Palynology And Biogeography Of Anaphalis

Anaphalis DC belongs to the tribe Gnaphalieae,family Asteraceae,which is the largest genus distributed in the northern hemisphere and has about 110 species in the world,with the highest diversity in the Himalayasn region.There are many controversy in systematic relationship between Anaphalis species and related genus,due to its large number of species,habitat in montane meadow,variety of morphological traits,including mature leaf,capitulum,phyllary,floret and achene,with network evolution of morphological characteristics,hybridization and polyploidization phenomenon.Furthermore,as the North temperate distribution type of plant groups,Anaphalis has the clear geographical history,which provides important research value for the biogeographical study of related genera.However,there are still few reports on the biogeography of Anaphalis.On the basis of previous studies,this study researches Anaphalis pollen grains surface micromorphological characteristics and the molecular phylogeny based on chloroplast genes and nuclear ribosome gene fragments,in order to explore the palynological characteristics and their systematic significance of the phylogenetic relationship between the genus and its relatives,and to reconstruct the Anaphalis biogeographic history,so as to provide a basis for the study of the plant diversity and the biogeographic history of the tribe Gnaphalieae in the world.The main results of this study were as follows:1.Pollen grains surface micromorphological characteristics research of AnaphalisIn this study,the surface micromorphological characteristics of pollen grains in44 groups of 34 species of Anaphalis were observed by scanning electron microscope,and researched the surface characteristics of pollen walls such as polar axis,equatorial diameter,spine length,and spine width.It was concluded that Anaphalis pollen grains belong to N₃P₄C₅type of NPC classification system.According to the surface micromorphology of the pollen grains,Anaphalis were divided into two types:Type?is with sparse obtuse spines,including A.contorta,A.margaritacea and A.morrisonicola from ser.Margaripes?DC.?Boiss.,and all species of ser.Nepalenses Ling.Pollen grains with tricolporate,P:13.83-25.46?m,E:12.89-22.03?m,P/E:1.05-1.13,subprolate in shape classes and obtuse spines in surface,CL:9.14-15.18?m,distinct edges,and the number of spines per 100 square micron varied from 7-9.Type?is with dense acute spines,including Subgen.Gnaphaliops Ling,ser.Busuae Ling,A.contortiformis from ser.Margaripes?DC.?Boiss.,and all species from ser.Sinicae Ling.,ser.Suffruticosae Ling.,ser.Flavescentes Ling.,ser.Xylorhizae Ling.and ser.Pennosae Ling.Pollen grains with tricolporate,P:12.77-23.11?m,E:8.85-23.49?m,P/E:1.14-1.16,prolate-spheroidal in shape and acute spines in surface,CL:6.67-14.41?m,distinct edges,and the number of spines per 100 square micron varied from 10-14.Type?with dense acute spines is the relative evolution pollen type.A key to the species of Anaphalis based on pollen grains surface micromorphological characteristics is presented.The results did not support traditional classification of Anaphalis sections and series based on macro-morphological characters.2 Molecular phylogeny and biogeography of AnaphalisIn this study,we used 3 chloroplast DNA sequences,including ndh F,psb A-trn H?psb A?,trn L-trn F intergenic spacer,and 2 nr DNA sequences,including ETS,ITS,from 83 taxa?belong to 59 species?Anaphalis to construct phylogenetic trees,combined with geographical distribution to infer the biogeographic history of Anaphalis.The results of molecular systematics indicated that:1)Anaphalis is clustered into one branch,which is divided into two branches with higher support rate:?.?BS=95%,PP=1?,including Ser.Margaripes?DC.?Boiss.,Ser.Busuae Ling,Ser.Oxyphyllae Ling,Ser.Nepalenses Ling;?.?BS=95%,PP=1?,including Subgen.Gnaphaliops Ling,Ser.,Ser.Sinicae Ling,Ser.Suffruticosae Ling,Ser.Xylorhizae Ling,Ser.Xylorhizae Ling,Ser.Pannosae Ling and Ser.Flavescentes Ling.?.of pollen grains type for sparse obtuse spines;?.of pollen grains type for dense acute spines.2)According to the estimation based on the calibration information of compositae fossils,Anaphalis diverged in the middle Miocene?5.33-23Ma?and the age of its crown was 11.36 Ma,and then there are branches of two ancestral groups with different differentiation times:the node H has crown age of 9.02 Ma?95%HPD:4.71-14.19?,which originated from A.brevifolia,and ended with A.surculosa;the node I is 9.07 Ma?95%HPD:5.15-14.84?,which originated from A.subdecurrens and eventually differentiated into other Anaphalis taxa.3)Reconstruction of the ancestral region shows that Anaphalis colonized the southwestern Himalayas and then spread to southeast Asia and North America.