The Biota of Long-Distance Dispersal. V. Plant Dispersal to Pacific Islands

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Abstract
The native Hawaiian flora is analyzed by genera for probable method of arrival of ancestral immigrants, and these data are listed in detail and discussed. Fruit and seed morphology are used as evidence for mode of dispersal interpreted in the light of known dispersal methods. Modes of arrival on the Hawaiian islands are computed as percentages, and similar percentages are presented for angiosperms of other Pacific oceanic islands and archipelagos. These data show that ecology of recipient island is much more important than distance in determining modes of successful transport. On high islands, internal transport by birds is of prime importance, and decreases only slightly with increased distance. On atolls, oceanic drift is of overwhelming importance. Adherence to feathers by barbed or bristly seeds or fruits is of maximum importance on dry volcanic islands. Transport of seeds by air flotation decreases sharply with distance, and thus is responsible for only a few genera on the Hawaiian Islands. To account for floras of oceanic islands, no factors not currently operative seem necessary. Shore birds are cited as a particularly likely vector for transport of fleshy-fruited plant species. Reasons are given for absence of South Pacific drift species in the North Pacific. The great similarity between floras and faunas of the Pacific oceanic islands and those of Mascarene oceanic islands derives from the fact that islands in both the Pacific and Indian oceans have been populated by those groups from Indo-Malaysia capable of long-distance dispersal. The implications of the present data for inter-continental and intracontinental dispersal are discussed, and the implications for hypotheses of continental drift are explored.