A global test of the subsidized island biogeography hypothesis

Aim The decreasing capacity of area to predict species richness on small islands (the small‐island effect; SIE) seems to be one of the few exceptions of the species–area relationship. While most studies have focused on how to detect the SIE, the underlying ecological factors determining this pattern remain largely unexplored. Here, we evaluate one of the few mechanisms proposed to explain the SIE, the subsidized island biogeography hypothesis, which posits that marine productivity around small islands may alter their expected species richness. Location Seven hundred and ninety islands worldwide, including 420 islands