濒危植物南方红豆杉遗传多样性的RAPD分析

采用RAPD技术检测了山西南部南方红豆杉8个种群的遗传多样性。利用21个10聚寡核苷酸引物共检测出134个位点,其中多态性位点123个,占91.79%,8个种群的遗传多态位点百分率分别为67.16%(红豆峡)、67.91%(凤凰谷)、66.42%(小梯河)、66.42%(蟒河)、50.75%(历山西峡)、43.28%(云蒙山)、78.36%(长治宾馆)、50.75%(磨河)。南方红豆杉的遗传多样性分析结果显示：Shannon指数为2.180,其中31.7%的遗传多样性来自种群间,68.3%来自种群内;Nei指数为0.571,种群间的遗传分化系数(Gst)为0.181。8个种群间的遗传相似性分析结果显示：壶关红豆峡和陵川凤凰谷种群间的遗传距离最小(0.109 2),壶关红豆峡和陵川蟒河种群间遗传距离最大(0.55)。本研究结果揭示,南方红豆杉自然种群具有较高的遗传多样性,其遗传多样性不是导致该种群濒危的主要原因,导致南方红豆杉种群濒危的原因可能与南方红豆杉自然种群及群落所在生境的直接破坏及其本身生物学和生态学特性所导致的自然更新不良有着密切的联系。     

Outbreeding, seedling establishment, and maladaptation in natural and reintroduced populations of rare and common Silene douglasii (Caryophyllaceae)

Reintroductions are increasingly used to enhance declining populations, yet comparative data for critical germination and establishment phases are seldom available for both rare and common herbaceous perennials. After introducing a total of >1800 seeds, we compared experimentally manipulated and natural populations of widespread Silene douglasii var. douglasii relative to rare S. douglasii var. oraria, known in only three coastal headlands. Despite equivalent ex situ germination, oraria field plots produced significantly fewer juveniles than douglasii plots indicating that seedling survival limits plant establishment. We also evaluated transplant vs. seed reintroductions as restoration tools, the effect of inbreeding on fitness, and the potential importance of buried seed pools. Germination declined rapidly for seeds over 1-2 years old, and only 2.2% of newly collected seeds of oraria survived as seedlings. Transplant survival over 5 years was greatest for outbred progeny; furthermore, 75% of the new seedlings emerged near outbred progeny from the original reintroduction. Despite similar ovule numbers and pollinator visitation, transplants exhibited 49-179% maladaptation in the formerly grazed site, with significantly lower fruit and seed set than adults in more diverse natural populations. This study experimentally identifies several key factors affecting plant reintroductions, facilitating effective development of large-scale reintroduction strategies for native perennials.     

Variability within the 10-Year Pollen Rain of a Seasonal Neotropical Forest and Its Implications for Paleoenvironmental and Phenological Research

Tropical paleoecologists use a combination of mud-water interface and modern pollen rain samples (local samples of airborne pollen) to interpret compositional changes within fossil pollen records. Taxonomic similarities between the composition of modern assemblages and fossil samples are the basis of reconstructing paleoclimates and paleoenvironments. Surface sediment samples reflect a time-averaged accumulation of pollen spanning several years or more. Due to experimental constraints, modern pollen rain samples are generally collected over shorter timeframes (1–3 years) and are therefore less likely to capture the full range of natural variability in pollen rain composition and abundance. This potentially biases paleoenvironmental interpretations based on modern pollen rain transfer functions. To determine the degree to which short-term environmental change affects the composition of the aerial pollen flux of Neotropical forests, we sampled ten years of the seasonal pollen rain from Barro Colorado Island, Panama and compared it to climatic and environmental data over the same ten-year span. We establish that the pollen rain effectively captured the strong seasonality and stratification of pollen flow within the forest canopy and that individual taxa had variable sensitivity to seasonal and annual changes in environmental conditions, manifested as changes in pollen productivity. We conclude that modern pollen rain samples capture the reproductive response of moist tropical plants to short-term environmental change, but that consequently, pollen rain-based calibrations need to include longer sampling periods (≥7 years) to reflect the full range of natural variability in the pollen output of a forest and simulate the time-averaging present in sediment samples. Our results also demonstrate that over the long-term, pollen traps placed in the forest understory are representative samples of the pollen output of both canopy and understory vegetation. Aerial pollen traps, therefore, also represent an underutilized means of monitoring the pollen productivity and reproductive behavior of moist tropical forests.     

Interspecific Pollen Transfer: Magnitude,Prevalence and Consequences for Plant Fitness

Interspecific pollen transfer (IPT) is one of the mechanisms underlying potential competition among plants for pollinators, and it refers to movement of pollen between different plant species by pollinators that visit their flowers simultaneously. Two components of IPT, related to each other, are distinguished: (a) heterospecific pollen deposition (HPD) on conspecific stigmas, which may interfere with fertilization by conspecific pollen; and (b) conspecific pollen loss (CPL) on heterospecific flowers, which may reduce the amount of pollen transferred between conspecific flowers. Thus, IPT may lead to reciprocal losses for male and female functions of the plant, with potentially important ecological and evolutionary consequences. In this review, we explore the magnitude and prevalence of IPT, examining documented mechanisms and evaluating such potential ecological and evolutionary consequences. We compiled existing evidence of interspecific pollinator sharing and interspecific pollinator switching between flowers of different species in natural communities. We evaluated the relative importance of both HPD and CPL from studies comparing these variables in pure vs. mixed floral neighborhoods, analyzing evidence for the claim that IPT is an evolutionary force promoting character displacement in habitat affinity, flowering times, and floral morphology. We also examined the findings of hand-pollination experiments carried out to reveal different mechanisms by which heterospecific pollen can affect performance of native pollen. Finally, we review evidence for impacts of alien plant species on native species' reproduction, and briefly comment on risks of crop-to-wild gene flow imposed by the release of genetically modified (transgenic) crops through IPT.     

Reproduction in Seagrasses: Pollen Development in Thalassia hemprichii, Halophila stipulacea and Thalassodendron ciliatum

The general features of pollen morphogenesis in three marinemonocotyledons, Thalassia hemprichii, Halophila stipulacea andThalassodendron ciliatum, are described in this paper. Thalassia disperses spherical trinucleate pollen grains. Inthis genus simultaneous cytokinesis generally produces an isobilateraltetrad of microspores, but linear and T-shaped configurationsalso occur, together with configurations intermediate betweenisobilateral and T-shaped. Partitioning is followed by a phaseof cellular degeneration affecting one or two, never more, membersof the tetrad. Subsequent development of the surviving, functionalmicrospores does not differ essentially from the pattern ofmorphogenesis in terrestrial flowering plants. Halophila disperses strings of four reniform trinucleate pollengrains contained in a mucilaginous moniliform tube. These ariseby successive transverse partitioning of an elongate mothercell and the linear unit so formed is maintained throughoutpollen development. The tetrad tube substance originates inthe tapetal periplasmodium and deposition begins soon aftermeiosis. Thalassodendron disperses filiform trinucleate pollen grains.The characteristic form of the pollen in this genus is attainedduring post-meiotic growth and differentiation, as in othergenera belonging to the same family. This contrasts with thesituation in seagrasses belonging to the Zosteraceae where thefiliform shape is established before meiosis. Precocious divisionof the microspore nucleus in Thalassodendron launches the binucleatepollen phase soon after the spores separate from the tetrad.The division precedes the vacuolate period; again, this is afeature of the family. In Thalassia the tapetal periplasmodium is progressively transformedinto thecal slime. In Thalassodendron and Halophila the periplasmodialresidue forms a superficial coating on the pollen wall and tetradtube. These products could be implicated in attachment and recognitionof the pollen at the stigma surface. Thalassia hemprichii, Halophila stipulacea, Thalassodendron ciliatum, seagrasses, pollen development     

转基因白桦的花粉活力及外源基因的遗传表达分析

采用荧光素二乙酸酯（FDA）染色比较分析转基因白桦花粉的活力的结果表明,转基因白桦的花粉活力均低于非转基因白桦。应用多重PCR和Northern杂交技术分析表明,转基因白桦花粉中有外源基因整合和转录表达。检测转基因白桦花粉中gus报告基因的活性,显示gus报告基因在花粉表达。     

MROS1, a Male Stamen-Specific Gene in the Dioecious Campion Silene latifolia Is Expressed in Mature Pollen

The MROS1 gene, one of the genes that are expressed specificallyin male reproductive organs of a dioecious campion Silene latifolia,was predicted to encode only 36 amino acids but have an intron.In situ hybridization revealed that MROS1 mRNA was localizedin mature pollen grains. (Received January 30, 1997; Accepted February 24, 1997)     

地域环境对青藏高原特有植物藏川杨生物学特性的影响

通过对西藏中、南部16个藏川杨种源地环境特征、植株和枝叶形态特征、生长习性等生物学特性的观测比较,发现藏川杨为高大、长寿乔木,株龄逾千年、株高达45 m、冠幅22 m,分布海拔高度2000～4500 m、分布区域跨越湿润、半湿润、半干旱和干旱区,随着分布区环境变化,不同种源藏川杨的树皮、枝条、芽、叶等形态特征呈现规律性变化,空气湿度增加、树干颜色变深、枝条被毛加重、顶生冬芽变窄、叶片长/宽比增加;半湿润区和灌溉区植株的叶面积、枝条长度增加,湿润区、阴湿地或环境条件恶劣地区植株叶片和枝条生长不佳,枝条干湿比相对较小。结果表明:藏川杨具有很强的环境适应能力和可塑性,耐旱,喜光、抗强光辐射,耐贫瘠、喜中性或弱碱性土壤,具有很高的生态和经济价值。     

Mate-Searching Behaviour of Common and Rare Wasps and the Implications for Pollen Movement of the Sexually Deceptive Orchids They Pollinate

Pollinator behaviour directly affects patterns of pollen movement and outcrossing rates in plants. In orchids pollinated by sexual deception of insects, patterns of pollen movement are primarily determined by the mate-searching behaviour of the deceived males. Here, using a capture-mark-recapture study (CMR) and dietary analysis, we compare mate-searching behaviour in relation to local abundance of two pollinator species and explore the implications for pollen movement in sexually deceptive Drakaea (Orchidaceae). Drakaea are pollinated solely by the sexual deception of male thynnine wasps. The rare Drakaea elastica and widespread D. livida occur sympatrically and are pollinated by the rare but locally common Zaspilothynnus gilesi, and the widespread and abundant Z. nigripes, respectively. Local abundance was significantly different with Z. nigripes twice as abundant as Z. gilesi. For the 653 marked wasps, there was no significant difference in median movement distance between Z. gilesi and Z. nigripes. However, the maximum movement distance was twice as high for Z. gilesi (556 m) compared with Z. nigripes (267 m). This is up to three times greater than previously reported for thynnines in CMR studies. Recapture rates were six times higher in Z. gilesi (57%) compared to Z. nigripes (9%). Pollen loads and wasp longevity were similar, suggesting that this difference in recapture rate arises due to differences in the number of males moving at a scale >500 m rather than through diet or mortality. Differences in the frequency of longer movements may arise due to variation in the spatial distribution of the wingless females. We predict that pollen movement will largely be restricted to within populations of Drakaea (<500 m), with few movements between populations (>500 m).     

Sexual Reproduction and Early Plant Growth of the Wollemi Pine (Wollemia nobilis), a Rare and Threatened Australian Conifer

The two known populations of the recently discovered rare andthreatened Wollemi Pine (Wollemia nobilis Jones, Hill and Allen)consist of a small number of large multi-stemmed adult treesand small seedlings. Female and male cones are produced on adulttrees with pollen release occurring in spring (October–November).Seed cones mature 16–19 months later in late summer andautumn and appear to be produced annually. Approximately 10%of seed produced in two consecutive years was viable, 25% ofwhich was damaged by animals. Glasshouse studies showed thatseed germination at 25 °C (day)/16 °C (night) proceededslowly but steadily at approx. 4% per week until, after 6 months,88% of apparently viable seed had germinated with the remainderof the seed rotting. Growth of potted seedlings in this temperatureregime was continuous (after a lag period of 4–6 months)with the monopodial axis growing 0.05–0.25 m in the firstyear, 0.5–0.6 m in the second year and 0.25–0.35m in the third year, attaining a total height of 0.8–1.2m. Multiple orthotropic shoots developed on some plants at thisstage, some of which outgrew the primary shoot in height. Thediameter of the stem below the cotyledon (just above the soil)grew 3–7 mm in the first year, 10–14 mm in the secondand 15–20 mm in the third at which time it was 25–34mm. The average number of lateral branches produced was five–17in the first year, 25–36 in the second year and 24–30in the third year giving a total of 60–77. The establishmentof Wollemi Pine in the wild does not appear limited by the inherentviability of seed and potential for early growth of seedlings.Copyright 1999 Annals of Botany Company Wollemia nobilis, Wollemi Pine, Araucariaceae, conifer, rare and threatened plant, cone, seed, germination, seedling growth.     

珍稀濒危植物海南粗榧种群遗传多样性研究

利用RAPD技术对珍稀濒危植物海南粗榧（Cephalotaxus manniiHook.f.)遗传多样性水平,分布、濒危原因及物种保护等问题进行了探讨。结果表明：1、海南粗榧在海南岛的5个取样地点表现出低水平的遗传多样性,对环境变化物适应能力不强;2、海南粗榧种群内和种群间的遗传多样性所占比例有很大差异,绝大部分变异分布于种群内（DAN多样性为85.1%);种群间仅有较低程度的分化;3、人为砍伐,植被破坏,台风、被食用遗传漂变是海南粗榧遗传多样性低水平的主要原因,也是物种濒危的主要原因;4、对于呈零星分布的濒危植物海南粗榧的研究与保护,应充分考虑个体小环境之间的差异。考虑影响小种群的随机因素;5、应采取有力措施,就地保护现有种群,并寻求适当的方法迅速扩展种群,降低基因丧失率;选择遗传多样性较高且破坏相对较小的黎母岭种群作为保护重点;同时应加强对其他种群的保护与管理;6、海南粗榧种群内,种群音质遗传多样性在不同引物之间有较大差别。多态性位点百分率则是种群间的变化大于引物间的变化。     

Within-Otolith Variability in Chemical Fingerprints: Implications for Sampling Designs and Possible Environmental Interpretation

Largely used as a natural biological tag in studies of dispersal/connectivity of fish, otolith elemental fingerprinting is usually analyzed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). LA-ICP-MS produces an elemental fingerprint at a discrete time-point in the life of a fish and can generate data on within-otolith variability of that fingerprint. The presence of within-otolith variability has been previously acknowledged but not incorporated into experimental designs on the presumed, but untested, grounds of both its negligibility compared to among-otolith variability and of spatial autocorrelation among multiple ablations within an otolith. Here, using a hierarchical sampling design of spatial variation at multiple scales in otolith chemical fingerprints for two Mediterranean coastal fishes, we explore: 1) whether multiple ablations within an otolith can be used as independent replicates for significance tests among otoliths, and 2) the implications of incorporating within-otolith variability when assessing spatial variability in otolith chemistry at a hierarchy of spatial scales (different fish, from different sites, at different locations on the Apulian Adriatic coast). We find that multiple ablations along the same daily rings do not necessarily exhibit spatial dependency within the otolith and can be used to estimate residual variability in a hierarchical sampling design. Inclusion of within-otolith measurements reveals that individuals at the same site can show significant variability in elemental uptake. Within-otolith variability examined across the spatial hierarchy identifies differences between the two fish species investigated, and this finding leads to discussion of the potential for within-otolith variability to be used as a marker for fish exposure to stressful conditions. We also demonstrate that a ‘cost’-optimal allocation of sampling effort should typically include some level of within-otolith replication in the experimental design. Our findings provide novel evidence to aid the design of future sampling programs and improve our general understanding of the mechanisms regulating elemental fingerprints.     

Multi Year Observations Reveal Variability in Residence of a Tropical Demersal Fish,Lethrinus nebulosus: Implications for Spatial Management

Off the Ningaloo coast of North West Western Australia, Spangled Emperor Lethrinus nebulosus are among the most highly targeted recreational fish species. The Ningaloo Reef Marine Park comprises an area of 4,566 km² of which 34% is protected from fishing by 18 no-take sanctuary zones ranging in size from 0.08–44.8 km². To better understand Spangled Emperor movements and the adequacy of sanctuary zones within the Ningaloo Reef Marine Park for this species, 84 Spangled Emperor of a broad spectrum of maturity and sex were tagged using internal acoustic tags in a range of lagoon and reef slope habitats both inside and adjacent to the Mangrove Bay Sanctuary zone. Kernel Utilisation Distribution (KUD) was calculated for 39 resident individuals that were detected for more than 30 days. There was no relationship with fish size and movement or site fidelity. Average home range (95% KUD) for residents was 8.5±0.5 km² compared to average sanctuary zone size of 30 km². Calculated home range was stable over time resulting in resident animals tagged inside the sanctuary zone spending ∼80% of time within the sanctuary boundaries. The number of fish remaining within the array of receivers declined steadily over time and after one year more than 60% of tagged fish had moved outside the sanctuary zone and also beyond the 28 km² array of receivers. Long term monitoring identified the importance of shifting home range and was essential for understanding overall residency within protected areas and also for identifying spawning related movements. This study indicates that despite exhibiting stable and small home ranges over periods of one to two years, more than half the population of spangled emperor move at scales greater than average sanctuary size within the Ningaloo Reef Marine Park.     

Variability in Growth Characteristics of Different E. coli O157:H7 Isolates, and its Implications for Predictive Microbiology

In growth experiments 75 clinical isolates of Escherichia coli O157:H7 were studied for the variability in seven growth characteristics: minimum, optimum and maximum growth temperature, minimum and optimum pH, minimum water activity and optimum specific growth rate. With these characteristics, growth can be predicted for any given set of conditions (temperature, acidity and water activity), when the gamma model is used as predictive microbiology model. The optimum specific growth rate of the 75 strains, as conceptually defined by the model, had a mean value of 4.71 (ln[emsp4 ](count)/h), with a standard deviation of 0.39. It could not be shown that the mean optimum specific growth rate differs significantly per strain, so the variability found will predominantly be the result of other sources of variation. In contrast, the experimental results suggest that the differences in minimum temperature of growth may be partially strain specific. As variability in growth is crucial for quantitative risk assessment, the results were implemented in the gamma model. Predictions at three sets of growth conditions were compared with predictions of the Pathogen Modeling Program (PMP) (USDA) and some published experimental results. This comparison showed that growth rates higher than those published and outside the 95% confidence interval predicted by the PMP are feasible. Although it needs further development and additional tests, our approach offers a promising strategy to predict the variability in growth.     

Pollen Development in Actinidia deliciosa var. deliciosa: Histochemistry of the Microspore Mother Cell Walls

The development of the microspore mother cell walls in Actinidiadeliciosa (kiwifruit) has been studied using light and electronmicroscopy. The microspore mother cell wall is similar, histochemically,and structurally in anthers from both functionally staminateand functionally pistillate flowers. Deposition, which beginsduring early prophase I, produces an electron-dense multilaminatedwall layer (layer a) and by the end of meiosis I a thick electron-lucentlayer (layer b) to the inside of this multilayered wall. Thereasons for histochemical differences and similarities betweenthese layers are discussed. The original primary wall persistsuntil the late uninucleate microspore stage. Layer (b), whichis probably mainly callose, dissolves at the late tetrad/earlymicrospore stage while layer (a), which probably also containsother polysaccharides, persists and dissolves concurrently withthe primary wall. Actinidia deliciosa, kiwifruit, microspore mother cell wall, callose, histochemistry, light microscopy, electron microscopy, male sterility