Polyploids contribute substantially to plant evolution and biodiversity;however,the mechanisms by which they succeed are still unclear.According to the polyploid adaptation hypothesis,successful poly-ploids spread by repeated adaptive responses to new environments.Here,we tested this hypothesis using two tetraploid yellowcresses(Rorippa),the endemic Rorippa elata and the widespread Rorippa palustris,in the temperate biodiversity hotspot of the Hengduan Mountains.Speciation modes were resolved by phylogenetic modeling using 12 low-copy nuclear loci.Phylogeographical patterns were then examined using haplotypes phased from four plastid and ITS markers,coupled with historical niche reconstruction by ecological niche modeling.We inferred the time of hybrid origins for both species as the mid-Pleistocene,with shared glacial refugia within the southern Hengduan Mountains.Phylogeo-graphic and ecological niche reconstruction indicated recurrent northward colonization by both species after speciation,possibly tracking denuded habitats created by glacial retreat during interglacial periods.Common garden experiment involving perennial R.elata conducted over two years revealed significant changes in fitness-related traits across source latitudes or altitudes,including latitudinal increases in survival rate and compactness of plant architecture,suggesting gradual adaptation during range expansion.These findings support the polyploid adaptation hypothesis and suggest that the spread of polyploids was aided by adaptive responses to environmental changes during the Pleistocene.Our results thus provide insight into the evolutionary success of polyploids in high-altitude environments.

Ting-Shen Han;Zheng-Yan Hu;Zhi-Qiang Du;Quan-Jing Zheng;Jia Liu;Thomas Mitchell-Olds;Yao-Wu Xing

CAS Key Laboratory of Tropical Forest Ecology,Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences,Mengla,Yunnan 666303,China;Center of Plant Ecology,Core Botanical Gardens,Chinese Academy of Sciences,Mengla,Yunnan 666303,China;Department of Biology,Duke University,Box 90338,Durham,NC 27708,USA;University of Chinese Academy of Sciences,Beijing 100049,Chin

植物多样性（英文）

[1]Ting-Shen Han;Zheng-Yan Hu;Zhi-Qiang Du;Quan-Jing Zheng;Jia Liu;Thomas Mitchell-Olds;Yao-Wu Xing-.Adaptive responses drive the success of polyploid yellowcresses(Rorippa,Brassicaceae)in the Hengduan Mountains,a temperate biodiversity hotspot)[J].植物多样性（英文）,2022(05):455-467

yellowcresses,Polyploids,ploids,Phylogeographical,Phylogeo,denuded,polyploids

Adaptive,responses,drive,Rorippa,Brassicaceae,Hengduan,Mountains,temperate,biodiversity,hotspot,contribute,substantially,plant,however,mechanisms,by,which,they,succeed,still,unclear,According,adaptation,hypothesis,successful,repeated,adaptive,new,environments,Here,tested,this,using,two,tetraploid,endemic,elata,widespread,palustris,Speciation,modes,were,resolved,phylogenetic,modeling,copy,nuclear,loci,patterns,then,examined,haplotypes,phased,from,four,plastid,ITS,markers,coupled,historical,niche,reconstruction,ecological,We,inferred,hybrid,origins,both,species,mid,Pleistocene,shared,refugia,within,southern,indicated,recurrent,northward,colonization,after,speciation,possibly,tracking,habitats,created,retreat,during,interglacial,periods,Common,garden,experiment,involving,perennial,conducted,over,years,revealed,significant,changes,fitness,related,traits,across,source,latitudes,altitudes,including,latitudinal,increases,survival,compactness,architecture,suggesting,gradual,range,expansion,These,findings,support,that,was,aided,environmental,Our,results,thus,provide,insight,into,evolutionary,high

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