Instituto de Biología, Universidad Nacional Autónoma de México, Circuito Zona Deportiva 53, Ciudad Universitaria, 04510 Coyoacán, Ciudad de México, Mexico.
Department of Ichthyology, American Museum of Natural History, Central Park West at 79th Street, New York, NY, 10024, USA.
BMC Evol Biol. 2020 Apr 26;20(1):48. doi: 10.1186/s12862-020-01615-6.
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.
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.
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.
Distichodus 是一个热带淡水鱼类群，目前包含 25 个命名物种，分布在整个尼罗河流域和撒哈拉以南的大多数流域。本研究从分类学上全面的多基因座数据集进行最大似然法和贝叶斯系统发育推断、基于合并的种系发生树估计、分歧时间估计和地理范围进化推断，研究了该属的系统发育关系、多样化时间和生物地理历史。
在系统发育背景下对比较 DNA 序列数据的分析揭示了两个主要分支的存在，具有相似的物种多样性，并为大多数采样物种的单系性提供了支持。时间尺度系统发育上的生物地理重建表明，该属的起源可以追溯到晚渐新世，目前的地理分布是刚果盆地起源的结果，随后在该群体的进化历史的不同时期，向相邻的鱼类区系进行扩散和范围扩张。
我们提出了迄今为止对该属进行的最全面的系统发育、时间和生物地理处理。少数物种的并系现象（D.teugelsi、D.fasciolatus）可能是由于种间杂交和/或由于最近的物种形成而导致的不完全谱系分选造成的。历史生物地理发现与其他非洲大陆淡水鱼类属的先前研究既一致又冲突，表明非洲大陆鱼类群落的集合存在复杂的情况。
