Niches of plant populations in mangrove reserve of Qi’ao Island, Pearl River Estuary

Thirty-two 10 × 10 m² quadrats were set up in four mangrove communities for the study of the niches of nine plants with horizontal and vertical resource sequences in Dawei Bay, Qi’ao Island, Zhuhai City. Generally, species diversities of natural mangroves were higher than those of plantations. The diversities decreased along sequence of substrate layer, shrub layer and tree layer in natural mangroves; and were highest on the shrub layer in plantations. At the horizontal resource sequence, the niche breadth varied 0.132–0.896 (B_(sw)) and 0.120–0.693 (B_(L)). The niche breadth of Acanthus ilicifolius and Aegiceras corniculatum were the highest and that of Spartina alterniflora was the lowest. At the vertical resource sequence, the niche breadth varied 0–0.400 (B_(sw)) and 0.333–0.747 (B_(L)). All the niche breadth values were the lowest except those of A. ilicifolius and A. corniculatum. The niche similarity of the populations varied 0–0.746 and 0–1.000 at the horizontal and vertical resource sequences, respectively. A. ilicifolius and A. corniculatum had niche overlap with all plants at the horizontal resource sequence, while the introduced Sonneratia caseolaris and Sonneratiaapetala had no such overlapping between six and five plants in the community, respectively. At the vertical resource sequence, A. ilicifolius and A. corniculatum had niche overlapping with all the populations. The more niche overlapping existed among the other populations. The results indicated that, currently, the mangrove plantation in Qi’ao Island had a simplex structure and composition of species. The status of plant populations’ niche was determined by the species selected and structure of afforestation. It is suggested to create forest gaps artificially and introduce Kandelia obovata saplings to reverse its current status of lower niche breadth, facilitate natural regeneration and spreading of A. corniculatum and A. ilicifolius, and accelerate the restoration process of natural mangrove. Simultaneously, the species matching and planting methods of mix stands should be emphasized in the future.     

Niches of plant populations in mangrove reserve of Qi’ao Island, Pearl River Estuary

Thirty-two 10 × 10 m² quadrats were set up in four mangrove communities for the study of the niches of nine plants with horizontal and vertical resource sequences in Dawei Bay, Qi’ao Island, Zhuhai City. Generally, species diversities of natural mangroves were higher than those of plantations. The diversities decreased along sequence of substrate layer, shrub layer and tree layer in natural mangroves; and were highest on the shrub layer in plantations. At the horizontal resource sequence, the niche breadth varied 0.132–0.896 (B_(sw)) and 0.120–0.693 (B_(L)). The niche breadth of Acanthus ilicifolius and Aegiceras corniculatum were the highest and that of Spartina alterniflora was the lowest. At the vertical resource sequence, the niche breadth varied 0–0.400 (B_(sw)) and 0.333–0.747 (B_(L)). All the niche breadth values were the lowest except those of A. ilicifolius and A. corniculatum. The niche similarity of the populations varied 0–0.746 and 0–1.000 at the horizontal and vertical resource sequences, respectively. A. ilicifolius and A. corniculatum had niche overlap with all plants at the horizontal resource sequence, while the introduced Sonneratia caseolaris and Sonneratiaapetala had no such overlapping between six and five plants in the community, respectively. At the vertical resource sequence, A. ilicifolius and A. corniculatum had niche overlapping with all the populations. The more niche overlapping existed among the other populations. The results indicated that, currently, the mangrove plantation in Qi’ao Island had a simplex structure and composition of species. The status of plant populations’ niche was determined by the species selected and structure of afforestation. It is suggested to create forest gaps artificially and introduce Kandelia obovata saplings to reverse its current status of lower niche breadth, facilitate natural regeneration and spreading of A. corniculatum and A. ilicifolius, and accelerate the restoration process of natural mangrove. Simultaneously, the species matching and planting methods of mix stands should be emphasized in the future.     

Loss of Genetic Diversity of Domesticated Panax notoginseng F H Chen as Evidenced by ITS Sequence and AFLP Polymorphism： A Comparative Study with P. stipuleanatus H T Tsai et K M Feng

In the present study, we evaluated the genetic diversity of Panax notoginseng F H Chen, a domesticated species, and P. stipuleanatus H T Tsai et K M Feng, an endangered wild species in southeastern Yunnan and adjacent areas in Vietnam, using sequences of the internal transcribed spacer (ITS) regions of nuclear ribosomal DNA and amplified fragment length polymorphism (AFLP) markers. Twenty-four accessions from three plantations of P. notoginseng and 51 samples from eight populations of P. stipuleanatus were assayed. A total of 694 bp of partial sequences of 18S, ITS 1, 5.8S, ITS2, and partial sequences of 26S were obtained. No sequence variation was detected within P. notoginseng and nine sites (1.30%) were variable in P. stipuleanatus. Two-thirds of the variable sites were found between Langqiao and other populations. In P. notoginseng, four pairs of AFLP primer combinations generated 312 bands, of which 240 (76.9%) were polymorphic and 60.15% of the polymorphisms were harbored within plantations. Approximately 41.0% and 66.9% of bands were polymorphic in population D7 and 5589, respectively. In P.stipuleanatus, the same four primer combinations produced 346 bands, of which 334 (96.5%) were polymorphic and approximately 62.14% of polymorphisms were maintained within populations. Considerable variations were observed. The percentage of polymorphic bands ranged from 50.2% to 84.9% and the average over populations was 70.9%. Cluster analysis did not show correlation of genetic differentiation with the distinctive leaf morphology of P. stipuleanatus (i.e. one form with bipinnatifid leaflets and the other with undivided leaflets). Because over 40% of genetic variations were maintained among populations and because of the very restricted distribution of P. stipuleanatus, all natural populations of this species should be conserved in situ. Considering that there are variations in P. notoginseng within and among plantations, we suggest establishing a genetic resource conservation garden or reintroducing P. notoginseng into its native habitats in southwestern China. Such reintroduction should be carefully executed after large-scale screening of genetic variation within the species.     

Latitudinal changes in species diversity of permafrost wetland plant communities in Great Xing’an Mountain valleys of Northeast China

Studying the changes of species diversity in plant communities along latitude gradients is important to discover the correlation between biodiversity and environmental factors. Along the main ridges of the Great Xing’an Mountains, 12 natural permafrost wetlands in the valleys were investigated from north to south. Latitudinal changes in species diversity were analyzed with regressive analysis. About 150 plant species were recorded and were found to be in the 12 permafrost wetland plant communities. Most plants belong to the Compositae or Gramineae. The number of family, genus and species increased significantly in the herb layer with decreasing latitude (P < 0.01), but decreased significantly in the shrub layer (P < 0.01). Species composition and the orders of dominant species in the plant communities by importance value changed along latitude. Latitudinal changes of α-diversity in permafrost wetland plant communities were different in the herb and shrub layers. With decreasing latitude, species richness and species diversity increased in the herb layer; but decreased in the shrub layer. The opposite patterns were found for species dominance. Species evenness in the shrub layer decreased with decreasing latitude. ?-diversity in the herb and shrub layers decreased first, and then increased, and finally decreased with increasing latitude. Species composition in the herb layer was similar among the plots at higher latitudes.     

Latitudinal changes in species diversity of permafrost wetland plant communities in Great Xing’an Mountain valleys of Northeast China

Studying the changes of species diversity in plant communities along latitude gradients is important to discover the correlation between biodiversity and environmental factors. Along the main ridges of the Great Xing’an Mountains, 12 natural permafrost wetlands in the valleys were investigated from north to south. Latitudinal changes in species diversity were analyzed with regressive analysis. About 150 plant species were recorded and were found to be in the 12 permafrost wetland plant communities. Most plants belong to the Compositae or Gramineae. The number of family, genus and species increased significantly in the herb layer with decreasing latitude (P < 0.01), but decreased significantly in the shrub layer (P < 0.01). Species composition and the orders of dominant species in the plant communities by importance value changed along latitude. Latitudinal changes of α-diversity in permafrost wetland plant communities were different in the herb and shrub layers. With decreasing latitude, species richness and species diversity increased in the herb layer; but decreased in the shrub layer. The opposite patterns were found for species dominance. Species evenness in the shrub layer decreased with decreasing latitude. ?-diversity in the herb and shrub layers decreased first, and then increased, and finally decreased with increasing latitude. Species composition in the herb layer was similar among the plots at higher latitudes.     

Distribution and interspecific correlation of root biomass density in an arid Elaeagnus angustifolia–Achnatherum splendens community

Main objective of this study was to determine the interspecific relationships between two dominant species in terms of root distribution in a typical arid tree-herbage (Elaeagnus angustifolia–Achnatherum splendens) community at Xidatan, Pingluo County, Ningxia Autonomous Region, Northwest China. Eight concentric zones (namely, Z1–Z8) were set from the bases of E. angustifolia individuals to the open lands and five soil profiles were excavated in each zone. Each soil profile was divided into five layers at the depths of 0–10 cm, 10–30 cm, 30–60 cm, 60–100 cm and 100–150 cm. Roots were collected for each species, and soil water content (SWC) and soil bulk density (SBD) were measured for each layer. We found noteworthy roots layer separation in the sub-canopy zones (Z1–Z4). The soil layers with highest fine root biomass density (FRBD) of A. splendens was primarily in the 0–10 cm, which were significantly shallower than those of E. angustifolia; whereas in the inter-canopy zones (Z5–Z8), inconsistent separation, or even overlapping of highest-FRBD-layers emerged between the two dominant species. Correlation analyses showed that negative correlations of FRBD between the two species mainly occurred in those soil layers with relatively higher FRBD and lower SWC. In contrast, positive correlations corresponded with relatively lower FRBD and higher SWC.     

Distribution and interspecific correlation of root biomass density in an arid Elaeagnus angustifolia–Achnatherum splendens community

Main objective of this study was to determine the interspecific relationships between two dominant species in terms of root distribution in a typical arid tree-herbage (Elaeagnus angustifolia–Achnatherum splendens) community at Xidatan, Pingluo County, Ningxia Autonomous Region, Northwest China. Eight concentric zones (namely, Z1–Z8) were set from the bases of E. angustifolia individuals to the open lands and five soil profiles were excavated in each zone. Each soil profile was divided into five layers at the depths of 0–10 cm, 10–30 cm, 30–60 cm, 60–100 cm and 100–150 cm. Roots were collected for each species, and soil water content (SWC) and soil bulk density (SBD) were measured for each layer. We found noteworthy roots layer separation in the sub-canopy zones (Z1–Z4). The soil layers with highest fine root biomass density (FRBD) of A. splendens was primarily in the 0–10 cm, which were significantly shallower than those of E. angustifolia; whereas in the inter-canopy zones (Z5–Z8), inconsistent separation, or even overlapping of highest-FRBD-layers emerged between the two dominant species. Correlation analyses showed that negative correlations of FRBD between the two species mainly occurred in those soil layers with relatively higher FRBD and lower SWC. In contrast, positive correlations corresponded with relatively lower FRBD and higher SWC.     

Physical characteristics of Chinese Hakka

Using standard and internationally validated methods,86 anthropologic characteristics were determined in 650 male(305 from urban areas and 345 from rural areas) and 704 female(331 from urban areas,373 from rural areas) Chinese Hakka adults living in Guangdong and Jiangxi.The data were used to calculate 24 anthropologic indices,which were analyzed statistically.The physical characteristics of Hakka subjects were analyzed and compared with reference ethnic data.There were four main findings of this study.First,a small proportion of Hakka adults had an eye fold on the upper eyelid,but a large proportion had a mongoloid fold.The eye slits were narrow in most adults,had a medium nasal root height and straight bridges,and most of the external angles were prominent.The nasal base was upturned in most men.The distributions of the three types of nasal base in women were similar.The proportions of subjects with middle and high alae nasi heights were high and similar.Males with a maximum nostril diameter were mostly classified as transverse and oblique,while many women were classified as transverse and had relatively wide alae nasi.The round lobe type was the most common.Upper lip skin height was mostly classified as medium.Lips were classified as thin.The hair was black,eyes were brown,and the skin was yellowish.Second,the head length was long in male Hakka.The minimum frontal breadth,face breadth,lip height,and interocular breadth were similar to those of North-Asian populations.Meanwhile,head breadth,morphological facial height,nose breadth,mouth breadth,and nose height were similar to those of South-Asian populations.Head length was long in female Hakka.The minimum frontal breadth,face breadth,lip height,and interocular breadth were similar to those of North-Asian populations.Head breadth,nose breadth,and mouth breadth were similar to those of South-Asian populations.Third,the stature of male and female Hakka in urban and rural areas was classified as medium.The proportions of male and female Hakka classified as mesocephaly(length-breadth index of the head),hypsicephalic type,metriocephalic type(breadth-height index of the head) mesorrhiny,long trunk,subbrachyskelic type,broad shoulder breadth,and narrow distance between iliac crests were higher than those of other types.Finally,principal component analyses showed that the physical characteristics of Hakka were between those of South-Asian and North-Asian ethnic populations,but were generally closer to those of North-Asian populations in China.     

Carbon storage and potentials of the broad-leaved forest in alpine region of the Qinghai-Xizang Plateau,China北大核心CSCD

Aims Our objective was to explore the vegetation carbon storages and their variations in the broad-leaved forests in the alpine region of the Qinghai-Xizang Plateau that includes Qinghai Province and Xizang Autonomous Region. Methods Based on forest resource inventory data and field sampling, this paper studied the carbon storage, its sequestration rate, and the potentials in the broad-leaved forests in the alpine region of the Qinghai-Xizang Plateau. Important findings The vegetation carbon storage in the broad-leaved forest accounted for 310.70 Tg in 2011, with the highest value in the broad-leaved mixed forest and the lowest in Populus forest among the six broad-leaved forests that include Quercus, Betula, Populus, other hard broad-leaved species, other soft broad-leaved species, and the broadleaved mixed forest. The carbon density of the broad-leaved forest was 89.04 Mg•hm2, with the highest value in other hard broad-leaved species forest and the lowest in other soft broad-leaved species forest. The carbon storage and carbon density in different layers of the forests followed a sequence of overstory layer > understory layer > litter layer > grass layer > dead wood layer, which all increased with forest age. In addition, the carbon storage of broad-leaved forest increased from 304.26 Tg in 2001 to 310.70 Tg in 2011. The mean annual carbon sequestration and its rate were 0.64 Tg•a1 and 0.19 Mg•hm2•a1, respectively. The maximum and minimum of the carbon sequestration rate were respectively found in other soft broad-leaved species forest and other hard broad-leaved species forest, with the highest value in the mature forest and the lowest in the young forest. Moreover, the carbon sequestration potential in the tree layer of broad-leaved forest reached 19.09 Mg•hm2 in 2011, with the highest value found in Quercus forest and the lowest in Betula forest. The carbon storage increased gradually during three inventory periods, indicating that the broad-leaved forest was well protected to maintain a healthy growth by the forest protection project of Qinghai Province and Xizang Autonomous Region.     

The failed invasion of Harmonia axyridis in the Azores,Portugal: Climatic restriction or wrong population origin?

We tested two questions:(i)whether the climatic conditions of the Azorean Islands in Portugal may have restricted the invasion of Harmonia axyridis across this archipelago and(ii)determine what population of this species could have a higher probability of invading the islands.We used MaxEnt to project the climate requirements of different H.axyridis populations from three regions of the world,and the potential global niche of the species in the Azorean islands.Then we assessed the suitability of the islands for each of the three H.axyridis populations and global potential niche through histograms analysis,Principal Component Analysis(PCA)of climate variables,and a variable-by-variable assessment of the suitability response curves compared with the climatic conditions of the Azores.Climatic conditions of the Azores are less suitable for the U.S.and native Asian populations of H.axyridis,and more suitable for European populations and the global potential niche.The PCA showed that the climatic conditions of the islands differed from the climatic requirements of H.axyridis.This difference is mainly explained by precipitation of the wettest month,isothermality,and the minimum temperature of the coldest month.We concluded that the climatic conditions of the Azores could have influenced the establishment and spread of H.axyridis on these islands from Europe.Our results showed that abiotic resistance represented by the climate of the potentially colonizable zones could hinder the establishment of invasive insects,but it could vary depending of the origin of the colonizing population.     

Patterns of ramet population of Iris japonica Thunb. and their effects on herb diversity in different microsites on Jinyun Mountain, China

Spatial patterns of ramet population of Iris japonica Thunb. and their effect on species diversity in the herb layer of 3 microsites (open area of forest edge (OAFE), bamboo forest (BF) and evergreen broad-leaved forest (EBF)) on Jinyun Mountain were studied using spatial pattern, niche and diversity analyses in a combination of population and community methods. The results were as follows: (1) judged by V/m and Morisita index (Iδ), ramet population of I. japonica in 3 microsites all clumped from scale 0.5 m × 0.5 m to 2 m × 2 m; (2) the pattern scale and pattern intensity both gradually decreased on all scales, and the density of ramet population of I. japonica decreased with the increase in canopy density and the decrease in relative photon flux density (RPFD) and R/FR from OAFE to EBF. In OAFE and BF, widespread I. japonica had significantly negative influence on the dominance of original dominant species and on species diversity in the herb layer (p < 0.05), while those influences in EBF were extremely weak. The mechanisms that pattern characteristics of ramet population of I. japonica influence herb diversity in 3 microsites were different. In OAFE, strong regeneration niche (above-ground spatial and below-ground root) and trophic niche (nutrient) competition had significantly negative influence on the species diversity of rare herbs and dwarf herbs. In BF, strong regeneration niche (below-ground root) and trophic niche (above-ground for light and below-ground for nutrient) competition had negative effect on the occurrence of rare species and on the survival of other herb species. In EBF, weak niche competition had little effect on the survival of herb species. Intensity of regeneration niche and trophic niche competition between I. japonica and other herb species is the determinant to the mechanism that ramet population of I. japonica influences herb diversity.     

Global,regional, and cladistic patterns of variation in climatic niche breadths in terrestrial elapid snakes

We obtai ned geo-refere need occurre nee and climatic data from in dividual localities for 59 species of terrestrial elapid snakes, used phylogenetic generalized least squares regression to investigate spatial and cladistic patter ns of variation in climatic niche breadths, and compared patter ns within and across regions and clades to see if they parallel or differ from each other. Specifically, we test (1) whether a species' climatic niche breadth on a given niche axis relates to its position along that axis, and to its climatic niche breadth on another niche axis, and (2) whether variation in niche breadths among species is explained by within-locality variation in climatic conditions or by among-locality variation. We found that:(1) there is an overall global patter n, and patter ns in individual regi ons or clades gen erally parallel each other and global patter ns;(2) species in wanner environments have narrower temperature niche breadths (TNBs);(3) precipitation niche breadth (PNB) and position are positively related;⑷ TNB and PNB are not related;and ⑸ within-locality variation in climatic conditions explains most variation in TNBs, whereas among-locality variation explains most variation in PNBs. Our results are consistent with those reported for lizards of the families Phrynosomatidae and Varanidae, con firm the importance of withi n-locality n iche breadth to species n iche breadth, and show a more im porta nt role of amon g-locality n iche breadth in affecting species niche breadth in terrestrial elapids than in lizards.     

Changes of a forest bird community in Hong Kong of China in 10 years

The changes in the bird community structure of the largest natural secondary forest of Hong Kong over 10 years were investigated. Densities of the 10 most abundant species in 1993–1995 and 2003–2005 were compared using t-test. All resident habitat generalists showed significant decline in densities. Two forest specialists showed significant increase in densities: one is native and the other is exotic species. The trend of changes in the forest bird community of Hong Kong is mainly related to the absence of nearby forests that could act as “source” of forest dependent species to colonize the local secondary forests, and the invasion of exotic species.     

Changes of a forest bird community in Hong Kong of China in 10 years

The changes in the bird community structure of the largest natural secondary forest of Hong Kong over 10 years were investigated. Densities of the 10 most abundant species in 1993–1995 and 2003–2005 were compared using t-test. All resident habitat generalists showed significant decline in densities. Two forest specialists showed significant increase in densities: one is native and the other is exotic species. The trend of changes in the forest bird community of Hong Kong is mainly related to the absence of nearby forests that could act as “source” of forest dependent species to colonize the local secondary forests, and the invasion of exotic species.     

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.     

Cloning and Sequence Analysis of Genome from the Inner Mongolia Strain of the Endogenous Betaretroviruses （enJSRV）

In order to amplify the complete genome of enJSRV from the strain of Inner Mongolia （enJSRV-NM）, we used enJSRV-specific and JSRV-specific DNA probes in dot blot hybridization. Seven pairs of primers were designed based on Genbank sequences. Seven fragments were obtained by PCR and were cloned into the PMD19-T vectors. The recombinant plasmids were sequenced and analyzed. The results showed that the genome was 7 942 bp in length and contained four overlapping open reading frames corresponding to the gag, pro, pol and env genes as well as an additional open reading frame （orf-x） that overlaps the 3＇ end of the pol gene. The nucleotide acid sequences of the enJSRV-NM loci were compared with the sequences of South Africa enJS56A1 strain （Accession No.AF153615） and USA JSRV21 strain （Accession No. AF105220）. The nucleotide acid identities were 99.2% and 92.3% respectively. Two zinc fingers were found in the NC region in the predicted amino acid sequence. However, the YXXM motif, which is a reliable molecular marker for the infectious exogenous virus, was not found in the TM region. It was found that the enJSRV-NM region was 90%-98% identical at the amino acid level to its exogenous infectious counterparts in most of the retroviral genome. This is the first nucleotide sequence of enJSRV reported in P.R China. The resource work has provided a wide range of information useful not only for expression genomics and annotation of genomic DNA sequence, but also for further research on the clinical diagnosis of OPA.     

Diet composition of the lizard P odarcis lilfordi (Lacertidae) on 2 small islands: an individualresource network approach

Despite it is widely accepted that intrapopulation variation is fundamental to ecological and evolutionary processes,this level of information has only recently been included into network analysis of species/population interactions.When done,it has revealed non-random patterns in the distribution of trophic resources.Nestedness in resource use among individuals is the most recurrent observed pattern,often accompanied by an absence of modularity,but no previous studies examine bipartite modularity.We use network analysis to describe the diet composition of the Balearic endemic lizard Podarcis lilfordi in 2 islets at population and individual levels,based on the occurrence of food items in fecal samples.Our objectives are to 1)compare niche structure at both levels,2)characterize niche partition using nestedness and modularity,and 3)assess how size,sex,season,and spatial location influence niche structure.At population-level niche width was wide,but narrow at the level of the individual.Both islet networks were nested,indicating similar ranking of the food preferences among individuals,but also modular,which was partially explained by seasonality.Sex and body size did not notably affect diet composition.Large niche overlap and therefore possibly relaxed competition were observed among females in one of the islets and during spring on both islets.Likewise,higher modularity in autumn suggests that higher competition could lead to specialization in both populations,because resources are usually scarce in this season.The absence of spatial location influence on niche might respond to fine-grained spatio-temporally distribution of food resources.Behavioral traits,not included in this study,could also influence resource partitioning.     

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.     

Neither Biased Sex Ratio nor Spatial Segregation of the Sexes in the Subtropical Dioecious Tree Eurycorymbus cavaleriei （Sapindaceae）

Knowledge of sex ratio and spatial distribution of males and females of dioecious species is both of evolutionary interest and of crucial importance for biological conservation. Eurycorymbus cavaleriei, the only species in the genus Eurycorymbus （Sapindaceae）, is a dioecious tree endemic to subtropical montane forest in South China. Sex ratios were investigated in 15 natural populations for the two defined ages （young and old）. Spatial distribution of males and females was further studied in six large populations occurring in different habitats （fragmented and continuous）. The study revealed a slight trend of male- biased sex ratio in both ages of E. cavaleriei, but sex ratio of most populations （13 out of 15） did not display statistically significant deviation from equality. All of the four significantly male-biased populations in the young class shifted to equality or even female-biased, The Ripley＇s K analysis of the distribution of males with respect to females suggested that individuals of the opposite sexes were more randomly distributed rather than spatially structured. These results suggest that the male-biased sex ratio in E. cavaleriei may result from the precocity of males and habitat heterogeneity. The sex ratio and the sex spatial distribution pattern are unlikely to constitute a serious threat to the survival of the species.