Extinction drives a discontinuous temporal pattern of species-area relationships in a microbial microcosm system

The species area relationship (SAR) can be a general law in ecology only if its formation mechanisms are clarified. Essentially, the SAR addresses the relationship between regional area and biodiversity, which is shaped by processes of speciation, extinction and dispersal. Since those three processes has temporal dynamics, we propose the hypothesis that the occurrence of SAR should also have temporal dynamics. Here, we designed independent closed microcosm systems, in which dispersal/speciation can be excluded/neglected, to reveal the role of extinction in shaping the temporal dynamics pattern of SAR. We find that extinction can shape SAR in this system independently. Due to the temporal dynamics of the extinction, SAR was temporally discontinuous. We also observe that small-scale extinctions modified community structure to promote ecosystem stability and shaped SAR, while mass extinction pushed the microcosm system into the next successional stage and dismissed SAR. Our result suggested that SAR could serve as an indicator of ecosystem stability; moreover, temporal discontinuity can be the explaination for many controversies in SAR studies.