Although available paleobiological data indicate that the geographic ranges of marine species are maintained throughout their entire observable durations, other evidence suggests, by contrast, that the ranges of higher taxa expand as they age, perhaps in association with increased species richness. Here, I utilize a database of Ordovician genus occurrences collected from the literature for several paleocontinents to demonstrate that a significant aging of the global biota during the Ordovician Radiation was accompanied by a geographic and environmental expansion of genus ranges. The proportion of genera occurring in two or more paleocontinents in the database, and two or more environmental zones within a six-zone onshore-offshore framework, increased significantly in the Caradocian and Ashgillian. Moreover, widespread genera tended to be significantly older than their endemic counterparts, suggesting a direct link between their ages and their environmental and geographic extents. Expansion in association with aging was corroborated further by demonstrating this pattern directly among genera that ranged from the Tremadocian through the Ashgillian. Taken together, these results are significant not only for what they reveal about the kinetics of a major, global-scale diversification, but also for what they suggest about the interpretation of relationships between diversity trends at the α (within-community) and β (between-community) levels.

中文翻译：

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年龄和区域的新视角：奥陶纪辐射期间属的地理和环境扩张

尽管可用的古生物学数据表明，海洋物种的地理范围在其整个可观察期间都保持不变，但其他证据表明，相比之下，更高分类群的范围随着年龄的增长而扩大，这可能与物种丰富度的增加有关。在这里，我利用从文献中收集的几个古大陆的奥陶纪属出现数据库来证明在奥陶纪辐射期间全球生物群的显着老化伴随着属范围的地理和环境扩展。数据库中两个或多个古大陆中出现的属比例，以及六区陆上-近海框架内的两个或多个环境区，在卡拉多西亚和阿什吉利亚显着增加。而且，广泛分布的属往往比它们的地方性同类更古老，这表明它们的年龄与其环境和地理范围之间存在直接联系。通过直接在从 Tremadocian 到 Ashgillian 的属中证明这种模式，进一步证实了与衰老相关的扩张。总而言之，这些结果不仅对于它们揭示的重大全球规模多样化的动力学意义重大，而且对于它们对解释 α（社区内）和 β 的多样性趋势之间关系的建议也很重要。社区之间）水平。通过直接在从 Tremadocian 到 Ashgillian 的属中证明这种模式，进一步证实了与衰老相关的扩张。总而言之，这些结果不仅对于它们揭示的重大全球规模多样化的动力学意义重大，而且对于它们对解释 α（社区内）和 β 的多样性趋势之间关系的建议也很重要。社区之间）水平。通过直接在从 Tremadocian 到 Ashgillian 的属中证明这种模式，进一步证实了与衰老相关的扩张。总而言之，这些结果不仅对于它们揭示的重大全球规模多样化的动力学意义重大，而且对于它们对解释 α（社区内）和 β 的多样性趋势之间关系的建议也很重要。社区之间）水平。