BACKGROUND Distichodus is a clade of tropical freshwater fishes currently comprising 25 named species distributed continent-wide throughout the Nilo-Sudan and most Sub-Saharan drainages. This study investigates the phylogenetic relationships, timing of diversification, and biogeographic history of the genus from a taxonomically comprehensive mutilocus dataset analyzed using Maximum Likelihood and Bayesian methods of phylogenetic inference, coalescence-based species-tree estimation, divergence time estimation, and inference of geographic range evolution. RESULTS Analyses of comparative DNA sequence data in a phylogenetic context reveal the existence of two major clades of similar species-level diversity and provide support for the monophyletic status of most sampled species. Biogeographic reconstruction on a time-scaled phylogeny suggest that the origins of the genus date back to the late Oligocene and that current geographic distributions are the result of a Congo Basin origin followed by dispersal and range expansion into adjacent ichthyofaunal provinces at different times during the evolutionary history of the group. CONCLUSIONS We present the most comprehensive phylogenetic, chronological, and biogeographic treatment yet conducted for the genus. The few instances of species paraphyly (D. teugelsi, D. fasciolatus) revealed by the resulting phylogenies are likely a consequence of post-divergence introgressive hybridization and/or incomplete lineage sorting due to recent speciation. Historical biogeographic findings are both in agreement and conflict with previous studies of other continent-wide African freshwater fish genera, suggesting a complex scenario for the assemblage of Africa's continental ichthyofaunal communities.

中文翻译：

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非洲淡水鱼属 Distichodus（Characiformes：Distichodontidae）多样化的模式和时间。


背景 Distichodus 是热带淡水鱼类的一个分支，目前包括 25 个命名物种，分布在尼罗-苏丹和大多数撒哈拉以南流域的整个大陆。本研究利用系统发育推断的最大似然法和贝叶斯方法、基于合并的物种树估计、分歧时间估计和地理推断，从分类学上全面的多位点数据集研究了该属的系统发育关系、多样化的时间和生物地理历史。范围演化。结果 在系统发育背景下对比较 DNA 序列数据的分析揭示了两个具有相似物种水平多样性的主要分支的存在，并为大多数样本物种的单系状态提供了支持。时间尺度系统发育的生物地理学重建表明，该属的起源可以追溯到渐新世晚期，目前的地理分布是刚果盆地起源的结果，随后在进化过程中的不同时间扩散和范围扩展到邻近的鱼类动物区系省份。集团的历史。结论 我们提出了迄今为止对该属进行的最全面的系统发育、年代学和生物地理学处理。由此产生的系统发育揭示的少数物种并系发育实例（D. teugelsi、D. fasciolatus）可能是由于最近的物种形成导致的分歧后渐渗杂交和/或不完整的谱系分类的结果。历史生物地理学研究结果与之前对非洲大陆其他淡水鱼属的研究既一致又冲突，表明非洲大陆鱼类动物群落的组合存在着复杂的情况。