GENE EXCHANGE BETWEEN AFRICAN MALARIA VECTORS

从医学的角度来看，冈比亚按蚊复合体可以说是最重要的昆虫群体;它是非洲疟疾的主要媒介，因此也是世界疟疾的主要媒介。这些项目的目标是了解该群体的进化遗传学;这包括了解物种之间不育障碍的遗传基础和物种之间基因交换的动态。先前的研究表明，两个密切相关的物种可能会通过自然杂交来交换遗传物质，这种现象被称为基因渗入。但似乎不是一个物种基因组的所有部分都同样能够跨越物种边界。利用遗传标记（微卫星），我们打算直接测试基因组的哪些部分负责不育障碍。这将通过进行种间杂交，将可育的杂交雌性与每个物种的雄性回交，评估回交后代的生殖状态，并对至少24个均匀分布在基因组中的微卫星进行基因分型来完成。当确定了导致不育的区域时，将通过增加微卫星标记的密度来进行更精细的绘图。在一项相关的研究中，我们将确定基因组的哪些部分能够在自由繁殖的回交群体中持续长达20代。第二个项目涉及基因渗入的动力学。特别是，渗入是一个古老的现象还是一个最近的，正在进行的过程的问题将得到解决。该项目将涉及检查染色体倒位中的DNA序列，即第二条染色体（2La）左臂的“a”倒位，这是种间转移的良好证据。将使用系统发育程序和与数据最一致的渐渗事件数量的统计分析来确定该倒位的历史。了解世界上两种最重要的疟疾病媒是否（一个。gambiae和An.阿拉伯种之间的基因交换对于针对这些物种的控制措施至关重要。

From a medical perspective, the Anopheles gambiae complex is arguably the most important group of insects; it is the primary vector of malaria in Africa, and hence the world. The goal of these projects is to understand the evolutionary genetics of the group; this includes understanding the genetic basis of sterility barriers between species and the dynamics of gene exchange between species. Previous research has indicated that two closely related species may be exchanging genetic material by hybridizing in nature, the phenomenon known as introgression. But it appears that not all parts of a species genome are equally able to cross species boundaries. Using genetic markers (microsatellites) we intend to directly test which parts of the genome are responsible for sterility barriers. This will be done by making interspecific crosses, backcrossing fertile hybrid females to males of each species, assessing the reproductive status of the backcross progeny, and genotyping them for at least 24 microsatellites spread evenly across the genome. When regions responsible for sterility are identified, finer scale mapping will be done by increasing the density of microsatellite markers. In a related study, we will determine which parts of the genome are able to persist in freely breeding backcross populations for up to twenty generations. The second project concerns the dynamics of introgression. In particular, the question of whether the introgression is an ancient phenomenon or a recent, ongoing process will be addressed. This project will involve examination of DNA sequences in a chromosome inversion, the "a" inversion of the left arm of the second chromosome (2La), for which there is good evidence of interspecies transfer. The history of this inversion will be determined using phylogenetic procedures and statistical analysis for the number on introgression events most consistent with the data. Understanding whether the two most important vectors of malaria in the world (An. gambiae and An. arabiensis) are exchanging genes is vitally important to control measures aimed at these species.