The tropical niche conservatism hypothesis suggests that most groups should be most phylogenetically clustered in cold, dry environments. This idea has been well‐tested in plants and some animal groups, but not for fishes. We assess the geographic patterns of freshwater fish phylogenetic structure and investigate the relationships between these patterns and environmental variables across North America and within two biogeographic realms. Phylogenetic relatedness and diversity of 360 freshwater fish assemblages across North America were quantified with three metrics based on a well‐dated phylogeny, and were related to 15 environmental variables using correlation and regression analyses. Geographically, the data were analyzed for North America as well as for separate biogeographic realms. We found that cold temperatures are the strongest determinant of phylogenetic clustering overall. However, in the arid west, clustering is most pronounced in the driest regions. In eastern North America, phylogenetic clustering increases at higher latitudes, while the reverse is true in western North America. The strongest phylogenetic clustering for freshwater fish assemblages on the continent is found in the most arid, rather than the coldest, climate in North America. Our results highlight that patterns of phylogenetic structure of freshwater fishes in North America are driven by both ecological and evolutionary processes that differ regionally.

中文翻译：

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北美淡水鱼种群系统发育相关性和多样性的地理格局和环境相关性

热带利基保守主义假说表明，大多数群体应在寒冷干燥的环境中以系统发育最集中。这个想法已经在植物和一些动物群体中得到了很好的检验，但是对于鱼类却没有。我们评估了淡水鱼类系统发育结构的地理模式，并研究了北美和两个生物地理领域内这些模式与环境变量之间的关系。系统发育相关性和回归分析基于良好的系统发育史，通过三个指标对北美360种淡水鱼类种群的系统发育相关性和多样性进行了定量，并通过相关性和回归分析将其与15个环境变量相关联。在地理上，对北美以及单独的生物地理领域的数据进行了分析。我们发现，低温是总体系统发育聚类的最强决定因素。但是，在干旱的西部，最干旱的地区聚类最为明显。在北美东部，系统发育聚类在高纬度地区增加，而在北美西部则相反。在北美洲，最干旱而不是最冷的气候是该大陆上最强的淡水鱼类种群的系统发生聚类。我们的结果表明，北美淡水鱼类的系统发育结构模式是由区域差异的生态和进化过程驱动的。而在北美西部则相反。在北美洲，最干旱而不是最冷的气候是该大陆上最强的淡水鱼类种群的系统发生聚类。我们的结果表明，北美淡水鱼的系统发育结构模式是由区域差异的生态和进化过程驱动的。而在北美西部则相反。在北美洲，最干旱而不是最冷的气候是该大陆上最强的淡水鱼类种群的系统发生聚类。我们的结果表明，北美淡水鱼类的系统发育结构模式是由区域差异的生态和进化过程驱动的。