Data from: Continental diversification of an African catfish radiation (Mochokidae: Synodontis)

Despite African rivers containing high species diversity,
continental-scale studies investigating the mechanisms generating
biological diversity of African riverine faunas are limited compared to
lacustrine systems.To investigate the build up of diversity in a tropical
aquatic continental radiation, we test different models of lineage
diversification and reconstruct the biogeographic history in a
species-rich siluriform genus, Synodontis (~130 species), with a broad
distribution across all major tropical African drainage basins. The
resulting robust species-level phylogeny (~60% complete, based on a
multigene dataset) exhibits a near constant rate of lineage accumulation
throughout the mid-Cenozoic to Recent, irrespective of missing species and
despite the changing environmental conditions that were prevalent during
this time period. This pattern contrasts with the findings for
species-level diversification of large clades that commonly show an early
burst of cladogenesis followed by declining rates through time. The
identification of distinct biogeographic cladesdemonstrates acorrelation
between river hydrology and cladogenesis, although there is evidence of
recent repeat dispersal into the southern range of the focal group.We
conclude that diverse freshwater fish radiations with tropical continental
distributions represent important organisms to test hypotheses of
diversification and investigate the effects of palaeo landscapes and
climates on present day biodiversity.

尽管非洲河流拥有极高的物种多样性，但与湖泊系统相比，针对非洲河流动物群生物多样性形成机制的大陆尺度研究仍较为有限。为探究热带水生大陆辐射中多样性的形成过程，我们对不同的谱系分化模型进行了检验，并重建了物种丰富的鲇形目（Siluriform）属——歧须鮠属（Synodontis，约130种）的生物地理历史；该属广泛分布于非洲所有主要热带流域。基于多基因数据集构建的可靠物种级系统发育树（完成度约60%）显示，从新生代中期到现代，谱系积累速率近乎恒定——无论是否存在物种缺失，也无视该时期普遍存在的环境条件变化。这一模式与大型支系物种级分化的研究结果形成对比——后者通常表现为早期分支发生（cladogenesis）爆发，随后分化速率随时间推移逐渐下降。我们得出结论：具有热带大陆分布特征的多样淡水鱼类辐射类群，是检验分化假说及探究古景观与古气候对现代生物多样性影响的重要研究对象。