predatory assassin bugs. All prey specialists evolved from generalist ancestors, with multiple evolutionary origins of termite and ant specializations. A bark-associated life style on tree trunks is ancestral for most of the lineages of Higher Reduviidae; living on foliage has evolved at least six times independently. Reduviidae originated in the Middle Jurassic (178 Ma), but significant lineage diversification only began in the Late Cretaceous (97 Ma). The integration of molecular phylogenetics with fossil and life history data as presented in this paper provides insights into the evolutionary history of reduviids and clears the way for in-depth evolutionary hypothesis testing in one of the most speciose clades of predators.

Chromosomal divergence and evolutionary inferences in Rhodniini based on the chromosomal location of ribosomal genes

“…In the Triatomini tribe, or within the genus Triatoma, the ribosomal genes showed four different chromosomal positions, including autosomes bearing 45S rDNA ). The Rhodniini tribe showed far less variability (rDNA loci restricted to the sex chromosomes), which might reflect their monophyletic origin, in contrast to the putative polyphyletic origin of the genus Triatoma (Hypsa et al 2002, Hwang & Weirauch 2012. However, the Rhodniini variation in the ribosomal cluster position occurred despite their karyotype homogeneity, reflecting a genome dynamic that is not revealed by other chromosome traits.…”

“…The Rhodniini tribe is the second largest and includes two genera: Rhodnius (18 species) and Psammolestes (3 species). Although the phylogenetic origin of many triatomine tribes and genera remains problematic (Hwang & Weirauch 2012), the Rhodniini tribe is considered monophyletic, comprising two groups, namely the robustus and pictipes lineages, with the Psammolestes genus integrating the robustus lineage (Monteiro et al 2000(Monteiro et al , 2002. Rhodniini species display different degrees of synanthropic behaviour from sylvatic to highly domestic (Abad-Franch et al 2009).…”

Description of the diploid chromosome set of Triatoma pintodiasi (Hemiptera, Triatominae)

“…Triatomines are also of biological interest because their cells have several peculiarities in comparison to cells of other eukaryotes, such as holocentric chromosomes (Panzera et al, 1996), inverted meiosis for sex chromosomes (Gómez-Palacio et al, 2008), and persistence of nucleolar material during meiosis (Tartarotti and Azeredo-Oliveira, 1999;Alevi et al, 2014a). In addition, triatomines are of evolutionary interest because their origins (monophyletic or polyphyletic) have not been conclusively determined (Tartarotti et al, 2006;Hwang and Weirauch, 2012).…”

Uncovering hidden biodiversity: phylogeny and taxonomy of Physoderinae (Reduviidae, Heteroptera), with emphasis on Physoderes Westwood in the Oriental and Australasian regions

“…These hypotheses were either not based on cladistic analyses (Miller 1954;Lent & Wygodzinsky 1979) or hampered by inadequate taxon sampling (Weirauch 2008;Weirauch & Munro 2009). A recent molecular phylogenetic analysis with more comprehensive sampling of Reduviinae (but lacking Aradomorpha) found Physoderinae to be closely related to the Neotropical reduviine genera Microlestria Stål, 1872 and Nalata Stål, 1860 (Hwang & Weirauch 2012). To date, relationships among genera and species of Physoderinae have not been investigated using cladistic methods: molecular data are available for less than a handful of species and morphological characters have not been coded and analyzed across the group.…”