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.     

Stability,purification, and applications of bromelain: A review

Bromelain is a cysteine protease found in pineapple tissue. Because of its anti‐inflammatory and anti‐cancer activities, as well as its ability to induce apoptotic cell death, bromelain has proved useful in several therapeutic areas. The market for this protease is growing, and several studies exploring various properties of this molecule have been reported. This review aims to compile this data, and summarize the main findings on bromelain in the literature to date. The physicochemical properties and stability of bromelain under different conditions are discussed. Several studies on the purification of bromelain from crude extracts using a wide range of techniques such as liquid–liquid extractions by aqueous two‐phase system, ultrafiltration, precipitation, and chromatography, have been reported. Finally, the various applications of bromelain are presented. This review therefore covers the main properties of bromelain, aiming to provide an up‐to‐date compilation of the data reported on this enzyme. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 32:5–13, 2016     

旧石器时代旷野遗址形成过程研究综述

遗址形成过程(或成因)研究是以地质考古学的研究手段为出发点,解读古人类遗址的形成和埋藏过程,其研究结果对正确解读遗址完整性和早期人类生存行为具有重要意义。该研究方向在中国尚未引起足够重视,这在一定程度上降低了我国古人类学和旧石器时代考古学学术研究的国际影响力。鉴于旷野遗址在保存早期人类化石及遗物方面的特殊地位,本文以地质考古学为出发点,系统分析有关旷野遗址形成过程研究所涉及的科学问题,对Glynn Isaac在东非创立的一套系统解读旷野遗址形成过程研究所涉及的指标进行梳理。此外,作者以古人类活动遗物的埋藏和空间分布特征为切入点,详细介绍目前从事旷野遗址成因研究所涉及的关键指标及学术意义,并对中国境内有关遗址成因研究以及旷野遗址形成过程研究的历史与现状进行讨论。     

Fire in the Riparian Zone: Characteristics and Ecological Consequences

We review the current understandings of the frequency, spatial distributions, mechanisms, and ecological consequences of fire in riparian zones. Riparian zones are well known for influencing many ecological processes at local to landscape scales, and fire can have an important ecosystem-scale influence on them. Riparian zones differ from surrounding uplands in their biophysical templates, moisture regimes and disturbance regimes; as a consequence the characteristics and effects of fire are different than in adjacent uplands. Fire impacts on riparian zones vary proportionally with the severity and extent of burning in the catchment and are affected by stream size. Riparian zones can act as a buffer against fire and therefore as a refuge for fire-sensitive species. However, under some circumstances, such as dry pre-fire climatic conditions and the accumulation of dry fuel, riparian areas become corridors for fire movement. Fire incursion into riparian zones creates canopy gaps and drier conditions, which allow subsequent build up of dead wood and establishment of fire adapted species. In concert, this increases fuel loads and the probability of another fire. Secondary effects of riparian fire include altering nutrient fluxes and cycling, increasing sediment loads, and stimulating erosion. We conclude that riparian fires are potentially important in shaping ecological characteristics in many regions, but this is poorly quantified. A better understanding of riparian fire regimes is essential to assess the effects of fire in helping shape the complex ecological characteristics of riparian zones over the longer-term.     

Cross–Scale Interactions and Changing Pattern–Process Relationships: Consequences for System Dynamics

Cross–scale interactions refer to processes at one spatial or temporal scale interacting with processes at another scale to result in nonlinear dynamics with thresholds. These interactions change the pattern–process relationships across scales such that fine-scale processes can influence a broad spatial extent or a long time period, or broad-scale drivers can interact with fine-scale processes to determine system dynamics. Cross–scale interactions are increasing recognized as having important influences on ecosystem processes, yet they pose formidable challenges for understanding and forecasting ecosystem dynamics. In this introduction to the special feature, “Cross–scale interactions and pattern–process relationships”, we provide a synthetic framework for understanding the causes and consequences of cross–scale interactions. Our framework focuses on the importance of transfer processes and spatial heterogeneity at intermediate scales in linking fine- and broad-scale patterns and processes. Transfer processes and spatial heterogeneity can either amplify or attenuate system response to broad-scale drivers. Providing a framework to explain cross–scale interactions is an important step in improving our understanding and ability to predict the impacts of propagating events and to ameliorate these impacts through proactive measures.     

Unusual alternations of floral organs in <Emphasis Type="Italic">Paeonia</Emphasis>: Structure and possible mechanism of formation

Morphological analysis of flowers was carried out in Paeonia L. cultivars. Some unusual alternations of floral organs were described: sepal-(petal-stamen) × n-carpel, where 2 ≤ n ≤ 4 (appearance of an additional zone of petal and stamen formation in the medial flower part). The identity of floral organs was not affected in the flowers with this unusual alternation. It was shown on the basis of mathematical simulation of the genes responsible for flower development that these alternations may be determined by increased pool of stem cells, which may lead to delayed termination of flower development.     

带有移民的两性分支过程极限性质

考虑带有移民的两性分支过程,这里移民数量依赖于当前人口总数,在下临界状态情形,本文证明了此过程收敛于一平衡分布．     

Phytoplankton food quality control of planktonic food web processes

We developed a mechanistic model of nutrient, phytoplankton, zooplankton and fish interactions to test the effects of phytoplankton food quality for herbivorous zooplankton on planktonic food web processes. When phytoplankton food quality is high strong trophic cascades suppress phytoplankton biomass, the zooplankton can withstand intense zooplanktivory, and energy is efficiently transferred through the food web sustaining higher trophic level production. Low food quality results in trophic decoupling at the plant-animal interface, with phytoplankton biomass determined primarily by nutrient availability, zooplankton easily eliminated by fish predation, and poor energy transfer through the food web. At a given nutrient availability, food quality and zooplanktivory interact to determine zooplankton biomass which in turn determines algal biomass. High food quality resulted in intense zooplankton grazing which favored fast-growing phytoplankton taxa, whereas fish predation favored slow-growing phytoplankton. These results suggest algal food quality for herbivorous zooplankton can strongly influence the nature of aquatic food web dynamics, and can have profound effects on water quality and fisheries production. Handling editor: D. Hamilton