Matthews S D, Meehan L J, Onyabe D Y, Vineis J, Nock I, Ndams I, Conn J E
Department of Biomedical Sciences, School of Public Health, University at Albany, State University of New York, New York, U.S.A.
Med Vet Entomol. 2007 Dec;21(4):358-69. doi: 10.1111/j.1365-2915.2007.00703.x.
Anopheles gambiae Giles s.s. and Anopheles arabiensis Patton (Diptera: Culicidae) are major vectors of malaria in Nigeria. We used 1115 bp of the mitochondrial COI gene to assess their population genetic structures based on samples from across Nigeria (n = 199). The mtDNA neighbour-joining tree, based on F(ST) estimates, separated An. gambiae M and S forms, except that samples of An. gambiae M from Calabar clustered with all the An. gambiae S form. Anopheles arabiensis and An. gambiae could be combined into a single star-shaped, parsimonious haplotype network, and shared three haplotypes. Haplotype diversity values were high in An. arabiensis and An. gambiae S, and intermediate in An. gambiae M; all nucleotide diversities were relatively low. Taken together, patterns of haplotype diversity, the star-like genealogy of haplotypes, five of seven significant neutrality tests, and the violation of the isolation-by-distance model indicate population expansion in An. arabiensis and An. gambiae S, but the signal was weak in An. gambiae M. Selection is supported as an important factor shaping genetic structure in An. gambiae in Nigeria. There were two geographical subdivisions in An. arabiensis: one included all southern localities and all but two central localities; the other included all northern and two central localities. Re-analysing an earlier microsatellite dataset of An. arabiensis using a Bayesian method determined that there were two distinctive clusters, northern and southern, that were fairly congruent with the mtDNA subdivisions. There was a trend towards decreasing genetic diversity in An. arabiensis from the northern savannah to the southern rainforest that corroborated previous data from microsatellites and polytene chromosomes.
冈比亚按蚊指名亚种（Anopheles gambiae Giles s.s.）和阿拉伯按蚊（Anopheles arabiensis Patton）（双翅目：蚊科）是尼日利亚疟疾的主要传播媒介。我们利用线粒体COI基因的1115个碱基对，基于来自尼日利亚各地的样本（n = 199）评估它们的种群遗传结构。基于F(ST)估计值构建的线粒体DNA邻接树，将冈比亚按蚊的M型和S型区分开来，但来自卡拉巴尔的冈比亚按蚊M型样本与所有冈比亚按蚊S型样本聚类在一起。阿拉伯按蚊和冈比亚按蚊可以合并成一个单一的星形简约单倍型网络，并且共享三种单倍型。阿拉伯按蚊和冈比亚按蚊S型的单倍型多样性值较高，冈比亚按蚊M型的单倍型多样性值处于中等水平；所有核苷酸多样性相对较低。综合来看，单倍型多样性模式、单倍型的星形谱系、七个显著中性检验中的五个以及对距离隔离模型的违反，表明阿拉伯按蚊和冈比亚按蚊S型存在种群扩张，但在冈比亚按蚊M型中信号较弱。选择被认为是塑造尼日利亚冈比亚按蚊遗传结构的一个重要因素。阿拉伯按蚊存在两个地理亚群：一个包括所有南部地区以及除两个中部地区之外的所有中部地区；另一个包括所有北部地区和两个中部地区。使用贝叶斯方法重新分析早期的阿拉伯按蚊微卫星数据集，确定存在两个不同的聚类，即北部和南部聚类，这与线粒体DNA亚群相当一致。从北部稀树草原到南部雨林，阿拉伯按蚊的遗传多样性有降低的趋势，这与之前来自微卫星和多线染色体的数据相印证。
