Transcriptome-based phylogenomic analysis reveals evidence of ancient hybridization events in the Mepraia genus (Hemiptera: Reduviidae: Triatominae)

IntroductionThe Mepraia genus is composed of three endemic species in Chile, namely Mepraia spinolai, Mepraia gajardoi, and Mepraia parapatrica, all capable of transmitting the causative agent of Chagas disease. Although species divergence within this genus is supported by morphological, molecular, and geological evidence, it has never been validated by genome-wide data.MethodsIn this sense, a pioneering phylogenomic study was conducted using transcriptome data of the three species, aiming to infer robust phylogenies and evaluate the impact of interspecific gene flow on the evolution of these insects. Our transcriptomes were used to robustly infer the phylogenetic relationships, employing multi-species coalescent and supermatrix approaches, as well as to investigate the occurrence of introgression.Results and discussionThe inferred phylogenies support the monophyly of the three described taxa and infer divergence times, although gene trees display high levels of discordance. Our results indicate widespread introgression among Mepraia lineages. Thus, our results support that Mepraia diversification occurred in a short period resulting in reticulate phylogenies and low genetic diversity. Additionally, we obtained evidence of introgression suggesting that ancient hybridization has had a major role in the evolution of the three Mepraia species

Characterization of Female External Genitalia and Eggs of Four South American Species of the Triatoma Laporte, 1832 Genus (Hemiptera: Reduviidae: Triatominae)

Triatoma is the most diversified and one of the most important genera from an epidemiological perspective. Given the difficulty in identifying some species of the Triatoma genus, morphological, histological, and morphometric studies were performed to provide new characters that make it possible to differentiate T. garciabesi, T. guasayana, T. patagonica, and T. sordida sensu stricto, triatomines that overlap geographically and have vector potential. Through the external female genitalia, as well as morphology, morphometry, and histology of eggshells, it was possible to discriminate the four species. In addition, this study reinforces the taxonomic validity of T. garciabesi and provides new data for discussion on systematic issues of T. guasayana and T. patagonica

Differential transcriptome analysis supports <i>Rhodnius montenegrensis</i> and <i>Rhodnius robustus</i> (Hemiptera, Reduviidae, Triatominae) as distinct species

<div><p>Chagas disease is one of the main parasitic diseases found in Latin America and it is estimated that between six and seven million people are infected worldwide. Its etiologic agent, the protozoan <i>Trypanosoma cruzi</i>, is transmitted by triatomines, some of which from the genus <i>Rhodnius</i>. Twenty species are currently recognized in this genus, including some closely related species with low levels of morphological differentiation, such as <i>Rhodnius montenegrensis</i> and <i>Rhodnius robustus</i>. In order to investigate genetic differences between these two species, we generated large-scale RNA-sequencing data (consisting of four RNA-seq libraries) from the heads and salivary glands of males of <i>R</i>. <i>montenegrensis</i> and <i>R</i>. <i>robustus</i>. Transcriptome assemblies produced for each species resulted in 64,952 contigs for <i>R</i>. <i>montenegrensis</i> and 70,894 contigs for <i>R</i>. <i>robustus</i>, with N50 of approximately 2,100 for both species. SNP calling based on the more complete <i>R</i>. <i>robustus</i> assembly revealed 3,055 fixed interspecific differences and 216 transcripts with high levels of divergence which contained only fixed differences between the two species. A gene ontology enrichment analysis revealed that these highly differentiated transcripts were enriched for eight GO terms related to AP-2 adaptor complex, as well as other interesting genes that could be involved in their differentiation. The results show that <i>R</i>. <i>montenegrensis</i> and <i>R</i>. <i>robustus</i> have a substantial quantity of fixed interspecific polymorphisms, which suggests a high degree of genetic divergence between the two species and likely corroborates the species status of <i>R</i>. <i>montenegrensis</i>.</p></div

Gene Ontology level 2 terms with frequencies greater than 1% found for coding regions of unigenes derived from the head transcriptomes of males of <i>R</i>. <i>montenegrensis</i> and <i>R</i>. <i>robustus</i>.

<p>Gene Ontology level 2 terms with frequencies greater than 1% found for coding regions of unigenes derived from the head transcriptomes of males of <i>R</i>. <i>montenegrensis</i> and <i>R</i>. <i>robustus</i>.</p

Absolute allele frequency difference averages of shared SNPs of <i>R</i>. <i>montenegrensis</i> and <i>R</i>. <i>robustus</i> per transcript ().

<p>We highlight in red the class of SNPs with = 1.</p

Distribution of absolute allele frequency differences (D) of the 13,696 shared SNPs between <i>R</i>. <i>montenegrensis</i> and <i>R</i>. <i>robustus</i>.

<p>We highlight in red the class of SNPs with D = 1.</p

Summary of sequencing and assembly statistics based on cephalic tissue from males of <i>R</i>. <i>montenegrensis</i> (Rm) and <i>R</i>. <i>robustus</i> (Rr).

<p>Summary of sequencing and assembly statistics based on cephalic tissue from males of <i>R</i>. <i>montenegrensis</i> (Rm) and <i>R</i>. <i>robustus</i> (Rr).</p