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1.
Morphological, phytochemical and genetic differences were studied to evaluate the level and distribution of diversity in twelve populations of the Portuguese endangered medicinal plant Mentha cervina L. Morphological variation was correlated with ecological conditions at the site of origin. Pulegone was the major essential oils compound in all of the populations collected at full flowering (68–83%), in different growing conditions (51–82%), and for all the developmental stages studied (47–82%). Although clusters were defined, the analysis revealed a high chemical correlation among all populations (Scorr ≥ 0.95%). Inter-simple sequence repeats markers were used to assess the population structure and genetic variation. Populations exhibited a relatively low genetic diversity (PPB = 14.3–64.6%, He = 0.051–0.222, I = 0.076–0.332), with high structuring between them (GST = 0.51). However, the genetic diversity at species level was relatively high (PPB = 97.7%; He = 0.320). The levels and patterns of genetic diversity were assumed to result largely from a combination of evolutionary history and its unique biological traits, such as breeding system, clonal growth, low capacity of dispersion and habitat fragmentation. The relatively low genetic diversity in the populations analyzed indicates that the maintenance of their evolutionary potential is at risk if population sizes are maintained and if there is no protection of the habitats.  相似文献   

2.
In order to investigate the genetic diversity and population structure of Stipa bungeana under the background of grassland utilization and grazing exclusion, ten S. bungeana populations were selected from different steppe type in the Loess Plateau of China. Sequence-related amplified polymorphism (SRAP) marker was used to assess the genetic diversity. Fifteen SRAP primer combinations generated a total of 482 amplification bands, 418 (86.72%) were polymorphic bands. A relatively high level of genetic diversity (PPB = 89.80%, h = 0.1972, H = 0.3154) was detected at the species level, but the genetic diversity was low at the population level (PPB = 17.01–33.33%, h = 0.0438–0.0967, H = 0.0361–0.1447). AMOVA analysis revealed a high level of genetic differentiation among populations (ΦST = 0.6757), and a limited among-population gene flow (Nm = 0.1200). There was no significant correlation between genetic distance and geographic distance by Mantel test (r = 0.1126, P = 0.204). Conservation implications were proposed for S. bungeana.  相似文献   

3.
Rhamnus persicifolia Moris is an endemic small tree belonging to the Rhamnus cathartica group, growing along mountainous streams of Central-Eastern Sardinia (Italy). ISSR markers were used to detect the genetic diversity within and among six populations representative of the species distribution range. In spite of the limited distribution of this endemic taxon, fairly high levels of genetic diversity were detected. Percentage of polymorphic bands (PPB), gene diversity (HS and HT) and Shannon information measure (Sh) were calculated both at population (PPB = 30.70%, HS = 0.1105, Sh = 0.1646) and at species level (PPB = 68.42%, HT = 0.2066, Sh = 0.3139).The existence of a spatial distribution of genetic diversity in R. persicifolia was revealed by a low gene flow, a fairly high level of genetic differentiation (GST = 0.4583) among populations and a positive correlation between genetic and geographic distances (Mantel test, r = 0.71, p = 0.016). The spatial genetic structure was also confirmed with BAPS analysis. Our results show that a certain level of isolation by distance and sex-ratio bias may explain the distribution of genetic diversity among populations.Conservation measures are suggested on the basis of the genetic diversity detected, by implementing an integrated in situ and ex situ conservation program for each population, in order to ensure effective protection for this endemic species.  相似文献   

4.
Swertia tetraptera Maxim is an annual alpine herb endemic to the Qinghai-Tibetan Plateau (QTP). Its populations are locally scattered as isolated patches throughout this region. Genetic variation within and among thirty-four populations of this species was assessed using ISSR fingerprinting with 10 primers. High levels of genetic diversity exist within species (P = 98.9%, I = 0.3475; He = 0.2227), while the within-population diversity is low (P = 32.7%, I = 0.177; He = 0.12). High levels of genetic differentiation were detected among populations based on various statistics, including Nei’s genetic diversity analysis (GST = 0.4608), Bayesian analysis (θB = 0.476) and AMOVA (FST = 0.57). That is, populations shared low levels of genetic identity (I = 0.2622–0.0966). This genetic structure was probably due to severe genetic drift, breeding system and limited gene flow. The observed genetic structure of the populations implies that different populations across the distribution range of the species should be sampled to maintain high genetic diversity when a conservation strategy is implemented.  相似文献   

5.
Genetic diversity analysis was conducted on 80 individuals of 4 populations of non-bred Pyropia haitanensis by simple sequence repeat (SSR) method. Using 15 pairs of microsatellite primers, 37 polymorphic loci were amplified, representing 94.9% of all loci. At the population level, the percentage of polymorphic bands (P) and polymorphism information content (PIC) were 66.67–84.62% and 0.481–0.488, with average value at 73.72% and 0.483, respectively. Expected heterozygosity (He) and Shannon's information index (I) were 0.279 and 0.434, respectively, at the species level, and 0.233 and 0.356 at population level. According to the coefficient of gene differentiation (GST), a large proportion of genetic variance (83.6%) of P. haitanensis was among individuals within populations, only 16.4% genetic variance was among populations, which was identified with the moderate gene flow value (Nm = 2.542). UPGMA clustered the 4 populations into 3 groups, and no significant correlation was found between the genetic distance and the corresponding geographic distance among the populations.  相似文献   

6.
For range‐restricted species with disjunct populations, it is critical to characterize population genetic structure, gene flow, and factors that influence functional connectivity among populations in order to design effective conservation programs. In this study, we genotyped 314 individuals from 16 extant populations of Ivesia webberi, a United States federally threatened Great Basin Desert using six microsatellite loci. We assessed the effects of Euclidean distance, landscape features, and ecological dissimilarity on the pairwise genetic distance of the sampled populations, while also testing for a potential relationship between Iwebberi genetic diversity and diversity in the vegetative communities. The results show low levels of genetic diversity overall (H e = 0.200–0.441; H o = 0.192–0.605) and high genetic differentiation among populations. Genetic diversity was structured along a geographic gradient, congruent with patterns of isolation by distance. Populations near the species’ range core have relatively high genetic diversity, supporting in part a central‐marginal pattern, while also showing some evidence for a metapopulation dynamic. Peripheral populations have lower genetic diversity, significantly higher genetic distances, and higher relatedness. Genotype cluster admixture results suggest a complex dispersal pattern among populations with dispersal direction and distance varying on the landscape. Pairwise genetic distance strongly correlates with elevation, actual evapotranspiration, and summer seasonal precipitation, indicating a role for isolation by environment, which the observed phenological mismatches among the populations also support. The significant correlation between pairwise genetic distance and floristic dissimilarity in the germinated soil seed bank suggests that annual regeneration in the plant communities contribute to the maintenance of genetic diversity in Iwebberi.  相似文献   

7.
Chinese pine (Pinus tabulaeformis carr.), endemic to China, is a conifer species with extensive and fragmented distribution in North China. In this study, the genetic diversity and structure of 20 natural populations of this species were investigated using amplified fragment length polymorphism (AFLP) markers. A total of 445 fragments were revealed with 8 pairs of primers, 379 (85.17%) of which were polymorphic. A moderate level of genetic diversity was detected at the species level (Shannon's information index I = 0.356, Nei's gene diversity HE = 0.271) and at the population level (I = 0.219, HE = 0.206). Most of genetic variation was within populations while a considerable level of genetic differentiation was detected (GST = 0.352, ФST = 0.304). The high differentiation could be attributed to the complex and fragmented habitats, and a limited gene flow among populations (Nm = 0.572). The Mantel test indicated that there was significant correlation (r = 0.455, P < 0.001) between Nei's genetic distance and geographical distance among all the populations. The results suggested that proper countermeasures should be taken to prevent the habitat further deterioration and maintain the genetic diversity of this species.  相似文献   

8.
Sinowilsonia henryi Hemsi., the only representative of the monotypic genus Sinowilsonia Hemsi. (Hamamelidaceae), is a threatened plant endemic to China with high phylogenetical, ecological and economical values. In the present study, inter-simple sequence repeat (ISSR) markers were employed to investigate the genetic diversity and differentiation of 214 individuals sampled from 14 populations. Fifteen selected primers yielded a total of 178 bright and discernible bands. The genetic diversity was low at the population level (h = 0.1025; I = 0.1506; PPL = 26.7%), but quite high at the species level (h = 0.2449; I = 0.3690; PPL = 72.5%). In line with the limited gene flow (Nm = 0.3537), the hierarchical analysis of molecular variance (AMOVA) revealed pronounced genetic differentiation among populations (ΦST = 0.6639). Furthermore, the Mantel test revealed a significant correlation between genetic and geographic distances among populations (r = 0.688, P = 0.001), indicating the role of geographic isolation in shaping its present population genetic structure. The present patterns of genetic diversity of S. henryi were assumed to result largely from its evolutionary history and geographic factors. Based on these findings, conservation strategies were proposed to preserve this threatened plant.  相似文献   

9.
The genetic diversity and structure of four Opisthopappus longilobus and nine Opisthopappus taihangensis populations from Mts. Taihang were analyzed using SRAP markers. The results showed that O. longilobus (PPB = 95.16%, H = 0.349, I = 0.517) and O. taihangensis populations (PPB = 94.58%, H = 0.332, I = 0.504) had high genetic diversity. The genetic diversity within populations varied according to two species. Low genetic differentiation was detected among O. longilobus (ΦST = 0.105) and O. taihangensis (ΦST = 0.188) populations, respectively. Significantly genetic variation was found between O. longilobus and O. taihangensis (ΦST = 0.232). The dendrogram generated from pairwise genetic distance among all populations showed two distinct clusters, each corresponding to one species. A Mantel test revealed insignificant positive correlation between genetic distances and geographic distances (rO. longilobus = 0.3021; rO. taihangensis = 0.3658; P > 0.05). Those results indicated that self-compatibility, effective gene flow, biological traits, and historical factors may be the main factors causing geographical differentiation in the structure of O. longilobus and O. taihangensis populations.  相似文献   

10.
ISSR markers were used to analyze the genetic diversity and genetic structure of eight natural populations of Cupressus chengiana in China. ISSR analysis using 10 primers was carried out on 92 different samples. At the species level, 136 polymorphic loci were detected. The percentage of polymorphic bands (PPB) was 99%. Genetic diversity (H e) was 0.3120, effective number of alleles (A e) was 1.5236, and Shannon’s information index (I) was 0.4740. At the population level, PPB = 48%, A e=1.2774, H e=0.1631, and I=0.2452. Genetic differentiation (G st) detected by Nei’s genetic diversity analysis suggested 48% occurred among populations. The partitioning of molecular variance by AMOVA analysis indicated significant genetic differentiation within populations (54%) and among populations (46%; P < 0.0003). The average number of individuals exchanged between populations per generation (N m ) was 0.5436. Samples from the same population clustered in the same population-specific cluster, and two groups of Sichuan and Gansu populations were distinguishable. A significantly positive correlation between genetic and geographic distance was detected (r=0.6701). Human impacts were considered one of the main factors to cause the rarity of C. chengiana, and conservation strategies are suggested based on the genetic characters and field investigation, e.g., protection of wild populations, reestablishment of germplasm bank, and reintroduction of more genetic diversity.  相似文献   

11.
Monimopetalum chinense Rehd. is an endangered woody vine endemic to eastern China. Using amplified fragment length polymorphism (AFLP) markers, we examined levels of genetic variation within and among eleven populations located across the species’ distribution. Although modest levels of heterozygosity were detected, other measures of genetic diversity registered relatively high levels of variability, both at the species level (P = 91.0%, HE = 0.232, IS = 0.365) and at the population level (P = 53.0%, HE = 0.155, IS = 0.239). Populations also exhibited high levels of genetic differentiation (Nei’s genetic diversity analysis, GST = 0.330), corresponding to isolation-by-distance and hierarchical population structure. These results indicate that, despite low levels of gene flow, populations of M. chinense still harbor substantial amounts of genetic diversity. Management plans for the species should include measures that ensure genetic diversity remains high within and among extant populations.  相似文献   

12.
Studies were performed to investigate the genetic variation of 14 natural populations of Gynostemma pentaphyllum (Thunb.) Makino, an outcrossing clonal plant species in China, using inter-simple sequence repeat (ISSR) markers. Fourteen selected primers were used to amplify DNA samples from 140 individuals, and totally 194 loci were detected. The percentage of polymorphic bands (PPBs) showed that the genetic diversity was pretty high at the species level (PPB = 96.39%) but quite low at the population level (PPB = 1.03–25.26%). Shannon's information index (I) and Nei's gene diversity (h) displayed a similar trend to PPB. According to the hierarchical analysis of molecular variance (AMOVA) and Nei's analysis of gene diversity, the percentages of genetic variation among populations were 88.66 and 88.94%, respectively, indicating a high level of inter-population genetic differentiation. The low levels of genetic diversity within populations and high genetic differentiation among populations were assumed to result from the limited gene flow, the clonal nature and genetic drift. Based on the genetic data, effective conservation strategies were proposed for conserving this traditional Chinese medicinal herb. Concerning the management of G. pentaphyllum, we suggested that in situ conservation be an important and practical measure for maintaining the genetic diversity and that a possibly maximum number of populations be conserved. Populations EMS and HLT, in which particularly low levels of genetic variation were characterized, should be given the priority for ex situ conservation.  相似文献   

13.
Sinopodophyllum hexandrum is an important medicinal plant whose genetic diversity must be conserved because it is endangered. The Qinling Mts. are a S. hexandrum distribution area that has unique environmental features that highly affect the evolution of the species. To provide the reference data for evolutionary and conservation studies, the genetic diversity and population structure of S. hexandrum in its overall natural distribution areas in the Qinling Mts. were investigated through inter-simple sequence repeats analysis of 32 natural populations. The 11 selected primers generated a total of 135 polymorphic bands. S. hexandrum genetic diversity was low within populations (average He = 0.0621), but higher at the species level (He = 0.1434). Clear structure and high genetic differentiation among populations were detected by using the unweighted pair group method for arithmetic averages, principle coordinate analysis and Bayesian clustering. The clustering approaches supported a division of the 32 populations into three major groups, for which analysis of molecular variance confirmed significant variation (63.27%) among populations. The genetic differentiation may have been attributed to the limited gene flow (Nm = 0.3587) in the species. Isolation by distance among populations was determined by comparing genetic distance versus geographic distance by using the Mantel test. Result was insignificant (r = 0.212, P = 0.287) at 0.05, showing that their spatial pattern and geographic locations are not correlated. Given the low within-population genetic diversity, high differentiation among populations and the increasing anthropogenic pressure on the species, in situ conservation measures were recommended to preserve S. hexandrum in Qinling Mts., and other populations must be sampled to retain as much genetic diversity of the species to achieve ex situ preservation as a supplement to in situ conservation.  相似文献   

14.
Taihangia rupestris Yu et Li is an endangered perennial herb endemic to China. Besides being at an important systematic position in the tribe Dryadeae, it also is a valuable wild flower resource. Inter-simple sequence repeat (ISSR) markers were employed to estimate the genetic diversity and genetic differentiation of ten populations. Relatively high genetic diversity was detected at species levels (PPB = 80.43; h = 0.2479; I = 0.3785). Most of the variation (73.51%) occurred within populations, and 26.49% was found among populations; Nei’s differentiation coefficient (Gst = 0.2435) supported this result. The Mantel test revealed a significantly positive correlation between geographical distance and genetic distance (r = 0.611, P < 0.001). The levels and patterns of genetic diversity of T. rupestris were assumed to result from its ancient origin and mixed reproductive modes. Based on these results, both ex situ and in situ conservation are proposed.  相似文献   

15.
《Aquatic Botany》2007,86(1):69-75
To obtain accurate estimates of population structure for purposes of conservation planning for wild lotus (Nelumbo nucifera Gaertn.) in central China, genetic diversity among and within six populations, and clonal diversity within another two populations of the species were analyzed. The genetic diversity was high (percentage of polymorphic bands, PPB = 90.0%; Shannon's information index, I = 0.383 ± 0.234) at the species level, but low within individual study populations (PPB = 35.8%; Shannon's information index I = 0.165 ± 0.241). The mean coefficient of gene differentiation (Gst) was 0.570, indicating that 43.0% of the genetic diversity resided within the population. Analysis of molecular variance (AMOVA) indicated that 50.47% of the genetic diversity among the study populations was attributed to geographical location while 12.3% was attributed to differences in their habitats. An overall value of mean estimated number of gene flow (Nm = 0.377) indicated that there was limited gene flow among the sampled populations. The level of clonal diversity found within the populations was considerably high (Simpson's diversity index, D = 0.985) indicating that clonal diversity contributes to a major extent to the overall genetic variation in the genetic structure of N. nucifera. On the basis of the high Gst and D values detected in this study we recommend that any future conservation plans for this species should be specifically designed to include those representative populations with the highest genetic variation for both in situ conservation and germplasm collection expeditions.  相似文献   

16.
The genetic diversity among five populations (Bhadbada reservoir, Mohinisagar reservoir, Bansagar reservoir, Bargi reservoir and Gandhisagar reservoir) was revealed using random amplified polymorphic DNA markers. 10 random primers screened, 5 primers revealed various banding patterns and yielded 71 total loci as an average of which 39.60 (55.77%) were polymorphic between the population and 86.84% within the population of Sperata seenghala. Population wise the highest genetic polymorphism was obtained in Bhadbada reservoir as 67.61% whereas the lowest was in Gandhisagar reservoir as 49.30%. However, Analysis of Molecular Variance indicated low genetic diversity (Hpop = 0.0921 ± 0.1249; I = 0.1584 ± 0.1942) in Bansagar reservoir. Relative genetic differentiation (GST = 0.3993) and restricted gene flow (Nm = 0.7523) as an average indicated low gene diversity among the fish populations. The un-weighted pair group method with averages (UPGMA) dendrogram showed 05 major clusters, each cluster representing a population. Fish population of Mohinisagar reservoir showed high genetic distance (0.3981) with respective Bargi reservoir population and highest genetic identity (0.8846) reflected between Bansagar and Gandhisagar reservoir. Highest genetic distance between Mohinisagar and Bargi reservoir fish populations shows no significant correlation between genetic and geographical distance of the genotypes collected from different lentic and geographical isolated water bodies. This investigation indicated that lowest genetic diversity existed in different geographic populations of S. seenghala. All the five populations were found to be low in genetic variation, which is useful information for future conservation measures of S. seenghala confined in natural water bodies of Madhya Pradesh.  相似文献   

17.
Prince Rupprecht's Larch (Larix principis-rupprechtii Mayr.) is one of dominant components of middle and high elevation forests in North China. Shanxi Province is well known as “the Hometown of Prince Rupprecht's Larch” in China. In this study, six natural populations of this species across Shanxi were selected to investigate the genetic variation of the species using amplified fragment length polymorphism (AFLP) markers. Results showed that in comparison with some other species of Larix, higher genetic diversity was revealed at the species level for L. principis-rupprechtii (percentage of polymorphic loci PPL = 71.9%, Nei's gene diversity HE = 0.225, Shannon information index I = 0.341). Most of genetic variation existed within populations (80.5%), while the genetic differentiation among populations was significant (p < 0.001) and higher (Gst = 0.194) than most other species of Larix. The differentiation can be attributed to the limited gene flow (Nm = 1.035) among populations, which could be due to the spatial isolation and habitat fragmentation. The six populations can be divided into three groups based on the Nei's genetic distances between populations (from 0.033 to 0.076). There was no significant correlation (r = 0.268, p > 0.05) between genetic distance and geographic distance among populations. The measures for in-situ or ex-situ conservation should be taken to preserve the genetic diversity of this species.  相似文献   

18.
Tapiscia sinensis is a Tertiary relict and endangered tree species with unique scientific research value and great economic value. In this study, we assessed the genetic diversity of five wild T. sinensis populations from different geographical regions using 10 polymorphic simple sequence repeat (SSR) markers. Our results reveal that the natural populations of T. sinensis have rich genetic diversity (PPL = 100%, He = 0.6904, I = 1.4368), with Shannon's index indicating that the T. sinensis populations are at a relatively stable stage. Of the genetic relationships among populations, the distance between the Hunan Yanling (YL) and Guizhou Xifeng (XF) populations is the smallest (0.4829); the genetic distance between the Shaanxi Ningshan (NS) and the Guizhou Xifeng (XF) populations is the largest (0.9821). A Mantel test shows that there is no correlation among the populations between geographic distance and genetic distance. AMOVA suggest that 33.3% of the genetic variation arose among the populations, while 66.7% of the variation arose within them. The moderate gene flow among populations (Nm = 0.7274) is not sufficient to counteract genetic drift within the populations and result in significant differentiation (Fst = 0.2987). Our results will benefit the conservation and exploitation of T. sinensis and provide a theoretical basis for further study of the evolution and phylogeography of the species.  相似文献   

19.
ISSR analysis was used to investigate genetic variations of 184 haploid and diploid samples from nine North Atlantic Chondrus crispus Stackhouse populations and one outgroup Yellow Sea Chondrus ocellatus Holmes population. Twenty-two of 50 primers were selected and 163 loci were scored for genetic diversity analysis. Genetic diversity varied among populations, percentage of polymorphic bands (PPB) ranged from 27.0 to 55.8%, H (Nei's genetic diversity) ranged from 0.11 to 0.20 and I (Shannon's information index) ranged from 0.16 to 0.30. Estimators PPB, H and I had similar values in intra-population genetic diversity, regardless of calculation methods. Analysis of molecular variance (AMOVA) apportioned inter-population and intra-population variations for C. crispus, showing more genetic variance (56.5%) occurred in intra-population, and 43.5% variation among nine populations. The Mantel test suggested that genetic differentiation between nine C. crispus populations was closely related with geographic distances (R = 0.78, P = 0.002). Results suggest that, on larger distance scale (ca. >1000 km), ISSR analysis is useful for determining genetic differentiations of C. crispus populations including morphologically inseparable haploid and diploid individuals.  相似文献   

20.
Black locust (Robinia pseudoacacia L.) is one of the important biomass sources used to produce bioenergy and bioethanol. In this study, we examined variations in chemical composition as well as genetic diversity and differentiation among 165 black locust plants from seven populations in five provinces (Beijing, Hebei, Gansu, Shanxi, Shandong) of Northern China using microsatellite markers(SSR). The contents of cellulose, hemicellulose, lignin varied widely among seven populations. Of the microsatellite markers analysed, 14 showed polymorphisms, and 45 alleles were identified. The polymorphism information content (PIC) ranged from 0.2885 (Rops4) to 0.6837 (Rp200), and most of the microsatellite loci had PIC values > 0.5. Expected heterozygosity (He), observed heterozygosity (Ho), and Shannon's information index (I) detected relatively high genetic variation among populations. The percentage of polymorphic loci in three populations was 100%, and the average among all populations were 95.92%. Analysis of molecular variance (AMOVA) indicated that the degree of genetic differentiation among the seven populations was low (GST = 0.058; Nm = 4.05), and chemical compositions had no relationship with genetic or geographic distance. This study demonstrates that microsatellite markers efficiently assess of genetic diversity and genetic differentiation in black locust populations, and all seven populations exhibit high genetic diversity. The population from Feixian has the potential to be lingo-cellulosic biomass for bioenergy and bioethanol.  相似文献   

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