Uplift Of Qinghai-Tibet Plateau Research Articles

Phylogenetics and biogeography of the olive family (Oleaceae).

Progress in the systematic studies of the olive family (Oleaceae) during the last two decades provides the opportunity to update its backbone phylogeny and to investigate its historical biogeography. We additionally aimed to understand the factors underlying the disjunct distribution pattern between East Asia and both West Asia and Europe that is found more commonly in this family than in any other woody plant families. Using a sampling of 298 species out of ca. 750, the largest in a phylogenetic study of Oleaceae thus far, and a set of 36 plastid and nuclear markers, we reconstructed and dated a new phylogenetic tree based on maximum likelihood and Bayesian methods and checked for any reticulation events. We also assessed the relative support of four competing hypotheses [Qinghai-Tibet Plateau uplift (QTP-only hypothesis), climatic fluctuations (Climate-only hypothesis), combined effects of QTP uplift and climate (QTP-Climate hypothesis), and no effects (Null hypothesis)] in explaining these disjunct distributions. We recovered all tribes and subtribes within Oleaceae as monophyletic, but uncertainty in the position of tribe Forsythieae remains. Based on this dataset, no reticulation event was detected. Our biogeographic analyses support the QTP-Climate hypothesis as the likely main explanation for the East-West Eurasian disjunctions in Oleaceae. Our results also show an earlier origin of Oleaceae at ca. 86 Mya and the role of Tropical Asia as a main source of species dispersals. Our new family-wide and extensive phylogenetic tree highlights both the stable relationships within Oleaceae, including the polyphyly of the genus Chionanthus, and the need for further systematic studies within the family's largest and most under-sampled genera (Chionanthus and Jasminum). Increased sampling will also help to fine-tune biogeographic analyses across spatial scales and geological times.

A global dataset on species occurrences and functional traits of Schizothoracinae fish

The Schizothoracinae fish are a natural group of cyprinids widely distributed in rivers and lakes in the Qinghai-Tibetan Plateau (QTP) and adjacent regions. These fish parallelly evolved with the QTP uplift and are thus important for uncovering geological history, the paleoclimatic environment, and the mechanisms of functional adaptation to environmental change. However, a dataset including species occurrences and functional traits, which are essential for resolving the above issues and guiding relevant conservation, remains unavailable. To fill this gap, we systematically compiled a comprehensive dataset on species occurrences and functional traits of Schizothoracinae fish from our long-term field samplings and various sources (e.g., publications and online databases). The dataset includes 7,333 occurrence records and 3,204 records of 32 functional traits covering all the genera and species of Schizothoracinae fish (i.e., 12 genera and 125 species or subspecies). Sampling records spanned over 180 years. This dataset will serve as a valuable resource for future research on the evolution, historical biogeography, responses to environmental change, and conservation of the Schizothoracinae fish.

Demographic complexity within walnut species provides insights into the heterogeneity of geological and climatic fluctuations in East Asia

AbstractEast Asia constitutes one of the largest and most complex areas of plant diversity globally. This complexity is attributable to the geological history and climatic diversity of East Asia. However, controversy persists over the biogeographical hypotheses and different studies on this topic. The demographical complexity of temperate deciduous woody plants and heterogeneity of geological and climatic fluctuations in East Asia remain poorly understood. We aimed to assemble the chloroplast and nuclear genomes of 360 individuals from five walnut (Juglans) species in East Asia and comprehensively analyze the phylogenetic inference, genetic structure, population demographic, and selection pressure. The results showed that East Asian walnuts could be divided into two major groups, that is, section Juglans/Dioscaryon and sect. Cardiocaryon. Within sect. Cardiocaryon, the samples were categorized into the northern clade and southern clade, both of which were affected by Quaternary glaciation; however, the southern clade was affected to a lesser extent. The population expansion events observed in sect. Cardiocaryon and sect. Dioscaryon since the late Miocene indicated that Neogene climate cooling substantially affected the distribution of Tertiary relict plants in East Asia. Biogeographic analysis results showed that the uplift of the Qinghai–Tibetan Plateau (QTP) might have contributed to the divergence within sect. Dioscaryon. Our findings highlight the heterogeneity of climatic fluctuations in the northern and southern regions of East Asia during the late Neogene and Quaternary periods and suggest that the uplift of QTP could have facilitated the divergence of temperate deciduous woody plants.

Landscape Heterogeneity Explains the Genetic Differentiation of a Forest Bird across the Sino-Himalayan Mountains.

Mountains are the world's most important centers of biodiversity. The Sino-Himalayan Mountains are global biodiversity hotspot due to their extremely high species richness and endemicity. Ample research investigated the impact of the Qinghai-Tibet Plateau uplift and Quaternary glaciations in driving species diversification in plants and animals across the Sino-Himalayan Mountains. However, little is known about the role of landscape heterogeneity and other environmental features in driving diversification in this region. We utilized whole genomes and phenotypic data in combination with landscape genetic approaches to investigate population structure, demography, and genetic diversity in a forest songbird species native to the Sino-Himalayan Mountains, the red-billed leiothrix (Leiothrix lutea). We identified 5 phylogeographic clades, including 1 in the East of China, 1 in Yunnan, and 3 in Tibet, roughly consistent with differences in song and plumage coloration but incongruent with traditional subspecies boundaries. Isolation-by-resistance model best explained population differentiation within L. lutea, with extensive secondary contact after allopatric isolation leading to admixture among clades. Ecological niche modeling indicated relative stability in the extent of suitable distribution areas of the species across Quaternary glacial cycles. Our results underscore the importance of mountains in the diversification of this species, given that most of the distinct genetic clades are concentrated in a relatively small area in the Sino-Himalayan Mountain region, while a single shallow clade populates vast lower-lying areas to the east. This study highlights the crucial role of landscape heterogeneity in promoting differentiation and provides a deep genomic perspective on the mechanisms through which diversity hotspots form.

Historical biogeography and evolutionary diversification of Lilium (Liliaceae): New insights from plastome phylogenomics

Here, we infer the historical biogeography and evolutionary diversification of the genus Lilium. For this purpose, we used the complete plastomes of 64 currently accepted species in the genus Lilium (14 plastomes were newly sequenced) to recover the phylogenetic backbone of the genus and a time-calibrated phylogenetic framework to estimate biogeographical history scenarios and evolutionary diversification rates of Lilium. Our results suggest that ancient climatic changes and geological tectonic activities jointly shaped the distribution range and drove evolutionary radiation of Lilium, including the Middle Miocene Climate Optimum (MMCO), the late Miocene global cooling, as well as the successive uplift of the Qinghai-Tibet Plateau (QTP) and the strengthening of the monsoon climate in East Asia during the late Miocene and the Pliocene. This case study suggests that the unique geological and climatic events in the Neogene of East Asia, in particular the uplift of QTP and the enhancement of monsoonal climate, may have played an essential role in formation of uneven distribution of plant diversity in the Northern Hemisphere.

Terrestrial paleoclimate changes recorded by Pleistocene red earth deposits at the Gaolingpo Paleolithic site, Bose Basin, South China

The Quaternary river sediments at Gaolingpo, Bose Basin, Guangxi Province contain stone hand adzes and microliths of Paleolithic and Neolithic ages, providing information about the effect of climatic and environmental changes on hominin and early modern human activities. Gaolingpo is a representative Paleolithic site in the Bose Basin, containing numerous stone artifacts of different ages in the red earth sediments. We examined the clay mineralogy and geochemistry of the Gaolingpo profile using X-ray diffractometry (XRD), diffuse reflectance spectroscopy (DRS), and X-ray fluorescence (XRF) spectroscopy with the goal of reconstructing paleoclimatic and environmental changes in the study area since the late Early Pleistocene. Within this soil profile, kaolinite and vermiculite increase and illite decreases gradually up section. The red earth sediments exhibit uniform chondrite-normalized rare earth element (REE) distribution patterns, which are similar to those of upper continental crust (UCC), post-Archean Australian shale (PAAS), loess and paleosol of the Chinese Loess Plateau (CLP), and Yangtze River deposits. These confirm that the Gaolingpo red earth sediments originated from fine materials of well-mixed weathered continental crust within the upper Pearl River drainage basin. The chemical index of alteration (CIA) of the Gaolingpo sediments is 86.4–92.1, indicating that the sediments have undergone intense chemical weathering. Based on changes in clay mineral contents and geochemical compositions through the profile, the paleoclimatic evolution of the Gaolingpo area since the late Early Pleistocene can be divided into two stages with four sub-stages: (1) a generally humid climate prevailed during stage I can be further divided in two sub-stages. Sub-stage Ia was temperate with an alternating dry and wet climate, while sub-stage Ib was a transition to a warmer temperate climate. (2) A subtropical humid climate prevailed during stage II and transitioned to a cooler climate in the later stage. In this episode, sub-stage IIa was the warmest and the most humid period since the late Early Pleistocene in Bose Basin, and Stage IIb was a transition to a relatively cooler subtropical climate. This climate pattern is compatible with the regional palynological record at Chongzuo, south Guangxi and is in general agreement with the δ18O records from cave stalagmites in southern China, but is inconsistent with the δ18O record at ODP Site 1148 in the northern part of the South China Sea, though the age constraints limit a precise correlation. This reflects the predominant influence of Qinghai-Tibetan Plateau uplift on East Asian climate since the late Early Pleistocene. The development of warm, humid, and only weakly fluctuating climate conditions in the Bose Basin was favorable for early hominin settlement.

Phylogeography of Chinese cereal cyst nematodes sheds lights on their origin and dispersal.

Reconstructing the dispersal routes of pathogens can help identify the key drivers of their evolution and provides a basis for disease control. The cereal cyst nematode Heterodera avenae is one of the major nematode pests on cereals that can cause 10%–90% crop yield losses worldwide. Through extensive sampling on wheat and grasses, the Chinese population of H. avenae is widely identified in virtually all wheat growing regions in China, with H1 being the predominant haplotype. The monoculture of wheat in north China might have been the key driver for the prevalence of H1 population, which should date no earlier than the Han Dynasty (202 BCE–220 CE). Molecular phylogenetic and biogeographic analyses of Chinese H. avenae suggest a Pleistocene northwest China origin and an ancestral host of grasses. We assume that the prosperity of Heterodera in this region is a result of their preference for cooler climate and various grass hosts, which only appeared after the uplift of Qinghai‐Tibetan Plateau and aridification of Inner Asia. Nematode samples from the current and historical floodplains show a significant role of the Yellow River in the distribution of Chinese H. avenae. Whereas mechanical harvesters that operate on an inter‐provincial basis suggest the importance in the transmission of this species in eastern China in recent times. This study highlights the role of environmental change, river dynamics, and anthropogenic factors in the origin and long‐distance dissemination of pathogens.

Phylogeographical Pattern and Population Evolution History of Indigenous Elymus sibiricus L. on Qinghai-Tibetan Plateau.

Elymus sibiricus L. is a perennial allotetraploid belonging to Triticeae of Poaceae, Elymus L., as the type species of genus Elymus L. The existing geographical distribution pattern and genetic spatial structure of E. sibiricus on Qinghai–Tibetan Plateau (QTP) are not yet clear. In this study, population genetic structure and demography history of 216 individuals from 44 E. sibiricus populations on QTP were studied used specific-locus amplified fragment sequencing (SLAF-seq). The result of genetic diversity showed that there was no single genetic diversity center was observed across all E. sibiricus populations. The results of genetic variation showed that 44 populations were clearly divided into the following three groups: Qinghai Plateau (Group I), South Tibet (Group II), and Hengduan Mountains (Group III). From the three analyses of AMOVA, Mantel test and Treemix, strong genetic differentiation across all populations and low genetic differentiation among populations within three groups. Molecular dating indicated that E. sibiricus diverged at 16.08 Ma (during the early Miocene) can be linked to the Himalayan Motion stage of QTP uplift. It is speculated that the reasons affecting the current phylogeographical pattern are as follows: (1) The environmental changes due to the uplift of the QTP; (2) The geographic distance between the populations (Groups I and III are close in geographic distance, and gene flow are frequent); (3) Geographical barriers (the Tanggula and Bayangela Mountains between Groups I and II). This study provides new evidence and historical perspective to the future exploration of the evolution and geographic distribution pattern of Elymus L.

Plastid and mitochondrial phylogenomics reveal correlated substitution rate variation in Koenigia (Polygonoideae, Polygonaceae) and a reduced plastome for Koenigia delicatula including loss of all ndh genes

Koenigia, a genus proposed by Linnaeus, has a contentious taxonomic history. In particular, relationships among species and the circumscription of the genus relative to Aconogonon remain uncertain. To explore phylogenetic relationships of Koenigia with other members of tribe Persicarieae and to establish the timing of major evolutionary diversification events, genome skimming of organellar sequences was used to assemble plastomes and mitochondrial genes from 15 individuals representing 13 species. Most Persicarieae plastomes exhibit a conserved structure and content relative to other flowering plants. However, Koenigia delicatula has lost functional copies of all ndh genes and the intron from atpF. In addition, the rpl32 gene was relocated in the K. delicatula plastome, which likely occurred via overlapping inversions or differential expansion and contraction of the inverted repeat. The highly supported but conflicting relationships between plastome and mitochondrial trees and among gene trees complicates the circumscription of Koenigia, which could be caused by rapid diversification within a short period. Moreover, the plastome and mitochondrial trees revealed correlated variation in substitution rates among Persicarieae species, suggesting a shared underlying mechanism promoting evolutionary rate variation in both organellar genomes. The divergence of dwarf K. delicatula from other Koenigia species may be associated with the well-known Eocene Thermal Maximum 2 or Early Eocene Climatic Optimum event, while diversification of the core-Koenigia clade associates with the Mid-Miocene Climatic Optimum and the uplift of Qinghai-Tibetan Plateau and adjacent areas.

Integrative taxonomy on the rare sky-island Ligidium species from southwest China (Isopoda, Oniscidea, Ligiidae)

BackgroundThe sky-island Ligidium species fauna in southwest China is poorly known. Before this study, six of the seven sky-island species of the genus were known to be endemic to southwest China. In morphology, Ligidium species are often difficult to identify, and an appraisal of integrative taxonomy is needed.ResultsWe integrated morphology and molecular analyses to delimit Ligidium species. Molecular species delimitation based on distance- and evolutionary models recovered seven-candidate lineages from five gene markers (COI, 12S rRNA, 18S rRNA, 28S rRNA and NAK). We also estimated that the species divergences of sky-island Ligidium in southwest China started in late Eocene (40.97 Mya) to middle Miocene (15.19 Mya).Four new species (L. duospinatum Li, sp. nov., L. acuminatum Li, sp. nov., L. rotundum Li, sp. nov. and L. tridentatum Li, sp. nov.) are described. Morphological confusion among L. denticulatum Shen, 1949, L. inerme Nunomura & Xie, 2000 and L. sichuanense Nunomura, 2002 is clarified by integrative taxonomy.ConclusionThis work confirms that an integrative approach to Ligidium taxonomy is fundamental for objective classification, and deduced the uplift of Qinghai-Tibetan Plateau in the late Eocene and middle Miocene as one of the principal reasons for the species divergences of sky-island Ligidium in southwest China. We also inferred that sky-island mountains have a huge reserve of higher Ligidium species diversity.

Genomic insights into zokors’ phylogeny and speciation in China

The phylogeny and speciation of subterranean zokors in China are unclear, as previous studies on morphology and limited molecular markers have generated conflicting results. This study unraveled the complex evolutionary history of eight zokor species in China based on de novo assembly at chromosome level and whole-genome sequencing of 23 populations. We found extensive phylogenetic discordances between nuclear and mitochondrial phylogenies, and different coalescent phylogenies, which could be explained by introgression and incomplete lineage sorting (ILS). The recent Qinghai-Tibet Plateau uplift (∼3.60 million y ago; Mya) drove Eospalax to speciate into clade A and clade B (∼3.22 Mya), and discordant phylogenies in this node were mainly attributed to introgression rather than ILS. Clade A rapidly diverged into three lineages due to geographical isolation and glaciation, while glaciation and C4 plant expansion contributed to the speciation of clade B. ILS contributed to the discordances of two rapidly radiated nodes rather than introgression. The effective population sizes (Ne’s) of all the species of Eospalax were affected by three glaciations. Ancient polymorphisms and divergence hitchhiking contribute to genomic islands of all the species pairs. Positively selected genes putatively related to specific inhabitation adaptations were identified, such as heart development, neurogenesis, DNA repair, and immune response. Climate, geological tectonism, and C4 vegetation shaped the adaptation and speciation of zokors in China.

Expansion of Cyclophyllidea Biodiversity in Rodents of Qinghai-Tibet Plateau and the "Out of Qinghai-Tibet Plateau" Hypothesis of Cyclophyllideans.

The Cyclophyllidea comprises the most species-rich order of tapeworms (Platyhelminthes, Cestoda) and includes species with some of the most severe health impact on wildlife, livestock, and humans. We collected seven Cyclophyllidea specimens from rodents in Qinghai-Tibet Plateau (QTP) and its surrounding mountain systems, of which four specimens in QTP were unsequenced, representing “putative new species.” Their complete mitochondrial (mt) genomes were sequenced and annotated. Phylogenetic reconstruction of partial 28S rDNA, cox1 and nad1 datasets provided high bootstrap frequency support for the categorization of three “putative new species,” assigning each, respectively, to the genera Mesocestoides, Paranoplocephala, and Mosgovoyia, and revealing that some species and families in these three datasets, which contain 291 species from nine families, may require taxonomic revision. The partial 18S rDNA phylogeny of 29 species from Taeniidae provided high bootstrap frequency support for the categorization of the “putative new species” in the genus Hydatigera. Combined with the current investigation, the other three known Taeniidae species found in this study were Taenia caixuepengi, T. crassiceps, and Versteria mustelae and may be widely distributed in western China. Estimates of divergence time based on cox1 + nad1 fragment and mt protein-coding genes (PCGs) showed that the differentiation rate of Cyclophyllidea species was strongly associated with the rate of change in the biogeographic scenarios, likely caused by the uplift of the QTP; i.e., species differentiation of Cyclophyllidea might be driven by host-parasite co-evolution caused by the uplift of QTP. We propose an “out of QTP” hypothesis for the radiation of these cyclophyllidean tapeworms.

Phylogeny, Age, and Evolution of Tribe Lilieae (Liliaceae) Based on Whole Plastid Genomes.

Tribe Lilieae, encompassing Lilium, Notholirion, Cardiocrinum, and Fritillaria, includes economically important crops with a horticultural and medicinal value. It is considered to be a core lineage of Liliaceae, but phylogenetic relationships within it, and the timing of the origin of individual clades, remain incompletely resolved. To address these issues, we reconstructed the evolutionary history of the tribe. We sequenced 45 Liliaceae plastomes and combined them with publicly available data (for a total of 139 plastomes) to explore the systematics, origin, divergence, and evolution of Lilieae. Our taxon sampling covers all ten sections of Lilium, all Cardiocrinum species, three Notholirion species, and major phylogenetic clades of Fritillaria. Our phylogenetic analysis confirms the monophyly of major sections/subgenera of Lilium and Fritillaria with strong support. We dated the origin of Lilieae to the Eocene, with genera and species radiations inferred to have occurred in the Miocene. The reconstruction of the ancestral area implies that Lilieae may have originated from the Qinghai-Tibet Plateau (QTP): the Himalayas and Hengduan Mountains and uplifting of the QTP likely promoted divergence within the tribe. Ancestral-state reconstructions of the bulb component number (including bulblets and scales) show a strong correlation with the genus-level phylogenetic diversity in Lilieae. They also predict that the most recent common ancestor of Lilieae had bulbs with numerous bulblets. Based on these observations, we predicted that climatic oscillations associated with the QTP uplift played an important role in the evolution of the Lilieae bulb. Our findings provide a well-supported picture of evolutionary relationships and a useful framework for understanding the pathway of bulb evolution within Lilieae, contributing to a better understanding of the evolutionary history of lilies.

Phylogeography and Genetic Structure of Sand Dune Specialist Stilpnolepis centiflora (Asteraceae) in Northwest China Revealed by Molecular Data

Stilpnolepis centiflora is an endemic annual herb in the Asteraceae family found across five sand deserts in Northwest China. We aimed to investigate the genetic structure of S. centiflora and attempt to link species evolution with desert formation during the Pleistocene era. We used sequence data from nuclear and chloroplast genes to investigate genetic diversity among 28 populations. We analyzed sequence data using network analysis, spatial analysis of molecular variance (SAMOVA), and a Mantel test. We then used a molecular clock to place the genetic patterns in a temporal framework and tested for signals of expansion using neutrality tests and by determining mismatch distributions. Six distinct haplotypes and 31 ribotypes were identified. Significant chloroplast DNA population subdivision was detected (GST = 0.952; NST = 0.976), but only moderate nrDNA subdivision (GST = 0.360; NST = 0.579) was detected. SAMOVA revealed four diverging groups of related haplotypes, coinciding with the boundaries of deserts. Molecular dating suggests that the clades representing different deserts diverged from 1.2 to 0.20 Ma, concordant with the Kun-Huang Movement of Qinghai Tibet Plateau uplift and a glacial event (Naynayxungla) during the Middle–Late Pleistocene. The disjunction of S. centiflora among different deserts was correspondingly reflected in the examined genetic traits with consistent spatiotemporal evolution between species and deserts. Therefore, the evolutionary dynamics of S. centiflora appear to have been driven by geological movement and climate change. The patterns described here are potentially useful to conservation biologists and may serve as a model for other sand-obligate organisms found in the deserts of Northwest China.

Inferring the Phylogeny and Divergence of Chinese Curcuma (Zingiberaceae) in the Hengduan Mountains of the Qinghai–Tibet Plateau by Reduced Representation Sequencing

Clarifying the genetic relationship and divergence among Curcuma L. (Zingiberaceae) species around the world is intractable, especially among the species located in China. In this study, Reduced Representation Sequencing (RRS), as one of the next generation sequences, has been applied to infer large scale genotyping of major Chinese Curcuma species which present little differentiation of morphological characteristics and genetic traits. The 1295 high-quality SNPs (reduced-filtered SNPs) were chosen from 997,988 SNPs of which were detected from the cleaned 437,061 loci by RRS to investigate the phylogeny and divergence among eight major Curcuma species locate in the Hengduan Mountains of the Qinghai–Tibet Plateau (QTP) in China. The results showed that all the population individuals were clustered together within species, and species were obviously separated; the clustering results were recovered in PCA (Principal Component Analysis); the phylogeny was (((((C. Phaeocaulis, C. yunnanensis), C. kwangsiensis), (C. amarissima, C. sichuanensis)), C. longa), (C. wenyujin, C. aromatica)); Curcuma in China originated around ~7.45 Mya (Million years ago) in the Miocene, and interspecific divergence appeared at ca. 4–2 Mya, which might be sped up rapidly along with the third intense uplift of QTP.

Chloroplast genomes of two Mediterranean Bupleurum species and the phylogenetic relationship inferred from combined analysis with East Asian species.

The chloroplast genomes of Mediterranean Bupleurum species are reported for the first time. Phylogenetic analysis supports the species as a basal clade of Bupleurum with divergence time at 35.40Ma. Bupleurum is one of the most species-rich genus with high medicinal value in Apiaceae. Although infrageneric classifications of Bupleurum have been the subject of numerous studies, it still remains controversial. Chloroplast genome information will prove essential in advancing our understanding on phylogenetic study. Here we report cp genomes of two woody Bupleurum species (Bupleurum gibraltaricum and B. fruticosum) endemic to Mediterranean. The complete cp genomes of the two species were 157,303 and 157,391bp in size, respectively. They encoded 114 unique genes including 30 tRNA genes, 4 rRNA genes and 80 protein coding genes. Genome structure, distributions of SDRs and SSRs, gene content exhibited similarities among Bupleurum species. High variable hotspots were detected in eight intergenic spacers and four genes. Most of genes were under purifying selection with two exceptions: atpF and clpP. The phylogenetic analysis based on 80 coding genes revealed that the genus was divided into 2 distinct clades corresponding to the 2 subgenera (subg. Penninervia, subg. Bupleurum) with divergence time at the end of collision of India with Eurasia. Most species diversified mainly during the later period of uplift of Qinghai-Tibetan Plateau. The cp genomes of the two Bupleurum species can be significant complementary to insights into the cp genome characteristics of this genus. The comparative chloroplast genomes and phylogenetic analysis advances our understanding of the evolution of cp genomes and phylogeny in Bupleurum.

Structural characteristics of central depression belt in deep-water area of the Qiongdongnan Basin and the hydrocarbon discovery of Songnan low bulge

The Qiongdongnan Basin has the first proprietary high-yield gas field in deep-water areas of China and makes the significant breakthroughs in oil and gas exploration. The central depression belt of deep-water area in the Qiongdongnan Basin is constituted by five sags, i.e. Ledong Sag, Lingshui Sag, Songnan Sag, Baodao Sag and Changchang Sag. It is a Cenozoic extensional basin with the basement of pre-Paleogene as a whole. The structural research in central depression belt of deep-water area in the Qiongdongnan Basin has the important meaning in solving the basic geological problems, and improving the exploration of oil and gas of this basin. The seismic interpretation and structural analysis in this article was operated with the 3D seismic of about 1.5×104 km2 and the 2D seismic of about 1×104 km. Eighteen sampling points were selected to calculate the fault activity rates of the No.2 Fault. The deposition rate was calculated by the ratio of residual formation thickness to deposition time scale. The paleo-geomorphic restoration was obtained by residual thickness method and impression method. The faults in the central depression belt of deep-water area of this basin were mainly developed during Paleogene, and chiefly trend in NE-SW, E-W and NW-SE directions. The architectures of these sags change regularly from east to west: the asymmetric grabens are developed in the Ledong Sag, western Lingshui Sag, eastern Baodao Sag, and western Changchang Sag; half-grabens are developed in the Songnan Sag, eastern Lingshui Sag, and eastern Changchang Sag. The tectonic evolution history in deep-water area of this basin can be divided into three stages, i.e. faulted-depression stage, thermal subsidence stage, and neotectonic stage. The Ledong-Lingshui sags, near the Red River Fault, developed large-scale sedimentary and subsidence by the uplift of Qinghai-Tibet Plateau during neotectonic stage. The Baodao-Changchang sags, near the northwest oceanic sub-basin, developed the large-scale magmatic activities and the transition of stress direction by the expansion of the South China Sea. The east sag belt and west sag belt of the deep-water area in the Qiongdongnan Basin, separated by the ancient Songnan bulge, present prominent differences in deposition filling, diaper genesis, and sag connectivity. The west sag belt has the advantages in high maturity, well-developed fluid diapirs and channel sand bodies, thus it has superior conditions for oil and gas migration and accumulation. The east sag belt is qualified by the abundant resources of oil and gas. The Paleogene of Songnan low bulge, located between the west sag belt and the east sag belt, is the exploration potential. The YL 8 area, located in the southwestern high part of the Songnan low bulge, is a favorable target for the future gas exploration. The Well 8-1-1 was drilled in August 2018 and obtained potential business discovery, and the Well YL8-3-1 was drilled in July 2019 and obtained the business discovery.

Phylogeny and genetic diversity reveal the influence of Qinghai-Tibet Plateau uplift on the divergence and distribution of Gymnocypris species

The complex environments and climatic conditions of the Qinghai-Tibet Plateau (QTP) create unique patterns of species diversity. However, the effect of uplift of the QTP on the distribution of Gymnocypris species (Gymnocypris) remain unclear. We found that the Qilian Mountain (QL) population has the highest genetic diversity by mitochondrial DNA hypervariable region of Gymnocypris species, the Tibetan (T) population has the lowest genetic diversity. The T population differs significantly from the Qinghai Lake (QH) and QL populations based on single nucleotide polymorphisms. A phylogeny and network distribution of this species on the QTP reveal differences in its genetic structure and support its taxonomic status. Neutrality tests reveal that Gymnocypris species has experienced different degrees of expansion, even secondary expansion. A divergence timetree estimates that the time of separation of different populations is possible related to uplift of the QTP and is consistent with the time of corresponding geological events. The QL population was separated from the other populations during the third uplift of the QTP (approximately 0.14 million years ago), and the QH and T populations were separated in the late Pleistocene to the Holocene (approximately 0.03 million years ago). In conclusion, this study provides different insights into the distribution of Gymnocypris species due to uplift of the QTP. Gymnocypris species was separated into different populations by this uplift, and each population exhibits unique characteristics, especially in terms of genetic structure and the degree of expansion. Moreover, the divergence time is consistent with the time of uplift of the QTP.

Species Delimitation and Evolutionary History of Tree Frogs in the Hyla chinensis Group (Hylidae, Amphibian)

Species are the cornerstone in many domains of biology research, which make the accurate species delimitation became critically important. In this study, the systematics and biogeography of the Hyla chinensis-group were analyzed based on phylogeny, species delimitation and ancestral area reconstruction methods. The phylogenetic results showed six specific clusters existed in the H. chinensis-group. BPP analysis indicated that six distinct species exist due to the high probability values (>0.95), which were also supported by the BF analysis. The divergence time of the H. chinensis-group was estimated to date back to 18.84 Mya in the early Miocene. Combining the results of ancestral area reconstruction, the H. chinensis-group might have originated from Guangxi-Hainan, then spread eastwardly and reached Nanling mountains, Wuyi mountains, Huangshan mountains and Taiwan. In rightabout colonization, it was gradually extended to the Yunnan-Guizhou Plateau, Sichuan basin, Qinling mountains and Dabie mountains. Considering the geological movement from early Miocene to Pliocene, the colonization pattern of the H. chinensis-group maybe closely related to the progressive uplift of Qinghai-Tibetan Plateau (QTP) and historical climate change. Our study provided evidence for species delimitation and speciation process within the H. chinensis-group. Our study supported the hypothesis that the evolutionary divergence in this species group was a consequence of the progressive uplift of QTP and environmental change.

Taxonomy and phylogenetic relationship of zokors

Zokor (Myospalacinae) is one of the subterranean rodents, endemic to east Asia. Due to the convergent and parallel evolution induced by its special lifestyles, the controversies in morphological classification of zokor appeared at the level of family and genus. To resolve these controversies about taxonomy and phylogeny, the phylogenetic relationships of 20 species of Muroidea and six species of zokors were studied based on complete mitochondrial genome and mitochondrial Cytb gene, respectively. Phylogeny analysis of 20 species of Muroidea indicated that the zokor belonged to the family Spalacidae, and it was closer to mole rat rather than bamboo rat. Besides, by investigating the phylogenetic relationships of six species of zokors, the status of two genera of Eospalax and Myospalax was affirmed because the two clades differentiated in phylogenetic tree represented two types of zokors, convex occiput type and flat occiput type, respectively. In addition, the two origins in Eospalax were found diverged at 3.71 million years ago (Ma) based on estimation of divergence time. It is suggested that the climate and ecology changes caused by the Qinghai-Tibet Plateau uplift event in 3.6 Ma led to the inner divergence of Eospalax. The intraspecific phylogenetic relationships of partial zokors were well resolved, the two clades of Eospalax cansus represented two geographical populations, respectively, and the divergent pattern of Eospalax baileyi was characterized by allopatric divergence spatially. In this study, we explored the taxonomic status and phylogenetic relationships of Myospalacinae at the molecular level. These works would be significant to understanding the evolutionary process and to clarify the mechanism of differentiation of Myospalacinae.