Cryptic species are commonly misidentified because of high morphological similarities to other species.One group of plants that may harbor large numbers of cryptic species is the quillworts(Isoetes spp.),an ancient aq...Cryptic species are commonly misidentified because of high morphological similarities to other species.One group of plants that may harbor large numbers of cryptic species is the quillworts(Isoetes spp.),an ancient aquatic plant lineage.Although over 350 species of Isoetes have been reported globally,only ten species have been recorded in China.The aim of this study is to better understand Isoetes species diversity in China.For this purpose,we systematically explored the phylogeny and evolution of Isoetes using complete chloroplast genome(plastome)data,spore morphology,chromosome number,genetic structure,and haplotypes of almost all Chinese Isoetes populations.We identified three ploidy levels of Isoetes in Chinaddiploid(2n=22),tetraploid(2n=44),and hexaploid(2n=66).We also found four megaspore and microspore ornamentation types in diploids,six in tetraploids,and three in hexaploids.Phylogenetic analyses confirmed that I.hypsophila as the ancestral group of the genus and revealed that Isoetes diploids,tetraploids,and hexaploids do not form monophyletic clades.Most individual species possess a single genetic structure;however,several samples have conflicting positions on the phylogenetic tree based on SNPs and the tree based on plastome data.All 36 samples shared 22 haplotypes.Divergence time analysis showed that I.hypsophila diverged in the early Eocene(~48.05 Ma),and most other Isoetes species diverged 3-20 Ma.Additionally,different species of Isoetes were found to inhabit different water systems and environments along the Yangtze River.These findings provide new insights into the relationships among Isoetes species in China,where highly similar morphologic populations may harbor many cryptic species.展开更多
The authors investigated the genetic diversity of 29 natural populations representing Pinus yunnanensis Franch. and its two close relatives, P. densata Mast. and P. kesiya Royle ex Gordn. var. langbianensis (A Chey.) ...The authors investigated the genetic diversity of 29 natural populations representing Pinus yunnanensis Franch. and its two close relatives, P. densata Mast. and P. kesiya Royle ex Gordn. var. langbianensis (A Chey.) Gaussen. Horizontal starch gel electrophoresis was performed for macrogametophytes collected from populations in Yunnan, Sichuan and Guangxi. Allozyme data for 33 loci of 14 enzymes demonstrated high levels of genetic variation at both population and species levels in comparison with other conifers, with the mean values for populations being P=0.694, A =2.0 and He =0.145 for P. yunnanensis; P=0.714, A=2.0 and He =0.174 for P. densata ; and P=0.758, A=2.1 and He =0.184 for P. kesiya var. langbianensis. Based on Wright’s F _statistics, the fixation index of P. yunnanensis, P. densata and P. kesiya var. langbianensis were 0.101, 0.054 and 0.143, respectively, indicating that the populations were largely under random mating. Based on Nei’s genetic distance, the genetic differentiation was not obvious among the three species (i.e. the genetic distance was less than 0.075). Because of the wider distribution of P. yunnanensis with greater variety of habitats, it was shown that the genetic differentiation among the P. yunnanensis populations was larger than that of the populations of the other two species. According to morphological, geographic and allozymic evidences, the authors suggested that the three species be better treated as varieties under a single species. In addition, the extensive gene flow among the three pine species resulted in great genetic diversity and evolutionary potential. Also, high level of genetic variation of P. yunnanensis provides important basis for its genetic improvement and breeding in future.展开更多
基金This study was supported by the Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization(grant number OC202103)the Harbin Normal University Postgraduate Innovation Project(grant number HSDBSCX2021-01)+1 种基金the National Natural Science Foundation of China General Projects(grant number 32170216)the Hangzhou Science and Technology Development Project(grant number 20201203B113).
文摘Cryptic species are commonly misidentified because of high morphological similarities to other species.One group of plants that may harbor large numbers of cryptic species is the quillworts(Isoetes spp.),an ancient aquatic plant lineage.Although over 350 species of Isoetes have been reported globally,only ten species have been recorded in China.The aim of this study is to better understand Isoetes species diversity in China.For this purpose,we systematically explored the phylogeny and evolution of Isoetes using complete chloroplast genome(plastome)data,spore morphology,chromosome number,genetic structure,and haplotypes of almost all Chinese Isoetes populations.We identified three ploidy levels of Isoetes in Chinaddiploid(2n=22),tetraploid(2n=44),and hexaploid(2n=66).We also found four megaspore and microspore ornamentation types in diploids,six in tetraploids,and three in hexaploids.Phylogenetic analyses confirmed that I.hypsophila as the ancestral group of the genus and revealed that Isoetes diploids,tetraploids,and hexaploids do not form monophyletic clades.Most individual species possess a single genetic structure;however,several samples have conflicting positions on the phylogenetic tree based on SNPs and the tree based on plastome data.All 36 samples shared 22 haplotypes.Divergence time analysis showed that I.hypsophila diverged in the early Eocene(~48.05 Ma),and most other Isoetes species diverged 3-20 Ma.Additionally,different species of Isoetes were found to inhabit different water systems and environments along the Yangtze River.These findings provide new insights into the relationships among Isoetes species in China,where highly similar morphologic populations may harbor many cryptic species.
文摘The authors investigated the genetic diversity of 29 natural populations representing Pinus yunnanensis Franch. and its two close relatives, P. densata Mast. and P. kesiya Royle ex Gordn. var. langbianensis (A Chey.) Gaussen. Horizontal starch gel electrophoresis was performed for macrogametophytes collected from populations in Yunnan, Sichuan and Guangxi. Allozyme data for 33 loci of 14 enzymes demonstrated high levels of genetic variation at both population and species levels in comparison with other conifers, with the mean values for populations being P=0.694, A =2.0 and He =0.145 for P. yunnanensis; P=0.714, A=2.0 and He =0.174 for P. densata ; and P=0.758, A=2.1 and He =0.184 for P. kesiya var. langbianensis. Based on Wright’s F _statistics, the fixation index of P. yunnanensis, P. densata and P. kesiya var. langbianensis were 0.101, 0.054 and 0.143, respectively, indicating that the populations were largely under random mating. Based on Nei’s genetic distance, the genetic differentiation was not obvious among the three species (i.e. the genetic distance was less than 0.075). Because of the wider distribution of P. yunnanensis with greater variety of habitats, it was shown that the genetic differentiation among the P. yunnanensis populations was larger than that of the populations of the other two species. According to morphological, geographic and allozymic evidences, the authors suggested that the three species be better treated as varieties under a single species. In addition, the extensive gene flow among the three pine species resulted in great genetic diversity and evolutionary potential. Also, high level of genetic variation of P. yunnanensis provides important basis for its genetic improvement and breeding in future.
