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1. Radiation with reticulation marks the origin of a major malaria vector

   https://doi.org/10.1073/pnas.2018142117  

   Small, Scott T.; Labbé, Frédéric; Lobo, Neil F.; Koekemoer, Lizette L.; Sikaala, Chadwick H.; Neafsey, Daniel E.; Hahn, Matthew W.; Fontaine, Michael C.; Besansky, Nora J. (December 2020, Proceedings of the National Academy of Sciences)

   null (Ed.)

   Advances in genomics have led to an appreciation that introgression is common, but its evolutionary consequences are poorly understood. In recent species radiations the sharing of genetic variation across porous species boundaries can facilitate adaptation to new environments and generate novel phenotypes, which may contribute to further diversification. Most Anopheles mosquito species that are of major importance as human malaria vectors have evolved within recent and rapid radiations of largely nonvector species. Here, we focus on one of the most medically important yet understudied anopheline radiations, the Afrotropical Anopheles funestus complex (AFC), to investigate the role of introgression in its diversification and the possible link between introgression and vector potential. The AFC comprises at least seven morphologically similar species, yet only An. funestus sensu stricto is a highly efficient malaria vector with a pan-African distribution. Based on de novo genome assemblies and additional whole-genome resequencing, we use phylogenomic and population genomic analyses to establish species relationships. We show that extensive interspecific gene flow involving multiple species pairs has shaped the evolutionary history of the AFC since its diversification. The most recent introgression event involved a massive and asymmetrical movement of genes from a distantly related AFC lineage into An. funestus , an event that predated and plausibly facilitated its subsequent dramatic geographic range expansion across most of tropical Africa. We propose that introgression may be a common mechanism facilitating adaptation to new environments and enhancing vectorial capacity in Anopheles mosquitoes. 

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2. Genetic evidence for the origin of Aedes aegypti , the yellow fever mosquito, in the southwestern Indian Ocean

   https://doi.org/10.1111/mec.15590  

   Soghigian, John; Gloria‐Soria, Andrea; Robert, Vincent; Le_Goff, Gilbert; Failloux, Anna‐Bella; Powell, Jeffrey_R (August 2020, Molecular Ecology)

   Abstract Aedes aegyptiis among the best‐studied mosquitoes due to its critical role as a vector of human pathogens and ease of laboratory rearing. Until now, this species was thought to have originated in continental Africa, and subsequently colonized much of the world following the establishment of global trade routes. However, populations of this mosquito on the islands in the southwestern Indian Ocean (SWIO), where the species occurs with its nearest relatives referred to as the Aegypti Group, have received little study. We re‐evaluated the evolutionary history ofAe. aegyptiand these relatives, using three data sets: nucleotide sequence data, 18,489 SNPs and 12 microsatellites. We found that: (a) the Aegypti Group diverged 16 MYA (95% HPD: 7–28 MYA) from its nearest African/Asian ancestor; (b) SWIO populations ofAe. aegyptiare basal to continental African populations; (c) after diverging 7 MYA (95% HPD: 4–15 MYA) from its nearest formally described relative (Ae. mascarensis),Ae. aegyptimoved to continental Africa less than 85,000 years ago, where it recently (<1,000 years ago) split into two recognized subspeciesAe. aegypti formosusand a human commensal,Ae. aegypti aegypti; (d) the Madagascar samples form a clade more distant from all otherAe. aegyptithan the named speciesAe. mascarensis, implying that Madagascar may harbour a new cryptic species; and (e) there is evidence of introgression betweenAe. mascarensisandAe. aegyption Réunion, and between the two subspecies elsewhere in the SWIO, a likely consequence of recent introductions of domesticAe. aegypti aegyptifrom Asia. 

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3. RNA sequencing analysis of viromes of Aedes albopictus and Aedes vexans collected from NEON sites

   https://doi.org/10.1073/pnas.2403591122  

   Paull, Sara_H; Spurbeck, Rachel_R; Hasan, Nur_A; Brumfield, Kyle_D; Catlin, Lindsay_A; Netherland, Jr., Michael_J; Smith, Anthony_K; Thibault, Katherine_M; Colwell, Rita_R (May 2025, Proceedings of the National Academy of Sciences)

   Climate change is significantly impacting the geographic range of many animal species and their associated microorganisms, hence influencing emergence of vector-borne diseases. Mosquito-borne viruses represent a potential major reservoir of human pathogens, highlighting the need for improved understanding of ecological factors associated with variation in the mosquito viral community (virome). Here, a subtractive hybridization method coupled with RNAseq of individual mosquito specimens was used to profile RNA viromes of individual co-occurringAedes albopictusandAedes vexansmosquitoes across a 2,000 km spatial scale. Samples were collected and archived by the National Ecological Observatory Network (NEON) from four ecologically variable sites in the Southeastern United States between 2018 and 2019. Results of multivariate analysis suggest that mosquito species are an important factor in RNA viral community composition. Significantly higher viral diversity was detected inA. albopictuscompared toA.vexans. However, season, year, and site of sample collection did not show strong association with virome profiles, supporting the hypothesis that factors unique to the mosquito host species (e.g., larval habitat or vector competence) influence the structure of mosquito viromes. 

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4. Aedes aegypti gut transcriptomes respond differently to microbiome transplants from field‐caught or laboratory‐reared mosquitoes

   https://doi.org/10.1111/1462-2920.16576  

   Hegde, Shivanand; Brettell, Laura_E; Quek, Shannon; Etebari, Kayvan; Saldaña, Miguel_A; Asgari, Sassan; Coon, Kerri_L; Heinz, Eva; Hughes, Grant_L (January 2024, Environmental Microbiology)

   Abstract The mosquito microbiome is critical for host development and plays a major role in many aspects of mosquito biology. While the microbiome is commonly dominated by a small number of genera, there is considerable variation in composition among mosquito species, life stages, and geography. How the host controls and is affected by this variation is unclear. Using microbiome transplant experiments, we asked whether there were differences in transcriptional responses when mosquitoes of different species were used as microbiome donors. We used microbiomes from four different donor species spanning the phylogenetic breadth of the Culicidae, collected either from the laboratory or the field. We found that when recipients received a microbiome from a donor reared in the laboratory, the response was remarkably similar regardless of donor species. However, when the donor had been collected from the field, many more genes were differentially expressed. We also found that while the transplant procedure did have some effect on the host transcriptome, this is likely to have had a limited effect on mosquito fitness. Overall, our results highlight the possibility that variation in mosquito microbiome communities is associated with variability in host–microbiome interactions and further demonstrate the utility of the microbiome transplantation technique for investigating host–microbe interactions in mosquitoes. 

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5. MosAIC: An annotated collection of mosquito-associated bacteria with high-quality genome assemblies

   https://doi.org/10.1371/journal.pbio.3002897  

   Foo, Aidan; Brettell, Laura E; Nichols, Holly L; Medina_Muñoz, Miguel; Lysne, Jessica A; Dhokiya, Vishaal; Hoque, Ananya F; Brackney, Doug E; Caragata, Eric P; Hutchinson, Michael L; et al (November 2024, PLOS Biology)

   Gendrin, Mathilde (Ed.)

   Mosquitoes transmit medically important human pathogens, including viruses like dengue virus and parasites such asPlasmodiumspp., the causative agent of malaria. Mosquito microbiomes are critically important for the ability of mosquitoes to transmit disease-causing agents. However, while large collections of bacterial isolates and genomic data exist for vertebrate microbiomes, the vast majority of work in mosquitoes to date is based on 16S rRNA gene amplicon data that provides limited taxonomic resolution and no functional information. To address this gap and facilitate future studies using experimental microbiome manipulations, we generated a bacterialMosquito-AssociatedIsolateCollection (MosAIC) consisting of 392 bacterial isolates with extensive metadata and high-quality draft genome assemblies that are publicly available, both isolates and sequence data, for use by the scientific community. MosAIC encompasses 142 species spanning 29 bacterial families, with members of theEnterobacteriaceaecomprising 40% of the collection. Phylogenomic analysis of 3 genera,Enterobacter,Serratia, andElizabethkingia, reveal lineages of mosquito-associated bacteria isolated from different mosquito species in multiple laboratories. Investigation into species’ pangenomes further reveals clusters of genes specific to these lineages, which are of interest for future work to test for functions connected to mosquito host association. Altogether, we describe the generation of a physical collection of mosquito-associated bacterial isolates, their genomic data, and analyses of selected groups in context of genome data from closely related isolates, providing a unique, highly valuable resource for research on bacterial colonisation and adaptation within mosquito hosts. Future efforts will expand the collection to include broader geographic and host species representation, especially from individuals collected from field populations, as well as other mosquito-associated microbes, including fungi, archaea, and protozoa. 

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