Ecological and genetic relationships of the Forest-M form among chromosomal and molecular forms of the malaria vector Anopheles gambiae sensu stricto

Y, Lee; Cornel, Anthony J.; Meneses, Claudio; Fofana, Abdrahamane; Andrianarivo, A. G.; McAbee, Rory D.; Fondjo, Étienne; Traorè, Sékou F.; Lanzaro, Gregory C.

doi:10.1186/1475-2875-8-75

Cited by 37 publications

(42 citation statements)

References 33 publications

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“…Although the resistance phenotypes of TEP1r B and TEP1r A have never been compared directly in the laboratory, the recent selective sweep of TEP1r B into West African populations of M suggests an advantage for this derived allele over both TEP1s and TEP1r A under field conditions experienced by the M form. The absence of TEP1r B from Cameroon populations of M is plausibly due to restricted gene flow between West and Central African populations of this form (28,29), as reinforced in this study by higher differentiation of reference genes in contrasts involving Cameroon (Fig. 2B), but also could entail spatially varying selection.…”

Section: Resultsmentioning

confidence: 65%

Adaptive divergence between incipient species of Anopheles gambiae increases resistance to Plasmodium

White

Lawniczak

Cheng

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

128

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The African malaria mosquito Anopheles gambiae is diversifying into ecotypes known as M and S forms. This process is thought to be promoted by adaptation to different larval habitats, but its genetic underpinnings remain elusive. To identify candidate targets of divergent natural selection in M and S, we performed genomewide scanning in paired population samples from Mali, followed by resequencing and genotyping from five locations in West, Central, and East Africa. Genome scans revealed a significant peak of M-S divergence on chromosome 3L, overlapping five known or suspected immune response genes. Resequencing implicated a selective target at or near the TEP1 gene, whose complement C3-like product has antiparasitic and antibacterial activity. Sequencing and allele-specific genotyping showed that an allelic variant of TEP1 has been swept to fixation in M samples from Mali and Burkina Faso and is spreading into neighboring Ghana, but is absent from M sampled in Cameroon, and from all sampled S populations. Sequence comparison demonstrates that this allele is related to, but distinct from, TEP1 alleles of known resistance phenotype. Experimental parasite infections of advanced mosquito intercrosses demonstrated a strong association between this TEP1 variant and resistance to both rodent malaria and the native human malaria parasite Plasmodium falciparum. Although malaria parasites may not be direct agents of pathogen-mediated selection at TEP1 in nature-where larvae may be the more vulnerable life stage-the process of adaptive divergence between M and S has potential consequences for malaria transmission.ecological speciation | malaria vector | population genomics | thioester immune gene

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Section: Resultsmentioning

confidence: 65%

Adaptive divergence between incipient species of Anopheles gambiae increases resistance to Plasmodium

White

Lawniczak

Cheng

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

128

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“…Molecular karyotyping of 2Rb (Lobo et al 2010) performed on individual mosquito DNA aliquots after Illumina libraries had been prepared from pooled DNA revealed a frequency of 2Rb ranging from 7% in the southern to 90% in the northern population pools, respectively (and 67% in the central locality). Thus, as expected (Coluzzi et al 1979;Lee et al 2009), 2Rb is clinally distributed along the arid-mesic latitudinal gradient in a pattern that parallels the 2La inversion. These data also indicate that although alternative 2Rb arrangements predominate at opposite ends of the cline, both arrangements are present in the two population pools, presumably resulting in some dampening of observed levels of divergence in the region spanned by 2Rb between northern and southern population samples.…”

Section: Genomic Patterns Of Divergence Between Endpoint Populationsmentioning

confidence: 80%

Ecological Genomics ofAnopheles gambiaeAlong a Latitudinal Cline: A Population-Resequencing Approach

et al. 2012

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The association between fitness-related phenotypic traits and an environmental gradient offers one of the best opportunities to study the interplay between natural selection and migration. In cases in which specific genetic variants also show such clinal patterns, it may be possible to uncover the mutations responsible for local adaptation. The malaria vector, Anopheles gambiae, is associated with a latitudinal cline in aridity in Cameroon; a large inversion on chromosome 2L of this mosquito shows large differences in frequency along this cline, with high frequencies of the inverted karyotype present in northern, more arid populations and an almost complete absence of the inverted arrangement in southern populations. Here we use a genome resequencing approach to investigate patterns of population divergence along the cline. By sequencing pools of individuals from both ends of the cline as well as in the center of the cline-where the inversion is present in intermediate frequency-we demonstrate almost complete panmixia across collinear parts of the genome and high levels of differentiation in inverted parts of the genome. Sequencing of separate pools of each inversion arrangement in the center of the cline reveals large amounts of gene flux (i.e., gene conversion and double crossovers) even within inverted regions, especially away from the inversion breakpoints. The interplay between natural selection, migration, and gene flux allows us to identify several candidate genes responsible for the match between inversion frequency and environmental variables. These results, coupled with similar conclusions from studies of clinal variation in Drosophila, point to a number of important biological functions associated with local environmental adaptation.

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“…Different populations are under distinct selective pressures, including exposure to other pathogens, and this could yield local differences between M and S forms for malaria susceptibility. Also, the evolutionary and demographic history of the M and S forms is not yet clear, and complex population admixtures are observed [12,17], as well as reproductively isolated founder populations with distinct ecological characteristics such as Goundry [19], Forest-M and Mopti-M forms [5]. Thus, different populations of the M or S form might not all share the same evolutionary history, and could therefore display different response to malaria parasites.…”

Section: Discussionmentioning

confidence: 99%

“…Genetic subdivision within A. gambiae allows fine ecological partitioning of the species, resulting in spatial and temporal expansion of malaria transmission [4,5]. Two population subgroups of A. gambiae , referred to as molecular forms, serve as an example.…”

Section: Introductionmentioning

confidence: 99%

Equivalent susceptibility of Anopheles gambiae M and S molecular forms and Anopheles arabiensis to Plasmodium falciparum infection in Burkina Faso

Gnémé

Guelbéogo

Riehle

et al. 2013

Malar J

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BackgroundThe Anopheles gambiae sensu lato (s.l.) species complex in Burkina Faso consists of Anopheles arabiensis, and molecular forms M and S of Anopheles gambiae sensu stricto (s.s.). Previous studies comparing the M and S forms for level of infection with Plasmodium falciparum have yielded conflicting results.MethodsMosquito larvae were sampled from natural pools, reared to adulthood under controlled conditions, and challenged with natural P. falciparum by experimental feeding with blood from gametocyte carriers. Oocyst infection prevalence and intensity was determined one week after infection. DNA from carcasses was genotyped to identify species and molecular form.ResultsIn total, 7,400 adult mosquitoes grown from wild-caught larvae were challenged with gametocytes in 29 experimental infections spanning four transmission seasons. The overall infection prevalence averaged 40.7% for A. gambiae M form, 41.4% for A. gambiae S form, and 40.1% for A. arabiensis. There was no significant difference in infection prevalence or intensity between the three population groups. Notably, infection experiments in which the population groups were challenged in parallel on the same infective blood displayed less infection difference between population groups, while infections with less balanced composition of population groups had lower statistical power and displayed apparent differences that fluctuated more often from the null average.ConclusionThe study clearly establishes that, at the study site in Burkina Faso, there is no difference in genetic susceptibility to P. falciparum infection between three sympatric population groups of the A. gambiae s.l. complex. Feeding the mosquito groups on the same infective blood meal greatly increases statistical power. Conversely, comparison of the different mosquito groups between, rather than within, infections yields larger apparent difference between mosquito groups, resulting from lower statistical power and greater noise, and could lead to false-positive results. In making infection comparisons between population groups, it is more accurate to compare the different groups after feeding simultaneously upon the same infective blood.

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Ecological and genetic relationships of the Forest-M form among chromosomal and molecular forms of the malaria vector Anopheles gambiae sensu stricto

Cited by 37 publications

References 33 publications

Adaptive divergence between incipient species of Anopheles gambiae increases resistance to Plasmodium

Adaptive divergence between incipient species of Anopheles gambiae increases resistance to Plasmodium

Ecological Genomics ofAnopheles gambiaeAlong a Latitudinal Cline: A Population-Resequencing Approach

Equivalent susceptibility of Anopheles gambiae M and S molecular forms and Anopheles arabiensis to Plasmodium falciparum infection in Burkina Faso

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