Data from: Evolutionary origin and early biogeography of otophysan fishes (Ostariophysi: Teleostei)

Biogeography of the mega-diverse, freshwater and globally-distributed Otophysi has received considerable attention. The attraction largely stems from assumptions as its ancient origin, and by being almost exclusively freshwater, their suitability as to explanations of trans-oceanic distributions. Despite multiple hypotheses explaining present-day distributions, problems remain, precluding more parsimonious explanations. Underlying previous hypotheses involve alternative phylogenies for Otophysi, uncertainties as to temporal diversification and assumptions integral to various explanations. We reexamine the origin and early diversification of this clade based on a comprehensive time-calibrated, molecular-based phylogenetic analysis and event-based approaches for ancestral range inference of lineages. Our results do not corroborate current phylogenetic classifications of otophysans. We demonstrate Siluriformes are never sister to Gymnotiformes and Characiformes are most likely non-monophyletic. Divergence-time estimates specify a split between Cypriniformes and Characiphysi as a result of fragmentation of Pangea. The early diversification of characiphysans either predated, or was contemporary with, the separation of Africa and South America, and involved a combination of within- and between-continental divergence events for these lineages. The inter-continental diversification of siluroids and characoids postdated major inter-continental tectonic fragmentations (<90Mya). Post-tectonic drift dispersals are hypothesized to account for current patterns of distribution of these latter two clades.

物种丰富、淡水栖息且全球广布的骨鳔总目（Otophysi）的生物地理学研究已受到广泛关注。这种关注主要源于其古老的起源特征，以及几乎完全局限于淡水生境的特性，使其成为解释跨洋分布格局的理想类群。尽管已有多项假说试图解释其现今的分布现状，但相关研究仍存在诸多问题，难以得到更具简约性的演化解释。此前的各类假说均存在争议点：包括骨鳔总目系统发育关系的不同解读、物种分化时间的不确定性，以及各类解释所依赖的核心假设。本研究基于全面的时间校准分子系统发育分析，以及用于推断类群祖先分布范围的基于事件的方法，重新审视了该演化支的起源与早期分化过程。研究结果并不支持当前的骨鳔类系统发育分类框架：我们证实鲶形目（Siluriformes）从未与电鳗目（Gymnotiformes）构成姊妹群，且脂鲤目（Characiformes）大概率并非单系群。分化时间估算结果显示，鲤形目（Cypriniformes）与脂鲤亚总目（Characiphysi）的分化事件源于泛大陆（Pangea）的裂解。脂鲤亚总目的早期分化要么早于非洲与南美洲的分离，要么与其同步，其分化过程同时涉及大陆内部与跨大陆的演化事件。鲶形类与脂鲤类的跨大陆分化则发生在主要的跨大陆构造裂解事件之后（晚于9000万年前）。我们推测，构造运动后的漂移扩散可解释这两个演化支现今的分布格局。