The clinical course ofchronic liver diseases is significantly dependent on the progression rate and the extent offibrosis, i.e. the non-structured replacement of necrotic parenchyma by extracellular matrix. Fibrogenes...The clinical course ofchronic liver diseases is significantly dependent on the progression rate and the extent offibrosis, i.e. the non-structured replacement of necrotic parenchyma by extracellular matrix. Fibrogenesis, i.e. the development offibrosis can be regarded as an unlimited wound healing process, which is based on matrix (connective tissue) synthesis in activated hepatic stellate cells, fibroblasts (fibrocytes), hepatocytes and biliary epithelial cells, which are converted to matrix-producing (myo-)fibroblasts by a process defined as epithelial-mesenchymal transition. Blood (noninvasive) biomarkers offibrogenesis and fibrosis can be divided into class and class analytes. Class biomarkers are those single tests, which are based on the pathophysiology offibrosis, whereas class biomarkers aremostly multiparametric algorithms, which have been statistically evaluated with regard to the detection and activity ofongoing fibrosis. Currently available markers fulfil the criteria ofideal clinical-chemical tests only partially, but increased understanding ofthe complex pathogenesis offibrosis offers additional ways for pathophysiologically well based serum (plasma) biomarkers. They include TGF-β-driven marker proteins, bone marrow-derived cells (fibrocytes), and cytokines, which govern proand anti-fibrotic activities. Proteomic and glycomic approaches ofserum are under investigation to set up specific protein or carbohydrate profiles in patients with liver fibrosis. These and other novel parameters will supplement or eventually replaceliver biopsy/histology, high resolution imaging analysis, and elastography for the detection and monitoring of patients at risk ofdeveloping liver fibrosis.展开更多
The agricultural liberalization market process remains stalled Doha Round. The terms in protection levels reductions are negotiated, but the emergence of the global crisis constrains public resources to sustain them. ...The agricultural liberalization market process remains stalled Doha Round. The terms in protection levels reductions are negotiated, but the emergence of the global crisis constrains public resources to sustain them. In addition, the use of some grains as inputs in the production of biofuels, has contributed to the price increase in foods, although this production is an alternative to fossil fuels use and can help to reduce further environmental degradation. In this paper we analyze the main variables to be taken into account when negotiating the liberalization of agricultural trade, but also ofbiofuels in the context of Doha Round.展开更多
In recent decades, a growing worldwide trend of developing the biodegradable lubricants has been prevailing to form a specific field of green chemistry and green engineering. Enhancement of biodegradability of unreadi...In recent decades, a growing worldwide trend of developing the biodegradable lubricants has been prevailing to form a specific field of green chemistry and green engineering. Enhancement of biodegradability of unreadily biodegradable petroleum-based lubricants has as such become an urgent must. For over a decade the authors have been focusing on the improvement of biodegradability of unreadily biodegradable lubricants such as petroleum-based lubricating oils and greases. A new idea of lubricant biodegradation enhancer was put forward by the authors with the aim to stimulate the biodegradation of unreadily biodegradable lubricants by incorporating the enhancer into the lubricants in order to turn the lubricants into greener biodegradable ones and to help in situ bioremediation of lubricant-contaminated environment. This manuscript summarizes our recent efforts relating to the chemistry and technology of biodegradation enhancers for lubricants. Firstly, the chemistry of lubricant biodegradation enhancers was designed based on the principles of bioremediation for the treatment of hydrocarbon contaminated environment. Secondly, the ability of the designed biodegradation enhancers for increasing the biodegradability of unreadily biodegradable industrial lubricants was investigated through biodegradability evaluation tests, microbial population analysis, and biodegradation kinetics modeling. Finally, the impact of biodegradation enhancers on some crucial performance characteristics of lubricants such as lubricity and oxidation stability was tested via tribological evaluation and oxidation determinations. Our results have shown that the designed chemistry of nitrogenous and/or phosphorous compounds such as lauroyl glutamine, oleoyl glycine, oleic diethanolamide phosphate and lauric diethanolamide borate was outstanding in boosting biodegradation of petroleum-based lubricants which was ascribed to increase the microbial population and decrease the oil-water interfacial tension during the biodegradation process. Lubricants doped with the biodegradation enhancers exhibited much better biodegradability and higher biodegradation rate in the surrounding soils which could be well modeled by the exponential biodegradation kinetics. Furthermore, as lubricant dopants, the biodegradation enhancers also provided excellent capability in reducing friction and wear and in retarding oxidation of lubricants. In the nature of things, lubricant biodegradation enhancers, which are multi-functional not only in the improvement of biodegradability, but also in the fortification of lubricity and in the inhibition of oxidation of lubricants, are expected to be promising as a new category of lubricant additives.展开更多
Cell disruption focuses on obtaining a desired bioproduct within a cell, and it is the cell wall that must be disrupted to allow access to the contents of the cell. In animal cells, the plasma membrane is the only bar...Cell disruption focuses on obtaining a desired bioproduct within a cell, and it is the cell wall that must be disrupted to allow access to the contents of the cell. In animal cells, the plasma membrane is the only barrier separating cell contents from the environment. Sound waves from sonication, a mechanical technique for cell disintegration, have been used to disrupt as well as to aggregate cells as a step towards purification of a desired bioproduct. In the present study, an improved sonication process for the high yield of Newcastle disease virus (NDV) propagated in tissue culture was described. DF-I cell was cultured in 25cm^2 T flask. When cells were about 80% confluent, a lentogenic strain of NDV (F strain) was used to infect the cell monolayer. With evident cytopathic effect, cells were subjected to cycles of freeze-thaw before sonicating with varying combinations of amplitude, temperature and time. Cells were sonicated using a water bath Sonicator, Jac Ultrasonic 1505 JEIO TECH 4 KHz. From ANOVA analysis, a significant interaction between sonication time and amplitude was observed. This also corresponds to the highest F value observed.展开更多
It is hypothesized that steady anguilliform swimming motion of aquatic animals is purely reactive such that no net vortex wake is left downstream. This is versus carangiform and tunniform swimming of fish, where vorte...It is hypothesized that steady anguilliform swimming motion of aquatic animals is purely reactive such that no net vortex wake is left downstream. This is versus carangiform and tunniform swimming of fish, where vortex streams are shed from tail, fins, and body. But there the animal movements are such to produce partial vortex cancellation downstream in maximizing propulsive efficiency. In anguilliform swimming characteristic of the eel family, it is argued that the swimming motions are configured by the animal such that vortex shedding does not occur at all. However, the propulsive thrust in this case is higher order in the motion amplitude, so that relatively large coils are needed to produce relatively small thrust; the speeds of anguilliform swimmers are less than the carangiform and tunniforrn, which develop first order thrusts via lifting processes. Results of experimentation on live lamprey are compared to theoretical prediction which assumes the no-wake hypothesis. Two-dimensional analysis is first performed to set the concept. This is followed by three-dimensional analysis using slender-body theory. Slender-body theory has been applied by others in studying anguilliform swimming, as it is ideally suited to the geometry of the lamprey and other eel-like animals. The agreement between this new approach based on the hypothesis of wakeless swimming and the experiments is remarkably good in spite of the physical complexities.展开更多
Urbanization of China is substantial and growing, and water resources are crucial for both economic and social sustainable development. Unfortunately, the frequency and intensity of water contamination events are incr...Urbanization of China is substantial and growing, and water resources are crucial for both economic and social sustainable development. Unfortunately, the frequency and intensity of water contamination events are increasing at an unprecedented rate and often accompanied by increased pollutant loading due to human activities such as irreversible industrialization and urbanization. The impacts of human pollution are most evident and of greatest concern at the microbial level. The research of the Aquatic Ecohealth Group, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, has been focusing mainly on aquatic microorganisms in the urban environment, from drinking water and landscape water to waste water. Its projects fall into three categories: biomonitoring and bioassessment, microbial ecology and diversity, ecotoxicology and environmental microbiology. Its scientif ic topics include the aquatic ecological safety and microbial food web.展开更多
【目的】利用稳定同位素代谢标记(stable-isotope labeling by amino acids in cell culture,SILAC)技术完成心肌细胞内蛋白的完整标记,为研究心肌缺氧等高原性心肌损伤提供相对定量的标准。【方法】分别采用中度和重度SILAC培养基培养...【目的】利用稳定同位素代谢标记(stable-isotope labeling by amino acids in cell culture,SILAC)技术完成心肌细胞内蛋白的完整标记,为研究心肌缺氧等高原性心肌损伤提供相对定量的标准。【方法】分别采用中度和重度SILAC培养基培养心肌H9c2细胞,培养基中赖氨酸和精氨酸浓度分别为0.798和0.398 mmol/L;中度标记培养基含有赖氨酸4,4,5,5-D4-Lysine(Lys4)和精氨酸13C6-Arginine(Arg6);重度标记培养基含有赖氨酸13C615N2-Lysine(Lys8)和精氨酸13C615N4-Arginine(Arg10);通过连续培养6代后,提取细胞蛋白,采用过滤辅助蛋白组样本制备方法(Filter aided proteome preparation,FASP)联合12.5μg/ml质谱级胰蛋白酶溶液分别消化两种不同标记策略的细胞蛋白,经脱盐后进行高效液相结合质谱检测。所得数据由蛋白组学搜索软件MaxQuant进行分析,高斯拟合正态分布计算标记效率,GO分析鉴定蛋白参与的细胞生物学进程。【结果】中度SILAC标记组鉴定621个蛋白,正态分布μ值为5.06,标记效率为97.1%;重度SILAC标记组鉴定966个蛋白,正态分布μ值为5.98,标记效率为98.4%。这些蛋白主要集中于翻译、糖酵解等生物学进程。【结论】成功实现两种SILAC条件下心肌细胞H9c2蛋白的完整代谢标记,为研究高原性心肌损伤提供了蛋白组学的定量标准。展开更多
Deep-sea environment,characterized by high pressures,extremely high/low temperatures,limited photosynthesis-generated organic matter,darkness,and high levels of corrosion,is home to flourishing special ecosystems in t...Deep-sea environment,characterized by high pressures,extremely high/low temperatures,limited photosynthesis-generated organic matter,darkness,and high levels of corrosion,is home to flourishing special ecosystems in the world.Here,we illustrate how the deep-sea equipment offers insights into the study of life in the deep sea based on the work in the past five decades.We first describe how organisms in the deep sea are studied,even though it is highly difficult to get access to such extreme environments.We then explain the role of deep-sea technologies in advancing research on the evolution of organisms in hydrothermal vents,cold seeps,seamounts,oceanic trenches,and whale falls from the following perspectives:biological diversity,mechanisms of environmental adaptation,biological evolution,and ecosystem connectivity.Finally,to better understand the function and service of deep-sea organisms,and further conserve the special creatures under anthropologic activity and climate change,we highlight the importance of innovative deep-sea technologies to promote cutting-edge research on deep-sea organisms,and note the remaining challenges and developing directions for deep-sea equipment.展开更多
With high water content(~90 wt%) and significantly improved mechanical strength(~MPa),double network(DN) hydrogels have emerged as promising biomaterials with widespread applications in biomedicine.In recent years,D...With high water content(~90 wt%) and significantly improved mechanical strength(~MPa),double network(DN) hydrogels have emerged as promising biomaterials with widespread applications in biomedicine.In recent years,DN hydrogels with extremely high mechanical strength have achieved great advance,and scientists have designed a series of natural and biomimetic DN hydrogels with novel functions including low friction,low wear,mechanical anisotropy and cell compatibility.These advances have also led to new design of biocompatible DN hydrogels for regeneration of tissues such as cartilage.In this paper,we reviewed the strategies of designing high-strength DN hydrogel and analyzed the factors that affect DN hydrogel properties.We also discussed the challenges and future development of the DN hydrogel in view of its potential as biomaterials for their biomedical applications.展开更多
MacArthur and Wilson's equilibrium theory is one of the most influential theories in ecology.Although evolution on islands is to be important to island biodiversity,speciation has not been well integrated into isl...MacArthur and Wilson's equilibrium theory is one of the most influential theories in ecology.Although evolution on islands is to be important to island biodiversity,speciation has not been well integrated into island biogeography models.By incorporating speciation and factors influencing it into the MacArthur-Wilson model,we propose a generalized model unifying ecological and evolutionary processes and island features.Intra-island speciation may play an important role in both island species richness and endemism,and the contribution of speciation to local species diversity may eventually be greater than that of immigration under certain conditions.Those conditions are related to the per species speciation rate,per species extinction rate,and island features,and they are independent of immigration rate.The model predicts that large islands will have a high,though not the highest,proportional endemism when other parameters are fixed.Based on the generalized model,changes in species richness and endemism on an oceanic island over time were predicted to be similar to empirical observations.Our model provides an ideal starting point for re-evaluating the role of speciation and re-analyzing available data on island species diversity,especially those biased by the MacArthur-Wilson model.展开更多
Researchers hope that establishing a notion of proximity using topology will help to clarify the biological processes underlying the evolution of living organisms. The simple model presented here, using RNA shapes, ca...Researchers hope that establishing a notion of proximity using topology will help to clarify the biological processes underlying the evolution of living organisms. The simple model presented here, using RNA shapes, can carry over to more general and complex genotype-phenotype systems. Proximity is an important component of continuity, in both real-world and topological terms. Consequently, phenotype spaces provide an appropriate setting for modeling and investigating continuous and discontinuous evolutionary change.展开更多
The expanding scale and increasing rate of marine biological invasions have been documented since the early 20th century. Besides their global ecological and economic impacts, non-indigenous species (NIS) also have ...The expanding scale and increasing rate of marine biological invasions have been documented since the early 20th century. Besides their global ecological and economic impacts, non-indigenous species (NIS) also have attracted much attention as opportunities to explore important eco-evolutionary processes such as rapid adaptation, long-distance dispersal and range expansion, and secondary contacts between divergent evolutionary lineages. In this context, genetic tools have been extensively used in the past 20 years. Three important issues appear to have emerged from such studies. First, the study of NIS has revealed unexpected cryptic diversity in what had previously been assumed homogeneous entities. Second, there has been surprisingly little evidence of strong founder events accompanying marine introductions, a pattern possibly driven by large propagule loads. Third, the evolutionary processes leading to successful invasion have been difficult to ascertain due to faint genetic signals. Here we explore the potential of novel tools associated with high-throughput sequencing (HTS) to address these still pressing issues. Dramatic increase in the number of loci accessible via HTS has the potential to radically increase the power of analyses aimed at species delineation, exploring the population genomic consequences of range expansions, and examining evolutionary processes such as admixture, introgression, and adaptation. Nevertheless, the value of this new wealth of genomic data will ultimately depend on the ability to couple it with expanded "traditional" efforts, including exhaustive sampling of marine populations over large geographic scales, integrated taxonomic analyses, and population level exploration of quantitative trait differentiation through common-garden and other laboratory experiments.展开更多
基金The study was suporroted by the National Natural Science Foundation of China (No. 20775059), the Ministry of Education ot China (No. NCET-08-0464), and the Northwest A&F University.
文摘The clinical course ofchronic liver diseases is significantly dependent on the progression rate and the extent offibrosis, i.e. the non-structured replacement of necrotic parenchyma by extracellular matrix. Fibrogenesis, i.e. the development offibrosis can be regarded as an unlimited wound healing process, which is based on matrix (connective tissue) synthesis in activated hepatic stellate cells, fibroblasts (fibrocytes), hepatocytes and biliary epithelial cells, which are converted to matrix-producing (myo-)fibroblasts by a process defined as epithelial-mesenchymal transition. Blood (noninvasive) biomarkers offibrogenesis and fibrosis can be divided into class and class analytes. Class biomarkers are those single tests, which are based on the pathophysiology offibrosis, whereas class biomarkers aremostly multiparametric algorithms, which have been statistically evaluated with regard to the detection and activity ofongoing fibrosis. Currently available markers fulfil the criteria ofideal clinical-chemical tests only partially, but increased understanding ofthe complex pathogenesis offibrosis offers additional ways for pathophysiologically well based serum (plasma) biomarkers. They include TGF-β-driven marker proteins, bone marrow-derived cells (fibrocytes), and cytokines, which govern proand anti-fibrotic activities. Proteomic and glycomic approaches ofserum are under investigation to set up specific protein or carbohydrate profiles in patients with liver fibrosis. These and other novel parameters will supplement or eventually replaceliver biopsy/histology, high resolution imaging analysis, and elastography for the detection and monitoring of patients at risk ofdeveloping liver fibrosis.
文摘The agricultural liberalization market process remains stalled Doha Round. The terms in protection levels reductions are negotiated, but the emergence of the global crisis constrains public resources to sustain them. In addition, the use of some grains as inputs in the production of biofuels, has contributed to the price increase in foods, although this production is an alternative to fossil fuels use and can help to reduce further environmental degradation. In this paper we analyze the main variables to be taken into account when negotiating the liberalization of agricultural trade, but also ofbiofuels in the context of Doha Round.
基金the financial support provided by the National Natural Science Foundation of China (project Nos.50975282 and 50275147)the Natural Science Foundation of Chongqing, China (project No. CSTC 2008BA4037)
文摘In recent decades, a growing worldwide trend of developing the biodegradable lubricants has been prevailing to form a specific field of green chemistry and green engineering. Enhancement of biodegradability of unreadily biodegradable petroleum-based lubricants has as such become an urgent must. For over a decade the authors have been focusing on the improvement of biodegradability of unreadily biodegradable lubricants such as petroleum-based lubricating oils and greases. A new idea of lubricant biodegradation enhancer was put forward by the authors with the aim to stimulate the biodegradation of unreadily biodegradable lubricants by incorporating the enhancer into the lubricants in order to turn the lubricants into greener biodegradable ones and to help in situ bioremediation of lubricant-contaminated environment. This manuscript summarizes our recent efforts relating to the chemistry and technology of biodegradation enhancers for lubricants. Firstly, the chemistry of lubricant biodegradation enhancers was designed based on the principles of bioremediation for the treatment of hydrocarbon contaminated environment. Secondly, the ability of the designed biodegradation enhancers for increasing the biodegradability of unreadily biodegradable industrial lubricants was investigated through biodegradability evaluation tests, microbial population analysis, and biodegradation kinetics modeling. Finally, the impact of biodegradation enhancers on some crucial performance characteristics of lubricants such as lubricity and oxidation stability was tested via tribological evaluation and oxidation determinations. Our results have shown that the designed chemistry of nitrogenous and/or phosphorous compounds such as lauroyl glutamine, oleoyl glycine, oleic diethanolamide phosphate and lauric diethanolamide borate was outstanding in boosting biodegradation of petroleum-based lubricants which was ascribed to increase the microbial population and decrease the oil-water interfacial tension during the biodegradation process. Lubricants doped with the biodegradation enhancers exhibited much better biodegradability and higher biodegradation rate in the surrounding soils which could be well modeled by the exponential biodegradation kinetics. Furthermore, as lubricant dopants, the biodegradation enhancers also provided excellent capability in reducing friction and wear and in retarding oxidation of lubricants. In the nature of things, lubricant biodegradation enhancers, which are multi-functional not only in the improvement of biodegradability, but also in the fortification of lubricity and in the inhibition of oxidation of lubricants, are expected to be promising as a new category of lubricant additives.
文摘Cell disruption focuses on obtaining a desired bioproduct within a cell, and it is the cell wall that must be disrupted to allow access to the contents of the cell. In animal cells, the plasma membrane is the only barrier separating cell contents from the environment. Sound waves from sonication, a mechanical technique for cell disintegration, have been used to disrupt as well as to aggregate cells as a step towards purification of a desired bioproduct. In the present study, an improved sonication process for the high yield of Newcastle disease virus (NDV) propagated in tissue culture was described. DF-I cell was cultured in 25cm^2 T flask. When cells were about 80% confluent, a lentogenic strain of NDV (F strain) was used to infect the cell monolayer. With evident cytopathic effect, cells were subjected to cycles of freeze-thaw before sonicating with varying combinations of amplitude, temperature and time. Cells were sonicated using a water bath Sonicator, Jac Ultrasonic 1505 JEIO TECH 4 KHz. From ANOVA analysis, a significant interaction between sonication time and amplitude was observed. This also corresponds to the highest F value observed.
文摘It is hypothesized that steady anguilliform swimming motion of aquatic animals is purely reactive such that no net vortex wake is left downstream. This is versus carangiform and tunniform swimming of fish, where vortex streams are shed from tail, fins, and body. But there the animal movements are such to produce partial vortex cancellation downstream in maximizing propulsive efficiency. In anguilliform swimming characteristic of the eel family, it is argued that the swimming motions are configured by the animal such that vortex shedding does not occur at all. However, the propulsive thrust in this case is higher order in the motion amplitude, so that relatively large coils are needed to produce relatively small thrust; the speeds of anguilliform swimmers are less than the carangiform and tunniforrn, which develop first order thrusts via lifting processes. Results of experimentation on live lamprey are compared to theoretical prediction which assumes the no-wake hypothesis. Two-dimensional analysis is first performed to set the concept. This is followed by three-dimensional analysis using slender-body theory. Slender-body theory has been applied by others in studying anguilliform swimming, as it is ideally suited to the geometry of the lamprey and other eel-like animals. The agreement between this new approach based on the hypothesis of wakeless swimming and the experiments is remarkably good in spite of the physical complexities.
文摘Urbanization of China is substantial and growing, and water resources are crucial for both economic and social sustainable development. Unfortunately, the frequency and intensity of water contamination events are increasing at an unprecedented rate and often accompanied by increased pollutant loading due to human activities such as irreversible industrialization and urbanization. The impacts of human pollution are most evident and of greatest concern at the microbial level. The research of the Aquatic Ecohealth Group, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, has been focusing mainly on aquatic microorganisms in the urban environment, from drinking water and landscape water to waste water. Its projects fall into three categories: biomonitoring and bioassessment, microbial ecology and diversity, ecotoxicology and environmental microbiology. Its scientif ic topics include the aquatic ecological safety and microbial food web.
基金supported by the National Natural Science Foundation of China(42022046)the National Key Research and Development Program(2021YFF0502300)+1 种基金the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0401 and GML2019ZD0403)Guangdong Natural Resources Foundation(GDNRC[2022]45)。
文摘Deep-sea environment,characterized by high pressures,extremely high/low temperatures,limited photosynthesis-generated organic matter,darkness,and high levels of corrosion,is home to flourishing special ecosystems in the world.Here,we illustrate how the deep-sea equipment offers insights into the study of life in the deep sea based on the work in the past five decades.We first describe how organisms in the deep sea are studied,even though it is highly difficult to get access to such extreme environments.We then explain the role of deep-sea technologies in advancing research on the evolution of organisms in hydrothermal vents,cold seeps,seamounts,oceanic trenches,and whale falls from the following perspectives:biological diversity,mechanisms of environmental adaptation,biological evolution,and ecosystem connectivity.Finally,to better understand the function and service of deep-sea organisms,and further conserve the special creatures under anthropologic activity and climate change,we highlight the importance of innovative deep-sea technologies to promote cutting-edge research on deep-sea organisms,and note the remaining challenges and developing directions for deep-sea equipment.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51073127,51173144 )the Higher School Specialized Research Fund for the Doctoral Program FundingIssue (Grant No. 20100201110040 )+1 种基金the Operation Expenses for Universities’ Basic Scientific Research of Central Authorities (Grant No. 0109-08140018 )the New Research Support Project (Grant No. 08141001) from Xi’an Jiaotong University,P. R. China
文摘With high water content(~90 wt%) and significantly improved mechanical strength(~MPa),double network(DN) hydrogels have emerged as promising biomaterials with widespread applications in biomedicine.In recent years,DN hydrogels with extremely high mechanical strength have achieved great advance,and scientists have designed a series of natural and biomimetic DN hydrogels with novel functions including low friction,low wear,mechanical anisotropy and cell compatibility.These advances have also led to new design of biocompatible DN hydrogels for regeneration of tissues such as cartilage.In this paper,we reviewed the strategies of designing high-strength DN hydrogel and analyzed the factors that affect DN hydrogel properties.We also discussed the challenges and future development of the DN hydrogel in view of its potential as biomaterials for their biomedical applications.
基金supported by the National Natural Science Foundation of China (Grant No. 30870361)the National High Technology Research and Development Program of China (Grant No. 2007AA09Z432)the "211 Project" of East China Normal University
文摘MacArthur and Wilson's equilibrium theory is one of the most influential theories in ecology.Although evolution on islands is to be important to island biodiversity,speciation has not been well integrated into island biogeography models.By incorporating speciation and factors influencing it into the MacArthur-Wilson model,we propose a generalized model unifying ecological and evolutionary processes and island features.Intra-island speciation may play an important role in both island species richness and endemism,and the contribution of speciation to local species diversity may eventually be greater than that of immigration under certain conditions.Those conditions are related to the per species speciation rate,per species extinction rate,and island features,and they are independent of immigration rate.The model predicts that large islands will have a high,though not the highest,proportional endemism when other parameters are fixed.Based on the generalized model,changes in species richness and endemism on an oceanic island over time were predicted to be similar to empirical observations.Our model provides an ideal starting point for re-evaluating the role of speciation and re-analyzing available data on island species diversity,especially those biased by the MacArthur-Wilson model.
文摘Researchers hope that establishing a notion of proximity using topology will help to clarify the biological processes underlying the evolution of living organisms. The simple model presented here, using RNA shapes, can carry over to more general and complex genotype-phenotype systems. Proximity is an important component of continuity, in both real-world and topological terms. Consequently, phenotype spaces provide an appropriate setting for modeling and investigating continuous and discontinuous evolutionary change.
文摘The expanding scale and increasing rate of marine biological invasions have been documented since the early 20th century. Besides their global ecological and economic impacts, non-indigenous species (NIS) also have attracted much attention as opportunities to explore important eco-evolutionary processes such as rapid adaptation, long-distance dispersal and range expansion, and secondary contacts between divergent evolutionary lineages. In this context, genetic tools have been extensively used in the past 20 years. Three important issues appear to have emerged from such studies. First, the study of NIS has revealed unexpected cryptic diversity in what had previously been assumed homogeneous entities. Second, there has been surprisingly little evidence of strong founder events accompanying marine introductions, a pattern possibly driven by large propagule loads. Third, the evolutionary processes leading to successful invasion have been difficult to ascertain due to faint genetic signals. Here we explore the potential of novel tools associated with high-throughput sequencing (HTS) to address these still pressing issues. Dramatic increase in the number of loci accessible via HTS has the potential to radically increase the power of analyses aimed at species delineation, exploring the population genomic consequences of range expansions, and examining evolutionary processes such as admixture, introgression, and adaptation. Nevertheless, the value of this new wealth of genomic data will ultimately depend on the ability to couple it with expanded "traditional" efforts, including exhaustive sampling of marine populations over large geographic scales, integrated taxonomic analyses, and population level exploration of quantitative trait differentiation through common-garden and other laboratory experiments.