Biogeography and origin of Lilium longiflorum and L. formosanum II -- intra- and interspecific variation in stem leaf morphology, flowering rate and individual net production during the first year seedling growth.

摘要

L. longiflorum and L. formosanum are closely related species endemic to the subtropical islands of the Ryukyu Archipelago and Taiwan. Stem leaf morphology, flowering rate within population and individual net production during the first year seedlinggrowth were determined to clarify whether they can differentiate these two species, and reflect adaptive strategy during species and local population establishment. Four experimental populations of L. longiflorum and five of L. formosanum from differentlocalities in Taiwan, and in Ryuku archipelago and Kyushu, Japan, covering almost their native distribution, were grown under greenhouse condition in the University Farm in northern Kyushu, Japan. L. longiflorum showed distinct lower leaf length:width ratio than L. formosanum. Flowering rate and net production tended to decrease along the population location, northward across the archipelago arc and toward higher altitude within the mainland of Taiwan, showing obvious geographic cline (geographically continuous variation). Low degrees of flowering rate and net production in northern L. longiflorum were associated with high frequency of individuals that obtained little net production from spring to summer, indicating an acquired dormancy status. L. formosanum native to about 3000 m altitude showed higher resource allocation to the mother bulb. These variations in the growth habits within the species reflect region-specific adaptive strategy of L. longiflorum and L. formosanum for climate during the glacial period and that in highlands of the mainland of Taiwan, respectively. Higher annual net production and an earlier shift to the reproductive phase of L. formosanum is highly more advantageous in population establishment under disturbed and competitive environment, where L. longiflorum is rarely found.