Phylogeny And Spatio-temporal Evolution Of The Maddenia Group Of Prunus(Rosaceae)

Mountain activity and the accompanying climate change are key triggers of redistribution and biodiversification,and studying geology and climate changes may help reconstructing the evolutionary history of certain taxa.As the Qinghai-Tibetan Plateau(QTP)with its adjacent area is an acknowledged hotspot of plant specification,the relationship between biodiversification and QTP uplifting is widely studied these years.However,with the huge amount of species,current studies can hardly elucidate how the diversity was formed.And former phylogenetic studies often use DNA fragments which contain less genetic information,thus the interspecific relationships and evolutionary histories can not be reconstructed correctly.With the development of next-generation sequencing(NGS)technologies,phylogenomical studies are useful in understanding the diversity and the evolutionary history of a taxon.The Maddenia group,a taxa of Prunus,is endemic to East Asia.Its distribution area is disjunct,from QTP to Wuyi Mountain in the east.It is ideal to study the spatio-temporal diversification history of the Maddenia group because of its small number of species,wide span of distribution area and various distribution pattern.And the chaos of morphology also makes phylogenomics a necessary method to tackle the problems in this group.In this study,32 Maddenia individuals were sampled,including all the species of all distribution areas.There plastid genomes were used to build Bayesian inference(BI)trees and most-likelihood(ML)trees.Molecular dating and ancestor area reconstruction were conducted to reveal the spatio-temporal diversification history.Morphological and micromorphological traits were also observed to provide evidence of the evolution history.The phylogenomics analysis illustrated that the Maddenia group is a monophyly with three geographically defined subclades: subclade I containing P.fujianensis,subclade II containing P.gongshanensis and P.himalayana,and subclade III containing P.hypoleuca,P.hypoxantha,P.incisoserrata and P.wilsonii.The Maddenia group was derived at about 33.28 Mya from the central China.The subclade I was derived at about 27.21 Mya in the southeast China,and fruit propagation played significant role in the formation of this subclade.Afterwards the subclade II and the subclade III diversified around 24.32 Mya.The ancestor of subclade II colonized QTP from southeast.Though the plastid genomes have not differentiated evidently in subclade III,morphological diversification has appeared.Though P.fujianensis is morphologically similar to P.hypoleuca and P.incisoserrata,the phylogenetic result proved it as a cryptic species.The hair distribution on the abaxial side of leaves and the glandular teeth are the most notable morphological differences in Maddenia.This study systematically elucidates the phylogeny of the Maddenia group,rebuilds the evolutionary history,and discusses the relationship between species diversification and the activity of mountains.The spatio-temporal evolution of the Maddenia group is undoubtedly another evidence that mountain activities influence the diversification of plants.