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1.
In this study, the genetic diversity and differentiation of 10 natural Prunus pseudocerasus Lindl. populations were investigated using inter-simple sequence repeat (ISSR) markers. Totally, 18 selected primers generated 150 loci, with an average of 8.33 bands per primer. The results showed that the percentage of polymorphic bands (PPB) was pretty low at the population level (PPB = 1.13–32%), but relatively high at the species level (PPB = 84%). Besides, a high level of genetic differentiation among populations was detected based on the gene differentiation coefficient (G ST = 0.7118) and the hierarchical analysis of molecular variance (AMOVA) (Φ ST = 64.53%, P < 0.001), in line with the low inter-population gene flow (N m = 0.2025). Moreover, Mantel test revealed a significant correlation between genetic and geographic distances among the populations (r = 0.5272, P < 0.005). The high level of intraspecific genetic diversity was probably related with its life history traits, while its small population size and the resultant high levels of genetic drift and inbreeding might explain the low genetic diversity within populations. The relatively high inter-population genetic differentiation was largely attributed to its small population size, habitat fragmentation, the mode of pollen and seed dispersal, and geographic isolation. Based on the present study, conservation strategies were proposed to preserve this valuable natural germplasm resource.  相似文献   

2.
Genetic variation of wild populations and cultivars of Luohanguo (Siraitia grosvenorii), a plant species endemic to southern China, was assessed using random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) markers. Based on the results for 130 individuals from seven populations, a high level of genetic diversity of Luohanguo was observed at the species level. The percentage of polymorphic loci (P) was 89.4%, Nei’s gene diversity (H e) was 0.239, and Shannon’s information index (H o) was 0.373 based on the combined AFLP and RAPD data. There was a high degree of genetic differentiation, with 45.1% of the genetic variation attributed to differences between the populations. The genetic diversity of the Luohanguo cultivars is much lower than that of wild populations (P = 41.8%, H e = 0.141, H o = 0.211), and a distinct genetic differentiation is observed between the cultivars and wild accessions. The pool of genetic variation in the wild populations provides an excellent gene resource for Luohanguo breeding.  相似文献   

3.
Orychophragmus violaceus, a ground covering plant that is widely distributed in China. It has both high economical value in food, forage, health care and ornamental value in gardening. In this study, the genetic diversity of 245 individuals from nine populations in China were investigated using the inter-simple sequence repeat markers. Of the 100 primers screened, eight were highly polymorphic. Using these primers, 162 discernible DNA fragments were generated with 150 (92.59%) being polymorphic, indicating a pronounced genetic variation at the species level. Also, there were high levels of polymorphism at the population level with the percentage of polymorphic bands ranging from 85.74 to 90.06%. Analysis of molecular variance showed that the genetic variation within populations was 80.80% and the variance among populations was 16.43%. The Nei’s G ST (0.1643) and gene flow among populations (Nm = 2.5760) revealed large gene exchanges among populations. O. violaceus belongs to out-crossing plants. It is capable of reproducing by self-sowing, thus can influence population genetic structure. The pronounced genetic variation within populations tells us that O. violaceus is a proper plant for genetic research and that there is great potential of breeding this species for gardening.  相似文献   

4.
There is a need to understand whether weed genetic diversity is the same among different populations, especially between those exposed to herbicide selection and other without exposure history. Inter-simple sequence repeat (ISSR) were used to assess level and patterns of genetic diversity in wild Brassica juncea (L.) Czern. et Coss. populations. A total of 93 plants from 24 wild populations in China were analysed by eight primers resulting in 86 highly reproducible ISSR bands. The analysis of molecular variance (AMOVA) with distances among individuals corrected for the dominant nature of ISSRs showed that most of the variation (54.09%) occurred among populations, and the remaining 45.91% variance was attributed to differences among individuals within populations. The high differentiation was, perhaps, due to limited gene flow (Nm < 1.0) of this species. Though highest gene diversity was observed in resistant B. juncea population, the overall distribution of diversity across China was not geographic dependent. High F ST value (0.541) corroborated AMOVA partitioning and provided significant evidence for population differentiation in wild B. juncea. UPGMA cluster analyses, based on Nei’s genetic distance, revealed grouping pattern geographically. Based on these results, the factors affect weed population genetic diversity and implication for herbicide resistance evolution were discussed in the context of transgenic crops advent and increasing herbicide usage in China.  相似文献   

5.
To study the magnitude and nature of genetic variation in E. fibrosus, the levels and distribution of allozyme and RAPD variations were investigated in populations collected from Finland and Russia. The results obtained from the allozyme and RAPD studies were compared to each other in 10 of the populations. The allozyme analysis showed that 6 of 12 presumed loci (50%) were polymorphic within the species, while the mean number of polymorphic loci within populations was 4.8%. The mean number of allele per locus for the species was 1.5 and 1.05 across the populations. Genetic diversity at the species level was low (H es = 0.025), and the mean population genetic diversity was even lower (H ep = 0.007). Both these values were much lower than the average for other Elymus and self-fertilising species. The largest proportion of the total allozyme diversity was found among, rather than within the populations (G ST = 0.70). The allozyme genetic distances between the populations did not reflect geographic distances. Cluster and principal coordinates analyses revealed the same allozyme relationship patterns among the populations. A comparison of allozyme and RAPD variation in 10 of the populations showed differences in the amount of genetic variation. The RAPD analysis revealed higher levels of variation (A p = 1.19, P p = 20.3 and H ep = 0.09) than the allozyme one) A p = 1.06, P p = 5.8 and H ep = 0.008). For both markers, the largest proportion of the total gene diversity was found among the populations studied (G st = 0.63 for RAPDs and G st = 0.65 for allozyme). In contrast to the allozyme analysis, the RAPD based genetic distances did reflect geographic distances. The cluster and principal coordinates analyses showed different grouping of populations for each data set. There was a positive, but not significant, correlation (r = 0.41) between the genetic distance matrices resulting from these markers. Regional comparison revealed that the Finnish populations had a higher diversity than the Russian ones. Generally, this study indicates that E. fibrosus contains low genetic variation in its populations. The results are discussed in the context of conservation of the species.  相似文献   

6.
DNA sequences from the ITS region of the nuclear genome and Inter-Simple Sequence Repeat markers (ISSR) were used to estimate genetic diversity among and within populations of the Frankincense tree Boswellia sacra from Dhofar, Oman. This is a culturally and ecologically relevant species that is showing symptoms of decline due to anthropic factors and, possibly, global warming. ITS sequences were 511 bp long and showed low (6.4%) variation among geographically different populations. The four selected ISSR primers yielded 93 reproducible bands, of which 91 (97.9%) were polymorphic in the 97 individual profiles obtained. Total genetic diversity (H T) and average heterozygosity within populations (H S) resulted fairly low (0.22 and 0.136, respectively). The accession from Wadi Dowkah, an UNESCO world heritage site, showed the lowest level of genetic diversity (H E = 0.107), while the eastern populations from the Hasik area harboured a slightly greater amount of variation. Analysis of Molecular Variance showed that differentiation among populations was relatively high (38.1%), possibly due to the reduced gene flow between the largely isolated stands of Boswellia (N m = 0.39). Genetic distances and AMOVA suggested a clear differentiation between the eastern and western coastal populations, while those from the internal area did not form a consistent group. For conservation, the eastern sites should be given priority as core populations harbouring significant amounts of allelic diversity. Reasons for reinforcing the more depauperated stands, such as Wadi Dowkah, with local plant material only or, alternatively, with the introduction of germplasm from genetically distinct stands are discussed.  相似文献   

7.
Using the 8 specific primer pairs based on the conserved motifs of plant resistance genes, the plant disease resistance gene analog polymorphisms (RGAPs) in 15 wild emmer wheat (Triticum dicoccoides) populations from Israel had been detected. High genetic variations at the RGAP loci were observed in T. dicoccoides populations. A total of 254 discernible bands were obtained among 115 accessions, and 192 bands (75.6%) were polymorphic. Each genotype had a unique banding profile, and the genetic similarity coefficient ranged from 0.094 to 0.862. In T. dicoccoides, the proportion of polymorphic loci (P), the genetic diversity (He) and Shannon’s information index were 0.756, 0.362 and 0.541, respectively. The proportion of polymorphic loci (P) per population averaged 0.732 (range: 0.515–0.932); genetic diversity (He) averaged 0.271 (range: 0.212–0.338); and Shannon’s information index averaged 0.404 (range: 0.310–0.493). The coefficients of genetic distance (D) among populations averaged 0.107 (range: 0.043–0.178), and the results of Mantel test (r = 0.168, P = 0.091) showed that the estimates of genetic distance were geographically independent. Neighbor-joining cluster analysis suggested that the genetic relationships of T. dicoccoides populations were associated with their ecogeographic distribution. The hierarchical analysis of molecular variance (AMOVA) and the coefficient of gene differentiation (G ST ) values revealed that most of the variations were presented within populations, although significant differences among populations and regions were also detected. The values of P and Shannon’s information index were negatively correlated with the two factors: Tdd (day–night temperature difference) and Ev (mean annual evaporation), whereas they were positively correlated with one water factor: Rn (mean annual rainfall). The correlation matrix between He in the RGAPs and geographic variables contained 20 significant (P < 0.05) correlations. The present study established that T. dicoccoides in Israel had a considerable amount of genetic variations at RGAP loci at least partly correlated with ecological factors.  相似文献   

8.
Citrus hongheensis is a critically endangered species endemic to the Honghe river region in southeastern Yunnan, China. Its genetic diversity and differentiation were investigated using Inter-Simple Sequence Repeat (ISSR) markers. One hundred primers were screened, and a total of 245 loci were amplified from seven natural populations by 13 informative and reliable primers. Of these 245 ISSR loci, 233 were polymorphic and the detected variations revealed a relatively high level of intraspecific genetic diversity. At the population level, the mean percentage of polymorphic loci (PPB) was 36.50%, while the average expected heterozygosity (He) and Shannon diversity index (Ho) were 0.1327 and 0.1972, respectively. At the species level (across all populations), PPB was 95.10%, while He and Ho were 0.3520 and 0.5195, respectively. A high Gst value (0.6247) indicated that there is significant differentiation among populations, which was confirmed by AMOVA analysis (Φst = 0.6420). Pairwise genetic identity (I) values among populations ranged from 0.6341 to 0.7675, with a mean of 0.7008. We propose that the high level of genetic differentiation may be the result of habitat fragmentation and limited gene flow (Nm = 0.1502). For effective in situ conservation and population restoration of C. hongheensis it will be important to maintain historical processes, including high outbreeding rates, sufficient gene flow, and large effective population sizes.  相似文献   

9.
Panax ginseng C. A. Meyer is a medicinally important herb with a long history of cultivation, and includes three cultivated types, viz. garden ginseng (GGS), forest ginseng (FGS) and transplanted wild ginseng (TGS). In the present study, inter-simple sequence repeat (ISSR) markers were employed to investigate the genetic variability in 282 individuals, which corresponded to 16 cultivated ginseng populations. Genetic diversity was high at the species level (h = 0.2886; I = 0.4382; PPB = 98.96%), but relatively lower at the cultivated-type level (GGS: h = 0.2294, I = 0.3590, PPB = 85.42%; FGS: h = 0.1702, I = 0.2559, PPB = 57.29%; TGS: h = 0.2021, I = 0.3125, PPB = 76.04%). The hierarchical analysis of molecular variance (AMOVA) revealed pronounced genetic differentiation among populations (Φ ST = 53.94%), which was confirmed by the gene differentiation coefficient (G ST = 0.4910) and low gene flow (N m = 0.5184). Both Principal Coordinates Analysis (PCoA) and UPGMA cluster analysis supported the clustering of all 16 populations into three groups, corresponding to the three cultivated types, among which there occurred remarkable genetic differentiation (Φ ST = 37.43%). Pronounced genetic differentiation was also detected among populations within the three cultivated types (GGS: Φ ST = 40.83%, G ST = 0.3187, N m = 1.0691; FGS: Φ ST = 22.85%, G ST = 0.2328, N m = 1.6480; TGS: Φ ST = 30.68%, G ST = 0.2540, N m = 1.4686). Mantel test indicated no significant correlation between geographic and genetic distances at both species and cultivated-type levels (P > 0.05). These findings have profound implications for the sustainable utilization of this precious medicinal herb.  相似文献   

10.
Twenty landraces of cowpea (Vigna unguiculata (L.) Walp.) scattered throughout Algeria were compared through morphological and genetic characterization. At the morphological level, for qualitative characters there was no intra-landrace variation and for quantitative characters the variations were low except for landrace NAG2 Three different cultigroups were located in Algeria: Biflora that was dominant in the Sahara, Melanophtalmus in the North and Unguiculata including one landrace in Kabylia and two in Sahara. The AMOVA analysis indicated that the genetic variation was lower within than among agro-ecological regions. A Mantel test, revealed a correlation between the qualitative morphological data and the geographical data (R = 0.28; P < 0.01), indicating that the degree of morphological change among landraces was roughly proportional to the geographical distances separating them. Genetic diversity was analyzed by using 11 random amplified polymorphic DNA (RAPD) and 12 inter-simple sequence repeat (ISSR) markers. No intra-landrace variability was found. The eleven RAPD primers yielded 77 bands, of which 45 (58.44%) were polymorphic; the genetic similarity ranged from 66.0 to 96.7%. The twelve ISSR primers provided a total of 104 bands, of which 65 (62.5%) were polymorphic; the genetic similarity ranged from 62.8 to 97.8%. cluster analysis showed a good match between genetic background and geographical distribution, which was confirmed by the results of the Mantel test. In particular, geographical data and genetic data were found to be correlated: (R = 0.33; P < 0.01) for RAPD, (R = 0.37; P < 0.01) for ISSR, and (R = 0.33; P < 0.01) for a combined RAPD-ISSR dataset. Moreover, despite the absence of significant correlation between morphological and RAPD data (R = 0.14; P = 0.14), significant correlations between morphological data and both ISSR (R = 0.27, P < 0.05) and a combined RAPD-ISSR dataset (R = 0.22, P < 0.05) were noted. ISSR markers were better linked to morphological variation than were RAPD markers. However, despite this, genetic distances among these landraces were found to be essentially the same no matter which markers were used.  相似文献   

11.
Tetraena mongolica Maxim, is a critically endangered and endemic species of westem Inner Mongolia in China. Genetic variability within and among eight extant populations of this species was assessed using ISSR PCR (13 primers). We expected a low genetic diversity level, but our results revealed an intermediate level of intraspecific genetic diversity, probably resulting from this species being in a refuge during the last glaciation (at population level: P=48.1%, Ae=1.305, HE=0.177 and Hpop=0.264; at species level: P=63.3%, A=1.368, HT=0.213 and Hsp=0.324). A low level of genetic differentiation among populations was detected based on Nei's genetic diversity analysis (16.91%), Shannon's diversity index (18.83%) and AMOVA (15.2%). Populations shared high levels of genetic identity (I=0.9516±0.013). The extensive gene flow was a plausible reason for the low genetic differentiation.  相似文献   

12.
Eremostachys superba Royle ex Benth. (Lamiaceae) has undergone a severe decline in population size since its discovery in the North-western Himalayas in late 19th century. One hundred and seventy-two plants from six populations in the Indian states of Uttar Pradesh and Jammu & Kashmir, located between 0.45 km and 455.72 km apart from each other were evaluated for RAPD polymorphism. Sixteen random primers generated 92 bands overall, 77 of which were polymorphic. Shannon’s index of genetic diversity within populations (H o) ranged between 0.305 and 0.421; the average within-population diversity (H pop) was 0.389; and the total species diversity (H sp) was 0.478. The population from Mohand (representing the type locality) had the fewest plants, at 18, and was genetically the most depauperate. Among the other populations, ranging in size between 52 and 1,022 individuals, no relation between population size and genetic diversity was evident. It is suggested that these six populations represent relics of a larger, extended population, in which the presence of perennating rootstocks has helped preserve historic patterns of genetic diversity. AMOVA revealed that 83.01% of the variation exists within populations, which was consistent with earlier studies on the reproductive biology of E. superba, which indicated this species is predominantly allogamous. FST distances between all populations were significant, indicating geographic differentiation despite some of them being closely separated. Habitat restoration and protection from indiscriminate harvesting are proposed as primary strategies for conserving E. superba. Rejuvenation of the Mohand population through intrapopulation crossing between plants bearing diverse molecular phenotypes is also suggested.  相似文献   

13.
Genetic variation and its distribution within and among 23 populations of Triticum urartu collected from Syria, Lebanon, Turkey, Armenia, and Iran was estimated using isozyme markers at eight polymorphic loci. The number of alleles per locus (A= 1.21), percentage polymorphic loci (P= 20.1%), and mean gene diversity (He= 0.024) were relatively low. In a population from Lebanon, a high number of alleles per locus (A= 2.13) and percentage polymorphic loci (P= 87.5%) was found. On average, genetic variation among populations (GST= 0.407) was smaller than within-population variation (0.593). However, different patterns of genetic structure were found among various geographic regions. Interpopulation variation was highest for the Iranian populations (0.89) followed by the Turkish populations (0.66). A reverse pattern was observed for the Syrian (0.11) and for the Lebanese (0.13) populations. The Armenian populations exhibited similar interpopulation and within-population variation. Principal component and cluster analyses resulted in distinct grouping of the geographically proximal populations, with the exception of the two Iranian populations. The Turkish populations were different from the neighboring Armenian populations compared to other countries. The populations from southern Syria and those from Lebanon also exhibited a high degree of genetic diversity. The two most heterozygous loci, Mdh-2 and Pgi-2, separated the populations along the first and second principal components, respectively. Most of the rare alleles were scattered sporadically throughout the geographic regions. Rare alleles with high frequencies were found in the Turkish and Armenian populations. These results indicated that different geographic regions require specific sampling procedures in order to capture the range of genetic variation observed in T. urartu populations.  相似文献   

14.
Wild banana Musa balbisiana Colla is one of the progenitors of cultivated bananas and plantains. It is native to Southeast Asia and the western Pacific. South China represents the northern limit of its distribution range. The genetic diversity of Musa balbisiana was assessed by the amplified fragment length polymorphism (AFLP) fingerprinting in 15 populations of China. Four primer pairs produced 199 discernible loci. High levels of genetic diversity were detected, with P = 78.5%, H E = 0.241, and H pop = 0.3684 at population level, and P = 100%, H T = 0.3362 and H sp = 0.5048 at species level. Significant genetic differentiation among populations was detected based on Hickory’s analysis (27.6%), Shannon’s diversity index (27.0%) and AMOVA (27.1%). The AFLP results are discussed and compared with data obtained by microsatellites method. The estimates of genetic diversity and differentiation between each pair of populations computed with microsatellites and AFLP markers were not significantly correlated. Conservation strategies for Musa balbisiana in China are proposed.  相似文献   

15.
Genetic variability within and among eight landrace populations of tea (Camellia sinensis (L.) O. Kuntze) located in southern Kyoto, Japan, was surveyed with six microsatellite markers. The average number of alleles per locus was 3.83 to 4.67 for landrace populations, whereas the corresponding value among modern cultivars and breeding lines was 6.63. Expected heterozygosity values averaged over loci within landrace populations ranged from 0.498 to 0.723. A similar level of variation, 0.682, was observed for cultivars and breeding lines. High fixation index values (0.177–0.417) for each population are consistent with biparental inbreeding within the population. Genetic differentiation among local populations was extremely low with F ST = 0.062, although AMOVA revealed significant differentiation among landrace populations. We propose that these populations share a common ancestral gene pool and that some degree of artificial selection within each population has been performed by local farmers. Neighbor-joining analysis revealed that genetic relationships among populations reflect geographical location of populations. This might result from more frequent genetic exchange by nearby farmers.  相似文献   

16.
Genetic diversity of 70 populations of niger (Guizotia abyssinica) representing all its growing regions in Ethiopia was investigated using random amplified polymorphic DNA (RAPD) to reveal the extent of its populations genetic diversity. Ninety-seven percent of the loci studied was revealed to be polymorphic for the whole data set. The within population diversity estimated by Shannon diversity index and Nei gene diversity estimates was revealed to be 0.395 and 0.158, respectively. The extent of genetic variation of populations from major niger producing regions was significantly lower than that of populations from other regions; however, it is distributed regardless of altitude of growth. Genetic differentiation between populations was estimated with Shannon index as G′ ST (0.432), Nei’s G ST (0.242) and AMOVA based F ST (0.350) and appears to be equivalent to the average values calculated from various RAPD based studies on outcrossing species. Higher proportion of the variation detected by AMOVA resided within populations (64.58%) relative to the amount of variation among populations (35.42%). UPGMA cluster analysis showed that most of the populations were clustered according to their region of origin. However, some populations were genetically distant from the majority and seem to have unique genetic properties. It is concluded that the crop has a wide genetic basis that may be used for the improvement of the species through conventional breeding and/or marker assisted selection. Collection of germplasm from areas not yet covered and/or underrepresented is the opportunity to broaden the genetic basis of genebank collection.  相似文献   

17.
Allanblackia parviflora A. Chev. (Clusiaceae Lindley) is an indigenous tree species which is found in the rain forest regions of Ghana. It is a potential candidate fruit tree species being introduced in agroforestry systems. Information on genetic diversity, reproductive biology and fruit yield are not known. Field expeditions to seven populations of Allanblackia parviflora in Ghana were undertaken in 2003–2006 during which fruits were collected from 109 trees for characterization. The species was found to be dioecious. The colour of flowers varied from whitish to reddish. No ecological differences in number of fruits per tree, fruit shape and seed health were observed. However, large variations in fruit size and shape were observed among individual trees sampled. A high heritability (h 2 = 0.822) in fruit size and genetic gain (G = 20.1%) in fruit size for selection of trees with above average fruit size were observed. A positive significant correlation was observed between fruit size and seed weight (R = 0.54, P < 0.05; Fig. 6). The results suggest that selection and cloning of trees with large fruits could lead to higher yield of seeds for oil production.  相似文献   

18.
Myrtus communis L. (Myrtaceae), in Tunisia, is closely associated with Quercus suber L. forest which stretched continuously from the North to parts of Cap Bon and Tunisian Dorsal. The destruction of the primary oak forests associated to an over-exploitation of Myrtus for its essential oil quality had led to discontinuous populations exhibiting various levels of degradation. Using starch gel electrophoresis, we analyzed the polymorphism of nine isozymes in order to assess genetic diversity and structuring of 17 natural populations prospected in the three geographical regions and coinciding with subhumid, humid inferior and semi-arid superior bioclimates. The analysis of the level and the distribution of the genetic diversity in this species might help in its conservation. Out of the 18 loci detected for all populations and isozymes analyzed, 12 loci were polymorphic. Allelic frequencies differed according to populations and particular alleles characterized ecological groups. A high level of genetic variation within populations was observed. The mean number of alleles per polymorphic locus was Ap = 1.67, the percentage of polymorphic loci was P = 60.3% and the observed (Ho) and the expected (He) heterozygosities were respectively 0.144 and 0.215. Populations belonging to subhumid (Cap Bon) and semi-arid superior (Tunisian Dorsal) climates, located in degraded sites exhibited the highest level of inbreeding (0.425 < FIS < 0.450). A high level of differentiation (FST = 0.396) and a low gene flow (Nm = 0.337) among populations, as a result of habitat intermediate destruction, were revealed. The differentiation of populations within the same bioclimate (or geographic) group was substantial and relatively higher for semi-arid superior populations (FST = 0.262), which were more distant. The three ecological groups exhibited a high level of structuring (FST = 0.401). These differentiations might be due to geographic distances and to the variations of ecological factors between sites, including human activities and environmental factors. Nei’s (1972) genetic distances calculated between pairs of populations were globally low (0.006 < D < 0.367) with a mean of 0.15. They indicate a high level of similarity between populations. UPGMA clustering, established through Nei’s genetic distances, showed three population aggregates according to their geographic/bioclimatic appartenances. The high differentiation between populations and the low level of their genetic divergence indicated their recent isolation under anthropic pressures. The species conservation (in situ or ex situ) strategies should take into account the genetic diversity level within populations and its variation between geographic groups.  相似文献   

19.
Teosintes are the closest relatives to modern maize, Zea mays L. ssp. mays. They are wild grasses with a native distribution area from Mexico to Nicaragua and represent an important genetic resource. However, the genetic diversity of Nicaraguan teosinte (Zea nicaraguensis Iltis et Benz) has not yet been determined. This teosinte species has decreased in the last 25 years and now must be regarded as an endangered species. An analysis of the genetic diversity of Zea nicaraguensis was carried out in a total of 240 individuals from seven populations. Eleven Simple Sequences Repeat (SSR) primer pairs were used. A total of 42 alleles were found, the range of alleles per locus was 2–5 (mean 3.8) and the numbers of genotypes varied between primers. The primer Bnlg 1538 showed the highest value, with 45 genotypes through all populations. The genetic diversity observed (Ho) between all populations varied from 0.51 to 0.63, with an average of 0.563. One of the populations had as many as 40 alleles. Analysis of molecular variance (AMOVA) revealed that most of the variation was within population, at a significantly high level (P < 0.001). Rare alleles were detected in all populations, but unique alleles were only found in four populations. These results are highly relevant when developing conservation strategies and show that preserving populations in their natural habits is highly important.  相似文献   

20.
Deforestation in southeast Brazil has led to the extinction of Hymenaea courbaril var. stilbocarpa and ex situ conservation has been established. In this study, the levels of genetic diversity and the effective population size of H. courbaril in a germplasm bank were investigated using six nuclear microsatellite loci. A total of 79 and 91 alleles were found in 65 seed-trees and their 176 offspring, respectively. Offspring have a higher average number of alleles per locus (A = 15.2) than seed-trees (A = 13.2), but lower observed heterozygosity (offspring: H o = 0.566; seed-trees: H o = 0.607). The estimate of outcrossing rate shows that the study population is perfectly outcrossed (t m  = 0.978, P > 0.05). Significant deviations from random mating were detected through mating among relatives and correlated matings. The average variance in effective population size for each family was 2.63, with a total effective population size retained in the bank of 170.1. These results confirm that the preserved population of H. courbaril retains substantial genetic variability. Moacyr Antonio Mestriner and Ana Lilia Alzate-Marin—CEEFLORUSP Members.  相似文献   

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