Mitochondria play a key role in lipid metabolism,and mitochondrial DNA(mtDNA)mutations are thus considered to affect obesity susceptibility by altering oxidative phosphorylation and mitochondrial function.In this stud...Mitochondria play a key role in lipid metabolism,and mitochondrial DNA(mtDNA)mutations are thus considered to affect obesity susceptibility by altering oxidative phosphorylation and mitochondrial function.In this study,we investigate mtDNA variants that may affect obesity risk in 2877 Han Chinese individuals from 3 independent populations.The association analysis of 16 basal mtDNA haplogroups with body mass index,waist circumference,and waist-to-hip ratio reveals that only haplogroup M7 is significantly negatively correlated with all three adiposity-related anthropometric traits in the overall cohort,verified by the analysis of a single population,i.e.,the Zhengzhou population.Furthermore,subhaplogroup analysis suggests that M7b1a1 is the most likely haplogroup associated with a decreased obesity risk,and the variation T12811C(causing Y159H in ND5)harbored in M7b1a1 may be the most likely candidate for altering the mitochondrial function.Specifically,we find that proportionally more nonsynonymous mutations accumulate in M7b1a1 carriers,indicating that M7b1a1 is either under positive selection or subject to a relaxation of selective constraints.We also find that nuclear variants,especially in DACT2 and PIEZO1,may functionally interact with M7b1a1.展开更多
Darwin’s theory of evolution believes that biological evolution is a process of natural selection. This theory has been supported by much evidence, but the internal biological mechanism is not clear. Here, I elaborat...Darwin’s theory of evolution believes that biological evolution is a process of natural selection. This theory has been supported by much evidence, but the internal biological mechanism is not clear. Here, I elaborate on the cycle of potassium resources on the earth and the biological utilization and efficiency, which may be the core mechanism of natural selection and affect the evolution of organisms and the development of human society.展开更多
In the field of anthropology, the uniparerttally inherited Y chromosome has long been used to trace the paternal lineage of the populations and to understand differences in migration and population genetics between ma...In the field of anthropology, the uniparerttally inherited Y chromosome has long been used to trace the paternal lineage of the populations and to understand differences in migration and population genetics between males and females, with additional advantages of small effective population size, suf- ficient markers, and population-specific haplotype distribution （Jobling and Tyler-Smith, 1995; Jin and Su, 2000; Underhill et al., 2000）. Many such population studies have rested on the assumption that all the Y chromosome markers in the non- recombination regions are selectively neutral （Jobling and Tyler-Smith, 2003）.展开更多
Evolutionary experiments provide a unique lens through which to observe the impacts of natural selection on crop evolution,domestication,and adaptation through empirical evidence.Enabled by modern technologies—such a...Evolutionary experiments provide a unique lens through which to observe the impacts of natural selection on crop evolution,domestication,and adaptation through empirical evidence.Enabled by modern technologies—such as the development of large-scale,structured evolving populations,high-throughput phenotyping,and genomics-driven genetics studies—the transition from theoretical evolutionary biology to practical application is now possible for staple crops.The century-long Barley Composite Cross II(CCII)competition experiment has offered invaluable insights into understanding the genomic and phenotypic basis of natural and artificial selection driven by environmental adaptation during crop evolution and domestication.These experiments enable scientists to measure evolutionary dynamics,in real time,of genetic diversity,adaptation of fitness-associated traits,and the trade-offs inherent in selective processes.Beyond advancing our understanding of evolutionary biology and agricultural practices,these studies provide critical insights into addressing global challenges,from ensuring food security to fostering resilience in human societies.展开更多
Cereal genes are classified into two distinct classes according to the guanine-cytosine （GC） content at the third codon sites （GC3）. Natural selection and mutation bias have been proposed to affect the GC content....Cereal genes are classified into two distinct classes according to the guanine-cytosine （GC） content at the third codon sites （GC3）. Natural selection and mutation bias have been proposed to affect the GC content. However, there has been controversy about the cause of GC variation. Here, we characterized the GC content of 1 092 paralogs and other single-copy genes in the duplicated chromosomal regions of the rice genome （ssp. indica） and classified the paralogs into GC3-rich and GC3-poor groups. By referring to out-group sequences from Arabidopsis and maize, we confirmed that the average synonymous substitution rate of the GC3-rich genes is significantly lower than that of the GC3-poor genes. Furthermore, we explored the other possible factors corresponding to the GC variation including the length of coding sequences, the number of exons in each gene, the number of genes in each family, the location of genes on chromosomes and the protein functions. Consequently, we propose that natural selection rather than mutation bias was the primary cause of the GC variation.展开更多
Aims Floral traits in animal-pollinated plants are proposed to be selected by the behavior of pollinators,which create differential fitness.However,fitness estimation is not trivial and there is no agreed or universal...Aims Floral traits in animal-pollinated plants are proposed to be selected by the behavior of pollinators,which create differential fitness.However,fitness estimation is not trivial and there is no agreed or universal measure of fitness.in plants,fitness can be measured in various ways,including the number of fruits or seeds,probability of survival,or growth rate.Methods Because each fitness measure can be associated with different pol-linator behavior,estimating pollinator-mediated selection on floral traits can differ among various fitness measures.We used the annual Mediterranean plant,Linum pubescens,as a model to assess the relative role of various fitness measures in estimating pollinator-mediated selection on floral traits.We compared four maternal fit-ness measures and estimated their relative advantage in assessing natural selection on floral traits of L.pubescens.To identify whether each trait is under pollinator-mediated selection,we used media-tional analysis.Important Findings We found that each floral trait was under natural selection assessed by a different fitness measure.The color combination of floral tube throat and stamen color was under selection when using seed mass as a fitness measure,and floral diameter was under positive direc-tional selection when the number of seeds or number of fruits was used as a fitness measure.Selection on floral color was not mediated by pollinators’visitation rates,while flower diameter showed par-tial pollinator-mediated selection.We conclude that using several fitness measures gives an insight into the mechanisms underlying phenotypic selection on a floral trait,and facilitates the understand-ing of pollinator-mediated selection.展开更多
In this paper, we analyze variation in spectral reflectance and color pattern among populations to demonstrate dra-matic divergence between four distinct morphs of the mimic poison frog Ranitomeya imitator. We also an...In this paper, we analyze variation in spectral reflectance and color pattern among populations to demonstrate dra-matic divergence between four distinct morphs of the mimic poison frog Ranitomeya imitator. We also analyze genetic diver-gence in d-loop mtDNA sequences between populations. We then use coalescent-based simulations to demonstrate that the high levels of observed phenotypic divergence are not consistent with levels of genetic divergence expected under neutral drift among populations, implying an important role for selection in driving divergence between these populations .展开更多
Jack London is one of the most outstanding naturalistic writers in America who composed many renowned full-length novels.Jack London’s short story,"To Build a Fire"is a good reflection of naturalistic tende...Jack London is one of the most outstanding naturalistic writers in America who composed many renowned full-length novels.Jack London’s short story,"To Build a Fire"is a good reflection of naturalistic tendencies.It chooses"To Build a Fire"so as to fully understand his perspective of naturalism.First,it provides a brief introduction to Jack London and this short story.Second,it specifically displays naturalism in this short story from four aspects.Among them,objective authenticity is the most distinctive feature in naturalistic elements.Meanwhile,his literature creation is also deeply influenced by Darwin’s theory of evolution.It aims to investigate gold seeker’s failure that reflects natural selection and theory of survival of the fittest.Finally,it concludes that only by respecting nature can human beings survive in natural selection.Through the analysis of gold seeker’s tragic fate,it warns that the readers should master wild survival skills and live in harmony with nature.展开更多
This paper presents the development process relating to the conceptual design of glass/renewable natural fibrereinforced polymer hybrid composite motorcycle side cover.Motorcycle side cover is a component frequently m...This paper presents the development process relating to the conceptual design of glass/renewable natural fibrereinforced polymer hybrid composite motorcycle side cover.Motorcycle side cover is a component frequently made from plastic or steel that functions on covering the motorcycle parts,components and systems such as frame,battery,electrical systems and mechanical systems.Function Analysis Systems Techniques(FAST)is used to identify the functions of motorcycle side cover.The right-side cover of motorcycle model SYM E-Bonus 110 has been physically studied to identify the competitive benchmarking criteria.The functions and competitive benchmarking criteria are then compiled and integrated with the environmental requirements to identify the Product Design Specifications(PDS).The coir fibre has been selected from six identified dominant renewable natural fibre used for automotive component through integration of Ranking Method and Quality Based Selection(QBS).Then the polypropylene matrix is selected after shortlisting the existing thermoplastic that is used with coir fibre and has high suitability for injection moulding manufacturing.The polypropylene matrix is then evaluated using Weighted Evaluation Matrix(WEM)by comparing to benchmark material which is Acrylonitrile Butadiene Styrene(ABS).After that,the conceptual design development of glass/renewable coir fibre-reinforced polypropylene motorcycle side cover is carried out using an integrated Theory of Inventive Problem Solving(TRIZ)and Morphological Chart,followed by final conceptual design selection using integration of Pugh Scoring Method and QBS.The conceptual design development intended on improving the biodegradability to reduce pollution to the environment.However,the usage of glass/coir fibre-reinforced polypropylene hybrid composite may increase the weight due to higher density.Four innovative design concepts have been developed and the selected final concept design has the most minimum number of ribs and minimum thickness with the same ratio of glass fibre and natural fibre composition.展开更多
1 Technology of natural materials Early man used conveniently shaped stones as tools. ＂Workshop＂ areas have been found with large numbers of stones, some showing signs of being worked. However, organic materials li...1 Technology of natural materials Early man used conveniently shaped stones as tools. ＂Workshop＂ areas have been found with large numbers of stones, some showing signs of being worked. However, organic materials like wood will decay under normal wet conditions in the presence of oxygen, so we won＇t find the same sort of evidence for wooden tools. It is safe to assume that early man used sticks as probes and clubs, and maybe even for making some sort of nestlike protection against the elements and predators, since we see chimpanzees and other animals doing this sort of thing. So wood, and ahnost certainly other plant materials such as fibrous leaves, and bone and other materials gleaned from dead animals, would be used from the earliest times. We need to know this in order to establish the idea that Man can be expected to have a long history of the use and manipulation of natural materials. This needs skills in choosing materials for certain uses on the basis of their mechanical properties, whether those properties are to do with the ease of shaping the material or the effectiveness of that material in use. Occasionally the material was chosen simply because it was readily available. If we find that a particular material was always used for a certain job, it＇s reasonable to deduce that Man was exerting materials selection criteria through experience.展开更多
Sexual dichromatism represents a major form of phenotypic differentiation between the sexes in birds,and its evolution is likely shaped by the interplay between sexual and natural selection.The genus Ficedula,widely d...Sexual dichromatism represents a major form of phenotypic differentiation between the sexes in birds,and its evolution is likely shaped by the interplay between sexual and natural selection.The genus Ficedula,widely distributed across Eurasia,exhibits pronounced interspecific variation in both sexual dichromatism and migratory behavior,making it an ideal study system for investigating the evolutionary patterns and drivers of avian sexual dichromatism.In this study,we conducted a phylogenetic comparative analysis of plumage complexity and sexual dichromatism across 32 Ficedula species.We further explored how life-history traits influence the evolution of sexual dichromatism.Our results reveal a strong positive correlation between male plumage complexity and the degree of sexual dichromatism,with males evolving plumage complexity at significantly faster rates than females.Migratory species exhibit significantly higher levels of dichromatism.Furthermore,compared to monochromatic species,sexually dichromatic species are characterized by higher latitudinal occurrence,broader geographic distributions,and greater flight capacity.These findings demonstrated how sexual and natural selection jointly drive evolution of sexual dichromatism in Ficedula within phylogenetic constraints,advancing our understanding of the evolutionary drivers of avian sexual dichromatism.展开更多
Evolution,adaptation and selection always exist in the evolutionary process of any species,which is the result of interrelation and interaction between living things and their environments,and the incarnation of natur...Evolution,adaptation and selection always exist in the evolutionary process of any species,which is the result of interrelation and interaction between living things and their environments,and the incarnation of natural laws in the evolutionary process of any species. Only if accurately understanding their connotation and interrelation among them,taking the evolution of living things as the line with centralizing the human sustainable development,dialectically unifying the active adaptation of the human being to their environments and oriented selection of nature and the society to species,we can acquire a better understanding of evolution of living things and a deeper understanding of the human sustainable development under biologically evolutionary background and uphold the true Darwinism,modern evolutionary point of view and the concept of current sustainable development in theory and in practice.展开更多
Synonymous codon usage pattern presumably reflects gene expression optimization as a result of molecular evolution. Though much attention has been paid to various model organisms ranging from prokaryotes to eukaryotes...Synonymous codon usage pattern presumably reflects gene expression optimization as a result of molecular evolution. Though much attention has been paid to various model organisms ranging from prokaryotes to eukaryotes, codon usage has yet been extensively investigated for model legume Medicago truncatula. In present study, 39 531 available coding sequences （CDSs） from M. truncatula were examined for codon usage bias （CUB）. Based on analyses including neutrality plots, effective number of codons plots, and correlations between optimal codons frequency and codon adaptation index, we conclude that natural selection is a major driving force in M. truncatula CUB. We have identified 30 optimal codons encoding 18 amino acids based on relative synonymous codon usage. These optimal codons characteristically end with A or T, except for AGG and TTG encoding arginine and leucine respectively. Optimal codon usage is positively correlated with the GC content at three nucleotide positions of codons and the GC content of CDSs. The abundance of expressed sequence tag is a proxy for gene expression intensity in the legume, but has no relatedness with either CDS length or GC content. Collectively, we unravel the synonymous codon usage pattern in M. truncatula, which may serve as the valuable information on genetic engineering of the model legume and forage crop.展开更多
In the past decade there has been a profusion of studies highlighting covariation between individual differences in stress physiology and behavioural profiles, here called personalities. Such individual differences in...In the past decade there has been a profusion of studies highlighting covariation between individual differences in stress physiology and behavioural profiles, here called personalities. Such individual differences in ways of coping with stress are relevant both in biomedicine, since different personalities may experience a different stress and disease vulnerability, and in behavioural ecology, since their adaptive value and evolutionary maintenance are the subject of debate. However, the precise way in which individual stress differences and personalities are linked is unclear. Here we provide an updated overview of this covariation across different species and taxa, consider its functional significance and present working hypotheses for how behavioural and physiological responses to stress might be causally linked, affecting life-history traits such as dispersal and life-span [Current Zoology 56 （6）： 728-740, 2010].展开更多
The role of female sex pheromones in natural selection, particularly as a means for species recognition to avoid the generation of hybrid offspring with low fitness, has been widely explored and is generally accepted ...The role of female sex pheromones in natural selection, particularly as a means for species recognition to avoid the generation of hybrid offspring with low fitness, has been widely explored and is generally accepted by scholars. However, the significance of sex pheromones in shaping mate choice （sexual selection） and in competition over breeding resources （social se- lection） has been largely ignored. The effect of sexual selection on sex pheromones as a sexually dimorphic signaling trait has been discounted because the amount of pheromone released by females is typically minute, while the role of sex pheromones in competition over breeding resources （other than mates） has not yet been considered. As a result of natural selection, variation in sex pheromones among females is expected to be low, and males are not expected to choose their mates among phero- mone-releasing conspecific females. Sexual selection, on the other hand, should drive the increase in pheromone variance among females, and males are expected to choose females based on this variation. Moreover, social selection resulting from more general social interactions, for example competition among females for breeding sites and food, should also promote variance among female sex pheromones. Here, we review the cttrrent evidence for each of the three selection processes acting on sex pheromones of female moths as an advertising trait. We suggest that the three selection types are not mutually exclusive but rather act together to promote different fimess components in diverse ecological situations展开更多
After more than one hundred fifty years of the publication of On the Origin of Species by Darwin, scientists are still arguing on the relative importance of mutation and natural selection, on the driving force of orga...After more than one hundred fifty years of the publication of On the Origin of Species by Darwin, scientists are still arguing on the relative importance of mutation and natural selection, on the driving force of organismal evolution, on microevo- lution and macroevolution, etc. Such periodically repeated debates appeared to have introduced more chaos than musings. What happened and why？ Have we really considered our views, opinions and arguments under the big picture of evolution before pos- ing the questions？ Or are we talking past each other？ We do need some reflections. While we believe that the current evolutionary theory is doing fine, perhaps a refinement or re-encapsulation of its knowledge framework can help promote a better understanding of the evolutionary science as a whole and blow offthe mist over the big picture [Current Zoology 61 （1）： 217-220, 2015 ].展开更多
基金supported by the National Natural Science Foundation of China(32270670,32288101,32271186,and 32200482)the National Basic Research Program of China(2015FY111700)the CAMS Innovation Fund for Medical Sciences(2019-I2M-5-066).
文摘Mitochondria play a key role in lipid metabolism,and mitochondrial DNA(mtDNA)mutations are thus considered to affect obesity susceptibility by altering oxidative phosphorylation and mitochondrial function.In this study,we investigate mtDNA variants that may affect obesity risk in 2877 Han Chinese individuals from 3 independent populations.The association analysis of 16 basal mtDNA haplogroups with body mass index,waist circumference,and waist-to-hip ratio reveals that only haplogroup M7 is significantly negatively correlated with all three adiposity-related anthropometric traits in the overall cohort,verified by the analysis of a single population,i.e.,the Zhengzhou population.Furthermore,subhaplogroup analysis suggests that M7b1a1 is the most likely haplogroup associated with a decreased obesity risk,and the variation T12811C(causing Y159H in ND5)harbored in M7b1a1 may be the most likely candidate for altering the mitochondrial function.Specifically,we find that proportionally more nonsynonymous mutations accumulate in M7b1a1 carriers,indicating that M7b1a1 is either under positive selection or subject to a relaxation of selective constraints.We also find that nuclear variants,especially in DACT2 and PIEZO1,may functionally interact with M7b1a1.
文摘Darwin’s theory of evolution believes that biological evolution is a process of natural selection. This theory has been supported by much evidence, but the internal biological mechanism is not clear. Here, I elaborate on the cycle of potassium resources on the earth and the biological utilization and efficiency, which may be the core mechanism of natural selection and affect the evolution of organisms and the development of human society.
基金supported by the National Excellent Youth Science Foundation of China (No. 31222030)the National Natural Science Foundation of China (Nos. 31071098 and 91131002)+2 种基金the Shanghai Rising-Star Program (No. 12QA1400300)the Shanghai Commission of Education Research Innovation Key Project (No. 11zz04)the Shanghai Professional Development Funding (No. 2010001)
文摘In the field of anthropology, the uniparerttally inherited Y chromosome has long been used to trace the paternal lineage of the populations and to understand differences in migration and population genetics between males and females, with additional advantages of small effective population size, suf- ficient markers, and population-specific haplotype distribution （Jobling and Tyler-Smith, 1995; Jin and Su, 2000; Underhill et al., 2000）. Many such population studies have rested on the assumption that all the Y chromosome markers in the non- recombination regions are selectively neutral （Jobling and Tyler-Smith, 2003）.
基金supported by the National Key Research and Development Program of China(2023YFF1000100)the National Key R&D Program of China(grant number 2023YFA0914600)to SFC.
文摘Evolutionary experiments provide a unique lens through which to observe the impacts of natural selection on crop evolution,domestication,and adaptation through empirical evidence.Enabled by modern technologies—such as the development of large-scale,structured evolving populations,high-throughput phenotyping,and genomics-driven genetics studies—the transition from theoretical evolutionary biology to practical application is now possible for staple crops.The century-long Barley Composite Cross II(CCII)competition experiment has offered invaluable insights into understanding the genomic and phenotypic basis of natural and artificial selection driven by environmental adaptation during crop evolution and domestication.These experiments enable scientists to measure evolutionary dynamics,in real time,of genetic diversity,adaptation of fitness-associated traits,and the trade-offs inherent in selective processes.Beyond advancing our understanding of evolutionary biology and agricultural practices,these studies provide critical insights into addressing global challenges,from ensuring food security to fostering resilience in human societies.
基金the State Key Basic Research and Development Plan of China(2003CB715900)the National Natural Science Foundation of China(90408015,30121003 and 30430030).
文摘Cereal genes are classified into two distinct classes according to the guanine-cytosine （GC） content at the third codon sites （GC3）. Natural selection and mutation bias have been proposed to affect the GC content. However, there has been controversy about the cause of GC variation. Here, we characterized the GC content of 1 092 paralogs and other single-copy genes in the duplicated chromosomal regions of the rice genome （ssp. indica） and classified the paralogs into GC3-rich and GC3-poor groups. By referring to out-group sequences from Arabidopsis and maize, we confirmed that the average synonymous substitution rate of the GC3-rich genes is significantly lower than that of the GC3-poor genes. Furthermore, we explored the other possible factors corresponding to the GC variation including the length of coding sequences, the number of exons in each gene, the number of genes in each family, the location of genes on chromosomes and the protein functions. Consequently, we propose that natural selection rather than mutation bias was the primary cause of the GC variation.
文摘Aims Floral traits in animal-pollinated plants are proposed to be selected by the behavior of pollinators,which create differential fitness.However,fitness estimation is not trivial and there is no agreed or universal measure of fitness.in plants,fitness can be measured in various ways,including the number of fruits or seeds,probability of survival,or growth rate.Methods Because each fitness measure can be associated with different pol-linator behavior,estimating pollinator-mediated selection on floral traits can differ among various fitness measures.We used the annual Mediterranean plant,Linum pubescens,as a model to assess the relative role of various fitness measures in estimating pollinator-mediated selection on floral traits.We compared four maternal fit-ness measures and estimated their relative advantage in assessing natural selection on floral traits of L.pubescens.To identify whether each trait is under pollinator-mediated selection,we used media-tional analysis.Important Findings We found that each floral trait was under natural selection assessed by a different fitness measure.The color combination of floral tube throat and stamen color was under selection when using seed mass as a fitness measure,and floral diameter was under positive direc-tional selection when the number of seeds or number of fruits was used as a fitness measure.Selection on floral color was not mediated by pollinators’visitation rates,while flower diameter showed par-tial pollinator-mediated selection.We conclude that using several fitness measures gives an insight into the mechanisms underlying phenotypic selection on a floral trait,and facilitates the understand-ing of pollinator-mediated selection.
基金We are grateful to C. Aguilar, J. Cor-dova, and K. Siu Ting for their help at the Museo de Historia Natural, San Marcos, Peru, and K. Ramirez for help at the Ministry of Natural Resources. We thank E. Twomey for ad- vice and discussion. This research was funded by grants from the National Science Foundation （IOB-0544010）, the National Geographic Society （7658-04）, and an East Carolina Univer-sity Research and Development Grant （2006）. Research per-mits were obtained from the Ministry of Natural Resources （DGFFS） in Lima, Peru （Authorizations No. 050-2006-INRENA-IFFS-DCB, No. 067-2007-INRENA-IFFS-DCB, No. 005-2008-INRENA-IFFS-DCB, CITES 11076）.
文摘In this paper, we analyze variation in spectral reflectance and color pattern among populations to demonstrate dra-matic divergence between four distinct morphs of the mimic poison frog Ranitomeya imitator. We also analyze genetic diver-gence in d-loop mtDNA sequences between populations. We then use coalescent-based simulations to demonstrate that the high levels of observed phenotypic divergence are not consistent with levels of genetic divergence expected under neutral drift among populations, implying an important role for selection in driving divergence between these populations .
文摘Jack London is one of the most outstanding naturalistic writers in America who composed many renowned full-length novels.Jack London’s short story,"To Build a Fire"is a good reflection of naturalistic tendencies.It chooses"To Build a Fire"so as to fully understand his perspective of naturalism.First,it provides a brief introduction to Jack London and this short story.Second,it specifically displays naturalism in this short story from four aspects.Among them,objective authenticity is the most distinctive feature in naturalistic elements.Meanwhile,his literature creation is also deeply influenced by Darwin’s theory of evolution.It aims to investigate gold seeker’s failure that reflects natural selection and theory of survival of the fittest.Finally,it concludes that only by respecting nature can human beings survive in natural selection.Through the analysis of gold seeker’s tragic fate,it warns that the readers should master wild survival skills and live in harmony with nature.
文摘This paper presents the development process relating to the conceptual design of glass/renewable natural fibrereinforced polymer hybrid composite motorcycle side cover.Motorcycle side cover is a component frequently made from plastic or steel that functions on covering the motorcycle parts,components and systems such as frame,battery,electrical systems and mechanical systems.Function Analysis Systems Techniques(FAST)is used to identify the functions of motorcycle side cover.The right-side cover of motorcycle model SYM E-Bonus 110 has been physically studied to identify the competitive benchmarking criteria.The functions and competitive benchmarking criteria are then compiled and integrated with the environmental requirements to identify the Product Design Specifications(PDS).The coir fibre has been selected from six identified dominant renewable natural fibre used for automotive component through integration of Ranking Method and Quality Based Selection(QBS).Then the polypropylene matrix is selected after shortlisting the existing thermoplastic that is used with coir fibre and has high suitability for injection moulding manufacturing.The polypropylene matrix is then evaluated using Weighted Evaluation Matrix(WEM)by comparing to benchmark material which is Acrylonitrile Butadiene Styrene(ABS).After that,the conceptual design development of glass/renewable coir fibre-reinforced polypropylene motorcycle side cover is carried out using an integrated Theory of Inventive Problem Solving(TRIZ)and Morphological Chart,followed by final conceptual design selection using integration of Pugh Scoring Method and QBS.The conceptual design development intended on improving the biodegradability to reduce pollution to the environment.However,the usage of glass/coir fibre-reinforced polypropylene hybrid composite may increase the weight due to higher density.Four innovative design concepts have been developed and the selected final concept design has the most minimum number of ribs and minimum thickness with the same ratio of glass fibre and natural fibre composition.
文摘1 Technology of natural materials Early man used conveniently shaped stones as tools. ＂Workshop＂ areas have been found with large numbers of stones, some showing signs of being worked. However, organic materials like wood will decay under normal wet conditions in the presence of oxygen, so we won＇t find the same sort of evidence for wooden tools. It is safe to assume that early man used sticks as probes and clubs, and maybe even for making some sort of nestlike protection against the elements and predators, since we see chimpanzees and other animals doing this sort of thing. So wood, and ahnost certainly other plant materials such as fibrous leaves, and bone and other materials gleaned from dead animals, would be used from the earliest times. We need to know this in order to establish the idea that Man can be expected to have a long history of the use and manipulation of natural materials. This needs skills in choosing materials for certain uses on the basis of their mechanical properties, whether those properties are to do with the ease of shaping the material or the effectiveness of that material in use. Occasionally the material was chosen simply because it was readily available. If we find that a particular material was always used for a certain job, it＇s reasonable to deduce that Man was exerting materials selection criteria through experience.
基金support was provided by the National Natural Sciences Foundation of China(Grant 31772444 and 31471987)。
文摘Sexual dichromatism represents a major form of phenotypic differentiation between the sexes in birds,and its evolution is likely shaped by the interplay between sexual and natural selection.The genus Ficedula,widely distributed across Eurasia,exhibits pronounced interspecific variation in both sexual dichromatism and migratory behavior,making it an ideal study system for investigating the evolutionary patterns and drivers of avian sexual dichromatism.In this study,we conducted a phylogenetic comparative analysis of plumage complexity and sexual dichromatism across 32 Ficedula species.We further explored how life-history traits influence the evolution of sexual dichromatism.Our results reveal a strong positive correlation between male plumage complexity and the degree of sexual dichromatism,with males evolving plumage complexity at significantly faster rates than females.Migratory species exhibit significantly higher levels of dichromatism.Furthermore,compared to monochromatic species,sexually dichromatic species are characterized by higher latitudinal occurrence,broader geographic distributions,and greater flight capacity.These findings demonstrated how sexual and natural selection jointly drive evolution of sexual dichromatism in Ficedula within phylogenetic constraints,advancing our understanding of the evolutionary drivers of avian sexual dichromatism.
基金Supported by Science Foundation of Chuxiong Normal University(06YJRC19)Key Subject Construction of Chuxiong Normal University (05YJJSXK03 )National Natural Science Foundation of China (30760040)~~
文摘Evolution,adaptation and selection always exist in the evolutionary process of any species,which is the result of interrelation and interaction between living things and their environments,and the incarnation of natural laws in the evolutionary process of any species. Only if accurately understanding their connotation and interrelation among them,taking the evolution of living things as the line with centralizing the human sustainable development,dialectically unifying the active adaptation of the human being to their environments and oriented selection of nature and the society to species,we can acquire a better understanding of evolution of living things and a deeper understanding of the human sustainable development under biologically evolutionary background and uphold the true Darwinism,modern evolutionary point of view and the concept of current sustainable development in theory and in practice.
基金supported by the National Basic Research Program of China (2014CB138702)the National Natural Science Foundation of China (31502001)
文摘Synonymous codon usage pattern presumably reflects gene expression optimization as a result of molecular evolution. Though much attention has been paid to various model organisms ranging from prokaryotes to eukaryotes, codon usage has yet been extensively investigated for model legume Medicago truncatula. In present study, 39 531 available coding sequences （CDSs） from M. truncatula were examined for codon usage bias （CUB）. Based on analyses including neutrality plots, effective number of codons plots, and correlations between optimal codons frequency and codon adaptation index, we conclude that natural selection is a major driving force in M. truncatula CUB. We have identified 30 optimal codons encoding 18 amino acids based on relative synonymous codon usage. These optimal codons characteristically end with A or T, except for AGG and TTG encoding arginine and leucine respectively. Optimal codon usage is positively correlated with the GC content at three nucleotide positions of codons and the GC content of CDSs. The abundance of expressed sequence tag is a proxy for gene expression intensity in the legume, but has no relatedness with either CDS length or GC content. Collectively, we unravel the synonymous codon usage pattern in M. truncatula, which may serve as the valuable information on genetic engineering of the model legume and forage crop.
文摘In the past decade there has been a profusion of studies highlighting covariation between individual differences in stress physiology and behavioural profiles, here called personalities. Such individual differences in ways of coping with stress are relevant both in biomedicine, since different personalities may experience a different stress and disease vulnerability, and in behavioural ecology, since their adaptive value and evolutionary maintenance are the subject of debate. However, the precise way in which individual stress differences and personalities are linked is unclear. Here we provide an updated overview of this covariation across different species and taxa, consider its functional significance and present working hypotheses for how behavioural and physiological responses to stress might be causally linked, affecting life-history traits such as dispersal and life-span [Current Zoology 56 （6）： 728-740, 2010].
文摘The role of female sex pheromones in natural selection, particularly as a means for species recognition to avoid the generation of hybrid offspring with low fitness, has been widely explored and is generally accepted by scholars. However, the significance of sex pheromones in shaping mate choice （sexual selection） and in competition over breeding resources （social se- lection） has been largely ignored. The effect of sexual selection on sex pheromones as a sexually dimorphic signaling trait has been discounted because the amount of pheromone released by females is typically minute, while the role of sex pheromones in competition over breeding resources （other than mates） has not yet been considered. As a result of natural selection, variation in sex pheromones among females is expected to be low, and males are not expected to choose their mates among phero- mone-releasing conspecific females. Sexual selection, on the other hand, should drive the increase in pheromone variance among females, and males are expected to choose females based on this variation. Moreover, social selection resulting from more general social interactions, for example competition among females for breeding sites and food, should also promote variance among female sex pheromones. Here, we review the cttrrent evidence for each of the three selection processes acting on sex pheromones of female moths as an advertising trait. We suggest that the three selection types are not mutually exclusive but rather act together to promote different fimess components in diverse ecological situations
文摘After more than one hundred fifty years of the publication of On the Origin of Species by Darwin, scientists are still arguing on the relative importance of mutation and natural selection, on the driving force of organismal evolution, on microevo- lution and macroevolution, etc. Such periodically repeated debates appeared to have introduced more chaos than musings. What happened and why？ Have we really considered our views, opinions and arguments under the big picture of evolution before pos- ing the questions？ Or are we talking past each other？ We do need some reflections. While we believe that the current evolutionary theory is doing fine, perhaps a refinement or re-encapsulation of its knowledge framework can help promote a better understanding of the evolutionary science as a whole and blow offthe mist over the big picture [Current Zoology 61 （1）： 217-220, 2015 ].
