Table 2.

Relative abundance of parental species in the contact zone and the direction of hybridization in 6 cases from 4 genera

Hybrid (Location)	Relative abundance of parental species	Direction of hybridization
Sonneratia × gulngai (Qionghai, Hainan) (Wenchang, Hainan)	S. alba: S. caseolaris ~1:1 (71:97; 664:573) ~1:1 (83:112; 556:477)	(equally common)
S. × hainanensis (Wenchang, Hainan)	S. alba: S. ovata ~10:1 (340:37)	C♀ × R♂
Bruguiera × rhynchopetala (Haikou, Hainan)	B. sexangula: B. gymnorrhiza ~2:1 (98:53)	C♀ × R♂ (29) R♀ × C♂ (5)
Ligularia paradoxa × duciformis (Maoniushan, Yunnan)	L. paradoxa: L. duciformis ~5:1	C♀ × R♂
Rhizophora × annamalayana (West coast, Sri Lanka)	R. mucronata: R. apiculata ~100:1	C♀ × R♂
R. × lamarkii (Daintree River and Shoalwater Bay, Australia)	R. stylosa: R. apiculata ~100:1	C♀ × R♂

Note: For Sonneratia × gulngai, the hybrid zones both in Qionghai and in Wenchang are about 1 km long. We recorded the number of individuals of the parental species both within the zone of hybridization (the former) and in the neighboring 3 km-long zone (the latter). The latter zone is composed solely of parental species. For S. × hainanensis, we counted the number of individuals of S. alba only around the range of S. ovata and S. × hainanensis. Other cases are restricted the exact zones of hybridization.