|
There are a lot of unique plants in Alpine Meadow of Eastern Qinghai-Tibetan Plateauof China. How to adapt to the stressful environment of Alpine and what reproductivestrategies suit these species? Which provides a special chance for ecologists andevolutionists? Reproductive success is the important part of plants adapting to the naturalconditions. Under specific conditions, plants form the optimal reproductive strategy throughthe optimal life history characteristics. Therefore, we selected 112 populations of sevenspecies of Saussurea DC. in Alpine Meadow of Eastern Qinghai-Tibetan Plateau, and studiedthe adaptive strategies, especially the correlation between the altitude and reproductiveallocation, sex allocation and sex organ, to explain how they adapt to the stressfulenvironment, and finally become dominant species. The results are as follow:1. The reproductive investment in the flowering phase of Annual or biennial Saussureastella is higher than its nutrient investment, while six other perennial plants’nutrientinvestment is higher than their reproductive investment, regardless of their flowering phaseor fruiting period.2. There is trade-off between male and female function. S. nigrescens is inclined toinvestment in male function, and get male fitness through pollen pathway. Other six speciesinvest more in female function, and get female fitness through seed reproduction.3. With the changes of altitudinal gradient, the seven species of Saussurea reachsuccessful mating and improve success rate of reproduction through the variation of sexualorgans.4. With the increasing of altitude, the number and weight of S. parviflora, S.epilobioides, S. subulisquama, S. iodostegia and S. nigrescens decreases, but they ensuresuccessful reproduction by improving maturation rate of seeds and lengthening pappus.5. Qinghai Tibetan Plateau has higher altitude and air transparence, strong sunshine andultraviolet ray, vivid purple flowerlet can reflect different lightwave, avoiding the amassmentof too much heat and injury from strong light.6. Flourishing, getting enough sunshine can raise the inner temperature of inflorescencesand improve their growth; on the other hand, bracts wrap inflorescences to prevent the maleand female gametocyte from ultraviolet ray. Thus, flowers’male and female fitness andplants’adaptive ability is improved.7. Approach herkogamy is good for plants’female function, and can decrease thedisturbance between female and male function.
|