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1.
L. W. Mengistu G. W. Mueller-Warrant R. E. Barker 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,101(1-2):70-79
The genetic diversity of Poa annua L.populations collected from western Oregon grass-seed fields was surveyed using 18 randomly amplified polymorphic DNA (RAPD) markers. Markers from 1357 individual plants from 47 populations collected at three sampling dates (fall, winter, and
spring) for 16 sites were used to measure genetic diversity within and among populations. Site histories varied from low to
high herbicide selection pressure, and some sites were subdivided by 3 years of differing post-harvest residue management.
Gene diversity statistics, simple frequency of haplotype occurrence, and analysis of molecular variance (AMOVA) revealed the
presence of significant variability in P. annua among sites, among collection dates within sites, and within collection dates. Nei gene-diversity statistics and population-differentiation
parameters indicated that P. annua populations were highly diverse. Mean Nei gene diversity (h) for all 47 populations was 0.241 and total diversity (HT) was 0.245. A greater proportion of this diversity, however, was within (HS=0.209) rather than among (GST=0.146) populations. When populations were grouped by season of collection, within-group diversity was HS=0.241, while among-group diversity was GST=0.017. When populations were grouped by site, within-group diversity was HS=0.224, while among-group diversity was GST=0.087. The diversity among populations within season for fall, winter, and spring collections was GST=0.121, 0.142, and 0.133, respectively. Populations collected from fields with histories of high herbicide selection pressure
showed low differentiation among collection dates, with GST as low as 0.016, whereas those collected from fields with low herbicide selection pressure showed greater differentiation
among collection dates, with GST as high as 0.125. At high selection-pressure sites, populations were also lower in gene diversity (as low as h=0.155), while
at low selection-pressure sites there was higher gene diversity (as high as h=0.286). The site to site variability was greater
for the high selection-pressure sites (GST=0.107 or 69% of the total among-population variance), while the season of germination variability was greater at sites of
low herbicide-selection pressure (GST=0.067, or 70% of the total among-population variance). High initial diversity coupled with a long-term re-supply of genotypes
from the seed bank must have been factors in maintaining the genetic diversity of this weed despite the intensive use of herbicides.
Knowledge of the genetic diversity of Willamette Valley P. annua should help in formulating more effective strategies for managing this weed.
Received: 24 July 1999 / 11 November 1999 相似文献
2.
Hiroyuki Akiyama 《American journal of botany》1994,81(10):1280-1287
Enzyme electrophoresis was used to estimate genetic variability within and among populations of five species of the genus Leucodon (L. atrovirens, L. luteus, L. nipponicus, L. sapporensis, and L. temperatus). All of these perennial, dioecious plants are epiphytic on tree trunks and produce numerous spores that are released in winter. Gene diversity within populations (HS) was low (0.070) in L. nipponicus, which grows in disturbed habitats, and high (0.169–0.202) in the other four species, which inhabit stable environments. Gene diversity between populations relative to total diversity (GST) was low in L. temperatus (0.042) and L. luteus (0.043), suggesting that extensive gene flow occurs among populations. GST was moderate in L. sapporensis (0.104) and L. atrovirens (0.114); these values are still less than those previously reported for terrestrial mosses. Since epiphytes could disperse their spores effectively by the wind, low genetic divergence among populations may be related to the epiphytic habit of the species. On the other hand, high GST value (0.208) was found in L. nipponicus. It is probably explained by the genetic differentiation of populations by genetic drift, for the species forms geographically and ecologically isolated populations with small number of individuals. We also observed incongruity between morphological and genetic similarity among species. 相似文献
3.
MYONG GI CHUNG 《Plant Species Biology》1994,9(3):177-182
Abstract Genetic diversity of Korean populations in Hosta clausa was investigated using starch gel electrophoresis. Hosta clausa is widespread, grows only along streamsides, and has both sexual and asexual reproduction. Populations of the species are small and isolated. Thirty-two percent of the loci examined were polymorphic, and mean genetic diversity within populations (Hep=0.082) was lower than mean estimates for species with very similar life history characteristics (0.131), particularly for its congener H. yingeri (0.250). The mean number of multilocus genotypes per population was 8.7, and genotypic diversity index (DG) was 0.84. Significant differences in allele frequencies among populations were found in all seven polymorphic loci (P < 0.001). About one-fifth of the total allozyme variation was among populations (GST=0.192). Indirect estimate of the number of migrants per generation (Nm=0.48, calculated from mean GST) and nine private alleles found indicate that gene movement among populations was low. The low levels of genetic diversity within populations and the relatively high levels of genetic diversity among populations suggest that strong moist habitat preferences, clonal reproduction, low level of gene flow among populations, genetic drift, and historical events may have played roles in the genetic structuring of the species. 相似文献
4.
Camssonia guadalupensis ssp. clementina (Onagraceae) and Cryptantha traskiae (Boraginaceae) share many species characteristics that affect levels and pattern of genetic variation. In addition, they have a similar distribution, are found in the same habitat, and share ecological history by virtue of co-occurring at nearly all of the locations at which they are found. All populations of the two taxa on San Clemente Island were surveyed for genotypes at 16 allozyme loci, revealing generally low levels of genetic variation. However, Cam. g. clementina has more genetic variation than Cryp. traskiae at the taxon level (P = 37.5 versus 18.8, A = 1.69 versus 1.31, and HE = 0.088 versus 0.003) and significantly more alleles and higher heterozygosity within populations (A = 1.09 versus 1.03, AE = 1.02 versus 1.00; HO = 0.013 versus 0.001 and HE = 0.017 versus 0.003). Some populations of each taxon are monomorphic at all loci. Much greater differentiation among populations occurs in Cam. g. clementina (GST = 0.810) than in Cryp. traskiae (GST = 0.042). Locations of the more variable populations of each taxon do not coincide, and the pattern of genetic similarity of localities differs in the two taxa. Striking population genetic differences exist between these taxa despite shared species characteristics, distribution, habitat, and recent history. 相似文献
5.
Alnus hirsuta in Korea was measured to estimate the amount and pattern of genetic diversity and population structure. The mean genetic
diversity within populations was 0.166. Korean alder populations have slightly high levels of genetic diversity compared to
those of two Canadian alder species. The genetic differentiation among populations accounted for 9% of the total variation.
The rate of gene flow was estimated high (Nm=2.63). Analysis of inbreeding coefficient, calculated for all polymorphic loci in each population, showed a substantial heterozygote
deficiency relative to Hardy-Weinberg expectations. The mean G
ST
value of A. hirsuta in Korea was 0.087. The low value of G
ST
in this species, reflecting little spatial genetic differentiation, may indicate extensive gene flow. A relationship between
the mean heterozygosity and annual rainfall showed a positive relationship (r
2=0.54, F=4.67).
Received 8 August 1998/ Accepted in revised form 7 July 1999 相似文献
6.
Genetic diversity and differentiation within and among nine G. morsitans morsitans populations from East and southern Africa was assessed by examining variation at seven microsatellite loci and a mitochondrial
locus, cytochrome oxidase (COI). Mean COI diversity within populations was 0.63 ± 0.33 and 0.81 taken over all populations. Diversities averaged over microsatellite
loci were high (mean number of alleles/locus ≥7.4; mean H
E ≥ 65%) in all populations. Diversities averaged across populations were greater in East Africa (mean number of alleles = 22 ± 2.6;
mean h
e = 0.773 ± 0.033) than in southern Africa (mean number of alleles = 18.7 ± 4.0; mean h
e = 0.713 ± 0.072). Differentiation among all populations was highly significant (R
ST = 0.25, F
ST = 0.132). Nei’s G
ij
statistics were 0.09 and 0.19 within regions for microsatellites and mitochondria, respectively; between regions, G
ij
was 0.14 for microsatellites and 0.23 for mitochondria. G
ST among populations was 0.23 for microsatellite loci and 0.40 for mitochondria. The F, G and R statistics indicate highly restricted gene flow among G. m. morsitans populations separated over geographic scales of 12–917 km. 相似文献
7.
E. A. Salmenkova V. T. Omel’chenko K. I. Afanas’ev G. A. Rubtsova 《Journal of Ichthyology》2008,48(4):313-325
The estimates of genetic diversity in populations of chum salmon Oncorhynchus keta from different regions of Sakhalin Island, Iturup Island, and the Anadyr’ River were obtained on the basis of analysis of allozyme variability. These estimates together with our published earlier data on chum salmon from the Amur River basin and the rivers of the northern coast of the Sea of Okhotsk demonstrate pronounced regional genetic differentiation in the Asian part of the fish range. The intraregional level of interpopulation genetic diversity was maximum on Sakhalin Island (G ST = 6.6%) and was small on Iturup Island (G ST = 0.9%) and the northern coast of the Sea of Okhotsk (G ST = 0.6%). Interpopulation genetic diversity of Sakhalin chum salmon was almost commensurable to the diversity of the whole pool of studied Asian populations (G ST = 7.6%) and would be presented more completely in baselines assigned for genetic identification of mixed stocks. It was demonstrated that the character and degree of genetic differentiation between populations of chum salmon from the main hatcheries situated in different regions of the Sakhalin oblast and connected to one another by numerous transplantations of fertilized eggs did not change significantly during an approximately 20-year period of our observation, and this fact suggests low efficiency of such transplantations. 相似文献
8.
O. M. Fedorenko M. V. Gritskikh I. E. Malysheva T. S. Nikolaevskaya 《Russian Journal of Genetics》2009,45(9):1134-1138
In natural populations of Festuca pratensis Huds. from the islands of Onega Lake, the level of genetic diversity was evaluated. In three populations variability of 64
RAPD loci was tested. The level of genetic diversity (P
95% = 30.2; H
exp = 0.093) was low for a cross-pollinating plant species. Furthermore, genetic similarity between the plants from insular populations
was found to be high (I
N = 0.887). It was demonstrated that genetic variation among the population accounted for at most 5.3% of total genetic diversity,
which, however, was higher than the F
ST values for continental populations (F
ST = 0.022). It was suggested that specific features of the genetic structure of insular population, i.e., low gene diversity
within the populations along with high differentiation among the populations, were caused by the gene flow attenuation, as
a result of isolation, and intensification of inbreeding. These features had negative effect on total population adaptation. 相似文献
9.
A genetic analysis of nuclear DNA was performed by inter-simple sequence repeat-polymerase chain reaction (ISSR-PCR) technique
on 32 populations of Ageratina adenophora, an invasive triploid weed in China. Among the 100 ISSR markers detected, 12 showed genetic variation both within and among
the populations. Among the 446 amplified bands, 93.5% were found polymorphic. Most individuals (99%) displayed a unique ISSR
fingerprint pattern, which yielded a high level of polymorphism (P
o = 93.5%) and genetic diversity (Nei’s H
T = 0.2354). The estimates of population variation, based on ISSR-PCR, were high, as measured by the analysis of molecular
variance (AMOVA, F
ST = 0.3140), the Wright’s F-statistics (G
ST = 0.3453), and the Shannon’s information index (H
sp = 0.3716). AMOVA revealed 68.6% genetic variation within the populations and 91.2% within the provinces. The Mantel test
showed that genetic distance was significantly correlated with geographic distance.
Published in Russian in Fiziologiya Rastenii, 2009, Vol. 56, No. 3, pp. 453–459.
This text was submitted by the authors in English. 相似文献
10.
Dysosma pleiantha, an important threatened medicinal plant species, is restricted in distribution to southeastern China. The species is capable
of reproducing both sexually and asexually. In this study, inter-simple sequence repeat marker data were obtained and analyzed
with respect to genetic variation and genetic structure. The extent of clonality, together with the clonal and sexual reproductive
strategies, varied among sites, and the populations under harsh ecological conditions tended to have large clones with relatively
low clonal diversity caused by vegetative reproduction. The ramets sharing the same genotype show a clumped distribution.
Across all populations surveyed, average within-population diversity was remarkably low (e.g., 0.111 for Nei’s gene diversity),
with populations from the nature reserves maintaining relatively high amounts of genetic diversity. Among all populations,
high genetic differentiation (AMOVA: ΦST = 0.500; Nei’s genetic diversity: G
ST = 0.465, Bayesian analysis: ΦB = 0.436) was detected, together with an isolation-by-distance pattern. Low seedling recruitment due to inbreeding, restricted
gene flow, and genetic drift are proposed as determinant factors responsible for the low genetic diversity and high genetic
differentiation observed. 相似文献
11.
Knowledge of the amount and patterns of genetic variation within and among populations of mangrove trees is essential for devising optimum genetic management strategies for their conservation and sustainable utilization. Ceriops tagal is a widespread viviparous mangrove. Genetic diversity in the species was examined with inter-simple sequence repeat (ISSR). Nine natural populations were collected from Thailand and China. The estimates of genetic variation were extremely low (HT = 0.0179 ± 0.005, HS = 0.0084 ± 0.001), and only 47% of the total gene diversity was maintained within populations (GST = 0.529). The eastern coastal populations of Thailand were more similar to populations from China than to populations from the western coastline of Thailand. A high level of Nei's genetic identity exists between populations of C. tagal (I = 0.989), suggesting their common ancestry. The low levels of genetic diversity in the species may result from a series of genetic bottlenecks during several glacial epochs. 相似文献
12.
Mao-feng Yue Ren-chao Zhou Ye-lin Huang Guo-rong Xin Su-hua Shi Li Feng 《Journal of Plant Biology》2010,53(2):165-171
High levels of genetic variation enable species to adapt to changing environments and provide plant breeders with the raw
materials necessary for artificial selection. In the present study, six AFLP primer pairs were used to assess the genetic
diversity of Desmodium triflorum (L.) DC. from 12 populations in South China. A high percentage of polymorphic loci (P = 76.16%) and high total gene diversity (H
T = 0.310) were found, indicating that the genetic diversity of D. triflorum is high at the species level. Genetic diversity was also relatively high at the population level (P = 55.85%, H
e = 0.230). The coefficient of gene differentiation among populations (G
ST) was 0.255, indicating that while most genetic diversity resided within populations, there was also considerable differentiation
among populations. AMOVA also indicated 24.29% of the total variation to be partitioned among populations (ΦST = 0.243). UPGMA clustering analysis based on genetic distances showed that the 12 populations could be separated into three
subgroups: an eastern, a western, and a central-southern subgroup. However, a Mantel test revealed no significant correlation
(r = 0.286, p = 0.983) between the geographical distances and genetic distances separating these populations; mountain barriers to gene
flow and human disturbance may have confounded these correlations. The present study has provided some fundamental genetic
data that will be of use in the exploitation of D. triflorum. 相似文献
13.
The genetic variation within and among eight Tunisian natural populations of Lavandula multifida L., from different bioclimatic zones was assessed using random amplified polymorphic DNA (RAPDs). Of a total of 97 generated bands from seven selected primers, 84 bands were polymorphic. The genetic diversity within a population was high and varied according to the populations (0.308 < H’ < 0.459) without relationships to altitudes or pluviothermic indices of sites. The genetic differentiation among populations was high (GST = 0.395 and ΦST = 0.318). All population pairs were significantly differentiated. Among populations, within ecological groups genetic structure was high (0.219); whilst among them it was low (ΦCT = 0.049; P < 0.05). The correlation between ΦST and geographic distance matrices among pairs of populations was not significant, suggesting that genetic connectivity between populations has a stochastic component at all spatial scales. The neighbour‐joining cluster analysis showed that individuals from each population clustered together. UPGMA cluster analysis showed that population groupings are not strictly in accordance with bioclimates or geographic location. The genetic differentiation in L. multifida could have occurred at local scales because of genetic drift. Efforts should be made to protect all populations. The maintenance of substantial population size should be initiated via fencing and controlling collection to restore the regeneration of populations. 相似文献
14.
Xiao-Li Peng Chang-Ming Zhao Gui-Li Wu Jian-Quan Liu 《Trees - Structure and Function》2007,21(4):457-464
Repeated cycles of retreat and recolonization during the Quaternary ice ages are thought to have greatly influenced current
species distributions and their genetic diversity. It remains unclear how this climatic oscillation has affected the distribution
of genetic diversity between populations of wind-pollinated conifers in the Qinghai-Tibetan region. In this study, we investigated
the within-species genetic diversity and phylogenetic relationships of Picea likiangensis, a dominant forest species in this region using polymorphic DNA (RAPD) markers. Our results suggest that this species has
high overall genetic diversity, with 85.42% of loci being polymorphic and an average expected heterozygosity (H
E) of 0.239. However, there were relatively low levels of polymorphism at population levels and the differences between populations
were not significant, with percentages of polymorphic bands (PPB) ranging from 46.88 to 69.76%, Nei’s gene diversity (H
E) from 0.179 to 0.289 and Shannon’s indices (Hpop) from 0.267 to 0.421. In accordance with our proposed hypothesis, a high level of genetic differentiation among populations
was detected based on Nei’s genetic diversity (G
ST = 0.256) and AMOVA analysis (Phi
st = 0.236). Gene flow between populations was found to be limited (Nm = 1.4532) and far lower than reported for other conifer species with wide distribution ranges from other regions. No clusters
corresponding to three morphological varieties found in the south, north and west, respectively, were detected in either UPGMA
or PCO analyses. Our results suggest that this species may have had different refugia during the glacial stages in the southern
region and that the northern variety may have multiple origins from these different refugia. 相似文献
15.
Man Kyu Huh Hak Young Lee Shambhu Nath Mishra Hong Wook Huh 《Journal of Plant Biology》2000,43(3):136-142
We determined the genetic diversity and population structures ofCarex breviculmis (Cyperaceae) populations in Korea, using genetic variations at 23 allozyme loci.C. breviculmis is a long-lived herbaceous species that is widely distributed in eastern Asia. A high level of genetic variation was found
in 15 populations. Twelve enzymes revealed 23 loci, of which 11 were polymorphic (47.8%). Genetic diversity at the speciesand
population levels were 0.174 and 0.146, respectively. Total genetic diversity (HT = 0.363) and within-population genetic diversity (Hs = 0.346) were high, whereas the extent of the population divergence was relatively low (GST = 0.063). Deviation from random mating (Fis) within the 15 populations was 0.206. An indirect estimate of the number of migrants
per generation(Nm = 3.69) indicated that gene flow was extensive among Korean populations of this species. Analysis of fixation indices revealed
a substantial heterozygote deficiency in some populations and at some loci. Genetic identity between popu-lations was high,
exceeding 0.956. 相似文献
16.
Genetic variation and structure of ten wild, three domesticated and one wild-cultivated populations of pepper (Capsicum annuum) from northwestern Mexico were studied in order to find out if the domestication process has reduced the genetic variation
of the modern cultivars of this species. The analysis was based on 12 polymorphic loci from nine isozymes. Wild populations
were sampled in different habitats along a latitudinal gradient of ca. 500 km. All populations had high genetic variation
(i.e. wild: A = 2.72, P = 90.8%, He = 0.445; wild-cultivated: A = 2.50, P = 92.3%, He = 0.461; domesticated: A = 2.60, P = 84.6%, He = 0.408), indicating little genetic erosion in modern cultivars of pepper. Genetic diversity estimated by Nei's method showed
that most genetic variation is found within, rather than among populations. However, genetic differentiation is greater among
cultivated (G
ST=0.167) than among wild (G
ST=0.056) populations. Wild populations had an average genetic identity (I) of 0.952, indicating little differentiation and high gene flow (Nm=4.21) among these populations. Average genetic identity between wild and domesticated populations was of I=0.818, revealing that the domestication process has modified the genetic composition of commercial varieties of pepper. Changes
in genetic composition among commercial varieties seem to have occurred in different directions, as indicated by the average
value of I = 0.817 among these populations. The high level of diversity found in wild populations of C. annuum suggests that the wild relatives of cultivated peppers are a valuable genetic resource which must be conserved.
Received May 5, 1999 Accepted October 30, 2000 相似文献
17.
The East Himalaya-Hengduan Mountains region is the center of diversity of the genus Primula, and P. sikkimensis is one of the most common members of the genus in the region. In this study, the genetic diversity and structure of P. sikkimensis populations in China were assessed using inter-simple sequence repeat (ISSR) and chloroplast microsatellite markers. The
254 individuals analyzed represented 13 populations. High levels of genetic diversity were revealed by ISSR markers. At the
species level, the expected heterozygosity and Shannon’s index were 0.4032 and 0.5576, respectively. AMOVA analysis showed
that 50.3% of the total genetic diversity was partitioned among populations. Three pairs of chloroplast microsatellite primers
tested yielded a total of 12 size variants and 15 chloroplast haplotypes. Strong cpDNA genetic differentiation (G
ST = 0.697) and evidence for phylogeographic structure were detected (N
ST = 0.788, significantly higher than G
ST). Estimated rates of pollen-mediated gene flow are approximately 27% greater than estimated rates of seed-mediated gene flow
in P. sikkimensis. Both seed and pollen dispersal, however, are limited, and gene flow among populations appears to be hindered by the patchiness
of the species’ habitats and their geographic isolation. These features may have played important roles in shaping the genetic
structure of P. sikkimensis. A minimum-spanning tree of chloroplast DNA haplotypes was constructed, and possible glacial refugia of P. sikkimensis were identified. 相似文献
18.
Abdennacer Boulila Afef Béjaoui Chokri Messaoud Mohamed Boussaid 《Biochemical genetics》2010,48(1-2):57-70
Random amplified polymorphic DNA markers were used to assess the genetic diversity within and among seven Tunisian diploid and polyploid populations of Teucrium polium L. from five bioclimatic areas. Out of the 141 bands generated from eight selected primers, 124 were polymorphic. The genetic diversity within a population (Shannon’s index) was high and varied according both the ploidal levels and bioclimatic zones. The genetic differentiation among populations assessed by G ST and ΦST statistics was high, suggesting a low level of gene flow among them. The major proportion of the variation was attributable to individual differences within populations. The UPGMA analysis based on Nei and Li’s coefficient showed that individuals from each population clustered together. In a dendrogram using the ΦST distance matrix, population grouping is concordant with bioclimates and cytotypes. Conservation strategies should take into account the level of the genetic diversity of the populations according to their bioclimate and ploidal levels. 相似文献
19.
Genetic variation in Pueraria lobata (Fabaceae), an introduced, clonal, invasive plant of the southeastern United States 总被引:1,自引:0,他引:1
Pueraria lobata (kudzu), a clonal, leguminous vine, is invading the southeastern United States at a rate of 50 000 ha per year. Genetic variability and clonal diversity were measured in 20 southeastern U.S. populations using 14 allozyme loci. Within its U.S. range, 92.9% of the loci were polymorphic and overall genetic diversity was 0.290. Such high levels of genetic diversity are consistent with its history of multiple introductions over an extended period of time. The average proportions of polymorphic loci and genetic diversity within populations were 55.7% (range = 28.6–85.7%) and 0.213 (range = 0.114–0.317), respectively. The proportion of total genetic diversity found among populations was similar to species with equivalent life history characters (GST = 0.199). No regional patterns of variation were seen. The number of putative genotypes in each population ranged from 2 to 26. Mean genotypic diversity was 0.694, ranging from 0.223 to 0.955. Such high levels of genotypic diversity indicate that local sites are often colonized by several propagules (most likely seeds) and/or that sexual reproduction occurs within populations after establishment. An excess of heterozygosity was observed in populations with few unique genets, implying that selection for highly heterozygous individuals may occur in populations of P. lobata. 相似文献
20.
Yizhong Duan Qingbo Gao Faqi Zhang Yinghu Li Pengcheng Fu Shilong Chen 《Nordic Journal of Botany》2011,29(5):615-624
The phylogeography of Sibiraea angustata, an endemic shrub species, was studied in the Qinghai–Tibet plateau (QTP). We investigated 466 individuals of S. angustata from 39 populations basically covering its total distribution area. Eight haplotypes (A–H) were detected by sequencing the intergenic chloroplast spacer trnS–trnG (600 bp), and one ancestral haplotype (A) was found to be widely distributed. The level of differentiation among populations was very high (GST=0.768; NST=0.850) and a significant phylogeographical structure was revealed (NST>GST). Analysis of molecular variance (AMOVA) similarily revealed a high level of differentiation among populations (84%, FST=0.842), indicating that little gene flow has occurred among populations mutually isolated by high mountains and rivers in the QTP. On the QTP platform there was only one widespread haplotype (A) in most populations, while populations along the eastern and southeastern edges had high diversity and unique haplotypes. Our results suggest that a glacial refugium may have been located on the eastern or southeastern edges of QTP during the last glaciation, and that interglacial and postglacial range expansion occurred from that refugium. Nested clade analysis (NCA) also suggests this scenario, which indicates that the current spatial distribution of cpDNA haplotypes and populations mainly resulted from long distance colonization, possibly coupled with subsequent or past fragmentation followed by range expansion and allopatric fragmentation. 相似文献