Obbard D J, Linton Y-M, Jiggins F M, Yan G, Little T J
Institute of Evolutionary Biology, University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh, UK.
Mol Ecol. 2007 Aug;16(16):3497-510. doi: 10.1111/j.1365-294X.2007.03395.x.
Anopheles mosquitoes are the primary vectors for malaria in Africa, transmitting the disease to more than 100 million people annually. Recent functional studies have revealed mosquito genes that are crucial for Plasmodium development, but there is presently little understanding of which genes mediate vector competence in the wild, or evolve in response to parasite-mediated selection. Here, we use population genetic approaches to study the strength and mode of natural selection on a suite of mosquito immune system genes, CTL4, CTLMA2, LRIM1, and APL2 (LRRD7), which have been shown to affect Plasmodium development in functional studies. We sampled these genes from two African populations of An. gambiae s.s., along with several closely related species, and conclude that there is no evidence for either strong directional or balancing selection on these genes. We highlight a number of challenges that need to be met in order to apply population genetic tests for selection in Anopheles mosquitoes; in particular the dearth of suitable outgroup species and the potential difficulties that arise when working within a closely-related species complex.
按蚊是非洲疟疾的主要传播媒介,每年将这种疾病传播给超过1亿人。最近的功能研究揭示了对疟原虫发育至关重要的蚊子基因,但目前对于哪些基因在野外介导媒介能力,或因寄生虫介导的选择而进化,了解甚少。在这里,我们使用群体遗传学方法来研究一组蚊子免疫系统基因CTL4、CTLMA2、LRIM1和APL2(LRRD7)上自然选择的强度和模式,这些基因在功能研究中已被证明会影响疟原虫的发育。我们从冈比亚按蚊的两个非洲种群以及几个密切相关的物种中对这些基因进行了采样,并得出结论,没有证据表明对这些基因存在强烈的定向选择或平衡选择。我们强调了在按蚊中应用群体遗传学选择测试需要克服的一些挑战;特别是合适的外类群物种的缺乏,以及在一个密切相关的物种复合体中工作时可能出现的潜在困难。