The Importance of Size and Location Within Gregarious Populations of Ernietta plateauensis
The Importance of Size and Location Within Gregarious Populations of Ernietta plateauensis
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DOI：
10.3389/feart.2021.749150
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发表时间：
2021-10-18
影响因子：
2.9
通讯作者：
Laflamme, Marc
中科院分区：
文献类型：
--
作者：
Gibson, Brandt M.;Darroch, Simon A. F.;Laflamme, Marc
Ernietta plateauensis是一种半底栖的宏观真核生物，在纳米比亚的埃迪卡拉纪晚期（近似548-539 Ma）浅海环境中常见，亲缘关系未知。Ernietta的原位组合的发现表明，这些生物生活在聚集的种群中，而采用计算流体动力学（CFD）建模的研究支持了这样的假设，即这些生物可能表现为群居的悬浮饲料，类似于当今海洋环境中许多现存的无脊椎动物门。对这些原地种群中的个体进行仔细的普查和测量提供了一个机会，可以研究它们在更大的种群中的大小和位置如何影响营养物质的输送动态。在这项研究中，我们建立在以前的工作，通过模拟流体流动的Ernietta聚合体，包括不同大小的个人，并重建人口Ernietta保存在原位农场汉斯堡，纳米比亚。我们使用固定和随时间变化的计算流体动力学的组合来重建营养物质携带的流动路径，并比较营养物质在不同形状和大小的个体之间分配的效率。我们的研究结果表明，较小的Ernietta经验有限的再循环在他们的腔相比，较大的个人。此外，在空间上精确的分布，减少再循环仅限于孤立的个人的任何大小，而较小的个人发现下游较大的接收增强腔混合。这些重建的流动模式说明，与小尺寸相关的缺点显然是介导的位置内的整体聚集，这表明一个复杂的相互作用的控制喂养效率。这反过来又表明，成年埃尼埃塔的聚集很可能起到了“托儿所”的作用，为年轻个体的定居和成长创造了理想的局部条件。
Ernietta plateauensis is a semi-infaunal macroscopic eukaryote of unknown affinities common in latest Ediacaran (similar to 548-539 Ma) shallow marine settings in Namibia. The discovery of in-situ assemblages of Ernietta has demonstrated that these organisms lived in aggregated populations, while studies employing computational fluid dynamics (CFD) modeling have supported the hypothesis that these organisms were likely behaving as gregarious suspension feeders, analogous to many extant invertebrate phyla in present-day marine environments. Careful census and measurement of individuals within these in-situ populations offers an opportunity to examine how their size and location within a larger population affect nutrient delivery dynamics. In this study, we build on previous work by simulating fluid flow over aggregations of Ernietta comprising individuals of disparate sizes, and additionally reconstruct a population of Ernietta preserved in-situ from Farm Hansburg, Namibia. We use a combination of stationary and time-dependent CFD to reconstruct nutrient carrying flow paths, and compare the efficiency with which nutrients are partitioned between individuals of different shapes and sizes. Our results demonstrate that smaller Ernietta experience limited recirculation within their cavities compared to larger individuals. Furthermore, in spatially-accurate distributions, reduced recirculation is limited to isolated individuals of any size, while smaller individuals found downstream of larger ones receive enhanced cavity mixing. These reconstructed flow patterns illustrate that the disadvantage associated with small size is apparently mediated by location within the overall aggregation, suggesting a complex interplay of controls on feeding efficiency. This in turn suggests that aggregations of adult Ernietta would likely have performed a 'nursery' function, creating localized conditions ideal for the settlement and growth of younger individuals.