A key question in paleoecology and macroevolution is whether assemblages of species (paleocommunities) are persistent entities that endure over millions of years. While community turnover in the face of abiotic change is the presumed norm, paleocommunities have been shown to persist for long time periods and regardless of environmental disruption. It remains an open question, however, as to what processes allow for this. We investigate these questions by analyzing the Carboniferous brachiopod paleocommunities from the Midcontinent of North America. These diverse communities were subjected to repeated and geologically rapid changes in sea level. Using a suite of statistical techniques, we characterize the nature and scope of changes in these paleocommunities over time. We find that, at the paleocommunity scale, there is no evidence for obdurate ecological stasis, with fluctuations in both taxonomic composition and the associated abundance of taxa. However, at a higher ecological scale, stability is manifest, as diversity patterns remain stable across time, with a consistent number of species that can exist in any given paleocommunity. This suggests ecological rules such as taxon packing are in effect, resulting in a form of ecological stability even in the face of constant disequilibrium, and parallels ecological patterns of disruption and recovery previously observed for invertebrate communities from modern marine systems. Based on these results, we advocate for consideration of different hierarchical entities and scales when interpreting the ecological dynamics of fossil assemblages, as focusing exclusively on changes in taxon identity/abundance or diversity levels can lead to very different results.

中文翻译：

---

名字无关紧要，但数字很重要：寻找北美中大陆石炭纪腕足类古群落的稳定性

古生态学和宏观进化的一个关键问题是物种组合（古社区）是否是持续存在数百万年的持久实体。虽然面对非生物变化的社区更替是假定的常态，但古社区已被证明可以持续很长时间，无论环境破坏如何。然而，什么过程允许这样做仍然是一个悬而未决的问题。我们通过分析来自北美中部大陆的石炭纪腕足类古群落来调查这些问题。这些多样化的社区受到海平面反复和地质快速变化的影响。使用一套统计技术，我们描述了这些古社区随时间变化的性质和范围。我们发现，在古社区范围内，没有证据表明存在顽固的生态停滞，分类组成和相关的分类群丰度都有波动。然而，在更高的生态尺度上，稳定性是显而易见的，因为多样性模式随着时间的推移保持稳定，在任何给定的古社区中都可以存在一致数量的物种。这表明生态规则（如分类群包装）是有效的，即使面对持续的不平衡，也会产生一种生态稳定性，并且与以前在现代海洋系统中观察到的无脊椎动物群落的破坏和恢复生态模式相似。基于这些结果，我们主张在解释化石组合的生态动力学时考虑不同的层次实体和尺度，