Diversity Pattern And Underlying Determinants Of Orchids In Yunnan,China

Biodiversity is important part of the earth's biosphere and is the material basis for human survival.With the continuous understanding of biodiversity,the traditional method of floristic research based on family,genus and species has been unable to reveal the secret of biodiversity.With the advent of the era of big data,the construction of regional trees of life and the accumulation of geographical distribution data of species provide a good opportunity to solve this problem.This paper takes orchids in Yunnan as an example,reconstruct the phylogenetic relationships,collect its environmental data(energy,percipitation,habitat heterogeneity),analysis the patterns of the geographic composition,taxonomic diversity,phylogenetic diversity and phylogenetic structure,and the causes of their formation.The results are as follows:1.There are 952 and 162 genera in Yunnan,belonging to 5 subfamilies,of which2 genera and 4 species are Apostasioideae,2 genera and 47 species are Cypripedioideae,5 genera and 8 species are Vanilloideae,36 genera and 219 species are Orchidoideae,with 116 genera 674 species are Epidendroideae.There are 488 epiphytic types,436 terrestrials and 28 saprophytics.The floras are characterized by remarkable tropical attribute,complex geographical composition and extensive communication with other floras in the world.2.The taxonomic diversity and phylogenetic diversity of all orchids and terrestrials are centered in the south and northwest of Yunnan,which of it is decreased significantly in epiphytics from southwest to northeast of Yunnan.3.The phylogenetic structure of all Orchidaceae is more and more discrete from south to north,which of terrestrials gradually converged northward,while epiphytics showes increasing aggregation from the periphery to the center.4.The pattern of the phylogenetic diversity of all orchids and tropical components have the strongest correlation with and mean annual precipitation.Low winter temperature controlls the phylogenetic diversity of temperate components and terrestrials,and the phylogenetic diversity of epiphytics had the strongest correlation with moist index.5.In the early orchid flora evolution stage of Yunnan,the spatial heterogeneity of temperature shaped the phylogenetic structure of all orchids,and the mean annual temperature affected the phylogenetic structure of terrestrials and epiphytics.In recent evolutionary events,the moist index played a key role in influencing of the phylogenetic structure of all orchids,and mean relative humidity is important to terrestrials,while the moist index influenced terrestrials.6.From the perspective of evolutionary history and modern climate,the climate factors are the dominant factors for the diversity of all orchids and epiphytics.The evolutionary history of terrestrials is of great significance for its present pattern.