Would tropical climatic variations impact the genetic variability of triatomines: Rhodnius ecuadoriensis, principal vector of Chagas disease in Ecuador?

Villacís, Anita G.; Bustillos, Juan José; Depickère, Stéphanie; Sánchez, Dino; Yumiseva, César A.; Troya-Zuleta, Ana; Barnabé, Christian; Grijalva, Mario J.; Brenière, Simone Frédérique

doi:10.1016/j.actatropica.2020.105530

Cited by 9 publications

(7 citation statements)

References 43 publications

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“…Eradication of ‘domesticated’ triatomines has been the mainstay of disease control in the past (e.g., Triatoma infestans 10 , Rhodnius prolixus and Triatoma dimidiata 11 ). However, wild (e.g., T. infestans 12 and R. prolixus 13 ) and/or secondary competent species of triatomines (e.g., Triatoma sordida 14 , Triatoma maculata and Rhodnius pallescens 15 , Panstrongylus howardi 16 and P. chinai 17 ) can occupy empty domestic niches and continue to jeopardise Chagas disease control strategies.…”

Section: Mainmentioning

confidence: 99%

The genomic basis of domestic colonisation and dispersal in Chagas disease vectors

Hernandez-Castro

Villacis

Jacobs

et al. 2021

Preprint

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The biology of vector adaptation to the human habitat remains poorly understood for many arthropod-borne diseases but underpins effective and sustainable disease control. We adopted a landscape genomics approach to investigate gene flow, signatures of local adaptation, and drivers of population structure among multiple linked wild and domestic population pairs in Rhodnius ecuadoriensis, an important vector of Chagas Disease. Evidence of high triatomine gene flow (FST) between wild and domestic ecotopes at sites throughout the study area indicate insecticide-based control will be hindered by constant re-infestation of houses. Genome scans revealed genetic loci with strong signal of local adaptation to the domestic setting, which we mapped to annotated regions in the Rhodnius prolixus genome. Our landscape genomic mixed effects models showed Rhodnius ecuadoriensis population structure and connectivity is driven by landscape elevation at a regional scale. Our ecologically- and spatially-explicit vector dispersal model enables targeted vector control and recommends spatially discrete, periodic interventions to local authorities as more efficacious than current, haphazard approaches. In tandem, evidence for parallel genomic adaptation to colonisation of the domestic environment at multiple sites sheds new light on the evolutionary basis of adaptation to the human host in arthropod vectors.

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Section: Mainmentioning

confidence: 99%

The genomic basis of domestic colonisation and dispersal in Chagas disease vectors

Hernandez-Castro

Villacis

Jacobs

et al. 2021

Preprint

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“…We note that the R. ecuadoriensis cytb sequences studied by Villacis et al [67,68] are not available in NCBI's GenBank or in EMBL-EBI's European Nucleotide Archive (ENA).…”

Section: Molecular Analysesmentioning

confidence: 99%

“…We reasoned that the broad ecological flexibility of R. ecuadoriensis was likely to correlate with similarly broad intraspecific variation, and set 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][6][7][8][9]11,12,[15][16][17]19,[67][68][69][70][76][77][78][79][80] and undertook a detailed qualitative/quantitative phenotypic assessment including head and forewing morphometrics [22,45,[47][48][49]81]; we then used rich, specimen-specific ecological metadata to guide the interpretation of results. We nevertheless note that our results are based on a relatively limited (albeit overall well representative) sample of geographic-ecological populations and on just two genetic loci (albeit two that are known to be informative for problems similar to the one we tackled).…”

Section: Molecular Analyses 3 -Species Trees and Bayesian Hypothesis mentioning

confidence: 99%

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

Abad‐Franch

Monteiro

Pavan

et al. 2020

Preprint

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BackgroundTriatomine bugs, the vectors of Chagas disease, associate with vertebrate hosts in highly diverse ecotopes. When these blood-sucking bugs adapt to new microhabitats, their phenotypes may change. Although understanding phenotypic variation is key to the study of adaptive evolution and central to phenotype-based taxonomy, the drivers of phenotypic change and diversity in triatomines remain poorly understood.Methods/FindingsWe combined a detailed phenotypic appraisal (including morphology and morphometrics) with mitochondrial cytb and nuclear ITS2 DNA-sequence analyses to study Rhodnius ecuadoriensis populations from across the species’ range. We found three major, naked-eye phenotypic variants. Southern-Andean bugs (SW Ecuador/NW Peru) from house and vertebrate-nest microhabitats are typical, light-colored, small bugs with short heads/wings. Northern-Andean bugs (W Ecuador wet-forest palms) are dark, large bugs with long heads/wings. Finally, northern-lowland bugs (coastal Ecuador dry-forest palms) are light-colored and medium-sized. Wing and (size-free) head shapes are similar across Ecuadorian populations, regardless of habitat or naked-eye phenotype, but distinct in Peruvian bugs. Bayesian phylogenetic and multispecies-coalescent DNA-sequence analyses strongly suggest that Ecuadorian and Peruvian populations are two independently-evolving lineages, with little within-lineage structuring/differentiation.ConclusionsWe report sharp naked-eye phenotypic divergence of genetically similar Ecuadorian R. ecuadoriensis (house/nest southern-Andean vs. palm-dwelling northern bugs; and palm-dwelling Andean vs. lowland); and sharp naked-eye phenotypic similarity of typical, yet genetically distinct, southern-Andean bugs from house and nest (but not palm) microhabitats (SW Ecuador vs. NW Peru). This remarkable phenotypic diversity within a single nominal species likely stems from microhabitat adaptations possibly involving predator-driven selective pressure (yielding substrate-matching camouflage coloration) and a shift from palm-crown to vertebrate-nest microhabitats (yielding smaller bodies and shorter heads and wings). These findings shed new light on the origins of phenotypic diversity in triatomines, warn against excess reliance on phenotype-based triatomine-bug taxonomy, and confirm the Triatominae as an informative model-system for the study of phenotypic change under ecological pressure.Author summaryTriatomine bugs feed on the blood of vertebrates including humans and transmit the parasite that causes Chagas disease. The bugs, of which 150+ species are known, are highly diverse in size, shape, and color. Some species look so similar that they are commonly confused, whereas a few same-species populations look so different that they were thought to be separate species. Despite the crucial role of naked-eye phenotypes in triatomine-bug identification and classification (which are essential for vector control-surveillance), the origins of this variation remain unclear. Here, we describe a striking case of phenotypic divergence, with genetically similar bugs looking very different from one another, and phenotypic convergence, with bugs from two genetically distinct populations (likely on their way to speciation) looking very similar – and all within a single nominal species, Rhodnius ecuadoriensis. Phenotypically divergent populations occupy different ecological regions (wet vs. dry) and microhabitats (palm-crowns vs. vertebrate nests), whereas convergent populations occupy man-made and nest (but not palm) microhabitats. These findings suggest that triatomines can ‘respond’ to ecological novelty by changing their external, naked-eye phenotypes as they adapt to new microhabitats. We therefore warn that phenotypic traits such as overall size or color may confound triatomine-bug species identification and classification.

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“…Ecuador es un país altamente vulnerable a factores externos de diversa índole debida a su ubicación geográfica, que van desde eventos de origen natural o a actuaciones androgénicas (Oñate-Valdivieso et al, 2021;Villacís et al, 2020). Las consecuencias del cambio climático o la intensificación de fenómenos de variabilidad natural, como El Niño-Oscilación del Sur (ENOS), inciden de forma adversa en el desarrollo del país ( Serrano-Castro et al, 2019).…”

Section: Introductionunclassified

Evaluación de la variabilidad climática en el cantón Chillanes mediante los parámetros de la precipitación y la temperatura

Verdezoto-Mendoza

Allaica

Serrano-Castro

et al. 2021

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Introducción: La variabilidad climática en las últimas décadas se ha intensificado en la región de Sudamérica, lo que hace imperativo explorar estrategias adecuadas de adaptación y mitigación para compensar sus impactos adversos actuales y futuros. Objetivo: Evaluar la variabilidad climática en el cantón Chillanes situado en la Hoya del Chimbo, provincia de Bolívar, Ecuador, mediante los parámetros de la precipitación y la temperatura. Metodología: Se utilizó datos extraídos de series mensuales meteorológicos de precipitación y temperatura de la Estación Climática Chillanes-M130 del Instituto Nacional de Meteorología e Hidrología (INAMH), periodo 1989 – 2015. La serie exteriorizó datos faltantes que fueron completados utilizando un método univariado del criterio de las diferencias y posteriormente se verificó la anomalía climática mediante el cálculo de las anomalías climáticas de la precipitación y la temperatura. Resultados: El análisis ejecutado en los 27 años no exteriorizó anomalías de la precipitación examinado a un 95% de confianza respecto a la media, por lo tanto, se considera un comportamiento estable a pesar de la existencia de fenómenos naturales de intensidad fuerte de precipitaciones como el fenómeno El Niño en el año de 1997. Conclusiones: La temperatura presentó una anomalía positiva que revela que la temperatura promedio anual está por encima del promedio histórico registrado en los 27 años de estudio, exteriorizando un incremento de la temperatura de 0,8 °C, lo que indica que respecto a la temperatura existe en el lugar de estudio una variabilidad climática.

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Would tropical climatic variations impact the genetic variability of triatomines: Rhodnius ecuadoriensis, principal vector of Chagas disease in Ecuador?

Cited by 9 publications

References 43 publications

The genomic basis of domestic colonisation and dispersal in Chagas disease vectors

The genomic basis of domestic colonisation and dispersal in Chagas disease vectors

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

Evaluación de la variabilidad climática en el cantón Chillanes mediante los parámetros de la precipitación y la temperatura

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