Dissertation Research: Phylogenetic Relationships of the Major Lineages of Characiform Fishes

鱼目特征包括生活在非洲、中美洲和南美洲的最重要的淡水鱼群。人们对它们进行了广泛的研究，因为它们作为食物和水族馆资源具有重要的经济意义（例如，“tetras”），还因为它们对多种水生环境具有非凡的适应性，包括臭名昭著的食人鱼的捕食习惯。然而，特征鱼类主要科之间的进化关系尚不清楚，单靠形态特征对解决问题没有多大帮助。指导教师Axel Meyer将协助研究生Guillermo Orti对主要特征群体代表性样本的线粒体DNA变异进行广泛的分子系统调查。鱼种间线粒体DNA突变的数量和种类的差异反映了鱼种间谱系关系的相对程度，从而为推测这些谱系的系统发育提供了数据。深入了解这种种类丰富的鱼类的进化史，将有助于理解冈瓦纳大陆地质解体后非洲和南美动物群之间的地理多样性。

The fish order Characiformes comprises the most important group of freshwater fishes living in Africa and in Central and South America. They have been studied extensively because of their economic importance as food and as aquarium resources (for example, the "tetras"), and because of their remarkable adaptations to numerous kinds of aquatic environments, including the infamous predatory habits of the piranhas. However, the evolutionary relationships among the major families of characiform fishes are poorly understood, and morphological characters alone promise little help in resolving the matter. Faculty advisor Axel Meyer will assist graduate student Guillermo Orti in an extensive molecular systematic survey of mitochondrial DNA variation in representative samples of the major characiform groups. The amount and kind of mutational differences in mitochondrial DNA between fish species indicate relative degree of genealogical relationship, and thus provide data to infer the phylogeny of these lineages. Insight into the evolutionary history of this species-rich group of fishes will in turn help in understanding the geographical diversification between African and South American faunas following the geological breakup of Gondwana.