Evolution of cooperation without reciprocity.

A long-standing problem in biological and social sciences is to understand the conditions required for the emergence and maintenance of cooperation in evolving populations. For many situations, kin selection is an adequate explanation, although kin-recognition may still be a problem. Explanations of cooperation between non-kin include continuing interactions that provide a shadow of the future (that is, the expectation of an ongoing relationship) that can sustain reciprocity, possibly supported by mechanisms to bias interactions such as embedding the agents in a two-dimensional space or other context-preserving networks. Another explanation, indirect reciprocity, applies when benevolence to one agent increases the chance of receiving help from others. Here we use computer simulations to show that cooperation can arise when agents donate to others who are sufficiently similar to themselves in some arbitrary characteristic. Such a characteristic, or 'tag', can be a marking, display, or other observable trait. Tag-based donation can lead to the emergence of cooperation among agents who have only rudimentary ability to detect environmental signals and, unlike models of direct or indirect reciprocity, no memory of past encounters is required.     

Evolution of cooperation in a finite homogeneous graph

Recent theoretical studies of selection in finite structured populations have worked with one of two measures of selective advantage of an allele: fixation probability and inclusive fitness. Each approach has its own analytical strengths, but given certain assumptions they provide equivalent results. In most instances the structure of the population can be specified by a network of nodes connected by edges (that is, a graph), and much of the work here has focused on a continuous-time model of evolution, first described by ref. 11. Working in this context, we provide an inclusive fitness analysis to derive a surprisingly simple analytical condition for the selective advantage of a cooperative allele in any graph for which the structure satisfies a general symmetry condition ('bi-transitivity'). Our results hold for a broad class of population structures, including most of those analysed previously, as well as some for which a direct calculation of fixation probability has appeared intractable. Notably, under some forms of population regulation, the ability of a cooperative allele to invade is seen to be independent of the nature of population structure (and in particular of how game partnerships are specified) and is identical to that for an unstructured population. For other types of population regulation our results reveal that cooperation can invade if players choose partners along relatively 'high-weight' edges.     

Evolution of cooperation and conflict in experimental bacterial populations

A fundamental problem in biology is the evolutionary transition from single cells to multicellular life forms. During this transition the unit of selection shifts from individual cells to groups of cooperating cells. Although there is much theory, there are few empirical studies. Here we describe an evolutionary transition that occurs in experimental populations of Pseudomonas fluorescens propagated in a spatially heterogeneous environment. Cooperating groups are formed by over-production of an adhesive polymer, which causes the interests of individuals to align with those of the group. The costs and benefits of cooperation, plus evolutionary susceptibility to defecting genotypes, were analysed to determine conformation to theory. Cooperation was costly to individuals, but beneficial to the group. Defecting genotypes evolved in populations founded by the cooperating type and were fitter in the presence of this type than in its absence. In the short term, defectors sabotaged the viability of the group; but these findings nevertheless show that transitions to higher orders of complexity are readily achievable, provide insights into the selective conditions, and facilitate experimental analysis of the evolution of individuality.     

Evolution and maintenance of cooperation via inheritance of neighborhood relationship

Cooperative behaviors are ubiquitous in nature and human society. It is very important to understand the internal mechanism of emergence and maintenance of cooperation. As we know now, the offsprings inherit not only the phenotype but also the neighborhood relationship of their parents. Some recent research results show that the interactions among individuals facilitate survival of cooperation through network reciprocity of clustering cooperators. This paper aims at introducing an inheritance mechanism of neighborhood relationship to explore the evolution of cooperation. In detail, a mathematical model is proposed to characterize the evolutionary process with the above inheritance mechanism. Theoretical analysis and numerical simulations indicate that high-level cooperation can emerge and be maintained for a wide variety of cost-to-benefit ratios, even if mutation happens during the evolving process.     

惩罚机制对影响力不同群体合作行为演化的影响

在无标度网络中,研究惩罚机制对群体合作行为演化的影响.采用进化博弈论中重复囚徒困境博弈策略,考虑影响力的多样化,模拟分析在影响力同质和异质网络中分别引入惩罚策略对个体间合作关系的影响.仿真结果表明:在影响力同质网络中,惩罚机制会激励合作行为;在度小节点影响力大的网络中,惩罚机制也同样提高了群体合作率;而在度大节点影响力大的网络中,惩罚会使群体中策略分布趋于一个均衡状态.     

王全杰与杜邦的"板块式"合作

世界上第一张用于皮革服装的莱卡皮革,2002年7月在烟台全杰公司研制成功。全杰皮革与美国杜邦技术的“高位嫁接”,是董事长王全杰继2002年4月辞去公司总经理一职、重回科研后的再一次跨越。这一民营科技企业与世界工业巨头之间的牵手,不仅开启了世界皮革生产的新时代,也开了山东省企业与世界50强合作的先河。     

VDSL与ADSL的竞争与合作

VDSL和ADSL系列是当今解决宽带接入最后一公里的两种主要解决方案,从ADSL系列（包括第一代ADSL、ADSL2和ADSL2＋）和VDSL的频段划分和各自的技术优势等方面比较二者的优劣,最后总结二者在实际应用发挥的作用。     

大学与企业孵化器的分工与合作

大学是科学研究和技术创新的主力军，是科技成果和高科技人力资源的提供者。在信息、网络时代，大学和企业孵化器必将在经济发展中占有重要位置。大学与企业的合作带来多赢。大学从持股方式中获取长期利益，新企业又为大学毕业生提供工作就业机会，并激励大学中的其他研究人员。在合作过程中大学的分工是提供软资源，即科技成果和人才资源。企业孵化器的分工是为企业营造良好的创业环境和提供针对性的服务，形成优势互补的创新型企业。     

加强辅导员与班主任相互协作的途径

分析高校辅导员和班主任在相互协作方面存在的主要问题及原因,剖析辅导员、班主任合作的基础和优势,提出从明确责任、营造氛围、制度保障、构建交流平台、优化配置等方面来加强两者的协作。     

种子产业中外强强对接

强强联合2002年12月10日,山东登海种业集团与美国先锋海外公司(杜邦子公司)宣布,在莱州市成立合资企业山东登海先锋种业有限公司,中外双方分别拥有公司51%和49%股份。据了解,这是我国《种子法》颁布实施以来成立的第一家中外合资种业公司。双方的合资合作标志着我国最大的玉米种业公司与世界最大的玉米种业公司实现了强强联合。     

关于HPM和PME结合的研究

目的探讨HPM和PME结合的可行性。方法通过对HPM和PME的比较，以数学学习心理为依据，结合数学史对数学教学的既有研究，从数学学习层面分析数学史对数学教育的作用。结果数学史通过影响认知因素及非认知因素参与并推动数学学习活动，由此影响数学学习活动的全过程。结论与PME相结合，是HPM被数学教育界认可的一个走向。     

中俄科技合作的对策研究

科学技术是第一生产力,是一个国家综合国力的决定性因素。我国现有的科技水平在世界上并不处于领先地位,要实现科技的跳跃式发展,就必须进行技术引进。俄罗斯的科技水平在世界上是先进的,我国与俄罗斯又保持着良好的政治关系,这就为我国与俄罗斯发展科技合作铺平了道路。因此在这篇文章中要着重论述我国与俄罗斯进行科技合作的方式及对策。     

独立学院校企合作人才培养模式探索与实践

校企合作办学,培养适应企业需要的人才是当今高校教育改革的新课题.天津理工大学中环信息学院和内蒙古中环光伏材料有限公司共同开展的中环光伏教学模块目的把我校学生大学第四年的教育与企业实际生产相结合,根据学分安排和实践操作要求,由校企联合进行理论授课,给学生在企业中接受最前沿培训的机会,完成相应的考核.给青年教师平台,参与到实际生产中,近距离接触行业动态,从而探索一种合作共赢的人才培养模式.     

试论化石与生物进化关系的内在模糊性

根据现代生物进化论和古生物学成就，就化石与生物进化关系的内在模糊性予以论述。     

越南植保机械发展及中越植保机械合作分析

阐述了越南农林生产经济区域、耕作类型和植物保护现状,归纳分析越南植物保护机械的应用及存在问题,并探讨了中越植物保护机械化在植保机械开发、推广和人员培养等方面的合作研究与发展方向。     

Fine-scale recombination rate differences between sexes, populations and individuals

Meiotic recombinations contribute to genetic diversity by yielding new combinations of alleles. Recently, high-resolution recombination maps were inferred from high-density single-nucleotide polymorphism (SNP) data using linkage disequilibrium (LD) patterns that capture historical recombination events. The use of these maps has been demonstrated by the identification of recombination hotspots and associated motifs, and the discovery that the PRDM9 gene affects the proportion of recombinations occurring at hotspots. However, these maps provide no information about individual or sex differences. Moreover, locus-specific demographic factors like natural selection can bias LD-based estimates of recombination rate. Existing genetic maps based on family data avoid these shortcomings, but their resolution is limited by relatively few meioses and a low density of markers. Here we used genome-wide SNP data from 15,257 parent-offspring pairs to construct the first recombination maps based on directly observed recombinations with a resolution that is effective down to 10 kilobases (kb). Comparing male and female maps reveals that about 15% of hotspots in one sex are specific to that sex. Although male recombinations result in more shuffling of exons within genes, female recombinations generate more new combinations of nearby genes. We discover novel associations between recombination characteristics of individuals and variants in the PRDM9 gene and we identify new recombination hotspots. Comparisons of our maps with two LD-based maps inferred from data of HapMap populations of Utah residents with ancestry from northern and western Europe (CEU) and Yoruba in Ibadan, Nigeria (YRI) reveal population differences previously masked by noise and map differences at regions previously described as targets of natural selection.     

高校德文化建设与廉洁教育的协同机制研究

新形势下,开展大学生廉洁教育是丰富和完善高校传统德育内容体系的必然要求。据有关资料显示,我国的大学生廉洁教育目前正处于初步发展阶段,廉洁教育仍有较大的发展提升空间。因此,以道德文化建设为切入点,将德文化建设与大学生廉洁教育深度契合,提升大学生廉洁教育的思想内涵,并通过整合资源,构建和实现高校德育与廉洁教育的协同机制,以达到创新德育模式,深化教育效果之目的。