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

鱼形目包括生活在非洲和中美洲和南美洲的最重要的淡水鱼群体。它们被广泛研究，是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，“河豚”)，而且它们对多种水生环境，包括臭名昭著的食人鱼的捕食习性有着非凡的适应能力。然而，人们对鱼类主要家族之间的进化关系知之甚少，仅凭形态特征对解决这一问题几乎没有帮助。教师顾问Axel Meyer将协助研究生Guillermo Orti对主要特征群体的代表性样本中的线粒体DNA变异进行广泛的分子系统调查。鱼类之间线粒体DNA突变的数量和种类的差异表明了它们之间的亲缘关系的相对程度，从而为推测这些谱系的系统发育提供了数据。洞察这一物种丰富的鱼类群体的进化史，反过来将有助于理解冈瓦那地质解体后非洲和南美洲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.