| Androdioecy (male and hermaphroditic individuals coexist in the same population) is the rarest breeding system in Angiosperms. The morphological androdioecy has two essences after investigated:Functional dioecy and functional androdioecy. Studies of androdioecy were the function of male and hermaphroditic individuals in breeding system, the maintenance, origin and evolution of androdioecy. Tapiscia sinensis is an androdioecious species distributing in the south of the Yangtze River and South-western provinces in China. Hermaphrodites were fertilized from late May to early June. Zygote took about 10 months to dormancy and survived until next March. The fruits matured in next September. So flowers and fruits coexist on the same hermaphroditic plant during the flowering time. Tapiscia sinensis was already studied on taxology, ecology, anatomy and morphology, geobotany, introduction and domestication, reproductive biology and winter strategy of fruits. But pollination biology of Tapiscia sinensis has been not studied until now. Theoretical models of androdioecy based on Evolutionarily Stable Strategy (ESS) assumption require that male plants have at least twice of the fitness incurred by hermaphrodites through male function. Most studies about the maintenance of androdioecy focused on the relative male fitness. Some researchers discussed it via comparing the resource allocation of males and hermaphrodites. Such as theoretical analysis model of sex allocation has tended to assume that resource is available for allocation to sexual reproduction are divided optimally between male and female functions. Flowers and fruits coexist on the same hermaphroditic tree during blossom in Tapiscia sinensis, the hermaphroditic individual bear two life-styles. Resource competition may exist between flowers and fruits. Therefore, the aim of this study was designed (1) The pollination biology of androdioecious species Tapiscia sinensis was studied via morphology and structure of flower, flowering dynamics, pollinators, pollen viability, the acceptance of stigma from hermaphroditic flower and breeding system. (2) Determine the sex allocation of hermaphrodites through comparing the relative male fitness between male and hermaphroditic individuals; (3) Explore maintenance of androdiocious plant Tapiscia sinensis via surveying the relationship between flowers development and fruits growth on the same hermaphroditic plant.The results indicated:(1) Tapisicia sinensis is a typical androdioecious species with male and hermaphroditic plants. Hermaphroditic flowers have functional pollen. The flowering phonologies of male and hermaphroditic plants were identical. Duration of flowering was from late May to early June. The anthesis of a single flower could prolong 4 to 5 days. The stamens appeared heterotypical maturation and prolonged the pollen dispersion period of a single flower. Hermaphrodites were protogyny and the stigma had acceptance during the whole anthesis. Insects, such as bees, hover fly were the main pollinators, and higher visiting time was between 8:30 and 10:30.(2) Comparing with males, hermaphrodites had low male fitness. Males had high fitness in pollen viability, flower production and pollen germination. It suggested that resource allocation was partial to female function during the flower development occurred on hermaphroditic plant.(3) Flowers development and fruits growth were simultaneous. Pollination experiments shown that there were no differences in fruit set between self-and cross-pollinated. The reason may be resource limited caused by flowers and fruits developing at the same term in the hermaphroditic plant.On the basis of the above, Tapiscia sinensis was functional androdioecy. Existence of males may be a balance for a trade-off between resource allocation to flower development and fruit growth at the same term on the hermaphroditic plant, producing excellent pollen for population; the stamens of hermaphrodites may be a reproductive assurance and reward for pollinator.
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