Simplification and Vulnerability of Large Mammal Food Webs During the Early–middle Pleistocene Transition

The Early–Middle Pleistocene Transition (EMPT) represents a fundamental transformation in global climate, marked by progressively greater climatic oscillations and a shift towards a quasi-100 ky frequency. Intensifying aridity and declining forest cover have led to extinction or migration among terrestrial mammals, having a significant impact on ecosystems. However, how the EMPT reshaped the structure and function of terrestrial food webs remains poorly understood. In this study, we reconstructed large-mammal food webs from 26 classical fossil assemblages spanning the early to middle Pleistocene across East Asia using a trait-based food web inference model. We quantified temporal changes in the biological composition and structural properties of these time-averaged food webs through network analysis. Alongside a decline in taxonomic diversity, the food webs exhibited a reduced complexity and stability after the early Pleistocene, although patterns of recovery in properties varied between regions. In the northern East Asia, fossils of large mammals were rare during peak environmental deterioration, and properties measuring the complexity and stability of food webs remained low when they reappeared. Communities in the southern East Asia also became simplified and vulnerable during environmental change, but recovered rapidly once conditions improved. These findings demonstrate that the EMPT has widespread and sometimes profound impacts on terrestrial food webs in East Asia.