Evolutionary comparisons between major environmental divides, such as between marine and freshwater systems, can reveal the fundamental processes governing diversification dynamics. Although processes may differ due to the different scales of their biogeographic barriers, freshwater and marine environments nevertheless offer similar opportunities for diversification in benthic, demersal, and pelagic habitats. Here, we compare the evolutionary patterns and processes shaping teleost diversity in each of these three habitats and between marine and freshwater systems. Using specimens from the National Museum of Natural History, we developed a data set of linear measurements capturing body shape in 2266 freshwater and 3344 marine teleost species. With a novel comparative approach, we contrast the primary axis of morphological diversification in each habitat with the major axis defined by phylogenetic signal. By comparing angles between these axes, we find that fish in corresponding habitats have more similar primary axes of morphological diversity than would be expected by chance, but that different historical processes underlie these parallel patterns in freshwater and marine environments. Marine diversification is more strongly aligned with phylogenetic signal and shows a trend toward lineages occupying separate regions of morphospace. In contrast, ecological signal appears to be a strong driver of diversification in freshwater lineages through repeated morphological evolution in densely packed regions of morphospace. In spite of these divergent histories, our findings reveal that habitat has driven convergent patterns of evolutionary diversification on a global scale. [Benthic–pelagic axis; body shape; convergent evolution; morphological diversification; phylogenetic signal.]

中文翻译：

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不同的过程推动海洋和淡水鱼类的平行进化

主要环境分界之间的进化比较，例如海洋和淡水系统之间的进化比较，可以揭示控制多样化动态的基本过程。尽管由于生物地理屏​​障的规模不同，过程可能会有所不同，但淡水和海洋环境仍然为底栖、底层和中上层生境的多样化提供了类似的机会。在这里，我们比较了这三个栖息地以及海洋和淡水系统之间形成硬骨鱼多样性的进化模式和过程。使用来自国家自然历史博物馆的标本，我们开发了一组线性测量数据，捕获了 2266 个淡水和 3344 个海洋硬骨鱼物种的体型。采用新颖的比较方法，我们将每个栖息地中形态多样化的主轴与系统发育信号定义的主轴进行对比。通过比较这些轴之间的角度，我们发现相应栖息地中的鱼类具有比偶然预期的更多相似的形态多样性主轴，但不同的历史过程是淡水和海洋环境中这些平行模式的基础。海洋多样化与系统发育信号更加一致，并显示出谱系占据形态空间不同区域的趋势。相比之下，通过形态空间密集区域的重复形态进化，生态信号似乎是淡水谱系多样化的强大驱动力。尽管有这些不同的历史，我们的研究结果表明，栖息地在全球范围内推动了进化多样化的趋同模式。[底栖-远洋轴；身材; 趋同进化；形态多样化；系统发育信号。]