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1.
Epidendrum is one of the largest Neotropical genera of Orchidaceae and comprises approximately 1500 species. Only 2.8% of these species have been studied cytologically, demonstrating chromosome numbers ranging from n = 12 in E. fulgens to n = 120 in E. cinnabarinum. The present work evaluated the evolution of the karyotypes of Epidendrum spp. based on data gathered from the literature and from analyses of the karyotypes of 16 Brazilian species (nine previously unpublished). The appearance of one karyotype with n = 12 with one larger chromosome pair in subgenus Amphiglottium appears to have occurred at the beginning of the divergence of this lineage, and x = 12 probably represents the basic number of this subgenus. Epidendrum secundum exhibits wide variation in chromosome numbers, with ten different cytotypes found in 22 Brazilian populations, seven of which were new counts: 2n = 30, 42, 50, 54, 56, 58 and 84. Most lineages of Epidendrum seem to have been secondarily derived from one ancestral stock with x = 20, as is seen in the majority of the present‐day representatives of the genus. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172 , 329–344.  相似文献   

2.
Hybridization has the potential to contribute to phenotypic and genetic variation and can be a major evolutionary mechanism. However, when hybridization is extensive it can also lead to the blurring of species boundaries and the emergence of cryptic species (i.e., two or more species not distinguishable morphologically). In this study, we address this hypothesis in Epidendrum, the largest Neotropical genus of orchids where hybridization is apparently so common that it may explain the high levels of morphological diversity found. Nonetheless, this hypothesis is mostly based on the intermediacy of morphological characters and intermediacy by itself is not a proof of hybridization. Therefore, in this study, we first assessed the existence of hybrids using cpDNA and AFLP data gathered from a large-scale sampling comprising 1038 plants of three species of Epidendrum (E. calanthum, E. cochlidium and E. schistochilum). Subsequently, a Bayesian assignment of individuals into different genetic classes (pure species, F1, F2 or backcross generations) revealed that hybrid genotypes were prevalent in all sympatric populations. In most cases, parental species were not assigned as pure individuals, rather consisting in backcrossed genotypes or F1 hybrids. We also found that reproductive barriers are apparently very weak in Epidendrum because the three species largely overlapped in their flowering periods and interspecific crosses always produced viable seeds. Further, hybridization contributed to enhance floral variability, genome size and reproductive success since we found that these traits were always higher in hybrid classes (F1, F2 and backcrosses) than in pure parental species, and offer an explanation for the blurring of species boundaries in this genus of orchids. We hypothesize that these natural hybrids possess an evolutionary advantage, which may explain the high rates of cryptic species observed in this genus.  相似文献   

3.
Pinus maximartinezii is a rare, endemic, threatened species known from a single small population in the state of Zacatecas, Mexico. Among the pine species that produce edible nuts, it produces one of the largest and most nutritious seeds. The seeds of P. maximartinezii have historically been used for human consumption. The cones are harvested directly from the trees, and the seeds are sold illegally in local, national and international markets. However, the effects of seed extraction must be thoroughly evaluated to determine the potential impacts on population stability. To assess the impact of different rates of seed harvesting on the demography of this species, a 2-yr study of population dynamics was conducted in three 0.1-ha plots. A 9 × 9 size-structured matrix model was used to simulate changes in population growth over time in conjunction with increasing stepwise reductions in fecundity. The population growth rate (λ) of P. maximartinezii was 1.1175, with a 95% confidence interval (CI) from 1.1008 to 1.1321, and it was relatively insensitive to changes in fecundity and growth. Under a seed extraction intensity of 99%, λ decreased to 1.0241, with a CI from 1.0177 to 1.0361. Elasticity analysis was then performed to identify the combined effects of proportional changes in fecundities and the largest stasis elements on λ. The results suggest that a sound conservation strategy should focus on improving the survival of juveniles and adults during their first reproductive events and on the largest adults, as well as on protecting the habitat of this threatened endemic species.  相似文献   

4.
Forecasting the impacts of climate change on species distribution has several implications for conservation. Plinia edulis is a rare and threatened tree species from Brazilian Atlantic Rainforest. In this study, we assessed the impact of global climate change on the distribution of P. edulis. Additionally, we evaluated the efficacy of the Brazilian protected network to conserve this species. Ecological niche models were built using the maximum entropy method based on occurrence records and environmental predictors. Models predicted a reduction of climatically suitable areas for P. edulis in all evaluated scenarios in the coming years. Furthermore, we observed that Brazilian protected areas (PAs) are ineffective to conserve this species. Given the fact that P. edulis is a promising tree species rarely found within Brazilian PAs and threatened by global climate change, we strongly recommend the cultivation of this multipurpose species in agroforestry systems, landscaping and homegardens in order to promote its conservation through sustainable use.  相似文献   

5.
The genusBarkeria (Orchidaceae) consists of four species and eight subspecies (the treatment includes a key) of epiphytic plants endemic to Mexico and Central America.Barkeria is separated from the genusEpidendrum on the structure of the rostellum and column in the flower, plus shape of the pseudobulbs. The authors suggest thatBarkeria is most closely related toCaularthron based on the general shape of the flowers, widely spreading fleshy column wings, and structure of the rostellum.  相似文献   

6.
《Flora》2014,209(5-6):250-259
Inselbergs support highly specialized vegetation with many endemic species. Here we studied by an integrated approach a rare and threatened species from Brazilian inselbergs. Pitcairnia encholirioides (Bromeliaceae) is included in the Red Book of Brazilian Flora, in the ‘Endangered’ category. Only one single population on unprotected private property was known at the beginning of our study. We studied several life-history traits including clonal growth, reproductive biology, seed germination and cryopreservation, and genetic diversity. Pitcairnia encholirioides has the phalanx type of clonal growth strategy. Its self-incompatible flowers are successfully pollinated by hummingbirds. However, less than 5% of clonal fragments produced flowers. Seeds can be wind-dispersed, but most of them are dispersed by gravity and fall close to the mother plant. The percentage and speed of germination were significantly affected by different temperatures, water potential, and red:far-red light ratios, although more than 80% of seeds germinated under optimal physiological conditions. The genetic diversity was very low (Hsp = 0.09) and the population was highly structured (ΦST = 0.51). The combination of dispersal mode and environmental conditions seems to be the main factor leading to the rarity of P. encholiroides. Low genetic diversity combined with small population size and low reproductive capacity suggest that the species is highly susceptible to environmental disturbance. Similarly to P. encholiroides, many species from Brazilian inselbergs are restricted to only a few localities. For more widely distributed species, a higher genetic diversity among populations has been consistently detected. The pattern of low gene flow of many species with small distributions highlight the importance of population-based conservation strategies for such taxa the areas of occurrence of which being naturally fragmented at inselberg sites. We discuss some strategies that may help in conservation of such species.  相似文献   

7.
The recognition of a species as invasive is generally accepted when it comes from another continent or even from another country, but requires strong evidences of negative impacts to support control actions when the invasive species comes from another region in the same country. Schyzolobium parahyba – the ‘guapuruvu’, is a Brazilian tree native from the evergreen type of the Atlantic Forest, which has been recorded as invader in a number of remnants of the Seasonally Semideciduous Forest – SSF. We hypothesized that this giant and fast growing invasive tree changes the structure and composition of the understory, thus impairing the forest dynamics. We assessed the invasive population in the whole fragment, and, within the portion invaded, we sampled the regenerating plant community 1) under the largest alien trees, 2) under a native species with similar ecology (Peltophorum dubium), and 3) randomly in the forest. Density, basal area and richness under S. parahyba were remarkably lower than under the equivalent native species or in the understory as a whole. Floristic composition of the plant community was also distinct under S. parahyba, possibly due to increased competition for soil water. Even though the alien species has occupied, as yet, a small proportion of the forest fragment, it dominates the overstory and threatens the regeneration processes under its canopy. In view of our findings, we recommend extirpation of the species from SSF, as well as avoiding cultivation of the species away from its native range.  相似文献   

8.
Hymenaea stigonocarpa, is an endemic tree from the Brazilian cerrado (savannah) and popularly known as jatobá-do-cerrado. The wood of this species is resistant to biodegradation and is used in naval and civil construction. Cuttings from heartwood of this species showed resistance to fungi and termites. In this paper, we report the antitermitic and antioxidant activities of H. stigonocarpa heartwood ethyl acetate extract and its main flavonoids constituents, hultenin (1), taxifolin (2), quercetin (3) and 7-methoxycathequin (4). The structure elucidation of the isolated flavonoids was performed by spectroscopic methods. The ethyl acetate extract possesses highest antitermitic and antioxidant activity when compared with isolated flavonoids.  相似文献   

9.
《Mycoscience》2014,55(3):196-212
The Longibrachiatum Clade of the genus Trichoderma in Japan was examined, among which two new species and three new records are herewith reported. The new species, T. tsugarense and T. kunigamense were isolated from a bed log (cultivation of Lentinula edodes) and volcanic ash soil, respectively. These species are distinguished from closely related species by growth and morphological characteristics and in phylogenetic analysis. Additional species new to Japan were T. ghanense, T. parareesei and T. sinense. The significance of their distribution is discussed. Most species of the Longibrachiatum Clade are tropical rather than temperate in distribution. Their in vitro optimum growth tends to be >35 °C but the optimum temperature for some Japanese species was lower. Some species are endophytes of temperate plant species, some of which are endemic in Japan.  相似文献   

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

11.
Guaco, a native and perennial Brazilian liana, is one of the medicinal plants most widely commercialized in the Brazilian market. The major bioactive compounds in guaco leaves are coumarin and o-coumaric acid, along with kaurene-type diterpenes. Two Mikania species, M. laevigata and M. glomerata, are both treated as guaco in the Brazilian pharmacopeia and are commercialized indiscriminately, although they can be distinguished by the shape of the leaves and by the characteristic coumarin aroma of M. laevigata.We used DNA barcoding, chromosome counting and chemical analysis to study guaco germplasm accessions from collections in 10 Brazilian states. ETS and ITS sequences failed to distinguish most guaco accessions identified as M. glomerata and M. laevigata regardless of geographical origin, suggesting that M. glomerata and M. laevigata are recently diverged species. The chromosome number 2n = 36 was observed in all guaco accessions. In guaco accessions grown under experimental conditions, two chemical phenotypes were found: phenotype G-I, containing moderate coumarin content (644–755 mg/100 g) and high levels of kaurenoic acid (771–881 mg/100 g) and phenotype G-II, containing high levels of coumarin (1123–1309 mg/100 g) and low levels of kaurenoic acid (160–334 mg/100 g). None of the M. glomerata accessions produced coumarin in satisfactory levels (all <100 mg/100 g). Our results suggest that only M. laevigata should be used as guaco. The use of confirmed clonal plant material from controlled sources, such as from a germplasm bank, can guarantee desired pharmaceutical efficacy of this herbal medicine.  相似文献   

12.
The Mekong flows north to south, through six countries in south–east Asia. Many studies have concentrated on fish and fisheries in the Lower Mekong, which has been identified as one of the largest inland fisheries in the world with an incredibly rich diversity of species. In contrast, fish and fisheries in the Upper Mekong (Lancang River) have remained relatively undocumented. In this paper, we synthesized information on freshwater fish biodiversity and fisheries in the Upper Mekong and documented 173 species and subspecies (including 87 endemic species) among 7 orders, 23 families and 100 genera. We divided the Upper Mekong into 17 sub-basins based on Digital Elevation Model (DEM) and then used fish species data to cluster the sub-basins. Four parts (the headwater, the upper reach, the middle reach and the lower reach) and one lake have distinct fish species communities associated with them. There was a linear relationship between fish species (x) and endemic species (y) as y = 0.5464x − 3.2926. Relationship between species number or endemic species number (y) and mean altitude (x) can be described as y = −54.352 ln(x) + 460.79 or y = −30.381 ln(x) + 253.85, respectively. Fisheries kept as about 6,000 t from 1989 to 1998, and then steadily increased to 10,000 t in 2004. We reviewed the overall threats to the Upper Mekong fish and fisheries, and found that hydrological alteration is the largest threat in the basin, followed by over fishing and the introduction of exotic species. In terms of specific river sections, water pollution was the most serious threat to fishes in the upper reach of the Upper Mekong, whilst migratory fishes in the lower reach of the Upper Mekong are seriously threatened by the construction of cascade dams. The Buyuan River and the Nanla River were identified as important feeding and spawning habitats for upstream migrant species and should be considered as a priority for conservation.  相似文献   

13.
Species distribution models (SDMs) provide conservationist with spatial distributions estimations of priority species. Lagothrix flavicauda (Humboldt, 1812), commonly known as the Yellow-tailed Woolly Monkey, is one of the largest primates in the New World. This species is endemic to the montane forests of northern Peru, in the departments of Amazonas, San Martín, Huánuco, Junín, La Libertad, and Loreto at elevation from1,000 to 2,800 m. It is classified as “Critically Endangered” (CR) by the International Union for Conservation of Nature (IUCN) as well as by Peruvian legislation. Furthermore, it is listed in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Research on precise estimates of its potential distribution are scare. Therefore, in this study we modeled the potential distribution area of this species in Peru, the model was generated using the MaxEnt algorithm, along with 80 georeferenced occurrence records and 28 environmental variables. The total distribution (high, moderate, and low) for L. flavicauda is 29,383.3 km2, having 3,480.7 km2 as high potential distribution. In effect, 22.64 % (6,648.49 km2) of the total distribution area of L. flavicauda is found within Natural Protected Areas (NPAs), with the following categories representing the largest areas of distribution: Protected Forests (1,620.41 km2), Regional Conservation Areas (1,976.79 km2), and Private Conservation Areas (1,166.55 km2). After comparing the predicted distribution with the current NPAs system, we identified new priority areas for the conservation of the species. We, therefore, believe that this study will contribute significantly to the conservation of L. flavicauda in Peru.  相似文献   

14.

Background

Although known to be highly endemic in the Amazon regions of Brazil, the presence of cutaneous leishmaniasis (CL) in the subtropical southern part of the country has largely been ignored. This study was conducted to demonstrate CL is emerging in the Brazilian state of Santa Catarina, as well as to characterize the epidemiological profile and Leishmania species involved.

Methodology/Principal Findings

For this cross-sectional study, data from all CL cases from Santa Catarina, Brazil, reported to the Brazilian National Notifiable Diseases Information System from 2001 to 2009 were investigated. Amplification of the kDNA minicircle conserved region followed by restriction fragment length polymorphism (PCR-RFLP) was conducted to screen for Leishmania species present in patient biopsy. Overall, 542 CL cases were reported, with majority resulting from autochthonous transmission (n = 401, 73.99%) and occurring in urban zones (n = 422, 77.86%). Age, gender, zone of residence, origin of case, clinical form and case outcome were found to differ significantly by region. Imported cases were over seven times more likely to relapse (95% CI 2.56–21.09). Mapping of cases revealed new endemic areas in northeastern Santa Catarina with two species present. With the exception of three L. (Leishmania) amazonensis cases (1.20%), majority of PCR positive samples were found to be L. (Viannia) braziliensis (n = 248, 98.80%).

Conclusions/Significance

CL is now endemic in the state of Santa Catarina, Brazil, with case profiles varying significantly by region. L. (V.) braziliensis has been identified as the predominant species in the region.  相似文献   

15.
《Fungal biology》2022,126(8):511-520
Warming and heat waves are predicted by different climate models in the near future in the Pannonian Biogeographical Region (PBR). These climatic effects may have impact on the prevalence and distribution of certain fungal species of this area. In this study the effects of predicted climate scenarios were tested on fungi being endemic or unintentionally introduced by global trade from regions of warm temperate climate. Common fungal species were selected for the study and exposed to heat waves during 7 days according to two climate scenarios: one moderately (RCP 4.5, Tavg = 27 °C, Tmax = 35 °C, RH: 100%) and one strongly pessimistic (RCP 8.5, Tavg = 30 °C, Tmax = 40 °C, RH: 100%) that include predictions for the Central Hungarian Region for July 2050. According to our results, Aspergillus flavus, Aspergillus niger, Aspergillus tubingensis and Fusarium strains introduced from tropical regions tolerated heat waves, unlike Penicillium and Talaromyces spp. and endemic Cladosporium spp. which were unable to grow under the RCP 8.5 treatment. The effects of climate change on fungi raise new issues not only from economic and health perspectives, but also in relation with plant protection and environment. Our results suggest that heat waves driven by climate change promote the colonization and growth of the tested strains of non-native fungi more likely than that of the native ones.  相似文献   

16.
Interspecific hybridization is a primary cause of extensive morphological and chromosomal variation and plays an important role in plant species diversification. However, the role of interploidal hybridization in the formation of hybrid swarms is less clear. Epidendrum encompasses wide variation in chromosome number and lacks strong premating barriers, making the genus a good model for clarifying the role of chromosomes in postzygotic barriers in interploidal hybrids. In this sense, hybrids from the interploidal sympatric zone between E. fulgens (2n = 2x = 24) and E. puniceoluteum (2n = 4x = 56) were analyzed using cytogenetic techniques to elucidate the formation and establishment of interploidal hybrids. Hybrids were not a uniform group: two chromosome numbers were observed, with the variation being a consequence of severe hybrid meiotic abnormalities and backcrossing with E. puniceoluteum. The hybrids were triploids (2n = 3x = 38 and 40) and despite the occurrence of enormous meiotic problems associated with triploidy, the hybrids were able to backcross, producing successful hybrid individuals with broad ecological distributions. In spite of the nonpolyploidization of the hybrid, its formation is a long‐term evolutionary process rather than a product of a recent disturbance, and considering other sympatric zones in Epidendrum, these events could be recurrent.  相似文献   

17.
Danxia landform, a unique type of petrographic geomorphology, sporadically occurs in southern China. There are about 400 rare or threatened plants and animals in this landform, but little information on genetic aspects of these species has been available. Of them, Firmiana danxiaensis is a dominant tree species endemic to Mount Danxia, a typical Danxia landform in northern Guangdong, China. In this study, we examined genetic diversity and population structure of F. danxiaensis, in comparison with two other narrowly distributed Firmiana species, Firmiana hainanensis and Firmiana kwangsiensis, which grow in non-Danxia-landform regions. Nine microsatellite markers were used to investigate genetic diversity and differentiation in a total of 256 individuals from nine populations of F. danxiaensis, three of F. hainanensis, and one of F. kwangsiensis. The results showed that F. danxiaensis had the lowest genetic diversity (HE = 0.364 ± 0.019) among the three species, but weak population structure similar to another Firmiana species (FST = 0.042 and 0.020, respectively). This low genetic diversity observed in F. danxiaensis is possibly due to confined natural distribution range and strong selective pressure in soils of Danxia landform, which may also be true for other endemic species in Danxia landform. For the long term survival of these endemic species, habitat conservation and anthropogenic introduction to similar habitats such as the adjacent Danxia landform areas should be two major strategies.  相似文献   

18.
Gymnocypris dobula is a commercially important fishery species and mostly distributed in the freshwater of Tibetan plateau. In this study, genetic diversity and intraspecific population differentiation were examined by using mitochondrial DNA D-loop sequences in 97 individuals sampled from three localities (Pali, Lasa and Yanghu) in the Tibetan plateau. Two hundred and fourteen polymorphic sites and 50 haplotypes were defined among the three localities. Genetic diversity analysis showed that the highest genetic diversity level was found in Pali population. Phylogenetic relationships analysis results indicated that closer phylogenetic relationships were found between the Yanghu and Lasa populations. Genetic population differentiation analysis indicated that the majority of variation (84.91%) was attributed to variations among populations and the largest differentiation was found between Pali and Lasa localities (Fst = 0.874, Nm = 0.036). Moreover, the historical demographic events were assessed by implementing the mismatch distribution analysis, Fajima's D test and Fu's Fs test. The results indicated that the Pali population had undergone a demographic expansion, possibly within the last 0.163 MYA (Million Years Ago). Our study firstly identified the population genetic structure of the G. dobula, which could be helpful for artificial breeding, fishery stock identification and resource conservation for this species.  相似文献   

19.
Climate change, together with human activities, impacts on natural and human systems on all continents and poses a major threat to biodiversity, especially in environments with a high rate of endemism and where species are profoundly adapted to specific environmental conditions, as is the case of the seasonally dry tropical forests, noticeably the Caatinga, an exclusively Brazilian biome. The objective of this study was to build spatial niche models of five species of Cactaceae (Arrojadoa penicillata, Brasilicereus phaeacanthus, Pereskia aureiflora, Stephanocereus leucostele and Tacinga inamoena) endemic to the Caatinga and with different traits, to evaluate the impact of climate change on their geographical distribution. The species records and environmental variable values were overlaid on a grid of 6818 cells with 0.5° spatial resolution. Niche models were obtained for five types of general circulation models between ocean and atmosphere and 12 different ecological models. The ensemble ecological niche model was calculated at present and projected to past (last glacial maximum – LGM, 21 000; and mid‐Holocene – Hol, 6000 years ago) and future climate conditions (average of 2080), under the effect of climate change, in the greenhouse gas emission scenario RCP4.5. The distribution pattern of the studied species indicates an area with less environmental suitability in the LGM, followed by an expansion that began in the Hol and continued until the present period. In the future (2080), the models predicted a retraction of areas of environmental suitability, in which P. aureiflora and B. phaeacanthus, given their more restricted, marginal habitat and woody habit, present a great risk of extinction, whilst S. leucostele, A. penicillata and T. inamoena present a smaller reduction in suitable area, partly reflecting their spreading, less woody habit. Regional conservation actions for Cactaceae species and their habitat need to take these findings into account if we are to ensure the survival of these species.  相似文献   

20.
Nepenthes lavicola Wistuba & Rischer (Nepenthaceae) is a pitcher plant endemic to the northern tip of Sumatra Island, Indonesia. Due to its narrow geographic distribution and threats from a volcanic eruption and illegal harvesting by pitcher plant hunters, N. lavicola was assessed as Critically Endangered (CR) under criteria B1 + 2c of the IUCN Red List in 2000. Here, we report two new additional locations of N. lavicola in Aceh Tengah Regency, along with the population data and habitat characteristics of the species in each location. Based on our findings, we propose Endangered (EN) B1ab(iii) + 2ab(iii),C2a(i) as the new conservation status of N. lavicola. The new proposed status has a lower category of threat than the current status of the species. Nevertheless, under the new category, N. lavicola is still considered to be facing a very high risk of extinction in the wild. Comprehensive and immediate conservation actions are required to halt the species from extinction.  相似文献   

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