Living gymnosperms comprise four major groups:cycads,Ginkgo,conifers,and gnetophytes.Relationships among/within these lineages have not been fully resolved.Next generation sequencing has made available a large number ...Living gymnosperms comprise four major groups:cycads,Ginkgo,conifers,and gnetophytes.Relationships among/within these lineages have not been fully resolved.Next generation sequencing has made available a large number of sequences,including both plastomes and single-copy nuclear genes,for reconstruction of solid phylogenetic trees.Recent advances in gymnosperm phylogenomic studies have updated our knowledge of gymnosperm systematics.Here,we review major advances of gymnosperm phylogeny over the past 10 years and propose an updated classification of extant gymnosperms.This new classification includes three classes(Cycadopsida,Ginkgoopsida,and Pinopsida),five subclasses(Cycadidae,Ginkgoidae,Cupressidae,Pinidae,and Gnetidae),eight orders(Cycadales,Ginkgoales,Araucariales,Cupressales,Pinales,Ephedrales,Gnetales,and Welwitschiales),13 families,and 86 genera.We also described six new tribes including Acmopyleae Y.Yang,Austrocedreae Y.Yang,Chamaecyparideae Y.Yang,Microcachrydeae Y.Yang,Papuacedreae Y.Yang,and Prumnopityeae Y.Yang,and made 27 new combinations in the genus Sabina.展开更多
Tissues of the pinna and rachis of Cycas diannaensis and pinna, rachis, and root of Cycas taiwaniana, rachis of Cycas szechuanensis, stem of Metasequoia glyptostroboides (Taxodiaceae), stems of Chamaecyparis obtusa (S...Tissues of the pinna and rachis of Cycas diannaensis and pinna, rachis, and root of Cycas taiwaniana, rachis of Cycas szechuanensis, stem of Metasequoia glyptostroboides (Taxodiaceae), stems of Chamaecyparis obtusa (Sieb.et Zucc.) Endl cv. Tetragona (Cupressaceae), and leaves and stems of Michelia alba and Michelia figo and stems of Amygdalus persica (angiosperms) were compared using the scanning electron microscopy. In all species of these gymnosperms, their many tracheary elemnts have perforations in end walls and lateral walls. These structures are the same as vessels of angiosperms;therefore, these tracheary elements are vessel elements. Many types of vessels were found in cycads: pitted vessels in M. glyptostroboides, spiral and pitted vessels in Chamaecyparis obtusa cv. Tetragona. The development and structural characteristics of vessels of cycads, the two other gymnosperms, and the angiosperms were identical. Some characters such as extent of incline of perforation plate in the end wall showed that vessel characters of some angiosperms were more primitive than the cycads or M. glyptostroboides and C. obtusa cv. Tetragona. Many of the vessel elements of the angiosperms were band shaped, without end walls, and had only two lateral walls and other two margins;the end was acuate or with an arc margin;the end of some vessel elements was acute with no perforations, many perforations located only in lateral wall. Such results are rarely reported in previous work. In all species, perforations were seen only in tracheae, and the walls of parenchyma cells only had a thin primary wall and without perforation. Analysis and discussion to the experimental measures which were observed and research of the structure of vessel or tracheid, pointed out that several measures all could be used and the Jeffrey’ method effects were better. Comparing the vessels of cycads, Taxodiaceae and Cupressaceae helps us to understand the mechanism in which these most primitive or more primitive extant gymnosperms were adapted to harsh environments and to understand these species’ evolutionary extent, and has the significance to the studies of plant anatomy, plant systematics and plant evolution.展开更多
The effect of evolutionary history on wood density variation may play an important role in shaping variation in wood density,but this has largely not been tested.Using a comprehensive global dataset including 27,297 m...The effect of evolutionary history on wood density variation may play an important role in shaping variation in wood density,but this has largely not been tested.Using a comprehensive global dataset including 27,297 measurements of wood density from 2621 tree species worldwide,we test the hypothesis that the legacy of evolutionary history plays an important role in driving the variation of wood density among tree species.We assessed phylogenetic signal in different taxonomic(e.g.,angiosperms and gymnosperms)and ecological(e.g.,tropical,temperate,and boreal)groups of tree species,explored the biogeographical and phylogenetic patterns of wood density,and quantified the relative importance of current environmental factors(e.g.,climatic and soil variables)and evolutionary history(i.e.,phylogenetic relatedness among species and lineages)in driving global wood density variation.We found that wood density displayed a significant phylogenetic signal.Wood density differed among different biomes and climatic zones,with higher mean values of wood density in relatively drier regions(highest in subtropical desert).Our study revealed that at a global scale,for angiosperms and gymnosperms combined,phylogeny and species(representing the variance explained by taxonomy and not direct explained by long-term evolution process)explained 84.3%and 7.7%of total wood density variation,respectively,whereas current environment explained 2.7%of total wood density variation when phylogeny and species were taken into account.When angiosperms and gymnosperms were considered separately,the three proportions of explained variation are,respectively,84.2%,7.5%and 6.7%for angiosperms,and 45.7%,21.3%and 18.6%for gymnosperms.Our study shows that evolutionary history outpaced current environmental factors in shaping global variation in wood density.展开更多
Main characteristics of the Permian redbed gymnosperms in North China have been summarized: dominant peltasperms and conifers, numerous enigmatics such as Gigantonoclea and Psygmophyllum, and abundant precursors of Me...Main characteristics of the Permian redbed gymnosperms in North China have been summarized: dominant peltasperms and conifers, numerous enigmatics such as Gigantonoclea and Psygmophyllum, and abundant precursors of Mesozoic gymnosperms. Furthermore, stresses affecting these plants survival are suggested to be paleoatmospheric CO-2 concentration, water stress, wind and fire activities, and fungal infection. Consequently, a preliminary analysis accounts for the ecological strategies of these gymnosperms to the P-Tr event.展开更多
基金supported by the National Natural Science Foundation of China(31970205,31870206)the Metasequoia funding of the Nanjing Forestry University,China。
文摘Living gymnosperms comprise four major groups:cycads,Ginkgo,conifers,and gnetophytes.Relationships among/within these lineages have not been fully resolved.Next generation sequencing has made available a large number of sequences,including both plastomes and single-copy nuclear genes,for reconstruction of solid phylogenetic trees.Recent advances in gymnosperm phylogenomic studies have updated our knowledge of gymnosperm systematics.Here,we review major advances of gymnosperm phylogeny over the past 10 years and propose an updated classification of extant gymnosperms.This new classification includes three classes(Cycadopsida,Ginkgoopsida,and Pinopsida),five subclasses(Cycadidae,Ginkgoidae,Cupressidae,Pinidae,and Gnetidae),eight orders(Cycadales,Ginkgoales,Araucariales,Cupressales,Pinales,Ephedrales,Gnetales,and Welwitschiales),13 families,and 86 genera.We also described six new tribes including Acmopyleae Y.Yang,Austrocedreae Y.Yang,Chamaecyparideae Y.Yang,Microcachrydeae Y.Yang,Papuacedreae Y.Yang,and Prumnopityeae Y.Yang,and made 27 new combinations in the genus Sabina.
文摘Tissues of the pinna and rachis of Cycas diannaensis and pinna, rachis, and root of Cycas taiwaniana, rachis of Cycas szechuanensis, stem of Metasequoia glyptostroboides (Taxodiaceae), stems of Chamaecyparis obtusa (Sieb.et Zucc.) Endl cv. Tetragona (Cupressaceae), and leaves and stems of Michelia alba and Michelia figo and stems of Amygdalus persica (angiosperms) were compared using the scanning electron microscopy. In all species of these gymnosperms, their many tracheary elemnts have perforations in end walls and lateral walls. These structures are the same as vessels of angiosperms;therefore, these tracheary elements are vessel elements. Many types of vessels were found in cycads: pitted vessels in M. glyptostroboides, spiral and pitted vessels in Chamaecyparis obtusa cv. Tetragona. The development and structural characteristics of vessels of cycads, the two other gymnosperms, and the angiosperms were identical. Some characters such as extent of incline of perforation plate in the end wall showed that vessel characters of some angiosperms were more primitive than the cycads or M. glyptostroboides and C. obtusa cv. Tetragona. Many of the vessel elements of the angiosperms were band shaped, without end walls, and had only two lateral walls and other two margins;the end was acuate or with an arc margin;the end of some vessel elements was acute with no perforations, many perforations located only in lateral wall. Such results are rarely reported in previous work. In all species, perforations were seen only in tracheae, and the walls of parenchyma cells only had a thin primary wall and without perforation. Analysis and discussion to the experimental measures which were observed and research of the structure of vessel or tracheid, pointed out that several measures all could be used and the Jeffrey’ method effects were better. Comparing the vessels of cycads, Taxodiaceae and Cupressaceae helps us to understand the mechanism in which these most primitive or more primitive extant gymnosperms were adapted to harsh environments and to understand these species’ evolutionary extent, and has the significance to the studies of plant anatomy, plant systematics and plant evolution.
基金supported by the Scientific Research Project of Anhui Province(2022AH050873)the State Key Laboratory of Subtropical Silviculture(SKLSS-KF2023-08)+1 种基金the Provincial Natural Resources Fund(1908085QC140)the National Key R&D Program of China(2018YFD1000600).
文摘The effect of evolutionary history on wood density variation may play an important role in shaping variation in wood density,but this has largely not been tested.Using a comprehensive global dataset including 27,297 measurements of wood density from 2621 tree species worldwide,we test the hypothesis that the legacy of evolutionary history plays an important role in driving the variation of wood density among tree species.We assessed phylogenetic signal in different taxonomic(e.g.,angiosperms and gymnosperms)and ecological(e.g.,tropical,temperate,and boreal)groups of tree species,explored the biogeographical and phylogenetic patterns of wood density,and quantified the relative importance of current environmental factors(e.g.,climatic and soil variables)and evolutionary history(i.e.,phylogenetic relatedness among species and lineages)in driving global wood density variation.We found that wood density displayed a significant phylogenetic signal.Wood density differed among different biomes and climatic zones,with higher mean values of wood density in relatively drier regions(highest in subtropical desert).Our study revealed that at a global scale,for angiosperms and gymnosperms combined,phylogeny and species(representing the variance explained by taxonomy and not direct explained by long-term evolution process)explained 84.3%and 7.7%of total wood density variation,respectively,whereas current environment explained 2.7%of total wood density variation when phylogeny and species were taken into account.When angiosperms and gymnosperms were considered separately,the three proportions of explained variation are,respectively,84.2%,7.5%and 6.7%for angiosperms,and 45.7%,21.3%and 18.6%for gymnosperms.Our study shows that evolutionary history outpaced current environmental factors in shaping global variation in wood density.
文摘Main characteristics of the Permian redbed gymnosperms in North China have been summarized: dominant peltasperms and conifers, numerous enigmatics such as Gigantonoclea and Psygmophyllum, and abundant precursors of Mesozoic gymnosperms. Furthermore, stresses affecting these plants survival are suggested to be paleoatmospheric CO-2 concentration, water stress, wind and fire activities, and fungal infection. Consequently, a preliminary analysis accounts for the ecological strategies of these gymnosperms to the P-Tr event.
