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Overshadowed by the vast impact that habitat loss has on targeted plant species survival, it is easy to overlook the fact that utilization and harvesting of species can often result in their genetic depletion and in an often rapid downward trend of their population status. In this regard an ethnobotanical study on the medicinal plants of Shawar valley, District Swat was conducted with the aims to document medicinal plants and to examine the current status of the medicinal plants trade as well as the market chain starting from collectors to consumers. The survey reported 50 species of plants belonging to 33 families as ethnomedicinally important. These species were used as crud drugs by the local people and folk-lore for treating diseases in traditional system of medicine. The detailed local uses, recipe preparation along with their local names and diseases treated were recorded for each species.Market survey revealed that the structure of medicinal plant trade is complex and heterogeneous, involving many players. The collectors are often not aware of the high market prices and medicinal values, and most of the collected material is sold to local middlemen at a very low price. There was an increase of 3 to 5 folds in prices from collectors to the national market.Recommendations were given in the spheres of training sustainable harvesting and post harvesting of wild medicinal plant resources, trade monitoring, equitable sharing of benefits of wild resources, improved control on harvesting and trade for the conservation of resources, enhancement of cultivation efforts, future research into trade in wild harvested plants, community participation in natural resource management and value addition in the herbal products to maximize the benefits.  相似文献   

3.
The Kangchenjunga Landscape (KL) in the Eastern Himalayas is a transboundary complex shared by Bhutan, India, and Nepal. It forms a part of the ‘Himalayan Biodiversity Hotspot’ and is one of the biologically richest landscapes in the Eastern Himalayas. In this paper, we use secondary information to review and consolidate the knowledge on the flora of the KL. We reviewed 215 journal articles, analysed the history of publications on the flora of the KL, their publication pattern in terms of temporal and spatial distribution and key research areas. Our review shows that the landscape has a long history of botanical research that dates back to the 1840s and progressed remarkably after the 1980s. Most of the studies have been carried out in India, followed by Nepal and Bhutan. The majority of these have been vegetation surveys, followed by research on ethnobotanical aspects and Non-Timber Forest Products (NTFPs). This paper describes the forest types and characteristic species of the KL and details the species richness, diversity and dominant families of seed plants. A total of 5198 species of seed plants belonging to 1548 genera and 216 families have been recorded from the landscape, including 3860 dicots, 1315 monocots and 23 gymnosperms. Among families, Orchidaceae is the most diversely represented family in terms of species richness. This paper also draws attention to the threatened and endemic flora of the KL, including 44 species that are threatened at national and global level and 182 species that are endemic. Finally, the paper reviews the major challenges facing the KL, the conservation efforts and practices that are currently in place and recommends systematic and comprehensive floral surveys, particularly long-term data collection and monitoring and transboundary collaboration, to address the existing knowledge gaps on floral diversity of the KL.  相似文献   

4.
Although the degree of mate competition, given extreme differences in sex ratio, explains much of the pattern of male-biased size dimorphism among diverse taxa, it fails for some species which have potential for intense male competition for mates and yet exhibit little or no sexual size dimorphism (SSD). This fact suggest that species with low SSD should be express the effect of evolutionary pressure in non-obvious geometrical shape promoted by sex ratio in an evolutionary time scale. To evaluate this hypothesis we used phylogenetic comparative method in a Bayesian framework to investigate the evolution of SSD and the role of sex ratio at inter-specific level in the species of Ceroglossus (Coleoptera: Carabidae). In our results the proportion farthest from 1:1 is associated with more disparate body shape, even though the entire group has minimum variation in sex ratio, which is an intrinsic life history character of this group considering its phylogenetic conservatism or phylogenetic signal. We suggest that the sex ratio has determined the dimorphism degree during evolution of this group, since both traits have increased or decreased together during the species divergence (i.e. positive phylogenetic correlation: r2=0.85). We suggest that morphological studies of SSD will benefit from using comparative method with Bayesian approaches to assess the effect of phylogenetic history and its uncertainty. Finally, this will be allow to researchers to quantify the uncertainty of specific evolutionary hypotheses accounting for observed sexual dimorphism patterns.  相似文献   

5.
The population characteristics of distylous species are highly sensitive to stochastic natural selection pressure.Therefore,populations growing under different environmental conditions may vary in floral morph ratios,potentially affecting female fitness and leading to inbreeding depression.However,the variation in offspring quality among populations as a result of inbreeding depression is poorly understood in distylous species.This study investigates variations in plant density,seed mass,seed viabilityfemale fitness,and post-dispersal inbreeding depression in both sexual morphs(long-styled and shortstyled plants)of the distylous Primula nivalis that were subjected to different pollination treatments along an elevational gradient from 1657 to 2704 m a.s.l.Population characteristics(morph plant density and ratio)and fruit set were significantly affected by sexual morph and elevation.Plant density and fruitset frequencies were lower for short-styled than for long-styled plants at 2704 m a.s.l.The seeds from the cross-pollinated flowers of both morphs were higher in quality than those of self-pollinated flowers.The female fitness of seeds from cross-pollinated flowers of both morphs was higher than that of seeds from open-pollinated and self-pollinated flowers.The female fitness of seeds from long-styled flowers was higher than that of seeds from short-styled flowers at all elevations.Inbreeding depression increased with elevation among plants with short-styled flowers but not among those with long-styled flowers.Variation in the elevation-dependent mating system might influence female fitness and affect inbreeding depression in both floral morphs.In conclusion,the low quality of seeds from short-styled flowers at high elevations might decrease short-styled flower frequency,affecting population characteristics.  相似文献   

6.
Bacteria need a high degree of genetic stability to maintain their species identities over long evolutionary times while retaining some mutability to adapt to the changing environment.It is a long unanswered question that how bacteria reconcile these seemingly contradictory biological properties.We hypothesized that certain mechanisms must maintain a dynamic balance between genetic stability and mutability for the survival and evolution of bacterial species.To identify such mechanisms,we analyzed bacterial genomes,focusing on the Salmonella mismatch repair(MMR)system.We found that the MMR gene mutL functions as a genetic switch through a slipped-strand mispairing mechanism,modulating and maintaining a dynamic balance between genetic stability and mutability during bacterial evolution.This mechanism allows bacteria to maintain their phylogenetic status,while also adapting to changing environments by acquiring novel traits.In this review,we outline the history of research into this genetic switch,from its discovery to the latest findings,and discuss its potential roles in the genomic evolution of bacteria.  相似文献   

7.
Aquaculture has made an enormous contribution to the world food production,especially to the sustainable supply of animal proteins.The utility of diverse reproduction strategies in fish,such as the exploiting use of unisexual gynogenesis,has created a typical case of fish genetic breeding.A number of fish species show substantial sexual dimorphism that is closely linked to multiple economic traits including growth rate and body size,and the efficient development of sex-linked genetic markers and sex control biotechnologies has provided significant approaches to increase the production and value for commercial purposes.Along with the rapid development of genomics and molecular genetic techniques,the genetic basis of sexual dimorphism has been gradually deciphered,and great progress has been made in the mechanisms of fish sex determination and identification of sex-determining genes.This review summarizes the progress to provide some directive and objective thinking for further research in this field.  相似文献   

8.
A set of trisomics of Chinese cabbage was used for determining the n-I-1 gamete transmission rate and locating the gene controlling 2n gamete formation on the corresponding chromosome. The results showed that the transmission rates of extra chromosomes in different trisomics varied from 0% to 15.38% by male gametes and from 0% to 17.39% by female gametes. Of the nine F2 populations derived from the hybridizations between each trisomic and Bp058 (2n gamete material), only Tri- 4xBp058 showed that the segregation ratio of plants without 2n gamete formation to plants with 2n gamete formation was 10.38:1, which fitted the expected segregation ratio of the trisomics (AAa) based on the 7.37% of n+l gamete transmission through female and 5.88% through male. In other populations the segregation ratios varied from 2.48:1 to 3.72:1, which fitted the expected 3:1 segregation ratio of the bisomics (Aa). These results suggested that the gene controlling 2n gamete formation in Chinese cabbage Bp058 was located on chromosome 4. Further trisomic analysis based on the chromosome segregation and the incomplete stochastic chromatid segregation indicated that the gene locus was tightly linked to the centromere.  相似文献   

9.
Global climate change has led to the decline of species and functional diversity in ecosystems,changing community composition and ecosystem functions.However,we still know little about how species with different resource-use strategies(different types of resource usage and plant growth of plants as indicated by the spectrum of plant economic traits,including acquisitive resource-use strategy and conservative resource-use strategy) would change in response to climate change,and how the changes in...  相似文献   

10.
Woonyoungia septentrionalis (Dandy) Law is aceae. The floral morphology and structure of the species a dioecious species with unisexual flowers in Magnoliare conspicuously different from other species and are important to the study of floral phylogeny in this family. The floral anatomy and ontogeny were investigated to evaluate the systematic position of W. septentrionalis, using scanning electron microscopy and light microscopy. All of the floral organs are initiated acropetally and spirally. The carpels are of conduplicated type without the differentiation of stigma and style. The degenerated stamens in the female flowers have the same structures as the normal stamens at the earlier developmental stages, but they do not undergo successive development and eventually degenerate. The male floral apex was observed to have the remnants of carpels in a few investigated samples. As the bisexual flower features could be traced both in the male and female flowers in W. septentrionalis, it suggests that the flower sex in Magnoliaceae tends toward unisexual. As well as the unisexual flowers, the reduced tepals and carpels and concrescence of carpels conform to the specialized tendency in Magnoliaceae, which confirms the derived position of W. septentrionalis in this family. As the initiation pattern of floral parts of W. septentrionalis is very similar to other species in this family, it needs further investigation and especially comparison with species in Kmeria to evaluate the separation of Woonyoungia.  相似文献   

11.
Current patterns of floral design in Pedicularis must have undergone an evolutionary process of interacting among components of floral traits, and then formed internal relationships among these traits. To detect such correlations, which may provide insight to understand flower evolution, 40 Pedicularis species representing all corolla types of the genus were studied. Results show that, interspecifically, pollen size correlates negatively with pollen number, but positively with pistil length. This suggests that plants evolve an optimal pollen size, which balances the advantages of large pollen size for gametophytic competition against the fecundity disadvantages of fewer pollen grains. In contrast to sex allocation theory, this study does not find a trade-off, but an interspecific positive correlation between pollen and ovule number. This is consistent with the hypothesis that genetic variation for resource acquisition may in part be responsible for the lack of negative correlation between male and female function.This work was supported by the State Key Basic Research and Development Plan, China (Grant No. G2000046804) to YHG. The authors would like to thank Peter K. Endress and two anonymous reviewers for providing critical comments and helpful suggestions, Qing-Feng Wang, Jing-Yuan Wang and Jin-Ming Chen for their helpful suggestions. Shi-Guo Sun, Jing Xia, and Qian Yu are thanked for their assistance in both the field work and laboratory phases of the project.  相似文献   

12.
Theoretical models of the evolution of resource allocation patterns to male and female function make the assumption that there are inherent trade-offs between the two. Here we use a quantitative genetic approach to quantify trade-offs between male and female function and to determine whether plant populations could readily respond to natural selection by quantifying the amount of genetic variation for pollen and ovule production. Both intra- and interspecific crossing designs were applied to two populations of the predominantly outcrossing Mimulus guttatus and two populations of the highly selfing congener, M. micranthus. The only significant correlations observed among pollen number, pollen size and ovule number were positive. Positive genetic correlations among the traits were sometimes reduced after removing the effect of flower size but still no significant negative correlations were detected. These results suggest that positive correlations between pollen and ovule production may be due to the joint positive correlation of these characters with the resource pool available for pollen and ovule production, as reflected by flower size. Heritabilities were moderate to high for ovule production but low for pollen number and pollen size and suggest that responses to selection would differ between the two traits. Crosses between the species revealed that there are additional genetic factors contributing to differences between the two species for corolla width, vs. pollen:ovule ratio. This is consistent with the hypothesis that genetic variation for resource acquisition may in part be responsible for the overall lack of a negative correlation between pollen and ovule production and provides a genetic explanation for little evidence of trade-offs between sexual functions in Mimulus.  相似文献   

13.
Two widespread assumptions underlie theoretical models of the evolution of sex allocation in hermaphroditic species: (1) resource allocations to male and female function are heritable; and (2) there is an intrinsic, genetically based negative correlation between male and female reproductive function. These assumptions have not been adequately tested in wild species, although a few studies have detected either genetic variation in pollen and ovule production per flower or evidence of trade-offs between male and female investment at the whole plant level. It may also be argued, however, that in highly autogamous, perfect-flowered plant taxa that exhibit genetic variation in gamete production, strong stabilizing selection for an efficient pollen:ovule ratio should result in a positive correlation among genotypes with respect to mean ovule and mean pollen production per flower. Here we report the results of a three-generation artificial selection experiment conducted on a greenhouse population of the autogamous annual plant Spergularia marina. Starting with a base population of 1200 individuals, we conducted intense mass selection for two generations, creating four selected lines (high and low ovule production per flower; high and low anther production per flower) and a control line. By examining the direct and correlated responses of several floral traits to selection on gamete production per flower, we evaluated the expectations that primary sexual investment would exhibit heritable variation and that resource-sharing, variation in resource-garnering ability, or developmental constraints mold the genetic correlations expressed among floral organs. The observed direct and correlated responses to selection on male and female gamete production revealed significant heritabilities of both ovule and anther production per flower and a significant negative genetic correlation between them. When plants were selected for increased ovules per flower over two generations, ovule production increased and anther production declined relative to the control line. Among plants selected for decreased anthers per flower, we observed a decline in anther production and an increase in ovule production relative to the control line. In contrast, the lines selected for low ovules per flower and for high anthers per flower exhibited no evidence for significant genetic correlations between male and female primary investment. Correlated responses to selection also indicate a genetically based negative correlation between the production of normal versus developmentally abnormal anthers (staminoid organs); a positive correlation between the production of ovules versus staminoid organs; and a positive correlation between the production of anthers and petals. The negative relationship between male versus female primary investment supports classical sex allocation theory, although the asymmetrical correlated responses to selection indicate that this relationship is not always expressed.  相似文献   

14.
Floral diversification in the genus Pedicularis (Orobanchaceae) is remarkable among flowering plants. In this genus, floral morphology and pollinator behavior are closely co-adaptive. In the current paper, pollen grains of 23 representative species of Pedicularis mainly from North America, with two species from Japan and two species from China, whose pollination ecology was previously studied, were examined using light microscopy and scanning electron microscopy. Two pollen aperture types and three kinds of exine ornamentation were recognized among these species. In addition, pollen data from previous and the current studies of Pedicularis were integrated and analyzed, together with some pollination characters. There was a significant association between pollen aperture types and corolla types, as well as between pollination syndromes and corolla types. However, there was no association of exine ornamentations with corolla types. The relationships and evolution of this genus were discussed with regards to pollen morphology, corolla types and pollination syndromes.  相似文献   

15.
Aims Floral longevity, the duration that a flower remains open and functional, varies greatly among species. Variation in floral longevity has been considered to be optimal strategy for resource allocation under different ecological conditions, mainly determined by the rates of pollination and cost of flower maintenance. However, it is unclear whether an intrinsic factor, floral sexual investment, constrains evolution of floral longevity. The theoretical model also predicts that dichogamy favors long-lived flowers, but empirical studies to test this prediction remain unexplored.Methods To examine the effect of floral sexual investment on floral longevity, we measured flower size together with pollen and ovule production in 37 sympatric flowering plants in a natural community. The duration of the female and male phase in 21 protandrous species and floral longevity of the other 16 adichogamous species were documented in the field.Important findings Floral longevity varied from 1 day to 15 days, while pollen number per flower varied from 643 to 710880 and ovule number per flower from 1 to 426 in the 37 species. Flower size was correlated with pollen production as well as ovule production. Floral longevity was positively related to pollen production but not to ovule production. Consistent with the prediction that dichogamy favors long-lived flowers, we found the floral longevity of protandrous species was significantly longer than that of adichogamous species. In the protandrous species, pollen production per flower was observed to be positively related to male duration, while ovule production was not related to female duration. Our analyses of variation in floral longevity and sexual investment among different species suggest that the floral sexual investment could be an intrinsic factor contributing to the selected floral longevity, particularly the male phase, and that high pollen production could potentially increase pollen removal, i.e. male productive success.  相似文献   

16.
Abstract Theoretical models of the evolution of sex allocation generally assume a negative genetic correlation between components of male and female investment or function. To test this assumption, and to determine whether the expression of the correlation is sensitive to environmental conditions, we conducted an artificial selection experiment targeting primary sexual traits in the autogamous herb, Spergularia marina. Mass selection favouring individuals with high (or low) pollen and ovule production per flower had previously been conducted for two generations under uniform conditions. Following a third episode of selection (reported here) within the high‐pollen‐, high‐ovule‐, low‐pollen‐ and low‐ovule‐producing lineages, selected maternal seed families were replicated and cultivated in three nutrient treatments. With this design, we observed the effects of nutrient availability on: floral phenotype, the realized response to selection and the expression of genetic variation in, and covariation between, male and female investment. The first two episodes of selection Mazer et al. 1999 (Evolution 53:717–731) detected evidence for a genetically based negative correlation between ovule and anther production. Following the third episode of selection, phenotypic differences among the selected lines were maintained in all treatments, but evidence for a negative correlation between male and female investment nearly disappeared. Only under low‐nutrient conditions, in which plants selected for low ovule production exhibited elevated anther production, was a genetic trade‐off expressed. Either genetic drift or the combination of novel growing conditions (relative to previous generations) and G × E interactions may have caused the change in the expression of the genetic correlation. This experiment also allowed us to test the prediction that autogamous selfers should exhibit higher canalization of the ratio of male to female investment than of its components. Supporting this prediction, the A : O ratio was more strongly buffered against environmental variation than either anther or ovule production per flower.  相似文献   

17.
Strong covariation among traits suggests the presence of constraints on their independent evolution due to pleiotropy, to linkage, or to selective forces that maintain particular trait combinations. We examined floral trait covariation among individuals, among maternal families within and across populations, and over time, in greenhouse-raised plants of the autogamous Spergularia marina. We had three aims. First, since the phenotype of traits expressed by modular organs often changes as individuals age, estimates of the degree of genetic covariation between such traits may also change over time. To seek evidence for this, we measured weekly (for five weeks) an array of floral traits among plants representing ~ 10 maternal families from each of four populations. The statistical significance of the phenotypic and among-family correlations among traits changed over time. Second, we compared populations with respect to trait covariation to determine whether populations or traits appear to be evolving independently of one another. Differences observed among populations suggest that they have diverged genetically. Third, we sought correlations that might reflect constraints on the independent evolution of floral traits. Investment in another and ovule production per flower vary independently among maternal families; there was no evidence for a “trade-off” between male and female investment. We propose that in autogamous taxa one should not find a negative correlation between pollen and ovule production per flower, as such taxa cannot evolve sexual specialization and should be under strong selection to maintain an efficient pollen:ovule ratio, preventing the evolution of male-biased or female-biased genotypes. We found that other pairs of floral traits, however, expressed highly signficant correlation coefficients, suggesting the presence of some evolutionary constraints, at least within some populations, although their strength depended on exactly when flowers were sampled.  相似文献   

18.
Sympatric populations of Pedicularis oederi, P. cystopteridifolia, and P. groenlandica on the Beartooth Plateau (Montana) were obligately dependent on Bombus pollinators. Their corolla colors were mutually distinct to insect vision, but their nectars had identical sugar components. Analysis of corbicular pollen loads of pollinating insects indicated a high degree of polylecty. Queen/worker ratios of pollinators on plant species corresponded to the parallel phenological sequences of plant blooming and insect caste development. The total number of individual pollinators of each Bombus species on all plants was directly related to the number of plant species it pollinated, but a comparable relationship between the number of pollinators on a plant species to the number of Bombus species pollinating it was not found. Morphological and behavioral correspondence of floral mechanisms and pollinators form an integral part of the general pattern of coadaptive evolution of the floral ecology of Pedicularis in North America known from previous studies. Reproductive isolation between Pedicularis species in this study is attributed to internal barriers. Wide overlaps of blooming seasons, proboscis lengths of bumblebee species and castes, and pollinator species on Pedicularis species suggest resource sharing, rather than resource partitioning or competition for resources among plant and insect species and individuals.  相似文献   

19.
Pollen size varies little within angiosperm species, but differs extensively between species, suggesting the action of strong selection. Nevertheless, the potential for genetic responses of pollen size to selection, as determined by additive genetic variance and genetic correlations with other floral traits, has received little attention. To assess this potential, we subjected Brassica rapa to artificial selection for large and small pollen during three generations. This selection caused significant divergence in pollen diameter, with additive genetic effects accounting for over 30% of the observed phenotypic variation in pollen size. Such heritable genetic variation suggests that natural selection could effect evolutionary change in this trait. Selection on pollen size also elicited correlated responses in pollen number (–), flower size (+), style length (+), and ovule number (+), suggesting that pollen size cannot evolve independently. The correlated responses of pollen number, flower size and ovule number probably reflect the genetically determined and physically constrained pattern of resource allocation in B. rapa. In contrast, the positive correlation between pollen size and style length may represent a widespread gametic‐phase disequilibrium in angiosperms that arises from nonrandom fertilization success of large pollen in pistils with long styles.  相似文献   

20.
Six native species of Pedicularis in Mount Rainier National Park in Washington State were studied for their reproductive relationships with animal pollinators. Cinematographic and stereophotographic records revealed pollination of the nectariferous P. bracteosa and P. rainierensis by upright, nectar-foraging queens and workers of five bumblebee (Bombus Latr.) species and by inverted workers scraping pollen from anthers concealed within the corolla galea. The nectarless, rostrate flowers of P. contorta, P. groenlandica, P. ornithorhyncha, and P. racemosa were pollinated by pollen-foraging workers and occasional queens virbrating pollen from concealed anthers. Insect exclosure methods revealed complete absence of fruiting in the absence of insects, and pollinator collections further indicate obligate dependence of the plants upon bumblebees for their sexual reproduction. Analysis of corbicular pollen loads from pollinators suggested that pollinator species are not monolectic but that individual pollinators range from monolectic to polylectic. Measurements indicated limited correlations between lengths of corolla tubes and tongues of nectar-foraging insects. Each nectarless Pedicularis species occupied a different, specific habitat, but P. bracteosa and the endemic P. rainierensis were sympatric in part. Each species had a unique spectral reflectance pattern from the corolla. Proximity of habitats and overlap of blooming periods of all Pedicularis species eliminate the possibility of contemporary geographic or phenological reproductive isolation. It is suggested that behavioral interactions of the plants and their insect pollinators may have been instrumental in the past in reproductively isolating these species, hybrids of which are unknown.  相似文献   

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