Investigating the role of hybridization in the evolution of the genus Corydoras

两个物种交配并产生后代的杂交越来越被认为在新物种甚至物种群体的进化中发挥着重要作用。它与夏威夷蟋蟀、贝加尔湖雕像和非洲湖泊慈济鱼(三次辐射，每种数百种)的进化有关，仅举三例。在这项研究中，我将调查杂交在一群南美叉尾鱼进化中所起的作用，其中许多在进化史上的某个时候经历了DNA翻倍。我将确定线粒体DNA基因(仅从母亲那里遗传)和核基因的序列，其中一个拷贝是从父亲和母亲那里继承的。然后将利用这些DNA序列中的差异来确定物种之间的关系。在已经发生杂交的物种中，来自两个亲本物种的DNA序列应该存在于核基因中，这可能允许确定哪些物种已经杂交产生新物种的进化历史。微卫星标记还将用于调查每个物种的最低倍性水平，以确定每个物种的基因组在其进化史上是否翻了一番。

Hybridization, where two species mate and produce offspring is being increasingly recognised as having an important role in the evolution of new species and even groups of species. It has been implicated in the evolution of the Hawaiian crickets, the Lake Baikal sculpins and the African lacustrine cichlids (three radiations of several hundred species each) to name but three. In this study I will investigate the role hybridization has played in the evolution of a group of South American catfish, many of which have undergone a doubling of their DNA at some point in their evolutionary history. I will determine the sequences of mitochondrial DNA genes (which are inherited solely from the mother), and nuclear genes, for which a copy is inherited from the father and the mother. The relationships between species will then be determined using differences in these DNA sequences. In species in which hybridization has occurred, DNA sequences from both the parental species should be present at nuclear genes, and this may allow the evolutionary history of which species have hybridised to produce new species to be determined. Microsatellite markers will also be used to investigate the minimum ploidy level of each taxa in order to determine whether the genome of each species has been doubled in its evolutionary history.