Data from: Spatio-temporal genetic structure of Anopheles gambiae in the Northwestern Lake Victoria Basin, Uganda: implications for genetic control trials in malaria endemic regions

Background: Understanding population genetic structure in the malaria vector Anopheles gambiae (s.s.) is crucial to inform genetic control and manage insecticide resistance. Unfortunately, species characteristics such as high nucleotide diversity, large effective population size, recent range expansion, and high dispersal ability complicate the inference of genetic structure across its range in sub-Saharan Africa. The ocean, along with the Great Rift Valley, is one of the few recognized barriers to gene flow in this species, but the effect of inland lakes, which could be useful sites for initial testing of genetic control strategies, is relatively understudied. Here we examine Lake Victoria as a barrier between the Ugandan mainland and the Ssese Islands, which lie up to 60 km offshore. We use mitochondrial DNA (mtDNA) from populations sampled in 2002, 2012 and 2015, and perform Bayesian cluster analysis on mtDNA combined with microsatellite data previously generated from the same 2002 mosquito DNA samples.

Results: Hierarchical analysis of molecular variance and Bayesian clustering support significant differentiation between the mainland and lacustrine islands. In an mtDNA haplotype network constructed from this and previous data, haplotypes are shared even between localities separated by the Rift Valley, a result that more likely reflects retention of shared ancestral polymorphism than contemporary gene flow.

Conclusions: The relative genetic isolation of An. gambiae on the Ssese Islands, their small size, level terrain and ease of access from the mainland, the relative simplicity of the vectorial system, and the prevalence of malaria, are all attributes that recommend these islands as possible sites for the testing of genetic control strategies.

研究背景：阐明疟疾媒介狭义冈比亚按蚊（Anopheles gambiae s.s.）的种群遗传结构，可为遗传防控策略制定及杀虫剂抗性管理提供关键依据。然而，该物种兼具高核苷酸多样性、大有效种群规模、近期分布范围扩张以及强扩散能力等特征，增加了撒哈拉以南非洲全域范围内其遗传结构推断的难度。海洋与东非大裂谷是目前公认的少数几处该物种种间基因流障碍之一，但内陆湖泊作为潜在的遗传防控策略初期测试位点，其对基因流的影响尚未得到充分研究。本研究以维多利亚湖为研究对象，探讨其作为乌干达本土与离岸最远达60公里的塞塞群岛之间的地理屏障的作用。我们使用2002年、2012年及2015年采集种群的线粒体DNA（mitochondrial DNA，下文简称mtDNA），并结合此前从同一批2002年蚊类DNA样本中获得的微卫星数据，对mtDNA开展贝叶斯聚类分析。
研究结果：分层分子方差分析与贝叶斯聚类结果均显示，本土与湖岛种群间存在显著遗传分化。基于本次及既往数据构建的mtDNA单倍型网络显示，即便在被东非大裂谷分隔的采样点之间也存在共享单倍型，该结果更可能反映的是共享祖先多态性的保留，而非当代基因流。
研究结论：塞塞群岛上的冈比亚按蚊存在相对的遗传隔离，加之该群岛面积较小、地形平坦且易于从本土抵达，其媒介传播系统相对简易，且当地疟疾流行率较高，这些特征均表明塞塞群岛可作为遗传防控策略测试的潜在位点。