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Background and Aims Understanding adaptive genetic variation and whether it can keep pace with predicted future climate change is critical in assessing the genetic vulnerability of species and developing conservation management strategies. The lack of information on adaptive genetic variation in relict species carrying abundant genetic resources hinders the assessment of genetic vulnerability. Using a landscape genomics approach, this study aimed to determine how adaptive genetic variation shapes population divergence and to predict the adaptive potential of Pterocarya macroptera (a vulnerable relict species in China) under future climate scenarios. Methods We applied restriction site-associated DNA sequencing (RAD-seq) to obtain 8244 single-nucleotide polymorphisms (SNPs) from 160 individuals across 28 populations. We examined the pattern of genetic diversity and divergence, and then identified outliers by genetic differentiation (F ST) and genotype–environment association (GEA) methods. We further dissected the effect of geographical/environmental gradients on genetic variation. Finally, we predicted genetic vulnerability and adaptive risk under future climate scenarios. Key Results We identified three genetic lineages within P. macroptera : the Qinling-Daba-Tianmu Mountains (QDT), Western Sichuan (WS) and Northwest Yunnan (NWY) lineages, which showed significant signals of isolation by distance (IBD) and isolation by environment (IBE). IBD and IBE explained 3.7–5.7 and 8.6–12.8 % of the genetic structure, respectively. The identified GEA SNP-related genes were involved in chemical defence and gene regulation and may exhibit higher genetic variation to adapt to the environment. Gradient forest analysis revealed that the genetic variation was mainly shaped by temperature-related variables, indicating its adaptation to local thermal environments. A limited adaptive potential was suggested by the high levels of genetic vulnerability in marginal populations. Conclusions Environmental gradient mainly shaped the population differentiation of P. macroptera. Marginal populations may be at high risk of extinction, and thus proactive management measures, such as assisted gene flow, are required to ensure the survival of these populations. [ABSTRACT FROM AUTHOR]

Since the Anthropocene, biodiversity loss owing to human activity and climate change has worsened. Quercus gilva is an evergreen oak species native to China, Japan, and South Korea and is threatened by a long history of human impact. The purpose of this study was to (1) reassess the threatened category of Q. gilva based on a detailed survey, and (2) identify the genetic structure and diversity of Q. gilva based on genomic data. First, we conducted a detailed survey of the populations in China. Second, we collated all the literature and information. Finally, genome-wide genetic variation was analyzed based on 65 individuals from 22 populations. We found that Q. gilva has suffered rapid population decline, and at present, most populations are very small. The evolutionary path of Q. gilva was from the southwest to east of China and then to Japan and South Korea. Quercus gilva showed no distinct genetic structure and had a relatively low genetic diversity. Among the 22 populations, most populations in southwestern China, South Korea, and Japan had high genetic diversity. The populations in Jingning (Zhejiang province; ZJN), Wuyuan (Jinaxi province; JWY), and Zherong (Fujian province; FZR) suffered a strong bottleneck. In conclusion, Q. gilva is an endangered species native to East Asia. Because of the very low genetic diversity of Q. gilva and most populations are small, we need to (1) strengthen the protection of this species, (2) conduct conservation actions with in-situ reinforcement populations, and (3) select populations with high genetic diversity as provenances for afforestation efforts. Finally, we suggest that in the future, genetic diversity should be considered as the sixth criterion for IUCN to evaluate the threatened category. [ABSTRACT FROM AUTHOR]

Quercus litseoides, an endangered montane cloud forest species, is endemic to southern China. To understand the genomic features, phylogenetic relationships, and molecular evolution of Q. litseoides, the complete chloroplast (cp) genome was analyzed and compared in Quercus section Cyclobalanopsis. The cp genome of Q. litseoides was 160,782 bp in length, with an overall guanine and cytosine (GC) content of 36.9%. It contained 131 genes, including 86 protein-coding genes, eight ribosomal RNA genes, and 37 transfer RNA genes. A total of 165 simple sequence repeats (SSRs) and 48 long sequence repeats with A/T bias were identified in the Q. litseoides cp genome, which were mainly distributed in the large single copy region (LSC) and intergenic spacer regions. The Q. litseoides cp genome was similar in size, gene composition, and linearity of the structural region to those of Quercus species. The non-coding regions were more divergent than the coding regions, and the LSC region and small single copy region (SSC) were more divergent than the inverted repeat regions (IRs). Among the 13 divergent regions, 11 were in the LSC region, and only two were in the SSC region. Moreover, the coding sequence (CDS) of the six protein-coding genes (rps12, matK, atpF, rpoC2, rpoC1, and ndhK) were subjected to positive selection pressure when pairwise comparison of 16 species of Quercus section Cyclobalanopsis. A close relationship between Q. litseoides and Quercus edithiae was found in the phylogenetic analysis of cp genomes. Our study provided highly effective molecular markers for subsequent phylogenetic analysis, species identification, and biogeographic analysis of Quercus. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three types of magnetite were identified in the Hongniu–Hongshan skarn deposit. • Mt-type 2 show CDR texture, and the infiltration of saline hydrothermal fluids is considered to enhance CDR processes in the skarn deposit. • The crystallization of magnetite would lead to a reducing environment and was favorable for the precipitation of Cu sulfides in the later. The Hongniu–Hongshan Cu skarn deposit is located in the central part of the Zhongdian porphyry and skarn Cu belt in southwestern China. We investigated the petrography and trace-element chemistry of magnetite in the deposit to examine the nature and origin of the ore-forming fluids. Three types of magnetite were identified in porphyritic granite and skarn in the Hongniu–Hongshan deposit. Mt-type1 crystallized from magmas, is typical magmatic magnetite. Mt-type2 formed later than type1, but earlier than the syn-ore stage, and was related to magmatic–hydrothermal activity. Mt-type3 formed during the early syn-ore stage, is hydrothermal skarn magnetite. The magnetites have variable K, Mg, Al, Ti, V, Cr, Mn, Co, Ni, Cu, Pb, Zn, Ga, W, Sn, and Ge contents. The high contents of Ti, V and Cr in the Mt-type1 is largely controlled by its magmatic origin. For the type 2 magnetites, the high Al, Ti, and Ga contents were controlled by hydrothermal fluid composition and temperature, and V, Sn, and Cr were controlled by f O 2 values. The enrichment of Mg, Mn, and Zn in the Mt-type3 was largely due to fluid–rock interactions. Co-precipitating mineral phases appear to have exerted less control on magnetite compositions in the deposit. Some of the Mt-type2 had experienced coupled dissolution and reprecipitation (CDR) processes. The infiltration of saline hydrothermal fluids is considered to enhance CDR processes in the skarn deposit. We suggest that the crystallization of magnetite in the porphyritic granite reduced the sulfate content of the magma, which resulted in Cu and Au being complexed more readily into fluids. The precipitation of Mt-type3 might have resulted in a change from an oxidized to a more reduced environment, thereby creating conditions favorable for the precipitation of Cu sulfides. [ABSTRACT FROM AUTHOR]