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1.
中国种子植物内生真菌资源及菌植协同进化   总被引:4,自引:0,他引:4  
综述了中国种子植物内生真菌资源研究概况,比较了裸子植物和被子植物内生真菌种类,它们都具有肉座菌目(Hypocreales),粪壳菌目(Sordariales),散囊菌目(Eurotiales),毛霉目(Mucorales)及不产孢类(Myceliasterilia)内生真菌。裸子植物内生真菌涉及52个属,既包括高等的子囊菌和担子菌,也包括低等的卵菌(Oomycetes)和接合菌(Zygomycetes)类。被子植物涉及60个属,主要为高等的子囊菌(Ascomycetes)和担子菌(Basidiomycetes),低等的卵菌和接合菌报道很少。双子叶植物涉及40个属,单子叶植物内生真菌涉及30个属,两类被子植物所报道的内生真菌只有11个属相同。裸子植物与双子叶植物内生真菌相似程度较高,都具有炭角菌目(Xylariales)、格孢腔菌目(Pleosporales)、柔膜菌目(Helotiales)和白粉菌目(Erysiphales),刺盘孢菌属(Colletotrichum)、拟茎点霉属(Phomopsis)、枝孢霉属(Cladosporium)、地霉属(Geotrichum)等内真菌,共20个属相同。各类种子植物具有自己独特的一些内生真菌。还对植物与其内生真菌的协同进化关系进行了分析。  相似文献   

2.
The characteristics of the contents of 20 elements (Al, Fe, Mn, Ca, Mg, K, S, Si, P, Cd, Cu, Zn, Ti, Ni, Sr, Mo, Na, B, Cr, V) in 16 plant species collected from the Three Gorges Region in China were investigated. The average contents of Ca, K and Mg were higher than 1 000 μg·g-1, that of Al, P, Si, Fe, S and Mn ranged between 100—1 000 μg·g-1 and Ti, Cu, Ni, Cr, Mo, Cd and V were less than 10 μg·g- 1. The level of Na content was less than that of the reported. The main character of the element contents was of the Ca> K type. The contents of P, S, Ca and K in different plant samples showed a normal distribution pattern, while Al and Mn showed a elements lognormal distribution pattern. Plant species differed greatly in the element contents. On analyzing the coefficient of variation (C. V., % ), Al, Mn, Mg, Ni, Sr and Fe had higher C.V., while the C.V. of K, S, P, Cr, Cd and Cu was less than 60%, and Cu had the lowest C.V. The correlations between Al and Fe, Al and Ti, Al and Cr, A1 and V, Cd and Sr, Cd and Mo, Fe and V, Zn and Cr, Ni and Sr, Mg and Ni, Mo and Sr, Ca and Sr, Cr and Mo, Na and Mg, Na and P, P and S were statistically significant in different plant species. The classification of the 16 plant species and 20 dements by two-way indicator species analysis (TWINSPAN) method may suggest the difference in dement contents of the different plant species.  相似文献   

3.
高程  郭良栋 《生物多样性》2022,30(10):22429-23168
微生物主要包括细菌、真菌、古菌、病毒等类群, 是地球上出现时间最早、分布最广泛、个体数量最多, 以及物种和基因多样性十分丰富的生物类群。为了适应各种生境, 微生物衍生出腐生、寄生、共生等多样的生存策略, 在生物地球化学循环、生态系统演替与稳定性、环境修复以及人类健康等方面发挥着重要作用。传统的微生物监测方法限制了我们对微生物多样性的认知; 但是, 近年来高通量测序技术和生物信息学的发展极大推动了微生物多样性的研究进展。本文概述了近年来在微生物多样性分布格局与维持、群落构建以及功能属性多样性的最新进展; 总结分析了细菌、古菌、真菌的多样性纬度分布格局及其驱动因子, 选择、扩散、成种、漂变等过程对细菌、古菌、真菌的群落构建的贡献, 以及细菌和真菌的形态、生理生化、生长繁殖、扩散、基因组等功能性状的多样性; 提出了未来微生物多样性研究的重要领域: 环境宏真菌组研究, 微生物多样性与生态系统多功能性的关系研究, 以及微生物互作网络的生态功能研究。  相似文献   

4.
ABSTRACT

This article synthesizes knowledge on the role of relationships and key macroand micro-contexts - poverty, racism, families, communities, schools, and peers - in supporting and/or undermining the healthy development of children and youth, using a relational developmental systems framework. Relationships with parents, siblings, peers, caregivers, and teachers are explored in the context of early care and childhood settings, schools, classrooms, and school-based interventions. Additional contextual factors include; chronic stress, institutionalized racism, stereotype threat, and racial identity. A companion article focuses on how the human brain develops, and the major constructs that define human development, the constructive nature of development, and the opportunities for resilience. Human development occurs through reciprocal coactions between the individual and their contexts and culture, with relationships as the key drivers. Relationships and contexts, along with how children appraise and interpret them, can be risks and assets for healthy learning and development, and their influence can be seen across generations and can produce intra- as well as intergenerational assets and risks. This knowledge about the individual’s responsiveness to context and experience has both positive and negative implications across early childhood, adolescence and into adulthood. Sensitive periods for brain growth and development are considered within the contextual factors that influence development including; parental responsiveness and attunement, intentional skill development, mindfulness, reciprocal interactions, adversity, trauma, and enriching opportunities. The accumulated knowledge on human development and the power of context and culture can inform child-serving systems that support positive adaptations, resilience, learning, health, and well-being.  相似文献   

5.
Leccinum scabrum sporocarps and associated topsoils from two areas in Poland have been characterized for contents and bioconcentration potential of Ag, Al, Ba, Ca, Cd, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sr and Zn. Topsoil and fruitbody element composition varied between the two study sites, most likely as a result of local soil geochemistry. Element content of the labile fraction in topsoil from both sites followed the ‘pseudo‐total’ fraction and median values (mg kg?1 dry matter) were: K 380 and 340, Mg 760 and 840, P 1100 and 920, Al 3800 and 8100, Ag 0.31 and 0.28, Ba 28 and 37, Ca 920 and 790, Cd 0.23 and 0.23, Co 2.0 and 1.7, Cu 3.2 and 3.6, Fe 2800 and 6300, Mn 280 and 180, Na 99 and 110, Ni 7.8 and 8.8, Pb 12 and 18, Rb 1.3 and 2.1, Sr 4.8 and 4.0 and Zn 22 and 19, respectively. Only for some elements such as K, Mg, Al, Ag, Ca, Co, Mn, Na, Ni, Sr and Zn we found concentration differences between the two study sites for the caps of sporocarps. With the exception of Al, Mn, Na and Pb, stipes showed a similar tendency. Caps had a higher concentration of K, Rb, P, Mg, Al, Ag, Cu, Fe, Zn, Cd, Pb and Ni compared to stipes, while Na, Ba and Sr contents were higher in stipes. The comparison of soil and fruitbody concentrations indicates that L. scabrum bioconcentrate some elements while others are bioexcluded.  相似文献   

6.
Plasma levels of testosterone (T), 17-β-estradiol (E2), progesterone (P4), dehydroepiandrosterone (DHEA), corticosterone (B), thyroxine (T4) and triiodothyronine (T3) were monitored during postnuptial and the prenuptial molt in domestic goose (Anser anser domesticus) in both sexes. 1. At the beginning of postnuptial molt (when the old, worn dawny-, and cover feathers' loss starts) in ganders, the levels of T, E2, P4 decrease while DHEA and B significantly increase. The elevated levels of T4 and low T3 concentrations characteristic of the last phase of the reproduction, remain unchanged. In layers, similar changes were observed, however, B decreases. 2. In the early phase of outgrowth of wing and cover feathers, plasma levels of T, E2 and P4 are low. Elevated B, DHEA and T4 concentrations decrease in ganders, while in layers DHEA increases and B and T4 levels remain unchanged. T3 increases in both sexes. 3. The subsequent intensive outgrowth period of wing- and cover feathers both in ganders and in layers is characterized by very low levels of T, E2, DHEA and T4, but P4 increased, and T3 concentration remain high. 4. At the end of postnuptial molt - when the outgrowth of dawny, cover-, and wing feathers stops - very low T, E2, P4, DHEA and T4 levels and and high T3 plasma levels were found in both sexes. Fast increase of plasma B was detected in ganders, while in geese, B concentration remain high. 5. During prenuptial molting (outgrowth of contour and tail feathers) low E2, P4 and T4, increasing T and DHEA, but very high T3 and B plasma concentration were measured in ganders. In layers, very low T, E2, P4, DHEA and T4 levels, and very high B and T3 levels were found. 6. At the beginning of the fall-winter sexual repose (postmolting stage) T, E2, P4, DHEA and T4 levels increase, T3 and B declines in both sexes. 7. In the subsequent phase of fall-winter period (preparatory stage) there is a further increase in T, P4 and T4, a fast increase of B and a decrease of E2, DHEA and T3 in ganders. In layers, T, P4 and DHEA decrease, B increases and the T4 and T3 do not change. 8. At the beginning of reproduction high T level, unchanged DHEA, slightly declined P4, and decreased E2, T4, T3 and a strong decline of B concentrations occur in ganders. In layers, T is further increased, E2 and P4 shows high levels, and, at the same time DHEA and T3 remain unchanged, while B and T4 decrease.  相似文献   

7.
新建果园几种作物间种模式生态系统结构及功能研究   总被引:3,自引:2,他引:1  
从荒坡地新建果园10多种农作物间种模式中筛选出5种优化模式,分析和评价了各种种植模式的生态系统的结构和功能.结果表明,随着重复种植的增加,5种间种模式土壤有机质年增加5%一20%,全氮年增加7%一40%,全磷年增加8%一70%,全钾年增加15%一80%;水土保持最好的是花生-秋大豆、春大豆-秋大豆,其次为西红柿-白菜、辣椒-西红柿和早稻-红萝卜,土壤平均侵蚀量和地表径流量与对照相比分别降低44.19%、38.24%、39.52%、37.56%、37.30%和22.40%、9.28%、24.11%、21.60%、15.93%;在5种模式中,生物量最高的是辣椒—西红柿,年均达到100276kg.hm^-2,其次是花生-秋大豆,年均达到77026kg.hm^-2;而生产力最高的是花生—秋大豆,达到15619kg.hm^-2,其次是西红柿—白菜,为15394kg.hm^-2;投能效率最高的是辣椒—西红柿,年均达到3.06,其次为西红柿—白菜、花生—秋大豆、春大豆—秋大豆、早稻-红萝卜,分别为2.16、2.15、2.06和0.71.同时,有机、无机能输入效应表明,以生物能为主源输入进行转化利用太阳光能和水土资源,维护了果园生态系统的能量盈余,生态效益较高.  相似文献   

8.
Because of some catastrophic events which occurred in Mexico during the 1980 decade, the utilization of "tepescohuite" bark against skin wounds and burns was popularized. The media manipulated the lack of available information about its medical properties and gave erroneous information to the society propagating a lot of myths. Therefore, the aim of this paper is to determine its taxonomic identity and to study the distribution, bark and wood anatomy of this species, and to determine its actual and historic uses, and the compilation of the information about bark pharmacology and toxicity. Its taxonomic identity is established as Mimosa tenuiflora (Willd.) Poir. (Fabaceae-Mimosoideae). It blooms and fructifies from November to June, occurring in Mexico (the states of Oaxaca and Chiapas), Guatemala, Honduras, El Salvador, Nicaragua, Panama, Colombia, Venezuela and Brazil, at altitudes of 0-1110 (-1520) m. In Mexico, it is found in dry forests, thorny thickets, Pinus and Pinus-Quercus forests, and in M. tenuiflora pure thickets, along roads and in resting or abandoned culture lands. This species has an aggregate distribution in the forests and a uniform one in the thickets. It presents a mean density of 9 individuals per m2, with 0.45 of frequency per quadrat and 1.69 m2 of mean coverture, and it has a wide range of tolerance to climatic and edaphic factors, confirming their invasive character. Regionally, the wood is used as fuel and fence construction, and against skin wounds and burns (bark tea, powder and/or ointment), and diverse products, such as shampoos, creams, capsules, soaps, etc., are commercialized. The bark is wrinkled, reddish-brown to grey, fibrous texture, 0.5-1.5 mm thick, resinous and with an astringent odor and flavor, and with a great quantity of tannins. The wood presents extremely short vessel elements, with alternate areolate punctuations, and simple perforated plates, vasicentric axial parenchima, confluent stripes, uniseriated rays, extremely short, fine and very short libriform fibres. The bark contains tannins, saponins, an alkaloide fraction, lipids, phytosterols, glucosides, xylose, rhamnose, arabinose, lupeol, methoxychalcones, and kukulkanins.  相似文献   

9.
Three dermatan sulfates (DS18, DS28, and DS35) were isolated from women's skin of ages 19 +/- 2.5, 35 +/- 3.5, 47 +/- 1.7, 60 +/- 0.8, and 75 +/- 5 years. They sequentially precipitated with 18, 28, and 35% ethanol. Their sulfate content was: 23.5, 25.3, and 29.0% (w/w) for DS18 at ages 19-35, 47, and 60 years, respectively; 29.0, 24.0, and 18.8% for DS28; and 18.0, 20.0, and 20.6% for DS35 at ages 19-47, 60, and 75 years, respectively. Both DS18 and DS28 decreased, respectively, from 0.030% (of wet-skin weight) to traces at age 75, and from 0.020 to 0.010% at 60 years. At age 75, DS28 apparently increased by 30%. The DS35 values (traces-0.006%) had no age-related trend. Hyaluronic acid (HA) precipitated with 45% ethanol, was 0.030% of skin-weight at ages 19-47, and decreased to 0.015 and 0.007% at 60 and 75 years, respectively. Its electrophoretic mobility was slower at age 47. In the oldest group, i.r. spectra of HA and DS35 displayed no bands at 1650-1600, 1380, and 1320 cm-1, and a new band at 1560 cm-1. Moreover, ninhydrin-positive material of HA and DS35 increased by 75 and 95%, respectively, and the reducing GlcNAc content of HA decreased. These data showed three chemically different dermatan sulfates (two of which were preponderant) and N-deacetylation of HA and DS35 of the oldest group. After age 47, total DS and HA considerably decreased, DS18 and DS35 were oversulfated, and DS28 became undersulfated with aging.  相似文献   

10.
11.
This study examines the extent to which various ethnic-immigrant and US-born groups differ in their risks of all-cause and cause-specific mortality, morbidity, and health behaviors. Using data from the National Longitudinal Mortality Study, 1979-1989, we estimated, for major US racial and ethnic groups, mortality risks of immigrants relative to those of the US-born. The Cox regression model was used to adjust mortality differentials by age, sex, marital status, rural/urban residence, education, and family income. Logistic regression was fitted to the National Health Interview Survey data to determine whether health status and behaviors vary among ethnic-immigrant groups and by length of US residence. Compared with US-born whites of equivalent socioeconomic and demographic background, foreign-born blacks, Hispanics, and Asians/Pacific Islanders (APIs), US-born APIs, US-born Hispanics, and foreign-born whites had, respectively, 48%, 45%, 43%, 32%, 26%, and 16% lower mortality risks. While American Indians did not differ significantly from US-born whites, US-born blacks had an 8% higher mortality risk. Black and Hispanic immigrants experienced, respectively, 52% and 26% lower mortality risks than their US-born counterparts. Considerable differentials were also found in mortality for cancer, cardiovascular, respiratory, infectious disease, and injury, and in morbidity and health behaviors, with API and Hispanic immigrants generally experiencing the lowest risks. Consistent with the acculturation hypothesis, immigrants' risks of smoking, obesity, hypertension, and chronic condition, although substantially lower than those for the US-born, increased with increasing length of US residence. Given the substantial nativity differences in health status and mortality, future waves of immigrants of diverse ethnic and cultural backgrounds will likely have a sizeable impact on the overall health, disease, and mortality patterns in the United States.  相似文献   

12.
This paper aggregates and compares findings on 300 groups of women studied in different parts of the world. Variables considered are stature, sitting height, head width and length, face width and height, shoulder and hip widths, and limb girths. Most of the groups were measured between 1950 and 1965. Mean stature approximates 137 cm to 139 cm on Bambuti women of Africa, Asai women of New Guinea, and Sierra de Parija women of South America. Means are near 143 cm for Pahira and Telefolmin women; 148 cm for Bundi, Quechua, and Vietnamese women; 154 cm for Ethiopian and Japanese women; and 159 cm for Coniagui, Italian, Jamaica Negroid, Polish, and Russian women. Groups taller than 162 cm include Amerind women of the Blackfeet tribe; European women of German, Norwegian, Swedish, and Swiss descent; and United States women of northwest European ancestry. The body stem component of stature is relatively short in Australian aborigines and women of several Negroid and Amerind tribes; relatively long in Japanese and Quechua women; and intermediate in women of India, Taiwan aborigines, and United States Caucasoid women. In mean head width, Apache women exceed Pahira women by 2.4 cm, or 18%. In head length, Easter Island natives average 2.0 cm, or 12% longer than Paiwan women of Taiwan. Means for biiliocristal diameter are below or near 24 cm on Bujeba, Hutu, Quechua, Shirisna, Tutsi, and Yecuana women, and above 28 cm on Basque, French, Hungarian, Sicilian, and United States Caucasoid women. For biacromial diameter, means are near 30 cm on Sinhalese women, and near 36 cm on several groups of European women.  相似文献   

13.
Polyamines extracted from whole bodies of four springtails, Tomocerus ishibashii, Hypogastrura communis, Sinella cruviseta and Folsomia candida, a bristletail, Pedetontus nipponicus, and two silverfish, Lepisma saccharina and Thermobia domestica, were analyzed by high-performance liquid chromatography and gas chromatography. All seven apterous insect species contained putrescine, cadaverine and spermidine as the common major polyamines, detected at the level of micromol/g wet mass. T. ishibashii also contained spermine, S. cruviseta contained norspermidine and norspermine and H. communis, F. candida and P. nipponicus contained diaminopropane, norspermidine and norspermine, as minor polyamines above the detection limit (0.01 micromol/g wet mass). The occurrence of diaminopropane, norspermidine, norspermine, spermine and thermospermine was confirmed in L. saccharina and T. domestica. The novel polyamines norspermidine, norspermine and thermospermine, widespread in higher insects, were also distributed within the primitive apterygotan insects.  相似文献   

14.
Love is a complex neurobiological phenomenon, relying on trust, belief, pleasure and reward activities within the brain, i.e., limbic processes. These processes critically involve oxytocin, vasopressin, dopamine, and serotonergic signaling. Moreover, endorphin and endogenous morphinergic mechanisms, coupled to nitric oxide autoregulatory pathways, play a role. Naturally rewarding or pleasurable activities are necessary for survival and appetitive motivation, usually governing beneficial biological behaviors like eating, sex, and reproduction. Yet, a broad basis of common signaling and beneficial neurobiological features exists with connection to the love concept, thereby combining physiological aspects related to maternal, romantic or sexual love and attachment with other healthy activities or neurobiological states. Medical practice can make use of this concept, i.e., mind/body or integrative medicine. Thus, love, pleasure, and lust have a stress-reducing and health-promoting potential, since they carry the ability to heal or facilitate beneficial motivation and behavior. In addition, love and pleasure ensure the survival of individuals and their species. After all, love is a joyful and useful activity that encompasses wellness and feelings of well-being.  相似文献   

15.
沙漠化对科尔沁沙质草地生态系统碳氮储量的影响   总被引:1,自引:0,他引:1  
通过野外调查,研究了沙漠化对科尔沁沙质草地生态系统碳、氮储量的影响.结果表明:沙漠化对草地碳、氮含量和储量具有显著影响,随着草地沙漠化的进程,草地碳、氮含量和储量明显下降.与非沙漠化草地相比,轻度、中度、重度和严重沙漠化草地0~100cm深土壤有机碳和全氮含量分别下降了56.06%和48.72%、78.43%和74.36%、88.95%和84.62%、91.64%和84.62%,植物组分中的碳、氮含量分别下降了8.61%和6.43%、0.05%和25.71%、2.58%和27.14%、8.61%和27.86%;轻度、中度、重度和严重沙漠化草地地上植物组分中的碳、氮储量分别下降了25.08%和27.62%、30.90%和46.55%、73.84%和80.62%、90.89%和87.31%,0~100cm深地下植物组分中碳和全氮储量分别下降了50.95%和43.38%、75.19%和71.04%、86.76%和81.48%、91.17%和83.17%.2000年科尔沁沙地沙漠化草地总面积为30152.7km2,因沙漠化损失的碳、氮总储量高达107.53和9.97Mt.草地碳、氮含量的下降主要源于风蚀过程中土壤细颗粒的损失.土壤的粗化和贫瘠化最终导致了植物和凋落物中碳、氮储量的明显下降.  相似文献   

16.
Anthocyanins from tart cherries, Prunus cerasus L. (Rosaceae) cv. Balaton and Montmorency; sweet cherries, Prunus avium L. (Rosaceae); bilberries, Vaccinum myrtillus L. (Ericaceae); blackberries, Rubus sp. (Rosaceae); blueberries var. Jersey, Vaccinium corymbosum L. (Ericaceae); cranberries var. Early Black, Vaccinium macrocarpon Ait. (Ericaceae); elderberries, Sambucus canadensis (Caprifoliaceae); raspberries, Rubus idaeus (Rosaceae); and strawberries var. Honeoye, Fragaria x ananassa Duch. (Rosaceae), were investigated for cyclooxygenase inhibitory and antioxidant activities. The presence and levels of cyanidin-3-glucosylrutinoside 1 and cyanidin-3-rutinoside 2 were determined in the fruits using HPLC. The antioxidant activity of anthocyanins from cherries was comparable to the commercial antioxidants, tert-butylhydroquinone, butylated hydroxytoluene and butylated hydroxyanisole, and superior to vitamin E, at a test concentration of 125 microg/ml. Anthocyanins from raspberries and sweet cherries demonstrated 45% and 47% cyclooxygenase-I and cyclooxygenase-II inhibitory activities, respectively, when assayed at 125 microg/ml. The cyclooxygenase inhibitory activities of anthocyanins from these fruits were comparable to those of ibuprofen and naproxen at 10 microM concentrations. Anthocyanins 1 and 2 are present in both cherries and raspberry. The yields of pure anthocyanins 1 and 2 in 100 g Balaton and Montmorency tart cherries, sweet cherries and raspberries were 21, 16.5; 11, 5; 4.95, 21; and 4.65, 13.5 mg, respectively. Fresh blackberries and strawberries contained only anthocyanin 2 in yields of 24 and 22.5 mg/100 g, respectively. Anthocyanins 1 and 2 were not found in bilberries, blueberries, cranberries or elderberries.  相似文献   

17.
At high osmotic pressures, mammalian kidney medulla, heart, lens, and brain utilize organic osmolytes to regulate cell volume. However the types and proportions of these solutes vary among tissues in patterns and for non-osmotic roles not fully elucidated. To clarify these, we analyzed osmolyte-type solute contents in rat tissues at 7 and 2 days prenatal and at 0, 7, 14, 21 (weaning), 35 (juvenile) and 77 (adult) days postnatal. Placentas were dominated by betaine, taurine, and creatine, which decreased between the prenatal times. Fetuses were dominated by glutamate and taurine, which increased between the times. In cerebrum, hindbrain and diencephalon, taurine dominated at early stages, but dropped after postnatal day 7, while myo-inositol, glutamine, creatine and glutamate increased after birth, with the latter two dominating in adults. In olfactory bulb, taurine content declined gradually with age and was equal to glutamate in adults. In all brain regions, glycerophosphorylcholine (GPC) reached a peak in juveniles. In postnatal renal medulla, urea, sodium, GPC, betaine, and taurine increased sharply at day 21. Thereafter, most increased, but taurine decreased. In heart, taurine dominated, and increased with age along with creatine and glutamine, while glutamate decreased after postnatal day 7. In lens, taurine dominated and declined in adults. These patterns are discussed in light of hypotheses on non-osmotic and pathological roles of these solutes.  相似文献   

18.
Phylogenetic relationships of the pantropical family Ebenaceae s.l. were investigated using plastid DNA sequence data from six regions: atpB, matK, ndhF, trnK intron, trnL intron, and trnL-trnF spacer. Sampling included representatives of all currently recognized genera of Ebenaceae, Diospyros, Euclea, and Lissocarpa, and nearly all taxa that were previously recognized at the generic level, e.g., Cargillia, Gunisanthus, Maba, Macreightia, Royena, and Tetraclis. Our results strongly support monophyly of Ebenaceae s.l. and demonstrate that the previous infrafamilar classifications of the family do not circumscribe monophyletic groups. A new infrafamilial classification based on a phylogenetic approach is proposed here and consists of two subfamilies, Lissocarpoideae and Ebenoideae, and four genera, Lissocarpa, Euclea, Royena, and Diospyros. Relationships and potential synapomorphic characters are discussed and summarized. This study supports a western Gondwanan origin of family and indicates that both vicariant and long-distance dispersal events played an important role in attaining current distributions.  相似文献   

19.
The increasing loads of anthropogenic pollutants, compounded with climate change events, are likely to induce environmental changes in many wetlands with impacts on the native microinvertebrates and pathogens causing increased occurrence of water-borne diseases, which affect millions of people each year. In wetlands bacterial pathogens are actively preyed on by many protozoa and filter-feeding organisms but this predation can be compensated by the nourishment and protection offered by certain microinvertebrates, acting as hosts, e.g., chitinous rotifers, copepods and cladocerans. The complex interactions of ecological, biological, and genetic components mediate disease-causing organisms to exploit microinvertebrate hosts to occupy diverse niches, obtain nutrition, and withstand physico-chemical stresses. The persistence of the human pathogens in wetlands is often enabled by their association with microinvertebrates and also depends on their quorum sensing mediated colonization, biofilm formation, switching into dormant stage, and horizontal transfer of adaptive genes. The symbiosis with microinvertebrates is facilitated by the pathogen’s immune evasion and fitness factors, e.g., Type-IV pili, capsular-polysaccharides, nutrient transportation, virulence and binding proteins, proteases, chitinases, and secretion systems. Spatio-temporal variation in the population of copepods and aquatic eggs/larvae of mosquitoes and midge flies, which act as vectors, can influence the outbreaks of cholera, diarrhea, malaria, dengue, filariasis and drucunculiasis. Changes in climatic factors (temperature, salinity, cyclones, rainfall, etc.) and anthropogenic pollutions (sewage, fertilizer and insecticide) may modify the abundance and biodiversity of microinvertebrates, and thus possibly exacerbate the persistence and dispersal of water-borne pathogens. Thus there is a need to adopt ecohydrological and eco-friendly interventions for managing wetlands while conserving them.  相似文献   

20.
自然保护区生态旅游对野生动物的影响   总被引:17,自引:2,他引:15  
马建章  程鲲 《生态学报》2008,28(6):2818-2818~2827
目前中国的很多自然保护区开展了生态旅游,但这类活动对野生动物的影响研究却十分薄弱,因此十分有必要在介绍欧美、澳洲学者的研究进展基础上,针对我国的研究现状,提出该领域的研究方向、监测和管理策略.自然保护区的生态旅游活动主要有野生动物观赏、徒步行走、摄影、野外宿营、山地车或雪地车、电动或机动艇游湖、溪涧漂流、环境教育、社区访问等,旅游活动类型、范围、强度、时空分布等是影响对野生动物干扰大小的主要因素.生态旅游对野生动物的影响包括直接影响(个体的行为反应和生理指标改变、繁殖力降低、种群分布和物种组成的改变等)和间接影响(生境破坏、外来种散布和环境污染等).国外生态旅游对鸟类的影响研究较多,主要集中鸟类的惊飞反应、取食、能量消耗、繁殖等方面;对兽类影响的研究主要集中在行为、生理指标改变、种群数量等方面.我国未来的研究应注重收集基础性研究数据和深入探讨一些理论与应用问题,要运用多种技术手段对自然保护区野生动物的行为、生理、种群动态、物种多样性、生境质量、游客的时空分布、态度和行为等进行长期监测,而后将其结果应用到野生动物、生境以及游客的管理决策中去.另外,研究中应重视自然科学和社会科学的多学科交叉融合.  相似文献   

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