Sahul's megafauna were vulnerable to plant‐community changes due to their position in the trophic network

Extinctions stemming from environmental change often trigger trophic cascades and coextinctions. Bottom–up occur when changes in the primary producers a network elicit flow-on effects to higher levels. However, it remains unclear what determines species' vulnerability bottom–up whether such were large contributor megafauna extinctions that swept across several continents Late Pleistocene. The pathways are particularly for Sahul (landmass comprising Australia New Guinea), where happened earlier than on other continents. We investigated potential role of Pleistocene by first developing synthetic networks varied topology identify how position (trophic level, diet breadth, basal connections) influences cascades. then constructed pre-extinction (~80 ka) models ecological community Naracoorte, south-eastern Sahul, assess observed could be explained Synthetic showed node decreased with increasing breadth connections. Extinct species Naracoorte more vulnerable overall these survived. extinct – tending low level therefore having relatively narrow breadths fewer connections plants made them vulnerable. also tended have few or no predators, network-position attribute suggests they might been new predators. Together, results suggest naivety predators contributed extinction event Sahul.