Collaborative Research: CMG: Mathematical Modeling and Bayesian Analysis of Paleocommunity Collapse during Mass Extinctions

pi建议研究在大规模灭绝期间初级生产的停止在传播灭绝和生态系统崩溃中的作用。在地球过去的极端生态危机期间，初级生产的破坏被认为是灭绝的近端机制，可能导致整个营养系统的二次灭绝雪崩。生态网络的复杂性对理解次生灭绝传播的途径提出了独特的挑战。本项目将采用数值模拟和贝叶斯统计建模相结合的方法来划分由于对物种的直接影响而导致的灭绝，以及由于营养资源损失而导致的灭绝。考虑到食物网的结构随着有机组成的变化而变化，pi将使用数值模拟来评估食物网对初级生产扰动的敏感性。他们预测，在大灭绝和灭绝后恢复的间隔期间，敏感性将下降。他们将使用贝叶斯统计模型，根据从二叠纪和新近纪晚期的特定古生物地理群落的化石记录中观察到的灭绝数据，估计初级和次级灭绝成分。他们将估计可能导致已观察到的灭绝程度的初级生产中断的最大程度。他们预测，如果光合作用的破坏和二次灭绝确实是生态系统崩溃的重要驱动因素，那么在大灭绝期间，这种水平会急剧上升。

The PIs propose to study the role of the shutdown of primary production, during times of mass extinction, in propagating extinction and ecosystem collapse. The disruption of primary production has been suggested as a proximal mechanism of extinction during extreme ecological crises in the Earth's past, perhaps causing avalanches of secondary extinction throughout trophic systems. The complexity of ecological networks presents a distinct challenge to understanding the pathways by which such secondary extinctions are propagated. This project will use a combined approach of numerical simulation and Bayesian statistical modeling to partition extinction due to direct effects on species, versus extinction caused by the loss of trophic resources. Given that food web structure varies with organismal composition through the periods of interest, the PIs will use numerical simulations to evaluate the sensitivity of food webs to perturbations of primary production. They predict that sensitivity will decline during intervals of mass extinction and post-extinction recovery. They will use Bayesian statistical modeling to estimate primary and secondary extinction components using observed extinction data from the fossil record of specific paleobiogeographic communities from the Permian and late Neogene. They will estimate the maximum levels of primary production disruption that could yield observed levels of extinction. They predict such levels to increase dramatically during intervals of mass extinction, if disruption of photosynthesis and secondary extinction were indeed important drivers of ecosystem collapse.