石耳科(子囊菌门)的新种和新分布

本文报导了石耳科的八个种,其中新种四个,即阿尔泰石耳,鳞芽石耳、亚石耳及太白石耳;三个种是中国的新分布,即皱石耳、亚光石耳及淡腹疤脐衣;一个种即白根石耳为中国及蒙古的新分布。     

石耳科(子囊菌亚门)的间断分布和替代现象

本文报道了石耳科的两个亚洲的,也是美洲以外的新记录种,即角石耳与深色石耳。进一步证实了单果石耳在南大西洋的,即南美洲和南部非洲的间断分布。对于上述种类以及本科其它一些种类的间断分布和替代现象进行了分析讨论。     

Antimicrobial activity of extracts of the lichens <Emphasis Type="Italic">Cladonia furcata,Parmelia caperata,Parmelia pertusa,Hypogymnia physodes</Emphasis> and <Emphasis Type="Italic">Umbilicaria polyphylla</Emphasis>

Antimicrobial features of acetone, methanol and aqueous extracts of lichens of Cladonia furcata, Parmelia caperata, Parmelia pertusa, Hypogymnia physodes and Umbilicaria polyphylla were investigated by two different methods at the same time. Testing of antimicrobial activities of extracts from five species of lichens was performed by disc diffusion test in relation to Gram-positive and Gram-negative bacteria and fungal organisms, and through determination of minimal inhibitory concentration (MIC) by Broth Tube Dilution method. The obtained results indicated that acetone and methanol extracts of all investigated lichens in different concentrations manifested selective antibacterial and antifungal activity. That activity was more evident in relation to Gram-positive, than Gram-negative bacteria and fungal organisms. Acetone and methanol extracts of lichens Parmelia pertusa, Hypogymnia physodes and Umbilicaria polyphylla inhibited the growth of all tested microorganisms, most of all of lichens Cladonia furcata and Parmelia caperata. Although, the methanol extracts were generally the most active against the test organisms, the lowest MIC value was measured for acetone extract of species Cladonia furcata 0.39 mg/mL in relation to bacterium Bacillus subtilis. Aqueous extracts of investigated lichens were inactive against all tested organisms.     

Evaluation of antimicrobial activity of the lichens <Emphasis Type="Italic">Lasallia pustulata,Parmelia sulcata,Umbilicaria crustulosa</Emphasis>, and <Emphasis Type="Italic">Umbilicaria cylindrica</Emphasis>

The antimicrobial properties of acetone, methanol, and aqueous extracts of the lichens Lasallia pustulata, Parmelia sulcata, Umbilicaria crustulosa, and Umbilicaria cylindrica were studied comparatively in vitro. Antimicrobial activities of the extracts of different lichens were estimated by the disk diffusion test for Gram-positive bacteria, Gram-negative bacteria, and fungal organisms, as well as by determining the MIC (minimal inhibitory concentration). The obtained results showed that the acetone and methanol extracts of Lasallia pustulata, Parmelia sulcata, and Umbilicaria crustulosa manifest antibacterial activity against the majority of species of bacteria tested, in addition to selective antifungal activity. The MIC of lichen extracts was lowest (0.78 mg/ml) for the acetone extract of Lasallia pustulata against Bacillus mycoides. Aqueous extracts of all of the tested lichens were inactive. Extracts of the lichen Umbilicaria cylindrica manifested the weakest activity, inhibiting only three of the tested organisms.     

Lecanoric acid,a secondary lichen substance with antioxidant properties from <Emphasis Type="Italic">Umbilicaria antarctica</Emphasis> in maritime Antarctica (King George Island)

Eight lichen species, Cetraria aculeata, Cladonia furcata, Pseudephebe pubescens, Sphaerophorus globosus, Stereocaulon alpinum, Umbilicaria antarctica, Usnea antarctica and Usnea aurantiacoatra, were collected from King George Island, maritime Antarctica, for the evaluation of antioxidant activities. Anti-linoleic acid peroxidation activity, free radical scavenging activity, reducing power and superoxide anion scavenging activity were assessed of methanol and acetone extract of the lichens in vitro. Extract of Umbilicaria antarctica, Cladonia furcata, Sphaerophorus globosus and Usnea antarctica were found to have strong in vitro antioxidant properties. In general, acetone extract exhibited stronger activities than methanol extract. The activity-guided bioautographic TLC and HPLC analysis demonstrated that lecanoric acid was the main antioxidant compound in the acetone extract of Umbilicaria antarctica, the most potent antioxidant lichen species among the test species. The results suggested that several Antarctic lichens and their substances can be used as novel bioresources of natural antioxidants.     

Photobiont selectivity for lichens and evidence for a possible glacial refugium in the Ross Sea Region, Antarctica

Lichens are a symbiosis consisting of heterotrophic, fungal (mycobiont) and photosynthetic algal or cyanobacterial (photobiont) components. We examined photobiont sequences from lichens in the Ross Sea Region of Antarctica using the internal transcribed spacer region of ribosomal DNA and tested the hypothesis that lichens from this extreme environment would demonstrate low selectivity in their choice of photobionts. Sequence data from three targeted lichen species (Buellia frigida, Umbilicaria aprina and Umbilicaria decussata) showed that all three were associated with a common algal haplotype (an unnamed Trebouxia species) which was present in all taxa and at all sites, suggesting lower selectivity. However, there was also association with unique, local photobionts as well as evidence for species-specific selection. For example, the cosmopolitan U. decussata was associated with two photobiont species, Trebouxia jamesii and an unnamed species. The most commonly collected lichen (B. frigida) had its highest photobiont haplotype diversity in the Dry Valley region, which may have served as a refugium during glacial periods. We conclude that even in these extreme environments, photobiont selectivity still has an influence on the successful colonisation of lichens. However, the level of selectivity is variable among species and may be related to the ability of some (e.g. B. frigida) to colonise a wider range of habitats.     

Epiphytic lichen is associated with species richness of gall-inducing aphids but not with niche differentiation among them

The presence of epiphytic foliose lichen amplifies the heterogeneity of habitat by creating shelters for insects living on tree bark. It thus should enhance species number and spatial niche segregation among these canopy insects. We studied this hypothesis in a field experiment using four aphid species that induce galls on Pistacia atlantica trees covered with Xanthoria parietina lichen. In autumn 2008, 3 months after aphid fundatrices were oviposited, we marked six branches on each of 29 trees. Two served as a control, whereas the other four were isolated with insect glue; two of them were scraped with sandpaper to remove epiphytic foliose lichens. We therefore obtained three treatments comprising control branches, isolated branches with lichen, and isolated branches without lichen. In summer 2009, we counted all the galls developing on five new annual shoots on each of 174 branches. We observed more cecidogenic aphid species on all the branches with lichens than without, but each species at different proportions. The different frequencies of utilization of the lichen did not lead to habitat partitioning between species. In conclusion, although habitat heterogeneity itself was associated with species richness and population abundance, it did not induce spatial niche segregation. Considering that many economically important insect species, pests and natural enemies, oviposit or spend some portion of their lives in bark cracks, it is possible that some can use lichens too for protection or/and oviposition sites. As a consequence, lichens may affect management of agrosystems and their impacts should be investigated more deeply in such contexts.     

Competitive behaviour of umbilicate lichens – an experimental approach

The lichens Lasallia pustulata and Umbilicaria spodochroa grow in dense monospecific or mixed populations on the coastal cliffs of southern Scandinavia. Attached to the substrate by only a thin central holdfast, their shield-shaped thalli compete for light and space for growth by overlapping each other. Matched pair experiments in the laboratory and field observations of interacting pairs show that different behavioural responses to precipitation tend to result in the margins of U. spodochroa overlapping those of L. pustulata within a few minutes. The behaviour is apparently caused by different capacities for water absorption in the upper and lower cortices of the species. An initial period of repeated encounter caused by thallus expansion and contraction during precipitation will be followed by a period in which U. spodochroa grows to overlap L. pustulata more and more. When the overlapping lichens are wet, flexible and photosynthetically active, the thallus above rests directly on the upper surface of the one below. Very little light is transmitted through thalli of U. spodochroa, and the shaded parts of L. pustulata are retarded in their growth and die off. Received: 29 August 1996 / Accepted: 19 April 1997     

Halogenated anthraquinones from the rare southern Illinois lichen Lasallia papulosa

Abstract:Four anthraquinones were isolated from the foliose lichen, Lasallia papulosa (Ach.) Llano. Two of the anthraquinones are known compounds, previously isolated from Lasallia papulosa, while the other two were reported previously as secondary metabolites from laboratory-cultured Nephroma laevigatum, and are isolated here for the first time from lichens in their natural habitat. All compounds were characterized by UV spectrophotometry, mass spectrometry, ¹H NMR and ¹³C NMR. The products were identified as 7-chloroemodin, valsarin (7-chloro-5-hydroxyemodin), 5-chloro-1- O -methylemodin and 5-chloro-1- O -methyl-ω-hydroxyemodin.     

Population-level resource selection by sympatric brown and American black bears in Alaska

Distribution theory predicts that for two species living in sympatry, the subordinate species would be constrained from using the most suitable resources (e.g., habitat), resulting in its use of less suitable habitat and spatial segregation between species. We used negative binomial generalized linear mixed models with fixed effects to estimate seasonal population-level resource selection at two spatial resolutions for female brown bears (Ursus arctos) and female American black bears (U. americanus) in southcentral Alaska during May–September 2000. Black bears selected areas occupied by brown bears during spring which may be related to spatially restricted (i.e., restricted to low elevations) but dispersed or patchy availability of food. In contrast, black bears avoided areas occupied by brown bears during summer. Brown bears selected areas near salmon streams during summer, presumably to access spawning salmon. Use of areas with high berry production by black bears during summer appeared in response to avoidance of areas containing brown bears. Berries likely provided black bears a less nutritious, but adequate food source. We suggest that during summer, black bears were displaced by brown bears, which supports distribution theory in that black bears appeared to be partially constrained from areas containing salmon, resulting in their use of areas containing less nutritious forage. Spatial segregation of brown and American black bears apparently occurs when high-quality resources are spatially restricted and alternate resources are available to the subordinate species. This and previous work suggest that individual interactions between species can result in seasonal population-level responses.     

Metabolic recovery of continental antarctic cryptogams after winter

The activation of metabolism after the winter period was investigated in several mosses and lichens in continental Antarctica. Thalli that were still in their over-wintering inactive state in early spring were sprayed artificially and the time-dependent activation of photosystem II (PSII), carbon fixation and respiration was determined using gas exchange and chlorophyll a fluorescence techniques. The investigated lichens recovered PSII activity almost completely within the first few minutes and gross photosynthesis was fully reactivated within a few hours. In contrast, photosynthesis took much longer to recover in mosses, which could indicate a general difference between the green-algal symbionts in lichens and moss chloroplasts. Only small and quickly reversible increased rates of respiration were observed for the foliose lichen Umbilicaria aprina from a more xeric habitat. In contrast, species occurring near persistent meltwater, such as the moss Bryum subrotundifolium and the lichen Physcia caesia, had highly increased respiration rates that were maintained for several days after activation. Calculation of the carbon balances indicated that the activation pattern strongly dictated the length of time before a carbon gain was achieved. It appears that the differences in recovery reflect the water relations of the main growth period in summer.     

Mechanisms of species coexistence: a field test of theoretical models using intertidal snails

Competitor coexistence is often facilitated by spatial segregation. Traditionally, spatial segregation is predicted to occur when species differ in the habitat in which they are either superior at competing for resources or less susceptible to predation. However, predictions from a behavioural model demonstrate that spatial segregation and coexistence can also occur in the absence of such interspecific trade‐offs in competitive ability and vulnerability to predation. Unlike other models of competitor coexistence this model predicts that when species rank both habitat productivity and ‘riskinesses’ similarly, but differ slightly in their habitat‐specific vulnerabilities to predators, they will tend to segregate across habitats, with the species experiencing the higher ratio of mortality risk across the habitats occurring primarily in the safer habitat. Here, we investigate the hypothesis that intraspecific trade‐offs between resource availability and mortality risk can lead to spatial segregation of competing species by (1) documenting the spatial (i.e. intertidal) distribution of two marine snails, Littorina sitkana and L. subrotundata and (2) performing field experiments to quantify growth and mortality rates of each species at ‘low’ and ‘high’ intertidal heights. Our results indicate that both species agree on the rankings of habitat riskiness and productivity, experiencing higher predation and higher growth in low‐ than in high‐intertidal habitats. However, L. sitkana and L. subrotundata experienced differences in their habitat‐specific mortality risks and growth rates. Despite both species being similarly at risk of predation in high‐intertidal habitats (where mortality was lower), L. subrotundata was subject to significantly higher mortality than L. sitkana at the low‐intertidal height. In contrast, growth rate differences between habitats were greater for L. sitkana than for L. subrotundata. Whereas both species grew at the same rate at the high‐intertidal level (where growth was lower), L. sitkana individuals grew more rapidly than L. subrotundata snails at the low‐intertidal level. As predicted by the behavioural model, the species that experienced the higher ratio of mortality across habitats (i.e. L. subrotundata) occurred exclusively in the safer, high‐intertidal habitat. Taken together, these results provide support for the hypothesis that spatial segregation, and potentially competitor coexistence, can occur in the absence of interspecific trade‐offs in resource acquisition ability or vulnerability to predation.     

Vegetation and ecology of ice-free areas of Northern Victoria Land,Antarctica

Summary At Birthday Ridge, a small ice free area in northern Victoria Land (70°48S, 167°00E), cryptogamic vegetation is mostly confined to gaps between granitc rocks. The sheltering effect on lichens and mosses was analyzed by continuous measurements of the microclimate at various levels between the rocks. Although warming by solar radiation was favourable for the existence of cryptogams, rocks strongly insolated were mostly devoid of lichens and mosses. Lichens in the soaked active state were heated to above air temperature but did not reach more than 10°C. The presence of lichens was dependent on the moisture conditions of the habitat. It was observed that snow, the only source of moisture, accumulated in summer only in deeper levels between rocks, and that the snow rapidly melted on contact with the lichens. After a snow shower,Usnea sulphurea gained 67% andUmbilicaria decussata 94% of their maximum water capacity. During one quarter of the time period of 7 days the lichens were soaked and therefore capable of carrying out photosynthesis. The lichens in soaked state had always less than optimum temperatures for net photosynthesis. The rock gaps at Birthday Ridge form oases, the only localities where moisture is provided, and temperature is high enough to enable growth of lichens and mosses.Bryum is also able to exist in the upper 3 cm of soil.     

山西稀有濒危植物脱皮榆群落的种间分离

通过对山西太岳山脱皮榆群落1 hm²样地内出现的14种乔木进行调查,在应用ArcGIS软件分析每个个体的最近邻体植株的基础上,采用N×N最近邻体列联表及其2×2列联表截表的方法和Pielou分离指数计算分析了脱皮榆群落的种间分离规律,并根据种间分离情况以及物种对环境的适应方式,利用PCA排序将样地中14个物种进行了生态种组的划分。结果表明:（1）该群落中出现的14种乔木构成的91个种对中,随机毗邻种对占绝大多数（74.73%）,正分离种对较少（23.07%）,负分离种对极少（2.20%）,群落趋于稳定。（2）群落的种间分离在不同种之间存在着一定的差异,脱皮榆仅与其他树种随机毗邻;正分离常发生在群落中的优势种之间,而负分离常发生在群落中的伴生种之间。（3）种间分离与群落的生境异质性和物种的生态需求具有密切的关系,即两个具有不同生境要求的物种之间常常发生正分离,而具有相同或相似生境要求的物种之间常常发生负分离。（4）脱皮榆群落中14种乔木可划分为3个生态种组。研究认为,脱皮榆群落内物种的总体分离规律为全面不分离。由生境异质性、物种间不同的生物学特性和生态需求为基础的种间关系可能是维持太岳山脱皮榆群落稳定共存的机制之一。     

Trophic interactions and habitat segregation between competing Daphnia species

Summary Two commonly coexisting species of Daphnia segregate by habitat in many stratified lakes. Daphnia pulicaria is mostly found in the hypolimnion whereas D. galeata mendotae undergoes diel vertical migration between the hypolimnion and the epilimnion. I examined how habitat segregation between these two potentially competing species might be affected by trophic interactions with their resources and predators by performing a field experiment in deep enclosures in which I manipulated fish predation, nutrient levels, and the density of epilimnetic Daphnia. The results of the experiment indicate that habitat use by D. pulicaria can be jointly regulated by competition for food from epilimnetic Daphnia and predation by fishes. Patterns of habitat segregation between the two Daphnia species were determined by predation by fish but not by nutrient levels: The removal of epilimnetic fish predators resulted in higher zooplankton and lower epilimnetic phytoplankton densities and allowed D. pulicaria to expand its habitat distribution into the epilimnion. In contrast, increased resource productivity resulted in higher densities of both Daphnia species but did not affect phytoplankton levels or habitat use by Daphnia. The two species exhibit a trade-off in their ability to exploit resources and their susceptibility to predation by fish. D. g. mendotae (the less susceptible species) may thus restrict D. pulicaria (the better resource exploiter) from the epilimnion when fish are common due to lower minimum resource requirements than those needed by D. pulicaria to offset the higher mortality rate imposed by selective epilimnetic fish predators. D. g. mendotae does not appear to have this effect in the absence of fish.     

Seasonal Trends in Nitrogen Status of Antarctic Lichens

The thallus nitrogen (N) concentration of two dominant macrolichensof continental Antarctica (Usnea sphacelata and Umbilicariadecussata) was estimated each month for 1 year on a low roundedknoll on Clark Peninsula, Windmill Islands, Wilkes Land, Antarctica.Thallus N was significantly higher in Umbilicaria decussatathan in Usnea sphacelata and varied according to site. Duringthe winter months, when the lichens were metabolically inactive,thalli gradually accumulated N. At the onset of warmer conditions,thallus N content fell dramatically in both species, with thetiming of the decline being related to microclimatic conditions.The strongly seasonal pattern of metabolic activity in thesespecies is reflected in their nitrogen relations. Copyright2000 Annals of Botany Company Lichen, nitrogen, Antarctica, season, Usnea sphacelata, Umbilicaria decussata     

Interactions among species with contrasting dispersal modes explain distributions for epiphytic lichens

Understanding how the biodiversity response to climate change will be modified at ecological scales, e.g. by species interactions, is a major challenge. Lichen epiphytes – the close interdependent relationship between a heterotrophic fungus and photosynthetic partner (photobiont) – are used here to explore how interaction regimes (between lichen species, and between lichens and their photobionts) explain distribution patterns along spatial climatic gradients. To do this we tested field evidence for the ‘core‐fringe hypothesis’, which proposes a facilitative interaction; sexually‐reproducing and spore‐dispersed lichens with a requirement for resynthesis with a compatible photobiont (Nostoc) are facilitated by the prior establishment of asexual lichens which disperse both the fungus and photobiont together. We used two closely related Nephroma species which differ in their reproductive mode – N. laevigatum (sexual spore‐dispersed) and N. parile (asexual) – and compared their occurrence along a bioclimatic gradient to local habitat factors, including the co‐occurrence of asexual lichens which have shared specificity for compatible Nostoc genotypes. The results showed that: 1) N. laevigatum is significantly more likely to occur on trees that have already been colonised by asexual lichens with shared specificity for Nostoc, supporting the core‐fringe hypothesis, while 2) N. parile is independent of this association (strengthening the core‐fringe hypothesis), with its response to a precipitation gradient modified by microhabitat factors. This positive test for the core‐fringe hypothesis demonstrates how interaction regimes can fundamentally alter expectations under climate change. There is an assumption that spore‐dispersed lichen species could more easily track their suitable bioclimatic space through fragmented habitat, compared to asexual species with larger and heavier propagules. However, the establishment of spore‐dispersed lichen epiphytes into new habitat may be limited by the dispersal rates of asexual species, which act as key facilitators.     

Lack of habitat segregation and no interspecific territoriality in three syntopic cryptic species of the golden‐spectacled warblers Phylloscopus (Seicercus) burkii complex

It is widely accepted that exploitative competition prevents the coexistence of any two or more closely‐related species unless differences exists in their ecological niches and resource use. In sibling bird species, exploitative competition is reduced mainly by spatial segregation of competing species. Spatial segregation can be achieved in two basic ways: by using different habitats or microhabitats that each species is predominately exploiting, or by interspecific territoriality. To our knowledge, either habitat segregation or interspecific territoriality or both have been found in all dyads and groups of sympartic sibling bird species studied so far. In this study, we investigated the coexistence of three cryptic sibling species of the golden‐spectacled warblers Phylloscopus burkii complex in Hunan Province, China: Ph. tephrocephalus, Ph. omeiensis and Ph. valentini. We analyzed their habitat preferences, and spatial interrelations between the species. In order to analyze either presence or absence of interspecific territoriality, we additionally performed con‐ and heterospecific playback experiments. Contrary to expectations, we found no evidences for either habitat segregation or interspecific territoriality in these three species.     

Spatial segregation of sympatric marten and fishers: the influence of landscapes and species‐scapes

Co‐occurring species are rarely considered as a factor influencing habitat selection. However, niche theory predicts that sharing resources, predators, and other interspecific interactions can limit the environmental conditions under which a species may exist. How does the spatial distribution of one species affect that of another within shared landscapes? We tested whether sympatric marten Martes americana and fishers M. pennanti in a mountain landscape in Alberta, Canada exhibit local‐scale spatial segregation, beyond differential habitat selection. We modelled marten and fisher distribution in relation to remotely‐sensed habitat data and species co‐occurrence, using generalized linear models and information‐theoretic model selection. Marten and fishers selected different habitat types and showed different responses to habitat fragmentation. Even after accounting for these differences, the absence of one species significantly explained the occurrence of the other. We conclude that the spatial distribution of marten and fishers influences habitat selection by each other at landscape scales, and hypothesize that this pattern may result from competition in a spatially heterogeneous environment. Species‐habitat models that consider only resources may fail to capture key predictors of species’ occurrence. Reliable prediction and inference requires that ecologists expand from landscapes to also include species‐scapes: a spatial plane of species interactions that combines with resources to drive species’ distributions.     

Epiphytic lichens and bryophytes of forest ecosystems in Tuscany (Central Italy)

The distribution of epiphytic bryophytes and lichens on three species of trees (Quercus ilex, Quercus cerris and Fagus sylvatica, representing the forest ecosystems of central Italy at low, medium and high elevations, respectively) was examined with respect to host specificity and habitat differences. Although most species were host-specific, the results suggested that habitat characteristics are more important than phorophyte properties in determining the distribution of lichens and bryophytes. Factors affecting the diversity of the epiphytic flora were different for lichens and bryophytes. In the case of lichens, climatic parameters and forest monospecificity were important factors, whereas tree cover (i.e. shade) and to a certain extent the number of available trees seemed more important for bryophytes.