Adaptive radiation and the role of ecology in neotropical cichlid fish divergence

南美洲和中美洲的河流拥有超过6000种淡水鱼，是地球上最多样化的鱼类。值得注意的是，人们对这种惊人的多样性的起源知之甚少。由该提案资助的研究将以慈鲷科为模型研究新热带鱼类的进化。我们以前和正在进行的工作表明，至少有一组美国慈鲷，Geophaginae，通过一个称为适应性辐射的过程多样化。这种快速的多样化可能与后来成为现代新热带区食土动物属的谱系入侵以前未被占据的生态位有关。基于这些结果，我们假设，其他群体的南美洲和中美洲慈鲷也可能多样化的适应性辐射。我们将通过描述所有新热带区慈鲷的进化历史来测试这一假设，重建它们进化中的过去事件，并揭示推动它们多样化的力量。此外，我们将通过研究来自南美洲的慈鲷属Geophagus的现代生态学和遗传学来评估生态压力在新热带区慈鲷物种形成中的重要性。了解南美洲和中美洲慈鲷的多样性起源将有助于了解热带淡水鱼起源的过程，特别是生物多样性。这项研究应该为未来了解新热带淡水鱼进化的努力铺平道路。该项目还将产生关于新热带慈鲷生态的广泛数据。这些信息应有助于养护工作，并揭示热带鱼及其环境可能易受无管制渔业、为农业和水电开发改变生境以及对水资源需求增加等形式的日益严重的威胁。

Rivers of South and Central America harbor more than 6000 species of freshwater fishes, the most diverse fish fauna on Earth. Remarkably, little is known about the origin of this astonishing diversity. Research funded by this proposal will study the evolution of Neotropical fishes using the family Cichlidae as a model. Our previous and ongoing work indicates that at least one group of American cichlids, the Geophaginae, diversified through a process known as adaptive radiation. This rapid diversification was probably associated with invasion of previously unoccupied ecological niches by lineages that would become the modern genera of Neotropical geophagines. Based on these results, we hypothesize that other groups of South and Central American cichlids may have also diversified by adaptive radiation. We will test this hypothesis by describing the evolutionary history of all Neotropical cichlids, reconstructing past events in their evolution and uncovering the forces that drove their diversification. Additionally, we will assess the importance of ecological pressures in Neotropical cichlid speciation by studying the modern ecology and genetics of the cichlid genus Geophagus from South America. Understanding how the diversity of South and Central American cichlids originated will shed light on the processes responsible for the origin of tropical freshwater fish in particular and biodiversity in general. This study should pave the way for future efforts to understand Neotropical freshwater fish evolution. The project also will generate extensive data on the ecology of Neotropical cichlids. This information should help conservation efforts and reveal potential vulnerabilities of tropical fishes and their environment to mounting threats in the form of unregulated fisheries, habitat modification for agriculture and hydroelectric development, and increasing demand on water resources.