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Since the Hawaiian Islands have never been connected to other land masses, the great variety of plants in Hawaii must be a result of the long-distance dispersal of seeds, a process that requires both a method of transport and an equivalence between the line ecology of the source area and that of the recipient area. There is some dispute about the method of transport involved. Some biologists argue that ocean and air currents are responsible for the transport of plant seeds to Hawaii. Yet the results of flotation experiments and the low temperatures of air currents cast doubt on these hypotheses. More probable is bird transport, either externally, by accidental attachment of the seeds to feathers, or internally, by the swallowing of fruit and subsequent excretion of the seeds. While it is likely that fewer varieties of plant seeds have reached Hawaii externally than internally, more varieties are known to be adapted to external than to internal transport. discussing different approaches biologists have taken to testing theories about the distribution of plants in Hawaii, discussing different theories about the transport of plant seeds to Hawaii, discussing the extent to which air currents are responsible for the dispersal of plant seeds to Hawaii, resolving a dispute about the adaptability of plant seeds to bird transport, resolving a dispute about the ability of birds to carry plant seeds long distances
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