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[See preceding abstract] Controlled pollination experiments were made in 1975-76 on 11 species growing in Peninsular Malaysia and one (Shorea splendida) in Sarawak. Results show 3 kinds of breeding systems: outbreeding in Shorea sections Muticae, Pachycarpae and Richetioides, with free hybridization within section Pachycarpae (between S. splendida and S. stenoptera); inbreeding in Dipterocarpus oblongifolius; and apomixis in S. ovalis and probably in Hopea glabra. The predominance of outbreeding systems suggests that these have a strong selective advantage under rain forest conditions, despite physical difficulties with high species diversity.