The Study of Gene Exchange During Recent Speciation Events among Cichlids of Lake Malawi

世界上有一千多种鱼类，但令人惊讶的是，这种多样性大多出现在非洲大湖、马拉维(尼亚萨)、坦噶尼喀湖和维多利亚。从进化的角度来看，这些湖泊的年龄并不算大，生物学家们对每个湖泊中存在的数百种独特的慈济鱼物种是如何迅速崛起感到困惑的。传统的物种形成模型假设，独立的物种首先是不交换基因的孤立种群。然而，一个重要的替代模式可能适用于没有尖锐的迁徙障碍的地方，那就是物种的出现不需要种群分离。这个模型包括新形成物种之间的基因交换，以及导致分化的自然选择。这是一个有趣的模型，但很难测试。在这个项目中，研究人员将通过应用一种新开发的遗传程序来测试该模型，该程序用于检测来自马拉维湖的几个叶蝉物种之间最近的基因交换。马拉维湖的Cichlids已经成为许多研究人员研究物种形成的模式系统。然而，这里的关键问题，就像最近形成的物种的其他情况一样，是自然选择直接导致了这种分化，还是物种是作为完全独立的种群出现的，并且分开了。这个问题对于理解生物多样性是如何产生的至关重要。

There are over one thousand species of fish in the family Cichlidae (Cichlids) throughout the world, but surprisingly most of this diversity occurs in the great African lakes, Malawi (Nyasa), Tanganyika, and Victoria. These lakes are not of great age, in evolutionary terms, and biologists are puzzled over how the hundreds of unique Cichlid species, that exist in each of these lakes, could have arisen quickly. The traditional model of species formation assumes that separate species first begin as isolated populations that do not exchange genes. However, an important alternative model that could apply where there are not sharp barriers to migration, is that species arise without population separation. This model includes gene exchange between newly forming species, as well as natural selection acting to cause divergence. It is an interesting model, but difficult to test. In this project, researchers will test the model by applying a newly developed genetic procedure for detecting recent gene exchange between several Cichlid species from Lake Malawi. The Cichlids of Lake Malawi have become a model system for many researchers studying speciation. Yet the critical question here, as in other cases of recently formed species, is whether natural selection has caused the divergence directly, or whether species arise as completely separate populations that diverge separately. This question is fundamental to the understanding of how biological diversity arises.