Phylogenetics and Historical Biogeography of Otocinclus

本项目将进行为期三年的系统分类学、自然历史和耳卷鲶鱼的生物地理学研究。这一组大约有20个物种，属于新热带地区最大的淡水鱼群之一，Loricariidae科，包括600多种。这些鱼类是巴西东南部大西洋沿岸地区鱼类区系的重要组成部分，该地区包括大西洋沿岸森林的遗迹，已被确定为生物多样性高的地区，面临严重的退化威胁。对这一特殊鱼类群体的研究的相关性在于它们对理解复杂的历史过程的贡献，这些历史过程塑造了居住在巴西大西洋沿岸地区的生物地理。一些固有的生物学特性，以及之前对该群体的研究，对耳跖目的研究对于实现这些更广泛的目标具有特殊的意义。这类鱼类的代表目前广泛分布于整个南美洲，在每一个主要的河流流域都有一种或多种。它们的体积小，加上分散能力低和地理分布广泛，使它们易于进行这种生物地理分析。对耳含目物种之间关系的了解，加上对大西洋沿岸地区其他动物和植物群体的类似数据，将为重建这一特定地区的生物地理历史提供基础数据，并寻求造成今天观察到的生物群体分布特性的共同因果因素。这些信息可以用来制定保护和管理策略。尽管它们很重要，但人们对这些鱼的基本生物学和分类方面知之甚少；在了解大西洋沿岸地区的生物地理学取得进展之前，必须修订这一类群的系统分类，描述和说明新物种，确定它们之间的相互关系，并确定目前的分布。对其形状、颜色模式和形态特征的分析将用于确定耳蛤属的分类界限。将对大西洋沿岸两个鲜为人知的地区和邻近的河流系统进行考察，对以前未记载的物种进行取样，并确定它们的分布。将在北美和南美的主要博物馆进行一般鱼类学收集和标本存放，为继续研究奠定物质基础。以实验室为基础的形态学研究将用于重建耳属物种之间的关系。然后，这个项目将为建立一个全面的数据集提供一个额外的组成部分，用于测试新热带地区相互竞争的生物地理学假设。

This project will conduct a three year study of the systematics and taxonomy, natural history, and biogeography of the catfishes of the genus Otocinclus. This group of approximately 20 species belongs to one of the largest radiations of freshwater fishes in the Neotropics, the family Loricariidae, which includes over 600 species. These fishes are an important component of the fish fauna of the Atlantic coastal region of southeast Brazil, which includes remnants of the Atlantic Coastal Forest and has been identified as a region of high biodiversity under severe threat of degradation. Relevance of the study of this particular group of fishes lies in their contribution toward understanding the complex historical processes which have shaped the biogeography of organisms inhabiting the Atlantic coastal region of Brazil. Several inherent biological properties, as well as previous work on the group, lend particular significance to study of Otocinclus for achieving these broader goals. Representatives of this group of fishes are presently widely distributed throughout South America, with one or more species occurring in every major river drainage basin. Their small size, coupled with low capabilities for dispersal and wide geographic distribution, predispose them for this kind of biogeographic analysis. Knowledge of the relationships among species of Otocinclus, coupled with similar data for other groups of animals and plants having representatives in the Atlantic coastal region, will provide the basic data for reconstructing the biogeographic history of this particular region and seeking the common causal factors responsible for producing the distributional properties of groups of organisms observed today. This information can then be used to formulate conservation and management strategies. Despite their importance, aspects of the basic biology and taxonomy of these fishes are poorly known; the systematics of this group must be revised, new species described and illustrated, their inter-relationships determined, and present distributions defined before progress in understanding the biogeography of the Atlantic coastal region can be made. Analyses of shape, coloration pattern, and morphological characteristics will be used to determine the taxonomic limits to the species of Otocinclus. Expeditions to two poorly known areas of the Atlantic coastal and neighboring river systems will be undertaken to sample previously undocumented species and to define their distributions. General ichthyological collections will be made and specimens deposited in major museums in both North and South America, forming the material basis for continued study. Laboratory based morphological studies will be used to reconstruct the relationships among Otocinclus species. This project will then provide one additional component toward building a comprehensive dataset for testing competing biogeographic hypotheses in the Neotropical region.