Genomic insights into adaptive divergence and speciation among malaria vectors of theAnopheles niligroup

Abstract

Ongoing speciation in the most important African malaria vectors gives rise to cryptic populations, which differ remarkably in their behavior, ecology, and capacity to vector malaria parasites. Understanding the population structure and the drivers of genetic differentiation among mosquitoes is crucial for effective disease control because heterogeneity within vector species contributes to variability in malaria cases and allow fractions of populations to escape control efforts. To examine population structure and the potential impacts of recent large-scale control interventions, we have investigated the genomic patterns of differentiation in mosquitoes belonging to the Anopheles nili group-a large taxonomic group that diverged ~3 Myr ago. Using 4,343 single nucleotide polymorphisms (SNPs), we detected strong population structure characterized by high-F ST values between multiple divergent populations adapted to different habitats within the Central African rainforest. Delineating the cryptic species within the Anopheles nili group is challenging due to incongruence between morphology, ribosomal DNA, and SNP markers consistent with incomplete lineage sorting and/or interspecific gene flow. A very high proportion of loci are fixed (F ST = 1) within the genome of putative species, which suggests that ecological and/or reproductive barriers are maintained by strong selection on a substantial number of genes.

The role of hybridization during ecological divergence of southwestern white pine (Pinus strobiformis) and limber pine (P. flexilis)

“…Such novel allelic combinations have often contributed to the ability of populations to colonize new niches that are intermediate but beyond the climatic conditions experienced by the parental species (De Carvalho et al., ; De La Torre, Wang, Jaquish, & Aitken, ; Geraldes et al., ; Hamilton et al., ). Presence of a locally adapted and historical hybrid zone is supported by the absence of β outliers in our genomic cline results (Fouet, Kamdem, Gamez, & White, ), as well as by a recent study identifying high Q ST values associated with physiological traits primarily linked to drought tolerance within Periphery (Goodrich, Waring, & Kolb, ). The geographic cline in h , asymmetry in excess ancestry loci towards P. flexilis and elevated estimates of F ST–periphery , however, indicate the potential for geographically driven neutral introgression to generate biased signals of local adaptation within the peripheral populations (Geraldes et al., ).…”

Dynamics of Plasmodium vivax populations in border areas of the Greater Mekong sub-region during malaria elimination

“…The genetic differentiation between the contemporary parasite populations is an indication of independent evolution of these isolated parasite populations as also documented for the P. falciparum parasites [37]. In addition, heterogeneity within vector populations could affect transmission [74] and population structure of the parasites [75]. The notable shift in vector populations observed in western Thailand may also be responsible for shaping the parasite population structure [76].…”

Assessing connectivity despite high diversity in island populations of a malaria mosquito

“…We found two sweeps on insecticide-related genes that are common targets of selection elsewhere but which have incompletely colonized the Ssese Islands: one on cytochrome P450 monooxygenase Cyp9K1 [44, 45] present on some islands, and another on glutathione Stransferase genes ( Gste1-Gste7 ; [46–49]) at extremely low frequency on the islands. That the selective sweeps targeting these loci [4] have not fully colonized the islands despite the advantage in detoxifying pyrethroids and DDT suggests a lack of contemporary exchange.…”