The Indo-Burma Biodiversity Hotspot is renowned for its rich biodiversity,including that of vascular plants.However,the fern diversity and its endemism in this hotspot have not been well understood and so far,the dive...The Indo-Burma Biodiversity Hotspot is renowned for its rich biodiversity,including that of vascular plants.However,the fern diversity and its endemism in this hotspot have not been well understood and so far,the diversity of very few groups of ferns in this region has been explored using combined molecular and morphological approaches.Here,we updated the plastid phylogeny of the Java fern genus Leptochilus with 226(115%increase of the latest sampling)samples across the distribution range,specifically those of three phylogenetically significant species,Leptochilus ovatus,L.pedunculatus,and L.pothifolius.We also reconstructed the first nuclear phylogeny of the genus based on pgiC gene data.Based on molecular and morphological evidence,we identified three new major clades and six new subclades,redefined three existing species,discovered a number of cryptic species of the genus,and elucidated the evolution of the three most variable characters.Our divergence time analyses and ancestral area reconstruction showed that Leptochilus originated in the Oligocene and diversified from early Miocene and 15 dispersal events from lower to higher latitudes are identified.The evolution of three most important morphological characters is analyzed in a context of the new phylogeny.Our analysis showed that 30(59%of total 51)species of Leptochilus occur in Indo-Burma hotspot,24(80%of the 30 species)of which are endemic to this hotspot.We argue that the Indo-Burma hotspot should be recognized as a diversity hotspot for ferns.展开更多
Selaginella is the largest and most taxonomically complex genus in lycophytes.The fact that over 750 species are currently treated in a single genus makes Selaginellales/Selaginellaceae unique in pteridophytes.Here we...Selaginella is the largest and most taxonomically complex genus in lycophytes.The fact that over 750 species are currently treated in a single genus makes Selaginellales/Selaginellaceae unique in pteridophytes.Here we assembled a dataset of six existing and newly sampled plastid and nuclear loci with a total of 684 accessions(74%increase of the earlier largest sampling)representing ca.300 species to infer a new phylogeny.The evolution of 10 morphological characters is studied in the new phylogenetic context.Our major results include:(1)the nuclear and plastid phylogenies are congruent with each other and combined analysis well resolved and strongly supported the relationships of all but two major clades;(2)the Sinensis group is resolved as sister to S.subg.Pulviniella with strong support in two of the three analyses;(3)most morphological characters are highly homoplasious but some characters alone or combinations of characters well define the major clades in the family;and(4)an infrafamilial classification of Selaginellaceae is proposed and the currently defined Selaginella s.l.is split into seven subfamilies(corresponding to the current six subgenera t the Sinensis group)and 19 genera(the major diagnosable clades)with nine new species-poor genera.We support the conservation of Selaginella with a new type,S.flabellata,to minimize nomenclatural instability.We provide a key to subfamilies and genera,images illustrating their morphology,their morphological and geographical synopses,a list of constituent species,and necessary new combinations.This new classification will hopefully facilitate communication,promote further studies,and help conservation.展开更多
CO2reservoirs are widely distributed within the Yingcheng Formation in the Songliao Basin, but the extreme horizontal heterogeneity of CO2content causes difficulties in the exploration and exploitation of methane. For...CO2reservoirs are widely distributed within the Yingcheng Formation in the Songliao Basin, but the extreme horizontal heterogeneity of CO2content causes difficulties in the exploration and exploitation of methane. Former studies have fully covered the lithology, structure, and distribution of the reservoirs high in CO2content, but few are reported about migration and accumulation of CO2. Using the East Changde Gas Field as an example, we studied the accumulation mechanisms of CO2 gas. Two original types of accumulation model are proposed in this study. The fault-controlled accumulation model refers to gas accumulation in the reservoir body that is cut by a basement fault(the West Xu Fault), allowing the hydrocarbon gas generated in the lower formation to migrate into the reservoir body through the fault, which results in a relatively lower CO2content. The volcanic conduit-controlled accumulation model refers to a reservoir body that is not cut by the basement fault, which prevents the hydrocarbon gas from being mixed in and leads to higher CO2contents. This conclusion provides useful theories for prediction of CO2distribution in similar basins and reservoirs.展开更多
基金supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0502)a grant from Yunnan Fundamental Research Projects(Grant#202201BC070001)a Yunnan Revitalization Talent Support Program“Young Talent”Project and a CAS Scholarship to Liang Zhang.
文摘The Indo-Burma Biodiversity Hotspot is renowned for its rich biodiversity,including that of vascular plants.However,the fern diversity and its endemism in this hotspot have not been well understood and so far,the diversity of very few groups of ferns in this region has been explored using combined molecular and morphological approaches.Here,we updated the plastid phylogeny of the Java fern genus Leptochilus with 226(115%increase of the latest sampling)samples across the distribution range,specifically those of three phylogenetically significant species,Leptochilus ovatus,L.pedunculatus,and L.pothifolius.We also reconstructed the first nuclear phylogeny of the genus based on pgiC gene data.Based on molecular and morphological evidence,we identified three new major clades and six new subclades,redefined three existing species,discovered a number of cryptic species of the genus,and elucidated the evolution of the three most variable characters.Our divergence time analyses and ancestral area reconstruction showed that Leptochilus originated in the Oligocene and diversified from early Miocene and 15 dispersal events from lower to higher latitudes are identified.The evolution of three most important morphological characters is analyzed in a context of the new phylogeny.Our analysis showed that 30(59%of total 51)species of Leptochilus occur in Indo-Burma hotspot,24(80%of the 30 species)of which are endemic to this hotspot.We argue that the Indo-Burma hotspot should be recognized as a diversity hotspot for ferns.
基金partially supported by the Natural Science Foundation of China (#31900186,#32260050)Yunnan Fundamental Research Projects (Grant NO.202301BF07001-016)the Glory Light International Fellowship for Chinese Botanists at Missouri Botanical Garden (MO) to X.M.Zhou
文摘Selaginella is the largest and most taxonomically complex genus in lycophytes.The fact that over 750 species are currently treated in a single genus makes Selaginellales/Selaginellaceae unique in pteridophytes.Here we assembled a dataset of six existing and newly sampled plastid and nuclear loci with a total of 684 accessions(74%increase of the earlier largest sampling)representing ca.300 species to infer a new phylogeny.The evolution of 10 morphological characters is studied in the new phylogenetic context.Our major results include:(1)the nuclear and plastid phylogenies are congruent with each other and combined analysis well resolved and strongly supported the relationships of all but two major clades;(2)the Sinensis group is resolved as sister to S.subg.Pulviniella with strong support in two of the three analyses;(3)most morphological characters are highly homoplasious but some characters alone or combinations of characters well define the major clades in the family;and(4)an infrafamilial classification of Selaginellaceae is proposed and the currently defined Selaginella s.l.is split into seven subfamilies(corresponding to the current six subgenera t the Sinensis group)and 19 genera(the major diagnosable clades)with nine new species-poor genera.We support the conservation of Selaginella with a new type,S.flabellata,to minimize nomenclatural instability.We provide a key to subfamilies and genera,images illustrating their morphology,their morphological and geographical synopses,a list of constituent species,and necessary new combinations.This new classification will hopefully facilitate communication,promote further studies,and help conservation.
基金founded by the S&T development project ‘‘Key Factors Controlling Accumulation in Old Petroleum System (No. 2016A-0206)’’ by the China National Petroleum Corporation
文摘CO2reservoirs are widely distributed within the Yingcheng Formation in the Songliao Basin, but the extreme horizontal heterogeneity of CO2content causes difficulties in the exploration and exploitation of methane. Former studies have fully covered the lithology, structure, and distribution of the reservoirs high in CO2content, but few are reported about migration and accumulation of CO2. Using the East Changde Gas Field as an example, we studied the accumulation mechanisms of CO2 gas. Two original types of accumulation model are proposed in this study. The fault-controlled accumulation model refers to gas accumulation in the reservoir body that is cut by a basement fault(the West Xu Fault), allowing the hydrocarbon gas generated in the lower formation to migrate into the reservoir body through the fault, which results in a relatively lower CO2content. The volcanic conduit-controlled accumulation model refers to a reservoir body that is not cut by the basement fault, which prevents the hydrocarbon gas from being mixed in and leads to higher CO2contents. This conclusion provides useful theories for prediction of CO2distribution in similar basins and reservoirs.