The Phylogeny And Evolution Of Oreocharis In Hainan Island

Gesneriaceae of Asia is a middle-sized family,including about 67 genera and over 2300 species,the diversification center is located in South China.The taxonomy and systematics of Gesneriaceae has been revised many times,especially,the Oreocharis has become the second largest taxa of Gesneriaceae in China,～ 150 species.The Oreocharis showed manifold divergences in floral traits,however,the geographic distribution pattern,phylogeny and evolution of Oreocharis are still unclear.There were four recognized taxa of Oreocharis in Hainan Island,all are endemic to the island,which presented the distinct speciation history and evolution pattern,which offers an excellent opportunity to understand the evolution of Gesneriaceae and the speciation and maintenance mechanism of endemics diversification in the island.This paper aimed to study the biogeography pattern of Oreocharis firstly,then,the phylogeny of Oreocharis in Hainan Island with adjacent regions was reconstructed based on modern simplified genome sequencing technology RAD-seq,revealed the molecular biogeographic pattern of Oreocharis in Hainan Island,and analyzed the evolutionary history and adaptation mechanism of floral traits of Oreocharis.Finally,the potential geographical distribution pattern and dominant climatic factors of Oreocharis in Hainan Island were studied based on Maximum Entropy(Max Ent)algorithm,and we reconstructed a Key to species of Oreocharis in Hainan Island based on morphological characteristics and molecular systematics.The results showed below:1 The biogeography pattern and historical systematic evolution of OreocharisThe Oreocharis has ～ 150 species totally,whose species diversification centers were recognized in the south and southeast China.We used nuclear ITS1/2 and chloroplast trn L-F sequences of 58 species in Oreocharis to construct a phylogenetic tree,and we found:(1)The Oreocharis can be separated into two clades,Clade A was mainly distributed in southwest China and dominated by yellow corolla,stamens 4;Clade B was mainly distributed in south and southeast China and dominated by purple corolla,some species evolved with 2 stamens.(2)The evolution from zygomorphy to actinomorphy in corolla was detected.The geographic isolation and soil heterogeneity caused by Karst and Danxia landforms,and divergent selection on different and diverse bee pollinators may offered opportunities to various floral traits evolution in Oreocharis.2 Phylogeny of Oreocharis in Hainan IslandIn this study,the 13 populations of Oreocharis in south central mountains of Hainan Island were sampled,we combined DNA(nuclear ITS1/2 sequences and cp DNA trn L-F and ycf1b)to evaluate phylogeny of Oreocharis from the island,together with morphological similarity analysis using 16 morphological traits.The results showed Hainan Oreocharis taxa were monophyletic with relative low genetic diversity within populations,highly significant genetic differentiation amongst populations and a significant phylogeographical structure.The 13 populations formed six genetically distinct groups,roughly correspondent to the currently recognized four species and two unknown lineage.The PCA analyses of morphological traits indicate six distinctive groups,differing mainly in petal colour and corolla shapes.These taxa are distributed in high altitude areas with obvious isolation,the roles of river and mountain isolation in the origin and distribution of these three lineages are discussed.3 Biogeography of Oreocharis in Hainan Island based on RAD-seqIn this study,we analyzed the genetic structure,genetic relationships,divergence time and ancestral distribution region of Oreocharis in Hainan Island based on RAD-seq.We found that there were gene introgression and hybridization happened among 10 populations and diverged from late Miocene.The possible six taxa had experienced four dispersal events,four geographic isolation events and zero extinction events.The evolution from zygomorphy to actinomorphy in corolla,from thin tubular flower to funnel and campanulate flower were happened.Distinctive habitat of limestone landforms,the isolation of Changhua River and distinctive environment of tropical montane cloud forest were main factors of Oreocharis in Hainan Island,and monsoon climate offered ample hydrothermal conditions for speciation.4 Potential distribution region and dominant climatic factorsBased on 13 occurrence sites and 19 environmental variables,the Maximum Entropy(Max Ent)algorithm was used to create a model linking the potential distribution ranges of Oreocharis in Hainan Island in Last Glacial Maximum(LGM),current period and 2070,reconstructed migration history of geographical distribution pattern of Oreocharis in Hainan Island since Last Glacial Maximum(LGM),and identified the main environmental factors and control mechanism of influence on geographical distribution.We found that four types of potential distribution ranges of Oreocharis in Hainan Island in these three period,high suitable habitats centered in middle and high altitudinal region in South-central mountain systems.The potential suitable habitats in different regions experienced varied degrees of constriction and expansion,the main environmental factors of influence on potential distribution ranges of Oreocharis in Hainan Island including seven factors,ie.altitude,max temperature of warmest mouth and isothermality.The gradually raised temperature of the atmosphere,greenhouse effect and habitat destruction had a negative effect on suitable habitat of Oreocharis in Hainan Island.5 Diversity and report of new species of Oreocharis in Hainan IslandDuring several fieldwork trips in the past five years,we found that there were some taxa of Oreocharis in Hainan Island differed from acknowledged taxa in floral morphological characters.After checked all type specimen currently recognized for Oreocharis,careful literature studies and combined molecular biology data,we were convinced that this three taxa represent three new species,they were published Oreocharis jasminina S.J.Ling,F.Wen & M.X.Ren,the flower is distinct and looks like Jasminum nudiflorum.The unpublished Oreocharis sp.1 is from karst habitat around Daguangba Dam and Oreocharis sp.2 from Mt.Jianfeng.And we reconstructed a Key to species of Oreocharis in Hainan Island,the speciation and floral evolution of Oreocharis in Hainan Island and the significance of new taxa on system evolution of Oreocharis were discussed.