Data from: Niche conservatism over deep timescales and diverse niche axes in land vertebrates

Aim: There has been considerable interest in niche conservatism, the idea that ecological variables are similar among related species. Much research has focused on climatic niches of recently diverged species, rather than deeper timescales or non-climatic niche axes. Furthermore, it has been suggested that conservatism disappears over deeper timescales, and is greater in alpha niche traits (like diet and microhabitat) than beta niche variables (like climate). Here, we test these two ideas by comparing patterns of phylogenetic conservatism among 10 niche variables across major clades of land vertebrates. Location: Global. Time period: Present to 350 million years ago. Major taxa studied: Tetrapods, including amphibians, mammals, lepidosaurs (including lizards and snakes), turtles, crocodilians, and birds. Methods: The 10 niche variables included four alpha niche components (diet, diel activity, habitat, body temperature) and six beta niche components (related to climatic temperature and precipitation). We analyzed these variables on time-calibrated phylogenies with similar taxon sampling (~1700 species), using phylogenetic signal (lambda) to estimate conservatism, along with the D-statistic and estimates of evolutionary rates. Results: Phylogenetic signal was generally strong across all variables, with lambda generally >0.80 (with 1.0 representing maximum signal). Nevertheless, mean phylogenetic signal was lower in beta niche traits than alpha niche traits (based on lambda and especially the D-statistic), and alpha niche traits showed significantly slower rates of evolution. Main conclusions: We address two long-held views in the literature on niche conservatism, rejecting one but supporting the other. We show that phylogenetic signal does not disappear over deep timescales for many important niche variables, even over 350 million years. We also generally support greater conservatism in alpha niche traits than beta niche traits over hundreds over millions of years, a pattern that was previously suggested (but not explicitly tested) based on closely related species.研究主旨：生态位保守性（niche conservatism）指近缘物种间生态变量保持相似的现象，目前学界对此关注度颇高。现有大量研究聚焦于近期分化物种的气候生态位，而非更深地质时间尺度或非气候生态位维度。此外，有观点提出，生态位保守性会随更深时间尺度逐渐消失，且阿尔法（alpha）生态位性状（如食性、微生境）的保守性要高于贝塔（beta）生态位变量（如气候）。本研究通过比较陆生脊椎动物主要支系下10个生态位变量的系统发育保守性模式，对上述两个观点进行验证。 研究范围：全球。 时间跨度：现今至3.5亿年前。 研究类群：四足动物（Tetrapods），包括两栖类、哺乳类、鳞龙类（lepidosaurs，含蜥蜴与蛇类）、龟类、鳄类及鸟类。 研究方法：本研究选取的10个生态位变量包含4项阿尔法生态位组分（食性、昼夜活动模式、生境、体温）与6项贝塔生态位组分（与气候温度、降水相关）。我们以相似的类群采样量（约1700个物种）对时间校准后的系统发育树进行分析，采用系统发育信号（phylogenetic signal，lambda）评估保守性，同时结合D统计量与进化速率估计值开展分析。 研究结果：所有变量的系统发育信号普遍较强，lambda值大多大于0.80（1.0代表最大信号）。不过，基于lambda值尤其是D统计量的结果显示，贝塔生态位性状的平均系统发育信号低于阿尔法生态位性状，且阿尔法生态位性状的进化速率显著更慢。 主要结论：本研究针对生态位保守性领域的两个长期主流观点开展验证，最终否定其一、支持另一。我们发现，即便在3.5亿年的漫长地质时间尺度下，许多重要生态位变量的系统发育信号也并未消失。同时，本研究总体支持“阿尔法生态位性状的保守性在数百万至数亿年的时间尺度上高于贝塔生态位性状”这一此前仅基于近缘物种提出、但未得到明确验证的规律。