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1.
During 1977 to 1980 the course of flowering and pollen quality were investigated inSalix cinerea, S. fragilis, andS. pentandra, the dominant woody species in a wetland area called “Mokré louky” near T?eboň, South Bohemia, Czechoslovakia. Results were compared with basíc climatological data, and decisive factors of flowering were estimated. BothS. cinerea andS. pentandra produced morphologically well developed pollen with a high degree of viability. Comparison in twelve habitats showed that the pollen ofS. fragilis was very sensitive to climatic factors, and that the marsh habitat “Mokré Louky” was hostile to the generative reproduction of this species. Optimal conditions for pollen germination in vitro were defined for all the three willows.  相似文献   

2.
Background and Aims Thiophores, which are typically desert gypsophytes, accumulate high (2–6 % S dry weight) sulphur concentrations and may possess unique tolerance to environmental stress factors, e.g. sulphate/metal toxicity, drought and salinity. Little is known of the prevalence of the behaviour or the associated physiological aspects. The aim of this study was to (a) determine the prevalence of thiophore behaviour in a group of Australian xerophytes; (b) identify elemental uptake/storage characteristics of these thiophores; and (c) determine whether the behaviour is constitutive or environmental.Methods The elemental composition of soils and the foliage of 11 species (seven genera) at a site in the Tanami Desert (NT, Australia) was compared and 13 additional Acacia species from other locations were examined for elevated calcium and sulphur concentrations and calcium–sulphur mineralization, thought to be particular to thiophores.Key Results Acacia bivenosa DC. and 11 closely related species were identified as thiophores that can accumulate high levels of sulphur (up to 3·2 %) and calcium (up to 6.8 %), but no thiophores were identified in other genera occupying the same habitat. This behaviour was observed in several populations from diverse habitats, from samples collected over three decades. It was also observed that these thiophores featured gypsum (CaSO4·2H2O) crystal druses that completely filled cells and vascular systems in their dried phyllode tissues.Conclusions The thiophores studied exhibit a tight coupling between sulphur and calcium uptake and storage, and apparently store these elements as inorganic salts within the cells of their foliage. Thiophore behaviour is a constitutive trait shared by closely related Acacia but is not highly prevalent within, nor exclusive to, xerophytes. Several of the newly identified thiophores occupy coastal or riparian habitats, suggesting that the evolutionary and ecophysiological explanations for this trait do not lie solely in adaptation to arid conditions or gypsiferous soils.  相似文献   

3.
Calcium is an important nutrient that can be limiting in many forest ecosystems, where acid deposition and other natural and anthropogenic activities have resulted in significant soil calcium depletion. Calcium’s critical role in physiological and structural processes and its limited mobility and storage in many organisms, make it a potential driver of ecosystem structure and function, but little is known about how changes in soil calcium affect community composition, especially in terrestrial vertebrates. The aim of this study was to establish relationships between the abundances of forest songbird species and soil calcium and to elucidate linking mechanisms by establishing simultaneous relationships with trophic and habitat variables. We measured soil calcium and pH, calcium-rich invertebrate abundances, vegetation, and songbird abundances at 14 interior forest sites across central Pennsylvania representing a range of soil calcium levels. Bird community composition varied with soil calcium and pH, with 10 bird species having the highest abundances in forests with high calcium soils, and five species having the highest abundances with low calcium soils. Bird species associated with low-calcium soils were associated with high densities of mountain laurel (Kalmia latifolia), an acid-loving shrub, whereas bird species associated with high-calcium soils were associated with high densities of saplings and high basal area of acid-sensitive tree species. Homogenization of soil conditions through land-use patterns and soil calcium depletion pose the risk of reducing the beta diversity of bird species across forest areas because community composition varied with soil calcium.  相似文献   

4.
Pinus mugo Turra is a typical pine tree from mountain habitats. It is ideal as a bioindicator for air quality monitoring, but, to the best of our knowledge, has never been implemented to determine organic compound concentrations. This study presents the initial methodology for the use of pine needles to measure contamination levels and evaluate genotoxicity potentials caused by long-range transport of pollutants at sites in the Slovak mountains in comparison to an industrial urban area. Pinus mugo needles have many positive attributes, particularly the five-year lifetime of needles compared with other species of pine. The presence of epicuticular wax on the surface of needles allows accumulation of lipophilic organic compounds. Pine needles were analyzed for POP compounds (PCBs, OCPs, PBDEs), PAHs, PFCs and lead. A pollen grain abortion assay with Pinus mugo species was also tested as a method to identify contamination of high mountain habitats. The concentration of organic compounds increased proportionally with needle age. Concentrations along the mountain transect were heavily influenced by atmospheric transport and proximity to potential sources of contamination from industry and residential areas from north and south of the mountain. The slope exposure direction had a large impact on concentrations of PBDEs (mainly for BDE 209). High concentrations of PFCs were discovered near a ski resort, where the use of these substances is high due to fluorinated ski waxes and personal outdoor clothing. A positive correlation between pollen grain abortivity and elevation was observed, with the strongest effect on pollutants at the top of the mountains. The results showed the highest genotoxicity at the site near a pulp mill (Zilina), where the frequency of abortive pollen grains was 3.1 times higher than at the control site. Lead content increased gradually with needle age, and a correlation was found between Pb levels in needles and pollen abortivity. It can be concluded that Pinus mugo is a suitable bioindicator species for assessment of long-term trends of atmospheric contamination in high mountain habitats.  相似文献   

5.

Background and Aims

In habitat mosaics, plant populations face environmental heterogeneity over short geographical distances. Such steep environmental gradients can induce ecological divergence. Lowland rainforests of the Guiana Shield are characterized by sharp, short-distance environmental variations related to topography and soil characteristics (from waterlogged bottomlands on hydromorphic soils to well-drained terra firme on ferralitic soils). Continuous plant populations distributed along such gradients are an interesting system to study intrapopulation divergence at highly local scales. This study tested (1) whether conspecific populations growing in different habitats diverge at functional traits, and (2) whether they diverge in the same way as congeneric species having different habitat preferences.

Methods

Phenotypic differentiation was studied within continuous populations occupying different habitats for two congeneric, sympatric, and ecologically divergent tree species (Eperua falcata and E. grandiflora, Fabaceae). Over 3000 seeds collected from three habitats were germinated and grown in a common garden experiment, and 23 morphological, biomass, resource allocation and physiological traits were measured.

Key Results

In both species, seedling populations native of different habitats displayed phenotypic divergence for several traits (including seedling growth, biomass allocation, leaf chemistry, photosynthesis and carbon isotope composition). This may occur through heritable genetic variation or other maternally inherited effects. For a sub-set of traits, the intraspecific divergence associated with environmental variation coincided with interspecific divergence.

Conclusions

The results indicate that mother trees from different habitats transmit divergent trait values to their progeny, and suggest that local environmental variation selects for different trait optima even at a very local spatial scale. Traits for which differentiation within species follows the same pattern as differentiation between species indicate that the same ecological processes underlie intra- and interspecific variation.  相似文献   

6.
Although agricultural habitats can provide enormous amounts of food resources for pollinator species, links between agricultural and (semi-)natural habitats through dispersal and foraging movements have hardly been studied. In 67 study sites, we assessed the interactions between mass-flowering oilseed rape fields and semi-natural grasslands at different spatial scales, and their effects on the number of brood cells of a solitary cavity-nesting bee. The probability that the bee Osmia bicornis colonized trap nests in oilseed rape fields increased from 12 to 59 % when grassland was nearby, compared to fields isolated from grassland. In grasslands, the number of brood cells of O. bicornis in trap nests was 55 % higher when adjacent to oilseed rape compared to isolated grasslands. The percentage of oilseed rape pollen in the larval food was higher in oilseed rape fields and grasslands adjacent to oilseed rape than in isolated grasslands. In both oilseed rape fields and grasslands, the number of brood cells was positively correlated with the percentage of oilseed rape pollen in the larval food. We show that mass-flowering agricultural habitats—even when they are intensively managed—can strongly enhance the abundance of a solitary bee species nesting in nearby semi-natural habitats. Our results suggest that positive effects of agricultural habitats have been underestimated and might be very common (at least) for generalist species in landscapes consisting of a mixture of agricultural and semi-natural habitats. These effects might also have—so far overlooked—implications for interspecific competition and mutualistic interactions in semi-natural habitats.  相似文献   

7.
The diverse epidendroid orchid tribe Neottieae is characterized by multiple transitions between autotrophy and mycoheterotrophy, allogamous and autogamous mating systems, pollen released as tetrads or monads, and pollen exine tectate or semitectate. We use transmission and scanning electron microscopy on pollen of ten species of Neottieae to investigate whether the differences in pollen aggregation and exine micromorphology and ultrastructure reflect phylogenetic relationships, or whether this variation is subject to ecological constraints. Our results showed that differences in exine micromorphology are mostly concordant with phylogenetic relationships in Neottieae, i.e. an ascending tendency of pollen ornamentation from tectate (Cephalanthera) to semitectate (e.g. Neottia). In contrast, pollen aggregation, when plotted on the most recent phylogeny, shows repeated transitions between monads and tetrads that could be related to ecological constraints. Tetrads are present in species that are nectar rewarding, whereas monads are common in deceptive species. Cephalanthera is characterized by recalcitrant pollen, including the frequent occurrence of collapsed pollen. In this genus, the observed shifts from allogamous to autogamous or cleistogamous mating systems could help to reduce pollen damage caused by exposure to dry habitats.  相似文献   

8.
Red soils, which are widely distributed in tropical and subtropical regions of southern China, are characterized by low organic carbon, high content of iron oxides, and acidity and, hence, are likely to be ideal habitats for acidophilic actinomycetes. However, the diversity and biosynthetic potential of actinomycetes in such habitats are underexplored. Here, a total of 600 actinomycete strains were isolated from red soils collected in Jiangxi Province in southeast China. 16S rRNA gene sequence analysis revealed a high diversity of the isolates, which were distributed into 26 genera, 10 families, and 7 orders within the class Actinobacteria; these taxa contained at least 49 phylotypes that are likely to represent new species within 15 genera. The isolates showed good physiological potentials for biosynthesis and biocontrol. Chemical screening of 107 semirandomly selected isolates spanning 20 genera revealed the presence of at least 193 secondary metabolites from 52 isolates, of which 125 compounds from 39 isolates of 12 genera were putatively novel. Macrolides, polyethers, diketopiperazines, and siderophores accounted for most of the known compounds. The structures of six novel compounds were elucidated, two of which had a unique skeleton and represented characteristic secondary metabolites of a putative novel Streptomyces phylotype. These results demonstrate that red soils are rich reservoirs for diverse culturable actinomycetes, notably members of the families Streptomycetaceae, Pseudonocardiaceae, and Streptosporangiaceae, with the capacity to synthesize novel bioactive compounds.  相似文献   

9.
Changes of abiotic and biotic conditions along elevational gradients represent serious challenges to organisms which may promote the turnover of species, traits and biotic interaction partners. Here, we used molecular methods to study cuticular hydrocarbon (CHC) profiles, biotic interactions and phylogenetic relationships of halictid bees of the genus Lasioglossum along a 2,900 m elevational gradient at Mt. Kilimanjaro, Tanzania. We detected a strong species turnover of morphologically indistinguishable taxa with phylogenetically clustered cryptic species at high elevations, changes in CHC profiles, pollen resource diversity, and a turnover in the gut and body surface microbiome of bees. At high elevations, increased proportions of saturated compounds in CHC profiles indicate physiological adaptations to prevent desiccation. More specialized diets with higher proportions of low‐quality Asteraceae pollen imply constraints in the availability of food resources. Interactive effects of climatic conditions on gut and surface microbiomes, CHC profiles, and pollen diet suggest complex feedbacks among abiotic conditions, ecological interactions, physiological adaptations, and phylogenetic constraints as drivers of halictid bee communities at Mt. Kilimanjaro.  相似文献   

10.
The germination of the pollen from11 individuals of six wildRosa species was studied. The presence of calcium resulted in increased pollen germination, longer pollen tubes, and in a decrease of the requirement of sucrose concentration in cultivation media. Pollen germination in the medium with Ca reached the values of pollen viability estimated by tetrazolium test in all cases except with roses with balanced heterogamy, of the sectionCaninae. The stimulating effect of calcium was generally most pronounced in the pollen from roses of hybrid nature, such asR. jundzillii, R. canina, and especially in the case of the calciphilous speciesR. eglanteria.  相似文献   

11.
The quality of pollen of tea (Camellia sinensis L.), big leaf podocarp tree [Podocarpus macrophyllus (Thumb.)] and sweet corn (Zea mays L.) as alternative food sources was evaluated for seven native phytoseiid mite species, Amblyseius eharai Amitai and Swirski, Euseius sojaensis (Ehara), Neoseiulus californicus (McGregor), Neoseiulus womersleyi (Schicha), Phytoseius nipponicus Ehara, Chanteius contiguus (Chant) and Typhlodromus vulgaris Ehara. Tea pollen was of high nutritional value for all seven phytoseiid species: most larvae developed to adults and most females oviposited well. Development and oviposition differed greatly among phytoseiid species when reared on big leaf podocarp tree pollen: A. eharai, T. vulgaris and C. contiguus could utilize the pollen as food, but the other phytoseiid species could not. In addition, big leaf podocarp tree pollen could be utilized by A. eharai as food for longer than the other pollen. The quality of sweet corn pollen was inferior in general, although it could somehow favor the development and oviposition of six phytoseiid species except for E. sojaensis.  相似文献   

12.
薛苹苹  高玉葆  何兴东 《生态学报》2013,33(5):1475-1481
为探索同一物种在不同生态区域钙组分特征的差异,选择我国北方沙地重要建群种油蒿(Artemisia ordosica)为研究对象,采集了内蒙古杭锦旗、乌审旗、阿拉善左旗以及宁夏盐池县和陕西榆林市榆阳区不同沙地类型、不同生长阶段的油蒿样品,利用连续组分法测定分析了油蒿的钙组分特征.结果表明,在油蒿的不同器官中,叶水溶性钙和醋酸溶性钙均显著高于枝和根,叶与根盐酸溶性钙均显著高于枝.在不同生态区域,降水量较多的地区油蒿体内水溶性钙含量较多,降水量较少的地区油蒿体内盐酸溶性钙含量较高.分析得知,降水条件较好的地区较高的水溶性钙主要体现在油蒿的叶中,而降水条件较差的地区较高的盐酸溶性钙主要体现在油蒿的叶和根中.油蒿在不同生长阶段钙组分没有显著差异,但不同类型沙地上油蒿的钙组分却有显著差异.可见,不同生态区域的油蒿,生境条件越好体内水溶性钙含量越高,生境条件越差体内盐酸溶性钙含量越高.  相似文献   

13.
The spatial distribution of Elateridae larvae in the Lower Irtysh valley has been analyzed. The larvae analyzed belonged to 19 Elateridae species inhabiting soils of the floodplain and the river terrace. It has been pointed out that the larvae of Paraphotistus nigricornis, Agriotes lineatus, Limonius parallelus, and Aplotarsus incanus are most tolerant to the regular spring flooding. It has been found that the species compositions of floodplains and terrace meadows are significantly different. As a rule, species with a wide tropical spectrum inhabit floodplain soils, including bush and forest habitats. At the same time, the terrace was dominated by species characteristic of open habitats, including the steppe zone. It has been revealed that the values of species diversity vary significantly in the floodplain and terrace plots, but the higher species richness (Menhinick index) was registered in the floodplain.  相似文献   

14.
Understanding the factors that determine habitat quality is of vital importance in ensuring appropriate habitat management. Here we used the Niobe fritillary (Argynnis niobe) as a study system to analyse the larval habitat preferences in a small network of heavy-metal grasslands in western Germany. The data were compared with the results of a previous study in coastal dune grasslands of the German North Sea. Based on this knowledge, we give management recommendations for the conservation of this threatened species. The key factors for the survival of A. niobe in heavy-metal grasslands were (i) open vegetation with a warm microclimate and (ii) sufficient host plants for the larvae. This reflects similar results from the previous study in coastal grey dune grasslands. However, in the heavy-metal grasslands, physiological stress generally slows down succession and favours the fritillary’s host plant, the metallophyte Viola calaminaria. As a result, the cover of the host plant was nearly twice as high in heavy-metal grasslands compared to the dune grasslands. Heavy-metal grasslands are of great significance for the conservation of A. niobe and overall butterfly diversity. Usually, the speed of succession in heavy-metal grasslands is slow and, hence, sites with high heavy-metal concentrations are characterised by relatively stable plant composition and vegetation structure. However, on soils with low heavy-metal content a loss of habitats of A. niobe and associated species of conservation concern may occur without management. On those sites sheep grazing seems to be an appropriate way to keep the habitats open and rich in violets.  相似文献   

15.
We measured changes in the feeding rate and food absorption efficiency of two suspension feeding bivalves, cross-trasplanted between habitats with special emphasis on their capacity for differential absorption of biochemical components from their food supply. Mulinia edulis were moved from the intertidal zone to the subtidal zone, and Mytilus chilensis from the subtidal to the intertidal zone for a period of 7 days, and then compared with animal that had not been transplanted. Experimentally prepared diets similar to those available in the two different environments were offered to the bivalves, and their rates of feeding and differential uptake of biochemical components were determined and statistically compared. The two species did not achieve complete acclimation of their feeding behaviour during the transplant period since the highest ingestion rates for biochemical components occurred under dietary conditions that reflected their habitats of origin. Absorption efficiency showed greater acclimation than the other physiological parameters measured, indicating the capacity of these species to modulate their enzymatic-digestive activity depending on food composition. We conclude that both Mytilus and Mulinia have a certain degree of physiological plasticity in their feeding behaviour and assimilatory balance of biochemical components, being greater in Mytilus. When both species encounter ambient food conditions characteristic of their normal habitats, they show maximum values of food absorption, while under conditions where their typical diets are exchanged (Mytilus in intertidal and Mulinia in subtidal), the energy absorbed declines in each, but in ways very different between the two species. Thus, Mytilus exposed to high concentrations of low quality seston reduced the energy absorbed by 31.7% compared to its normal habitat, while Mulinia exposed to low concentrations of high-quality food reduced their energy absorption by 64%.  相似文献   

16.
Introductions of alien plant species are often likely to consist of a few individuals. Thus, invasion success may strongly depend on their reproductive biology. A high number of self-compatible plants species are known to be successful colonizers of new habitats, even able to establish populations from single propagules. However, many other invasive species require pollen vectors. Here, we investigated the mating system of Buddleja davidii, a fast growing shrub native to China that colonizes quickly in disturbed habitats such as quarries, river banks, along railways and roads, both in its native and invasive regions. It was intentionally introduced to Europe as an ornamental plant because of its fragrant and showy flowers. We additionally studied its vulnerability to biparental inbreeding depression by performing a controlled crossing experiment using pollen from the same population or from geographically close and distant populations, respectively. As a measure for pollination success, we used capsule weight, seed number per capsule and seed weight for each treatment.  相似文献   

17.
We studied testate amoebae (testates) in the soils of coniferous and deciduous forests and in the wetland and aquatic habitats of Mexico. In 141 samples we found 205 taxa identified to the species or intraspecies level and 68 testate amoebae, which could not be identified to the species level. The highest species diversity of testates was found in the soils of the tropical rainforest (126 species and intraspecific taxa, including spp.) and in tropical wetlands (144 species and intraspecific taxa, including spp.). The study documented testate amoebae with a limited geographical distribution (genera Centropyxis, Cornuapyxis, Ellipsopyxis, Hoogenraadia, Planhoogenraadia, Apolimia, Certesella, Apodera, and Alocodera). We found that testate amoebae in the soils of Mexico had a high level of polymorphism and individual variability. We discuss the value of soil testate amoebae for defining biogeographical regions of Mexico.  相似文献   

18.
祁连山高山植物根际土放线菌生物多样性   总被引:2,自引:0,他引:2  
从祁连山老虎沟不同海拔位点的15种植物根际土中培养得到78株特异表型放线菌,并结合菌体形态、生理代谢特征、抗菌活性及16S rDNA序列对其生理及系统发育多样性进行了研究。结果表明,分离菌株分属于链霉菌属(Streptomyces spp.)(73株)、诺卡氏菌属(Nocardia spp.)(4株),另有1株与GenBank中同源性最高的菌株Micromonospora saelicesensis相似性达92%,为1潜在新种。链霉菌属为主要类群,占分离菌株的93.6%,该属菌株在5个海拔位点的15种植物根际土中均有分布,但存在海拔位点、植物种类的差异性和特异性;诺卡氏菌属的菌株仅见于海拔2200 m的猪毛菜、海拔2800 m的钉柱萎陵菜和3800 m处的甘肃蚤缀根际土中;1潜在新种分离自海拔2200 m处的沙生针茅根际土。次级代谢物产生和拮抗性筛选研究结果表明:H2O2酶、脂酶2(Tween-40)、脲酶、蛋白酶、脂酶3(Tween-80)、淀粉酶、H2S、脂酶1(Tween-20)、可溶性色素及有机酸这10类次级代谢物产生菌分别占供试菌株的89.7%、82.1%、70.5%、62.8%、53.8%、52.6%、48.7%、44.9%、32.1%和17.9%,其中,淀粉酶、脂酶1、色素和有机酸仅由链霉菌产生;有29株放线菌对参试人类病原菌具有抑制作用,占供试菌株的37.2%,分布于5个海拔位点的12种植物根际土,其中,从药用植物甘肃黄芪和四裂红景天根际土中分离到的抗性菌株占拮抗性放线菌总数的60%。研究表明,高山地区植物根际土放线菌资源丰富,菌株生理功能多样,是新放线菌种和生物活性物质的重要资源库。  相似文献   

19.
Foraging behavior is a critical adaptation by insects to obtain appropriate nutrients from the environment for development and fitness. Bumble bees (Bombus spp.) form annual colonies which must rapidly increase their worker populations to support rearing reproductive individuals before the end of the season. Therefore, colony growth and reproduction should be dependent on the quality and quantity of pollen resources in the surrounding landscape. Our previous research found that B. impatiens foraging preferences to different plant species were shaped by pollen protein:lipid nutritional ratios (P:L), with foragers preferring pollen species with a ~5:1 P:L ratio. In this study, we placed B. impatiens colonies in three different habitats (forest, forest edge, and valley) to determine whether pollen nutritional quality collected by the colonies differed between areas that may differ in resource abundance and diversity. We found that habitat did not influence the collected pollen nutritional quality, with colonies in all three habitats collecting pollen averaging a 4:1 P:L ratio. Furthermore, there was no difference in the nutritional quality of the pollen collected by colonies that successfully reared reproductives and those that did not. We found however, that “nutritional intake,” calculated as the colony‐level intake rate of nutrient quantities (protein, lipid, and sugar), was strongly related to colony growth and reproductive output. Therefore, we conclude that B. impatiens colony performance is a function of the abundance of nutritionally appropriate floral resources in the surrounding landscape. Because we did not comprehensively evaluate the nutrition provided by the plant communities in each habitat, it remains to be determined how B. impatiens polylectic foraging strategies helps them select among the available pollen nutritional landscape in a variety of plant communities to obtain a balance of key macronutrients.  相似文献   

20.
《Journal of Asia》2021,24(3):819-823
On-farm native plantings support insect pollinator diversity, however, they must move between this habitat and crops grown elsewhere on the farm if they are to have any possibility of delivering pollination services that benefit growers. To determine whether pollinator movement occurs, sticky traps to capture verified crop pollinating insects (bees and non-bees species) were placed at distances of 0, 50, 100, 150 and 250 m from 5 year old native plantings into adjacent grass crops on three farms in New Zealand. These were activated twice for 48 h in Dec 2017 and Jan 2018. Captured pollinators were examined for pollen originating from the native plantings. A total of 993 individuals from 13 crop pollinating species were counted of which 506 were examined for pollen. Eight individuals representing three pollinator species were found with pollen sourced from the plantings. Of these, the native bee Lasioglossum sordidum (n = 4) was found to have travelled up to 250 m, while the native flies Melangyna novaezelandiae (n = 3) and Odontomyia sp. (n = 1) travelled up to 150 m. Despite finding few pollinators moving between these habitats, we recommend further studies to assess (1) whether the current study is truly indicative of limited pollinator movement across these habitats at broader temporal (e.g. seasonal and yearly), spatial and system scales (e.g. a broader range of agriculture systems and regions). Such knowledge can inform farmers on whether or not it is worthwhile establishing on-farm native plantings to support pollinators.  相似文献   

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