scholarly journals Patterns of Mitochondrial Variation Within and Between African Malaria Vectors, Anopheles gambiae and An. arabiensis, Suggest Extensive Gene Flow

Genetics ◽  
1997 ◽  
Vol 147 (4) ◽  
pp. 1817-1828 ◽  
Author(s):  
Nora J Besansky ◽  
Tovi Lehmann ◽  
G Thomas Fahey ◽  
Didier Fontenille ◽  
Lawrence E O Braack ◽  
...  
Keyword(s):  
Gene Flow ◽  
Anopheles Gambiae ◽  
Genetic Divergence ◽  
Isolation By Distance ◽  
Haplotype Diversity ◽  
Introgressive Hybridization ◽  
Sub Saharan Africa ◽  
Malaria Vectors ◽  
Amino Acid Difference ◽  
Mtdna Sequence

Abstract Anopheles gambiae and An. arabiensis are mosquito species responsible for most malaria transmission in sub-Saharan Africa. They are also closely related sibling species that share chromosomal and molecular polymorphisms as a consequence of incomplete lineage sorting or introgressive hybridization. To help resolve these processes, this study examined the partitioning of mtDNA sequence variation within and between species across Africa, from both population genetic and phylogeographic perspectives. Based on partial gene sequences from the cytochrome b, ND1 and ND5 genes, haplotype diversity was high but sequences were very closely related. Within species, little or no population subdivision was detected, and there was no evidence for isolation by distance. Between species, there were no fixed nucleotide differences, a high proportion of shared polymorphisms, and eight haplotypes in common over distances as great as 6000 km. Only one of 16 shared polymorphisms led to an amino acid difference, and there was no compelling evidence for nonneutral variation. Parsimony networks constructed of haplotypes from both species revealed no correspondence of haplotype with either geography or taxonomy. This trend of low intraspecific genetic divergence is consistent with evidence from allozyme and microsatellite data and is interpreted in terms of both extensive gene flow and recent range expansion from relatively large, stable populations. We argue that retention of ancestral polymorphisms is a plausible but insufficient explanation for low interspecific genetic divergence, and that extensive hybridization is a contributing factor.

scholarly journals Ecological drivers of genetic connectivity for African malaria vectors Anopheles gambiae and An. arabiensis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Elizabeth Hemming-Schroeder ◽  
Daibin Zhong ◽  
Maxwell Machani ◽  
Hoan Nguyen ◽  
Sarah Thong ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Anopheles Gambiae ◽  
Population Genetic ◽  
Sub Saharan Africa ◽  
Tree Cover ◽  
Genetic Connectivity ◽  
Malaria Vectors ◽  
Western Kenya ◽  
Sub Saharan

AbstractAnopheles gambiae and An. arabiensis are major malaria vectors in sub-Saharan Africa. Knowledge of how geographical factors drive the dispersal and gene flow of malaria vectors can help in combatting insecticide resistance spread and planning new vector control interventions. Here, we used a landscape genetics approach to investigate population relatedness and genetic connectivity of An. gambiae and An. arabiensis across Kenya and determined the changes in mosquito population genetic diversity after 20 years of intensive malaria control efforts. We found a significant reduction in genetic diversity in An. gambiae, but not in An. arabiensis as compared to prior to the 20-year period in western Kenya. Significant population structure among populations was found for both species. The most important ecological driver for dispersal and gene flow of An. gambiae and An. arabiensis was tree cover and cropland, respectively. These findings highlight that human induced environmental modifications may enhance genetic connectivity of malaria vectors.

scholarly journals Genetic diversity and extent of gene flow in the endangered Japanese population of Hodgson's hawk-eagle, Spizaetus nipalensis

2006 ◽  
Vol 16 (2) ◽  
pp. 113-129 ◽  
Author(s):  
SHIGEKI ASAI ◽  
YOSHIHIRO YAMAMOTO ◽  
SATOSHI YAMAGISHI
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Japanese Population ◽  
Isolation By Distance ◽  
Cladistic Analysis ◽  
Variable Region ◽  
Complete Sequence ◽  
Restricted Gene Flow ◽  
Critical Situation ◽  
Mtdna Sequence

The Japanese subspecies of Hodgson's Hawk-eagle, Spizaetus nipalensis orientalis, is considered threatened and has been designated as Endangered by the Japanese government. We determined the complete mitochondrial DNA (mtDNA) sequence of this species and designed a primer set to amplify a highly variable region of mtDNA, part of the control region (CR), based on this complete sequence. Using the primers, we amplified the CR and then determined the haplotypes of 178 samples collected at different sites in Japan. A nested cladistic analysis indicated that gene flow within some clades was restricted. The inference key implied that isolation by distance had caused the restriction of gene flow. Moreover, the ranges of the clades in which restricted gene flow was detected overlapped with the ranges of other clades. These results suggest that there is no fragmental population of Hodgson's Hawk-eagle in Japan and that this species has dispersed within short distances, at least in some lineages. Genetic diversity was high in comparison with other species. Therefore, at least in terms of genetic diversity, the Japanese population of Hodgson's Hawk-eagle is probably not in a critical situation.

scholarly journals Reduced human-biting preferences of the African malaria vectors Anopheles arabiensis and Anopheles gambiae in an urban context: controlled, competitive host-preference experiments in Tanzania

2020 ◽  
Author(s):  
Yeromin P Mlacha ◽  
Prosper P. Chaki ◽  
Athuman Muhili ◽  
Dennis J. Massue ◽  
Marcel Tanner ◽  
...  
Keyword(s):  
Vector Control ◽  
Anopheles Gambiae ◽  
Anopheles Arabiensis ◽  
Host Preference ◽  
Urban Setting ◽  
Sub Saharan Africa ◽  
Rural Setting ◽  
Malaria Vectors ◽  
Baited Traps ◽  
The Impact

Abstract BackgroundHost preference is a critical determinant of human exposure to vector-borne infections and the impact of vector control interventions. Widespread use of long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) across sub-Saharan Africa, which protect humans against mosquitoes, may select for altered host preference traits of malaria vectors over the long term. Here, the host preferences of Anopheles arabiensis and Anopheles gambiae sensu stricto (s.s.) were experimentally assessed in the field, using direct host-preference assays in two distinct ecological settings in Tanzania.MethodsEight Ifakara Tent Trap (ITT), four baited with humans and four with bovine calves, were simultaneously used to catch malaria vectors in open field sites in urban and rural Tanzania. The numbers of mosquitoes collected in human-baited traps versus calf-baited traps were used to estimate human feeding preference for each site's vector species. ResultsThe estimated proportion [95% confidence interval (CI)] of mosquitoes attacking humans rather than cattle was 0.60 [0.40, 0.77] for An. arabiensis in the rural setting and 0.61 [0.32, 0.85] for An. gambiae s.s. in the urban setting, indicating no preference for either host in both cases (P=0.32 and 0.46, respectively) and no difference in preference between the two (Odds Ratio (OR) [95%] = 0.95 [0.30, 3.01], P=0.924). However, only a quarter of An. arabiensis in the urban setting attacked humans (0.25 [0.09, 0.53]), indicating a preference for cattle that approached significance (P=0.08). Indeed, urban An. arabiensis were less likely to attack humans rather than cattle when compared to the same species in the rural setting (OR [95%] = 0.21 [0.05, 0.91], P =0.037). ConclusionUrban An. arabiensis had a stronger preference for cattle than the rural population and urban An. gambiae s.s. showed no clear preference for either humans or cattle. In the urban setting, both species exhibited stronger tendencies to attack cattle than previous studies of the same species in rural contexts. Cattle keeping may, therefore, particularly limit the impact of human-targeted vector control interventions in Dar es Salaam and perhaps in other African towns and cities.

scholarly journals Post-Disturbance Genetic Changes: The Impact of the 2010 Mega-Earthquake and Tsunami on Chilean Sandy Beach Fauna

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Antonio Brante ◽  
Garen Guzmán-Rendón ◽  
Erwin M. Barría ◽  
Marie-Laure Guillemin ◽  
Iván Vera-Escalona ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Haplotype Diversity ◽  
Population Expansion ◽  
Adult Survival ◽  
Genetic Changes ◽  
Species Response ◽  
Emerita Analoga ◽  
Mtdna Sequence ◽  
The Impact

Abstract Earthquake/tsunamis can have profound impacts on species and their genetic patterns. It is expected that the magnitude of this impact might depend on the species and the time since the disturbance occurs, nevertheless these assumptions remain mostly unexplored. Here we studied the genetic responses of the crustacean species Emerita analoga, Excirolana hirsuticauda, and Orchestoidea tuberculata to the 27F mega-earthquake/tsunami that occurred in Chile in February 2010. mtDNA sequence analyses revealed a lower haplotype diversity for E. analoga and E. hirsuticauda in impacted areas one month after the 27F, and the opposite for O. tuberculata. Three years after the 27F we observed a recovery in the genetic diversity of E. analoga and E. hirsuticauda and decrease in the genetic diversity in O. tuberculata in 2/3 of sampled areas. Emerita analoga displayed decrease of genetic differentiation and increase in gene flow explained by long-range population expansion. The other two species revealed slight increase in the number of genetic groups, little change in gene flow and no signal of population expansion associated to adult survival, rapid colonization, and capacity to burrow in the sand. Our results reveal that species response to a same disturbance event could be extremely diverse and depending on life-history traits and the magnitude of the effect.

scholarly journals Selective Introgression of Paracentric Inversions Between Two Sibling Species of the Anopheles gambiae Complex

Genetics ◽  
1997 ◽  
Vol 146 (1) ◽  
pp. 239-244
Author(s):  
A della Torre ◽  
L Merzagora ◽  
J R Powell ◽  
M Coluzzi
Keyword(s):  
Anopheles Gambiae ◽  
Behavioral Flexibility ◽  
Introgressive Hybridization ◽  
Sub Saharan Africa ◽  
X Chromosomes ◽  
Gambiae Complex ◽  
Chromosomal Inversions ◽  
Anopheles Gambiae Complex ◽  
Two Generations ◽  
Sub Saharan

The Anopheles gambiae complex includes the major vectors of malaria in sub-Saharan Africa where >80% of all world-wide cases occur. These mosquitoes are characterized by chromosomal inversions associated to the speciation process and to intraspecific ecological and behavioral flexibility. It has been postulated that introgressive hybridization has selectively transferred inversions on the second chromosome between A. gambiae and A. arabiensis, the two most important vectors of malaria. Here we directly test this hypothesis with laboratory experiments in which hybrid populations were established and the fate of chromosomal inversions were followed. Consistent with the hypothesis, “foreign” X chromosomes were eliminated within two generations, while some “foreign” second chromosomes persisted for the duration of the experiments and, judging from the excess of heterozygotes, established stable heterotic polymorphisms. Only those second chromosome inversions found naturally in the species could be introgressed.

scholarly journals Reduced human-biting preferences by the African malaria vectors Anopheles arabiensis and Anopheles gambiae in an urban context: Controlled, competitive host-preference experiments in Tanzania

2020 ◽  
Author(s):  
Yeromin P Mlacha ◽  
Prosper P. Chaki ◽  
Athuman Muhili ◽  
Dennis J. Massue ◽  
Marcel Tanner ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
Anopheles Arabiensis ◽  
Host Preference ◽  
Indoor Residual Spraying ◽  
Urban Setting ◽  
Sub Saharan Africa ◽  
Rural Setting ◽  
Malaria Vectors ◽  
Baited Traps ◽  
The Impact

Abstract BackgroundHost preference is a critical determinant of human exposure to vector-borne infections and also the impact of interventions. Widespread use of long-lasting insecticides treated nets (LLINs) and, indoor residual spraying (IRS) across sub-Saharan Africa, which protect humans against mosquitoes, may select for altered host preference traits of malaria vectors over the long term. Here, the host preferences of Anopheles arabiensis and Anopheles gambiae sensu stricto was experimentally assessed in the field, using direct host-preference assays in two distinct ecological settings in Tanzania. MethodsEight Ifakara Tent Trap (ITT), half of them baited with humans or bovine calves were simultaneously used to catch malaria vectors in open field sites urban and rural Tanzania. The numbers of mosquitoes collected in human-baited traps versus calf-baited traps were used to estimate human feeding preference of each malaria vector species present at each site. ResultsThe estimated proportion [95% confidence interval (CI)] of mosquitoes attacking humans rather than cattle was 0.60 [0.40, 0.77] for An. arabiensis in the rural setting and 0.61 [0.32, 0.85] for An. gambiae in the urban setting, indicating no preference for either host in both cases (P=0.32 and 0.46, respectively) and no difference in preference between the two (Odds Ratio (OR) [95%] = 0.95 [0.30, 3.01], P=0.924). However, only a quarter of An. arabiensis in the urban setting attacked humans (0.25 [0.09, 0.53]), indicating a preference for cattle that approached significance (P=0.08). Indeed, urban An. arabiensis were less likely to attack humans rather than cattle when compared to the same species in the rural setting (OR [95%] = 0.21 [0.05, 0.91], P =0.037). ConclusionUrban An. arabiensis had a stronger preference for cattle than the rural population in this or previous studies, all of which reported similar traits for this species in rural contexts. Furthermore, the urban An. gambiae assessed here had a weaker preference for humans over cattle than reported by previous studies of the same species in rural contexts. Cattle keeping may therefore particularly limit the impact of human-targeted vector control interventions in Dar es Salaam and perhaps in other African towns and cities.

scholarly journals Reduced human-biting preferences of the African malaria vectors Anopheles arabiensis and Anopheles gambiae in an urban context: controlled, competitive host-preference experiments in Tanzania

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Yeromin P. Mlacha ◽  
Prosper P. Chaki ◽  
Athuman Muhili ◽  
Dennis J. Massue ◽  
Marcel Tanner ◽  
...  
Keyword(s):  
Vector Control ◽  
Anopheles Gambiae ◽  
Anopheles Arabiensis ◽  
Host Preference ◽  
Urban Setting ◽  
Sub Saharan Africa ◽  
Rural Setting ◽  
Malaria Vectors ◽  
Baited Traps ◽  
The Impact

Abstract Background Host preference is a critical determinant of human exposure to vector-borne infections and the impact of vector control interventions. Widespread use of long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) across sub-Saharan Africa, which protect humans against mosquitoes, may select for altered host preference traits of malaria vectors over the long term. Here, the host preferences of Anopheles arabiensis and Anopheles gambiae sensu stricto (s.s.) were experimentally assessed in the field, using direct host-preference assays in two distinct ecological settings in Tanzania. Methods Eight Ifakara Tent Trap (ITT), four baited with humans and four with bovine calves, were simultaneously used to catch malaria vectors in open field sites in urban and rural Tanzania. The numbers of mosquitoes collected in human-baited traps versus calf-baited traps were used to estimate human feeding preference for each site's vector species. Results The estimated proportion [95% confidence interval (CI)] of mosquitoes attacking humans rather than cattle was 0.60 [0.40, 0.77] for An. arabiensis in the rural setting and 0.61 [0.32, 0.85] for An. gambiae s.s. in the urban setting, indicating no preference for either host in both cases (P = 0.32 and 0.46, respectively) and no difference in preference between the two (Odds Ratio (OR) [95%] = 0.95 [0.30, 3.01], P = 0.924). However, only a quarter of An. arabiensis in the urban setting attacked humans (0.25 [0.09, 0.53]), indicating a preference for cattle that approached significance (P = 0.08). Indeed, urban An. arabiensis were less likely to attack humans rather than cattle when compared to the same species in the rural setting (OR [95%] = 0.21 [0.05, 0.91], P = 0.037). Conclusion Urban An. arabiensis had a stronger preference for cattle than the rural population and urban An. gambiae s.s. showed no clear preference for either humans or cattle. In the urban setting, both species exhibited stronger tendencies to attack cattle than previous studies of the same species in rural contexts. Cattle keeping may, therefore, particularly limit the impact of human-targeted vector control interventions in Dar es Salaam and perhaps in other African towns and cities.

scholarly journals Variation in sexual dimorphism and assortative mating do not predict genetic divergence in the sexually dimorphic Goodeid fish Girardinichthys multiradiatus

2012 ◽  
Vol 58 (3) ◽  
pp. 440-452 ◽  
Author(s):  
C. Macías Garcia ◽  
G. Smith ◽  
C. González Zuarth ◽  
J. A. Graves ◽  
M. G. Ritchie
Keyword(s):  
Sexual Selection ◽  
Gene Flow ◽  
Sexual Dimorphism ◽  
Assortative Mating ◽  
Genetic Divergence ◽  
Isolation By Distance ◽  
Morphological Differentiation ◽  
Morphological Differences ◽  
Or Gene ◽  
Male Morphology

Abstract Sexual dimorphism is often used as a proxy for the intensity of sexual selection in comparative studies of sexual selection and diversification. The Mexican Goodeinae are a group of livebearing freshwater fishes with large variation between species in sexual dimorphism in body shape. Previously we found an association between variation in morphological sexual dimorphism between species and the amount of gene flow within populations in the Goodeinae. Here we have examined if morphological differentiation within a single dimorphic species is related to assortative mating or gene flow between populations. In the Amarillo fish Girardinichthys multiradiatus studies have shown that exaggerated male fins are targets of female preferences. We find that populations of the species differ in the level of sexual dimorphism displayed due to faster evolution of differences in male than female morphology. However, this does not predict variation in assortative mating tests in the laboratory; in fact differences in male morphology are negatively correlated with assortative mating. Microsatellite markers reveal significant genetic differences between populations. However, gene flow is not predicted by either morphological differences or assortative mating. Rather, it demonstrates a pattern of isolation by distance with greater differentiation between watersheds. We discuss the caveats of predicting behavioural and genetic divergence from so-called proxies of sexual selection.

scholarly journals Determination of the discriminating concentration of chlorfenapyr (pyrrole) and Anopheles gambiae sensu lato susceptibility testing in preparation for distribution of Interceptor® G2 insecticide-treated nets

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Richard M. Oxborough ◽  
Aklilu Seyoum ◽  
Yemane Yihdego ◽  
Joseph Chabi ◽  
Francis Wat’senga ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
Large Scale ◽  
Resistance Mechanisms ◽  
Probit Analysis ◽  
Sub Saharan Africa ◽  
Malaria Vectors ◽  
Insecticide Treated Nets ◽  
Distributed Testing ◽  
The Difference ◽  
Sub Saharan

Abstract Background Following agricultural use and large-scale distribution of insecticide-treated nets (ITNs), malaria vector resistance to pyrethroids is widespread in sub-Saharan Africa. Interceptor® G2 is a new dual active ingredient (AI) ITN treated with alpha-cypermethrin and chlorfenapyr for the control of pyrethroid-resistant malaria vectors. In anticipation of these new nets being more widely distributed, testing was conducted to develop a chlorfenapyr susceptibility bioassay protocol and gather susceptibility information. Methods Bottle bioassay tests were conducted using five concentrations of chlorfenapyr at 12.5, 25, 50, 100, and 200 µg AI/bottle in 10 countries in sub-Saharan Africa using 13,639 wild-collected Anopheles gambiae sensu lato (s.l.) (56 vector populations per dose) and 4,494 pyrethroid-susceptible insectary mosquitoes from 8 colonized strains. In parallel, susceptibility tests were conducted using a provisional discriminating concentration of 100 µg AI/bottle in 16 countries using 23,422 wild-collected, pyrethroid-resistant An. gambiae s.l. (259 vector populations). Exposure time was 60 min, with mortality recorded at 24, 48 and 72 h after exposure. Results Median mortality rates (up to 72 h after exposure) of insectary colony mosquitoes was 100% at all five concentrations tested, but the lowest dose to kill all mosquitoes tested was 50 µg AI/bottle. The median 72-h mortality of wild An. gambiae s.l. in 10 countries was 71.5, 90.5, 96.5, 100, and 100% at concentrations of 12.5, 25, 50, 100, and 200 µg AI/bottle, respectively. Log-probit analysis of the five concentrations tested determined that the LC95 of wild An. gambiae s.l. was 67.9 µg AI/bottle (95% CI: 48.8–119.5). The discriminating concentration of 203.8 µg AI/bottle (95% CI: 146–359) was calculated by multiplying the LC95 by three. However, the difference in mortality between 100 and 200 µg AI/bottle was minimal and large-scale testing using 100 µg AI/bottle with wild An. gambiae s.l. in 16 countries showed that this concentration was generally suitable, with a median mortality rate of 100% at 72 h. Conclusions This study determined that 100 or 200 µg AI/bottle chlorfenapyr in bottle bioassays are suitable discriminating concentrations for monitoring susceptibility of wild An. gambiae s.l., using mortality recorded up to 72 h. Testing in 16 countries in sub-Saharan Africa demonstrated vector susceptibility to chlorfenapyr, including mosquitoes with multiple resistance mechanisms to pyrethroids.

scholarly journals Reticulate speciation and adaptive introgression in the Anopheles gambiae species complex

2014 ◽  
Author(s):  
Jacob Crawford ◽  
Michelle M. Riehle ◽  
Wamdaogo M. Guelbeogo ◽  
Awa Gneme ◽  
N'fale Sagnon ◽  
...  
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Anopheles Gambiae ◽  
X Chromosome ◽  
Species Complex ◽  
Sub Saharan Africa ◽  
Contemporary Gene Flow ◽  
Speciation Continuum ◽  
Primary Vector ◽  
Sub Saharan

Anopheles gambiae, the primary vector of human malaria in sub-Saharan Africa, exists as a series of ecologically specialized subgroups that are phylogenetically nested within the Anopheles gambiae species complex. These species and subgroups exhibit varying degrees of reproductive isolation, sometimes recognized as distinct subspecies. We have sequenced 32 complete genomes from field-captured individuals of Anopheles gambiae, Anopheles gambiae M form (recently named A. coluzzii), sister species A. arabiensis, and the recently discovered ?GOUNDRY? subgroup of A. gambiae that is highly susceptible to Plasmodium. Amidst a backdrop of strong reproductive isolation and adaptive differentiation, we find evidence for introgression of autosomal chromosomal regions among species and subgroups, some of which have facilitated adaptation. The X chromosome, however, is strongly differentiated among all species and subgroups, pointing to a disproportionately large effect of X chromosome genes in driving speciation among anophelines. Strikingly, we find that autosomal introgression has occurred from contemporary hybridization among A. gambiae and A. arabiensis despite strong divergence (~5? higher than autosomal divergence) and isolation on the X chromosome. We find a large region of the X chromosome that has swept to fixation in the GOUNDRY subgroup within the last 100 years, which may be an inversion that serves as a partial barrier to contemporary gene flow. We show that speciation with gene flow results in genomic mosaicism of divergence and introgression. Such a reticulate gene pool connecting vector species and subgroups across the speciation continuum has important implications for malaria control efforts.

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