亚洲玉米螟两个不同地理种群对暗期干扰的滞育反应

为了探明亚洲玉米螟Ostrinia furnacalis (Guenée)不同地理种群对暗期干扰的滞育反应, 本文在研究了亚洲玉米螟南昌种群（28°41′N, 115°53′E）和哈尔滨种群（44°56′N, 127°10′E）光周期反应的基础上, 在室内分别测试了25℃和28℃温度下1 h的光脉冲干扰光周期L9∶D15和L12∶D12对这两个不同地理种群幼虫滞育抑制的影响。结果表明： 在25℃和28℃下, 哈尔滨种群的临界日长分别比南昌种群延长了1 h 40 min和2 h; 在所有测试的暗期干扰实验中, 除了极少数光脉冲干扰点外, 南昌种群幼虫滞育的发生率显著低于哈尔滨种群; 1 h光脉冲干扰光周期L9∶D15的滞育发生率明显低于干扰光周期L12∶D12, 且前者表现了暗期的中间对光脉冲最敏感, 而后者显示了暗期的初期对光脉冲最敏感; 28℃下光脉冲对滞育的抑制效果强于25℃。这些结果进一步提示, 即使在同种昆虫中, 如果地理种群和实验条件不同, 暗期干扰对滞育抑制的效果也可能不同。     

The limited spatial scale of dispersal in soil arthropods revealed with whole‐community haplotype‐level metabarcoding

Soil arthropod communities are highly diverse and critical for ecosystem functioning. However, our knowledge of spatial structure and the underlying processes of community assembly are scarce, hampered by limited empirical data on species diversity and turnover. We implement a high‐throughput sequencing approach to generate comparative data for thousands of arthropods at three hierarchical levels: genetic, species and supra‐specific lineages. A joint analysis of the spatial arrangement across these levels can reveal the predominant processes driving the variation in biological assemblages at the local scale. This multihierarchical approach was performed using haplotype‐level COI metabarcoding of entire communities of mites, springtails and beetles from three Iberian mountain regions. Tens of thousands of specimens were extracted from deep and superficial soil layers and produced comparative phylogeographic data for >1,000 codistributed species and nearly 3,000 haplotypes. Local assemblage composition differed greatly between grasslands and forests and, within each habitat, showed strong spatial structure and high endemicity. Distance decay was high at all levels, even at the scale of a few kilometres or less. The local distance decay patterns were self‐similar for the haplotypes and higher hierarchical entities, and this fractal structure was similar in all regions, suggesting that uniform processes of limited dispersal determine local‐scale community assembly. Our results from whole‐community metabarcoding provide insight into how dispersal limitations constrain mesofauna community structure within local spatial settings over evolutionary timescales. If generalized across wider areas, the high turnover and endemicity in the soil locally may indicate extremely high richness globally, challenging our current estimations of total arthropod diversity on Earth.     

Disparity between range map- and survey-based analyses of species richness: patterns, processes and implications

Species richness patterns are characterized either by overlaying species range maps or by compiling geographically extensive survey data for multiple local communities. Although, these two approaches are clearly related, they need not produce identical richness patterns because species do not occur everywhere in their geographical range. Using North American breeding birds, we present the first continent‐wide comparison of survey and range map data. On average, bird species were detected on 40.5% of the surveys within their range. As a result of this range porosity, the geographical richness patterns differed markedly, with the greatest disparity in arid regions and at higher elevations. Environmental productivity was a stronger predictor of survey richness, while elevational heterogeneity was more important in determining range map richness. In addition, range map richness exhibited greater spatial autocorrelation and lower estimates of spatial turnover in species composition. Our results highlight the fact that range map richness represents species coexistence at a much coarser scale than survey data, and demonstrate that the conclusions drawn from species richness studies may depend on the data type used for analyses.     

Influence of Different Stocking Rates on Plant Diversity of Artemisia frigida Community in Inner Mongolia Steppe

The experiment was conducted in Inner Mongolia steppe located in 43°26′-44° 08′N, 116°04′-117°05′ E in 1989-1997. The grazing experiment design was 5 stocking rates (0.00, 1.33, 2.67, 4.00, 5.33 and 6.67 sheep·hm-2, but 0.00, 1.33, 2.00, 2.67, 3.33 and 4.00 sheep·hm-2 in 1990) with three 1 hm2 rotational paddocks per treatment. The sheep were Inner Mongolia fine sheep and the experiment was performed during warm seasons every year from May 20 to October 5. The objectives were to research the integrated influence of different stocking rates on plant diversity and to provide knowledge of its mechanism by the method of continuous monitoring of 8 years for the same grazing experiment rather than through spatial gradient.The results showed that using the method of 100 m sample line was suitable for estimating the abundance of plant species. Simpson index and evenness were better parameters to measure the influence of different stocking rates on plant diversity for Artemisia frigida community. The plant species abundance almost remained unchanged, but the plant diversity and evenness decreased as the stocking rate increased, and the community dominance increased with stocking rate during the 8 years' grazing under different stocking rates. The interaction of the preferred ingestion of grazing sheep with heavy stocking rate may be one of the key reasons resulting in the decrease of plant diversity and evenness. Grass proportion decreased with the increase of stocking rates and A. frigida community degraded further into Potentilla acaulis community under heavy grazing or over-grazing. The succession and plant diversity of A. frigia community under different stocking rates mainly depend on the dynamics of A. frigida, Cleistogenes squarrosa, Potentilla acaulis, Agropyron cristatum and Carex duriuscula populations; Cleistogenes squarrosa population is one of the 3 populations of maximum abundance under all stocking rates from 1989 to 1997.     

广州珠江口海域中肋骨条藻的周年变化及其与环境因子的关系

2004年3月至2005年3月对广州海域(22°33′～22°41′N,113°37′～113°42′E)进行了调查研究,分析结果表明,广州海域中肋骨条藻数量的空间平面分布不均匀,分布格局呈内河口向外河口递增的趋势;中肋骨条藻数量的季节波动模式为单峰型;中肋骨条藻的密度与活性磷酸盐含量存在显著的负相关关系,与硅酸盐含量存在显著的正相关关系;与温度、盐度、亚硝酸盐、铵盐、透明度、硝酸盐、COD及pH的相关性不显著,但与DO存在一定的正相关性,但相关性均不显著;活性磷酸盐和硅酸盐是广州海域中肋骨条藻的主要影响因素。     

Regional scale patterns of fine root lifespan and turnover under current and future climate

Fine root dynamics control a dominant flux of carbon from plants and into soils and mediate potential uptake and cycling of nutrients and water in terrestrial ecosystems. Understanding of these patterns is needed to accurately describe critical processes like productivity and carbon storage from ecosystem to global scales. However, limited observations of root dynamics make it difficult to define and predict patterns of root dynamics across broad spatial scales. Here, we combine species‐specific estimates of fine root dynamics with a model that predicts current distribution and future suitable habitat of temperate tree species across the eastern United States (US). Estimates of fine root lifespan and turnover are based on empirical observations and relationships with fine root and whole‐plant traits and apply explicitly to the fine root pool that is relatively short‐lived and most active in nutrient and water uptake. Results from the combined model identified patterns of faster root turnover rates in the North Central US and slower turnover rates in the Southeastern US. Portions of Minnesota, Ohio, and Pennsylvania were also predicted to experience >10% increases in root turnover rates given potential shifts in tree species composition under future climate scenarios while root turnover rates in other portions of the eastern US were predicted to decrease. Despite potential regional changes, the average estimates of root lifespan and turnover for the entire study area remained relatively stable between the current and future climate scenarios. Our combined model provides the first empirically based, spatially explicit, and spatially extensive estimates of fine root lifespan and turnover and is a potentially powerful tool allowing researchers to identify reasonable approximations of forest fine root turnover in areas where no direct observations are available. Future efforts should focus on reducing uncertainty in estimates of root dynamics by better understanding how climate and soil factors drive variability in root dynamics of different species.     

Quantifying the influence of environmental texture on the rate of species turnover: evidence from two habitats

The environmental texture hypothesis (ETH) proposes that the spatial geometry or texture of the environment influences the rate at which species are accumulated in space or time. Specifically, the ETH suggests that regions, and spatial scales, that exhibit a larger rate of environmental distance decay (DD) should exhibit more rapid rates of species turnover. The ETH should apply over any range of scales where the environment is driving species distributions. To examine the relevance of the ETH at local spatial scales, we tested for a positive relationship between the rate of change in soil chemical properties and vascular plant species composition in grassland and woodland habitats. We recorded presence–absence data along a 1.883 km transect in each habitat and estimated the rate of turnover and environmental DD for spatial lags of 1–41 m. We found that the soil environment explained spatial patterns of species composition more accurately in the grassland habitat compared to the woodland habitat. Consequently the rate of change in soil properties as a function of spatial distance was significantly positively correlated with the rate of species turnover in the grassland but not the woodland. Our study suggests that one of the central premises of the ETH is relevant for local patterns of species turnover if the environment appears to influence species composition.     

Spatial predictability and resource specialization of bees (Hymenoptera: Apoidea) at a superabundant, widespread resource

For reciprocal specialization (coevolution) to occur among floral visitors and their host plants the interactions must be temporally and spatially persistent. However, studies repeatedly have shown that species composition and relative abundance of floral visitors vary dramatically at all spatial and temporal scales. We test the hypothesis that, on average, pollen specialist bee species occur more predictably at their floral hosts than pollen generalist bee species. Taxonomic floral specialization reaches its extreme among species of solitary, pollen-collecting bees, yet few studies have considered how pollen specialization by floral visitors influences their spatial constancy. We test this hypothesis using an unusually diverse bee guild that visits creosote bush (Larrea tridentatd), the most widespread, dominant plant of the warm deserts of North America. Twenty-two strict pollen specialist and 80 + generalist bee species visit Larrea for its floral resources. The sites we sampled were separated by 0.5 to > 1450 km, and spanned three distinct deserts and four vegetation zones. We found that species of Larrea pollen specialist bees occurred at more sites and tended to be more abundant than generalists. Surprisingly, spatial turnover was high for both pollen specialist and generalist bee species at all distances, and species composition of samples from sites 1–5 km apart varied as much as repeat samples made at single sites. Nevertheless, the pattern of bee species turnover was not haphazard. As distance among sites increased faunal similarity of sites decreased. Faunal similarities among sites within 250 km of each other were generally greater than if randomly distributed over all sites (the null model). No single ecological category of species (widespread, localized, Larrea pollen specialist, floral generalist) accounted for this spatial predictability. Evidently, concordant local distribution patterns of many ecologically diverse species contribute to the non-random spatial pattern. The ecological dominance of creosote bush does not confer obvious ecological advantages to its specialist floral visitors. Spatial turnover is comparable to that found for bee guilds from other biogeographic regions of the world and is not therefore limited to those bee species that inhabit highly seasonal climates, such as deserts. Philopatry and differences in bloom predictability among sites are probably more important causes for spatial turnover of bee species than are interspecific competition for nest sites or floral resources.     

Spatial turnover in the global avifauna

Despite its wide implications for many ecological issues, the global pattern of spatial turnover in the occurrence of species has been little studied, unlike the global pattern of species richness. Here, using a database on the breeding distributions of birds, we present the first global maps of variation in spatial turnover for an entire taxonomic class, a pattern that has to date remained largely a matter of conjecture, based on theoretical expectations and extrapolation of inconsistent patterns from different biogeographic realms. We use these maps to test four predictions from niche theory as to the form that this variation should take, namely that turnover should increase with species richness, towards lower latitudes, and with the steepness of environmental gradients and that variation in turnover is determined principally by rare (restricted) species. Contrary to prediction, we show that turnover is high both in areas of extremely low and high species richness, does not increase strongly towards the tropics, and is related both to average environmental conditions and spatial variation in those conditions. These results are closely associated with a further important and novel finding, namely that global patterns of spatial turnover are driven principally by widespread species rather than the restricted ones. This complements recent demonstrations that spatial patterns of species richness are also driven principally by widespread species, and thus provides an important contribution towards a unified model of how terrestrial biodiversity varies both within and between the Earth's major land masses.     

Temperature effects in relation to the patterns of distribution and abundance of three species in the Drosophila affinis subgroup

Abstract. 1. The effect of temperature on several aspects of the biology of Drosophila affinis, D.algonquin and D.athabasca were investigated in order to gain insight as to why these closely related species differ in their spatial and temporal patterns of occurrence.
2. No differences exist between the three species in the effect of temperature on egg hatchability.
3. Productivities of the three species were measured in a temperature gradient device. These measurements indicated that D.athabasca has an advantage in productivity over D.affinis at cooler temperatures (below 25°C). At warmer temperatures (above 25°C) the greater productivity of D.affinis makes it the better species. Drosophila algonquin , like D.athabasca , was characterized by its productivity curve as a species more adapted to cooler climates.
4. The competitive abilities of the three species were measured at 25°C, at 18°C, and in an environment which fluctuated between 18 and 25°C on a daily cycle. Competitive ability was estimated on the basis of the performance of the species in two- and three-species populations.
5. In general, D.affinis exhibited its highest competitive ability relative to the other two species at the highest experimental temperature. D.athabasca had its highest competitive ability at the lowest temperature. The competitive ability of Ddgonquin was intermediate; less than that of D.affinis but greater than D.athabasca .
6. The dependence of competitive ability and productivity on temperature is thought to be partly responsible for the differences between the species with respect to their geographic distributions and their spatial and temporal patterns in natural populations.     

高原鼠兔食物资源利用的研究

高原鼠兔(Ochatona curzoniae Hodgson)为青藏高原草场上的重要害鼠。每年都要投入很大的力量进行防治,因之它的生态学研究是非常必要的。草原上的初级生产--绿色植被是如何被高原鼠兔利用的就是一项重要的研究课题。皮南林(1975)曾在快尔玛地区研究过高原鼠兔的食性,并注意到食性与植物多度的关系。     

Fine‐scale patterns of species and phylogenetic turnover in a global biodiversity hotspot: Implications for climate change vulnerability

Question: What is the relative importance of environmental and spatial factors for species compositional and phylogenetic turnover? Location: High‐rainfall zone of the Southwest Australian Floristic Region (SWAFR). Methods: Correlates of species compositional turnover were assessed using quadrat‐based floristic data, and establishing relationships with environmental and spatial factors using canonical correspondence analyses and Mantel tests. Between‐quadrat phylogenetic distance measures were computed and examined for correlations with environmental and spatial attributes. Processes structuring pa2t2terns of beta diversity were also evaluated within four broad floristic assemblages defined a priori. Results: Floristic diversity was strongly related to environmental attributes. A low significance of spatial variables on assemblage patterns suggested no evident effect of dispersal limitations. Species compositional turnover was especially high within the swamp and outcrop assemblage. Phylogenetic turnover was closely coupled to species compositional turnover, implying the occurrence of many locally endemic and phylogenetically relict taxa. Beta diversity patterns within assemblages were also significantly correlated with the local environment, and relevant correlates differed between floristic assemblage types. Conclusion: Phylogenetic diversity in the SWAFR high‐rainfall zone is clustered within edaphic microhabitats in a generally subdued landscape. A clustered rather than dispersed distribution of phylogenetic diversity increases the probability of significant plant diversity loss during periods of climate change. Climate change susceptibility of the region's flora is accordingly estimated to be high. We highlight the conservation significance of swamp and outcrops that are characterized by distinct hydrological properties and may provide refugial habitat for plant diversity during periods of moderate climate change.     

血革螨属一新种记述及对鼯鼠真厉螨 雌性形态原始描述的更正（蜱螨亚纲：血革螨科）

 记述血革螨属Haemogamasus Berlese, 1889一新种,后凹血革螨H.postsinuatus sp. Nov.,采于湖北西北部神农架自然保护区的食虫目（Insectivora）。 另对鼯鼠真厉螨Eulaelaps petauristae Liu et Ma, 1998 雌性气门沟原始描述 进行更正。     

Species turnover in lake littorals: spatial and temporal variation of benthic macroinvertebrate diversity and community composition

Aims Despite wide consensus that ecological patterns and processes should be studied at multiple spatial scales, the temporal component of diversity variation has remained poorly examined. Specifically, rare species may exhibit patterns of diversity variation profoundly different from those of dominant taxa. Location Southern Finland. Methods We used multiplicative partitioning of true diversities (species richness, Shannon diversity) to identify the most important scale(s) of variation of benthic macroinvertebrate communities across several hierarchical scales, from individual samples to multiple littorals, lakes and years. We also assessed the among‐scale variability of benthic macroinvertebrate community composition by using measures of between‐ and within‐group distances at hierarchical scales. Results On average, a single benthic sample contained 23% of the total regional macroinvertebrate species pool. For both species richness and Shannon diversity, beta‐diversity was clearly the major component of regional diversity, with within‐littoral beta‐diversity (β₁) being the largest component of gamma‐diversity. The interannual component of total diversity was small, being almost negligible for Shannon index. Among‐sample (within‐littoral) diversity was related to variation of substratum heterogeneity at the same scale. By contrast, only a small proportion of rare taxa was found in an average benthic sample. Thus, dominant species among lakes and years were about the same, whereas rare species were mostly detected in a few benthic samples in one lake (or year). For rare species, the temporal component of diversity was more important than spatial turnover at most scales. Main conclusions While individual species occurrences and abundances, particularly those of rare taxa, may vary strongly through space and time, patterns of dominance in lake littoral benthic communities are highly predictable. Consequently, many rare species will be missed in temporally restricted samples of lake littorals. In comprehensive biodiversity surveys, interannual sampling of littoral macroinvertebrate communities is therefore needed.     

Phase transitions in sphingomyelin thin filsm. A spin label study

3-Spiro-(2′-(N-oxyl-4′,4′-dimethyloxazolidine)) — cholestane, (I) and 12-spiro-(2′-(N-oxyl-4′,4′-dimethyloxazolidine))-stearic acid (II) have been used as molecular probes to study the interaction of sphingomyelin and cholesterol in both dry and hydrated oriented films at different temperatures. The presence of 50 mole percent cholesterol causes a gel to liquid crystalline phase transition of bovine brain sphingomyelin at 20°C. A temperature induced phase transition involving the phospholipid polar groups has been detected. The mean transition temperature from a rigid to a fluid bilayer lattice structure is 32°C ±0.5°C in hydrated equimolar sphingomyelin — cholesterol films.     

Partitioning the turnover and nestedness components of beta diversity

Aim  Beta diversity (variation of the species composition of assemblages) may reflect two different phenomena, spatial species turnover and nestedness of assemblages, which result from two antithetic processes, namely species replacement and species loss, respectively. The aim of this paper is to provide a unified framework for the assessment of beta diversity, disentangling the contribution of spatial turnover and nestedness to beta-diversity patterns.
Innovation  I derive an additive partitioning of beta diversity that provides the two separate components of spatial turnover and nestedness underlying the total amount of beta diversity. I propose two families of measures of beta diversity for pairwise and multiple-site situations. Each family comprises one measure accounting for all aspects of beta diversity, which is additively decomposed into two measures accounting for the pure spatial turnover and nestedness components, respectively. Finally, I provide a case study using European longhorn beetles to exemplify the relevance of disentangling spatial turnover and nestedness patterns.
Main conclusion  Assigning the different beta-diversity patterns to their respective biological phenomena is essential for analysing the causality of the processes underlying biodiversity. Thus, the differentiation of the spatial turnover and nestedness components of beta diversity is crucial for our understanding of central biogeographic, ecological and conservation issues.     

Phytoplankton distribution in the upwelling areas of the Moroccan Atlantic coast localized between 32°30'N and 24°N

Marine phytoplankton was studied in January and July 2002 along of four transects: 32°30′N, 29°N, 24°30′N and 24°N. A total of 142 taxa were recorded in this area. The maximal specific richness, both in summer and in winter, was registered around Dakhla (24°N). The global spatiotemporal variability of species richness and specific diversity showed that the most structured and species-rich populations are situated in the coastal areas. The vertical variation of the two parameters showed homogeneity between depth levels. The maximal phytoplanktonic densities are recorded in the southern transects due to the permanent upwelling activity in the southern Atlantic coast. The bathymetric distribution of densities was more heterogeneous during summer, characterized by a high intensity of upwelling. The species Thalassionema nitzschioides, Asterionellopsis glacialis, Melosira, Chaetoceros and Leptocylindrus minimus are indicators of upwelling.     

Scale dependency of diversity components estimated from primary biodiversity data and distribution maps

Different sources of information about biodiversity may lead to unrealistic or biased estimation of its components, with different patterns according to the scale of analysis. In this study, we analyse patterns of species richness at the local (average alpha) and regional (gamma) scales, and the relationship between them (Whittaker's beta), in central Mexico, using as a source of data for the species' distributions: (1) museum specimen occurrence data for birds, and (2) distribution maps based on ecological niche models developed and refined by experts. We performed analyses at five spatial resolutions (1/32°−1/2°). Scale changes (grain and extent) affected significantly the estimates of average alpha, gamma, and beta. Use of raw occurrence data vs. distribution maps yielded contrasting results, with raw data underestimating alpha and overestimating beta, as functions of area. As regards species–area relationships, our results suggest a natural decomposition of factors into an area-invariant component (related to alpha), and an area dependent factor (related to beta). Most of our results are maintained in a null model that randomizes occurrences without changing observed range-size distributions. From this result we argue that average alpha and Whittaker's beta capture little information about the spatial covariation of species distribution patterns.     

Trends in aquatic macrophyte species turnover in Northern Ireland — which factors determine the spatial distribution of local species turnover?

Aim The study examined qualitative predictions of ecological theories in relation to the spatial distribution of species turnover of aquatic macrophytes, through the following parameters: (1) distance between lakes (2) chemical conditions of the lakes (3) chemical differences between the lakes, and (4) the lake size. Location 562 lakes dispersed throughout Northern Ireland were analysed. Methods To obtain species turnover estimates independent of richness, the average distance between focal lakes and their five nearest neighbours in ordination space (DCA) was standardized by the species richness in a Generalized Additive Model (GAM). The relationships between species turnover and ecological (chemical condition, chemical difference, distance between lakes, and lake‐size) and geographical parameters (latitude, longitude, and altitude) were analysed using GAM. Results The results indicate that the pattern in species turnover is a combination of the chemical conditions and the distance between the lakes, including the interaction term. The effects of chemical heterogeneity and lake size parameters were both positive but weak. In general, increased distance and decreased ionic concentration contribute to increased turnover. The influence of distance on species turnover is strongest at low and high altitude, and at mid‐elevation the species turnover is mainly driven by the chemical conditions. Towards the north there is an increasing influence of distance, whereas in the south the chemical conditions have their strongest influence. Conclusions There is a need for components from several established ecological theories to explain the spatial trends in species turnover within Northern Ireland. Central theories in this particular study are the population/metapopulation dynamics, the continuum concept, and the species‐pool concept.     

Dispersal,niche, and isolation processes jointly explain species turnover patterns of nonvolant small mammals in a large mountainous region of China

Understanding the mechanisms that govern the spatial patterns of species turnover (beta diversity) has been one of the fundamental issues in biogeography. Species turnover is generally recognized as strong in mountainous regions, but the way in which different processes (dispersal, niche, and isolation) have shaped the spatial turnover patterns in mountainous regions remains largely unexplored. Here, we explore the directional and elevational patterns of species turnover for nonvolant small mammals in the Hengduan Mountains of southwest China and distinguish the relative roles of geographic distance, environmental distance, and geographic isolation on the patterns. The spatial turnover was assessed using the halving distance (km), which was the geographic distance that halved the similarity (Jaccard similarity) from its initial value. The halving distance was calculated for the linear, logarithmic, and exponential regression models between Jaccard similarity and geographic distance. We found that the east–west turnover is generally faster than the south–north turnover for high‐latitudinal regions in the Hengduan Mountains and that this pattern corresponds to the geographic structure of the major mountain ranges and rivers that mainly extend in a south–north direction. There is an increasing trend of turnover toward the higher‐elevation zones. Most of the variation in the Jaccard similarity could be explained by the pure effect of geographic distance and the joint effects of geographic distance, environmental distance, and average elevation difference. Our study indicates that dispersal, niche, and isolation processes are all important determinants of the spatial turnover patterns of nonvolant small mammals in the Hengduan Mountains. The spatial configuration of the landscape and geographic isolation can strongly influence the rate of species turnover in mountainous regions at multiple spatial scales.