Home range area in the tortoise Testudo hermanni in relation to habitat complexity: implications for conservation of biodiversity

The tortoise Testudo hermanni is endangered by habitat fragmentation and loss in western Europe, where its high public profile and specific conservation projects make this a flagship species. Studies of movement in the peak reproductive season (June) showed that home ranges were substantially larger in France than in Greece. This difference was due to the intensity of use of the home range, not to the distance moved which was remarkably similar in the two areas. There was no sexual difference in home range area. The home range was therefore not large in France because of movement to nesting sites, but rather for utilization of the greater habitat complexity there. The need for reserves to include different vegetation types makes conservation of T. hermanni in France more difficult. Conversely, the need for large reserves increases its value as an umbrella species for conservation of biodiversity.     

Echolocation calls of Rhinolophus ferrumequinum in relation to habitat type and environmental factors

The present experiment was carried out in Luotong Mountain Natural Reserve in Jilin Province of China in 2007. We recorded and analyzed the echolocation calls of Rhinolophus ferrumequinum in different habitats by using Avisoft Bioacoustics USG 116 and Avisoft-SASLAB PRO (Avisoft Bioacoustics, Berlin, Germany). Our results showed that R. ferrumequinum foraged in diverse habitats in the study area, and their echolocation calls were significantly variable in different habitats (One-Way ANOVA, P < 0.05). Vegetative, climatic and topographical factors were selected by using the principal component analysis and the correlations between the parameters of echolocation calls and these environmental factors were analyzed. The results indicated that although R. ferrumequinum always emitted FM/CF/FM echolocation calls in different habitats, the parameters of echolocation calls varied with variable environmental factors. Significant negative correlation existed between FM1 bandwidth and arbor height (r = ?0.948, P < 0.05), FM₂ bandwidth and arbor height (r = ?0.825; P < 0.05), FM1 starting frequency and canopy area (r = ?0.967, P < 0.05), FM₂ ending frequency and canopy area (r = ?0.958, P < 0.05), FM1 starting frequency and air relative humidity (r = ?0.776, P < 0.05), FM₂ ending frequency and air relative humidity (r = ?0.875, P < 0.05), peak frequency and air relative humidity (r = ?0.794, P < 0.05), pulse duration and average shrub height (r = ?0.911, P < 0.05), and inter-pulse interval and average shrub height (r = ?0.990, P < 0.05). Significant positive correlation existed between peak frequency and number of plants (r = 0.756, P < 0.05), and pulse duration and height below the canopy (r = 0.870, P < 0.05). Our results suggested that many kinds of ecological factors (such as vegetation factor, climatic factor and topographical factor) affected the structure of echolocation calls and made them diverse in different habitats, i.e., echolocation calls of bats had phenotypic flexibility and eco-adaptability. These characteristics determined the degree of available habitats and natural resources for R. ferrumequinum.     

Biological traits of stream macroinvertebrates from a semi-arid catchment: patterns along complex environmental gradients

1. The relationships between biological traits of macroinvertebrates and environmental characteristics were investigated in streams with contrasting physical, chemical or landscape level attributes. We used an ordination technique, RLQ analysis, which links an environmental table (R) with traits table (Q) through an abundance table (L) to investigate the relationship between habitat characteristics and biological traits.
2. A major environmental axis explaining the distribution of species and their distinctive biological features was obtained. This axis included variables of anthropogenic pressure (agricultural and urban uses) and natural variability (climatic and geologic) that are strongly intercorrelated in the study area, with a clear spatial component.
3. The attributes of species from frequently disturbed systems (small size, multivoltinism, diapause, ovoviviparity, etc.) were associated with semi-arid areas whereas traits common in more stable and favourable environments (large body size, semi-voltinism, isolated eggs, etc.) were found in upland forested areas.
4. The natural climatic variation was proposed as a disturbance axis of a theoretical habitat templet (driven by the intense hydrological disturbances typical of semi-arid streams), while anthropogenic pressure (mainly intensive agriculture) and high salinity, a natural consequence of geology, was proposed as an adversity axis. Different life-histories associated with contrasting environmental features were superimposed in this habitat templet.
5. The ecological–evolutionary scenario in which stream macroinvertebrates have evolved and by which their communities are organized, is closely linked to disturbance, environmental harshness and human pressure.     

黄土高原丘陵区不同生境小叶杨人工林物种多样性及其群落稳定性分析

通过样地调查,对黄土高原丘陵沟壑区处于阴坡、半阴坡、半阳坡、阳坡4种生境条件下,经过30年发育的小叶杨人工林物种多样性,群落结构动态和土壤水分养分效应进行了系统研究,结果表明:(1)不同生境小叶杨人工林总体上物种丰富度、多样性指数和均匀度指数均呈现出阴坡>半阴坡>半阳坡>阳坡的趋势,且林内物种多样性指数表现为:草本层>灌木层;(2)不同生境条件下的小叶杨人工林年龄结构分析表明,尽管阴坡小叶杨长势相对较好,但更新幼苗数量相当有限,很难实现种群的自我更新,不适合作为人工林培育;(3)土壤含水量和养分因坡向不同而呈现出明显的差异,尽管阴坡和半阴坡的水分、养分条件相对较好,但也出现了枯梢、病虫害等衰老特征,因此阴坡、半阴坡的生境对小叶杨来说也不合适.未来应该对现有林地在保护的前提下,间伐衰老个体,补植和引入乡土物种,进行天然化培育.     

Influence of galls of Phanacis taraxaci on carbon partitioning within common dandelion, Taraxacum officinale

We examined how leaf galls, induced by the cynipid wasp Phanacis taraxaci, influence the partitioning of photoassimilates within the host, the common dandelion, Taraxacum officinale. Galled and ungalled plants were exposed to ¹⁴CO₂ and the labelled photoassimilates accumulating within galls and other parts of the host were measured. During the growth phase of the gall they were physiological sinks for photoassimilates, accumulating 9% to 70% of total carbon produced by the host, depending upon the number of galls per plant. High levels of ¹⁴C assimilation in the leaves of galled plants compared to controls, suggest that galls actively redirect carbon resources from unattacked leaves of their host plant. This represents a significant drain on the carbon resources of the host, which increases with the number and size of galls per plant. Active assimilation of ¹⁴C by the gall is greatest in the growth phase and is several orders of magnitude lower in the maturation phase. This finding is consistent with physiological and anatomical changes that occur during the two phases of gall development and represents a key developmental strategy by cynipids to ensure adequate food resources before larval growth begins.     

扩散对破碎化景观上宿主-寄生种群动态的影响

景观破碎化和扩散是空间种群模型的重要因素,对生物入侵存在着深远的影响。本章将基于偶对近似模型,探讨由局部和全局宿主-寄生相互作用共同决定的扩散模式对破坏性景观上疾病入侵与传播的影响。其中,生境破坏由生境丧失量与生境破碎化程度来描述。模拟结果显示,宿主和病毒的全局扩散对疾病的入侵与种群密度产生不对称效应：病毒的全局扩散对系统产生的影响较宿主的全局扩散更为显著。不同扩散模式下,生境丧失越高或破碎化程度越低,均将越有害于寄生病毒的入侵;同时,生境的破坏程度也显著地影响了入侵阈值对扩散模式的响应机制。本文研究结果暗示,景观破碎化的空间分布格局以及病毒扩散的限制均可作为物种保护与管理中有效的疾病控制策略。该研究结果在一定意义上丰富和发展了寄生感染理论,为物种保护提供了生态学理论依据。     

Extraction of peroxidase from bitter gourd (Momordica charantia) by three phase partitioning with dimethyl carbonate (DMC) as organic phase

Three phase partitioning (TPP) is most renowned technique used for extraction and purification of natural products. In previous studies of TPP, t-butanol is mainly used as an organic phase. This is the first report that explores ability of dimethyl carbonate (DMC) in the field of TPP as an alternate solvent for t-butanol. In the present study TPP process with t-butanol and DMC as organic phase along with different salts was applied to waste bitter gourd powder to obtained peroxidase enzyme. DMC was found to be compatible with most of salts such as ammonium sulphate and sodium citrate and explored as more efficient solvent than t-butanol. This TPP system provides 4.84 fold purity of peroxidase enzyme at optimum source concentration of 0.15 g/mL, with a system comprising DMC as organic phase, sodium citrate (20%) as salt, agitation speed 120 rpm, pH 7, temperature 30 °C and extraction time of 3 h. Present study has aimed for extraction and separation of peroxidase from bitter gourd waste with TPP technique and ensures the scope of carbonated solvents in extraction and purification of proteins.     

Disturbance affects spatial patterning and stand structure of a tropical rainforest tree

The distribution and spatial patterns of plant populations in natural ecosystems have recently received much attention; yet the impacts of human‐induced disturbances on these patterns and underlying processes remain poorly understood. We used the sub‐canopy tree, Ryparosa kurrangii (Achariaceae), to explore the possible effects of such disturbances on stand structure and spatial patterning in an Australian tropical rainforest. We studied three populations that differed in their extent of habitat modification: anthropogenic disturbance (proximate settlement and roads) and internal damage by an invasive alien species, the feral pig (Sus scrofa). Populations were mapped, characterized, and three size cohorts (seedlings, saplings, trees) were analysed using a suite of spatial point pattern analyses (univariate: Diggle's G and F and Ripley's K; bivariate: Diggle's G and Ripley's K). Ryparosa kurrangii has a typical stand structure for a sub‐canopy tree species, but occurs at high densities locally (>400 stems ha^?1). At all sites, the tree cohort were randomly distributed and saplings were spatially aggregated at distances of up to 2–3 m. Between sites there were distinct differences in the size structure and spatial pattern of seedlings, the cohort most affected by recent habitat modification. That is, the least disturbed site had no aggregation among seedlings, the site with the greatest anthropogenic disturbance had many small, clustered seedlings that were spatially associated with trees, and the site with pig damage had clustered seedlings that had no spatial relationship with trees. We propose that habitat modification by anthropogenic and pig disturbance disrupts seed dispersal and establishment regimes, which leads to altered seedling spatial patterns. These disturbances could have long‐term implications for the population structure and health of R. Kurrangii.     

Mind the gap: treefalls as drivers of parental trade‐offs

Tree‐fall gaps are small‐scale disturbances whose formation, colonization, and role in forest dynamics are well documented, but whose effects on animal ecology are still greatly overlooked, except for studies comparing species richness of gaps 6+ months old to that in the closed canopy. Other factors associated with the invasion of fresh tree‐fall gaps such as animal breeding adaptations have been largely neglected. I studied the immediate (within hours and days) arrival of the poison frog Dendrobates tinctorius in new tree‐fall gaps to examine the dynamics of their invasion in relation to tadpole rearing. I found that rearing sites are occupied sooner and tadpoles deposited at higher rates in fresh gaps than in the closed forest, but that the rate of cannibalism is also much greater in the former. This suggests that invading new tree‐fall gaps can be the best parental decision when parents arrive early because they get access to fresh, high‐quality resources, but it could be to the detriment of the offspring if parents arrive late, because of overcrowding and cannibalism. These results highlight the importance of studying the earliest stages of invasions in order to have a better understanding of the composition of communities in disturbed ecosystems at later successional stages.