Genetic differentiation in the African malaria vector, Anopheles gambiae s.s., and the problem of taxonomic status.
Genetic differentiation in the African malaria vector, Anopheles gambiae s.s., and the problem of taxonomic status.
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非洲疟疾媒介冈比亚按蚊的遗传分化和分类地位问题。
DOI：
10.1093/genetics/161.4.1561
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发表时间：
2002
期刊：
影响因子：
3.3
通讯作者：
Caccone,Adalgisa
中科院分区：
文献类型：
--
作者：
Gentile,Gabriele;DellaTorre,Alessandra;Maegga,Bertha;Powell,JeffreyR;Caccone,Adalgisa
冈比亚复合按蚊（Anopheles gambiaecomplex）的7个种中，A.冈比亚公司是传播最广也是最重要的疟疾传播媒介。越来越清楚的是，在西非的部分地区，这种名义上的物种不是一个单一的panmictic单位。我们发现，内部转录间隔区（ITS）的X-连锁rDNA有两个不同的序列与三个固定的核苷酸差异，我们没有检测到杂合子在这三个网站，即使在两个ITS类型的同域区。该区域的基因间间隔区（IGS）也显示出两个不同的序列，它们与不同的ITS等位基因几乎完全连锁不平衡。我们将这两种类型分别命名为S/I型和M/II型。这些rDNA类型至少部分地对应于先前识别的染色体形式。在这里，我们扩大了地理范围的采样到251个人从38个种群。在西非以外，一个单一的rDNA类型，S/I型，对应于草原染色体形式。在西非，这两种类型往往在一个地方样本中发现。为了了解这些发现是否可能是由于rDNA区域的异常行为，我们对46 A的相同区域进行了测序。arabiensis，同域同胞种。没有观察到这种明显的不连续性。在一条染色体臂（2 R）上的常染色体倒位，在2L上的杀虫剂抗性基因，以及这个单一的X连锁区域表明A.然而，对基因组其他区域的相当广泛的研究未能揭示遗传不连续性。显然，不完全的遗传隔离存在于这个单一的名义物种。
Of the seven recognized species of theAnopheles gambiaecomplex,A. gambiaes.s. is the most widespread and most important vector of malaria. It is becoming clear that, in parts of West Africa, this nominal species is not a single panmictic unit. We found that the internal transcribed spacer (ITS) of the X-linked rDNA has two distinct sequences with three fixed nucleotide differences; we detected no heterozygotes at these three sites, even in areas of sympatry of the two ITS types. The intergenic spacer (IGS) of this region also displays two distinct sequences that are in almost complete linkage disequilibrium with the distinct ITS alleles. We have designated these two types as S/type I and M/type II. These rDNA types correspond at least partly to the previously recognized chromosomal forms. Here we expand the geographic range of sampling to 251 individuals from 38 populations. Outside of West Africa, a single rDNA type, S/type I, corresponds to the Savanna chromosomal form. In West Africa, both types are often found in a single local sample. To understand if these findings might be due to unusual behavior of the rDNA region, we sequenced the same region for 46A. arabiensis, a sympatric sibling species. No such distinct discontinuity was observed for this species. Autosomal inversions in one chromosome arm (2R), an insecticide resistance gene on 2L, and this single X-linked region indicate at least two genetically differentiated subpopulations ofA. gambiae.Yet, rather extensive studies of other regions of the genome have failed to reveal genetic discontinuity. Evidently, incomplete genetic isolation exists within this single nominal species.