Phylogeography and demographic history of the Chagas disease vector Rhodnius nasutus (Hemiptera: Reduviidae) in the Brazilian Caatinga biome

Abstract

BackgroundRhodnius nasutus, a vector of the etiological agent Trypanosoma cruzi, is one of the epidemiologically most relevant triatomine species of the Brazilian Caatinga, where it often colonizes rural peridomestic structures such as chicken coops and occasionally invades houses. Historical colonization and determination of its genetic diversity and population structure may provide new information towards the improvement of vector control in the region. In this paper we present thoughtful analyses considering the phylogeography and demographic history of R. nasutus in the Caatinga.Methodology/Principal findingsA total of 157 R. nasutus specimens were collected from Copernicia prunifera palm trees in eight geographic localities within the Brazilian Caatinga biome, sequenced for 595-bp fragment of the mitochondrial cytochrome b gene (cyt b) and genotyped for eight microsatellite loci. Sixteen haplotypes were detected in the cyt b sequences, two of which were shared among different localities. Molecular diversity indices exhibited low diversity levels and a haplotype network revealed low divergence among R. nasutus sequences, with two central haplotypes shared by five of the eight populations analyzed. The demographic model that better represented R. nasutus population dynamics was the exponential growth model. Results of the microsatellite data analyses indicated that the entire population is comprised of four highly differentiated groups, with no obvious contemporary geographic barriers that could explain the population substructure detected. A complex pattern of migration was observed, in which a western Caatinga population seems to be the source of emigrants to the eastern populations.Conclusions/SignificanceR. nasutus that inhabit C. prunifera palms do not comprise a species complex. The species went through a population expansion at 12–10 ka, during the Holocene, which coincides with end of the largest dry season in South America. It colonized the Caatinga in a process that occurred from west to east in the region. R. nasutus is presently facing an important ecological impact caused by the continuous deforestation of C. prunifera palms in northeast Brazil. We hypothesize that this ecological disturbance might contribute to an increase in the events of invasion and colonization of human habitations.

Phylogeography of the Assassin Bug Sphedanolestes impressicollis in East Asia Inferred From Mitochondrial and Nuclear Gene Sequences

“…It adapts to long-distance diffusion and is relatively sensitive to temperature changes, making it an ideal model for the evaluation of phylogeographic patterns and the assessment of the effects of topography and climatic cycles on the demographic history of East Asian reduviids and other indigenous insects [ 22 ]. Since sample collection is difficult, however, very few phylogeographic studies have focused on reduviid species [ 23 , 24 ]. Analyzing the genetic structure of this species helps test hypotheses concerning glacial migration across paleogeographic land bridges and vicariant range segregation caused by inter- and postglacial sea level increases.…”

Under pressure: phenotypic divergence and convergence associated with microhabitat adaptations in Triatominae

“…We reasoned that the broad ecological flexibility of R. ecuadoriensis was likely to correlate with similarly broad intraspecific variation, and set out to examine the signs of diversification and adaptation in this locally important vector species. To address both macro-scale diversity and micro-scale adaptations, we analyzed mitochondrial and nuclear DNA markers that have proven useful in similar study systems [ 5 – 9 , 11 , 12 , 15 – 17 , 19 , 72 – 74 , 80 – 84 ] and undertook a detailed qualitative/quantitative phenotypic assessment including head and forewing morphometrics [ 22 , 40 , 49 , 51 – 53 ]; we then used rich, specimen-specific ecological metadata (Additional file 1 : Table S1) to guide the interpretation of results.…”

Taxonomy, Evolution, and Biogeography of the Rhodniini Tribe (Hemiptera: Reduviidae)

“…Amplification of all loci was successful in R. robustus and in 6-9 of the species of the prolixus group, while in species of the groups pallescens and pictipes, amplification of more than three loci was not achieved [111]. Subsequent studies have used microsatellites to analyze intraspecific genetic structure in different populations of R. pallescens [111,112], R. nasutus [36], R. ecuadoriensis [113], and R. prolixus [22]. In populations of R. pallescens, field and laboratory specimens have been compared, and laboratory colonies of R. pallescens showed a different genetic structure than their wild relatives [112].…”

“…Studies of microsatellite markers in R. nasutus and R. ecuadoriensis showed that populations of these species from different geographic locations had genetic differences. For R. nasutus, four differentiated groups were revealed in eight geographic localities of the Brazilian Caatinga [36], and for R. ecuadoriensis, specimens in two biogeographically distinct localities of Ecuador had distinct genetic structures in association with other phenotypic differences [113]. Given its epidemiological importance, microsatellite markers were analyzed in wild and domestic populations of R. prolixus from Venezuela.…”