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1.
Genetic and genotypic diversity found within populations of threatened plant species can have important implications for their conservation and management. In this study we describe genetic and genotypic diversity found within 10 populations of the endemic shrub Elliottiaracemosa (Ericaceae), the Georgia plume. E. racemosa is a threatened species known from fewer than 50 locations, all within the state of Georgia, USA. Seedset is limited to nonexistent in some E. racemosa populations and sexual recruitment has not been documented. However, the species is known to spread vegetatively via root-sprouts. Twenty-one allozyme loci were resolved for E. racemosa, nine of which were polymorphic. Compared with other woody taxa, E. racemosa has low genetic (i.e. allelic) diversity within populations (Hep = 0.063) and at the species level (Hes = 0.091). Most of the genetic variation (82%) was found within populations, and genetic identities between populations were high (mean I = 0.96). However, genotypic diversity (i.e. the number of multilocus genotypes) differed markedly among populations. Two of the 10 populations consisted almost entirely of single multilocus genotypes, whereas more than 20 multilocus genotypes (in samples of 48 stems) were detected at three sites. Sites in which few multilocus genotypes were detected have low seedset, suggesting that the lack of clonal diversity limits reproduction in some populations of this reportedly self-incompatible species. 相似文献
2.
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
3.
Shang-Yin Vanson Liu Hon-Tsen Yu Tung-Yung Fan Chang-Feng Dai 《Coral reefs (Online)》2005,24(3):352-358
The identification of different clones is fundamental to the study of population structure among organisms with mixed reproductive
modes such as cnidarians. However, due to the low genetic variation of coral mtDNA and contamination by zooxanthellate DNA,
very few molecular markers are available for studying the clonal structure of cnidarians. Herein we used four polymorphic
loci of microsatellite DNA isolated from a zooxanthellae-free octocoral, Junceella juncea, to study its clonal structure in seven populations collected from three localities in Taiwan. In total, 40 multilocus genotypes
were found among 152 colonies, and the number of genotypes (clones) identified in the seven populations ranged from 2 to 16.
Each of the 40 multilocus genotypes was restricted to a single population, even where adjacent populations were only 100 m
distant. The ratio of observed to expected genotypic diversity (Go:Ge) ranged from 0.217 to 0.650, and Go showed a significant departure from Ge (p<0.05) at each site indicating that asexual fragmentation may play a major role in the maintenance of established populations.
Mean relatedness (R) values showed that genotypes within reefs were more closely related than those between regions. The results indicate that
microsatellites are useful for discerning the clonal structures among and within populations at different spatial scales.
Electronic supplement: Unique multilocus genotypes (clones) revealed by 4 polymorphic loci for Junceella juncea colonies collected from Xiashuijui (Reefs A, B, C, Transplant, Transect), Nanwan and Shicheng 相似文献
4.
Plant clonality may greatly reduce effective population size and influence management strategies of rare and endangered species. We examined genetic diversity and the extent of clonality in four populations of the monotypic herbaceous perennial Japonolirion osense, which is one of the most rare flowering plants in Japan. Allozyme analysis revealed moderate levels of genetic variation, and the proportion of polymorphic loci (P=66.7%) was higher than the value for species with similar life-history traits. With four polymorphic loci, 19 multilocus genotypes were observed among 433 aerial shoot samples and 10 (52%) were found only in single populations. The proportion of distinguishable genotypes (PD=0.10) and Simpson's index of diversity (D=0.52) also exhibited moderate levels of genotypic diversity compared to other clonal plants, with genotype frequencies at Hardy-Weinberg equilibrium. The distributions of genotypes were often localized and they were mostly found within a radius of 5 m. Spatial autocorrelation analysis showed that shoot samples located 4 m apart were expected to be genetically independent. The results suggest that the spatial extent of genets was relatively narrow and thus the clonality was not extensive. 相似文献
5.
The genetic structure of populations of the clone-forming tropical terrestrial bromeliad, Aechmea magdalenae, was examined by electrophoretic analyses in nine populations occurring on and near Barro Colorado Island, Republic of Panama. For the nine populations as a whole, 33% of the loci were polymorphic and the genetic diversity was 0.121. Within populations, the mean percent of polymorphic loci was 24.1% and the mean genetic diversity was 0.084. About one-third of the total allozyme diversity resided among populations (mean GST = 0.356). The distribution of A. magdalenae was patchy in the study area. This, coupled with the relatively small effective population sizes and the possible founding of populations by few individuals may have contributed to the large among-population component of genetic diversity. The extent of clonal growth was inferred by examining the relationship between the proportion of rosette-pairs sharing identical multilocus genotypes and distance between pairs. This method indicates that clonal spread is local; individuals sharing multilocus genotypes most often occur within 10 m of each other. 相似文献
6.
In southern Arizona the columnar cactus, Lophocereus schottii, inhabits desert riparian environments. Reproduction in this part of its range is predominantly asexual and occurs by either the dispersal of stems in the immediate vicinity of parents or the long-distance transport of detached stem pieces downstream by floodwaters. Genetic diversity and clonal structure of eight populations of L. schottii in Organ Pipe Cactus National Monument, Arizona, were examined. In all populations ramets were mapped and stem tissue from each ramet was examined electrophoretically. At the species level, 44.4% of the loci were polymorphic and the genetic diversity was 0.145. Within populations, the mean proportion of polymorphic loci and genetic diversity were 34.4% and 0.126%, respectively. Although most of the allozyme variation was within populations, appreciable heterogeneity was found among populations (GST = 0.130). Genetic and genotypic diversity was greatest in three of the four populations located in the principal area of L. schottii occurrence in the monument. Genotypic diversity was lowest in the smallest population and in the most isolated population. Ramets in all populations were spatially aggregated. Plant pairs with identical multilocus genotypes were usually ≤ 10 m apart, but some widely separated individuals had identical genotypes. Occasional long-distance dispersal of stems and the periodic recruitment of seedlings have caused genets to intermingle, promoting outcrossing and maintaining genetic diversity. 相似文献
7.
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
8.
O. Díaz B. Salomon R. von Bothmer 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,99(1-2):210-217
To gain information on the extent and nature of genetic variation in Elymus alaskanus, levels and distribution of genetic variation were assessed within and among 13 populations originating from Iceland, Norway,
Sweden and Russia using allozymes. The results showed that four (30.7%) of the 13 loci were polymorphic within the species,
while the mean percentage of polymorphic loci within the populations was 1.9%. The mean number of alleles per locus for the
species was 1.8 and 1.02 across the populations. Genetic diversity at the species level was low (H
es=0.135), and mean population diversity was notably lower (H
ep=0.005). A high degree of genetic differentiation was observed among populations. The salient points emerging from this study
are: (1) statistically significant differences were found in allele frequencies among populations for every polymorphic locus
(P<0.001), (2) the high mean coefficient of gene differentiation (G
ST) showed that 95% of the total allozyme variation was attributable to differences among populations, and (3) relatively high
genetic distances between the populations were obtained (mean D=0.16). The Norwegian populations had the highest genetic diversity
as compared with the other populations. Geographical comparisons revealed three different groups of populations clearly differentiated,
i.e. Scandinavia (Norway and Sweden), Iceland and Russia. Cluster and principal coordinates analyses revealed the same genetic
patterns of relationships among populations. Generally, this study indicates that E. alaskanus contains low allozymic variation in its populations. The implications of these results for the conservation of the species
are discussed.
Received: 23 October 1998 / Accepted: 19 December 1998 相似文献
9.
Melinda D. Peters Qiu-Yun Xiang David T. Thomas Jon Stucky Noah K. Whiteman 《Conservation Genetics》2009,10(1):1-14
Echinacea laevigata (Boynton and Beadle) Blake is a federally endangered flowering plant species restricted to four states in the southeastern
United States. To determine the population structure and outcrossing rate across the range of the species, we conducted AFLP
analysis using four primer combinations for 22 populations. The genetic diversity of this species was high based on the level
of polymorphic loci (200 of 210 loci; 95.24%) and Nei’s gene diversity (ranging from 0.1398 to 0.2606; overall 0.2611). There
was significant population genetic differentiation (GST = 0.294; ӨII = 0.218 from the Bayesian f = 0 model). Results from the AMOVA analysis suggest that a majority of the genetic variance is attributed to variation within
populations (70.26%), which is also evident from the PCoA. However, 82% of individuals were assigned back to the original
population based on the results of the assignment test. An isolation by distance analysis indicated that genetic differentiation
among populations was a function of geographic distance, although long-distance gene dispersal between some populations was
suggested from an analysis of relatedness between populations using the neighbor-joining method. An estimate of the outcrossing
rate based on genotypes of progenies from six of the 22 populations using the multilocus method from the program MLTR ranged
from 0.780 to 0.912, suggesting that the species is predominantly outcrossing. These results are encouraging for conservation,
signifying that populations may persist due to continued genetic exchange sustained by the outcrossing mating system of the
species. 相似文献
10.
Genetic variation within, and divergence among, populations of the liverwortConocephalum conicum were estimated from the study of 17 populations and 23 putative gene loci. Two additional multilocus genotypes (“T” and “FS”)
were detected in Japan, along with the previously reported “J” type. These three multilocus genotypes differed both morphologically
and ecologically. All eight populations from western Japan included only the J-type and exhibited low genetic variation within
populations: Nei's (1973) average gene diversity (Ĥ)=0.080±0.029. In contrast, co-occurrence of several multilocus genotypes in each population from the Kanto District resulted
in much higher levels of genetic variation (Ĥ=0.218±0.037). If the three genotypes are distinguished,Ĥ values are 0.113±0.030 for T-type, 0.107±0.033 for FS-type, and 0.083±0.018 for J-type. UsingC. japonicum, which showed low genetic variation (0.014±0.010) as an outgroup, each genotype formed a monophyletic clade, and the J- and
FS-types were more closely related to each other than to the T-type. Populations of western Japan and the Kanto District also
differed in the degree of gene diversity among populations, but the reasons for these differences are obscure. 相似文献
11.
Genetic diversity and population differentiation of chestnut blight fungus, Cryphonectria parasitica, in China as revealed by RAPD 总被引:1,自引:0,他引:1
Seventeen Cryphonectria parasitica populations sampled from six regions in China were investigated using RAPD. Across all 169 isolates from the 17 populations
evaluated, 52 of the 71 markers (73%) were polymorphic, total genetic diversity (h) was 0.1463, and Shannon’s index was 0.2312. Diversity within populations accounted for 74% of total genetic diversity, and
genetic differentiation among populations was 0.26 (G
ST = 0.26). Gene flow was 1.4 among the populations; higher gene flow was found among populations within regions and among regions
[N
m (G
SR) = 2.8 and N
m (G
RT) = 3.5]. The unweighted pair group mean analysis (UPGMA) dendrogram revealed two distinct clusters: the northern China group
and the southern China group. The spatial autocorrelation analysis revealed that the variation at most loci was randomly distributed
and lacked spatial structure, but several loci and closer distances were spatially structured. Human activity and habitat
could also be important factors affecting genetic structure among C. parasitica populations in China. Genetic diversity was highest in Southwest China, descending in an orderly fashion to Northeast China.
This pattern indicated that Southwest China might be the center of origin of C. parasitica in China. The present study provides useful information for understanding the origin and spread of chestnut blight fungus
in China and valuable data for formulating relevant strategies for controlling the disease in China. 相似文献
12.
We investigated the extent of genetic differentiation among populations of fujihatazao,Arabis serrata along an altitudinal gradient at Mt. Fuji in Shizuoka Prefecture. This species is a perennial plant, widely distributed in
Japan forming small isolated populations. However, at Mt. Fuji, this species constitutes a large population distributed from
1440 to 2400 m altitude. A total of 411 individuals were sampled from ten subpopulations. Eighteen loci were detected on eleven
enzyme systems. Eleven loci were monomorphic and seven loci were polymorphic with a mean of 2.11 alleles per loci. Nei's genetic
distance (mean 0.01) and genetic identity (mean 0.968) were very similar among populations indicating a low genetic differentiation.
The total genetic diversity (H
T
) estimated for the polymorphic loci was, in average, 0.396. The mean gene differentiation (GST=0.091) was very low. Gene frequency of seven polymorphic loci was analyzed by spatial autocorrelation methods based on Moran's
indexes. Only Pgi-3 exhibited a significant negative autocorrelation (−0.160;P<0.05); other loci values ranged from −0.134 to 0.027. Gene flow estimated by indirect methods varied between genes but most
of the values were high (meanNm=20.8) suggesting that subpopulations at different altitudes are probably connected. Despite plants at different altitudes
present different ecological traits (e.g., differences in phenology, growth and reproductive traits), subpopulations ofA. serrata are still low differentiated, at least for the loci studied. This may be explained by the recent origin of some habitats
(e.g., second crater and surrounded areas) in this locality. 相似文献
13.
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
14.
A cline of allozyme variation inAbies mariesii 总被引:1,自引:0,他引:1
Genetic variation at 22 allozyme loci was examined for 1,003 trees from 11 isolated natural populations ofAbies mariesii covering all except the southernmost region of its geographic range. Genetic diversity within species (H
es=0.063) was low compared to many other long-lived woody species. Most of the genetic variation is found within populations
(G
ST=0.144) despite their isolated distribution. Genetic distance between populations was positively correlated with geographic
distance. Genetic diversity within populations was generally low (meanH
ep=0.054), but varied across populations in a clinal fashion such that genetic variation decreased with increasing latitude.
These genetic characteristics may reflect the distribution history of this species. 相似文献
15.
Pedro A. Sosa Miguel A. González-Pérez Claudio Moreno Jake B. Clarke 《Conservation Genetics》2010,11(6):2357-2368
Five polymorphic microsatellites (simple sequence repeat; SSR) markers were used to estimate the levels of genetic variation
within and among natural populations from different islands of the endangered endemic from the Canary Islands Sambucus palmensis Link (Sambucaceae). Genetic data were used to infer potential evolutionary processes that could have led to present genetic
differentiation among islands. The levels of genetic variability of S. palmensis were considerably high; proportion of polymorphic loci (P = 100%), mean number of alleles per locus (A = 6.8), average expected
heterozygosity (He = 0.499). In spite of its small population size and endemic character, 58 different multilocus genotypes
were detected within the 165 individuals analyzed. All samples located in different islands always presented different multilocus
genotypes. Principal Coordinates Analysis, genetic differentiation analysis (F
ST and G
ST
′) and Bayesian Cluster Analysis revealed significant genetic differences among populations located in different islands. However,
this genetic differentiation was not recorded among Tenerife and La Gomera populations, possibly revealing the uncontrolled
transfer of material between both islands. AMOVA analysis attributed 77% of the variance to differences within populations,
whereas 8% was distributed between islands. The levels of genetic differentiation observed among populations, and the genetic
diversity distribution within populations in S. palmensis, indicate that management should aim to conserve as many of the small populations as possible. Concentrating conservation
efforts only on the few large populations would result in the likelihood of loss of genetic variability for the species. 相似文献
16.
Genetic variation and gene flow in the scleractinian coral Goniastrea aspera (Verrill), found around the north–south Okinawa Islands, were studied using allozyme and starch gel electrophoresis. The relative contribution of sexual and asexual reproduction to recruitment was determined. Analysis of multilocus genotypes of samples, collected at least 3 m apart, identified a high number of unique genotypes (NG) relative to the number of individuals sampled (N) (mean NG: N=0.97±0.03 [SD]), and also highly observed genotypic diversity (GO) relative to expected genotypic diversity under Hardy–Weinberg equilibrium (GE) (mean GO: GE=0.95±0.06 [SD]). These results suggest that the collected G. aspera propagated predominantly by sexual reproduction in Okinawan populations. The UPGMA grouping of five populations in the Okinawa, based on Neis unbiased genetic distance, showed two clusters that were south and north Okinawa populations. AMOVA analyses that incorporated the data of populations from the Kerama and the Ishigaki Islands detected significant FSC values among the populations within groups in analyses distinguishing north–south Okinawa, Okinawa–Kerama, and Okinawa–Kerama–Ishigaki. Significant FCT values were neither detected between north–south Okinawa nor between the Okinawa–Kerama groups. The local-recruits hypothesis, which assumes that a substantial proportion of recruits is produced locally, appears to be applicable to coral populations in the Ryukyu Archipelago. On the other hand, detection of nonsignificant FCT values indicated the presence of genetic connectivity between north–south Okinawa and Kerama–Okinawa groups. 相似文献
17.
Enzyme electrophoreses were used to estimate genetic variation in five populations of Epipactis helleborine from two National Parks (Biebrza and Wigry) in northeast Poland. It has been proved that populations from these two regions differed in genetic structure, with the populations belonging to the Biebrza group having a higher level of genetic variation than those from Wigry. The number of polymorphic loci (P) ranged from 18.2% to 40.9% and the mean number of alleles per polymorphic locus (Ap) from 2.25 to 2.80. Although the observed heterozygosity (Ho) was lower than the expected one (He) in each population, the values of Ho and He were 2–3 times lower in the populations from Wigry than in those from Biebrza. Excluding the LUK population with the smallest genotypic diversity, the majority of 345 distinct multilocus genotypes occurred only once, sporadically 2–4 times in each population and their frequency ranged from 0.2% to 3.7%. Moreover, factors shaping genetic structure of E. helleborine and their intensity varied in the populations studied. Reproduction from seeds seems to influence greatly the genetic variation of the populations from the Biebrza National Park, while an assortative mating between related individuals or population size appears to be more important in the case of the populations from the Wigry National Park. 相似文献
18.
Baoying Guo Congxin Xie Shunping He Khalid Abbas Huanling Wang Dongmei Xiong Huijuan Zhang Xin Tong 《Environmental Biology of Fishes》2009,85(3):201-206
We determined the genetic diversity of geographic populations from three spawning grounds (Nyang River, Lhasa River, Shetongmon
Reach of Yarlung Zangbo River) of Glyptosternum maculatum with amplified fragment length polymorphism (AFLP) markers. Five primer combinations detected 332 products, 51 of them (15.4%)
were polymorphic in at least one population. The Shetongmon population was found to be the richest in genetic diversity as
was indicated by the percentage of polymorphic loci and heterozygosity, followed by the Nyang population and the Lhasa population.
The pair-wise genetic distance between populations were all very close, ranging from 0.0015 to 0.0042 with an average of 0.0024.
The genetic distance was not proportional to the geographic distance. The analysis of molecular variance demonstrated that
all variation occurred within populations. The average estimated fixation index (F
st) of three populations across all polymorphic loci was −0.0184, indicating the absence of genetic differences among the three
sampled populations. The differentiation among populations was not significant, and population structure was weak. Our observations
will help identify the genetic relationship among populations as the first approach to understand the genetic diversity of
Glyptosternum maculatum. 相似文献
19.
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
20.
Multilocus structure in Pinus contorta Dougl. 总被引:13,自引:0,他引:13
R.-C. Yang F. C. Yeh 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1993,87(5):568-576
We studied isozyme variation at 21 loci in 66 populations from three subspecies of Pinus contorta Dougl.; 35 in spp. latifolia, 20 in spp contorta and 11 in spp. murrayana. The objectives were to assess gametic disequilibria and multilocus structure. There was considerable differentiation of allele frequencies at 19 polymorphic loci across the 66 populations and within the subspecies. Allele frequencies at many loci correlated with geographic variables. Genetic variability varied considerably among populations within subspecies but the subspecies means were similar. The mean number of polymorphic loci and the mean heterozygosity over 19 polymorphic loci were, respectively, 13 and 0.194 in latifolia, 12 and 0.196 in murrayana, and 12 and 0.180 in contorta. The mean heterozygosity correlated with longitude and altitude across the 66 populations and with latitude in latifolia. Gametic disequilibria were evident in 40 populations; 29 in latifolia, eight in murrayana and three in contorta. Gametic disequilibria correlated with latitude across the 66 populations and with longitude in latifolia. The single-locus F
ST averaged 0.0339 in latifolia, 0.0567 in murrayana, and 0.0764 in contorta. The multilocus F
STM was 0.1227 in latifolia, 0.2926 in murrayana, and 0.3328 in contorta. Multilocus Wahlund and founder effects, migration patterns, and natural selection, probably played significant roles in generating and maintaining the multilocus genetic structure in P. contorta in general and the subspecies latifolia in particular. 相似文献