56 resultados para diverse nature
Resumo:
The diet and feeding ecology of a wild subpopulation of black-and-white snub-nosed monkeys (Rhinopithecus bieti) were studied at Xiaochangdu in Honglaxueshan Nature Reserve, Tibet. This region is climatologically harsher than any other inhabited by non-human primates. Black-and-white snub-nosed monkeys fed on 48 parts of 25 plant species, at least three species of lichens and seven species of invertebrates. The number of food items exploited varied markedly among seasons, with dietary diversity being greatest in spring and summer. In winter, black-and-white snub-nosed monkeys had to subsist on fallback foods such as dried grass and bark. Ubiquitous lichens formed a major dietary constituent throughout the year, contributing about 75% of feeding records. Even though lichens act as a staple, our findings signify that the monkeys at Xiaochangdu prefer feeding on foliage, which is higher in protein content than the former. We provide evidence that black-and-white snub-nosed monkeys are able to cope with an array of food items other than lichens and hence can be regarded as feeding generalists. We discuss the results with reference to previous studies on other subpopulations living in habitats that are floristically more diverse and offer more plant food items than the marginal habitat at Xiaochangdu.
Resumo:
Gao-Yan Li, Xu-Zhen Wang, Ya-Hui Zhao, Jie Zhang, Chun-Guang Zhang, and Shun-Ping He (2009) Speciation and phylogeography of Opsariichthys bidens (Pisces: Cypriniformes: Cyprinidae) in China: analysis of the cytochrome b gene of mtDNA from diverse populations. Zoological Studies 48(4): 569-583. The cyprinid fish Opsariichthys bidens Gunther is distributed in all major river systems of continental East Asia, and represents an attractive model for phylogeographic studies among cyprinid species or within a given species. In this study, we investigated the phylogeographic and demographic history of this species, using partial sequences of the cytochrome (cyt) b gene in mitochondrial (mt)DNA. Fish samples were collected from almost all major river systems where O. bidens is distributed in China. Sequence analysis showed remarkably high polymorphism, with 125 haplotypes in the 234 specimens examined, and with 89.8% of haplotypes occurring in only 1 specimen. A neutrality test indicated that some groups were not at mutation-drift equilibrium, suggesting a past population expansion. These results were supported by a mismatch distribution analysis. Based on our analysis, O. bidens consists of 4 groups belonging to 2 clades. The divergence time of the 2 clades was estimated to be 11.06-8.04 my. This value corresponds to the time of the 2nd uplift of the Qinghai-Tibet Plateau, the emergence of the East Asian monsoon, and the Epoch-6 Event. A two species scheme is proposed. http://zoolstud.sinica.edu.tw/Journals/48.4/569.pdf
Resumo:
Perfluorooctane sulfonate (PFOS) is widely distributed and persistent in the environment and in wildlife, and it has the potential for developmental toxicity. However, the molecular mechanisms that lead to these toxic effects are not well known. In the present study, proteomic analysis has been performed to investigate the proteins that are differentially expressed in zebrafish embryos exposed to 0.5 mg/l PFOS until 192 h postfertilization. Two-dimensional electrophoresis coupled with mass spectrometry was employed to detect and identify the protein profiles. The analysis revealed that 69 proteins showed altered expression in the treatment group compared to the control group with either increase or decrease in expression levels (more than twofold difference). Of the 69 spots corresponding to the proteins with altered expression, 38 were selected and subjected to matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (TOF/TOF) analysis; 18 proteins were identified in this analysis. These proteins can be categorized into diverse functional classes such as detoxification, energy metabolism, lipid transport/steroid metabolic process, cell structure, signal transduction, and apoptosis. Overall, proteomic analysis using zebrafish embryos serves as an in vivo model in environmental risk assessment and provides insight into the molecular events in PFOS-induced developmental toxicity.
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Seven species of the marine enchytraeid genus Grania Southern, 1913 are described from sediments sampled during the 2003 International Workshop on the Marine Flora and Fauna of Esperance Bay and the Recherche Archipelago, on the southern coast of Western Australia. Two species are new to science, the euryhaline Tasmanian G. dolichura Rota and Erseus, 2000 represents a new record for the state, and the remaining four species were known from other parts of Western Australia. Grania quaerens sp. n. is recognized by having a high chaetal index (= 5 short chaetal foot), small coelomocytes, penial apparati with long whip-like terminal stylets, conspicuous spermathecae with ectally bulbous ducts, and ectally granulated ampullae housing sperm rings in their ental region. Grania sperantia sp. n. is readily distinguishable by the complete lack of lateral chaetae, a multiple-banded pattern of the clitellum, extremely long sperm funnels, and the intrasegmental location of the spermathecal pores. The latter new species and four others in the collection (G. bykane Coates, 1990, G. crassiducta Coates, 1990, G. dolichura, and G. ersei Coates, 1990) are remarkable in possessing the head organ, a sensory structure unique to Grania that was not noted previously in Western Australian species. When considering the whole genus, the geographic pattern of the head organ appears southern-centred: of the 17 species of Grania reported to possess it, as many as 13 inhabit the southern latitudes. The seventh species of the Esperance collection, G. vacivasa Coates and Stacey, 1993, is notable for the kind of items found in its gut and the unusual appearance of its pygidium.
Resumo:
Two thousand four hundred fifty-eight fish comprised of 53 species were captured in the Danjiangkou Reservoir, in the northwestern part of Hubei Province, central China during 2004, to examine Camallanus cotti infections. We found that 19 cypriniform, 3 siluriforme, and 4 perciforme fishes were infected by the nematode. Our study revealed the species, Hemiculter bleekeri bleekeri, Culter oxycephaloide, Pseudolaubuca sinensis, Acanthobrama simony, Mylopharyngodon piceus, Ctenopharyngodon idella, Gnathopogon imberbis, G. argentatus, Saurogobio dabryi, S. dumerili, Gobiobotia ichangensis, Liobagrus marginatoides, and Ctenogobius shennongensis as new hosts of the worm. The number and range of fish host species found in this survey were much greater than any of the previous investigations. The mean prevalence, prevalence, mean abundance, and intensity of infection varied in different fish species, indicating a possible host preference. Moreover, we suggest that this nematode is a native parasite of cypriniform fishes in China, perhaps initially in the reaches of the Yangtze River.
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Ecological survey of macrozoobenthos assemblages was carried out at 32 sites in the East Dongting Nature Reserve, located in the northern region of the East Dongting Lake in the middle basin of the Yangtze River, China. All total 51 taxa including 18 oligochaetes, 15 mollusks, 14 insects and four other animals were recorded. Mollusks composed the dominant group and accounted for more than 70% of the total abundance. Assemblages were composed mainly of scrapers (66.7%) and collector-gatherers (nearly 20%), and to a lesser extent collector-filterers (roughly 12%), predators (ca. 7%), and shredders (ca. 6%). Two-way indicator species analysis, detrended correspondence, and canonical correspondence analysis (CCA) were employed to identify the relationships between macrozoobenthos assemblages and environmental variables. Thirty-two sites were separated into four site groups based on composition and relative abundance of benthic macroinvertebrates. CCA detected that water depth, pH, conductivity, SiO2, total nitrogen, total phosphorus, alkalinity, hardness, and Ca2+, were significant environmental factors influencing the pattern of macozoobenthos. In this minimal subset, water depth, pH, alkalinity and hardness were the most influential variables.
Resumo:
Misfit defects in a 3C-SiC/Si (001) interface were investigated using a 200 kV high-resolution electron microscope with a point resolution of 0.194 nm. The [110] high-resolution electron microscopic images that do not directly reflect the crystal structure were transformed into the structure map through image deconvolution. Based on this analysis, four types of misfit dislocations at the 3C-SiC/Si (001) interface were determined. In turn, the strain relaxation mechanism was clarified through the generation of grow-in perfect misfit dislocations (including 90 degrees Lomer dislocations and 60 degrees shuffle dislocations) and 90 partial dislocations associated with stacking faults. (C) 2009 American Institute of Physics. [doi:10.1063/1.3234380]
Resumo:
Fe is still the commonly used dopant to fabricate semi-insulating(SI) InP, a key material for high-speed electronic and optoelectronic devices. High resolved absorption spectra of the internal d-d shell transitions at Fe2+ in InP and the related phonon sidebands and a series of iron related absorption Lines are presented. Detailed infrared absorption study of the characteristic spectra of four zero-phonon lines(ZPLs), which are attributed to transitions within the 5D ground state of Fe2+ (3d(6)) on the indium site in a tetrahedral crystal field of phosphorus atoms and their temperature effects are given.
Resumo:
中国沙棘是一种雌雄异株、风媒传粉的灌木或乔木,在中国西南的卧龙自然保护区有广泛的分布。本研究以采集于四川卧龙自然保护区5 个海拔(1800 m、2200 m、2600 m、3000 m、3400 m)梯度的中国沙棘天然群体为材料,以ISSR 和AFLP 标记技术研究其遗传多样性水平及其遗传结构,旨在了解卧龙地区中国沙棘天然群体的遗传多样性水平以及遗传多样性在群体间、群体内以及雌雄亚群体间的分布和特征,为中国沙棘树种的遗传改良及种质资源保存提供遗传研究背景与实验依据。同时探讨ISSR、AFLP 和RAPD三种标记对中国沙棘天然群体的遗传变异水平和群体间遗传结构的评估能力和各自的优缺点。研究得出以下主要结论: 1. ISSR和AFLP分析都表明卧龙自然保护区的中国沙棘群体拥有较高的遗传变异水平(h = 0.249,HT = 0.305)。出现这种结果的主要原因可能与卧龙自然保护区多变的气候条件和生境的异质度大有关。 2. ISSR 和AFLP 都揭示出卧龙自然保护区中国沙棘群体的遗传多样性随着海拔的增加发生显著的变化,表现为中海拔群体(2200 m 和2600 m)比高海拔群体(3000 m 和3400 m)和低海拔群体(1800 m)有更高的遗传多样性的趋势。出现这种趋势的可能解释是低海拔群体处在相对高温和相对干旱的环境,高海拔群体受到低温和紫外线胁迫,而中海拔群体存在中国沙棘生长的适宜环境。 3. ISSR 和AFLP 分析都表明:卧龙自然保护区中国沙棘的遗传结构遵循分布范围广、交配系统以异交为主的木本植物的通常模式,即大多数的遗传变异存在于群体内,只有少部分的遗传变异存在于群体间。 4. 经Mantel 检测表明,卧龙自然保护区中国沙棘群体间的海拔距离和对应遗传距离之间存在显著的正相关关系,即随着垂直海拔距离的增加,群体间的遗传距离也随之增加。Mantel 检测结果以及聚类分析将卧龙自然保护区5 个不同海拔的中国沙棘群体分为低、中、高海拔群体三组的研究结果都表明,海拔很可能是限制群体间基因交流的主要因素。 5. ISSR 分析发现同一海拔的雌雄亚群体首先聚类的研究结果表明,同一海拔的雌雄亚群体在遗传上最相似。方差分析结果表明只有3.8%的总遗传变异存在于雌雄亚群体间,这可能与雌雄植株间的交配和遗传物质的混合有关。 6. ISSR、AFLP 和RAPD 分析都表明卧龙自然保护区不同海拔的中国沙棘天然群体的遗传多样性水平较高。它们的分析结果估算得到的Nei's 平均基因多样度(h)分别为0.249、0.214 和0.170。从该结果可以看出ISSR 和AFLP 比RAPD 检测到更多的遗传多态性,这很可能是不同标记检测的基因组的位点不同所致。 7. 依据对不同标记系统的比较分析,认为ISSR、AFLP 和RAPD 三种分子标记系统都能成功地用于调查卧龙自然保护区不同海拔的中国沙棘群体的遗传变异水平及遗传变异结构,提供关于中国沙棘天然群体多态性水平和遗传变异分布的有用信息。在三者中,AFLP 具有最高效能指数和标记指数,在确定种间分类关系或鉴别个体方面是一种比较理想的标记。 Hippophae rhamnoides subsp. sinensis, a dioecious and deciduous shrub species,occupies a wide range of habitats in the Wolong Nature Reserve, Southwest China. Ourpresent study investigated the pattern of genetic variation and differentiation among fivenatural populations of H. rhamnoides subsp. sinensis, occurring along an altitudinal gradientthat varied from 1,800 to 3,400 m above sea level in the Wolong Natural Reserve, by usingISSR and AFLP markers to guide its genetic improvement and germplasm conservation. And,comparative study of ISSR, AFLP and RAPD was performed to detect their capacity toestimating the level and pattern of genetic variation occurring among the five elevationpopulations of H. rhamnoides subsp. sinensis, and to discuss their application to the study onplant genetics. The results were list following: 1. The ISSR and AFLP analysis conducted for the H. rhamnoides subsp. sinensispopulations located in the Wolong Natural Reserve of China revealed the presence of highlevels of genetic variation (h = 0.249, HT = 0.305). Besides such features as relatively widedistribution, dominantly outcrossing mating system, and effective seed dispersal by small animals and birds, it is sometimes argued that hard climatic conditions and heterogeneous habitats may also contribute to high levels of diversity. 2. Genetic diversity of H. rhamnoides subsp. sinensis populations was found to varysignificantly with changing elevation, showing a trend that mid-elevation populations (2,200m and 2,600 m) were genetically more diverse than both low-elevation (1,800 m) andhigh-elevation populations (3,000 m and 3,400 m). H. rhamnoides subsp. sinensis is thoughtto be stressed by drought and high temperature at low elevations, and by low temperature athigh elevations. The high genetic variability present in the mid-elevation populations of H.rhamnoides subsp. sinensis is assumed to be related to a greater plant density in the middlealtitudinal zone, where favorable ecological conditions permit its continuous distributioncovering the zone from 2,200 m to 2,600 m above sea level. 3. The genetic structure of H. rhamnoides subsp. sinensis revealed by ISSRs andAFLPs followed the general pattern detected in woody species with widespread distributionsand outcrossing mating systems. Such plants possess more genetic diversity withinpopulations and less variation among populations than species with other combinations oftraits. 4. In the present study, Mantel tests showed positive correlations between altitudinaldistances and genetic distances among populations or subpopulations. The observedrelationship between altitude and genetic distances, and the result of the cluster analysisincluding populations or male subpopulations and classifying the groups into three altitudeclusters suggest that altitude is a major factor that restricts gene flow between populationsand subpopulations. 5. The analysis of molecular variance showed that only 3.8% of the variability residedbetween female and male subpopulations. Such a very restricted proportion of the totalmolecular variance between female and male subpopulations is due to common sexuality andmixing of genetic material between females and males. 6. The analysis based on ISSRs, AFLPs and RAPDs all revealed relatively high levelsof genetic variation among different altitudinal populations of H. rhamnoides subsp. sinensisin Wolong Natural Reserve of China. Their estimates of mean Nei’s gene diversity is equal to0.249, 0.214 and 0.170 respectively, suggesting the higher capacity of detecting geneticvariation of ISSR and AFLP than RAPD. It might be ascribed to their distinct sensitivity todifferent type of genetic variation. 7. Based on the coparative study on ISSR, AFLP and RAPD, we drew a conclusion thatthey all successfully reveal some useful information concerning the level and pattern ofgenetic vatiation occurring among different elevation populations of H. rhamnoides subsp.sinensis. AFLP is a ideal tool to taxonomic study and individual identification for theirhighest efficiency index and marker index among the three marker systems.