Data from: Phylogenetic footprints of an Antarctic radiation: the Trematominae (Notothenioidei, Teleostei)

The teleost suborder Notothenioidei is restricted to the Southern Ocean and has been described as a species flock spanning the whole of it. Within the suborder, the subfamily Trematominae is important for coastal Antarctic ecosystems. The eleven Trematomus species occupy a large range of ecological niches. The genus is monophyletic if the genus Pagothenia (two additional species) and Cryothenia amphitreta, also nested within it, are included. Although the Trematominae have received much interest, the relationships among these fourteen species are still unclear. Several recent studies have tried to resolve these interrelationships; however no complete and clear picture has emerged, probably because of the use of a low number of insufficiently variable markers. The only common results places T. scotti as the sister-group of the rest of the subfamily and T. loennbergi close to T. lepidorhinus. We use here more variable markers. Four nuclear markers, two of which are new, and a mitochondrial marker for the biggest trematomine sampling ever gathered (14 species, 78 specimens). We found that several nuclear haplotypes are shared by several species (mostly in very closely related species). The haplotype patterns coupled with the cytogenetics of the subfamily suggest that a phenomenon of incomplete lineage sorting is likely to be at play. Using a calibration linked to fossil evidence, we evaluate the relative ages of each clade within the Trematominae to assess the proximity of the speciation events to one another. The main trematomine diversification was recent and sudden.

真骨鱼类的南极鱼亚目（Notothenioidei）仅局限分布于南大洋，被认为是覆盖整个南大洋的物种辐射集群。在该亚目内，南极鱼亚科（Trematominae）对于南极沿岸生态系统具有关键作用。该亚科下的11种南极鱼属（Trematomus）物种占据了广泛的生态位空间。若将鲍氏冰鱼属（Pagothenia，含2个物种）以及嵌套于南极鱼属内的双隐冰鱼（Cryothenia amphitreta）纳入分类范畴，则南极鱼属为单系群。尽管南极鱼亚科已受到学界广泛关注，但这14个物种之间的系统发育关系仍未明确。近期多项研究试图厘清这些类群间的亲缘关系，但始终未能得到完整清晰的系统发育框架，这可能是由于所使用的分子标记位点数量偏少且变异程度不足所致。目前仅得到一项共通的研究结论：斯科蒂南极鱼（Trematomus scotti）为该亚科其余物种的姊妹群，而伦贝格南极鱼（Trematomus loennbergi）与鳞吻南极鱼（Trematomus lepidorhinus）亲缘关系紧密。本研究采用了变异程度更高的分子标记：4个核基因标记（其中2个为首次开发的新标记）以及1个线粒体基因标记，同时采集了迄今为止规模最大的南极鱼亚科样本，涵盖14个物种共78个标本。研究发现多个核基因单倍型（haplotype）在多个物种间共享，且此类共享现象多出现于亲缘关系极近的物种中。结合该亚科的单倍型模式与细胞遗传学特征，提示不完全谱系分选（incomplete lineage sorting）现象极有可能在该类群的演化过程中发挥了作用。本研究借助与化石证据校准的分子钟，评估了南极鱼亚科各演化支的相对分化时间，以分析物种形成事件之间的紧密关联程度。南极鱼亚科的主要类群分化发生于近期且具有突发性。