Social parasitism by male-producing reproductive workers in a eusocial insect

The evolution of extreme cooperation, as found in eusocial insects (those with a worker caste), is potentially undermined by selfish reproduction among group members. In some eusocial Hymenoptera (ants, bees and wasps), workers can produce male offspring from unfertilized eggs. Kin selection theory predicts levels of worker reproduction as a function of the relatedness structure of the workers' natal colony and the colony-level costs of worker reproduction. However, the theory has been only partially successful in explaining levels of worker reproduction. Here we show that workers of a eusocial bumble bee (Bombus terrestris) enter unrelated, conspecific colonies in which they then produce adult male offspring, and that such socially parasitic workers reproduce earlier and are significantly more reproductive and aggressive than resident workers that reproduce within their own colonies. Explaining levels of worker reproduction, and hence the potential of worker selfishness to undermine the evolution of cooperation, will therefore require more than simply a consideration of the kin-selected interests of resident workers. It will also require knowledge of the full set of reproductive options available to workers, including intraspecific social parasitism.     

Parasitic Cape honeybee workers, Apis mellifera capensis, evade policing.

Relocation of the Cape honeybee, Apis mellifera capensis, by bee-keepers from southern to northern South Africa in 1990 has caused widespread death of managed African honeybee, A. m. scutellata, colonies. Apis mellifera capensis worker bees are able to lay diploid, female eggs without mating by means of automictic thelytoky (meiosis followed by fusion of two meiotic products to restore egg diploidy), whereas workers of other honeybee subspecies are able to lay only haploid, male eggs. The A. m. capensis workers, which are parasitizing and killing A. m. scutellata colonies in northern South Africa, are the asexual offspring of a single, original worker in which the small amount of genetic variation observed is due to crossing over during meiosis (P. Kryger, personal communication). Here we elucidate two principal mechanisms underlying this parasitism. Parasitic A. m. capensis workers activate their ovaries in host colonies that have a queen present (queenright colonies), and they lay eggs that evade being killed by other workers (worker policing)-the normal fate of worker-laid eggs in colonies with a queen. This unique parasitism by workers is an instance in which a society is unable to control the selfish actions of its members.     

Entomology: Asian honeybees parasitize the future dead

The queen of a honeybee colony has a reproductive monopoly because her workers' ovaries are normally inactive and any eggs that they do lay are eaten by their fellow workers. But if a colony becomes queenless, the workers start to lay eggs, stop policing and rear a last batch of males before the colony finally dies out. Here we show that workers of the Asian dwarf red honeybee Apis florea from other colonies exploit this interval as an opportunity to move in and lay their own eggs while no policing is in force. Such parasitism of queenless colonies does not occur in the western honeybee A. mellifera and may be facilitated by the accessibility of A. florea nests, which are built out in the open.     

Insurance-based advantage to helpers in a tropical hover wasp

The origin and maintenance of eusociality is a central problem in evolutionary biology. Eusocial groups contain individuals that forfeit their own reproduction in order to help others reproduce. In facultatively eusocial taxa, offspring can choose whether to found new nests or become helpers in their natal groups. In many facultatively eusocial insects, offspring need continuous care during development, but adult carers have life expectancies shorter than the developmental period. When a lone foundress dies, her partly reared brood are usually doomed. Here, we show that helpers in a tropical hover wasp (Liostenogaster flavolineata) have an insurance-based advantage over lone foundresses because after a helper dies, most of the brood that she has partly reared will be brought to maturity by surviving nest-mates. After some of the helpers are experimentally removed from a multi-female nest, the reduced group is left with more brood than it would normally rear. We found that larger, more valuable extra brood were reared through to maturity, but not smaller, less valuable brood. Smaller brood may be sacrificed to feed larger brood, and reduced groups probably benefited from increased short-term helper recruitment. Rearing extra brood did not increase adult mortality or brood development time.     

Energetics reveals physiologically distinct castes in a eusocial mammal

Eusociality, which occurs among mammals only in two species of African mole-rat, is characterized by division of labour between morphologically distinct 'castes'. In Damaraland mole-rats (Cryptomys damarensis), colony labour is divided between 'infrequent worker' and 'frequent worker' castes. Frequent workers are active year-round and together perform more than 95% of the total work of the colony, whereas infrequent workers typically perform less than 5% of the total work. Anecdotal evidence suggests that infrequent workers may act as dispersers, with dispersal being limited to comparatively rare periods when the soil is softened by moisture. Here we show that infrequent workers and queens increase their daily energy expenditure after rainfall whereas frequent workers do not. Infrequent workers are also fatter than frequent workers. We suggest that infrequent workers constitute a physiologically distinct dispersing caste, the members of which, instead of contributing to the work of the colony and helping the queen to reproduce, build up their own body reserves in preparation for dispersal and reproduction when environmental conditions are suitable.     

Future fitness and helping in social queues

Helpers in primitively eusocial and cooperatively breeding animal societies forfeit their own reproduction to rear the offspring of a queen or breeding pair, but may eventually attain breeding status themselves. Kin selection provides a widely accepted theoretical framework for understanding these societies, but differences in genetic relatedness do not explain a universal societal feature: the huge variation between individuals in helping effort. An alternative explanation for this variation lies in a fundamental trade-off faced by helpers: by working harder, they increase the indirect component of their fitness, but simultaneously decrease their own future survival and fecundity. Here, we show that individuals work less hard when they stand to lose more future fitness through working. We experimentally manipulated two components of future fitness in social queues of hover wasps (Stenogastrinae): a helper's chance of inheriting an egg-laying position, and the workforce available to rear her offspring should she inherit. After each manipulation, helpers increased or decreased their effort as appropriate to the change in expected future fitness that they experienced. Although helping provides significant indirect fitness benefits for hover wasps, our study shows that variation in the costs associated with helping is the major determinant of helping effort.     

不同品级拟黑多刺蚁(Polyrhachis vicina)脑部雌激素相关受体基因的表达

采用原位杂交方法对不同品级拟黑多刺蚁(Polyrhachis vicina)脑部雌激素相关受体pvERRmRNA的表达进行了检测.结果表明,pvERRmRNA在不同品级的蕈形体、附叶、视叶、中脑、食道下神经节和球状细胞中都有表达.蚁后蕈形体和球状细胞中pvERRmRNA的阳性表达最为明显;工蚁中脑pvERR mRNA的阳性反应强度明显高于蚁后和雄蚁;pvERR mRNA在雄蚁视叶中有较强的表达.pvERR mRNA在不同品级的拟黑多刺蚁脑部的表达差异可能与它们各自在蚁群中的功能和行为有关.     

北洋政府时期铁路工会述论

北洋政府时期,铁路工会在中国出现并得以迅猛发展。铁路工会在提高工人之收入,改善工人待遇,调解路方与工人的矛盾,救济、抚恤困难工人,以及在组织工人学习、休闲、娱乐以及联络感情等方面发挥了不可或缺的作用。铁路工会组织的经济性罢工大多取得胜利,但政治性罢工却遭到失败。这说明,北洋政府时期铁路工会作用的发挥,一方面取决于其自身组织状况,另一方面也取决于当时的政治环境。     

黑盾胡蜂的生物学习性

对黑盾胡蜂( Vesp a bicolor ) 的生物学习性进行了研究. 结果表明: 出蛰雌蜂5 月中旬觅址筑巢, 单母建群, 历时36 d 建成具34 个巢房的小巢, 此时雌蜂兼备职蜂和后蜂职能; 该蜂卵期3. 5~ 5. 5 d, 幼虫期10~ 12 d, 蛹期10. 5~ 12. 5 d, 完成发育需24~ 30 d, 并与气温密切相关; 雌蜂日外勤晴天多达42 次, 每次捕食外勤费时6~ 22 min; 职蜂出房后第3 天开始外勤, 雌蜂随即停止外勤专司产卵, 1 a 仅一世代, 12 月中旬弃巢结团越冬. 黑盾胡蜂亲代个体群居分工合作有利于生存和种族繁衍.     

大学生的内隐攻击实验研究及其与外显攻击的关系

个体攻击的发生发展机制一直是攻击的心理学研究中重要的基础问题,但以往研究较多关注个体的外显攻击．对内隐攻击的研究相对较为匮乏．本研究拟在中国文化背景下考察大学生的内隐攻击与外显攻击的发生特点,包括攻击的性别差异及类型差异,并在此基础上探讨内隐攻击与外显攻击的关系．以190名大学生为被试,采用任务分离范式中的偏好测验测评被试的内隐攻击,采用自我报告的攻击问卷测评被试的外显攻击．1）在外显攻击上,男性身体攻击显著高于女性,言语攻击和关系攻击的性别差异不显著;个体言语攻击显著高于身体攻击、关系攻击,身体攻击和关系攻击之间差异不显著．2）在内隐攻击任务上,相对于攻击词,被试更加偏好中性词．3）内隐攻击的性别差异与类型差异均不显著．4）大学生的内隐攻击与外显攻击之间不存在显著关联．结论：内隐攻击与外显攻击存在性别差异与类型差异,两类攻击间无显著相关,支持内隐一外显结构分离论．     

城市化进程的瓶颈——农民工社会保障的缺失

农民工是一个在城市化进程中只完成了职业转换却没有完成身份转换的特殊社会群体。农民工的形成和发展,既促进了我国工业化和现代化进程,又成为城市化的突出矛盾。要保证城市化的健康发展,必须妥善解决好“农民工问题”,其中完善农民工的社会保障又是解决农民工问题最重要的一环,其实质是逐步推动农民工彻底地完成城市化过程。     

Aggression by polyembryonic wasp soldiers correlates with kinship but not resource competition

Kin selection theory predicts that individuals will show less aggression and more altruism towards relatives. However, recent theoretical developments suggest that with limited dispersal, competition between relatives can override the effects of relatedness. The predicted and opposing influences of relatedness and competition are difficult to approach experimentally because conditions that increase average relatedness among individuals also tend to increase competition. Polyembryonic wasps in the family Encyrtidae are parasites whose eggs undergo clonal division to produce large broods. These insects have also evolved a caste system: some embryos in a clone develop into reproductive larvae that mature into adults, whereas others develop into sterile soldier larvae that defend siblings from competitors. In a brood from a single egg, reproductive altruism by soldiers reflects clone-level allocation to defence at the cost of reproduction, with no conflict between individuals. When multiple eggs are laid into a host, inter-clone conflicts of interest arise. Here we report that soldier aggression in Copidosoma floridanum is inversely related to the genetic relatedness of competitors but shows no correlation with the level of resource competition.     

网络入侵检测规则的冲突检测和解决

为了解决入侵检测系统中当前输入事件同时匹配入侵规则库中多条规则(检测冲突)从而导致漏报和误报的问题,利用形式化方法研究了冲突的类型和判定标准,给出了冲突检测和解决的算法.对Snort规则库分析的结果表明:提出的冲突判定标准正确有效,且冲突在规则库中实际存在并以交叉冲突为主.因此依靠专家经验建立的规则库不可避免地存在语义矛盾,对规则库进行冲突检测和冲突解决有助于提高入侵检测系统的有效性.     

传统文化视域下大学生核心价值观的构建

当代大学生价值观的主流是积极进取、健康向上的,但也呈现出一定的矛盾性与冲突性。优秀传统文化是克服当代大学生价值观矛盾冲突的重要资源。高校思想政治工作者要积极探索用传统优秀文化构建大学生核心价值观的有效策略与途径。     

论遗体捐献自我决定权与近亲属决定权的冲突与协调

自然人基于身体权享有捐献其遗体的自我决定权,其近亲属基于对尸体的所有权也享有对遗体的捐献权利.由于权利的排他性等因素,二者可能会发生冲突,从而阻碍遗体捐献的发展.目前,国际上解决这一问题存在“自我决定权优先模式”以及“等同模式”.自我决定权优先模式无法很好解决这一问题.等同模式解决两权利的冲突符合我国传统伦理,便于遗体捐献的执行顺利进行,也可以提高遗体捐献的概率,故我们国家未来遗体捐献立法对于遗体捐献自我决定权近亲属决定权的冲突应当采取“等同模式”.     

非公有制企业女工劳动权益保护存在的问题及对策

在非公有制企业中，侵害女工劳动权益的现象比较普遍。除了劳动力供大于求和一些地方政府认识不到位外，还有法律不健全、执法不严、企业经营者违法以及女工自身素质较低等方面的原因。完善法律法规、加大普法宣传力度、严格执法、发挥工会维权功能、规范劳动力市场和提高妇女就业能力是保护女工劳动权益的有效途径。     

河南省城市农民工参与体育活动现状调查与分析

通过文献资料法和调查法,对河南省城市农民工参与体育活动的状况进行了调查与分析.结果发现:农民工以青壮年为主,多为初中文化程度,只有少部分人与老乡、工友一起参与体育活动;活动内容以散步、跑步以及街头、小区的健身器械为主;活动场地以公园、街道和广场为主.影响农民工参与体育活动的因素主要是:工作强度大,缺少时间和精力,缺少体育运动技能和运动场地器材等.     

论伊丽莎白一世的外交政策

伊丽莎白一世是英国历史上著名的君主，她统治英国长达四十馀年。这期间既是英国社会经济、政治、文化、宗教、外交诸方面发生剧烈变化的时期．也是英国向近代化道路迈进的时期。她的外交政策不仅对英国社会而且对欧洲政治发展产生重大作用。十六世纪六十年代末以前，她利用西法矛盾．建立英西联盟关系，把西班牙作为英国主要的国际支柱，对抗法国，提高英国在国际政治中的地位。此后，随着英国资本主义工商业迅速发展，迫切需要扩大海外贸易，寻找新的市场，长期拥有海上霸权的西班牙又成为英国对外扩张的主要障碍，为此，伊丽莎白女王改变外交政策，转而同法国结盟对抗西班牙．开辟了英国外交的新时代。     

Royalactin induces queen differentiation in honeybees

The honeybee (Apis mellifera) forms two female castes: the queen and the worker. This dimorphism depends not on genetic differences, but on ingestion of royal jelly, although the mechanism through which royal jelly regulates caste differentiation has long remained unknown. Here I show that a 57-kDa protein in royal jelly, previously designated as royalactin, induces the differentiation of honeybee larvae into queens. Royalactin increased body size and ovary development and shortened developmental time in honeybees. Surprisingly, it also showed similar effects in the fruitfly (Drosophila melanogaster). Mechanistic studies revealed that royalactin activated p70 S6 kinase, which was responsible for the increase of body size, increased the activity of mitogen-activated protein kinase, which was involved in the decreased developmental time, and increased the titre of juvenile hormone, an essential hormone for ovary development. Knockdown of epidermal growth factor receptor (Egfr) expression in the fat body of honeybees and fruitflies resulted in a defect of all phenotypes induced by royalactin, showing that Egfr mediates these actions. These findings indicate that a specific factor in royal jelly, royalactin, drives queen development through an Egfr-mediated signalling pathway.     

证据特征提取及其在证据理论改进中的应用

尽管DS证据理论可以有效地处理不确定性信息,但是在证据高度冲突情况下,经典DS证据组合规则因归一化过程往往会产生有悖常理的融合结果.为此,很多学者提出了许多不同的修改方法,可以归为两类修改组合规则和修改证据.在总结这两类修改思路的基础上,分析了几种代表性的改进方法,同时通过引入证据距离,对证据源进行特征提取,提出了相应的改进方案.理论分析和数值实验结果表明,改进后的3种方法不仅能充分体现相应的改进思想,而且可以更好地实现证据组合,较快地收敛真实目标,得到合理的融合结果.