Reproductive Isolation among Sympatric Molecular Forms of <i>An. gambiae</i> from Inland Areas of South-Eastern Senegal

<div><p>The <i>Anopheles gambiae</i> species complex includes at least seven morphologically indistinguishable species, one of which, <i>Anopheles gambiae sensu stricto,</i> is the primary mosquito vector responsible for the transmission of malaria across sub-Saharan Africa. Sympatric ecological diversification of <i>An. gambiae</i> s.s. is in progress within this complex, leading to the emergence of at least two incipient species (the M and S molecular forms now recognized as good species and named <i>An. coluzzii</i> and <i>An. gambiae</i> respectively) that show heterogeneous levels of divergence in most parts of Africa. However, this process seems to have broken down in coastal areas of West Africa at the extreme edge of the distribution. We undertook a longitudinal study to describe <i>An. gambiae</i> s.s. populations collected from two inland transects with different ecological characteristics in south-eastern Senegal. Analysis of samples collected from 20 sites across these two transects showed the M and S molecular forms coexisted at almost all sampled sites. Overall, similar hybridization rates (2.16% and 1.86%) were recorded in the two transects; sites with relatively high frequencies of M/S hybrids (up to 7%) were clustered toward the north-western part of both transects, often near urban settings. Estimated inbreeding indices for this putative speciation event varied spatially (range: 0.52–1), with hybridization rates being generally lower than expected under panmictic conditions. Such observations suggest substantial reproductive isolation between the M and S molecular forms, and further support the ongoing process of speciation in these inland areas. According to a recent reclassification of the <i>An. gambiae</i> complex, the M and S molecular forms from this zone correspond to <i>An. coluzzii</i> and <i>An. gambiae</i>, respectively. There is considerable evidence that these molecular forms differ in their behavioural and ecological characteristics. Detailed study of these characteristics will allow the development and implementation of better insect control strategies for combating malaria.</p></div

Spatial distribution of M/S hybrids frequencies.

<p>Spatial clustering trends (A). Significance of clustering was analysed using the Getis-Ord Gi* statistic <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104622#pone.0104622-Getis1" target="_blank">[19]</a>. (Z scores>0 indicates a clustering trend of high MS hybrids frequencies and Z scores<0 indicates a clustering trend of low MS hybrids frequencies. Significant Z scores (p<0.05) are in red. Moran scatter plots at site level (B). The names of the sites with large contributions to autocorrelation are displayed.</p

Characteristics of clusters classes.

<p>MS = MS hybrids frequencies.</p><p>For the different clusters, means with different letters are significantly different (p<0.05).</p

Main characteristics of the study sites.

<p>Main characteristics of the study sites.</p

Frequencies of species within <i>Anopheles gambiae</i> complex and of molecular forms of <i>Anopheles gambiae</i> s.s. in the two transects.

<p>% = Percentage, Obs. = observed, Exp. = expected, <i>Fis</i> = inbreeding coefficient calculated according to Weir and Cockerham <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104622#pone.0104622-Weir1" target="_blank">[37]</a>, <i>Fis</i><0 indicate an excess of heterozygotes, <i>Fis</i>>0 denote heterozygotes deficiency, *no significant deviation from Hardy–Weinberg expectations (P>0.05).</p

Variations of the mean frequencies of <i>An</i>. <i>arabiensis</i> and <i>An</i>. <i>gambiae</i>.

<p>A: between transects, bars represent standard errors. B: within villages in each transect (Transect 1 = T1, Transect 2 = T2).</p

Piper kazura Ohwi

原著和名: フウトウカヅラ科名: コショウ科 = Piperaceae採集地: 東京都 八丈島 (伊豆 八丈島)採集日: 1970/6/10採集者: 萩庭丈壽整理番号: JH008949国立科学博物館整理番号: TNS-VS-95894

Additional file 6: Table S6. of Investigating molecular basis of lambda-cyhalothrin resistance in an Anopheles funestus population from Senegal

Detoxification genes commonly under expressed in the comparisons R-S_L, C-S (FC ≥ 2) and R-C_L (FC ≥ 1.5) P ≤ 0.05. (DOCX 54 kb

Additional file 10: Figure S1. of Investigating molecular basis of lambda-cyhalothrin resistance in an Anopheles funestus population from Senegal

Region flanking the kdr codon 1014 (TTA, indicated in red), showing no variation in wild type An. funestus from Gankette Balla. (TIF 1521 kb

Additional file 1: Table S1. of Investigating molecular basis of lambda-cyhalothrin resistance in an Anopheles funestus population from Senegal

List of primers used in this study. (DOCX 72 kb