The Research Of Flower Traits Evolution In Apline Plant Based On Community Phylogeny

The functional traits of plants reflect the adaptability to the local environments,and the biotic and abiotic factors have different effects on the evolution of plant functional traits and characteristics.As an important component of plant functional traits,reproductive traits are also selected by biological factors and abiotic factors.Flowers are important reproductive organs of seed plants,and are highly diversified under from biotic and abiotic pressures in the long evolutionary history.In alpine ecosystems with reduced pollinator service and harsh environment,the selective pressures on floral traits from the biotic and abiotic factor could be highly intensified,and thus analysis of the variance in floral traits is of great significance to understand the strategies and adaptation mechanisms for plant adaptation.In this thesis,evolution of floral traits in plants from alpine meadow in the Qinghai-Tibet Plateau was examined based phylogenetic analysis on community level,and the main results are in the following:1.Effects of floral morphology on flower temperature increment in alpine plants The low temperature of alpine environment would limit the development of reproductive organs and pollination process,and thus flower structures that increase the temperatures within flowers and inflorescence would protect anthers and ovules from the low temperature and then increase the reproductive success.In this study,we investigated the flower and leaf temperature of 64 alpine plants with an infrared camera equipped with a macro-lens,and then calculated the flower temperature increment(FTI)by subtracting the leaf temperature from the temperature of the reproductive organs.Based on these data,we examined the effects of phylogeny,flowers size,symmetry and color on the FTI.Our result showed that the phylogenetic signal of FTI among different species was weak,indicating that FTI among different species might result from the various demandsto temperature,independent of phylogenetic relationship.Furthermore,FTI increased with the increase of flower size,and FTI increased more quickly in zygomorphic flower than in actinomorphic flowers,but the effects of symmetry and color on the averaged FTI were minor across all species.Our results suggest that the differences in FTI are great among different species,but the contribution of FTI on plant reproductive success needs to be clarified in future researches.2.Phylogenetic analysis of UV floral traits The phylogenetic tree on community level was constructed by the maximum likelihood method using the sequences of mat K,ITS,trn L-F.In addition,in light of pictures photographed under UV light,the flower patterns were divided into four types: 1)flower pattern with a UV structure,2)flower pattern with a special structure,3)flower pattern with a contrasting background,4)flower pattern without traits.We used the D test in the R software platform and caper package to calculate the phylogenetic signals of the four traits.The results showed that the phylogenetic structure of the flower pattern with UV structure in the D test threshold model is the clumping of Brownian motion,but the intensity of the phylogenetic signal is not strong,which indicated that this trait was affected by phylogeny but with low intensity and might be associated with strong UV radiation in high altitude.There was a significant phylogenetic signal with strong intensity for flowers with special structure,which indicated that this pattern was related to the evolutionary history of plant species.The flower pattern with a contrasting background is significantly different from the two phylogenetic structures under the threshold model,and the intensity of the phylogenetic signal is also not strong,indicating that this pattern could be affected by the environmental factors.