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，但相较于湖泊生态系统，针对非洲河流生物区系物种多样性形成机制开展的大陆尺度研究仍较为匮乏。为探究热带水生大陆辐射类群的多样性形成过程，本研究以物种丰富的鲇形目（Siluriformes）歧须鮠属（Synodontis，约130种）为研究对象——该属物种广泛分布于非洲所有主要热带河流流域——并检验了不同的支系分化模型，同时重建其生物地理历史。基于多基因数据集构建的该属物种水平系统发育树（完整性约60%）具备良好稳健性，其结果显示，自中新生代至现代，支系积累速率始终保持近乎恒定：无论是否存在未采样物种，也不受这一时期频发的环境变化影响。这一模式与大型演化支的物种水平分化研究结果截然不同——后者通常呈现演化分支早期爆发式成种，随后速率随时间逐渐下降的特征。对不同生物地理演化支的识别表明，河流水文状况与分支成种之间存在关联，尽管有证据显示近期该研究类群曾多次向其分布范围南部扩散。本研究最终得出结论：具有热带大陆分布的多样淡水鱼类辐射类群，是检验分化假说、探究古地貌与古气候对现代生物多样性影响的重要研究对象。