Factors influencing test porosity in planktonic foraminifera
Factors influencing test porosity in planktonic foraminifera
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DOI：
10.5194/bg-15-6607-2018
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发表时间：
2018-11-07
期刊：
影响因子：
4.9
通讯作者：
Hull, Pincelli M.
中科院分区：
文献类型：
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作者：
Burke, Janet E.;Renema, Willem;Hull, Pincelli M.
有孔虫测试壁孔隙附近的线粒体聚集表明这些穿孔在代谢气体交换中发挥着关键作用。因此，孔隙测量可以提供一种跟踪化石记录中代谢率变化的新方法。然而，在浮游有孔虫中，平均孔隙面积、密度和孔隙度（开放孔隙空间的测试壁的总百分比）的变化已被不同地归因于环境、生物和分类学驱动因素，使这种解释复杂化。在这里，我们研究了718个人的孔隙特征的环境，生物和进化的决定因素，代表17个形态种的浮游有孔虫从6个核心顶部在北大西洋。使用随机森林模型，我们发现，孔隙度主要与测试表面积，测试体积，和栖息地温度，在确定代谢率的关键因素。为了测试这种相关性是否是通过隐种与不同生物群落的关联而产生的，我们在三种不同的温度条件下培养了Globigerinoides ruber，发现孔隙度随着温度的升高而增加。至关重要的是，这些结果表明，孔隙度可以是塑性的：在个体有孔虫的生命周期内，响应环境驱动因素而变化。这表明孔隙度作为有孔虫代谢率的替代物的潜力，对于解释非模拟环境中的地球化学数据和有孔虫生理学具有重要意义。它还强调了表型可塑性的重要性（即，生态表型）在解释现代和化石记录中形态变异的某些方面。
The clustering of mitochondria near pores in the test walls of foraminifera suggests that these perforations play a critical role in metabolic gas exchange. As such, pore measurements could provide a novel means of tracking changes in metabolic rate in the fossil record. However, in planktonic foraminifera, variation in average pore area, density, and porosity (the total percentage of a test wall that is open pore space) have been variously attributed to environmental, biological, and taxonomic drivers, complicating such an interpretation. Here we examine the environmental, biological, and evolutionary determinants of pore characteristics in 718 individuals, representing 17 morphospecies of planktonic foraminifera from 6 core tops in the North Atlantic. Using random forest models, we find that porosity is primarily correlated to test surface area, test volume, and habitat temperature, key factors in determining metabolic rates. In order to test if this correlation arose spuriously through the association of cryptic species with distinct biomes, we cultured Globigerinoides ruber in three different temperature conditions, and found that porosity increased with temperature. Crucially, these results show that porosity can be plastic: changing in response to environmental drivers within the lifetime of an individual foraminifer. This demonstrates the potential of porosity as a proxy for foraminiferal metabolic rates, with significance for interpreting geochemical data and the physiology of foraminifera in non-analog environments. It also highlights the importance of phenotypic plasticity (i.e., ecophenotypy) in accounting for some aspects of morphological variation in the modern and fossil record.