Characteristics of dental morphology in the Xinjiang Uyghurs and correlation with the EDARV370A variant

Teeth are one of the most important materials for anthropological studies because they are likely to be preserved in ancient remains.While the frequencies of dental characteristics can provide clues to the phylogeny of populations,genetic studies at the individual level can further reveal the biological mechanisms and evolutionary context of dental characteristics.In this study,by analyzing 38 dental characteristics of 242 Xinjiang Uyghur individuals,we found that(i)the dental characteristics of the Uyghurs showed evidence of admixture between European and East Asian populations.The admixture proportions were in line with those previously reported in population genetic studies;(ii)the Xinjiang Uyghur dental characteristics formed three clusters in pairwise correlation analysis.One of the main clusters consisted of characteristics including incisor shoveling,double shoveling and mesial ridge;and(iii)all the characteristics in this cluster were significantly correlated with the genetic variant EDARV370A.The extracted composite phenotypic factor was also significantly associated with EDARV370A,which explained 18%of the total phenotypic variance.This indicated a pleiotropic effect,i.e.,the same genetic factor affects a number of dental characteristics at the same time.Our results confirmed that EDARV370A,a genetic variant that first originated in East Asia about 30000 years ago,played an important role in incisor shoveling in East Asia.This finding suggested that incisor shoveling in modern humans in East Asia is likely to have appeared after the late Pleistocene.     

Relative importance of long‐term changes in climate and land‐use on the phenology and abundance of legume crop specialist and generalist aphids

Abstract Insect populations are prone to respond to global changes through shifts in phenology, distribution and abundance. However, global changes cover several factors such as climate and land-use, the relative importance of these being largely unknown. Here, we aim at disentangling the effects of climate, land-use, and geographical drivers on aphid abundance and phenology in France, at a regional scale and over the last 40 years. We used aerial data obtained from suction traps between 1978 and 2015 on five aphid species varying in their degree of specialization to legumes, along with climate, legume crop area and geographical data. Effects of environmental and geographical variables on aphid annual abundance and spring migration dates were analyzed using generalized linear mixed models. We found that within the last four decades, aphids have advanced their spring migration by a month, mostly due to the increase in temperature early in the year, and their abundance decreased by half on average, presumably in response to a combination of factors. The influence of legume crop area decreased with the degree of specialization of the aphid species to such crops. The effect of geographical variation was high even when controlling for environmental variables, suggesting that many other spatially structured processes act on aphid population characteristics. Multifactorial analyses helped to partition the effects of different global change drivers. Climate and land-use changes have strong effects on aphid populations, with important implications for future agriculture. Additionally, trait-based response variation could have major consequences at the community scale.     

Identification of Quantitative Trait Loci for Grain Appearance and Milling Quality Using a Doubled-Haploid Rice Population

Improving grain quality, which is composed primarily of the appearance of the grain and its cooking and milling attributes, is a major objective of many rice-producing areas in China. In the present study, we conducted a marker-based genetic analysis of the appearance and milling quality of rice （Oryza sativa L.） grains using a doubled-haploid population derived from a cross between the indica inbred Zhenshan 97 strain and the japonica inbred Wuyujing 2 strain. Quantitative trait locus （QTL） analysis using a mixed linear model approach revealed that the traits investigated were affected by one to seven QTLs that individually explained 4.0%-30.7% of the phenotypic variation. Cumulatively, the QTL for each trait explained from 12.9% to 61.4% of the phenotypic variation. Some QTLs tended to have a pleiotropic or location-linked association as a cause of the observed phenotypic correlations between different traits. Improvement of the characteristics of grain appearance and grain weight, as well as an improvement in the milling quality of rice grains, would be expected by a recombination of different QTLs using marker-assisted selection.     

Genomic and mitochondrial evidence of ancient isolations and extreme introgression in the four-lined snake

Comparing mitochondrial and genomic phylogenies is an essential tool for investigating speciation processes,because each genome carries different inheritance properties and evolutionary characteristics.Furthermore,mitonuclear discordance may arise from ecological adaptation,historic isolation,population size changes,and sex-biased dispersal.Closely related taxa are expected to experience gene flow;however,this may not be true for insular populations or populations isolated in refugia.The four-lined snake Elaphe quatuorlineata has a fragmented distribution,separating populations of the Italian and Balkan Peninsulas,whereas several insular Aegean populations of significantly smaller body size(Cyclades island group and Skyros Island,Greece)are currently considered distinct subspecies.We constructed the species-tree phylogeny of this species utilizing genome-wide single nucleotide polymorphisms and a gene-tree based on complete cytochrome b sequences,aiming to detect convergence and discrepancies between biparentally and maternally inherited genomes.Population structuring,phylogenetic patterns and migration events among geographically defined lineages supported our hypothesis of isolation in multiple sub-refugia.Where biogeographical barriers did not restrict subsequent dispersal,extensive genetic exchange occurred between mainland Balkan populations.This process has led to the mitochondrial sweep of an ancestral mitolineage that survived only in peripheral(East Greece)and insular populations(North Cyclades and Skyros).The Central Cyclades represent an ancient lineage for both molecular markers that emerged almost 3.3 Mya.Considering their distinct morphology,insular E.quatuorlineata populations should be the future focus of an extensive sampling,especially since the mitonuclear discordance observed in this species could be related to ecological adaptations,such as the island-dwarfism phenomenon.     

Identification and characterization of short tandem repeats in the Tibetan macaque genome based on resequencing data

The Tibetan macaque, which is endemic to China,is currently listed as a Near Endangered primate species by the International Union for Conservation of Nature(IUCN)(2017). Short tandem repeats(STRs) refer to repetitive elements of genome sequence that range in length from 1–6 bp. They are found in many organisms and are widely applied in population genetic studies. To clarify the distribution characteristics of genome-wide STRs and understand their variation among Tibetan macaques,we conducted a genome-wide survey of STRs with next-generation sequencing of five macaque samples.A total of 1077 790 perfect STRs were mined from our assembly, with an N50 of 4 966 bp. Mono-nucleotide repeats were the most abundant, followed by tetraand di-nucleotide repeats. Analysis of GC content and repeats showed consistent results with other macaques. Furthermore, using STR analysis software(lob STR), we found that the proportion of base pair deletions in the STRs was greater than that of insertions in the five Tibetan macaque individuals(P0.05, t-test). We also found a greater number of homozygous STRs than heterozygous STRs(P0.05,t-test), with the Emei and Jianyang Tibetan macaques showing more heterozygous loci than Huangshan Tibetan macaques. The proportion of insertions and mean variation of alleles in the Emei and Jianyang individuals were slightly higher than those in the Huangshan individuals, thus revealing differences in STR allele size between the two populations.The polymorphic STR loci identified based on the reference genome showed good amplification efficiency and could be used to study population genetics in Tibetan macaques. The neighbor-joining tree classified the five macaques into two different branches according to their geographical origin,indicating high genetic differentiation between the Huangshan and Sichuan populations. We elucidated the distribution characteristics of STRs in the Tibetan macaque genome and provided an effective method for screening polymorphic STRs. Our results also lay a foundation for future genetic variation studies of macaques.     

Genetic Diversity： Geographical Distribution and Toxin Profiles of Microcystis Strains （Cyanobacteria） in China

Twenty strains of Microcystis Kütz were isolated from different freshwater bodies in China to analyze the diversity, geographical distribution and toxin profiles. Based on whole-cell polymerase chain reaction of cpcBA-IGS nucleotlde sequence, the derived neighbor-joining （NJ） and maximum parsimony （MP） trees Indicate that these strains of Microcystis can be divided into four clusters. The strains from south, middle and north region of China formed distinct lineages, suggesting high diversity and a geographical distribution from south to north locations. Moreover, the results being indicating high variable genotypes of the strains of the Microcystis strains from the same lake show that there Is high diversity of Microcystis within a water bloom population. Comparing the results of the present study with those reported for compared with 43 strains of Microcystis from other locations, also reveals Chinese strains have high similarity with those from regions in the North Hemispherical. This suggests that the Microcystis strains In the world might have a geographical distribution. Analysis of 30 strains using the primers MCF/TER and TOX2P/TOX2M showed that there was no correlation between the gene of cpcBA-IGS and the presence of racy. Toxic strains were founded to be predominant in different water bodies throughout China.     

Genetic Structure of the Red-spotted Tokay Gecko,Gekko gecko(Linnaeus, 1758)(Squamata: Gekkonidae) from Mainland Southeast Asia

This study was performed to explore the genetic diversity and genetic structure of red-spotted tokay geckos(Gekko gecko) from 23 different geographical areas in Thailand, Lao PDR and Cambodia. The mitochondrial tRNAGln/tRNA-Met/partial NADH dehydrogenase subunit 2 from 166 specimens was amplified and sequenced. A total of 54 different haplotypes were found. Highly significant genetic differences occurred between populations from different localities. The haplotype network revealed six major haplogroups(G1 to G6) belonging to different clades(clade A–E). Clade D and clade E were newly observed in this study. Haplogroup G4(clade D) was a sympatric population with haplogroup G1(clade B). The populations from northern Thailand were divided into two distinct haplogroups separated by mountain range. Genetic structure and genetic differentiation of the tokay in Southeast Asia was related to the geographical region sampled, spatial distance and natural barriers. Our results indicate that red-spotted tokay geckos from mainland Southeast Asia are cryptically diverse. Morphological comparisons, in addition to an intensive genetic investigation covering the whole species range, are needed to clarify the systematic and population structure of this species group.     

Genetic structure of Pallas’s squirrel (Callosciurus erythraeus) populations from artificial forests in Hongya County, Sichuan, China

To understand levels of population differentiation in Pallas’s squirrel (Callosciurus erythraeus) in fragmented habitats, we collected 83 samples from three patches of artificial forest in Hongya County, Sichuan Province, China. Sample numbers from each patch were as follows: 16 from Hanwang (HW), 27 from Muchansi (MCS) and 40 from Yanyandong (YYD). The mitochondrial DNA control region was sequenced and 18 haplotypes were observed. Our results showed that haplotype diversities of the three C. erythraeus populations were similar (0.771, 0.791 and 0.733). Fixation indices (F_st) of pairwise populations were between 0.21 and 0.31, and the estimated gene flow (Nm) was between 1 and 2. Analysis of molecular variance (AMOVA) showed that most molecular variation occurred within populations (74.82%); variances among populations were small but there was significant genetic differentiation. In addition, the neighbour-joining (NJ) tree showed three clades in the phylogenetic tree for population genetic structure. This was confirmed by the median-joining haplotype network. Furthermore, analysis of isolation by distance (IBD) showed that genetic differentiation among the three populations was positively related to geographical distance. However, tests of neutrality and the observed mismatch distribution of pairwise differences between sequences indicated that C. erythraeus populations were relatively stable in the past.     

Genetic structure of Pallas’s squirrel (Callosciurus erythraeus) populations from artificial forests in Hongya County, Sichuan, China

To understand levels of population differentiation in Pallas’s squirrel (Callosciurus erythraeus) in fragmented habitats, we collected 83 samples from three patches of artificial forest in Hongya County, Sichuan Province, China. Sample numbers from each patch were as follows: 16 from Hanwang (HW), 27 from Muchansi (MCS) and 40 from Yanyandong (YYD). The mitochondrial DNA control region was sequenced and 18 haplotypes were observed. Our results showed that haplotype diversities of the three C. erythraeus populations were similar (0.771, 0.791 and 0.733). Fixation indices (F_st) of pairwise populations were between 0.21 and 0.31, and the estimated gene flow (Nm) was between 1 and 2. Analysis of molecular variance (AMOVA) showed that most molecular variation occurred within populations (74.82%); variances among populations were small but there was significant genetic differentiation. In addition, the neighbour-joining (NJ) tree showed three clades in the phylogenetic tree for population genetic structure. This was confirmed by the median-joining haplotype network. Furthermore, analysis of isolation by distance (IBD) showed that genetic differentiation among the three populations was positively related to geographical distance. However, tests of neutrality and the observed mismatch distribution of pairwise differences between sequences indicated that C. erythraeus populations were relatively stable in the past.     

Microsatellite analysis of genetic diversity and population structure of Chinese mitten crab （Eriocheir sinensis）

Chinese mitten crab (Eriocheir sinensis) has higher commercial value as food source than any other species of Eriocheir in China.To evaluate the germplasm resources and characterize the genetic diversity and population structure of the crabs in different water systems,two stocks and two farming populations were assessed with 25 polymorphic microsallite loci available in public GenBank.Basic statistics showed that the average observed heterozygosity (Ho) amongst populations ranged from 0.5789 to 0.6824.However,a remarkable presence of inbreeding and heterozygote deficiencies were observed.To analyze population structure,pairwise FST coefficients explained only ～10.3% variability from the subdivision of mitten crab populations,the remaining variability stems from the subdivision within subpopulations.Although the four populations had slight differentiation,different allelic frequencies resulted in distinct population structures.Two stocks and one farming population were clustered together to the phylogenetic branch of Yangtze crab,with an approximate membership of 95%.Whereas,another fanning population was clustered singly to the phylogenetic branch of the Liaohe crab,with a membership of 97.1%.The tests for individual admixture showed that Yangtze crab had probably been contaminated with individuals from other water systems.Genetic relationships between populations also supported the conclusion that Yangtze crab and Liaohe crab had different gene pools in spite of the origins of the same species.     

Plastid Signals and the Bundle Sheath： Mesophyll Development in Reticulate Mutants

The development of a plant leaf is a meticulously orchestrated sequence of events producing a complex organ comprising diverse cell types. The reticulate class of leaf variegation mutants displays contrasting pigmentation between veins and interveinal regions due to specific aberrations in the development of mesophyll cells. Thus, the reticulate mutants offer a potent tool to investigate cell-type-specific developmental processes. The discovery that most mutants are affected in plastid-localized, metabolic pathways that are strongly expressed in vasculature-associated tis- sues implicates a crucial role for the bundle sheath and their chloroplasts in proper development of the mesophyll cells. Here, we review the reticulate mutants and their phenotypic characteristics, with a focus on those in Arabidopsis thali- ana. Two alternative models have been put forward to explain the relationship between plastid metabolism and meso- phyll cell development, which we call here the supply and the signaling hypotheses. We critically assess these proposed models and discuss their implications for leaf development and bundle sheath function in C3 species. The characteriza- tion of the reticulate mutants supports the significance of plastid retrograde signaling in cell development and highlights the significance of the bundle sheath in C3 photosynthesis.     

Proximity association in polygynous western black crested gibbons (Nomascus concolor jingdongensis): network structure and seasonality

We investigated the structure and seasonality of the proximity network in a group of polygynous western black crested gibbons (Nomascus concolor) using social network analysis. The spatial proximity changed seasonally and was affected by temperature and rainfall. Preferred proximity association was not distributed randomly among individuals. Kinship was one explanation for the social structure, as offspring preferred to maintain close proximity with their mothers. The proximity of infants to mothers decreased with age, and independent offspring had lower proximity to mothers than dependent ones. We found that the adult male had different proximity relationships with two different adult females. The frequency of proximity between the male and the infant-carrying female was significantly higher than that between the male and the female who had immigrated carrying one offspring of uncertain paternity into the group. Infanticide avoidance and/or predation protection for dependent infants might explain the proximity relationship differences. Temperature influenced group proximity association, with individual proximity increasing in the cold months and decreasing in the hot months. Group proximity decreased in months with higher anthropogenic disturbance.     

ISSR Analysis of the Genetic Diversity of the Endangered Species Sinopodophyllum hexandrum （Royle） Ying from Western Sichuan Province, China

Slnopodophyllum hexandrum （Royle） Ying Is an Important medicinal and endangered species. Inter-simple sequence repeats （ISSR） analysis was conducted on seven natural populations from western Slchuan Province to Investigate the genetic diversity of S. hexandrum. Leaf samples of 140 Individuals were collected. Of the 139 discernible fragments generated by 12 selected primers （among 100 primers）, 54 appeared to be polymorphlc. The percentage of polymorphlc bands （PPB） was 38.85% at the species level, and PPB within a population ranged from 7.91% to 23.74%. Low levels of genetic variation （He = 0.092, Ho = 0.142） and high levels of genetic differentiation among the populations （Gst= 62.25%） was detected on the basis of results from POPGENE and analysis of molecular variance （AMOVA）, respectively. Furthermore, the limited gene flow （Nm = 0.361） may result from biological characteristics, such as self-pollination and short distance seed dispersal. Based on the genetic and ecological Information available for S. hexandrum, we propose some appropriate strategies for the conservation of the endangered medicinal species in this region, namely rescuing and conserving the core populations for in situ conservation and sampling and preserving more populations with fewer Individuals from each population for ex situ conservation.     

Genetic polymorphism of mitochondrial DNA HVS-I and HVS-Ⅱ of Chinese Tu ethnic minority group

We analyzed the two hypervariable segments HVS-Ⅰ and HVS-Ⅱ of 108 Chinese Tu ethnic minority group samples for forensic and population genetics purposes.Comparing with Anderson sequence,79 polymorphic loci in HVS-Ⅰ and 40 in HVS-Ⅱ were found in Chi-nese Tu ethnic minority group mtDNA sequences,and 90 and 64 haplotypes were then defined.Haplotype diversity and the mean pair-wise differences were 0.9903±0.0013 and 5.7785 in HVS-Ⅰ,and 0.9777±0.0013 and 3.5819 in HVS-Ⅱ,respectively.By analyzing the hypervariable domain from nucleotide 1,6180 to 1,6193 in HVS-Ⅰ,we defined some new types of sequence variations.We also compared the relationship between Tu population and other populations using mtDNA HVS-Ⅰ sequences.According to Rst genetic distances,the phylogenetic tree showed that the Tu population,the Xi'an Han population,the Chinese Korean,and the Mongol ethnic group were in a clade.This indicated a close genetic relationship between them.There were far relations between the Tu population and other Chinese southern Han populations,Siberian,European,African,and other foreign populations.The results suggest that Tu population has a multi-origin and has also merged with other local populations.     

Genetic polymorphism of mitochondrial DNA HVS-I and HVS-Ⅱ of Chinese Tu ethnic minority group

We analyzed the two hypervariable segments HVS-Ⅰ and HVS-Ⅱ of 108 Chinese Tu ethnic minority group samples for forensic and population genetics purposes.Comparing with Anderson sequence,79 polymorphic loci in HVS-Ⅰ and 40 in HVS-Ⅱ were found in Chi-nese Tu ethnic minority group mtDNA sequences,and 90 and 64 haplotypes were then defined.Haplotype diversity and the mean pair-wise differences were 0.9903:±0.0013 and 5.7785 in HVS-Ⅰ,and 0.9777±0.0013 and 3.5819 in HVS-Ⅱ,respectively.By analyzing the hypervariable domain from nucleotide 1,6180 to 1,6193 in HVS-Ⅰ,we defined some new types of sequence variations.We also compared the relationship between Tu population and other populations using mtDNA HVS-Ⅰ sequences.According to Rst genetic distances,the phylogenetic tree showed that the Tu population,the Xi'an Han population,the Chinese Korean,and the Mongol ethnic group were in a clade.This indicated a close genetic relationship between them.There were far relations between the Tu population and other Chinese southern Han populations,Siberian,European,African,and other foreign populations.The results suggest that Tu population has a multi-origin and has also merged with other local populations.     

Association Between rs1344706 of ZNF804A and Schizophrenia:A Meta-analysis

Schizophrenia is one of the most serious mental diseases found in humans. Previous studies indicated that the single nucleotide polymorphism（SNP） rs1344706 in the gene ZNF804 A encoding zinc finger protein 804 A was associated with schizophrenia in Caucasian population but not in Chinese Han population. However, current results are conflicting in Asian population. In the present study, a meta-analysis was performed to revisit the association between rs1344706 and the risk of schizophrenia in Asian, Caucasian and other populations. Electronic search of Pub Med database identified 25 case–control studies with available genotype frequencies of rs1344706 for the meta-analysis,involving a total of 15,788 cases and 22,654 controls. A pooled odds ratio（OR） with 95% confidence interval（CI） was used to assess the association. The current meta-analysis showed an association between rs1344706 and schizophrenia in Caucasian populations（P = 0.028, OR = 1.138, 95% CI：1.014–1.278; P = 0.004 for heterogeneity） and Asian populations（P = 0.008, OR = 1.092, 95%CI： 1.023–1.165; P = 0.001 for heterogeneity）, but not in other populations（P = 0.286,OR = 1.209, 95% CI： 0.853–1.714, P = 0.120 for heterogeneity）. Egger’s test（P 〉 0.05） and Begg’s test（P 〉 0.05） are both suggestive of the lack of publication bias for the included studies. Thus, the absence of association in other populations suggests a genetic heterogeneity in the susceptibility of schizophrenia and demonstrates the difficulties in replicating genome-wide association study findings regarding schizophrenia across different ethnic populations. To validate the association between rs1344706 and schizophrenia, further studies with larger participant populations worldwide are needed.     

Genetic structure of Himalayan marmot (Marmota himalayana) population alongside the Qinghai–Tibet Railway

In order to verify the effect of social behavior and geographical isolation on the genetic structure of the Himalayan marmot (Marmota himalayana) population, we examined the genetic diversity of Himalayan marmots alongside the Qinghai–Tibet Railway using microsatellite markers. Eight microsatellite loci were used to examine 120 animals of 4 populations: Ulan (U), Delhi (D), Tuotuohe (T) and Ando (A). The results show that: (1) Himalayan marmots alongside the Qinghai–Tibet Railway are highly genetically diversified. The allele number (Na), effective allele number (Ne), observed heterozygosity (Ho), Nei’s expected heterozygosity (He) and polymorphism information content (PIC) of the total Himalayan marmot population were 4.75, 3.0332, 0.6990, 0.6672, 0.6102, respectively. (2) Himalayan marmots may be able to avoid inbreeding by a mechanism that will prevent the genetic diversity reduction caused by their social lifestyle. Heterozygote excess was observed at most loci. The inbreeding coefficients within the subpopulation (F_IS), in the total population (F_IT), the differentiation index of population (F_ST), and the gene flow (Nm) were ?0.2265, ?0.0477, 0.1458, and 1.4646, respectively. (3) The genetic differentiation of the Himalayan marmot population was in accordance with Wright’s “isolation by distance” theory. The Mantel test indicates that the correlation between genetic distance and geographic distance was significant (P < 0.05, r = 0.698). (4) Each of the four geographical populations had moderate differentiation. Both geographic distance and isolation could affect the population genetic structure of the Himalayan marmot. The maximum gene flow (3.5915), the smallest genetic differentiation index (0.0651), the lowest genetic distance (0.0700) and the highest genetic identity (0.9526) were all between the Ulan population and Delhi populations. (5) The cluster analysis, based on Nei’s standard genetic distance, showed that the populations of Delhi and Ulan were first merged in a cluster, and then Tuotuohe population was merged in the clustering. The Ando population was the last element in the clustering.     

Genetic structure of Himalayan marmot (Marmota himalayana) population alongside the Qinghai–Tibet Railway

In order to verify the effect of social behavior and geographical isolation on the genetic structure of the Himalayan marmot (Marmota himalayana) population, we examined the genetic diversity of Himalayan marmots alongside the Qinghai–Tibet Railway using microsatellite markers. Eight microsatellite loci were used to examine 120 animals of 4 populations: Ulan (U), Delhi (D), Tuotuohe (T) and Ando (A). The results show that: (1) Himalayan marmots alongside the Qinghai–Tibet Railway are highly genetically diversified. The allele number (Na), effective allele number (Ne), observed heterozygosity (Ho), Nei’s expected heterozygosity (He) and polymorphism information content (PIC) of the total Himalayan marmot population were 4.75, 3.0332, 0.6990, 0.6672, 0.6102, respectively. (2) Himalayan marmots may be able to avoid inbreeding by a mechanism that will prevent the genetic diversity reduction caused by their social lifestyle. Heterozygote excess was observed at most loci. The inbreeding coefficients within the subpopulation (F_IS), in the total population (F_IT), the differentiation index of population (F_ST), and the gene flow (Nm) were ?0.2265, ?0.0477, 0.1458, and 1.4646, respectively. (3) The genetic differentiation of the Himalayan marmot population was in accordance with Wright’s “isolation by distance” theory. The Mantel test indicates that the correlation between genetic distance and geographic distance was significant (P < 0.05, r = 0.698). (4) Each of the four geographical populations had moderate differentiation. Both geographic distance and isolation could affect the population genetic structure of the Himalayan marmot. The maximum gene flow (3.5915), the smallest genetic differentiation index (0.0651), the lowest genetic distance (0.0700) and the highest genetic identity (0.9526) were all between the Ulan population and Delhi populations. (5) The cluster analysis, based on Nei’s standard genetic distance, showed that the populations of Delhi and Ulan were first merged in a cluster, and then Tuotuohe population was merged in the clustering. The Ando population was the last element in the clustering.     

Forest characteristics and population structure of Glyptostrobus pensilis,a globally endangered relict species of southeastern China

The Chinese water pine Glyptostrobus pensilis is the sole surviving species of the genus Glyptostrobus. It is endemic to southern China, central Vietnam, and eastern Laos, and today it is nearly extinct in the wild. Forest community characteristics and population structure of G. pensilis in China have remained un-known up to now. We investigated six swamp forest stands and analyzed their forest community characteristics (i.e. vertical stratification, species composition, and diversity) and population structure, including the frequency distribution of DBH (diameter at breast height) and age-classes as found in Fujian Province, southeastern China. The vertical stratifications of all the forest stands were rather simple. The remaining wild specimens ranged from roughly 15 to some 357 years for an average of ca. 85 years, with only a few individuals less than 20 years old. Compared with the stands and populations of G. pensilis in Vietnam, the taxonomic compositions of the stands in the two regions were different, except for the dominant species-G. pensilis. The Shannon-Wiener index showed the overstory of each stand had much lower diversity (0.26 on average) in Fujian Province than that (1.97 on average) in Vietnam, whereas the diversity indices were about the same (around 2.41) for the understories in the two regions. Furthermore, we discovered 18 G. pensilis seedlings at the study sites in Fujian Province. This discovery demonstrates that G. pensilis regeneration is extremely poor and its populations are declining, although these populations are rela-tively healthier than those in Vietnam.