首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
One hundred ninety-four germplasm accessions of fig representing the four fig types, Common, Smyrna, San Pedro, and Caprifig were analyzed for genetic diversity, structure, and differentiation using genetic polymorphism at 15 microsatellite loci. The collection showed considerable polymorphism with observed number of alleles per locus ranging from four for five different loci, MFC4, LMFC14, LMFC22, LMFC31 and LMFC35 to nine for LMFC30 with an average of 4.9 alleles per locus. Seven of the 15 loci included in the genetic structure analyses exhibited significant deviation from panmixia, of which two showed excess and five showed deficiency of heterozygote. The cluster analysis (CA) revealed ten groups with 32 instances of synonymy among cultivars and groups differed significantly for frequency and composition of alleles for different loci. The principal components analysis (PCA) confirmed the results of CA with some groups more differentiated than the others. Further, the model based Bayesian approach clustering suggested a subtle population structure with mixed ancestry for most figs. The gene diversity analysis indicated that much of the total variation is found within groups (H G /H T = 0.853; 85.3%) and the among groups within total component (G GT = 0.147) accounted for the remaining 14.7%, of which ~64% accounted for among groups within clusters (G GC = 0.094) and ~36% among clusters (G CT = 0.053). The analysis of molecular variance (AMOVA) showed approximately similar results with nearly 87% of variation within groups and ~10% among groups within clusters, and ~3% among clusters. Overall, the gene pool of cultivated fig analyzed possesses substantial genetic polymorphism but exhibits narrow differentiation. It is evident that fig accessions from Turkmenistan are somewhat genetically different from the rest of the Mediterranean and the Caucasus figs. The long history of domestication and cultivation with widespread dispersal of cultivars with many synonyms has resulted in a great deal of confusion in the identification and classification of cultivars in fig.  相似文献   

2.
为了探讨榕树隐头果的发育期、性别、大小等外部特征对传粉榕小蜂选择的影响,采取人为控制雌花期的方法,对鸡嗉子榕(Ficus sermicordata)及其传粉榕小蜂(Ceratosolen gravelyi)的选择行为进行研究。结果表明,在隐头花序发育到雌花期后,如果阻止传粉小蜂进入,隐头果会继续生长。直径较小的雌果和雄果的进蜂量较多,且在雌雄果同时存在时,小蜂仍然会选择进入雌果,但进蜂量显著低于雄果。小蜂优先选择进入雌花期前期的隐头花序,雌雄果皆有此特点。对于相同发育期的隐头果,果径和进蜂量呈正相关关系,说明对于相同发育期的隐头果,小蜂更倾向于进入较大的隐头果。因此,真正控制小蜂行为的是隐头花序所处的发育期,以及不同发育期所产生的化学挥发物,而非隐头果直径大小。这为进一步研究榕-蜂系统的稳定机制提供依据。  相似文献   

3.
Genetic variation among the isolates of Fusarium oxysporum f. sp. ciceris, the causal agent of chickpea wilt worldwide, was analysed using pathogenicity tests and molecular markers – random amplified polymorphic DNA (RAPD) and inter‐simple sequence repeat (ISSR) polymorphism. Hundred and eight isolates were obtained from diseased chickpea plants in 13 different provinces of Turkey, out of which 74 isolates were assessed using 30 arbitrary decamer primers and 20 ISSR primers. Unweighted pair‐grouped method by arithmetic average cluster analysis of RAPD, ISSR and RAPD + ISSR datasets provided a substantially similar discrimination among Turkish isolates and divided into three major groups. Group 1, 2 and 3 consisted of 41, 18 and 15 isolates, respectively. These methods revealed a considerable genetic variation among Turkish isolates, but no correlation with regard to the clustering of isolates from different geographic regions. Analysis of molecular variance confirmed that most genetic variability resulted from the differences among isolates within regions. Our results also indicated that the low‐genetic differentiation (FST) and high gene flow (Nm) among populations had a significant effect on the emergence and evolutionary development of F. oxysporum f. sp. ciceris. This is the first report on genetic diversity and population structure of F. oxysporum isolates on chickpea in Turkey.  相似文献   

4.
The genetic diversity in Tunisian fig (Ficus carica L.) was studied using RAPD markers. Thirty-five fig cultivars originating from diverse geographical areas and belonging to three collections were analysed. Random decamer primers were screened to assess their ability to detect polymorphisms in this crop. Forty-four RAPD markers were revealed and used to survey the genetic diversity and to detect cases of mislabelling. As a result, considerable genetic diversity was detected among the studied F. carica accessions. The relationships among the 35 varieties were studied by cluster analysis. The dendrogram showed two main groups composed of cultivars with similar geographic origin. Moreover, the male accessions (caprifigs) were clustered indistinctively within the female ones, suggesting a narrow genetic diversity among these accessions. Our data proved that RAPD markers are useful for germplasm discrimination as well as for investigation of patterns of variation in fig. Since this designed procedure has permitted to establish a molecular database of the reference collections, the opportunity of this study is discussed in relation to the improvement and rational management of fig germplasm.  相似文献   

5.
 Twenty Pisolithus tinctorius isolates from different geographic locations and different hosts were characterized by the random amplified polymorphic DNA technique. Thirteen arbitrary primers generated 87 DNA fragments, all of them polymorphic. These data were used to calculate genetic distances among the isolates. The pairwise genetic distances ranged from 1 to 100%, with an average of 58.7%. Cluster analysis based on the amplified fragments grouped the isolates according to their host and geographical origins. Group I contained isolates collected in Brazil and group II those collected in the Northern Hemisphere. In addition to the diversity seen at the molecular level, the isolates also showed host specificity. Greenhouse experiments demonstrated that isolates from the Northern Hemisphere colonized mainly Pinus whereas isolates from Brazil colonized only Eucalyptus. The molecular data suggest that the Pisolithus tinctorius isolates analyzed belong to two distinct groups. The data also suggest new guidelines for future investigations on the taxonomy and systematic of this important fungus species. Furthermore, these results support future experiments aimed at the selection and development of improved isolates of P. tinctorius. Accepted: 3 October 1997  相似文献   

6.
Constraints and evolution are central for the resolution of conflicts between mutualism species and for the stability of mutualisms. Dioecious fig species and their specific pollinators are also in conflict on the use of fig ovaries. Here, our experiments provided some data on the female florets allocation in two dioecious fig trees. The results showed that: (1) there is a bimodal distribution in the style–length of two fig trees’ female florets, moreover, the style–lengths are fairly similar and narrowly distributed in gall figs and more variation seems to occur in seed figs; (2) the styles in seed figs are a little longer than those in gall figs; (3) the pollinator's ovipositor lengths are shorter than the style–lengths in seed figs, but they are very similar to those in gall figs so that pollinators can only lay their eggs into the ovaries of gall figs, but not in seed figs; (4) the stigmas stick together, and the style is curly and flexible in seed syconia of the two fig species studied, so it is very difficult for the pollinators to find suitable ovipositing sites and lay their eggs in seed figs; (5) the variations of style-lengths are bigger in seed figs than gall figs, but they are smaller in dioecious figs than monoecious figs; (6) for Ficus cyrtophylla, about 10% styles are shorter in seed figs than those in gall figs, even shorter than ovipositor. In contrast, about 2% styles in gall figs of Ficus hispida are longer than its corresponding pollinator's ovipositor. In a word, our study suggests that the female floret's fate in these two fig species is mainly dependent on its style–length, but not all. The stigma shape and the floral organization can both also attribute to their fate in the two fig species studied.  相似文献   

7.
1. Figs on male dioecious fig trees (Ficus, Moraceae) are breeding sites for pollinator fig wasps (Hymenoptera, Agaonidae), but figs on female plants are traps that produce only seeds. As the short‐lived fig wasps cannot reproduce in female figs, natural selection should favour individuals that avoid them. Several studies have failed to detect such discrimination, a result attributed to inter‐sexual mimicry and ‘selection to rush’ in the wasps, but their experiments failed to explicitly take into account fig age (how long they had been waiting to be pollinated). 2. We compared the relative attraction of male and female figs of known ages of the South East Asian Ficus montana Burm. f. to its pollina tor Liporrhopalum tentacularis Grandi and examined how the reproductive success of the plant and its pollinator change with the age of the figs. 3. Mean retention time for un‐pollinated figs on female plants was 16 days whereas in male figs it was 12 days. Female figs remained attractive for up to 2 weeks, although the wasps were less willing to enter older figs. After pollinator entry, receptivity continued for several days, lasting longer in figs entered by a single wasp. Consistent with abortion rates, attractiveness persisted longer in female figs. Older figs produced fewer fig wasp offspring, but similar numbers of seeds. 4. The sexual differences in floral longevity in F. montana may represent part of a previously un‐recognised reproductive strategy in some fig trees that allows male plants to ‘export’ pollinators while also maintaining a resident fig wasp population.  相似文献   

8.
Shovelnose sturgeon (Scaphirhynchus platorhynchus) caviar fisheries exist in several states throughout the Mississippi River drainage. Management of these fisheries may benefit from information about genetic stock structure. Sixteen microsatellite loci and morphological analysis were used to examine geographic stock structure of shovelnose sturgeon among seven geographic locations: five within continuous shovelnose sturgeon habitat, and two isolated by artificial barriers. Tissue samples were collected from 1999 to 2006 from the upper Missouri, Platte, lower Missouri, middle Mississippi, Ohio, Wabash, and Atchafalaya rivers. Geographic samples of shovelnose sturgeon samples could be separated into three groups with discriminate function analysis of four morphological characters. The microsatellite loci were highly variable (allelic richness range 5.65–13, observed heterozygosity range 0.64–0.89). Bayesian clustering did not identify multiple groups in the genetic data. However, significant genetic differentiation (θST = 0.017, P < 0.0001) was observed among a priori defined geographic samples and all pairwise estimates of θST were significant. Assignment testing among a priori defined groups indicated that the sturgeon from the upper Missouri, Platte, and Atchafalaya rivers had the highest assignment scores and thus were most distinct, while the lower Missouri and the middle Mississippi were less distinct and a larger fraction of the sturgeon from these rivers was genetically assigned to other rivers. The Ohio and Wabash rivers were genetically most similar. A Mantel test revealed a positive relationship between genetic and geographic distance (r = 0.464, P = 0.055) that was not statistically significant. The level of genetic differentiation observed at both molecular and morphological characters suggests that multiple shovelnose sturgeon populations may exist within the studied area, yet demographic factors and possible gene flow may have minimized the amount of genetic differentiation among locations.  相似文献   

9.
The structure of populations across landscapes influences the dynamics of their interactions with other species. Understanding the geographic structure of populations can thus shed light on the potential for interacting species to co‐evolve. Host–parasitoid interactions are widespread in nature and also represent a significant force in the evolution of plant–insect interactions. However, there have been few comparisons of population structure between an insect host and its parasitoid. We used microsatellite markers to analyse the population genetic structure of Pleistodontes imperialis sp. 1, a fig‐pollinating wasp of Port Jackson fig (Ficus rubiginosa), and its main parasitoid, Sycoscapter sp. A, in eastern Australia. Besides exploring this host–parasitoid system, our study also constitutes, to our knowledge, the first study of population structure in a nonpollinating fig wasp species. We collected matched samples of pollinators and parasitoids at several sites in two regions separated by up to 2000 km. We found that pollinators occupying the two regions represent distinct populations, but, in contrast, parasitoids formed a single population across the wide geographic range sampled. We observed genetic isolation by distance for each species, but found consistently lower FST and RST values between sites for parasitoids compared with pollinators. Previous studies have indicated that pollinators of monoecious figs can disperse over very long distances, and we provide the first genetic evidence that their parasitoids may disperse as far, if not farther. The contrasting geographic population structures of host and parasitoid highlight the potential for geographic mosaics in this important symbiotic system.  相似文献   

10.
1. Facilitation is recorded from diverse plant–insect interactions, including pollination and herbivory. 2. The significance of facilitation resulting from the behavior of males of multiple fig wasp species inside figs was investigated. Female fig wasps emerge from natal figs via exit holes dug by males, especially male pollinators. When no males are present, the females struggle to escape and may die. 3. Ficus microcarpa L. is a widely‐established invasive fig tree from Southeast Asia. Its pollinator is absent in South Africa, so the tree cannot reproduce, but two Asian non‐pollinating fig wasps (NPFW) Walkerella microcarpae and Odontofroggatia galili occupy its figs. Abundance patterns of the two NPFW and the proportion of male‐free figs in South Africa, Spain (where the pollinator is introduced), and in China, where the native fig wasp community is diverse, were compared to determine the consequences of reduced species richness for insect survival. 4. Female fig wasps in male‐free figs were found to be trapped, and small clutch sizes contributed to the absence of males in both species. The presence of pollinators in Spain allowed most NPFW to develop in figs containing males. Far more male‐free figs were present in South Africa, elevating mortality rates among female NPFW. Facilitation of female release by males of other NPFW species nonetheless benefitted the rarer species. 5. Selection pressures in South Africa currently favour greater aggregation of NPFW offspring and/or less female biased sex ratios.  相似文献   

11.
The interaction between figs (Ficus spp., Moraceae) and their pollinator fig wasps (Hymenoptera: Agaonidae) is an obligate mutualism, but females of dioecious fig trees exploit fig wasps without providing rewards. Figs are closed inflorescences that typically trap pollinator females after entry, but some fig wasp species can re‐emerge (although wingless) and subsequently oviposit in and pollinate further figs. Using glasshouse populations, we examined the sex ratios and clutches laid by single foundresses of Kradibia tentacularis (Grandi) in their first and subsequent male figs of Ficus montana Blume, and how the probability of emergence and entering a second fig varied between seasons. A maximum of four figs were entered by any one foundress. Wingless foundresses were able to locate and enter figs up to 60 cm from the first fig they entered, but the probability of entry declined sharply with distance from that fig. The foundresses that re‐emerged produced slightly higher adult offspring totals than those that failed to re‐emerge. Clutch sizes of a single foundress in its first fig equalled those in all the subsequent figs combined, with clutch size per fig decreasing when more figs were entered. Smaller clutches had less female‐biased sex ratios. Figs were more numerous in summer than in winter, but the proportion of figs entered by only wingless foundresses remained unchanged. Movement between figs increases pollinator reproductive success in male figs, thereby encouraging foundresses that encounter a female tree to also move between and pollinate several female figs.  相似文献   

12.
The host-specific relationship between fig trees (Ficus) and their pollinator wasps (Agaonidae) is a classic case of obligate mutualism. Pollinators reproduce within highly specialised inflorescences (figs) of fig trees that depend on the pollinator offspring for the dispersal of their pollen. About half of all fig trees are functionally dioecious, with separate male and female plants responsible for separate sexual functions. Pollen and the fig wasps that disperse it are produced within male figs, whereas female figs produce only seeds. Figs vary greatly in size between different species, with female flower numbers varying from tens to many thousands. Within species, the number of female flowers present in each fig is potentially a major determinant of the numbers of pollinator offspring and seeds produced. We recorded variation in female flower numbers within male and female figs of the dioecious Ficus montana growing under controlled conditions, and assessed the sources and consequences of inflorescence size variation for the reproductive success of the plants and their pollinator (Kradibia tentacularis). Female flower numbers varied greatly within and between plants, as did the reproductive success of the plants, and their pollinators. The numbers of pollinator offspring in male figs and seeds in female figs were positively correlated with female flower numbers, but the numbers of male flowers and a parasitoid of the pollinator were not. The significant variation in flower number among figs produced by different individuals growing under uniform conditions indicates that there is a genetic influence on inflorescence size and that this character may be subject to selection.  相似文献   

13.
To study interactions between host figs and their pollinating wasps and the influence of climatic change on their genetic structures, we sequenced cytoplasmic and nuclear genes and genotyped nuclear microsatellite loci from two varieties of Ficus pumila, the widespread creeping fig and endemic jelly fig, and from their pollinating wasps, Wiebesia pumilae, found in Taiwan and on nearby offshore islands. Great divergence in the mitochondrial cytochrome c oxidase subunit I (mtCOI) with no genetic admixture in nuclear markers indicated that creeping‐ and jelly‐fig wasps are genetically distinct. Compared with creeping‐fig wasps, jelly‐fig wasps also showed better resistance under cold (20 °C) than warm (25 and 30 °C) conditions in a survival test, indicating their adaptation to a cold environment, which may have facilitated population expansion during the ice age as shown by a nuclear intron and 10 microsatellite loci. An excess of amino acid divergence and a pattern of too many rare mtCOI variants of jelly‐fig wasps as revealed by computer simulations and neutrality tests implied the effect of positive selection, which we hypothesize was associated with the cold‐adaptation process. Chloroplast DNA of the two fig plants was completely segregated, with signs of genetic admixture in nuclear markers. As creeping‐ and jelly‐fig wasps can pollinate creeping figs, occasional gene flow between the two figs is thus possible. Therefore, it is suggested that pollinating wasps may be playing an active role in driving introgression between different types of host fig.  相似文献   

14.
In Central Europe, salt-influenced habitats are restricted mainly to the coastlines of the North Sea and the Baltic Sea. The few natural inland salt sites suffer from size reduction and loss in biodiversity, while anthropogenic salt sites around potash mining dumps experienced recent and massive de novo colonization by numerous halophytes. Our study aimed to elucidate the general patterns of gene flow among coastal and inland salt habitats. We used amplified fragment length polymorphisms to assess the genetic diversity and genetic structure of 18 European populations of the halophyte Spergularia media (Caryophyllaceae), sampled from inland and coastal salt sites of Germany, the Netherlands, Denmark, Austria, France and Italy. Estimates of genetic diversity on the population level were generally low, especially within inland salt habitats. Analyses of molecular variance showed comparatively strong differentiation among populations. Multivariate ordination (principal coordinate analysis) and a NeighborNet analysis revealed four distinct groups of populations that showed good correspondence to their geographic origins. A Bayesian analysis performed with the program Structure as well as high pairwise Φ ST values supported the results of the phenetic analyses. The observed patterns of diversity and differentiation among inland populations of S. media are best explained by the isolated nature of suitable salt habitats, with concomitant reduction of gene flow to and among these sites. Our data support the hypothesis that the colonization of anthropogenic salt sites by S. media originated from natural inland habitats.  相似文献   

15.
Fig trees (Ficus: Moraceae) are pollinated by female fig wasps (Agaonidae) whose larvae develop inside galled flowers of unusual inflorescences (figs). Most fig trees also support communities of non‐pollinating fig wasps. Figs of different species display great size variation and contain tens to tens of thousands of flowers. Around one‐half the species of fig trees have the gynodioecious breeding system, where female trees have figs that produce seeds and male trees have figs that support development of pollinators. Mutual mimicry between receptive male and female figs ensures that pollinators enter female figs, even though the insects will die without reproducing, but the need to give no sex‐specific cues to the pollinators may constrain differences in size between receptive male and female figs. We compared relationships between inflorescence size and some measures of reproductive success in male and female figs of Ficus montana grown under controlled conditions in the presence of the pollinator Kradibia tentacularis and its main parasitoid Sycoscapter sp. indesc. Female figs that contained more flowers produced more seeds, but male figs did not increase the production of female pollinator K. tentacularis fig wasps in proportion of the flower number. Although more flowers were galled by the pollinators in male figs containing more female flowers, the high larval mortality caused by parasitism and nutritional limitation prevented the increase in the production of adult female offspring. Selection may favor the increase in flower numbers within figs in female plants of F. montana, but contrarily constrain this attribute in male plants.  相似文献   

16.
In the dioecious fig/pollinator mutualism, the female wasps that pollinate figs on female trees die without reproducing, whereas wasps that pollinate figs on male trees produce offspring. Selection should strongly favour wasps that avoid female figs and enter only male figs. Consequently, fig trees would not be pollinated and fig seed production would ultimately cease, leading to extinction of both wasp and fig. We experimentally presented pollinators in the wild (southern India) with a choice between male and female figs of a dioecious fig species, Ficus hispida L. Our results show that wasps do not systematically discriminate between sexes of F. hispida. We propose four hypotheses to explain why wasp choice has not evolved, and how a mutualism is thus maintained in which all wasps that pollinate female figs have zero fitness.  相似文献   

17.
Figs (Ficus, Moraceae) are either monoecious or gynodioecious depending on the arrangement of unisexual florets within the specialized inflorescence or syconium. The gynodioecious species are functionally dioecious due to the impact of pollinating fig wasps (Hymenoptera: Agaonidae) on the maturation of fig seeds. The evolutionary relationships of functionally dioecious figs (Ficus subg. Ficus) were examined through phylogenetic analyses based on the internal transcribed spacer (ITS) region of nuclear ribosomal DNA and morphology. Forty-six species representing each monoecious subgenus and each section of functionally dioecious subg. Ficus were included in parsimony analyses based on 180 molecular characters and 61 morphological characters that were potentially informative. Separate and combined analyses of molecular and morphological data sets suggested that functionally dioecious figs are not monophyletic and that monoecious subg. Sycomorus is derived within a dioecious clade. The combined analysis indicated one or two origins of functional dioecy in the genus and at least two reversals to monoecy within a functionally dioecious lineage. The exclusion of breeding system and related characters from the analysis also indicated two shifts from monoecy to functional dioecy and two reversals. The associations of pollinating fig wasps were congruent with host fig phylogeny and further supported a revised classification of Ficus.  相似文献   

18.
Do xeric landscapes increase genetic divergence in aquatic ecosystems?   总被引:1,自引:0,他引:1  
1. Previous investigations of the ecological genetics among amphipods in south-western U.S.A. suggested a xeric landscape promoted genetic divergence among passively dispersed freshwater invertebrates, thereby enhancing speciation events. We predicted that less divergence would occur among amphipod populations across similar geographic distances in mesic regions. 2. Eight Hyalella azteca populations were sampled along a 200-km transect in western Oregon, U.S.A. Genetic distances among populations were estimated from randomly amplified polymorphic DNA (RAPD). Genetic analyses indicated much less divergence among Oregon populations than among Arizona populations in an arid environment. 3. Behavioural observations support the genetic data: Oregon populations exhibit little differentiation in swimming behaviour, whereas Hyalella populations in Arizona exhibit extremes in swimming behaviour. 4. These results provide preliminary support for the hypothesis that a xeric landscape promotes genetic and behavioural divergence among amphipods. Many aquatic invertebrates classified as panmictic populations may encompass genetically distinct groups; those isolated by a xeric landscape are especially prone to diversification.  相似文献   

19.
采用ISSR分子标记技术对来源于不同地区的19份药用菊花(Dendranthema morifolium Ramat.)种源、4份野菊(D.indwum L.)种源、1份菊花脑(D.nankingese Hand.-Mazz.)种源和1份杂交菊花‘黄金菊’(D.indium×D.morifolium‘Gongju’)种源进行了遗传关系分析。从38条引物中筛选出6条引物,共扩增出66条带,平均多态性条带百分率达95.5%。聚类分析结果表明,取λ=16,25份种源可分成2大组,即野菊、菊花脑和杂交菊花归为一组,19份药用菊花种源归为一组;19份药用菊花种源又可根据原产地进一步分成2组,大部分原产北方的药用菊花种源的遗传关系较近,而大部分南方栽培的药用菊花种源也有相对较近的遗传关系。  相似文献   

20.
This study investigates dioecious fig species using a pollinator introduction experiment. Our aims were to determine: (1) whether there was a significant difference in foundress distribution between sexes per fig species; (2) whether fig size and foundress number affect reproductive success of dioecious figs; and (3) who is the ‘controlling partner’ in the fig/pollinator mutualism. Three dioecious fig species: Ficus semicordata, Ficus hispida and Ficus tinctoria from Xishuangbanna, China, were selected for this experiment. We found that there was no significant difference of the foundress number in female and male figs of F. semicordata, F. hispida and F. tinctoria. Also, the foundress number did not depend on the fig diameter. The numbers and the proportions of fig seeds and female wasp offspring significantly increased with more foundresses; and fig seed number was significantly higher than female wasp offspring in F. semicordata and F. hispida, but not in F. tinctoria. Our results indicate that figs are generally the ‘controlling partner’ in fig-wasp mutualisms in species with large figs, but not with small figs. Compared with published studies of reproductive success in monoecious figs, the dioecious figs seem to be more efficient in producing both seeds and wasp offspring when there is a high number of foundress.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号