The island rule: An assessment of biases and research trends

Aim

The island rule has been widely applied to a range of taxonomic groups, with some studies reporting supporting evidence but others questioning this hypothesis. To bring more clarity to this debate, we conducted a comparative analysis of the available literature, focussing on potential biases.

Location

Worldwide.

Methods

We performed a systematic review to identify studies testing the island rule and translated these studies’ outcomes, so that they follow a consistent approach. The studies were assessed for differences in their analysis of the island rule. We created an authorship network showing who published studies with whom on the topic and weighted the data based on co‐authorship and number of publications.

Results

We identified 143 relevant studies, finding a significantly lower frequency of supporting studies according to our consistent approach (50%) than the authors’ own statements (59%). Two core‐author groups could be identified with a strong publication record on the island rule. The first group has predominately published studies supporting the rule, whereas the other group has mainly published studies questioning it. According to a subsequent analysis excluding studies with a high risk of HARKing (hypothesizing after the results are known), the frequency of studies supporting the rule further dropped to 42%.

Main conclusions

Empirical support for the island rule is low, especially for non‐mammalian taxa and when using a consistent evaluation approach. Differences among studies in supporting versus questioning this hypothesis seem to be partly due to author‐related biases. Methods to address potential biases in studying ecological hypotheses are urgently needed. We offer such a method here.     

Ozone effects on plants in natural ecosystems

Tropospheric ozone (O₃) is an important stressor in natural ecosystems, with well‐documented impacts on soils, biota and ecological processes. The effects of O₃ on individual plants and processes scale up through the ecosystem through effects on carbon, nutrient and hydrologic dynamics. Ozone effects on individual species and their associated microflora and fauna cascade through the ecosystem to the landscape level. Systematic injury surveys demonstrate that foliar injury occurs on sensitive species throughout the globe. However, deleterious impacts on plant carbon, water and nutrient balance can also occur without visible injury. Because sensitivity to O₃ may follow coarse physiognomic plant classes (in general, herbaceous crops are more sensitive than deciduous woody plants, grasses and conifers), the task still remains to use stomatal O₃ uptake to assess class and species’ sensitivity. Investigations of the radial growth of mature trees, in combination with data from many controlled studies with seedlings, suggest that ambient O₃ reduces growth of mature trees in some locations. Models based on tree physiology and forest stand dynamics suggest that modest effects of O₃ on growth may accumulate over time, other stresses (prolonged drought, excess nitrogen deposition) may exacerbate the direct effects of O₃ on tree growth, and competitive interactions among species may be altered. Ozone exposure over decades may be altering the species composition of forests currently, and as fossil fuel combustion products generate more O₃ than deteriorates in the atmosphere, into the future as well.     

Long-term ecological research on Korean forest ecosystems: the current status and challenges

The present study aims to monitor the long-term changes in forest structure, productivity, nutrient cycling, and to accumulate ecological information on forest ecosystem in Korea. There are six long-term ecological research sites and seven flux measurement sites in Korea. The Gwangneung experimental forest (GEF) located in the central cool-temperate forest sub zone is known as a model site where many interdisciplinary researches have been ongoing actively since mid-1990s over all other Korea long-term ecological research sites (KLTER). Collected data and information through monitoring and investigation of changes in forest ecosystem have been stored in a database for analyses. The relative importance of tree species (%) of GEF was in the order Quercus serrata (20)?=?Euonymus oxyphyllus (20)?>?Carpinus laxiflora (12). The total biomass and basal area were 249.53 t ha^?1 and 26.66 m² ha^?1, respectively. There were 136 taxa with 49 families, with 97 genera, 11 varieties, 3 forma, and 1 subspecies in 1 ha permanent plot. The increase in temperature has been estimated to have negative effects on tree growth. The litter decomposition rate was in the order Cornus controversa?<?C. cordata?<?C. laxiflora?<?Q. serrata. The average litterfall and soil respiration were 5803 kg ha^?1 and 8600 kg C ha^?1, respectively. Further, the GEF, a KLTER site tended to be almost carbon neutral with an annual growth average of 51,000?±?78,000 kg ha^?1. The data from six LTER sites are digitalized and classified to build data catalogs on the ecological information system. The information on stand dynamics and materials and energy budget in the forest ecosystem is utilized for impact assessment and the study of adaptation strategy for forest ecosystem to climate change.     

Fumonisins: current research trends in developmental toxicology

Fumonisin B₁ (FB₁) is a mycotoxin produced byFusarium verticillioides that is found in maize and maize-based foods. Reproductive studies in CD1 mice, rats and rabbits initially found no evidence that fumonisins are teratogenic. However, more recent findings suggest that they might increase the risk of neural tube defects (NTDs) in populations consuming large amounts of fumonisin-contaminated corn. When ≥15 mg/kg body weight fumonisin B₁ (FB₁) was given to pregnant LM/Bc mice by intraperitoneal (ip) injection, all litters were positive for NTDs. To determine if NTD induction is unique to the inbred LM/Bc mouse strain, NTD induction in LM/Bc and CD1 mice was compared: (a) in a study in whichF. verticillioides culture material providing ≤150 ppm FB₁ was fed to female mice before and during gestation, and (b) in a study in which FB₁ was given by ip injection to CD1 dams on gestation days 7 and 8, the critical time for NTD development. In the feeding study, one of five LM/Bc litters from dams fed the 150 ppm FB₁ diet was positive for NTDs whereas no NTDs were found in the CD1 litters. In the ip injection study, 40% of the litters at the highest dose tested, 45 mg/kg body weight, were positive for NTDs and one of nine low-dose (15 mg/kg body weight) litters was also positive. Thus, FB₁ induced NTDs in both LM/Bc and CD1 mice although the latter strain appears less sensitive. Comparative investigations using these strains will be useful for elucidating the mechanisms underlying fumonisin-induced NTDs in mice and determining the suitability of mouse models for studying the relationships between fumonisins and NTDs in humans.     

The rhythmic structure of the human EEG: the current state and trends of the research

During the past decade, spectral analysis has become indispensable instrument for different kinds of EEG processing. With the development of dedicated computer system, investigation of shifts in human EEG rhythm under various conditions has improved considerably. However, it is difficult to make general conclusions from this line of research, since a large number of studies are carried out using the ambiguous experimental approaches and different methods. Present paper aims to evaluate a modern state of the art in the field of human EEG rhythmical structure investigation. The results from recent relevant articles are briefly reviewed according to the universal scheme (EEG rhythm--experimental condition--observed effect). Due to such presentation, the obtained results have been summarized and some tendencies of modern investigations have been revealed. The extension of studied frequency range of rhythmical EEG components to both high (> 35 Hz) and low (< 1 Hz) frequencies, the shift to a more detailed spectral structure analysis simultaneously with ignoring the fixed boundaries of traditional EEG rhythms, the growing attempts to reveal EEG rhythmical structure correlates of cognitive activity, and a wide utilization of dynamic approaches for the analysis of brain electrical activity are discussed in some detail. The observed data are indicate of high functional significance and perspectives of human EEG rhythmical structure investigation.     

Grassland ecosystems in China: review of current knowledge and research advancement

Grasslands are the dominant landscape in China, accounting for 40% of the national land area. Research concerning China's grassland ecosystems can be chronologically summarized into four periods: (i) pre-1950s, preliminary research and survey of grassland vegetation and plant species by Russians, Japanese and Western Europeans, (ii) 1950-1975, exploration and survey of vegetation, soils and topography as part of natural resource inventory programmes by regional and national institutions mainly led by the Chinese Academy of Sciences, (iii) 1976-1995, establishment of field stations for long-term ecological monitoring and studies of ecosystem processes, (iv) 1996-present, comprehensive studies of community dynamics and ecosystem function integrating multi-scale and multidisciplinary approaches and experimental manipulations.Major findings of scientific significance in China's grassland ecosystem research include: (i) improved knowledge on succession and biogeochemistry of the semi-arid and temperate grassland ecosystems, (ii) elucidation of life-history strategies and diapause characteristics of the native grasshopper species as one of the key grassland pests, and (iii) development of effective management strategies for controlling rodent pests in grassland ecosystems. Opportunities exist for using the natural grasslands in northern China as a model system to test ecosystem theories that so far have proven a challenge to ecologists worldwide.     

Floristic quality assessment signals human disturbance over natural variability in a wetland system

A common concern regarding the popular Floristic Quality Assessment (FQA) method is whether the site floristic quality scores change with natural temporal and site-specific variability. The more ignored question is whether this background variability will confound the index of human disturbance. Using non-forested seasonal wetlands in the northeastern United States, we tested if two common indices of site floristic quality (FQAI, Mean CoC) provide clear signals of site condition relative to gradients of wetland area and surface water depth, and consistent signals across time of year (early vs. late growing season), geomorphic setting (connected vs. isolated), and vegetation community type (pine barrens vernal pond, wet sedge meadow, shrub swamp). Mean CoC is the coefficient of conservatism (a qualitative estimate of species’ sensitivity to human disturbance) averaged across the native and exotic taxa observed at a given site, and FQAI is the traditional Floristic Quality Assessment Index where Mean CoC is multiplied by square root of taxa richness. The FQAI did not linearly correspond to the site condition gradient and thus it could not be evaluated. Mean CoC was clearly associated with site condition, with no interference from wetland area or water level (based on computer-intensive resampling of linear model fit). Mean CoC also varied consistently with site condition between the surveys, geomorphic settings, and community types (based on computer-intensive resampling of linear model slope). However, connected wetlands showed inherently greater Mean CoC than isolated wetlands, suggesting a comparison of floristic quality between these categories would not be prudent. Overall this study suggests that FQA in the form of Mean CoC may withstand natural variability in certain non-forested wetland systems. Instead of assuming FQA is overly sensitive to natural variability, we recommend further efforts to identify situations in which FQA is robust.     

The current status of ethnobiological research in Latin America: gaps and perspectives

Background

Recent reviews have demonstrated an increase in the number of papers on ethnobiology in Latin America. Among factors that have influenced this increase are the biological and cultural diversity of these countries and the general scientific situation in some countries. This study aims to assess the panorama of ethnobiological research in Latin America by analyzing its evolution, trends, and future prospects.

Methods

To conduct this study, we searched for papers in the Scopus (http://www.scopus.com) and Web of Science (http://www.isiknowledge.com) databases. The search was performed using combinations of keywords and the name of each Latin American country. The following countries were included in this study: Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Ecuador, Guatemala, Haiti, Honduras, Mexico, Panama, Paraguay, Peru, Venezuela, and Uruguay.

Results and conclusions

According to our inclusion criteria, 679 ethnobiological studies conducted in Latin America were found for the period between 1963 and 2012. Of these studies, 289 (41%) were conducted in Brazil, 153 in Mexico (22%), 61 in Peru (9%), 58 in Argentina (8%), 45 in Bolivia (6%), and 97 (14%) in other Latin American countries. The increased number of publications related to this area of knowledge in recent years demonstrates the remarkable growth of ethnobiology as a science. Ethnobiological research may be stimulated by an increase in the number of scientific events and journals for study dissemination and by the creation of undergraduate courses and graduate programs to train ethnoscientists who will produce high-quality studies, especially in certain countries.

     

Arboreal tropical forest vertebrates: current knowledge and research trends

We review the ecology and specialized methods required for studying arboreal mammals, birds, reptiles and amphibians, and use faunal checklists from 12 tropical wet forest sites and an analysis of all articles published during the past ten years in 14 major journals to assess current knowledge and general research trends for these groups. The percentage of arboreal vertebrates was remarkably similar at the different sites (76.2 ± 3.9%). Birds were the most arboreal group and amphibians and reptiles the least. The review of journals showed that primates were overwhelmingly the most studied group (336 papers), followed by bats (105), passeriform birds (73) and rodents (55). Judging by their portion of the arboreal vertebrate community and the number of papers surveyed, birds and amphibians and reptiles are vastly understudied compared to mammals, but this is largely due to the great number of primate studies. The number of publications on arboreal vertebrates has remained relatively stable over the last 10 years for all taxa except primates, which have seen a growth in publications. Canopy vertebrates from Brazil had by far the most publications (120), followed by Madagascar (61), Costa Rica (55) and Indonesia (42). We conclude by highlighting the priorities we see for future studies on tropical canopy vertebrates.     

Ecological risks in anthropogenic disturbance of nitrogen cycles in natural terrestrial ecosystems

Anthropogenic addition of reactive nitrogen (Nr) to the biosphere is increasing globally and some terrestrial ecosystems are suffering from a state of excess Nr for biological nitrogen (N) demand, termed N saturation. Here, we review the ecological risks in relation to N saturation and prospective responses to N saturation. Excess Nr increases the risks of local extinction of rare plant species, encouragement of exotic plant species, disturbance of nutrient balance in plant organs, and increase of herbivory in plant communities. On the ecosystem scale, excess bioavailable N induces forest decline, disturbance of nutrient cycling within ecosystems, depending on vegetation, soil, land-use, and N-loading history. These Nr risks will increase in the Asian region, where impacts of Nr in natural terrestrial ecosystems have been scarcely studied. Whether much of the terrestrial ecosystems on a global level are in the sate of N saturation or not is still controversial, but the potential risks of excess Nr seem to be increasing. The fundamental ways to mitigate Nr risks are to reduce Nr production, prevent Nr translocation, and promote conversion of Nr to N₂. Temporal, but promising actions against ecological N risks may include management of forests and riparian zones, and carbon addition in grassland.     

Anthropogenic EMF effects on the condition and function of natural ecosystems

A review of Russian and foreign studies of EMF effects on living environment was made. Vast range of EMF frequencies and intensities affect on functions and condition of ecosystems. Even non-thermal EMF levels could cause reversible changes in physiological process regulation. Some changes were observed in animal behavior such as motive activity, spatial orientation, reduction of ability to form a conditioned response. Some animal species (some insects, birds, reptiles) use electromagnetic fields for spatial orientation during migration. Biological communities are very sensitive to EMF effects and could become the biological indicators of electromagnetic pollution.     

甲虫形态学研究现状及态势分析

为了解甲虫形态学的研究概况和发展趋势,本文检索Zoological Record(ZR)数据库中该领域的研究论文,利用Thomson Data Analyzer(TDA)分析工具进行统计分析和数据挖掘。分析表明,该研究在20世纪六七十年代得到了快速发展,近十年以来,数量又有所增加。从事该研究的主要国家有美国、德国、日本、中国、法国等,热点主要内容集中在翅、生殖系统、结构大小、触角、口器等方向。新方法应用的领域各不相同,几何形态学和TEM的发文量较多,其次为显微CT和三维重建,MRI、CLSM、FIB/SEM发文量较少。甲虫形态学研究进入了一个新的发展阶段,显微CT、计算机三维重建、几何形态学等新方法的作用越来越突出。中国的研究数量表现不俗,但是论文影响力较弱,相关研究有待深入。     

Molecular ecology studies of species radiations: current research gaps,opportunities and challenges

Understanding the drivers and limits of species radiations is a crucial goal of evolutionary genetics and molecular ecology, yet research on this topic has been hampered by the notorious difficulty of connecting micro‐ and macroevolutionary approaches to studying the drivers of diversification. To chart the current research gaps, opportunities and challenges of molecular ecology approaches to studying radiations, we examine the literature in the journal Molecular Ecology and revisit recent high‐profile examples of evolutionary genomic research on radiations. We find that available studies of radiations are highly unevenly distributed among taxa, with many ecologically important and species‐rich organismal groups remaining severely understudied, including arthropods, plants and fungi. Most studies employed molecular methods suitable over either short or long evolutionary time scales, such as microsatellites or restriction site‐associated DNA sequencing (RAD‐seq) in the former case and conventional amplicon sequencing of organellar DNA in the latter. The potential of molecular ecology studies to address and resolve patterns and processes around the species level in radiating groups of taxa is currently limited primarily by sample size and a dearth of information on radiating nuclear genomes as opposed to organellar ones. Based on our literature survey and personal experience, we suggest possible ways forward in the coming years. We touch on the potential and current limitations of whole‐genome sequencing (WGS) in studies of radiations. We suggest that WGS and targeted (‘capture’) resequencing emerge as the methods of choice for scaling up the sampling of populations, species and genomes, including currently understudied organismal groups and the genes or regulatory elements expected to matter most to species radiations.     

火干扰对森林生态系统土壤呼吸组分的影响研究进展

土壤呼吸是陆地生态系统与大气碳交换的主要方式,主要分为自养呼吸和异养呼吸。土壤呼吸不仅是森林生态系统碳循环过程的关键环节,也是森林生态系统能量流动和物质循环的重要生态过程。火作为森林生态系统中一个重要的生态因子,可以在短时间内对土壤呼吸组分造成巨大的影响。火干扰对土壤呼吸组分的影响与火烧强度、火烧频率、火烧持续时间以及火后恢复等因子有关,通过影响植被的根系与组成、微生物群落数量与结构,凋落物的数量以及生态系统的环境和小气候等,进而对土壤呼吸产生影响。火干扰对土壤呼吸影响整体表现为火烧后土壤呼吸速率下降,在几个月至几年内恢复到火烧前水平,之后火继续对土壤呼吸产生影响长达数年至数十年。通过描述火烧强度、火烧频率以及火后恢复时间,阐述火干扰对土壤呼吸组分的直接影响,以及通过火后环境对土壤呼吸组分产生的间接影响,来揭示火干扰对森林生态系统土壤呼吸组分的影响。同时针对火干扰对土壤呼吸组分的影响进行以下3个方面的研究展望：（1）火后产生的黑碳对土壤呼吸组分的影响;（2）火后植被恢复对土壤呼吸组分产生的影响;（3）火后土壤呼吸组分的长期变化规律。     

Management of the natural ecosystems of the Cape Peninsula: current status and future prospects

The Cape Peninsula is an area of outstanding natural beauty and exceptional biodiversity, worthy of proclamation as a World Heritage Site. The area is dominated by fynbos vegetation, usually managed by means of prescribed burning, together with various programmes aimed at the control of invasive alien plant species. Effective management of the Peninsula is bedevilled by the fact that the area is controlled by no less than 14 different public bodies, resulting in fragmentation of effort and the lack of a standardized approach to management. Historically, many official and unofficial investigations have called for this problem to be resolved, without success. The lack of coherent, focused, and well funded fire and alien weed control management plans for the entire Peninsula is a serious deficiency. Despite this, considerable progress has been made towards the establishment of a database for the Peninsula, and the development of decision support systems that can utilize this database for rational management. Adoption of such a system would provide a powerful uniting tramework that would standardize and influence the management approaches adopted by the various controlling authorities.     

Bacterial zoonoses with natural focality: current trends in epidemic manifestation

Current trends in epidemic manifestation of some bacterial zoonoses with natural focality and their role in human infectious pathology have been reviewed and analyzed. Update information on the etiological agents of "emerging" and "re-emerging" infections--Astrakhan spotted fever, bartonellosis, ixodes tick-borne borrelioses, monocytic erhrlichiosis and canine brucellosis, recently isolated on the territory of Russia, is presented. The main factors at play in the process of urbanization of bacterial zoonoses are discussed.