To explore genetic diversity and estimate the genetic differences among populations of Lutraria maxima in the coastal waters off south to southeast China,the morphology of the species of five different geographical po...To explore genetic diversity and estimate the genetic differences among populations of Lutraria maxima in the coastal waters off south to southeast China,the morphology of the species of five different geographical populations(Beihai,Weizhou Island,Zhanjiang,Xiamen,and Fuzhou)in Guangxi,Guangdong,and Fujian provinces was studied statistically in combination with the microsatellite markers.As revealed by morphological principal component analysis(PCA),the cumulative contribution rate of the first three principal components was 72.596%.The discrimination accuracy ranged from 47.5%to 80.0%,and the scatter plots of principal component and discriminant analysis were consistent in overall,showing that the Xiamen and Fuzhou populations were overlapped obviously.For microsatellite markers,10 pairs of polymorphic primers were obtained by high-throughput transcriptome sequencing,and used for genetic diversity analysis.It was showed that the average number of alleles and eff ective alleles observed in each population ranged from 8.100 to 10.900,and from 3.497 to 4.228,respectively.The average observed heterozygosity(H_(o))and expected heterozygosity(H_(e))in the five populations ranged from 0.541 to 0.615,and from 0.642 to 0.733,respectively.The genetic distance(DA)ranged from 0.078 to 0.523,and the population genetic differentiation index(F_(ST))ranged from 0.027 to 0.139.The unweighted pair-population method with arithmetic means(UPGMA)and structure analysis showed that the five populations could be divided into two main clusters,the Beibu Gulf group(Beihai and Weizhou Island)and the Southeast China Sea group(Zhanjiang,Xiamen,and Fuzhou),suggesting that L.maxima has been separated geographically by the barrier of the Leizhou Peninsula into two groups in evolution,which provided us with a scientific clue to better protect the bioresource and establish an appropriate fishery management stocks for L.maxima populations in south China.展开更多
Aphis glycines(Hemiptera: Aphididae) is considered as a cosmopolitan pest of cultivated soybean, major diffi culties in its control measures may be due to its higher genetic diversity; however, the knowledge about pop...Aphis glycines(Hemiptera: Aphididae) is considered as a cosmopolitan pest of cultivated soybean, major diffi culties in its control measures may be due to its higher genetic diversity; however, the knowledge about population genetic diversity of this species is limited. This study aimed to represent the genetic differentiation among different geographic populations of soybean aphid in Northeast China. In order to investigate and assess the genetic diversity, genetic differentiation, molecular variance, population structure, ecological importance and evolutionary history of A. glycines, we sequenced a fragment of one protein-coding gene, the cytochrome c oxidaseⅡof mitochondrial DNA gene. The results showed that four haplotypes were defi ned among COⅡ gene of 180 sequences of soybean aphid in Northeast China including H1 shared by all the populations. Lower haplotype diversity(Hd=0.3590±0.0420) and nucleotide diversity(Pi=0.0012±0.0002) were observed and high gene flow was detected in every two populations, while most of the variation(80.81%) arose from variability within A. glycines from individuals. Low genetic differentiation and high gene fl ow(Nm=2.106) indicated a high migration rate between the populations, which might reveal that gene flow in different geographic populations did not affect by geographical distance. The phylogenetic tree and the haplotype network of A. glycines were obtained based on sequences of COⅡ gene, there were no signifi cant genealogical branches or clusters recognized in NJ tree, and no clear distribution, delineation of haplotypes were demonstrated in the haplotype network according to geographical location. This study rejected the vicariance hypothesis: geographic isolation could be a barrier and it restricted A. glycines gene fl ow among 10 populations.展开更多
Knowledge of population genetic structure plays an important role in fisheries management.In this research,In-ter-Simple-Sequence-Repeat(ISSR)markers were employed to evaluate the genetic structure of Japanese sardine...Knowledge of population genetic structure plays an important role in fisheries management.In this research,In-ter-Simple-Sequence-Repeat(ISSR)markers were employed to evaluate the genetic structure of Japanese sardinella(Sardinella zun-asi)populations in the Northwest Pacific.Eighty seven individuals from 5 locations were screened using 4 highly polymorphic prim-ers.A total of 173 polymorphic loci were detected out of 191 loci amplified.Small but significant genetic differentiation was de-tected between the Chinese and Japanese populations by both AMOVA and pairwise FST analyses,which was further supported by cluster analysis.We consider that climate change during glaciations should be responsible for the genetic differentiation.Isolation by geographic distance among populations was observed,indicating that the distance might also lead to the genetic differentiation.However,no genetic structure was found within the populations off both the Chinese and Japanese coasts,indicating a high-level along-coast gene flow,which might result from ocean current transport and common ground for over-wintering.展开更多
Aims The two coexisting Leymus chinensis ecotypes exhibit remarkable divergences in adaptive strategies under drought and salinity in semi-humid meadows and semi-arid steppes.In order to detect the major genetic and e...Aims The two coexisting Leymus chinensis ecotypes exhibit remarkable divergences in adaptive strategies under drought and salinity in semi-humid meadows and semi-arid steppes.In order to detect the major genetic and environmental factors dominating the intraspecific phenotype variations and ecotype formation,the questions regarding the two distinct phenotypic forms(ecotypes)in L.chin-ensis were addressed:(i)did environments drive the L.chinensis ecotype formation?(ii)was there a molecular basis for the morphological divergence between the two ecotypes?(iii)which driving force dominated the intraspecies divergence,divergent natural selection,genetic drift or stabilizing selection?Methods We applied a series experiments on demographical,morphological and physiological traits of two Leymus chinensis ecotypes with gray green(GG)and yellow green(YG)leaf color in nine wild sites along a longitudinal gradient from 114°to 124°E in northeast China.The environmental data including mean annual precipitation,mean annual temperature,elevation and soil properties were collected.We compared the differences of morphological,physiological and genetic differentiations between the two ecotypes.Important FindingsThe GG type exhibited stronger fitness than YG type from the population densities,morphological traits(e.g.shoot height,leaf area,leaf and seed weights et al.),leaf mass per area(LMA)and physiological traits[relative water content(RWC),proline,soluble sugar contents].Most of above phenotypes(e.g.total shoot densities,spike length et al.)were significantly correlated with mean annual precipitation,mean annual temperature and soil water content(SWC),rarely a correlated with soil pH and soil nutrient.Transplanted populations showed convergence trend by their leaf chlorophyll contents and osmotic adjustments(proline and soluble sugar contents)in the greenhouse,but still exhibited their divergences between two ecotypes in the outdoor transplantation,suggesting that whether L.chinensis ecotype differentiated could be largely affected by the environmental conditions.Furthermore,by the comparison result of quantitative genetic variation(Q_(ST))values from phenotypes with theoretical neutral genetic differentiation(F_(ST)),differentiation in phenotypic traits greatly surpassed neutral predictions,implying that directional natural selection played a crucial role in L.chinen-sis ecotype differentiation.In addition,microsatellite analysis from Neighbor-joining tree and Bayesian assignment generated into two groups according to ecotypes,indicating molecular genetic differentiation also propelled the two ecotypes divergence.We conclude that L.chinensis population variations were driven by combing divergent natural selection(precipitation,temperature and SWCs)along the large-scale gradient and significantly intrinsic genetic differentiation.展开更多
Masu salmon,Oncorhynchus masou masou,is one of the most valuable fishery species that has been introduced to China,though to date no studies on the genetic diversity and genetic relationship among hatchery populations...Masu salmon,Oncorhynchus masou masou,is one of the most valuable fishery species that has been introduced to China,though to date no studies on the genetic diversity and genetic relationship among hatchery populations has been performed with molecular markers.We undertook such a study and sampled 120 individuals from three hatchery stocks and analyzed 20 microsatellite loci.All loci were polymorphic and a total of 91 alleles were detected.A relatively low level of genetic diversity was revealed with effective number of allele of 3.1094,3.3299 and 3.1894 and expected heterozygosity of 0.6600,0.6648 and 0.6638 in the three stocks,respectively.Deviations from Hardy-Weinberg equilibrium were found due to heterozygote deficit.Accordingly,evidence of genetic bottlenecks were found in the three stocks.An individual assignment test demonstrated that 85%of individuals were correctly assigned into their original stocks.Pairwise Fst revealed that significant differentiation occurred between these three stocks.The results of the study indicated that disequilibrium of genetic structure and differentiation has occurred in all three stocks.This information collectively provides a basis for measures to avoid of loss of genetic diversity and introgression in Chinese aquaculture.展开更多
Propylea japonica(Coleoptera:Coccinellidae)is a natural enemy insect with a wide range of predation in Chinese mainland and is commonly used in pest management.However,its genetic pattern(i.e.,genetic variation,geneti...Propylea japonica(Coleoptera:Coccinellidae)is a natural enemy insect with a wide range of predation in Chinese mainland and is commonly used in pest management.However,its genetic pattern(i.e.,genetic variation,genetic structure,and historical population dynamics)is still unclear,impeding the development of biological control of insect pests.Population genetic research has the potential to optimize strategies at different stages of the biological control processes.This study used 23 nuclear microsatellite sites and mitochondrial COI genes to investigate the population genetics of Propylea japonica based on 462 specimens collected from 30 sampling sites in China.The microsatellite dataset showed a moderate level of genetic diversity,but the mitochondrial genes showed a high level of genetic diversity.Populations from the Yellow River basin were more genetically diverse than those in the Yangtze River basin.Propylea japonica has not yet formed a significant genealogical structure in China,but there was a population structure signal to some extent,which may be caused by frequent gene flow between populations.The species has experienced population expansion after a bottleneck,potentially thanks to the tri-trophic plant–insect–natural enemy relationship.Knowledge of population genetics is of importance in using predators to control pests.Our study complements existing knowledge of an important natural predator in agroecosystems through estimating its genetic diversity and population differentiation and speculating about historical dynamics.展开更多
To investigate the genetic diversity of an edible fungus Pleurotus ferulae, a total of 89 wild samples collected from six geographical locations in the Xinjiang Uygur Autonomous Region of China and two geographical lo...To investigate the genetic diversity of an edible fungus Pleurotus ferulae, a total of 89 wild samples collected from six geographical locations in the Xinjiang Uygur Autonomous Region of China and two geographical locations in Italy, were analyzed using three DNA fragments including the translation elongation factor(EF1α), the second largest subunit of t he RNA polymerase II(RPB2) and the largest subunit of the RNA polymerase II(RPB1). The results indicated relatively abundant genetic variability in the wild resources of P. ferulae. The analysis of molecular variance(AMOVA) showed that the vast majority of the genetic variation was found within geographical populations. Both the Chinese populations and the Italian populations of P. ferulae displayed a limited genetic differentiation. The degree of differentiation between the Chinese populations and the Italian populations was obviously higher than that between the populations from the same region, and moreover the genetic differentiation among all the tested populations was correlated to the geographical distance. T he phylogeny analyses confirmed that samples from China and Italy belonged to another genetic group separated from Pleurotus eryngii. They were closely related to each other but were clustered according to their geographical origins, which implied the Chinese populations were highly differentiated from the Italian populations because of distance isolation, and the two populations from different regions might be still in the process of allopatric divergence.展开更多
Geographic isolation is a key factor in shaping the genetic structure of many fish species.Two sympatric species,Culter alburnus and C.mongolicus,are economically important fish that are widely distributed in China an...Geographic isolation is a key factor in shaping the genetic structure of many fish species.Two sympatric species,Culter alburnus and C.mongolicus,are economically important fish that are widely distributed in China and have been recently used as new aquaculture species.We used the mitochondrial DNA control region(CR)as a marker to investigate the genetic structure of the two species.Phylogenetic analysis revealed two major lineages(Lineages I and II)that were highly consistent with geographical patterns for C.alburnus and C.mongolicus.Based on genetic distance,the Zhujiang(Pearl)River Basin(ZRB)populations potentially represented a cryptic subspecies,which might be differentiated as the result of strict geographic isolation,an earlier diverged event,or peripheral areas.Genetic diversity analysis suggested that the Changjiang(Yangtze)River Basin(CRB)populations are located at,or near the core region of their origination,not only due to the larger population size at the CRB,but also their habitat diversity and suitability for its survival,and the genetic diversity dif ferences among basin populations were significant for the two species.Moreover,demographic analysis indicated that the two Culter species and most populations had undergone a period of population expansion during warm interglacial periods.However,the C.alburnus population of Huaihe River Basin(Weishan Lake)exhibited different patterns during the interglacial period,which may due to the latest diverged time of HRB and Weishan Lake located at the permafrost.Notably,the ZRB(in Songtao Reservoir)C.mongolicus population showed no genetic diversity and had a unique haplotype,which could be treated as a special gene pool for species conservation.In summary,geographic isolation is most likely responsible for the two Culter species distribution patterns.展开更多
Robinia pseudoacacia is an important afforesta-tion tree introduced to China in 1878.In the present study,we examined the genetic diversity among 687 strains rep-resenting four improved varieties and two secondary pro...Robinia pseudoacacia is an important afforesta-tion tree introduced to China in 1878.In the present study,we examined the genetic diversity among 687 strains rep-resenting four improved varieties and two secondary prov-enances,comprising 641 clones and 46 seedlings.Ninety-one simple sequence repeats(SSRs)were selected through segregation analysis and polymorphism characterization,and all sampled individuals were genotyped using well-characterized SSR markers.After excluding loci with non-neutral equilibrium,missing locus data and null alleles,we used 36 primer pairs to assess the genetic diversity of these germplasm resources,revealing vast genetic differentiation among the samples,with an average of 8.352 alleles per locus and a mean Shannon′s index of 1.302.At the popula-tion level,the partitioning of variability was assessed using analysis of molecular variance,which revealed 93%and 7%variation within and among collection sites,respectively.Four clusters were detected using structure analysis,indi-cating a degree of genetic differentiation among the six populations.Insights into the genetic diversity and structure of R.pseudoacacia provide a theoretical basis for the con-servation,breeding and sustainable development in China.展开更多
Pampus minor is an important commercial fish.Due to the similarity of external morphological characteristics among the genus Pampus species,P.minor has often been identified as the juvenile group of both P.cinereus an...Pampus minor is an important commercial fish.Due to the similarity of external morphological characteristics among the genus Pampus species,P.minor has often been identified as the juvenile group of both P.cinereus and P.argenteus.While little genetic background on this species is known,this study was based on control region sequences and provided the first evaluation of the genetic signature of 264 individuals of P.minor from 11 populations along the coasts of China and Malaysia.The results indicate high genetic haplotype diversity and low nucleotide diversity in this species.Additionally,two differentiated haplotype lineages were identified in the P.minor populations.However,phylogenetic structures corresponding to the geographical locations were unable to be established.Analysis of molecular variance identified a vast majority of the genetic variation occurring within populations.F-statistic test value(FST)of pairwise indicated that great differences existed between the Chinese and Malaysian P.minor populations.For the Chinese populations,the genetic differences were insignificant with the exception of the Xiamen population,which is a marginal population.During the late Pleistocene,a population expansion of P.minor occurred.These expanded populations originated from the glacial refugium in the South China Sea and then rapidly occupied and adapted to their new habitat.The results of this study provide genetic information for ensuring the protection and management of P.minor resources.展开更多
Objective:To explore genetic variations of Hypoderaeum conoideum collected from domestic ducks from 12 different localities in Thailand and Lao PDR,as well as their phylogenetic relationship with American and European...Objective:To explore genetic variations of Hypoderaeum conoideum collected from domestic ducks from 12 different localities in Thailand and Lao PDR,as well as their phylogenetic relationship with American and European isolates.Methods:The nucleotide sequences of their nuclear ribosomal DNA(ITS),mitochondrial cytochrome c oxidase subunit 1(CO1),and NADH dehydrogenase subunit 1(ND1)were used to analyze genetic diversity indices.Results:We found relatively high levels of nucleotide polymorphism in ND1(4.02%),whereas moderate and low levels were observed in CO1(2.11%)and ITS(0.96%),respectively.Based on these polymorphisms,the 20 ND1,12 CO1,and 18 ITS haplotypes were classified,and several common haplotypes were observed in all samples.At least three major lineages,namely American,European and Asian lineages,have been classified by phylogenetic analyses based on ND1 sequences.Conclusions:Our report demonstrates that the ND1 gene is the most suitable genetic marker to explore genetic variation and phylogenetic relationship of Hypoderaeum conoideum.However,a combination of all loci for ND1,CO1 and ITS would be of great value toward further genetic investigation of this endemic worldwide parasite.Thus,comprehensive molecular genetic analyses of Hypoderaeum conoideum from its worldwide distribution is needed to further understanding of the evolutionary and systematic relationships of this parasite.展开更多
The small yellow croaker(Larimichthys polyactis)belongs to the family Sciaenidae,which is an offshore warm fish species and widely distributed in the western Pacific.In this study,the variation of genetic diversity an...The small yellow croaker(Larimichthys polyactis)belongs to the family Sciaenidae,which is an offshore warm fish species and widely distributed in the western Pacific.In this study,the variation of genetic diversity and genetic differentiation among L.polyactis populations was analyzed by mitochondrial DNA control region.A total of 110 polymorphic sites were checked,which defined 134 haplotypes.High level of haplotype diversity(h=0.993±0.002)was detected in the examined range.Population genetic structure analyse(analysis of molecular variance,Fst)showed there were high gene flow among L.polyactis populations.The result showed that there were relatively high genetic diversity and low genetic differentiation among the Yellow Sea and the East China Sea populations,which can be attributed to diverse habitats,wide distribution range and high mutation rate of control region.Using phylogenetic methods,coalescent analyses(neutrality tests,mismatch distribution analysis,Bayesian skyline analyses)and molecular dating interpreted in conjunction with paleoclimatic and physiographic evidence,we inferred that the genetic make-up of extant populations of L.polyactis was shaped by Pleistocene environmental impacts on the historical demography of this species.Besides,relatively constant genetic diversity and larger effective population size were detected in recent L.polyactis population.The result showed that the fishing policy certainly,such as the summer closed fishing,played a role in protecting resources of L.polyactis.This study can offer a wealth of biological novelties which indicates genetic structure of L.polyactis population and provides the foundation for resources protection and policy setting.展开更多
Atlantic blue crabs(Callinectes sapidus)are ecologically and commercially fundamental.Life stages are punctuated with migration.Adults and juveniles live in estuaries and sounds.Larval stages develop in the coastal oc...Atlantic blue crabs(Callinectes sapidus)are ecologically and commercially fundamental.Life stages are punctuated with migration.Adults and juveniles live in estuaries and sounds.Larval stages develop in the coastal ocean.Juvenile and adult crabs occupy habitats from high salinities to fresh water.We determined whether maturing juvenile and adult blue crab habitat use is reflected in mitochondrial cytochrome oxidase 1 haplotypes.High salinity crabs had lower haplotype diversity(0.7260±.03900)compared to spawning crabs(0.9841±.00021)and low salinity crabs(0.94154±.00118).Significant pairwise differences in haplotypes were found between high salinity and spawning crabs(Nm=0.26018,p<0.001),and between high salinity and low salinity crabs(Nm=0.19482,p<0.001)indicating a lack of gene flow.Crabs from high salinity had highly significant genetic differentiation compared to spawning crabs(Fst=0.11830,p<0.001)and low salinity crabs(Fst=0.09689,p<0.001).Results support the hypothesis that genetics influence habitat selection.Crab larvae mix in the coastal ocean but occupy specific habitats upon return to sounds and estuaries.These findings have implications for the management of fisheries.展开更多
Aims Seagrasses provide a variety of ecosystem goods and services,but they are subjected to frequently anthropogenic disturbances.In this study,we genotyped samples collected from Zostera japonica mead-ows with dramat...Aims Seagrasses provide a variety of ecosystem goods and services,but they are subjected to frequently anthropogenic disturbances.In this study,we genotyped samples collected from Zostera japonica mead-ows with dramatic fluctuations in the area in order to understand the distribution of genetic variation within and among populations.Methods We collected samples from eight extant populations along coastal areas of southern China.Ten polymorphic microsatellites were adopted to genotype the samples.Parameters of genetic diversity and differentiation were calculated with general software.Important Findings High levels of genetic diversity were found in the studied populations,suggesting that the effective population size has not decreased signifi-cantly,which was supported by no signs of recent bottlenecks.High genetic diversity reflects an important role of sexual seedling recruit-ment in Z.japonica populations.We found a significant relationship between genetic differentiation and the shortest sea surface distance of populations,suggesting that ocean currents play a critical role in shap-ing the genetic structure of Z.japonica populations.STRUCTURE soft-ware analysis clustered the eight populations into two groups:western and eastern populations separated by the Qiongzhou Strait/Leizhou Peninsula,hinting that there was very limited gene flow through the narrow strait in this marine plant.Four populations had high contribu-tion diversity and,thus,high priority for in situ conservation.展开更多
The morphological similarities of Pampus fishes have led to considerable confusion in species-level identification,and no accurate information on neotype or DNA barcoding of Pampus echinogaster is available. Two hundr...The morphological similarities of Pampus fishes have led to considerable confusion in species-level identification,and no accurate information on neotype or DNA barcoding of Pampus echinogaster is available. Two hundred and seven specimens of P. echinogaster were collected from the coastal waters of Dandong, Dongying, Qingdao,Nantong, Zhoushan, Wenzhou, Changle, Taiwan, and Wakayama(Japan), from June 2010 to April 2013. The diagnostic characteristics of P. echinogaster are as follows: dorsal fin VIII-XI-43–51, anal fin V-VIII-43–49, pectoral fin 22–27, caudal fin 19–22, pelvic fin absent; first gill rakers sparse, slender(pointed), 3–4+12–16=15–20; vertebrae39–41; transverse occipital canal on top of head moderately small, wavy ridges not reaching upper origin of pectoral fin; ventral branch of lateral line canal spare, shorter than dorsal branch of lateral line canal. By combining congener sequences of the cytochrome oxidase I(COI) gene from Gen Bank, two absolute groups were detected among all specimens, which further indicated that two valid species were present based on genetic differences in amino acid sequences and the distance between the groups. The sequences of Group 1 can be regarded as DNA barcoding of P. echinogaster. The correct morphological redescription and DNA barcoding of P.echinogaster are presented here to provide a guarantee for efficient and accurate studies, a theoretical basis for classification, and enable appropriate fishery management and conservation strategies for the genus Pampus in the future.展开更多
Aurelia spp.ephyrae have been reported to form blooms in sea cucumber aquaculture ponds in the Bohai and Yellow Seas.To identify the species,we carried out a genetic analysis of Aurelia spp.ephyrae and medusae based o...Aurelia spp.ephyrae have been reported to form blooms in sea cucumber aquaculture ponds in the Bohai and Yellow Seas.To identify the species,we carried out a genetic analysis of Aurelia spp.ephyrae and medusae based on mitochondrial 16 S rRNA gene.Samples offour Aurelia sp.ephyrae populations were collected in sea cucumber aquaculture ponds and samples offour Aurelia sp.medusae populations were collected in coastal waters.Using a BLASTn search,we found that both the ephyrae collected in the aquaculture ponds and medusae collected in coastal waters belong to Aurelia coerulea.Seventeen haplotypes were recovered from the 16 S rRNA gene.The overall haplotype diversity and nucleotide diversity of the 166 A.coerulea individuals were 0.686%and 0.329%,respectively,indicating high haplotype diversity and low nucleotide diversity.Moreover,the haplotype diversity of ephyrae populations were generally lower than that of medusae populations with close sampling points.The genetic differentiation between ephyrae populations collected in the sea cucumber aquaculture ponds and A.coerulea medusae collected in coastal waters was not significant,suggesting the ephyrae populations in the sea cucumber culture ponds were part of the same genetic group as the medusae populations in the coastal waters.Phylogeographic analysis of the 16 S rRNA region revealed that there was no significant correlation between the haplotypes and the geographic distribution of populations.Pairwise fixation index values showed significant genetic differentiation and limited gene flow between A.coerulea population of Weifang and other locations.展开更多
Although the spatial genetic differentiation that occurs in animal populations has been extensively studied,information on temporal variations in genetic structure and diversity is still lacking,especially for animals...Although the spatial genetic differentiation that occurs in animal populations has been extensively studied,information on temporal variations in genetic structure and diversity is still lacking,especially for animals with oscillating populations.In the present study,we used the mtDNA D-loop sequence to assess the temporal genetic variation in samples from six successive years for the greater long-tailed hamster,Tscherskia triton.Sampling was carried out between 1998 and 2003 in cropland on the North China Plain,China.A total of 108 individuals were analyzed.The temporal samples showed a high level of genetic diversity.Substantial genetic changes in haplotype frequencies over time were detected for the hamster population.Random genetic drift and migration are likely to be the major factors responsible for the observed temporal pattern.The genetic diversity of the hamster population was higher in years with higher population density,and lower in years with lower population density.The result supports our hypothesis that genetic diversity decreases when population density declines in animals whose population oscillates greatly between years.The combined effects of inbreeding and genetic drift caused by reproduction,dispersal and population size might play important roles in the observed changes in genetic structure and diversity between years.展开更多
Wild progenitors are an excellent source for strengthening the genetic basis and accumulation of desirable variation lost because of directional selection and adaptation in modern cultivars.Here,we re-evaluate a landr...Wild progenitors are an excellent source for strengthening the genetic basis and accumulation of desirable variation lost because of directional selection and adaptation in modern cultivars.Here,we re-evaluate a landrace of Gossypium hirsutum,formerly known as Gossypium purpurascens.Our study seeks to understand the genomic structure,variation,and breeding potential of this landrace,providing potential insights into the biogeographic history and genomic changes likely associated with domestication.A core set of accessions,including current varieties,obsolete accessions,G.purpurascens,and other geographical landraces,are subjected to genotyping along with multilocation phenotyping.Population fixation statistics suggests a marked differentiation between G.purpurascens and three other groups,emphasizing the divergent genomic behavior of G.purpurascens.Phylogenetic analysis establishes the primitive nature of G.purpurascens,identifying it as a vital source of functional variation,the inclusion of which in the upland cotton(cultivated G.hirsutum)gene pool may broaden the genetic basis of modern cultivars.Genome-wide association results indicate multiple loci associated with domestication regions corresponding to flowering and fiber quality.Moreover,the conserved nature of G.purpurascens can also provide insights into the evolutionary process of G.hirsutum.展开更多
基金Supported by the Science and Technology Major Project of Guangxi Province(No.AA17204088)。
文摘To explore genetic diversity and estimate the genetic differences among populations of Lutraria maxima in the coastal waters off south to southeast China,the morphology of the species of five different geographical populations(Beihai,Weizhou Island,Zhanjiang,Xiamen,and Fuzhou)in Guangxi,Guangdong,and Fujian provinces was studied statistically in combination with the microsatellite markers.As revealed by morphological principal component analysis(PCA),the cumulative contribution rate of the first three principal components was 72.596%.The discrimination accuracy ranged from 47.5%to 80.0%,and the scatter plots of principal component and discriminant analysis were consistent in overall,showing that the Xiamen and Fuzhou populations were overlapped obviously.For microsatellite markers,10 pairs of polymorphic primers were obtained by high-throughput transcriptome sequencing,and used for genetic diversity analysis.It was showed that the average number of alleles and eff ective alleles observed in each population ranged from 8.100 to 10.900,and from 3.497 to 4.228,respectively.The average observed heterozygosity(H_(o))and expected heterozygosity(H_(e))in the five populations ranged from 0.541 to 0.615,and from 0.642 to 0.733,respectively.The genetic distance(DA)ranged from 0.078 to 0.523,and the population genetic differentiation index(F_(ST))ranged from 0.027 to 0.139.The unweighted pair-population method with arithmetic means(UPGMA)and structure analysis showed that the five populations could be divided into two main clusters,the Beibu Gulf group(Beihai and Weizhou Island)and the Southeast China Sea group(Zhanjiang,Xiamen,and Fuzhou),suggesting that L.maxima has been separated geographically by the barrier of the Leizhou Peninsula into two groups in evolution,which provided us with a scientific clue to better protect the bioresource and establish an appropriate fishery management stocks for L.maxima populations in south China.
基金Supported by the Special funds for Construction of Modern Agricultural Technology System(CARS-04)Public Welfare Industry(Agriculture)Special Fund(201103002)
文摘Aphis glycines(Hemiptera: Aphididae) is considered as a cosmopolitan pest of cultivated soybean, major diffi culties in its control measures may be due to its higher genetic diversity; however, the knowledge about population genetic diversity of this species is limited. This study aimed to represent the genetic differentiation among different geographic populations of soybean aphid in Northeast China. In order to investigate and assess the genetic diversity, genetic differentiation, molecular variance, population structure, ecological importance and evolutionary history of A. glycines, we sequenced a fragment of one protein-coding gene, the cytochrome c oxidaseⅡof mitochondrial DNA gene. The results showed that four haplotypes were defi ned among COⅡ gene of 180 sequences of soybean aphid in Northeast China including H1 shared by all the populations. Lower haplotype diversity(Hd=0.3590±0.0420) and nucleotide diversity(Pi=0.0012±0.0002) were observed and high gene flow was detected in every two populations, while most of the variation(80.81%) arose from variability within A. glycines from individuals. Low genetic differentiation and high gene fl ow(Nm=2.106) indicated a high migration rate between the populations, which might reveal that gene flow in different geographic populations did not affect by geographical distance. The phylogenetic tree and the haplotype network of A. glycines were obtained based on sequences of COⅡ gene, there were no signifi cant genealogical branches or clusters recognized in NJ tree, and no clear distribution, delineation of haplotypes were demonstrated in the haplotype network according to geographical location. This study rejected the vicariance hypothesis: geographic isolation could be a barrier and it restricted A. glycines gene fl ow among 10 populations.
基金supported by the Special Research Foundation for Public Welfare Marine Program (200905019-2)
文摘Knowledge of population genetic structure plays an important role in fisheries management.In this research,In-ter-Simple-Sequence-Repeat(ISSR)markers were employed to evaluate the genetic structure of Japanese sardinella(Sardinella zun-asi)populations in the Northwest Pacific.Eighty seven individuals from 5 locations were screened using 4 highly polymorphic prim-ers.A total of 173 polymorphic loci were detected out of 191 loci amplified.Small but significant genetic differentiation was de-tected between the Chinese and Japanese populations by both AMOVA and pairwise FST analyses,which was further supported by cluster analysis.We consider that climate change during glaciations should be responsible for the genetic differentiation.Isolation by geographic distance among populations was observed,indicating that the distance might also lead to the genetic differentiation.However,no genetic structure was found within the populations off both the Chinese and Japanese coasts,indicating a high-level along-coast gene flow,which might result from ocean current transport and common ground for over-wintering.
基金National Scientific Foundation of China(31470404 and 31070228).
文摘Aims The two coexisting Leymus chinensis ecotypes exhibit remarkable divergences in adaptive strategies under drought and salinity in semi-humid meadows and semi-arid steppes.In order to detect the major genetic and environmental factors dominating the intraspecific phenotype variations and ecotype formation,the questions regarding the two distinct phenotypic forms(ecotypes)in L.chin-ensis were addressed:(i)did environments drive the L.chinensis ecotype formation?(ii)was there a molecular basis for the morphological divergence between the two ecotypes?(iii)which driving force dominated the intraspecies divergence,divergent natural selection,genetic drift or stabilizing selection?Methods We applied a series experiments on demographical,morphological and physiological traits of two Leymus chinensis ecotypes with gray green(GG)and yellow green(YG)leaf color in nine wild sites along a longitudinal gradient from 114°to 124°E in northeast China.The environmental data including mean annual precipitation,mean annual temperature,elevation and soil properties were collected.We compared the differences of morphological,physiological and genetic differentiations between the two ecotypes.Important FindingsThe GG type exhibited stronger fitness than YG type from the population densities,morphological traits(e.g.shoot height,leaf area,leaf and seed weights et al.),leaf mass per area(LMA)and physiological traits[relative water content(RWC),proline,soluble sugar contents].Most of above phenotypes(e.g.total shoot densities,spike length et al.)were significantly correlated with mean annual precipitation,mean annual temperature and soil water content(SWC),rarely a correlated with soil pH and soil nutrient.Transplanted populations showed convergence trend by their leaf chlorophyll contents and osmotic adjustments(proline and soluble sugar contents)in the greenhouse,but still exhibited their divergences between two ecotypes in the outdoor transplantation,suggesting that whether L.chinensis ecotype differentiated could be largely affected by the environmental conditions.Furthermore,by the comparison result of quantitative genetic variation(Q_(ST))values from phenotypes with theoretical neutral genetic differentiation(F_(ST)),differentiation in phenotypic traits greatly surpassed neutral predictions,implying that directional natural selection played a crucial role in L.chinen-sis ecotype differentiation.In addition,microsatellite analysis from Neighbor-joining tree and Bayesian assignment generated into two groups according to ecotypes,indicating molecular genetic differentiation also propelled the two ecotypes divergence.We conclude that L.chinensis population variations were driven by combing divergent natural selection(precipitation,temperature and SWCs)along the large-scale gradient and significantly intrinsic genetic differentiation.
基金HRFRI Basic Science Research Special Funds(2009HSYZX-YY-10)Heilongjiang Natural Science Fund(C201044)Heilongjiang Postdoctoral Sustentation Fund(LRB10-081)。
文摘Masu salmon,Oncorhynchus masou masou,is one of the most valuable fishery species that has been introduced to China,though to date no studies on the genetic diversity and genetic relationship among hatchery populations has been performed with molecular markers.We undertook such a study and sampled 120 individuals from three hatchery stocks and analyzed 20 microsatellite loci.All loci were polymorphic and a total of 91 alleles were detected.A relatively low level of genetic diversity was revealed with effective number of allele of 3.1094,3.3299 and 3.1894 and expected heterozygosity of 0.6600,0.6648 and 0.6638 in the three stocks,respectively.Deviations from Hardy-Weinberg equilibrium were found due to heterozygote deficit.Accordingly,evidence of genetic bottlenecks were found in the three stocks.An individual assignment test demonstrated that 85%of individuals were correctly assigned into their original stocks.Pairwise Fst revealed that significant differentiation occurred between these three stocks.The results of the study indicated that disequilibrium of genetic structure and differentiation has occurred in all three stocks.This information collectively provides a basis for measures to avoid of loss of genetic diversity and introgression in Chinese aquaculture.
基金supported by a grant from the Key S&T Special Project of Henan,China(201300111500)the National Key R&D Program of China(2018YFD0200600)+1 种基金the Modern Agricultural System in Industry Technology of Henan Province,China(S2015-02-G05)the Key R&D and Promotion Project in Henan Province,China(212102110471).
文摘Propylea japonica(Coleoptera:Coccinellidae)is a natural enemy insect with a wide range of predation in Chinese mainland and is commonly used in pest management.However,its genetic pattern(i.e.,genetic variation,genetic structure,and historical population dynamics)is still unclear,impeding the development of biological control of insect pests.Population genetic research has the potential to optimize strategies at different stages of the biological control processes.This study used 23 nuclear microsatellite sites and mitochondrial COI genes to investigate the population genetics of Propylea japonica based on 462 specimens collected from 30 sampling sites in China.The microsatellite dataset showed a moderate level of genetic diversity,but the mitochondrial genes showed a high level of genetic diversity.Populations from the Yellow River basin were more genetically diverse than those in the Yangtze River basin.Propylea japonica has not yet formed a significant genealogical structure in China,but there was a population structure signal to some extent,which may be caused by frequent gene flow between populations.The species has experienced population expansion after a bottleneck,potentially thanks to the tri-trophic plant–insect–natural enemy relationship.Knowledge of population genetics is of importance in using predators to control pests.Our study complements existing knowledge of an important natural predator in agroecosystems through estimating its genetic diversity and population differentiation and speculating about historical dynamics.
基金funded by the National Basic Research Program of China (2014CB138305)the China Agriculture Research System (CARS24)
文摘To investigate the genetic diversity of an edible fungus Pleurotus ferulae, a total of 89 wild samples collected from six geographical locations in the Xinjiang Uygur Autonomous Region of China and two geographical locations in Italy, were analyzed using three DNA fragments including the translation elongation factor(EF1α), the second largest subunit of t he RNA polymerase II(RPB2) and the largest subunit of the RNA polymerase II(RPB1). The results indicated relatively abundant genetic variability in the wild resources of P. ferulae. The analysis of molecular variance(AMOVA) showed that the vast majority of the genetic variation was found within geographical populations. Both the Chinese populations and the Italian populations of P. ferulae displayed a limited genetic differentiation. The degree of differentiation between the Chinese populations and the Italian populations was obviously higher than that between the populations from the same region, and moreover the genetic differentiation among all the tested populations was correlated to the geographical distance. T he phylogeny analyses confirmed that samples from China and Italy belonged to another genetic group separated from Pleurotus eryngii. They were closely related to each other but were clustered according to their geographical origins, which implied the Chinese populations were highly differentiated from the Italian populations because of distance isolation, and the two populations from different regions might be still in the process of allopatric divergence.
基金Supported by the National Key Technology Research and Development Program(No.2015BAD25B01)the Earmarked Fund for China Agriculture Research system(No.CARS-45)
文摘Geographic isolation is a key factor in shaping the genetic structure of many fish species.Two sympatric species,Culter alburnus and C.mongolicus,are economically important fish that are widely distributed in China and have been recently used as new aquaculture species.We used the mitochondrial DNA control region(CR)as a marker to investigate the genetic structure of the two species.Phylogenetic analysis revealed two major lineages(Lineages I and II)that were highly consistent with geographical patterns for C.alburnus and C.mongolicus.Based on genetic distance,the Zhujiang(Pearl)River Basin(ZRB)populations potentially represented a cryptic subspecies,which might be differentiated as the result of strict geographic isolation,an earlier diverged event,or peripheral areas.Genetic diversity analysis suggested that the Changjiang(Yangtze)River Basin(CRB)populations are located at,or near the core region of their origination,not only due to the larger population size at the CRB,but also their habitat diversity and suitability for its survival,and the genetic diversity dif ferences among basin populations were significant for the two species.Moreover,demographic analysis indicated that the two Culter species and most populations had undergone a period of population expansion during warm interglacial periods.However,the C.alburnus population of Huaihe River Basin(Weishan Lake)exhibited different patterns during the interglacial period,which may due to the latest diverged time of HRB and Weishan Lake located at the permafrost.Notably,the ZRB(in Songtao Reservoir)C.mongolicus population showed no genetic diversity and had a unique haplotype,which could be treated as a special gene pool for species conservation.In summary,geographic isolation is most likely responsible for the two Culter species distribution patterns.
基金This work was supported by the Doctoral Scientific Research Starting Foundation of Henan University of Science and Technology(13480089)National Nature Science Foundation of China(31570677)+1 种基金the National Key R&D Program of China(2017YFD0600503)the National Forestry and Grassland Administration of Science and Technology Development Center Project(2016007).
文摘Robinia pseudoacacia is an important afforesta-tion tree introduced to China in 1878.In the present study,we examined the genetic diversity among 687 strains rep-resenting four improved varieties and two secondary prov-enances,comprising 641 clones and 46 seedlings.Ninety-one simple sequence repeats(SSRs)were selected through segregation analysis and polymorphism characterization,and all sampled individuals were genotyped using well-characterized SSR markers.After excluding loci with non-neutral equilibrium,missing locus data and null alleles,we used 36 primer pairs to assess the genetic diversity of these germplasm resources,revealing vast genetic differentiation among the samples,with an average of 8.352 alleles per locus and a mean Shannon′s index of 1.302.At the popula-tion level,the partitioning of variability was assessed using analysis of molecular variance,which revealed 93%and 7%variation within and among collection sites,respectively.Four clusters were detected using structure analysis,indi-cating a degree of genetic differentiation among the six populations.Insights into the genetic diversity and structure of R.pseudoacacia provide a theoretical basis for the con-servation,breeding and sustainable development in China.
基金The National Key Research and Development Program of China under contract No.2018YFC1406302the National Programme on Global Change and Air-Sea Interaction under contract No.GASI-02-SCS-YDsum+1 种基金the Fond of Fujian Provincial Research Institutes of Basic Research and Public Service Special Operations under contract No.2017R1006-5the Fond of Bilateral Cooperation of Maritime Affairs under contract No.2200207。
文摘Pampus minor is an important commercial fish.Due to the similarity of external morphological characteristics among the genus Pampus species,P.minor has often been identified as the juvenile group of both P.cinereus and P.argenteus.While little genetic background on this species is known,this study was based on control region sequences and provided the first evaluation of the genetic signature of 264 individuals of P.minor from 11 populations along the coasts of China and Malaysia.The results indicate high genetic haplotype diversity and low nucleotide diversity in this species.Additionally,two differentiated haplotype lineages were identified in the P.minor populations.However,phylogenetic structures corresponding to the geographical locations were unable to be established.Analysis of molecular variance identified a vast majority of the genetic variation occurring within populations.F-statistic test value(FST)of pairwise indicated that great differences existed between the Chinese and Malaysian P.minor populations.For the Chinese populations,the genetic differences were insignificant with the exception of the Xiamen population,which is a marginal population.During the late Pleistocene,a population expansion of P.minor occurred.These expanded populations originated from the glacial refugium in the South China Sea and then rapidly occupied and adapted to their new habitat.The results of this study provide genetic information for ensuring the protection and management of P.minor resources.
基金supported by Faculty of Medicine,Thammasat University,Thailand to CT,grant number 2-18/2562
文摘Objective:To explore genetic variations of Hypoderaeum conoideum collected from domestic ducks from 12 different localities in Thailand and Lao PDR,as well as their phylogenetic relationship with American and European isolates.Methods:The nucleotide sequences of their nuclear ribosomal DNA(ITS),mitochondrial cytochrome c oxidase subunit 1(CO1),and NADH dehydrogenase subunit 1(ND1)were used to analyze genetic diversity indices.Results:We found relatively high levels of nucleotide polymorphism in ND1(4.02%),whereas moderate and low levels were observed in CO1(2.11%)and ITS(0.96%),respectively.Based on these polymorphisms,the 20 ND1,12 CO1,and 18 ITS haplotypes were classified,and several common haplotypes were observed in all samples.At least three major lineages,namely American,European and Asian lineages,have been classified by phylogenetic analyses based on ND1 sequences.Conclusions:Our report demonstrates that the ND1 gene is the most suitable genetic marker to explore genetic variation and phylogenetic relationship of Hypoderaeum conoideum.However,a combination of all loci for ND1,CO1 and ITS would be of great value toward further genetic investigation of this endemic worldwide parasite.Thus,comprehensive molecular genetic analyses of Hypoderaeum conoideum from its worldwide distribution is needed to further understanding of the evolutionary and systematic relationships of this parasite.
基金The National Key Research and Development Program of China under contract No.2018YFD0900905。
文摘The small yellow croaker(Larimichthys polyactis)belongs to the family Sciaenidae,which is an offshore warm fish species and widely distributed in the western Pacific.In this study,the variation of genetic diversity and genetic differentiation among L.polyactis populations was analyzed by mitochondrial DNA control region.A total of 110 polymorphic sites were checked,which defined 134 haplotypes.High level of haplotype diversity(h=0.993±0.002)was detected in the examined range.Population genetic structure analyse(analysis of molecular variance,Fst)showed there were high gene flow among L.polyactis populations.The result showed that there were relatively high genetic diversity and low genetic differentiation among the Yellow Sea and the East China Sea populations,which can be attributed to diverse habitats,wide distribution range and high mutation rate of control region.Using phylogenetic methods,coalescent analyses(neutrality tests,mismatch distribution analysis,Bayesian skyline analyses)and molecular dating interpreted in conjunction with paleoclimatic and physiographic evidence,we inferred that the genetic make-up of extant populations of L.polyactis was shaped by Pleistocene environmental impacts on the historical demography of this species.Besides,relatively constant genetic diversity and larger effective population size were detected in recent L.polyactis population.The result showed that the fishing policy certainly,such as the summer closed fishing,played a role in protecting resources of L.polyactis.This study can offer a wealth of biological novelties which indicates genetic structure of L.polyactis population and provides the foundation for resources protection and policy setting.
文摘Atlantic blue crabs(Callinectes sapidus)are ecologically and commercially fundamental.Life stages are punctuated with migration.Adults and juveniles live in estuaries and sounds.Larval stages develop in the coastal ocean.Juvenile and adult crabs occupy habitats from high salinities to fresh water.We determined whether maturing juvenile and adult blue crab habitat use is reflected in mitochondrial cytochrome oxidase 1 haplotypes.High salinity crabs had lower haplotype diversity(0.7260±.03900)compared to spawning crabs(0.9841±.00021)and low salinity crabs(0.94154±.00118).Significant pairwise differences in haplotypes were found between high salinity and spawning crabs(Nm=0.26018,p<0.001),and between high salinity and low salinity crabs(Nm=0.19482,p<0.001)indicating a lack of gene flow.Crabs from high salinity had highly significant genetic differentiation compared to spawning crabs(Fst=0.11830,p<0.001)and low salinity crabs(Fst=0.09689,p<0.001).Results support the hypothesis that genetics influence habitat selection.Crab larvae mix in the coastal ocean but occupy specific habitats upon return to sounds and estuaries.These findings have implications for the management of fisheries.
基金The National Key Basic Research Special Foundation of China(2014FY130300).
文摘Aims Seagrasses provide a variety of ecosystem goods and services,but they are subjected to frequently anthropogenic disturbances.In this study,we genotyped samples collected from Zostera japonica mead-ows with dramatic fluctuations in the area in order to understand the distribution of genetic variation within and among populations.Methods We collected samples from eight extant populations along coastal areas of southern China.Ten polymorphic microsatellites were adopted to genotype the samples.Parameters of genetic diversity and differentiation were calculated with general software.Important Findings High levels of genetic diversity were found in the studied populations,suggesting that the effective population size has not decreased signifi-cantly,which was supported by no signs of recent bottlenecks.High genetic diversity reflects an important role of sexual seedling recruit-ment in Z.japonica populations.We found a significant relationship between genetic differentiation and the shortest sea surface distance of populations,suggesting that ocean currents play a critical role in shap-ing the genetic structure of Z.japonica populations.STRUCTURE soft-ware analysis clustered the eight populations into two groups:western and eastern populations separated by the Qiongzhou Strait/Leizhou Peninsula,hinting that there was very limited gene flow through the narrow strait in this marine plant.Four populations had high contribu-tion diversity and,thus,high priority for in situ conservation.
基金The National Natural Science Foundation of China under contract No.41776171the National Programme on Global Change and Air-Sea Interaction under contract Nos GASI-02-SCS-YSWspr/aut and GASI-02-PAC-YDsum/aut+1 种基金the Scientific Research Foundation of TIO,SOA under contract No.2016010the Bilateral Cooperation of Maritime Affairs under contract No.2200207
文摘The morphological similarities of Pampus fishes have led to considerable confusion in species-level identification,and no accurate information on neotype or DNA barcoding of Pampus echinogaster is available. Two hundred and seven specimens of P. echinogaster were collected from the coastal waters of Dandong, Dongying, Qingdao,Nantong, Zhoushan, Wenzhou, Changle, Taiwan, and Wakayama(Japan), from June 2010 to April 2013. The diagnostic characteristics of P. echinogaster are as follows: dorsal fin VIII-XI-43–51, anal fin V-VIII-43–49, pectoral fin 22–27, caudal fin 19–22, pelvic fin absent; first gill rakers sparse, slender(pointed), 3–4+12–16=15–20; vertebrae39–41; transverse occipital canal on top of head moderately small, wavy ridges not reaching upper origin of pectoral fin; ventral branch of lateral line canal spare, shorter than dorsal branch of lateral line canal. By combining congener sequences of the cytochrome oxidase I(COI) gene from Gen Bank, two absolute groups were detected among all specimens, which further indicated that two valid species were present based on genetic differences in amino acid sequences and the distance between the groups. The sequences of Group 1 can be regarded as DNA barcoding of P. echinogaster. The correct morphological redescription and DNA barcoding of P.echinogaster are presented here to provide a guarantee for efficient and accurate studies, a theoretical basis for classification, and enable appropriate fishery management and conservation strategies for the genus Pampus in the future.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23050301)the Special Exchange Program from the Chinese Academy of Sciences,the National Natural Science Foundation of China(Nos.41576152,41876138)+1 种基金the Instrument Developing Project of the Chinese Academy of Sciences(No.YJKYYQ20180047)the Key Research and Development Program of Yantai(No.2018ZHGY073)。
文摘Aurelia spp.ephyrae have been reported to form blooms in sea cucumber aquaculture ponds in the Bohai and Yellow Seas.To identify the species,we carried out a genetic analysis of Aurelia spp.ephyrae and medusae based on mitochondrial 16 S rRNA gene.Samples offour Aurelia sp.ephyrae populations were collected in sea cucumber aquaculture ponds and samples offour Aurelia sp.medusae populations were collected in coastal waters.Using a BLASTn search,we found that both the ephyrae collected in the aquaculture ponds and medusae collected in coastal waters belong to Aurelia coerulea.Seventeen haplotypes were recovered from the 16 S rRNA gene.The overall haplotype diversity and nucleotide diversity of the 166 A.coerulea individuals were 0.686%and 0.329%,respectively,indicating high haplotype diversity and low nucleotide diversity.Moreover,the haplotype diversity of ephyrae populations were generally lower than that of medusae populations with close sampling points.The genetic differentiation between ephyrae populations collected in the sea cucumber aquaculture ponds and A.coerulea medusae collected in coastal waters was not significant,suggesting the ephyrae populations in the sea cucumber culture ponds were part of the same genetic group as the medusae populations in the coastal waters.Phylogeographic analysis of the 16 S rRNA region revealed that there was no significant correlation between the haplotypes and the geographic distribution of populations.Pairwise fixation index values showed significant genetic differentiation and limited gene flow between A.coerulea population of Weifang and other locations.
文摘Although the spatial genetic differentiation that occurs in animal populations has been extensively studied,information on temporal variations in genetic structure and diversity is still lacking,especially for animals with oscillating populations.In the present study,we used the mtDNA D-loop sequence to assess the temporal genetic variation in samples from six successive years for the greater long-tailed hamster,Tscherskia triton.Sampling was carried out between 1998 and 2003 in cropland on the North China Plain,China.A total of 108 individuals were analyzed.The temporal samples showed a high level of genetic diversity.Substantial genetic changes in haplotype frequencies over time were detected for the hamster population.Random genetic drift and migration are likely to be the major factors responsible for the observed temporal pattern.The genetic diversity of the hamster population was higher in years with higher population density,and lower in years with lower population density.The result supports our hypothesis that genetic diversity decreases when population density declines in animals whose population oscillates greatly between years.The combined effects of inbreeding and genetic drift caused by reproduction,dispersal and population size might play important roles in the observed changes in genetic structure and diversity between years.
基金supported by funding from the National Key Technology R&D Program,the Ministry of Science and Technology(2016YFD0100203,2017FD0101601)the crop germplasm conservation program of the ministry of Agriculture(2015NWB039)。
文摘Wild progenitors are an excellent source for strengthening the genetic basis and accumulation of desirable variation lost because of directional selection and adaptation in modern cultivars.Here,we re-evaluate a landrace of Gossypium hirsutum,formerly known as Gossypium purpurascens.Our study seeks to understand the genomic structure,variation,and breeding potential of this landrace,providing potential insights into the biogeographic history and genomic changes likely associated with domestication.A core set of accessions,including current varieties,obsolete accessions,G.purpurascens,and other geographical landraces,are subjected to genotyping along with multilocation phenotyping.Population fixation statistics suggests a marked differentiation between G.purpurascens and three other groups,emphasizing the divergent genomic behavior of G.purpurascens.Phylogenetic analysis establishes the primitive nature of G.purpurascens,identifying it as a vital source of functional variation,the inclusion of which in the upland cotton(cultivated G.hirsutum)gene pool may broaden the genetic basis of modern cultivars.Genome-wide association results indicate multiple loci associated with domestication regions corresponding to flowering and fiber quality.Moreover,the conserved nature of G.purpurascens can also provide insights into the evolutionary process of G.hirsutum.
