GENE EXCHANGE BETWEEN AFRICAN MALARIA VECTORS

从医学角度来看，冈比亚按蚊复合体可以说是最重要的昆虫群；它是非洲疟疾的主要媒介，因此也是全世界的主要媒介。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，以及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通过在自然界中杂交来交换遗传物质，这种现象被称为导入。但似乎并不是物种基因组的所有部分都能同样地跨越物种边界。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是造成不育障碍的原因。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实现。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比例尺作图。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存在长达20代。第二个项目涉及到内向的动力。特别是，将讨论这种渗透是一种古老的现象还是最近正在进行的过程的问题。这个项目将涉及染色体倒置中的DNA序列的检查，即第二条染色体左臂(2LA)的“a”倒置，对于这种倒置，有很好的证据表明物种间的转移。这一倒置的历史将利用系统发育程序和对与数据最一致的海侵事件数量的统计分析来确定。了解世界上疟疾的两个最重要的媒介(An.冈比亚亚纲和An.交换基因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.