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1.
Bakhtiarian savory (Satureja bachtiarica Bunge) is an endemic herb growing wild in Iran with interesting pharmacological and biological properties. In this research, the variability of essential oil content and phytochemical compositions among seven populations of this species was studied in both natural and field conditions. There was a wide interpopulation variability in phytochemical variation of studied populations under both natural and field conditions, indicating the existence of different chemotypes. Six chemical compositions showed high value in studied plants so that carvacrol and thymol were known as major compounds and confirmed by principal component analysis. Ilam population had the highest thymol in both field (77.10 %) and natural (42.32 %) conditions and was known as a thymol chemotype. Beside, Yazd and Shahrekord populations, respectively, showed the highest carvacrol percentages in both field (84.83 and 63.81 %) and natural (72.50 and 58.05 %) conditions and were known as carvacrol chemotypes. In other populations, carvacrol and thymol were the main components and showed partly equal percentage and these populations were known as carvacrol/thymol chemotypes. According to Pearson correlation analysis, carvacrol was negatively correlated with p-cymene, γ-terpinene and thymol (r = ?0.61, ?0.70 and ?0.98, respectively), indicating very high reverse correlation between carvacrol and thymol. In conclusion, the high value of the essential oil compositions in studied S. bachtiarica populations could provide useful information for conservation and selection of cross parents in breeding programs to develop improved cultivars.  相似文献   

2.
Ackee (Blighia sapida) is a native multipurpose species important for the livelihoods of the rural populations in Benin. Trees are found in natural forests or are managed by farmers in different traditional agroforestry systems. Genetic variation at amplified fragment length polymorphism (AFLP) markers, four nuclear microsatellites (nSSRs) and one chloroplast microsatellite (cpSSR) were investigated in 279 individuals from six wild and eight cultivated populations from Benin. The AFLP data revealed moderate levels of diversity of ackee in Benin (mean diversity values are proportion of polymorphic loci = 52.8% and Nei??s gene diversity = 0.157, for 375 AFLP fragments). The mean diversity values based on nSSR-markers are expected heterozygosity = 0.286, allelic richness = 2.77. Genetic variation of wild and cultivated populations did not differ markedly. AMOVA revealed that only 7.3 and 5.2% of the variation was partitioned among populations for nSSR- and AFLP-markers, respectively. A Mantel test based on these both marker-types revealed significant correlations between population pairwise geographic distance and genetic differentiation. Differentiation among cultivated populations was higher than among wild populations. The only polymorphic chloroplast microsatellite marker (ccmp7) showed three haplotypes. Cultivated populations from northeastern Benin were fixed on one haplotype which was not observed elsewhere indicating a different origin of these populations possibly from neighboring Nigeria. Farmer-led domestication had an impact on the spatial distribution of genetic variation but did not result in significant losses of diversity within populations. Measures to conserve genetic resources of ackee in each of the three main bioclimatic zones in Benin are proposed.  相似文献   

3.
Limonium sinense is a halobiotic herb endemic to China that has been traditionally used for hundreds of years for its good restorative function. Genetic variation and population structure of this species were investigated by using amplified fragment length polymorphisms (AFLPs) and inter simple sequence repeats (ISSRs). A high level of genetic diversity was detected [AFLP: H E = 0.284, percentage of polymorphic loci (PPL) = 92.68 %; ISSR: H E = 0.257, PPL = 85.71 %] at the species level with POPGENE. Based on analysis of molecular variation (AMOVA), the among-population component accounted for 29.03 % (AFLP) and 28.81 % (ISSR) of the genetic variation, indicating that most of the genetic variation was between individuals within populations. The Shannon diversity index (I) was higher for AFLP (0.432) than for ISSR (0.395). Five main clusters were shown in the unweighted pair-group method with arithmetic mean (UPGMA) dendrogram created using TFPGA, consistent with the result of principal coordinate analysis using NTSYS. In situ conservation is advocated first. Keeping a stable environment for this halobiotic herb is necessary. For ex situ conservation, it is important to establish a germplasm bank. AFLP and ISSR markers were proved to be efficient tools in assessing the genetic variation among populations of L. sinense. The patterns of variation appeared to be consistent for these two marker systems, and they can be used for management of genetic structure, protection of the halobiotic plant, and conservation of germplasm.  相似文献   

4.
Primula apennina Widmer is endemic to the North Apennines (Italy). ISSR were used to detect the genetic diversity within and among six populations representative of the species distribution range. High levels of genetic diversity were revealed both at population percentage of polymorphic band (PPB = 75.92%, H S = 0.204, H pop = 0.319) and at species level (PPB = 96.95%, H T = 0.242, H sp = 0.381). Nei gene diversity statistics (15.7%), Shannon diversity index (16.3%) and AMOVA (14%) detected a moderate level of interpopulation diversity. Principal coordinate and Bayesian analyses clustered the populations in three major groups along a geographic gradient. The correlation between genetic and geographic distances was positive (Mantel test, r = 0.232). All together, these analyses revealed a weak but significant spatial genetic structure in P. apennina, with gene flow acting as a homogenizing force that prevents a stronger differentiation of populations. Conservation measures are suggested based on the observed pattern of genetic variability.  相似文献   

5.
Isoetes hypsophila Hand.-Mazz. (Isoetaceae) is an endangered quillwort endemic to the Qinghai-Tibetan Plateau. Genetic variation and population structure of 12 I. hypsophila populations were examined by using amplified fragment length polymorphism (AFLP) markers. Eight primer pairs produced a total of 472 unambiguous bands, of which 229 (48.5%) were polymorphic. Intra-population genetic variation of Isoetes hypsophila was low (P P = 14.9%, H E = 0.039, hs = 0.084 and I = 0.061). The F statistics calculated by different approaches consistently revealed high genetic differentiation among populations, contributing approximately 50% of total gene diversity. Four genetic groups corresponding to four geographic regions were detected, indicating significant geographic structure. Our results suggest that both ongoing evolutionary forces (e.g., inbreeding system, bottlenecks resulting from fluctuation of water level) and historical events (e.g., orogenic movements which reduce gene flow among populations, repeated population retreat, and recolonization during ice ages) may have contributed to the genetic structure of I. hypsophila. In conservation, attention should be paid to preserving every population, and intra-region translocations can currently be recommended.  相似文献   

6.
Translocation is a strategy commonly used to maximize the persistence of threatened species, but it may sometimes lead to undesirable genetic consequences. The northern quoll (Dasyurus hallucatus) is a carnivorous marsupial that is critically endangered in Australia’s Northern Territory due to rapid population declines in areas recently colonized by the exotic cane toad Chaunus [Bufo] marinus. In 2003, 64 quolls were translocated to two offshore islands to establish insurance populations and reduce the species’ risk of extinction. In this study, we assessed genetic diversity at five microsatellite loci in the translocated populations, two endemic islands and three mainland populations. In the short-term (three generations), the translocated populations showed a slight but non-significant reduction in genetic diversity (A = 4.1–4.2; H e = 0.56–0.59) compared to the mainland source populations (A = 5.0–8.4; H e = 0.56–0.71). In comparison, high genetic erosion was observed in the endemic island populations (A = 1.5–2.9; H e = 0.11–0.34). Genetic bottlenecks were detected on both endemic islands and in one mainland population, indicating recent reductions in population size. Our results are consistent with previous studies describing greater losses of genetic diversity on islands compared to mainland populations. Divergence from ancestral allele frequencies in the translocated populations also suggests effects due to founder events. This study, although short-term, highlights the importance of continued monitoring for detecting changes in genetic diversity over time and makes a significant contribution to our understanding of the effects of founder events on island populations.  相似文献   

7.
Common thyme (Thymus vulgaris L.) is a Mediterranean evergreen shrub of the Lamiaceae that shows chemical polymorphism in its natural populations. In Mediterranean habitats six basic chemotypes have been described according to the main component in its essential oil: thymol, carvacrol, linalool, geraniol, α-terpineol, thuyanol-4, of which the thymol chemotype is widely used in cultivation and as a spice. In this study ten selected clones were analysed in terms of chemical composition of the volatile oil and genetic fingerprint. The study question was whether individual chemotypes can be distinguished by molecular markers. Chemical composition was analysed by GC-MS, and for assessing the genetic polymorphism ISSR marker system was chosen as it is reliable and easy to use even in case of less studied species. The studied T. vulgaris clones represented five different chemotypes and could be distinguished using 12 ISSR primers. Clones belonging to the thymol chemotype showed the most distinct separation. The study shows the potential of using molecular markers in breeding and selection of T. vulgaris, being able to differentiate different chemotypes.  相似文献   

8.
Allozyme diversity and population genetic structure studies were conducted in populations of two Mexican cycad species occurring in adjacent and closely related biogeographic regions. We evaluated if rarity traits in Dioon caputoi, a micro-endemic species, and Dioon merolae, a regional endemic with a wider distribution, influence levels of genetic diversity in different ways. We also explored if genetic structure differs in these species, considering that they have similar population histories. Our results indicate that D. caputoi harbors lower levels of genetic diversity and allelic richness (H E = 0.358, P = 76.9, A r = 1.86) than D. merolae (H E = 0.446, P = 92.3, A r = 2). However, genetic structure does not differ between the two species despite their contrasting geographic distributions (F ST = 0.06 vs. 0.07; D. caputoi and D. merolae, respectively). The comparison of population genetic structure information with historical and geographical aspects of the populations suggests that the rarity of D. caputoi might be due to relatively recent local ecological factors.  相似文献   

9.
Type of reproduction has an important effect on the maintenance of particular populations and species persistence in time and space. This trait significantly influences the ecological and genetic structure of populations, and in consequence the evolution of species. The primary objectives of this study were: to estimate genetic diversity within and among populations of clonal species Goodyera repens from different populations in northeastern Poland, and to amount factors shaping the genetic structure of this orchid. Based on 451 rosettes of G. repens from 11 localities in northeastern Poland, we conducted a genetic population analysis using allozymes. We included information on population size, flowering, fruit set and seed dispersal to elucidate their influences on genetic diversity of this species. Populations differed according to demographic properties. The majority of seeds (86.4–94.8 %) were found at a distance of 0.2 m. We observed a high level of genetic (P PL = 50 %, A = 1.68, H O = 0.210, H E = 0.204) and genotypic diversity (G = 163, G/N S = 0.66, G U = 30.2 %), and low but statistically significant genetic differentiation among populations (F ST = 0.060; P < 0.001). We suggest that the genetic diversity of G. repens is mainly an effect of the abundance of pine and spruce forest communities suitable for this species in NE Poland and the high level of sexual reproduction.  相似文献   

10.
Habitat loss, fragmentation of meadow patches, and global climate change (GCC) threaten plant communities of montane grasslands. We analyzed the genetic structure of the montane herb Geranium sylvaticum L. on a local scale in order to understand the effects of habitat fragmentation and potential GCC impacts on genetic diversity and differentiation. Amplified fragment length polymorphism (AFLP) fingerprinting and cpDNA sequencing was performed for 295 individuals of 15 G. sylvaticum populations spanning the entire distribution range of the species in the Taunus mountain range in Germany. We found patterns of substantial genetic differentiation among populations using 150 polymorphic AFLP markers (mean F ST = 0.105), but no variation in 896 bp of plastid DNA sequences. While populations in the center of their local distribution range were genetically diverse and less differentiated, higher F ST values and reduced genetic variability was revealed for the populations at the low-altitudinal distribution margins. Projections of GCC effects on the distribution of G. sylvaticum in 2050 showed that GCC will likely lead to the extinction of most edge populations. To maintain regional genetic diversity, conservation efforts should focus on the diverse high-altitude populations, although a potential loss of unique variations in genetically differentiated peripheral populations could lower the overall genetic diversity and potentially the long-term viability in the study region. This study documents the usefulness of fine-scale assessments of genetic population structure in combination with niche modeling to reveal priority regions for the effective long-term conservation of populations and their genetic variation under climate change.  相似文献   

11.
Thymus caespititius Brot. is an important aromatic species, due to synthesis and production of essential oils for the pharmaceutical and food industries. In the present study, levels of essential oils from two chemotypes, including carvacrol/thymol (CT) and sabinene/carvacrol (SC), were evaluated in proliferating shoot cultures (6–12 subcultures following establishment) and compared to those from field-grown plants. The essential oils were isolated by hydrodistillation and analysed by gas chromatography (GC) and GC–mass spectrometry (GC–MS). Cultures grown under in vitro culture conditions, evaluated over six subcultures, were found to maintain stable composition of essential oils. For the CT chemotype, carvacrol (42 %) and thymol (23 %) were the main essential oil components detected in field-grown plants; in proliferating shoot cultures the levels detected attained 17–25 % in the case of carvacrol and 18–23 % in that of thymol, closely followed by carvacryl acetate (15–23 %) and thymyl acetate (11–15 %). For the SC chemotype, carvacrol (13–28 %), sabinene (18–45 %), and thymol (9–12 %) were the main essential oil components detected in both field-grown and proliferating shoot cultures. Our experiments showed that the essential oil composition in proliferating shoot cultures was not only stable, but also qualitatively similar to that of field-grown plants, notwithstanding minor quantitative differences.  相似文献   

12.
The genus Opisthopappus consists of two species, O. longilobus and O. taihangensis. Both of them are important economic and ornamental plants but endangered in China. In this study, genetic variation in four populations of O. longilobus and nine populations of O. taihangensis was estimated by chloroplast microsatellites (cpSSR). Low genetic diversity was detected in O. longilobus and O. taihangensis populations. The percentages of polymorphic loci (PPL), Nei’s gene diversities (h), and Shannon’s indices (I) was 53.56 %, 0.074, and 0.139, respectively, for O. longilobus, while PPL = 44.44 %, h = 0.018, I = 0.048 for O. taihangensis. Thirteen chloroplast haplotypes were identified from 153 individuals analyzed of two species. Ten haplotypes were found in O. longilobus, while seven in O. taihangensis. Haplotype 1 was the common and ancestral one. The level of haplotype diversity was also low (Hd O. longilobus  = 0.4875, Hd O. taihangensis  = 0.3452). AMOVA analysis revealed that the majority of the genetic differences was partitioned within populations of O. longilobus and O. taihangensis, as confirmed by PCoA and cluster analysis. Inter-population genetic distances among population of O. longilobus and O. taihangensis correlated insignificantly with geographic distances (r = 0.286, P = 0.128 for O. longilobus vs. r = 0.356, P = 0.058 for O. taihangensis). The self-compatibility, effective gene flow, narrow geographical distribution, and historical factors may be the main factors causing differentiation in the genetic structure of O. longilobus and O. taihangensis populations.  相似文献   

13.
Coscinium fenestratum is a critically endangered medicinal plant, well-known for its bioactive isoquinoline alkaloid berberine. The species has been over harvested from its natural habitats to meet the huge requirement of raw drug market and industrial consumption. This has lead to a rapid decline in the population size and has also led to local population extinction at few locations in the Western Ghats, India. In this study, inter-simple sequence repeat markers were used to investigate the genetic variation and population structure of seven extant populations of C. fenestratum from the central Western Ghats, India. Eight primer combination produced a total of 57 unambiguous bands, of which (47.1 %) were polymorphic. The species exhibited a moderate to low level of intra population genetic diversity (H s = 0.347 ± 0.008; H t = 0.378 ± 0.006 (POPGENE) and H s = 0.262 ± 0.0028; H t = 0.204 ± 0.020 (HICKORY)). The populations were low to moderately differentiated from one another (G ST = 0.221) and geographical distance was not significantly correlated with genetic distance, suggesting that these long-lived, geographically distant remnant populations were once connected through gene flow. There was a significant amount of genetic variation among populations (19.85 %). The Bayesian software STRUCTURE and HICKORY were used to further reveal the genetic structure of C. fenestratum. The results revealed weak population structure (K = 2) with one single widespread gene pool, and indicated that gene flow and inbreeding are likely to be the major driving force in shaping current population genetic structure of C. fenestratum. Thus, an understanding of the genetic diversity and population structure of C. fenestratum can provide insight into the conservation and management of this species.  相似文献   

14.
Small or isolated populations are highly susceptible to stochastic events. They are prone and vulnerable to random demographic or environmental fluctuations that could lead to extinction due to the loss of alleles through genetic drift and increased inbreeding. We studied Ambystoma leorae an endemic and critically threatened species. We analyzed the genetic diversity and structure, effective population size, presence of bottlenecks and inbreeding coefficient of 96 individuals based on nine microsatellite loci. We found high levels of genetic diversity expressed as heterozygosity (Ho = 0.804, He = 0.613, He* = 0.626 and HNei = 0.622). The population presents few alleles (4–9 per locus) and genotypes (3–14 per locus) compared with other mole salamanders species. We identified three genetically differentiated subpopulations with a significant level of genetic structure (FST = 0.021, RST = 0.044 y Dest = 0.010, 95 % CI). We also detected a reduction signal in population size and evidence of a genetic bottleneck (M = 0.367). The effective population size is small (Ne = 45.2), but similar to another mole salamanders with restricted distributions or with recently fragmented habitat. The inbreeding coefficient levels detected are low (FIS = ?0.619–0.102) as is gene flow. Despite, high levels of genetic diversity A. leorae is critically endangered because it is a small isolated population.  相似文献   

15.
Tricyrtis ishiiana is a relic endemic plant taxon of the Convallariaceae that inhabits two nearby gorges in Kanagawa Prefecture, Japan. The distribution range and number of populations are thought to have been reduced to the present refugial populations during the Quaternary climatic oscillations. Because of its showy flowers, this plant has faced illegal removal from its natural habitats for horticultural use and has been designated a critically endangered species (class IA). In this study, we analyzed the genetic structure of the relict populations of T. ishiiana in order to contribute to the conservation strategies of the prefectural government. Our analyses of nine nuclear microsatellite loci detected high genetic diversity (H E = 0.704 and H O = 0.541) for the two populations. The two populations were slightly differentiated (R ST = 0.032), accompanied by faint substructure across the populations (K = 3). In addition, each population exhibited spatial genetic structuring. The relatively low inbreeding coefficient for both populations together (F IS = 0.233) and each population separately (F IS = 0.217?C0.246) may be attributable to crossing among descendants within a population along with occasional gene flow between the populations. These results suggested that the extant populations have not experienced a severe bottleneck. The two extant populations were genetically differentiated at a very low level, accompanied by occasional pollen flow via pollinators and/or seed dispersal by gravity in the mountainous environment. Occasional gene exchange between the populations has allowed T. ishiiana to harbor high genetic diversity despite being a relic plant confined to two small refugial populations.  相似文献   

16.
Currently, many Brazilian orchids are threatened with extinction resulting from habitat loss and intense harvesting pressure stemming from their value as ornamental plants. Therefore, the genetic diversity in remaining populations is fundamental to the survival of these species in natural environments. In order to inform conservation strategies, this study evaluated the genetic diversity and structure of Cattleya granulosa populations. The sample consisted of 151 individuals from 12 populations in the Atlantic Forest, northeastern Brazil, evaluated using 91 ISSR markers. Genetic variability was assessed through molecular variance, diversity indexes, clusters of genotypes through Bayesian analysis, and tests for genetic bottlenecks. From all polymorphic loci, genetic diversity (HE) varied between 0.210 and 0.321 and the Shannon index ranged from 0.323 and 0.472. Significant genetic differentiation between populations (ΦST = 0.391; P < 0.0001) resulted in the division of the populations into five groups based on the log-likelihood Bayesian analysis. We found significant positive correlation between geographical and genetic distances between populations (r = 0.794; P = 0.017), indicating isolation by distance. Patterns of allelic diversity within populations suggest the occurrence of bottlenecks in most C. granulosa populations (n = 8). Therefore, in order to maintain the genetic diversity of the species, the conservation of spatially distant groups is necessary.  相似文献   

17.
Saruma henryi Oliv., the only representative of the monotypic genus Saruma Oliv. (Aristolochiaceae), is an endangered perennial herb endemic to China. It is a phylogenetically, ecologically, and medicinally important species. In the present study, inter-simple sequence repeat (ISSR) markers were employed to investigate the genetic diversity and differentiation of 14 populations. A total of 16 selected primers yielded 175 bright and discernible bands, with an average of 10.94 per primer. POPGENE analysis showed that the genetic diversity was quite low at the population level (h = 0.0447–0.1243; I = 0.0642–0.1853; PPB = 10.29–36.57%), but pretty high at the species level (h = 0.2603; I = 0.3857; PPB = 73.71%). The hierarchical analysis of molecular variance (AMOVA) revealed a high level of genetic differentiation among populations (67.18% of total variance components, P < 0.001), in line with the gene differentiation coefficient (G ST = 0.6903) and the limited among-population gene flow (N m = 0.2243). Both Principal Coordinates Analysis (PCoA) and UPGMA cluster analysis supported the grouping of all 14 populations into three geographic groups, among which there occurred a moderate level of genetic differentiation (33.18% of total variance components, P < 0.001) as shown by AMOVA analysis. In addition, Mantel test revealed a significant correlation between genetic and geographic distances among populations (r = 0.7792, P = 0.001), indicating the role of geographic isolation in shaping its present population genetic structure. The present levels and patterns of genetic diversity of S. henryi were assumed to result largely from its breeding system, geographic isolation, clonal growth, its unique biological traits and evolutionary history. The high genetic differentiation among populations implies that the conservation efforts should aim to preserve all the extant populations of this endangered herb.  相似文献   

18.
Gossypium mustelinum is a wild cotton relative found only in the semiarid region of Bahia state in Brazil, and changes caused by humans in the natural habitat of this species have endangered the existence of several natural populations. Information about the occurrence and genetic composition of these populations is necessary to design effective conservation measures. The aim of this study was to characterize the in situ maintenance mode and assess the genetic diversity of G. mustelinum populations in the basin of the De Contas River. A sample of 205 G. mustelinum specimens was collected from the margins of the Jacaré, Riacho Quixaba, Riacho Serra Azul, and Riacho Riachão rivers and genotyped using 13 SSR primer pairs. In general, all G. mustelinum populations exhibit inadequate in situ maintenance, predominantly due to the deforestation of riparian vegetation and herbivory. The observed total genetic diversity of G. mustelinum was significant (H E = 0.489), highly structured (F ST = 0.534), and organized in homozygous genotypes (F IS = 0.873). The high observed inbreeding level is consistent with the predominance of self-fertilization and geitonogamy (t m = 0.234). In addition, the pattern of genetic structure tended to form groups that coincided with the collection sites, i.e., first clustering within subpopulations, then within populations, and finally within the closest populations. Thus, the observed genetic diversity is likely to be rapidly lost, and conservation measures should therefore be undertaken.  相似文献   

19.
20.
The Korean black scraper, Thamnaconus modestus, is one of the most economically important maricultural fish species in Korea. However, the annual catch of this fish has been continuously declining over the past several decades. In this study, the genetic diversity and relationships among four wild populations and two hatchery stocks of Korean black scraper were assessed based on 16 microsatellite (MS) markers. A total of 319 different alleles were detected over all loci with an average of 19.94 alleles per locus. The hatchery stocks [mean number of alleles (N A) = 12, allelic richness (A R) = 12, expected heterozygosity (He) = 0.834] showed a slight reduction (P > 0.05) in genetic variability in comparison with wild populations (mean N A = 13.86, A R = 12.35, He = 0.844), suggesting a sufficient level of genetic variation in the hatchery populations. Similarly low levels of inbreeding and significant Hardy–Weinberg equilibrium deviations were detected in both wild and hatchery populations. The genetic subdivision among all six populations was low but significant (overall F ST = 0.008, P < 0.01). Pairwise F ST, a phylogenetic tree, and multidimensional scaling analysis suggested the existence of three geographically structured populations based on different sea basin origins, although the isolation-by-distance model was rejected. This result was corroborated by an analysis of molecular variance. This genetic differentiation may result from the co-effects of various factors, such as historical dispersal, local environment and ocean currents. These three geographical groups can be considered as independent management units. Our results show that MS markers may be suitable not only for the genetic monitoring of hatchery stocks but also for revealing the population structure of Korean black scraper populations. These results will provide critical information for breeding programs, the management of cultured stocks and the conservation of this species.  相似文献   

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