Reproductive Strategies Of Common Species Of Ranunculaceae At Alpine Meadow In Qinghai Tibetan Plateau

Reproductive strategies, especially resource allocation are central of study of plant life history. Studies on resource allocation were focused on reproduction allocation and sex allocation. The former is core of life history evolution; the latter is about optimal allocation of reproductive resources between sexes, attempted to interpret the diversity of plant breeding systems. There are a lot of unique plants in Alpine Meadow at Eastern QinghaiTibetan Plateau. How to adapt the especial environment of Alpine, and what reproductive strategies appear for these species, which provide a special chance for ecologists and evolutionists. Therefore, we selected common species of Ranunculaceae. comparative primordial plants in Alpine Meadow at Eastern QinghaiTibetan Plateau, and studied the reproductive strategies, such as reproductive allocation, especially sex allocation, to understand how the plants adapt the environmental conditions. The results showed:(1) At higher altitude, the self-incompatible plant, such as Trollius ranunculoides tended to become limited by pollination rather than by nutrient availability, while the self-compatible plants, such as Anemone rivularis and A. obtusiloba seemed not to be limited by pollen availability, which suggested that ability of self pollination for alpine plants may be a mechanism of reproductive assurance.(2) Influences induced by high altitude on the reproduction of these species occurred on different reproductive characters, which suggest species-specific adaptive strategies. The influences are dependent on plant size to some extent. It means that plants adjust the relationships between plant size and reproductive traits to adapt the varied environment.(3) The reproductive allocation at flowering and at fruiting did not always decrease with altitude as predicted (only RA at fruiting A. obtusiloba decreased 30% with altitude increasing), different from Iwasa and Cohen's prediction. This may result from higher nutrients availability in soil at higher sites. Although self-pollination may be an assurance mechanism alleviating pollinated limitation, changes of allocation pattern, i.e. male-biased floral sex allocation in A. rivularis and higher allocation to attractive structure in A. obtusiloba seem to act upon improving pollinator visits at high altitude, not in self-incompatible T. ranunculoides.(4) Significant variation of flower size between different habitats in Trollius ranunculoides was found.