Life History Strategies For Four Common Species Of Ranunculaceae In Eastern Alpine Meadow On Qinghai Tibetan

It is expected an important effect of altitude on plant size, reproductive strategies and reproductive success within populations. The question of which resource allocation patterns will be selected to ensure male and female reproductive success has attracted many researchers, especially in reference to plants of alpine environments. Through field sampling and controlling experiment to examined variations of reproductive traits,resource allocation,sex allocation within raceme,sex-allocation trade-offs and the efforts of flower traits on pollinators of several common species of Ranunculaceae at the eastern Qinhai Tibetan Plateau, we studied the reproductive strategies,reproductive pattern and the potential mechanism of these species. The results showed:(1) Larger plant height rather than flower size at higher altitude for three species (A. trullifolia, D. pachycentrum and A. obtusiloba); larger mean seed size, but decreased aborted seeds per plant, seed set and seed number per plant at high altitude population in A. trullifolia; significant decrease of all traits and resource allocation in A. obtusiloba with altitude increasing.(2)The plant size in A.trullifolia was positively correlated with single flower mass,androecium mass and aborted seeds per plant, with significantly differed slopes between altitudes; In D. pachycentrum, the plant size was significantly positively correlated with androecium mass, regardless of effects of altitude and plant size; In A.obtusiloba, the plant size was significantly positively correlated with all reproductive characters, and the regression slope between plant size and seed mass per fruit differed between altitudes.(3) There was a marked decline in carpel number, female mass, seed number, and seed mass per fruit with flowering sequence within inflorescences of Aconitum gymnandrum, while anther number, male/female mass ratio and pollen/ovule ratio increased. Floral sex allocation was male-biased in top flowers, while seed set was constant among positions. Variation in the amount of pollen received cannot explain the observed results, and the flower-removal experiment did not improve the seed set of the remaining flowers, indicating that an unavoidable architectural effect has led to the position-dependent pattern of sex allocation with raceme. (4) There are variations among families for geimination and seeding traits in A. gymnandrum, showed significant genetic variation. Female and male function had significant genetic variations, and there were significantly positive genetic correlations between floral traits. With changes of flower position (from bottom to top) the genetic correlations weakens between traits, obviously influenced by position effect, the results are same with their parents. The stamen removal experiments did not improve the seed production, it suggested there no sex trade-off in A. gymnandrum.(5) After manipulating the flower of A. gymnandrum by removing the lateral sepals,sub-sepals,stamen and lateral sepals respectively, we compared with the control experiment and find there is no significant difference between seed production, suggests that the opening of two sub-sepals and lateral sepals have no effect on bumblebee effective behavior.